全文获取类型
收费全文 | 11152篇 |
免费 | 1153篇 |
国内免费 | 3篇 |
出版年
2023年 | 87篇 |
2022年 | 58篇 |
2021年 | 361篇 |
2020年 | 224篇 |
2019年 | 315篇 |
2018年 | 300篇 |
2017年 | 299篇 |
2016年 | 449篇 |
2015年 | 726篇 |
2014年 | 799篇 |
2013年 | 836篇 |
2012年 | 1070篇 |
2011年 | 955篇 |
2010年 | 579篇 |
2009年 | 485篇 |
2008年 | 648篇 |
2007年 | 586篇 |
2006年 | 501篇 |
2005年 | 450篇 |
2004年 | 400篇 |
2003年 | 321篇 |
2002年 | 244篇 |
2001年 | 155篇 |
2000年 | 119篇 |
1999年 | 96篇 |
1998年 | 57篇 |
1997年 | 53篇 |
1996年 | 44篇 |
1995年 | 48篇 |
1994年 | 50篇 |
1993年 | 43篇 |
1992年 | 74篇 |
1991年 | 69篇 |
1990年 | 84篇 |
1989年 | 73篇 |
1988年 | 79篇 |
1987年 | 62篇 |
1986年 | 65篇 |
1985年 | 57篇 |
1984年 | 38篇 |
1983年 | 40篇 |
1982年 | 30篇 |
1981年 | 22篇 |
1980年 | 24篇 |
1979年 | 24篇 |
1978年 | 21篇 |
1977年 | 25篇 |
1976年 | 23篇 |
1974年 | 20篇 |
1973年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Jessica Hanser 《Curtis's Botanical Magazine》2017,34(4):314-322
This essay reveals a financial dimension to Captain John Blake and his son John Bradby Blake's involvement with China, namely, their participation in financing the Canton trade through predatory loans to Chinese Hong merchants. Widespread predatory lending in Canton led to a financial crisis during the late 1770s, which ruined several British and Chinese merchants. In an effort to recover the money they claimed was owed to them, many British traders, including John Blake, formed a lobby group in London and authorized Britain's first Ambassador to China to negotiate with the Emperor in Beijing on their behalf. 相似文献
2.
Norma L. Pucheu Norma L. Kerber Emilio A. Rivas Néstor Cortez Augusto F. Garcia 《Current microbiology》1997,34(3):155-161
Membranes from in vivo labeled cells of Rhodobacter
capsulatus U43[pTX35] grown photosynthetically carried 60% of
the [32P]-Pi in the “heavy” fraction (HM) after
sucrose gradient sedimentation. Metal-chelating chromatography of either
“heavy” or “light” (LM) membrane fractions rendered
similar Bchl-protein complex profiles after octyl-glucoside treatment,
including most of the radioactivity in the same corresponding elution
fraction (F II). Similar labeling distribution of pigment-protein complexes
was obtained for membranes of dark-grown cells induced by lowering oxygen
tension. Fractions derived from HM showed highly labeled LHIα, whereas the
same complex from LM was essentially [32P]-Pi-free, as revealed
by SDS-PAGE followed by autoradiography. Phospholipid analysis showed a
similar pattern for membranes isolated from cells photosynthetically or
semiaerobically grown, being the most abundant: phosphatidylglycerol,
phosphatidylethanolamine, cardiolipin, and phosphatidylcholine. Part of the
phospholipids from HM comigrated with LHIα during SDS-PAGE and dissociated
from the complexes only after solvent extraction and hydrophobic
chromatography. However, a small amount remained always attached to LHIα,
indicating an unusual strong interaction. These results suggest the existence
of two operationally defined membrane regions carrying LHIα complexes
differing in phosphorylation status and protein-phospholipid interaction.
Received: 10 August 1996 / Accepted: 10 September 1996 相似文献
3.
A rearing system based on a diet gelled with Water-Lock G-400, a synthetic superabsorbent (poly(2-propenamide-co-2-propenoic acid, sodium salt)) (WL), was compared with the standard rearing system (liquid diet suspended in acetate fibers) for the mass production of screwworms, Cochliomyia hominivorax (Coquerel). The WL rearing system yielded 2% heavier pupae, 32% higher egg to pupa survival, and required 54% less diet and 88% less labor than the standard rearing system. Other advantages of the WL system include reduced susceptibility to suboptimal environmental conditions and labor practices and characteristics conducive to centralization and mechanization of rearing procedures. 相似文献
4.
5.
6.
7.
8.
9.
10.