全文获取类型
收费全文 | 10834篇 |
免费 | 1074篇 |
国内免费 | 18篇 |
专业分类
11926篇 |
出版年
2022年 | 65篇 |
2021年 | 105篇 |
2020年 | 61篇 |
2019年 | 100篇 |
2018年 | 115篇 |
2017年 | 134篇 |
2016年 | 226篇 |
2015年 | 355篇 |
2014年 | 428篇 |
2013年 | 509篇 |
2012年 | 726篇 |
2011年 | 720篇 |
2010年 | 505篇 |
2009年 | 442篇 |
2008年 | 666篇 |
2007年 | 702篇 |
2006年 | 628篇 |
2005年 | 661篇 |
2004年 | 652篇 |
2003年 | 649篇 |
2002年 | 661篇 |
2001年 | 123篇 |
2000年 | 95篇 |
1999年 | 120篇 |
1998年 | 195篇 |
1997年 | 132篇 |
1996年 | 116篇 |
1995年 | 118篇 |
1994年 | 120篇 |
1993年 | 111篇 |
1992年 | 90篇 |
1991年 | 89篇 |
1990年 | 73篇 |
1989年 | 85篇 |
1988年 | 81篇 |
1987年 | 75篇 |
1986年 | 81篇 |
1985年 | 78篇 |
1984年 | 93篇 |
1983年 | 91篇 |
1982年 | 105篇 |
1981年 | 115篇 |
1980年 | 106篇 |
1979年 | 64篇 |
1978年 | 61篇 |
1977年 | 47篇 |
1976年 | 61篇 |
1974年 | 51篇 |
1973年 | 46篇 |
1972年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
The gorgoniid Eugorgia is exclusively an eastern Pacific genus. It has a wide geographic and bathymetric range of distribution, found from California to Perú and extends down to 65 m deep. Two new species are herein described. The morphological characters were analyzed and illustrated by light and scanning electron microscopy. Eugorgia beebei
sp. n. can be distinguished by its white, ascending, sparse colony growth. Eugorgia mutabilis
sp. n. can be distinguished by its white colony that changes color after collection, and the conspicuous sharp-crested disc sclerites. From a morphological point of view the new species are related to the daniana-group, the rubens-group and the siedenburgae-group of Eugorgia; their affiliations, and the proposal of a new group are discussed. These new species increases the number of species in the genus to 15, and contribute to the knowledge of the eastern Pacific octocoral biodiversity. 相似文献
3.
Background
Radial chromosome positioning in interphase nuclei is nonrandom and can alter according to developmental, differentiation, proliferation, or disease status. However, it is not yet clear when and how chromosome repositioning is elicited. 相似文献4.
5.
6.
7.
The lipid composition of swimming spores, cysts and five hour germlings was established. Spores utilized triglycerides first, then phospholipids. Upon encystment all glycolipid components decreased, while in germlings the phospholipids, monoglycerides and sterol esters exhibited a marked increase. 相似文献
8.
Gary Wenk Robert Greenland 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1980,183(3):261-267
A procedure for the determination of norepinephrine and dopamine, based on high-performance liquid chromatography, is evaluated using an electrochemical detector system. The use of an inorganic mobile phase to provide resolution of low retention amines and extend column life is discussed. A high degree of correlation between estimations of endogenous catecholamine levels is reported using both electrochemical and fluorometric detector systems. Inter-assay reproducibility of the extraction method, and sensitivity and linearity of response of the electrochemical detector system are shown to be consistent across trials. The system described is determined to be accurate, sensitive, and reliable over time. 相似文献
9.
10.
John M. Robinson Sylvia A. Larrimore David W. Craft H.E. Heath Gary L. Sloan 《Biochemical and biophysical research communications》1982,109(3):730-737
The extracellular protease, endopeptidase, and hexosaminidase produced by were neither induced nor repressed by amino acids but required a tryptic digest of casein for their production. Catabolite repression of exoenzyme production by glucose was not affected by exogenous cyclic adenosine 3′, 5′-monophosphate but was partially relieved by di- or monobutyryl derivatives of this compound. 相似文献