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   953篇
  免费   51篇
  1004篇
  2023年   5篇
  2022年   9篇
  2021年   18篇
  2020年   6篇
  2019年   9篇
  2018年   16篇
  2017年   16篇
  2016年   30篇
  2015年   35篇
  2014年   23篇
  2013年   68篇
  2012年   66篇
  2011年   50篇
  2010年   28篇
  2009年   18篇
  2008年   47篇
  2007年   31篇
  2006年   42篇
  2005年   31篇
  2004年   31篇
  2003年   46篇
  2002年   33篇
  2001年   27篇
  2000年   27篇
  1999年   21篇
  1998年   11篇
  1997年   6篇
  1996年   8篇
  1992年   15篇
  1991年   11篇
  1990年   16篇
  1989年   8篇
  1988年   15篇
  1987年   9篇
  1986年   12篇
  1985年   16篇
  1984年   10篇
  1983年   6篇
  1982年   5篇
  1981年   5篇
  1980年   9篇
  1979年   5篇
  1977年   6篇
  1976年   7篇
  1975年   11篇
  1974年   10篇
  1972年   13篇
  1971年   10篇
  1968年   11篇
  1967年   7篇
排序方式: 共有1004条查询结果,搜索用时 31 毫秒
131.
Clr was isolated from human serum by DEAE-cellulose column chromatography in the presence of EDTA. The isolated Clr did not hydrolyze N(alpha)-acetyl-L-arginine methyl ester, unless activated by brief treatment with trypsin [EC 3.4.21.4]. On thecolumn, the C1 esterase inhibitor activity was found to coincide with Clr but not C1s (another subcomponent of the first component) C1r was isolated from the euglobulin fraction of human serum by DEAE-cellulose column chromatograph. On Sephadex G-200 column chromatography, Clr was eluted in the void volume, whereas Clr was eluted in a position corresponding to a molecular weight of 140,000-160,000. The results indicated that, on activation, Clr was converted to an enzyme of lower molecular weight...  相似文献   
132.
A new pentacyclic triterpene acid was isolated from the arial parts of Salvia virgata and its constitution was established as 3β-hydroxy-1-oxo-olean-12-en-28-oic acid and named virgatic acid.  相似文献   
133.
134.
Lima bean protease inhibitor (LBI) can be convalently attached to agarose using the cyanogen bromide activation procedure. The LBI-agarose complex retains full capacity to inhibit chymotrypsin and 30% capacity to inhibit trypsin; the dissociation constant for chymotrypsin bound to LBI-agarose is 3.7 × 10?6m. Bovine pancreatic deoxyribonuclease is contaminated by 3% by weight of chymotrypsin plus chymotrypsinogen. The contaminating proteases may be removed from DNase by sequential reaction with LBI-agarose followed by filtration. The most effective method for the removal of proteases from DNase is chromatography over LBI-agarose. DNase which has been chromatographed over LBI-agarose is at least ten times more stable than DNase prepared by earlier procedures.  相似文献   
135.
The toxic effect of spermidine on normal and transformed cells   总被引:2,自引:0,他引:2  
  相似文献   
136.
Abstract— A sensitive method for measuring γ-aminobutyric acid (GABA) has been developed. This method consists of a combination of the enzymic GABA assay of J akoby and S cott (1959) with the enzymic cycling technique of L owry , P assonneau , S chulz and R ock (1961) and permits the measurement of as little as 2 × 10−14 mol of GABA. Using this method, GABA analyses were made on single isolated nerve cell bodies of different types from the CNS of the cat. Average GABA concentrations in these cell bodies were: spinal ganglion cells, 0.2 m m ; spinal mononeurons, 0.9 m m ; large cells of the ventral part of Deiters' nucleus, 2.7 m m ; large cells of the dorsal part of Deiters' nucleus, 6.3 m m ; cerebellar nuclei cells, 6.0 m m ; cerebellar Purkinje cells, 6.6mM; cerebral Betz cells, 2.5 m m .
The GABA concentrations in the isolated dorsal Deiters' cells were greatly reduced (1.7 m m ) after the removal of the cerebellar vermis while those of the ventral Deiters' cells were unaffected by the denervation. These results suggest that GABA is concentrated within axon terminals, probably of Purkinje neurons, synapsing with the dorsal Deiters' cells. The results of GABA analyses on isolated nerve cells are discussed in relation to the relevant neuronal functions and the possible role of GABA as an inhibitory transmitter.  相似文献   
137.
138.
From a MeOH extract of leaves of Grevillea robusta, seven compounds (1-7) were isolated. One known compound (7) was identified with a benzyl glucoside, icariside F2. The structures of the six of these, named grevillosides A-F (1-6), were elucidated on detailed inspection of one- and two-dimensional NMR spectroscopic data as glucosides of 5-alkylresorcinols.  相似文献   
139.
At the present stage, many papers on MEKC, which include fundamental characteristics and applications, have been available. Because only brief discussion on some aspects of MEKC was described in this article, it is necessary to refer some of those literature when the detailed information is required. Especially, for optimization strategies of MEKC, which was not discussed in this article, theoretical discussions by Foley(85), Vindevogel and Sandra(86), and Khaledi and coworkers(87,88) should be cited, along with the review article(11).  相似文献   
140.
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