首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   336篇
  免费   7篇
化学   244篇
晶体学   6篇
力学   10篇
数学   19篇
物理学   64篇
  2023年   1篇
  2022年   7篇
  2021年   14篇
  2020年   8篇
  2019年   6篇
  2018年   16篇
  2017年   10篇
  2016年   11篇
  2015年   12篇
  2014年   21篇
  2013年   31篇
  2012年   27篇
  2011年   29篇
  2010年   18篇
  2009年   12篇
  2008年   17篇
  2007年   13篇
  2006年   8篇
  2005年   11篇
  2004年   5篇
  2003年   6篇
  2002年   10篇
  2001年   3篇
  2000年   5篇
  1999年   3篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1994年   4篇
  1993年   3篇
  1992年   2篇
  1991年   3篇
  1988年   2篇
  1987年   3篇
  1986年   2篇
  1985年   1篇
  1984年   7篇
  1982年   3篇
  1981年   1篇
  1980年   1篇
  1979年   2篇
  1974年   1篇
排序方式: 共有343条查询结果,搜索用时 15 毫秒
21.
Naturally occurring phytochemicals with reported antibacterial activity were screened for their ability to inhibit the bacterial cell division protein Escherichia coli FtsZ. Among the representative compounds, coumarins inhibit the GTPase and polymerization activities of this protein effectively. Further screening with ten coumarin analogs we identified two promising candidates, scopoletin and daphnetin. The former is found to inhibit the GTPase activity of the protein in a noncompetitive manner. Docking of these coumarins with the modeled protein indicate that they bind to T7 loop, which is different from the GTP-binding site (active site), thereby supporting the experimental data. Lowest binding energy is obtained with scopoletin. 3D QSAR indicates the need for groups such as hydroxyl, diethyl, or dimethyl amino in the 7th carbon for enhanced activity. None of the coumarins exhibited cytotoxicity against NIH/3T3 and human embryonic kidney cell lines. The length of Bacillus subtilis increases in the presence of these compounds probably due to the lack of septum formation. Results of this study indicate the role of coumarins in halting the first step of bacterial cell division process.  相似文献   
22.
A series of benzenesulfonamide-appended [1,2,3]-triazole hybrids was synthesized by using [3 + 2] cycloaddition of primary, secondary, and tertiary sulfonamide azides with various phenoxymethylacetylenes under click reaction conditions. After structural characterization, the compounds were subjected to in-silico absorption, distribution, metabolism, excretion and toxicity (ADMET) screening to evaluate their drug-likeness and other pharmacokinetic parameters. Furthermore, their in vitro antiplasmodial potential was assessed against Plasmodium falciparum (3D7) strain, and some of the synthesized compounds displayed promising antimalarial potency. On cytotoxicity evaluation using MTT cell viability assay, the most active candidate N-(4,6-dimethylpyridin-2-yl)-4-(4-(4-nitrophenoxy)methyl)-1H-[1,2,3]-triazol-1-yl)benzenesulfonamide ( 14 ; IC50 6.2 μg/mL) demonstrated CC50 7.5 μg/mL against human hepatocarcinoma (HUH-7) cells.  相似文献   
23.
Journal of Thermal Analysis and Calorimetry - The solar collector (reflector and receiver) is the primary device being used in the concentrating solar power technologies for tapping the solar...  相似文献   
24.
25.

Abstract  

5-Lipoxygenase inhibitor 3-O-acetyl-9,11-dehydro-β-boswellic acid was detected in the extract of Boswellia serrata gum resulting from unstable 11-hydroxy precursor. It was reported more potent than other Boswellic acids in its inhibition of 5-Lipoxygenase. Here, we report the method of conversion of 3-acetoxy-β-boswellic acid to 3-O-acetyl-9,11-dehydro-β-boswellic acid, and the crystal structure of later. This compound crystallizes in orthorhombic space group P212121 with cell parameters of a = 12.726(1) ?, b = 16.597(1) ?, c = 27.332(2) ?, α = β = γ = 90°, V = 5772.7(5) ?3, D c = 1.143 Mg/m3, and Z = 8. The X-ray structure investigation indicates that the rings A, B, D and E are exhibit chair and the ring C adopts a distorted half chair conformation. The conformational difference of the two structures in the arrangement is due to crystal packing of 3-O-acetyl-9,11-dehydro-β-boswellic acid. The molecular packing is stabilized by C–H···O and O–H···O types of hydrogen bonding interactions.  相似文献   
26.
27.
28.
29.
Polymer electrolyte films prepared from poly (methyl methacrylate) and LiAsF6 with different concentrations of plasticizer (DBP) are described. The formation of polymer-salt complexes has been confirmed by XRD and FTIR spectral studies. The temperature dependence of the conductivity of the polymer films obeys the VTF relation. Values of conductivities of the polymer complexes are presented and discussed.  相似文献   
30.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号