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Search Results: 1 - 10 of 104213 matches for " Zhang Zhennan "
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Xiaokai Wu,Xiaoqing Cai,Xianan Zheng,Zhennan Zhang
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810043606
Abstract: The title compound, C19H20O5, is approximately planar; the dihedral angle between the benzene rings is 3.82 (8)°, and the central propenone C(=O)—C=C plane makes dihedral angles of 1.95 (10) and 3.17 (11)° with the two benzene rings. In the crystal structure, intra- and intermolecular C—H...O hydrogen bonds are observed.
On Analysis of Tangshan Pre-Hospital Service Efficiency Based on Improved Fuzzy-DEA  [PDF]
Qiaozhi Sang, Fengzhu Yao, Shuo Hao, Zhennan Zhang
Open Access Library Journal (OALib Journal) , 2018, DOI: 10.4236/oalib.1104720
An allocation model based on improved Fuzzy-DEA is proposed for Tangshan medical health resource. The membership function is particularly introduced to characterize the non-strict partial order relation of the fuzzy numbers, and the internal form of the unit efficiency values is converted into point values. The variance analysis index system is then used to find factors leading to non-DEA effectiveness and the allocation plan is recommended accordingly: the relevant departments should coordinate the inter-regional resources and optimize the medical staffing level.

ZHANG Zhennan,GE Xiurun,

岩石力学与工程学报 , 2007,
Abstract: Virtual multi-dimensional internal bonds(VMIB) is a multiscale mechanical model developed from virtual internal bond(VIB).It is deemed that the material particles in microscopic are connected with virtual normal bond and shear bond or with normal bond possessing normal and shear stiffness.The macro-constitutive relation in terms of bond stiffness is derived from the interaction between material particles.Owing to its ability to present the diversity of Poisson ratio,VMIB can be applied to more extensive engineering materials.The heterogeneous material,e.g.rock,is composed of different components.The mechanical property varies with location.In order to model the heterogeneous material,thereafter,to simulate its fracture process,the heterogeneity is primarily incorporated into VMIB.The heterogeneous material is assumed to consist of unit cells in which the virtual bonds are spatially randomly distributed.To represent the heterogeneity,the mechanical property of unit cells is assumed to be randomly distributed,which leads to a heterogeneity property on the integrated material level.However,the bond stiffness in a certain unit cell is assumed to be uniform,which leads to a homogeneity property on the cell level.To examine the performance of the presented method,the fracture process of a specimen subjected to confining stress is simulated.In the case where the rock is treated as a homogeneous solid,a run-through shear fracture is observed and the trace of fracture is regular while in the case that the rock is treated as a heterogeneous solid.Many fractures are observed to simultaneously initiate randomly in different locations;and then propagate and finally coalesce.But the general trend is of shear failure.The simulation results show that the presented method could simulate the fracture processes of heterogeneous rocks and primarily reflect the effect of heterogeneity on the failure behaviors of heterogeneous rocks.

Zhang Zhennan,Mao Xianbiao,GuoGuangli,

岩石力学与工程学报 , 2003,
Abstract: Through the experimental research on the compaction of friable rock block, the relationship among deformation modulus, axial stress and strain were obtained. The result of this experiment reveals that the tangential modulus is exponential with axial stress, and varies with rock block size and rock property. The secant modulus is linear with axial stress. Both the tangential modulus and secant modulus are exponential with axial strain. The conclusion of this research is valuable to analysis of deformation mechanism of friable rock compaction.
Expression and Purification of Integral Membrane Fatty Acid Desaturases
Haiqin Chen, Zhennan Gu, Hao Zhang, Mingxuan Wang, Wei Chen, W. Todd Lowther, Yong Q. Chen
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0058139
Abstract: Fatty acid desaturase enzymes perform dehydrogenation reactions leading to the insertion of double bonds in fatty acids, and are divided into soluble and integral membrane classes. Crystal structures of soluble desaturases are available; however, membrane desaturases have defied decades of efforts due largely to the difficulty of generating recombinant desaturase proteins for crystallographic analysis. Mortierella alpina is an oleaginous fungus which possesses eight membrane desaturases involved in the synthesis of saturated, monounsaturated and polyunsaturated fatty acids. Here, we describe the successful expression, purification and enzymatic assay of three M. alpina desaturases (FADS15, FADS12, and FADS9-I). Estimated yields of desaturases with purity >95% are approximately 3.5% (Ca. 4.6 mg/L of culture) for FADS15, 2.3% (Ca. 2.5 mg/L of culture) for FADS12 and 10.7% (Ca. 37.5 mg/L of culture) for FADS9-I. Successful expression of high amounts of recombinant proteins represents a critical step towards the structural elucidation of membrane fatty acid desaturases.
Bloch dynamics with second order Berry phase correction
Jianfeng Lu,Zhennan Zhou
Mathematics , 2015,
Abstract: We derive the semiclassical Bloch dynamics with the second order Berry phase correction, based on a two-scale WKB asymptotic analysis. For uniform external electric field, the bi-characteristics system after a positional shift introduced by Berry connections agrees with the recent result in the physics literature.
On the classical limit of a time-dependent self-consistent field system: analysis and computation
Shi Jin,Christof Sparber,Zhennan Zhou
Physics , 2014,
Abstract: We consider a coupled system of Schr\"odinger equations, arising in quantum mechanics via the so-called time-dependent self-consistent field method. Using Wigner transformation techniques we study the corresponding classical limit dynamics in two cases. In the first case, the classical limit is only taken in one of the two equations, leading to a mixed quantum-classical model which is closely connected to the well-known Ehrenfest method in molecular dynamics. In the second case, the classical limit of the full system is rigorously established, resulting in a system of coupled Vlasov-type equations. In the second part of our work, we provide a numerical study of the coupled semi-classically scaled Schr\"odinger equations and of the mixed quantum-classical model obtained via Ehrenfest's method. A second order (in time) method is introduced for each case. We show that the proposed methods allow time steps independent of the semi-classical parameter(s) while still capturing the correct behavior of physical observables. It also becomes clear that the order of accuracy of our methods can be improved in a straightforward way.

Xue Zengquan Liu Weimin Hou Shimin Shi Zujin Gu Zhennan Liu Hongwen Zhang Zhaoxiang,

电子与信息学报 , 1999,
Abstract: The single-walled carbon nanotubes(SWCNTs) are synthesized and purified. A water colloid of SWCNTs is prepared and used to assemble SWCNTs on a gold film surface. Its STM image shows sorter SWCNTs standing-on gold film surface. The crystal grain image of gold thin film and an atomic structure of highly oriented pyrolytic graphite (HOPG) are observed using a scanning tunneling microscope (STM) with the SWCNT tip made from the water colloid mentioned above. The SWCNTs standing-on gold film surface is very important for measuring electronic properties of carbon nanotubes, fabricating field emission cathode, structuring nanoelectronic devices, and making tips of a scanning probe microscope (SPM).
Expression and Significance of Clusterin in Anip973/CDDP Cell Lines
Xuesong CHEN,Zhennan TIAN,Dandan LI,Jiaqi CHEN
Chinese Journal of Lung Cancer , 2009,
Abstract: Background and objective Clusterin (CLU) is a multifunctional protein which attracts much attentions in recent years due to its function and variation in tumor formation and development. So far, there have no reports on its variation in lung cancer and its relationship with sensitivity of anti-cancer drugs. This study was to compare the expression of clusterin in wild Anip973 and Anip973/CDDP, thus to investigate the correlation of clusterin expression to tumorigenesis, tumor development and drug resistance in non-small cell lung cancer (NSCLC). Methods Western blot and RT-PCR were used to compare the clusterin expression at protein level and mRNA level in Anip973/CDDP with that in wild Anip973. Flow cytometry was employed to detect and analyze the relationship between clusterin and cell cycle, p53 or Bax. Results Clusterin protein expression levels were significantly higher in those Anip973/CDDP than those in wild Anip973. The p53 expression levels were higher in Anip973/CDDP than in Anip973 (P < 0.01). The expression of Bax showed no significant difference between Anip973 and Anip973/CDDP (P > 0.05). As to drug resistant lung cancer cell lines, Anip973/CDDP had more cells in G0–G1 stage while less cells in S stage or G2–M stage than non-resistant cell line. Conclusion Clusterin is associated with resistance to CDDP in NSCLC. The abnormal expression of clusterin and p53 in Anip973/CDDP indicated that both clusterin and p53 might be involved in drug resistance in NSCLC.
Screening the Drug Sensitivity Genes Related to GEM and CDDP in the Lung Cancer Cell-lines
Chunyu YANG,Zhennan TIAN,Wei LIU,Li CAI
Chinese Journal of Lung Cancer , 2009,
Abstract: Background and objective Screening of small-cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) cell lines with gemcitabine hydrochloride (GEM) and cisplatin (CDDP) related to drug sensitivity gene might clarify the action mechanism of anti-cancer drugs and provide a new clue for overcoming drug resistance and the development of new anti-cancer drugs, and also provide theoretical basis for the clinical treatment of individual. Methods The drug sensitivity of CDDP and GEM in 4 SCLC cell lines and 6 NSCLC cell lines was determined using MTT colorimetric assay, while the cDNA macroarray was applied to detect the gene expression state related to drug sensitivity of 10 lung cancer cell line in 1 291, and the correlation between the two was analysized. Results There were 6 genes showing significant positive correlation (r≥0.632, P < 0.05) with GEM sensitivity; 45 genes positively related to CDDP; another 41 genes related to both GEM and CDDP (r≥± 0.4). Lung cancer with GEM and CDDP sensitivity of two types of drugs significantly related genes were Metallothinein (Signal transduction molecules), Cathepsin B (Organization protease B) and TIMP1 (Growth factor); the GEM, CDDP sensitivity associated genes of lung cancer cell lines mainly distributed in Metallothinein, Cathepsin B, growth factor TIMP1 categories. Conclusion There existed drug-related sensitive genes of GEM, CDDP in SCLC and NSCLC cell lines; of these genes, Metallothinein, Cathepsin B and TIMP1 genes presented a significant positive correlation with GEM drug sensitivity, a significant negative correlation with CDDP drug sensitivity.
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