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   12820篇
  免费   1368篇
  国内免费   1396篇
  15584篇
  2024年   37篇
  2023年   203篇
  2022年   498篇
  2021年   709篇
  2020年   568篇
  2019年   657篇
  2018年   653篇
  2017年   484篇
  2016年   611篇
  2015年   821篇
  2014年   943篇
  2013年   971篇
  2012年   1130篇
  2011年   1010篇
  2010年   682篇
  2009年   554篇
  2008年   675篇
  2007年   594篇
  2006年   539篇
  2005年   417篇
  2004年   422篇
  2003年   422篇
  2002年   402篇
  2001年   266篇
  2000年   190篇
  1999年   206篇
  1998年   115篇
  1997年   108篇
  1996年   99篇
  1995年   99篇
  1994年   76篇
  1993年   56篇
  1992年   59篇
  1991年   51篇
  1990年   49篇
  1989年   46篇
  1988年   28篇
  1987年   24篇
  1986年   19篇
  1985年   9篇
  1984年   13篇
  1983年   14篇
  1982年   13篇
  1981年   11篇
  1980年   6篇
  1979年   7篇
  1978年   3篇
  1977年   4篇
  1974年   2篇
  1972年   2篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
Hyperthermic treatment at 43 degrees C suppressed the growth of Ehrlich ascites tumor (EAT) cells in vitro. Incubation of EAT cells at 43 degrees C for as little as 1.5 h totally abolished the transplantability of the tumor. At the same time, the rate of cellular glucose uptake, the density of glucose transporter on the cells as well as the extent of thymidine, uridine and leucine incorporation were significantly reduced.  相似文献   
4.
5.
6.
The chemiluminescence (CL) of bis(2,4,6‐trichlorophyenyl) oxalate with hydrogen peroxide in the present of cationic surfactant and gold nanoparticles was studied. The CL emission was obviously enhanced in the presence of surfactant at a suitable concentration, with a synergetic catalysis effect exhibited. Different sizes of gold nanoparticles (15 and 50 nm) showed different effects on CL intensity. Mechanisms of the CL reaction and sensitization effect are discussed. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
7.
A human umbilical vein endothelial cell cDNA library in lambda gt11 was screened for expression of thrombomodulin antigens with affinity-purified rabbit polyclonal anti-thrombomodulin immunoglobulin G (IgG) and mouse monoclonal anti-human thrombomodulin IgG. Among 7 million recombinant clones screened, 12 were recognized by both antibodies. Two of these, lambda HTm10 and lambda HTm12, were shown to encode thrombomodulin by comparison of the amino acid sequence deduced from the nucleotide sequence to the amino acid sequence determined directly from tryptic peptides of thrombomodulin. Thrombomodulin mRNA was estimated to be 3.7 kilobases in length by Northern blot analysis of endothelial cell and placental poly(A)+ RNA. Thrombomodulin mRNA was not detected in human brain, HepG2 hepatoma cells, or the monocytic U937 cell line. Additional cDNA clones were selected by hybridization with the 1.2-kilobase insert of lambda HTm10. One isolate, lambda HTm15, contained a 3693 base pair cDNA insert with an apparent 5'-noncoding region of 146 base pairs, an open reading frame of 1725 base pairs, a stop codon, a 3'-noncoding region of 1779 base pairs, and a poly(A) tail of 40 base pairs. The cDNA sequence encodes a 60.3-kDa protein of 575 amino acids. The predicted protein sequence includes a signal peptide of approximately 21 amino acids, an amino-terminal ligand-binding domain of approximately 223 amino acids, an epidermal growth factor (EGF) homology region of 236 amino acids, a serine/threonine-rich segment of 34 amino acids, a membrane-spanning domain of 23 amino acids, and a cytoplasmic tail of 38 amino acids. The EGF-homology region consists of six tandemly repeated EGF-like domains.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
8.
We have developed a sensitive and selective radioimmunoassay for porcine/human endothelin (ET1). The assay has a detection limit of 0.62 pg/tube and exhibits no cross-reactivity to atrial natriuretic peptide, arginine vasopressin, or angiotensin II. Procedures were developed for extraction of endothelin from human plasma samples and samples of buffer from endothelial cell incubations using C18 Sep-Pak extraction cartridges. The mean recovery following extraction was approximately 80%. Both bovine and porcine aortic endothelial cells were found to produce immunoreactive endothelin (IR-ET) with porcine cells producing 4.7 +/- 1.1 ng of IR-ET/mg cell protein after 6 hours. Human plasma samples were extracted, assayed and found to contain a mean concentration of 2.0 +/- 0.4 pg/ml of IR-ET.  相似文献   
9.
刘国富  黄孝龙 《遗传学报》1990,17(2):130-135
用聚丙烯酰胺凝胶电泳和紫外光谱法分析非冬眠期喜马拉雅土拨鼠4种组织的乳酸脱氢酶(LDH)同工酶的酶谱及其活力,该鼠骨骼肌酶带的多态分布,可能是潜在的调节基因调控所致。另外,本文还对构象异构体产生的亚带进行了研讨。  相似文献   
10.
不同季节银木叶精油化学成分的研究   总被引:1,自引:0,他引:1  
用毛细管气相色谱-质谱-计算机联用技术、毛细管气相色谱双柱保留指数法和双柱标准品叠加法分析了不同季节银木叶精油化学成分。从分离出来的207—250个色谱峰中,初步鉴定出59个成分,被鉴定成分的总量占精油总组成的94.45—98.92%,其主要成分随采油季节不同而有所不同。  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