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   56483篇
  免费   2955篇
  国内免费   2290篇
  2023年   736篇
  2022年   1120篇
  2021年   1462篇
  2020年   1488篇
  2019年   1969篇
  2018年   1807篇
  2017年   1198篇
  2016年   1330篇
  2015年   1573篇
  2014年   3203篇
  2013年   3936篇
  2012年   2308篇
  2011年   3218篇
  2010年   2290篇
  2009年   2595篇
  2008年   2932篇
  2007年   2981篇
  2006年   2596篇
  2005年   2298篇
  2004年   2095篇
  2003年   1855篇
  2002年   1639篇
  2001年   1074篇
  2000年   956篇
  1999年   1015篇
  1998年   1066篇
  1997年   868篇
  1996年   799篇
  1995年   759篇
  1994年   702篇
  1993年   595篇
  1992年   554篇
  1991年   480篇
  1990年   416篇
  1989年   393篇
  1988年   337篇
  1987年   350篇
  1986年   284篇
  1985年   397篇
  1984年   587篇
  1983年   466篇
  1982年   489篇
  1981年   412篇
  1980年   393篇
  1979年   368篇
  1978年   279篇
  1977年   221篇
  1976年   192篇
  1974年   165篇
  1973年   150篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
《Cell reports》2020,30(3):739-754.e4
  1. Download : Download high-res image (99KB)
  2. Download : Download full-size image
  相似文献   
32.
《Developmental cell》2020,52(6):714-730.e5
  1. Download : Download high-res image (188KB)
  2. Download : Download full-size image
  相似文献   
33.
The investigation of Encelia canescens afforded, in addition to several known compounds, four new dimeric p-hydroxyacetophenone derivatives, two epimeric chromene dimers and two epimeric mixed dimers of euparin and encecalin. Furthermore, derivatives of tremetone and of encecalin were present. The structures were elucidated hy high field 1H NMR spectroscopy.  相似文献   
34.
35.
A method is described for the subcellular fractionation of goldfish xanthophores. The procedure produces relatively pure fractions of caroteniod droplets, pterinosomes, cytosol and what appears to be plasma membrane. The presence of a distinct pattern of proteins is shown to be associated with the carotenoid droplets. Treatment of the xanthophores with ACTH affects the buoyant density of some carotenoid droplets and stimulates the phosphorylation of a polypeptide associated with the carotenoid droplets.  相似文献   
36.
A tip-focused Ca^2+ gradient is tightly coupled to polarized pollen tube growth, and tip-localized influxes of extracellular Ca^2+ are required for this process. However the molecular identity and regulation of the potential Ca^2+ channels remains elusive. The present study has implicated CNGC18 (cyclic nucleotide-gated channel 18) in polarized pollen tube growth, because its overexpression induced wider and shorter pollen tubes. Moreover, CNGC18 overexpression induced depolarization of pollen tube growth was suppressed by lower extracellular calcium ([Ca^2+]ex). CNGC18-yellow fluorescence protein (YFP) was preferentially localized to the apparent post-Golgi vesicles and the plasma membrane (PM) in the apex of pollen tubes. The PM localization was affected by tip-localized ROP1 signaling. Expression of wild type ROP1 or an active form of ROP1 enhanced CNGC18-YFP localization to the apical region of the PM, whereas expression of RopGAP1 (a ROP1 deactivator) blocked the PM localization. These results support a role for PM-Iocalized CNGC18 in the regulation of polarized pollen tube growth through its potential function in the modulation of calcium influxes.  相似文献   
37.
38.
Nowadays, AT1 receptor (AT1R) antagonists (ARBs) constitute the one of the most prevalent classes of antihypertensive drugs that modulate the renin-angiotensin system (RAS). Their main uses include also treatment of diabetic nephropathy (kidney damage due to diabetes) and congestive heart failure. Towards this direction, our study has been focused on the discovery of novel agents bearing different scaffolds which may evolve as a new class of AT1 receptor antagonists. To fulfill this aim, a combination of computational approaches and biological assays were implemented. Particularly, a pharmacophore model was established and served as a 3D search query to screen the ChEMBL15 database. The reliability and accuracy of virtual screening results were improved by using molecular docking studies. In total, 4 compounds with completely diverse chemical scaffolds from potential ARBs, were picked and tested for their binding affinity to AT1 receptor. Results revealed high nanomolar to micromolar affinity (IC50) for all the compounds. Especially, compound 4 exhibited a binding affinity of 199 nM. Molecular dynamics simulations were utilized in an effort to provide a molecular basis of their binding to AT1R in accordance to their biological activities.  相似文献   
39.
40.
皮肤作为人体最大器官覆盖于全身,能阻挡有害物质的侵入,保护人体内环境稳态,参与人体代谢过程。皮肤损伤、炎症和纤维化等,都会导致皮肤屏障功能的减退,影响正常的生命活动。溶血磷脂酸(lysophosphatidic acid,LPA)是十分活跃的磷脂信号分子,参与多种生理和病理生理过程。LPA是维持体内平衡所必需的生物活性脂质介质,在皮肤中通过不同的信号通路发挥多功能磷脂信使作用。本文综述了皮肤中溶血磷脂酸受体(lysophosphatidic acid receptor,LPA1-6)及其细胞信号通路的作用及机制,综述了LPA在皮肤创面愈合、皮肤瘢痕、皮肤黑色素瘤、硬皮病、皮肤瘙痒、过敏性皮炎、皮肤屏障、皮肤疼痛,皮肤毛发生长中的作用及分子机制,有助于了解LPA在皮肤中的生理和病理生理作用。深入研究LPA的作用机制将有助于挖掘其在皮肤治疗中的作用,开发以LPA为靶点的药物。  相似文献   
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