全文获取类型
收费全文 | 1949篇 |
免费 | 13篇 |
专业分类
系统科学 | 23篇 |
教育与普及 | 2篇 |
理论与方法论 | 16篇 |
现状及发展 | 961篇 |
研究方法 | 226篇 |
综合类 | 728篇 |
自然研究 | 6篇 |
出版年
2018年 | 31篇 |
2017年 | 23篇 |
2016年 | 26篇 |
2015年 | 16篇 |
2014年 | 30篇 |
2013年 | 24篇 |
2012年 | 101篇 |
2011年 | 104篇 |
2010年 | 47篇 |
2009年 | 17篇 |
2008年 | 109篇 |
2007年 | 89篇 |
2006年 | 125篇 |
2005年 | 96篇 |
2004年 | 81篇 |
2003年 | 77篇 |
2002年 | 67篇 |
2001年 | 44篇 |
2000年 | 61篇 |
1999年 | 37篇 |
1996年 | 13篇 |
1994年 | 19篇 |
1988年 | 12篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 22篇 |
1984年 | 15篇 |
1983年 | 11篇 |
1982年 | 17篇 |
1981年 | 16篇 |
1980年 | 31篇 |
1979年 | 22篇 |
1978年 | 23篇 |
1977年 | 17篇 |
1976年 | 20篇 |
1975年 | 25篇 |
1973年 | 27篇 |
1972年 | 34篇 |
1971年 | 35篇 |
1970年 | 29篇 |
1969年 | 25篇 |
1968年 | 33篇 |
1967年 | 25篇 |
1966年 | 25篇 |
1965年 | 23篇 |
1964年 | 16篇 |
1963年 | 15篇 |
1961年 | 13篇 |
1956年 | 14篇 |
1947年 | 10篇 |
排序方式: 共有1962条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
Gösta Lindeberg 《Cellular and molecular life sciences : CMLS》1948,4(12):476-477
Zusammenfassung Es wurde die Zugkraft nasser Flachsfasern nach Behandlung mit verschiedenen Chemikalien geprüft. Es wurde gefunden, daß die Mittellamelle der Flachsfaser verschiedene miteinander verbundene Systeme enthält, nämlich Pektin, Lignin und eine im Oxalat unlös iche alkaliempfindliche Komponente. 相似文献
6.
Summary The total amount of bound adenine nucleotides in the coupling factor isolated from spinach chloroplasts and its distribution on AMP, ADP and ATP was analyzed after various incubation conditions. During purification of the coupling factor, the distribution of AMP, ADP and ATP is not altered. The coupling factor from deenergized membranes contains approximately 1 ADP, less than 1 ATP, and small amounts of AMP. During phosphorylation the pattern is changed and ATP becomes the dominant species. When exogenous ADP is lacking, phosphate is readily incorporated into ATP. Inhibition of adenylate kinase by AP5A does not change the distribution pattern of the adenine nucleotides. The distribution pattern shows no integer numbers for the different nucleotides, suggesting that the coupling factor is present in different states in a statistical distribution.Acknowledgment: We thank the Swiss National Foundation for Scientific Research (grant 3.582.79) for generous support. 相似文献
7.
8.
9.
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
10.
In 1986, Brown and Clemmons (Proc. natl Acad. Sci. USA83 (1986) 3321) showed that platelets contain a substance, platelet-derived growth inhibitor (PDGI), that inhibits in vitro endothelial cell replication. Although platelets are rich in transforming grwoth factor (TGF-), PDGI was considered not to be related to TGF-, on the basis of its reported properties (extraction from platelets at neutral pH, binding to heparin-Sepharose). However, we purified PDGI to near homogeneity and showed that on the basis of HPLC retention behavior, in vitro growth inhibitory activities with several cell types, receptor binding, and immunoneutralization of growth inhibitory activity with specific anti-TGF- type 1 antibodies, PDGI is most probably identical with TGF- type 1. 相似文献