全文获取类型
收费全文 | 42280篇 |
免费 | 2516篇 |
国内免费 | 6篇 |
出版年
2023年 | 241篇 |
2022年 | 205篇 |
2021年 | 522篇 |
2020年 | 445篇 |
2019年 | 454篇 |
2018年 | 1250篇 |
2017年 | 1056篇 |
2016年 | 1478篇 |
2015年 | 1995篇 |
2014年 | 2020篇 |
2013年 | 2702篇 |
2012年 | 3109篇 |
2011年 | 2835篇 |
2010年 | 1780篇 |
2009年 | 1341篇 |
2008年 | 2202篇 |
2007年 | 2161篇 |
2006年 | 2164篇 |
2005年 | 1795篇 |
2004年 | 1765篇 |
2003年 | 1591篇 |
2002年 | 1512篇 |
2001年 | 1026篇 |
2000年 | 988篇 |
1999年 | 771篇 |
1998年 | 305篇 |
1997年 | 207篇 |
1996年 | 223篇 |
1995年 | 221篇 |
1994年 | 169篇 |
1992年 | 451篇 |
1991年 | 395篇 |
1990年 | 368篇 |
1989年 | 364篇 |
1988年 | 326篇 |
1987年 | 321篇 |
1986年 | 296篇 |
1985年 | 287篇 |
1984年 | 231篇 |
1983年 | 207篇 |
1982年 | 167篇 |
1979年 | 256篇 |
1978年 | 154篇 |
1975年 | 153篇 |
1974年 | 180篇 |
1973年 | 177篇 |
1972年 | 167篇 |
1971年 | 153篇 |
1970年 | 162篇 |
1969年 | 160篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
51.
Acid-catalysed condensation of methyl β-d-glycero-l-manno-heptopyranoside with cyclohexanone yielded an approximately 3:1 mixture of the 2,3:6,7- and 2,3:4,7-di-O-cyclohexylideneheptosides (1 and 2), which could be separated either as their benzoates (3 and 4) or as their methyl ethers (5 and 6). The latter compounds afforded the 4- and 6-methyl ethers (7 and 8) of d-glycero-l-manno-heptitol. 相似文献
52.
53.
54.
55.
56.
57.
Ciliates were collected from a freshwater sulfuretum, Lake Cisó, which is part of a gypsum karstic area whose main feature is Lake Banyoles (Girona, Spain). Chromatium, Lamprocystis and Chlorobium are the major phototrophic sulfur bacteria in Lake Cisó. Blooms of a photosynthetic cryptomonad (up to 5 X 10(5) ind ml-1) were found at the metalimnion. The community of ciliates could be divided in three groups: aerobic, cosmopolitan, genera such as Stentor and Vorticella, in the epilimnion; a large population (up to 10(4) ind ml-1) of Coleps, adapted to low concentrations of both oxygen and sulfide, together with a few individuals of the equally sulfide-tolerant genus Paramecium, in the metalimnion, and anaerobic, true sulfide-loving genera such as Plagiopyla and Metopus, in the hypolimnion, where sulfide concentration was between 0.6 and 1.2 mM. 相似文献
58.
The peptidic sequence (Sarcosine-1-Isoleucine-8)-Angiotensin II has been demonstrated to be an in vitro specific and competitive antagonist of the Angiotensin II action. The present results show it to be a competitive antagonist also in vivo since pA2 values are similar, always reaches a 100% response on increasing the Angiotensin II dose, and when relating log (DR-1) and log dose of agonist, the slope is very near to one (0.925). 相似文献
59.
Piotr Politański Elźbieta Rajkowska Marcin Brodecki Andrzej Bednarek Marek Zmyślony 《Bioelectromagnetics》2013,34(4):333-336
The aim of this study was to investigate the effect of static magnetic fields (SMF) on reactive oxygen species induced by X‐ray radiation. The experiments were performed on lymphocytes from male albino Wistar rats. After exposure to 3 Gy X‐ray radiation (with a dose rate of 560 mGy/min) the measurement of intracellular reactive oxygen species in lymphocytes, using a fluorescent probe, was done before exposure to the SMF, and after 15 min, 1 and 2 h of exposure to the SMF or a corresponding incubation time. For SMF exposure, 0 mT (50 µT magnetic field induction opposite to the geomagnetic field) and 5 mT fields were chosen. The trend of SMF effects for 0 mT was always opposite that of 5 mT. The first one decreased the rate of fluorescence change, while the latter one increased it. Bioelectromagnetics 34:333–336, 2013. © 2012 Wiley Periodicals, Inc. 相似文献
60.
Ca2+ is an important intracellular messenger affecting many diverse processes. In eukaryotic cells, Ca2+ storage is achieved within specific intracellular organelles, especially the endoplasmic/sarcoplasmic reticulum, in which Ca2+ is buffered by specific proteins known as Ca2+ buffers. Ca2+ buffers are a diverse group of proteins, varying in their affinities and capacities for Ca2+, but they typically also carry out other functions within the cell. The wide range of organelles containing Ca2+ and the evidence supporting cross-talk between these organelles suggest the existence of a dynamic network of organellar Ca2+ signaling, mediated by a variety of organellar Ca2+ buffers. 相似文献