全文获取类型
收费全文 | 8282篇 |
免费 | 178篇 |
国内免费 | 322篇 |
专业分类
系统科学 | 204篇 |
丛书文集 | 202篇 |
教育与普及 | 105篇 |
理论与方法论 | 23篇 |
现状及发展 | 2011篇 |
研究方法 | 225篇 |
综合类 | 5994篇 |
自然研究 | 18篇 |
出版年
2022年 | 86篇 |
2021年 | 102篇 |
2020年 | 93篇 |
2018年 | 86篇 |
2017年 | 86篇 |
2016年 | 96篇 |
2015年 | 198篇 |
2014年 | 274篇 |
2013年 | 288篇 |
2012年 | 394篇 |
2011年 | 396篇 |
2010年 | 357篇 |
2009年 | 386篇 |
2008年 | 419篇 |
2007年 | 403篇 |
2006年 | 356篇 |
2005年 | 315篇 |
2004年 | 261篇 |
2003年 | 188篇 |
2002年 | 202篇 |
2001年 | 297篇 |
2000年 | 267篇 |
1999年 | 193篇 |
1992年 | 105篇 |
1991年 | 95篇 |
1990年 | 96篇 |
1989年 | 78篇 |
1988年 | 85篇 |
1987年 | 83篇 |
1986年 | 62篇 |
1985年 | 98篇 |
1984年 | 81篇 |
1983年 | 62篇 |
1982年 | 65篇 |
1981年 | 59篇 |
1980年 | 76篇 |
1979年 | 146篇 |
1978年 | 134篇 |
1977年 | 107篇 |
1976年 | 79篇 |
1975年 | 74篇 |
1974年 | 98篇 |
1973年 | 103篇 |
1972年 | 89篇 |
1971年 | 111篇 |
1970年 | 100篇 |
1969年 | 96篇 |
1968年 | 95篇 |
1967年 | 87篇 |
1966年 | 86篇 |
排序方式: 共有8782条查询结果,搜索用时 15 毫秒
961.
Summary Coupling of peptide alkylthiol esters with amino acid derivatives in the presence of pivalic acid or 2-hydroxypyridine proceeds without racemization. A dual role of alkylthiol esters as protective and reactive functions in peptide synthesis was well proved. 相似文献
962.
M Fontes Y Thouveny 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1977,285(16):1541-1544
3H Trp and 14C Lys incorporation in proteins from chromatin of normal and regenerating animals, purified on metrizamide, show that the synthesis of these proteins is different in the two cases. 相似文献
963.
964.
J Breton-Gorius Y Coquin J Guichard 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1975,280(14):1753-1756
The neutrophils and monocytes of two patients with hereditary myeloperoxidase deficiency lacked myeloperoxidase activity as determined by light and electron microscopic cytochemical staining. Using Graham-Karnovsky media, azurophils of neutrophils were devoid of peroxidase whereas all eosinophilic and basophilic granules exhibited normal peroxidase activity. After incubation in alkaline diaminobenzidine media which stains the catalase of microperoxisomes, some small granules were seen to be strongly stained in both immature and mature neutrophils. These small granules were distinct from all other neutrophilic granules which lacked a positive reaction. Only, in the presence of cyanide or aminotriazole, peroxidatic activity was also detected in some ellipsoid azurophils. This observation suggests that these substances activated an oxidase whose nature is discussed. 相似文献
965.
Summary A new norsesquiterpene aldehyde, polygonal and a new sesquiterpene hemiacetal, isodrimeninol having drimane skeleton have been isolated from the seed ofPolygonum hydropiper, and their structures have been established to be1 and5. Polygonal showed pungency and plant growth inhibitory activity. 相似文献
966.
Summary Norlobariol (I) previously described as a synthetic product derived from norlobaridone (II) was isolated as a new metabolite fromXanthoparmelia scabrosa (Tayl.) Hale.Acknowledgment. The authors wish to acknowledge the assistance of Dr D. Galloway in identifying the lichen sample and Dr A.W. Campbell for the microanalytical data. 相似文献
967.
968.
A. Tomoda M. Ida Y. Yoneyama S. Kitajima S. Minakami 《Cellular and molecular life sciences : CMLS》1980,36(12):1345-1347
Summary Human red cells reduced extracellular ferricytochrome c to ferrocytochrome c under various conditions, suggesting that ferricytochrome c reducing systems are present at the outer surface of the red cell membrane. 相似文献
969.
T. Yoshikawa Y. Furukawa Y. Wakamatsu M. Kondo 《Cellular and molecular life sciences : CMLS》1982,38(4):501-502
Summary Immunopotentiators such as BCG, levamisole, PS-K and OK-432 prevent carbon tetrachloride (CCl4) hepatotoxicity, and in spite of exposure to CCl4 the liver tissue levels of thiobarbituric acid (TBA) reactive substances were not increased in rats pretreated with such immunopotentiators. 相似文献