最新刊期
卷 57 ， 期 2 ， 2018
- 摘要：Maxianshan nephrite ore in Gansu Province was found in the Neoproterozoic Maxianshan group, a set of metamorphic strata consisting of migmatite, marble and biotite schist, which was regarded as one of the most important material sources of the nephrite jadewares of the Qijia Culture. In order to find out the probability of the Maxianshan nephrites as the raw materials of the nephrite jadewares of the Qijia Culture, the combined field investigation and instrumental analyses of XRD, SEM, EMPA, ICP-MS and LA-ICP-MS are applied to analyze the mineralogy, petrology and geochemisty of Maxianshan nephrites and their country rocks, including mineral composition, structure feature, and chemical composition of the nephrites such as major & trace elements, rare earth elements, and therefore to explore the mineralization of the Maxianshan nephrite mine. The main findings are summarized as follows: ① Maxianshan nephrites are yellow-white to yellow-green (mostly green) in color, characterized by lamellar amorphous structure and fiber interwoven structure, and composed of more than 98% amount of tremolite mineral and tiny amount of sphene, zoisite and apatite minerals; ② The tremolite minerals in nephrites were formed in three mineralization periods, and the principal nephrite ore is mainly related to the tremolites of middle and late periods. The formation of jade grade nephrites was associated with marbleization caused by metasomatism in connection with late intruded alkali granites; ③ The Maxianshan nephrite is characterized by high Th/U, low Cu and REE element, and seagull REE distribution pattern, being different from other nephrites from Hetian of Xinjiang, Qinghai and Liaoning.关键词：nephrite;mineralization;geochemistry;origin characteristics;Maxianshan of Gansu
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发布时间：2023-12-11 - 摘要：Based on the ASTER DEM data, this paper adopted hypsometric theory to study the quantitative representation of the evolution stages of Danxia landform. The result indicates that the hypsometric curve is changed from convex to concave with the development of Danxia landform from young to mature, and the concave features are gradually strengthened, while the HI value is getting smaller and smaller, which is consistent with the law of Danxia landform evolution. Based on the comparative study of different sub-zones in the same Danxia landform region, hypsometric curve and index can reflect the multi-stage evolution in the same Danxia landform region. In addition, the comparative study of the same area shows that there is a general scale effect in the evolution phase of Danxia landform, which needs to be fully considered in the calculation of hypsometric curve and index.关键词：Danxia landform;DEM;hypsometry;evolution stage;quantitative research
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发布时间：2023-12-11 - 摘要：The Pearl River Estuary, located at the downstream of the Pearl River Delta, receives freshwater from multisources and is an active transition zone between river environments and maritime environments. The variation of water optical properties with tide remains to be further studied. Based on the fixed point measurement during 4 days in the Pearl River Estuary, The averaged CDOM (chromophoric dissolved organic matter) concentration ag(355) is 1.01±0.31 m-1at flood tide while the value is 1.18±0.37 m-1at ebb tide. It shows the temporal feature that the values at ebb tide are higher than those at flood tide. From the spatial dimension, ag(355) inside the estuary entrance is higher than that outside. It fluctuates weakly both inside the estuary entrance at ebb tide and outside the entrance at flood tide. The averaged Sg(spectral slope of CDOM absorption coefficient) is 0.018 6±0.002 9 nm-1at flood tide and it shows a lower value (0.017 7±0.002 3 nm-1) at ebb tide. The values at ebb tide are closer to each other in space. Sghas significantly positive correlation with the molecular size M (absorbance ratio between 250 and 365 nm), both of them show high values at flood tide. In addition, there is remarkable negative correlation between ag(355) and salinity for the outer estuary. And the correlation at ebb tide is superior to that at flood tide. However they have no common bond inside the entrance during flood season. Therefore, the optical properties of CDOM at ebb tide appear to be more stable, particularly for those of the inner estuary. And the tidal effects should be considered in retrieving water quality parameters from remote sensing data.关键词：CDOM;absorption;tide;Pearl River Estuary
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发布时间：2023-12-11 - 摘要：This study used GIS technique and RUSLE model to analyze the dynamic impacts on soil erosion in the Dongjiang river basin, a gradient development basin, based on the landcover data in years 1990, 2000 and 2010 The results showed that the landcover in the downstream areas presented a large variation with a large number of paddy field, nonirrigated farmland, forestland and grassland converting to urban land, construction land and garden plot. The average soil erosion amounts reach 15.22 t/ (hm2·a), 15.41 t/ (hm2·a) and 15.47 t/ (hm2·a), all of which belong to Level II but increased over the time. The percentage of the erosion areas belonging to Levels I-II ranges 90.95% to 91.26%. The level change of soil erosion is not significant: approximately 24328km2(91.14%) areas maintained the original levels, but approximately 2365 km2(8.86%) changed; among the changed areas, approximately 1286 km2(4.82%) was converted from lower levels to higher levels, but approximately 1079 km2(4.04%) was converted from higher levels to lower levels. The spatial distribution and its dynamic variation matched well with the gradation development of social economy, which showed an increasing trend from the upstream to downstream.关键词：erosion;soil conservation;precipitation;RUSLE;GIS;Dongjiang River basin
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发布时间：2023-12-11 - 摘要：The historic district is the memory of a city, which makes a great influence on city development. Having a good understanding of the historic district is conductive to the protection, inheritance and development of a city in culture. In this paper, temporal-spatial evolution research method in geography was applied to study the evolution of Xiaogongyuan district, the origin of Shantou city, focusing on figuring out its development stages and influence factors. The results are as follows: ① the development of Xiaogongyuan district can be clearly divided into three periods of the rising, prosperity and decline periods. ② The characteristic of periods was the result of the interaction of geographical, economic, administrative and social factors, which once played an unequal role in intensity and efficiency in each period owing to spatial expansion and functional change of Shantou city. ③ As the original place of Shantou, Xiaogongyuan district has been considered as an iconic place associating with Shantou identity. In the future, more attention should be paid on promoting its protection and reconstruction, rebuilding its characteristic and function, and hence renewing its vitality in the development of Shantou city.关键词：historic district;Xiaogongyuan district of Shantou;evolution
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发布时间：2023-12-11 - 摘要：Structural magnetic resonance imaging (SMRI) method has an intrinsic thirdorder tensor structure. Traditional vectorbased machine learning methods unfold the 3D images as vectors to carry on the modeling, which break the natural 3D structure of data so that some useful information underlying the neuroimaging data is missing. Therefore, a novel classification method based on the Support Tensor Machine (STM) is proposed to overcome these drawbacks. The T1 weighted MRI images are first preprocessed and segmented into gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF) regions using SPM8 tool. The third-order grey tensors are then constructed for each partition. Recursive feature elimination (RFE) method coupled with Support Tensor Machine (STM) is used to select the optimal features subset for classification using the STM-based classifier. The proposed algorithm perform the classification on four cases including the patients of Alzheimers disease and Mild Cognitive Impairment (including patients were converted to AD, MCI-C; and patients were not converted to AD, MCI-NC) and normal controls (NC), 10-fold cross validation is employed to assess the classification performance. In terms of AUC, classification accuracy, sensitivity and specificity, the case AD vs NC archive 99.1%, 97.14%, 95.71%, 98.57% respectively; the case AD vs MCI archive 8829%, 84.07%, 78.57%, 91.07% respectively; the case of MCI vs NC archive 89.18%, 87.91%, 93.75%, 78.57% respectively; and the case MCI-C vs MCI-NC archive 87.5%, 82.08%, 80.36%, 82.14% respectively The proposed method keeps the natural tensor structure of the original data and improves the performance of the classifier. The experimental results indicate that the proposed algorithm is effective for the diagnosis of Alzheimers disease.关键词：Alzheimer's disease;3D brain white matter image;T1 weighted MRI;Recursive feature elimination;Support Tensor Machine
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发布时间：2023-12-11 - 摘要：The research of zerosum problems over finite abelian groups has a long history, while there are only a few results concerned about zero-sum problems over infinite groups. The minimal zero-sum sequences over integers are studied. The structure of minimal zero-sum sequences over an integral interval ［－m,n］ whose lengths are at least n+m－2 is obtained.关键词：sequences;zero-sum;minimal zero-sum;Davenport constant
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发布时间：2023-12-11 - 摘要：The existence of solutions to a p-Laplace equation is studied. The source term f only lies in L1which is the main feature of the problem. With the help of the regularizing effect between the coefficient of the lower order term and the source term, a priori L∞regularity for its weak solutions is proved. B-y the uniform L∞bound, the existence of weak solutions is obtained.关键词：p-Laplace equations;L1datum;bounded weak solutions
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发布时间：2023-12-11 - 摘要：The problem of the characteristic inequality in 2-uniformly convex spaces is discussed by using the method of Banach space theory. The characteristic inequality of the 2-uniformly rotund Banach spaces is given as a generalization of the characteristic inequality in the uniformly rotund Banach spaces which was given by Zong-Ben Xu and Roach.关键词：2-uniformly rotund Banach space;2modulus of rotundity;characteristic inequality
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发布时间：2023-12-11 - 摘要：The Lie symmetry and conserved quantity for nonholonomic systems of non-Chetaev's type on time scales are studied. Firstly, the differential equations of motion for nonholonomic systems of non-Chetaev's type on time scales are given. Secondly, based on the invariance of differential equation under the infinitesimal transformations, the determinating equation is established and the restriction equations for nonholonomic systems of non-Chetaev's type are given. Then, the Lie theorem and conserved quantity for nonholonomic systems of non-Chetaev's type on time scales are built. Finally, an example is given to illustrate the application of the results.关键词：time scales;non-Chetaev's type;nonholonomic systems;Lie symmetry;conserved quantity
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发布时间：2023-12-11 - 摘要：Restricted permutation is considered as important study in combinatorial enumeration. A class of enumerating problems for restricted permutation is studied by using principle of inclusion-exclusion and other combinatorial analysis methods. Some enumerating methods and enumerating formulas for restricted permutation are obtained. These results generalize some known results. Finally, enumerating problem of restricted permutation for future study is given.关键词：principle of inclusion-exclusion;restricted permutation;circular permutation;enumerating formula
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发布时间：2023-12-11 - 摘要：According to the inplane nonlinear elastic instability of circular arch with initial geometrical defects， the displacement loading device is designed to measure real-time loading-displacement curves in the loading process. And the actual deformations and unstable modes of circular arch are tracked, further, the buckling equilibrium path of circular is obtained, by which the up and lower instability limit points are captured. By comparing the measurement results with the FEA results, it can be revealed that how the span ratio and the defects of arch influence the instability limit points and unstable mode. It is showed that: 1) The initial geometric defects will influence the load-displacement curves of the arch, which makes the upper and lower limit stability points deviate from the ideal curves;2) Due to the initial geometric defect, the anti-symmetric deformation trend occurs in the unstable equilibrium path;3) With the increase of the ratio span, the instability limit load will improve, then the bearing capacity of the structure will enhance according;4) The effect of initial geometric defects on the pre buckling mode is more obvious than the post buckling mode.关键词：circular arches;initial geometrical defects;in-plane instability;non-linear;concentrated load
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发布时间：2023-12-11 - 摘要：In order to solve the problem of the decrease of flexural capacity of reinforced concrete (RC) beams, this paper proposes a new approach of steel plateCFRP composite reinforcement: the steel plates are anchored at the bottom of the reinforced concrete beam, and carbon fiber reinforced polymer (CFRP) sheets are pasted on the steel plates after having been prestressed. The calculation formula for normal section flexural capacity of the composite reinforcement beam in balancedreinforced failure is derived, and the results got by the calculation formula are compared with the test results in relevant literature. The results show that theoretical value is close to test value of relevant literature, the failure modes of beams in the test are consistent with predicted failure modes. Compared with the prestressed CFRP sheet reinforcement, the values of ultimate moment of RC beams strengthened with prestressed CFRP sheets and steel plates increase 37.4%~57.1%, the values of yield moment increase 60.4%~95.7%; Compared with the steel plate reinforcement, the values of ultimate moment increase 25.4%~39.7%. It shows that steel plate-CFRP combination reinforcement technology improves flexural behavior of RC beams effectively.关键词：bridge engineering;prestressed CFRP sheets;steel plates;composite reinforcement;resisting flexural strength
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发布时间：2023-12-11 - 摘要：HCFC-141b selected as a object, a fluoro dichloroethane hydrate was prepared by static method ; The preparation time of hydrate slurry in various concentration and the change of solution were recorded to predict the preparation conditions of gas hydrate slurry. The gas hydrate slurry with good fluidity is prepared by mixing tank type reactor according to the reagent ratio of the gas hydrate slurry. The flow parameters of hydrate slurry in different concentrations was determined. And the main phase-water velocity profile, hydrate particle concentration distribution and the GHS concentration distribution on different cross section was obtained using the Fluent simulate software, to show the flow condition of GHS in the annular pipe.关键词：nature gas;hydrate slurry;preparation;flow characteristic
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发布时间：2023-12-11 - 摘要：The design of the refrigeration system is an important part of the optimization management of the computer center, which also has a direct impact on the stable operation of the internal equipment. In this paper indoor temperature was measured with the traditional measurement method, and the fluid field and temperature field were simulated by computational dynamics fluid (CFD) method. The numerical results are in agreement with the experimental results to within the relative error of 0.22%, which ensures the reliability and lays a foundation for the further analysis of the air distribution. The results indicate that the vortex has important influence on the temperature distribution; and cooling rate in the vortex region is lower about 25% compared with the adjacent.关键词：cooling;optimization;air distribution;vortex
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发布时间：2023-12-11 - 摘要：In order to improve the process of micron wood fiber cutting, an improved particle swarm algorithm and BP neural network based on the combination of optimization algorithm is proposed to achieve the precision machining of micron wood fiber. The error back propagation algorithm is used to achieve the best structure selection of the complex relationship between cutting parameters. The improved particle swarm optimization algorithm (PSO) solves the defect of local minimum convergence of BP network, and gives a scientific and reasonable output of cutting parameters. The precision and effectiveness of the precision training of the algorithm are verified by the simulation and optimization experiments of the cutting parameters of different tree species. The research shows that the improved optimization algorithm proposed in this paper can predict the cutting parameters of the wood to be processed and has a high training precision.关键词：wood fiber cutting;cutting parameter optimization;BP neural network;particle swarm optimization algorithm
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发布时间：2023-12-11 - 摘要：This study investigated the optical isomers of lysine molecules with single hydrogen bonds between amino and carboxyl groups, catalysis of water molecule clusters, hydroxyl radical induced lysine damage mechanism and water solvent effect using the B3LYP method of density functional theory, the MP2 method of perturbation theory, and smd model method of self consistent reaction field theory. Study on the reaction channels showed that: the title reaction has two channels A and B, which are stepwise mechanism and synergistic mechenism, respectively. The potential energy surface calculation showed that channel a is the main reaction channel for the isomerization of carboxyl and proton transfer, and the Gibbs free energy barrier is 259.90 kJ·mol-1. The catalysis of two water molecule clusters reduces the barrier of channel a to 145.80 kJ·mol-1and the water solvent effect further reduces the barrier to 111.22 kJ·mol-1Hydroxyl radical and water molecule chain as hydrogen transport medium can cause lysine damage. The energy barrier in water vapor phase is 134.12 kJ·mol-1and the water solvent effect makes this barrier fall to 32.62 kJ·mol-1.关键词：optical isomers;lysine;density functional theory;transition state;perturbation theory;Gibbs free energy;hydroxyl radical;damage
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发布时间：2023-12-11 - 摘要：Kouyanqing Granule (KYQG) is a famous Chinese herbal formula for the treatment of oral diseases in clinic. Based on the Disease-syndrome theory of traditional Chinese medicine, the present study established an oral ulcer rat model with Yin-xu-huo-wang syndrome by the combination of 3,3′,5triiodothyronine injection and phenol burning. Through this rat model, KYQG's protective effects on reducing oral damage and promoting ulcer healing were evaluated including parameter detection and histopathological observation.关键词：Kouyanqing Granule;Yin-xu-huo-wang syndrome;oral ulcer;rat model;protective effects
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发布时间：2023-12-11 - 摘要：Conotoxin lt1c was identified from the cDNA library of venom gland of Conus litteratus .To obtain enough lt1c and investigate the bioactivities, conotoxin lt1c was recombinant and expressed in Escherichia coli by fusion with TRX. Conotoxin lt1c was purified by affinity chromatography, enzyme digestion and gel filtration chromatography. The recombinant lt1c showed obvious inhibition activity on the neuromuscular transmission on the frog sciatic/cutaneus pectoris preparation at the concentration of 6 μmol/L in 30 min. lt1c appeared potent and longer-lasting analgesics in the hotplate pain model mice. Additionally, lt1c showed toxicity to mice by intraventricular injection. The successful expression of lt1c with potential analgesicactivity provided the possibility for further pharmaceutical research.关键词：A-superfamily;conotoxin;recombinant expression;analgesic
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发布时间：2023-12-11 - 摘要：Crocin pretreatment markedly improved the neurological dysfunction and decreased the infarct volume in a dosedependent manner in middle cerebral artery occlusion (MCAO) rats. Western blot analysis showed that crocin up-regulated B-cell lymphoma 2 (Bcl-2) expression， down-regulated Bcl-2 associated protein X (Bax) and cleaved caspase-3 expression of hippocampus in MCAO rats. Because oxidative/nitrative stress is a very important factor in ischemiareperfusion (I/R) injury, thus, a sodium nitroprusside (SNP)-impaired PC12 cell model was set up to mimick nitric oxide (NO) excitotocixity in I/R brain. The results showed that crocin protected PC12 cells against SNP-induced cytotoxicity via attenuating the caspase activation and mitochondrial dysfunction in vitro . Crocin significantly attenuated apoptosis, lactate dehydrogenase (LDH) release, caspase-3 activation, mitochondria membrane potential corruption and the intracellular accumulation of ROS induced by SNP in PC12 cells. Moreover, SNP decreased the expression level of Bcl-2, induced the expression of cytochrome c and Bax in PC12 cells, which is similar to the case of hippocampus in MCAO rats; and crocin reversed all these effects. All these evidences support that crocin is an effective agent to protect I/R injury via reasonable mechanism.关键词：crocin;cerebral ischemia;ischemic-reperfusion (I/R);oxidative/nitrative stess;apoptosis;sodium nitroprusside
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发布时间：2023-12-11 - 摘要：The long wave ultraviolet (UVA)was used to radiate mouse fibroblast cell line (NIH 3T3) and establish a model of cell injury in order to probe the protective function and mechanism of Aloe vera gel in cell oxidative damage. After UVA radiated NIH 3T3 cells, the effects of different concentrations of Aloe vera gel on the proliferation and antioxidant enzyme activities of NIH 3T3 cells were detected by CCK-8 and biochemical colorimetric assay respectively. The results show that UVA radiation caused a significant damage to the NIH 3T3 cell, but 100, 200, 400 μg·mL-1. Aloe vera gel can improve the proliferation activity of damaged cells, increase the content of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in cells. It can simultaneously decrease the activity of lipid peroxidase. In conclusion, that UVA could damage NIH 3T3 cells, while 100~400μg·mL-1. Aloe vera gel can antagonize the damage of NIH 3T3 cells induced by UVA and have the effect of light protection.关键词：Aloe vera gel;NIH 3T3;UVA
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发布时间：2023-12-11 - 摘要：Ecological floating-beds vegetated with Vetiveria zizanioides , Iris pseudacorus and Apium graveolens , as well as their combinations were constructed to evaluate their allelopathic effects on 6 phytoplankton species. The results showed that V. zizanioides floatingbed significantly inhibited the growth and Chl a content of tested algae, while I. pseudacorus floating bed stimulated the growth and Chl. a content of some phytoplankton species. Foatingbed vegetated with V. zizanioides + I. pseudacorus + A. graveolens also inhibited the growth and Chl. a content of the tested algae, and the inhibitory rate was similar to V. zizanioides floatingbed , but higher than that of V. zizanioides + I. pseudacorus and V. zizanioides + A. graveolens . Study of MDA content in the tested algae showed that floating-beds of V. zizanioides and V. zizanioides + I. pseudacorus + A. graveolens caused a significant oxidative stress to the algae, inducing an increase in the lipid peroxidation in the algal cells. On the contrary, floating-beds vegetated with I. pseudacorus , A. graveolens or I. pseudacorus + A. graveolens had no effects on MDA content of the algae. Our study indicated that V. zizanioides has significant allelopathic effects on phytoplankton, while the allelopathic effects of A. graveolens and I. pseudacorus are much weaker. Our results also suggested that planting the three species together might caused interspecific synergism, which increased the inhibitory efficiency of the floatingbeds to the phytoplankton. The results are of importance value in the design and plant selection of ecological floating bed.
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发布时间：2023-12-11
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