全文获取类型
收费全文 | 51588篇 |
免费 | 17122篇 |
国内免费 | 10篇 |
专业分类
68720篇 |
出版年
2023年 | 178篇 |
2022年 | 273篇 |
2021年 | 777篇 |
2020年 | 2448篇 |
2019年 | 3984篇 |
2018年 | 4275篇 |
2017年 | 4496篇 |
2016年 | 4660篇 |
2015年 | 4886篇 |
2014年 | 4617篇 |
2013年 | 5487篇 |
2012年 | 3573篇 |
2011年 | 3277篇 |
2010年 | 4143篇 |
2009年 | 2726篇 |
2008年 | 2209篇 |
2007年 | 1878篇 |
2006年 | 1803篇 |
2005年 | 1787篇 |
2004年 | 1721篇 |
2003年 | 1692篇 |
2002年 | 1588篇 |
2001年 | 530篇 |
2000年 | 514篇 |
1999年 | 446篇 |
1998年 | 349篇 |
1997年 | 233篇 |
1996年 | 244篇 |
1995年 | 253篇 |
1994年 | 214篇 |
1993年 | 173篇 |
1992年 | 219篇 |
1991年 | 175篇 |
1990年 | 148篇 |
1989年 | 147篇 |
1988年 | 122篇 |
1987年 | 132篇 |
1986年 | 114篇 |
1985年 | 139篇 |
1984年 | 157篇 |
1983年 | 121篇 |
1982年 | 158篇 |
1981年 | 168篇 |
1980年 | 143篇 |
1979年 | 134篇 |
1978年 | 135篇 |
1977年 | 117篇 |
1976年 | 119篇 |
1975年 | 91篇 |
1974年 | 95篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
Maria A. Papathanasopoulos Francois Krier Anne-Marie Revol-Junelles Gerard Lefebvre Jean Pierre Le Caer Alexander von Holy John W. Hastings 《Current microbiology》1997,35(6):331-335
Leuconostoc (Lc.) mesenteroides TA33a produced three bacteriocins with different inhibitory activity spectra. Bacteriocins were purified by adsorption/desorption
from producer cells and reverse phase high-performance liquid chromatography. Leucocin C-TA33a, a novel bacteriocin with a
predicted molecular mass of 4598 Da, inhibited Listeria and other lactic acid bacteria (LAB). Leucocin B-TA33a has a predicted molecular mass of 3466 Da, with activity against Leuconostoc/Weissella (W.) strains, and appears similar to mesenterocin 52B and dextranicin 24, while leucocin A-TA33a, which also inhibited Listeria and other LAB strains, is identical to leucocin A-UAL 187. A survey of other known bacteriocin-producing Leuconostoc/Weissella strains for the presence of the three different bacteriocins revealed that production of leucocin A-, B- and C-type bacteriocins
was widespread. Lc. carnosum LA54a, W. paramesenteroides LA7a, and Lc. gelidum UAL 187-22 produced all three bacteriocins, whereas W. paramesenteroides OX and Lc. carnosum TA11a produced only leucocin A- and B-type bacteriocins.
Received: 11 April 1997 / Accepted: 10 June 1997 相似文献
43.
44.
45.
Four main molecular forms of acetylcholinesterase (AChE) can be solubilized from newborn rat superior cervical ganglia (SCG), homogenized in the presence of a high-ionic-strength, detergent-containing medium. These forms, respectively referred to as 16, 10, 6.5, and 4 S, are characterized by their sedimentation coefficients. Their relative proportions in SCG are notably different in vivo during postnatal maturation, and in culture. The 16-S AChE appears to be mainly neuronal in origin, is maintained in culture independently of original presynaptic in vivo elements, and its cellular pool is not depleted in the presence of tetrodotoxin (TTX). 相似文献
46.
47.
48.
49.
Dielectric spectroscopy is a non-invasive contact technique that permits the in vivo measurement of the specific electrical properties of biological tissue induced by an external electrical field. Permittivity, relaxation time and specific conductivity as a function of corneal hydration (wet weight/dry weight) and temperature were measured in 10 porcine corneas. Variation of tissue hydration has a minor influence on the signal, with a significant variation of the signal being detectable only for relatively dry tissue. A much greater influence was found for temperature, in particular on relaxation times. Dielectric spectroscopy provides us with an opportunity to detect structural, in particular temperature-induced, changes in living tissue. In the frequency range investigated, hydration has only a small influence on the dielectric properties of the tissue. 相似文献
50.
The chemiluminescence (CL) of bis(2,4,6‐trichlorophyenyl) oxalate with hydrogen peroxide in the present of cationic surfactant and gold nanoparticles was studied. The CL emission was obviously enhanced in the presence of surfactant at a suitable concentration, with a synergetic catalysis effect exhibited. Different sizes of gold nanoparticles (15 and 50 nm) showed different effects on CL intensity. Mechanisms of the CL reaction and sensitization effect are discussed. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献