全文获取类型
收费全文 | 1951篇 |
免费 | 10篇 |
国内免费 | 35篇 |
专业分类
系统科学 | 52篇 |
丛书文集 | 14篇 |
教育与普及 | 3篇 |
理论与方法论 | 45篇 |
现状及发展 | 846篇 |
研究方法 | 175篇 |
综合类 | 818篇 |
自然研究 | 43篇 |
出版年
2019年 | 12篇 |
2018年 | 19篇 |
2017年 | 22篇 |
2016年 | 20篇 |
2015年 | 15篇 |
2014年 | 18篇 |
2013年 | 40篇 |
2012年 | 69篇 |
2011年 | 93篇 |
2010年 | 24篇 |
2009年 | 11篇 |
2008年 | 51篇 |
2007年 | 52篇 |
2006年 | 74篇 |
2005年 | 53篇 |
2004年 | 60篇 |
2003年 | 91篇 |
2002年 | 125篇 |
2001年 | 145篇 |
2000年 | 96篇 |
1999年 | 67篇 |
1997年 | 11篇 |
1992年 | 25篇 |
1990年 | 18篇 |
1989年 | 14篇 |
1988年 | 20篇 |
1987年 | 24篇 |
1986年 | 21篇 |
1985年 | 21篇 |
1984年 | 21篇 |
1983年 | 16篇 |
1982年 | 12篇 |
1981年 | 15篇 |
1980年 | 24篇 |
1979年 | 35篇 |
1978年 | 33篇 |
1977年 | 33篇 |
1976年 | 29篇 |
1975年 | 37篇 |
1974年 | 28篇 |
1973年 | 30篇 |
1972年 | 43篇 |
1971年 | 43篇 |
1970年 | 31篇 |
1969年 | 30篇 |
1968年 | 24篇 |
1967年 | 29篇 |
1966年 | 33篇 |
1965年 | 22篇 |
1958年 | 9篇 |
排序方式: 共有1996条查询结果,搜索用时 368 毫秒
1.
2.
3.
Modulation of protein biophysical properties by chemical glycosylation: biochemical insights and biomedical implications 总被引:2,自引:0,他引:2
Solá RJ Rodríguez-Martínez JA Griebenow K 《Cellular and molecular life sciences : CMLS》2007,64(16):2133-2152
Glycosylation constitutes one of the most important posttranslational modifications employed by biological systems to modulate
protein biophysical properties. Due to the direct biochemical and biomedical implications of achieving control over protein
stability and function by chemical means, there has been great interest in recent years towards the development of chemical
strategies for protein glycosylation. Since current knowledge about glycoprotein biophysics has been mainly derived from the
study of naturally glycosylated proteins, chemical glycosylation provides novel insights into its mechanistic understanding
by affording control over glycosylation parameters. This review presents a survey of the effects that natural and chemical
glycosylation have on the fundamental biophysical properties of proteins (structure, dynamics, stability, and function). This
is complemented by a mechanistic discussion of how glycans achieve such effects and discussion of the implications of employing
chemical glycosylation as a tool to exert control over protein biophysical properties within biochemical and biomedical applications.
Received 15 December 2006; received after revision 28 March 2007; accepted 25 April 2007 相似文献
4.
5.
6.
管理系统的最经济控制问题 总被引:1,自引:0,他引:1
依据最经济控制问题的概念及其对无确定性数学模型系统分析存在的局限性,对现代管理系统最经济控制问题,提出了在满足系统基本要求前提下。实现控制功能及品质与控制成本比最佳或最划算的模型定义,并对管理系统的可靠性、ABC管理法、WSR方法论等方面的可靠性成本、运行成本和最佳收益等最经济控制问题进行了研究. 相似文献
7.
J E Landegent N Jansen in de Wal G J van Ommen F Baas J J de Vijlder P van Duijn M Van der Ploeg 《Nature》1985,317(6033):175-177
During the past few years, several methods have been developed for the detection of specific nucleic acid sequences by in situ hybridization using non-radioactive labels such as fluorochromes, cytochemically detectable enzymes and electron-dense markers. These methods are preferable to autoradiography in terms of speed of performance and topological resolution. Their limited sensitivity, however, has so far restricted their use to the detection of repeated sequences. Here we report single gene detection with a procedure using 2-acetylaminofluorene (AAF)-modified probes, immunoperoxidase cytochemistry and reflection-contrast microscopy. We confirmed the autoradiographic data on the localization of the human thyroglobulin (Tg) gene to the distal end of the long arm of chromosome 8. A mixture of cosmid cHT2-derived subclones of the 3' part of the Tg gene, 22.3 kilobase pairs (kbp) in total, was used as a hybridization probe. This procedure can be used to map other unique sequences, if genomic clones are available from which clones with an appropriate amount of inserts can be isolated. 相似文献
8.
Ross P Weinhouse H Aloni Y Michaeli D Weinberger-Ohana P Mayer R Braun S de Vroom E van der Marel GA van Boom JH Benziman M 《Nature》1987,325(6101):279-281
Cellulose is the most abundant renewable carbon resource on earth and is an indispensable raw material for the wood, paper, and textile industries. A model system to study the mechanism of cellulose biogenesis is the bacterium Acetobacter xylinum which produces pure cellulose as an extracellular product. It was from this organism that in vitro preparations which possessed high levels of cellulose synthase activity were first obtained in both membranous and soluble forms. We recently demonstrated that this activity is subject to a complex multi-component regulatory system, in which the synthase is directly affected by an unusual cyclic nucleotide activator enzymatically formed from GTP, and indirectly by a Ca (2+) -sensitive phosphodiesterase which degrades the activator. The cellulose synthase activator (CSA) has now been identified as bis-(3' 5')-cyclic diguanylic acid (5'G3'p5'G3'p) on the basis of mass spectroscopic data, nuclear magnetic resonance analysis and comparison with chemically synthesized material. We also report here on intermediary steps in the synthesis and degradation of this novel circular dinucleotide, which have been integrated into a model for the regulation of cellulose synthesis. 相似文献
9.
J. L. Lacuara S. R. de Barioglio P. P. de Oliva A. S. Bernacchi A. F. de Culasso J. A. Castro B. M. Franke de Cazzulo J. J. Cazzulo 《Cellular and molecular life sciences : CMLS》1991,47(6):612-616
Summary The tricyclic anti-calmodulin drug trifluoperazine (TFP) inhibited growth and motility of epimastigotes ofTrypanosoma cruzi, at concentrations lower than 100 M, and motility and infectivity of the bloodstream trypomastigote form at 200 M. Electron microscopy of TFP-treated epimastigotes showed that the major effect was at the mitochondrial level, with gross swelling and disorganization. The oligomycin-sensitive, mitochondrial ATPase was completely inhibited by 20 M TFP, and the same drug concentration caused a 60% decrease in intracellular ATP content. The results suggest that the trypanocidal effect of TFP may be related more to mitochondrial damage than to the well-known anticalmodulin effect of the drug. 相似文献
10.