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   71099篇
  免费   6431篇
  国内免费   2310篇
耳鼻咽喉   712篇
儿科学   1092篇
妇产科学   805篇
基础医学   12145篇
口腔科学   1079篇
临床医学   4743篇
内科学   12097篇
皮肤病学   1524篇
神经病学   4923篇
特种医学   1016篇
外国民族医学   17篇
外科学   5694篇
综合类   7332篇
现状与发展   11篇
预防医学   2455篇
眼科学   844篇
药学   13892篇
  7篇
中国医学   2461篇
肿瘤学   6991篇
  2024年   60篇
  2023年   1432篇
  2022年   1776篇
  2021年   2856篇
  2020年   2640篇
  2019年   2922篇
  2018年   2955篇
  2017年   2967篇
  2016年   2616篇
  2015年   3024篇
  2014年   4144篇
  2013年   5906篇
  2012年   4112篇
  2011年   4929篇
  2010年   3801篇
  2009年   3817篇
  2008年   3582篇
  2007年   3261篇
  2006年   2968篇
  2005年   2418篇
  2004年   2217篇
  2003年   1868篇
  2002年   1463篇
  2001年   1126篇
  2000年   1041篇
  1999年   837篇
  1998年   728篇
  1997年   737篇
  1996年   610篇
  1995年   710篇
  1994年   600篇
  1993年   520篇
  1992年   438篇
  1991年   415篇
  1990年   368篇
  1989年   311篇
  1988年   245篇
  1987年   256篇
  1986年   238篇
  1985年   414篇
  1984年   470篇
  1983年   295篇
  1982年   351篇
  1981年   266篇
  1980年   241篇
  1979年   197篇
  1978年   147篇
  1977年   137篇
  1976年   147篇
  1975年   98篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Both Gram‐positive and Gram‐negative pathogens or pathogen‐derived components, such as staphylococcal enterotoxins (SEs) and endotoxin (LPS) exposure, activate MyD88‐mediated pro‐inflammatory cellular immunity for host defense. However, dysregulated MyD88‐mediated signaling triggers exaggerated immune response that often leads to toxic shock and death. Previously, we reported a small molecule compound 1 mimicking BB‐loop structure of MyD88 was capable of inhibiting pro‐inflammatory response to SEB exposure in mice. In this study, we designed a dimeric structure compound 4210 covalently linked with compound 1 by a non‐polar cyclohexane linker which strongly inhibited the production of pro‐inflammatory cytokines in human primary cells to SEB (IC50 1–50 μm ) or LPS extracted from Francisella tularensis, Escherichia coli, or Burkholderia mallei (IC50 10–200 μm ). Consistent with cytokine inhibition, in a ligand‐induced cell‐based reporter assay, compound 4210 inhibited Burkholderia mallei or LPS‐induced MyD88‐mediated NF‐kB‐dependent expression of reporter activity (IC50 10–30 μm ). Furthermore, results from a newly expressed MyD88 revealed that 4210 inhibited MyD88 dimer formation which is critical for pro‐inflammatory signaling. Importantly, a single administration of compound 4210 in mice showed complete protection from lethal toxin challenge. Collectively, these results demonstrated that compound 4210 inhibits toxin‐induced inflated pro‐inflammatory immune signaling, thus displays a potential bacterial toxin therapeutic.  相似文献   
992.
Aldose reductase (ALR) enzyme plays a significant role in conversion of excess amount of glucose into sorbitol in diabetic condition, inhibitors of which decrease the secondary complication of diabetes mellitus. To understand the structural interaction of inhibitors with ALR enzyme and develop more effective ALR inhibitors, a series of substituted 5-phenylbenzoate containing N-substituted rhodanine derivatives were synthesized and evaluated for their in vitro ALR inhibitory activity. Docking studies of these compounds were carried out, which revealed that the 5-phenylbenzoate moiety deeply influenced the key π-π stacking while 4-oxo-2-thioxothiazolidines contributed in hydrogen bond interactions. The phenyl ring of benzylidene system occupied in specific pocket constituted from Phe115, Phe122, Leu300 and Cys303 while the rhodanine ring forms a tight net of hydrogen bond with Val47 at anionic binding site of the enzyme. The structural insights obtained from the docking study gave better understanding of rhodanine and macromolecular interaction and will help us in further designing and improving of ALR inhibitory activity of rhodanine analogs.  相似文献   
993.
A novel class of 5,6‐dihydro‐4H‐benzo[d]isoxazol‐7‐ones and 5,6‐dihydro‐4H‐isoxazolo[5,4‐c]pyridin‐7‐ones was designed, synthesized, and assayed to investigate the affinity toward Hsp90 protein. The synthetic route was based on a 1,3‐dipolar cycloaddition of nitriloxides, generated in situ from suitable benzaldoximes, with 2‐bromocyclohex‐2‐enones or 3‐bromo‐5,6‐dihydro‐1H‐pyridin‐2‐ones. Whereas all the compounds bearing a benzamide group on the bicyclic scaffold were devoid of activity, the derivatives carrying a resorcinol‐like fragment showed a remarkable inhibitory effect on Hsp90. Docking calculations were performed to investigate the orientation of the new compounds within the binding site of the enzyme.  相似文献   
994.
995.
In the past decade, the discovery, synthesis, and evaluation for hundreds of CD38 covalent and non‐covalent inhibitors has been reported sequentially by our group and partners; however, a systematic structure‐based guidance is still lacking for rational design of CD38 inhibitor. Here, we carried out a comparative analysis of pharmacophore features and quantitative structure–activity relationships for CD38 inhibitors. The results uncover that the essential interactions between key residues and covalent/non‐covalent CD38 inhibitors include (i) hydrogen bond and hydrophobic interactions with residues Glu226 and Trp125, (ii) electrostatic or hydrogen bond interaction with the positively charged residue Arg127 region, and (iii) the hydrophobic interaction with residue Trp189. For covalent inhibitors, besides the covalent effect with residue Glu226, the electrostatic interaction with residue Arg127 is also necessary, while another hydrogen/non‐bonded interaction with residues Trp125 and Trp189 can also be detected. By means of the SYBYL multifit alignment function, the best CoMFA and CoMSIA with CD38 covalent inhibitors presented cross‐validated correlation coefficient values (q2) of 0.564 and 0.571, and non‐cross‐validated values (r2) of 0.967 and 0.971, respectively. The CD38 non‐covalent inhibitors can be classified into five groups according to their chemical scaffolds, and the residues Glu226, Trp189, and Trp125 are indispensable for those non‐covalent inhibitors binding to CD38, while the residues Ser126, Arg127, Asp155, Thr221, and Phe222 are also important. The best CoMFA and CoMSIA with the F12 analogues presented cross‐validated correlation coefficient values (q2) of 0.469 and 0.454, and non‐cross‐validated values (r2) of 0.814 and 0.819, respectively.  相似文献   
996.
997.
998.
999.
Danshensu, as the effective component of Salvia miltiorrhiza (Danshen), has been widely used in clinical studies for treatment of cardiovascular diseases in China. A new metabolite, 4‐hydroxy‐3‐methoxyphenyllactic acid was isolated from the urine of rats, and its chemical structure was identified by ultraviolet (UV), Infrared Spectroscopy (IR), mass spectrometry (MS) and nuclear magnetic resonance (NMR). Furthermore, a selective and sensitive high performance liquid chromatography‐tandem mass spectrometric (HPLC‐MS/MS) method was developed for the simultaneous quantification of danshensu and its major metabolite, 4‐hydroxy‐3‐methoxyphenyllactic acid, in rat plasma after oral and intravenous administration of danshensu. The separation was performed on a Hypersil Gold C18 column (150 × 2.1 mm i.d., 3.0 µm, Thermo, San jose CA, USA) with gradient elution using a mobile phase composed of methanol and water (containing 0.1% formic acid) at a flow rate of 0.2 mL/min. Linear detection responses were obtained for danshensu and 4‐hydroxy‐3‐methoxyphenyllactic acid ranging from 5 to 10000 ng/mL and 5 to 4000 ng/mL, respectively. The lower limits of quantification (LLOQs) for the two compounds were both 5 ng/mL. The intra‐and inter‐day precision (R.S.D %) were within 5.61% for the two analytes. The average recoveries of the analytes were greater than 72.43%. The method was proved to be stable during all sample storage, preparation and analytic procedures. This method was successfully applied to the pharmacokinetic studies of danshensu and 4‐hydroxy‐3‐methoxyphenyllactic acid after oral and intravenous administration of danshensu in rats.Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
1000.
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