全文获取类型
收费全文 | 132313篇 |
免费 | 3618篇 |
国内免费 | 1006篇 |
专业分类
136937篇 |
出版年
2022年 | 386篇 |
2021年 | 682篇 |
2020年 | 421篇 |
2019年 | 667篇 |
2018年 | 12435篇 |
2017年 | 11148篇 |
2016年 | 8343篇 |
2015年 | 2135篇 |
2014年 | 1929篇 |
2013年 | 2588篇 |
2012年 | 6724篇 |
2011年 | 15072篇 |
2010年 | 13458篇 |
2009年 | 9555篇 |
2008年 | 11629篇 |
2007年 | 13095篇 |
2006年 | 2011篇 |
2005年 | 2114篇 |
2004年 | 2561篇 |
2003年 | 2497篇 |
2002年 | 2313篇 |
2001年 | 1327篇 |
2000年 | 1102篇 |
1999年 | 897篇 |
1998年 | 498篇 |
1997年 | 483篇 |
1996年 | 384篇 |
1995年 | 380篇 |
1994年 | 307篇 |
1993年 | 364篇 |
1992年 | 612篇 |
1991年 | 585篇 |
1990年 | 509篇 |
1989年 | 481篇 |
1988年 | 389篇 |
1987年 | 385篇 |
1986年 | 348篇 |
1985年 | 409篇 |
1984年 | 386篇 |
1983年 | 358篇 |
1982年 | 249篇 |
1981年 | 246篇 |
1979年 | 295篇 |
1978年 | 265篇 |
1977年 | 286篇 |
1976年 | 264篇 |
1975年 | 264篇 |
1974年 | 260篇 |
1972年 | 451篇 |
1971年 | 467篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
152.
L. Chaerle F. De Boever M. Van Montagu & D. Van Der Straeten 《Plant, cell & environment》2001,24(1):15-25
Pending cell death was visualized by thermographic imaging in bacterio‐opsin transgenic tobacco plants. Cell death in these plants was characterized by a complex lesion phenotype. Isolated cell death lesions were preceded by a colocalized thermal effect, as previously observed at sites infected by tobacco mosaic virus (TMV) ( Chaerle et al. 1999 Nature Biotechnology 17, 813–816). However, in most cases, a coherent front of higher temperature, trailed by cell death, initiated at the leaf base and expanded over the leaf lamina. In contrast to the homogenous thermal front, cell death was first visible close to the veins, and subsequently appeared as discrete spots on the interveinal tissue, as cell death spread along the veins. Regions with visible cell death had a lower temperature because of water evaporation from damaged cells. In analogy with previous observations on the localized tobacco–TMV interaction ( Chaerle et al. 1999 ), the kinetics of thermographic and continuous gas exchange measurements indicated that stomatal closure preceded tissue collapse. Localized spontaneous cell death could also be presymptomatically visualized in the Arabidopsis lsd2 mutant. 相似文献
153.
154.
155.
Background
Arsenic contamination is widespread throughout the world and this toxic metalloid is known to cause cancers of organs such as liver, kidney, skin, and lung in human. In spite of a recent surge in arsenic related studies, we are still far from a comprehensive understanding of arsenic uptake, detoxification, and sequestration in plants. Crambe abyssinica, commonly known as 'abyssinian mustard', is a non-food, high biomass oil seed crop that is naturally tolerant to heavy metals. Moreover, it accumulates significantly higher levels of arsenic as compared to other species of the Brassicaceae family. Thus, C. abyssinica has great potential to be utilized as an ideal inedible crop for phytoremediation of heavy metals and metalloids. However, the mechanism of arsenic metabolism in higher plants, including C. abyssinica, remains elusive. 相似文献156.
A cholinergic proteolipid fraction (i.e. a hydrophobic lipoprotein) was separated from the of the cow, using affinity chromatography with the lipophilic gel Sephadex LH-20 and p-phenyltrimethylamonium as the active group. High affinity binding studies showed that only the specific fraction, desorbed after an acetylcholine (or acid) pulse, and corresponding to 0,72% of the proteolipids, is the one that binds the cholinergic ligands. The binding of (3H)atropine and (14C)d-tubocurarine demonstrated that there are 814 picomoles/g fresh tissue of muscarinic sites and only 76 picomoles/g of nicotinic sites. The specific radioactivity for (3H)atropine is 10,000 nmoles/g protein, suggesting a high degree of purification of the specific cholinergic proteolipid. 相似文献
157.
Background
Meiotic prophase is a critical stage in sexual reproduction. Aberrant chromosome recombination during this stage is a leading cause of human miscarriages and birth defects. However, due to the experimental intractability of mammalian gonads, only a very limited number of meiotic genes have been characterized. Here we aim to identify novel meiotic genes important in human reproduction through computational mining of cross-species and cross-sex time-series expression data from budding yeast, mouse postnatal testis, mouse embryonic ovary, and human fetal ovary. 相似文献158.
Kasper Stovgaard Christian Andreetta Jesper Ferkinghoff-Borg Thomas Hamelryck 《BMC bioinformatics》2010,11(1):429
Background
Genome sequencing projects have expanded the gap between the amount of known protein sequences and structures. The limitations of current high resolution structure determination methods make it unlikely that this gap will disappear in the near future. Small angle X-ray scattering (SAXS) is an established low resolution method for routinely determining the structure of proteins in solution. The purpose of this study is to develop a method for the efficient calculation of accurate SAXS curves from coarse-grained protein models. Such a method can for example be used to construct a likelihood function, which is paramount for structure determination based on statistical inference. 相似文献159.
160.
Siddhartha Kumar Bhaumik Manoj Kumar Singh Subir Karmakar Tripti De 《Glycoconjugate journal》2009,26(6):663-673
As compared to cutaneous leishmaniasis, vaccination against visceral leishmaniasis (VL) has received limited attention. In
this study, we demonstrate for the first time that an UDP-Galactose: N-acetylglucosamine β 1–4 galactosyltransferase (GenBank Accession No. EF159943) expressing attenuated LD clonal population (A-LD) is able to confer protection against the experimental challenge with the virulent LD AG83 parasite. A-LD was also effective in established leishmania infection. The vaccinated animals showed both cell mediated
(in vitro T-cell proliferation, and DTH response) and humoral responses (Th1 type). These results demonstrate the potential of the
attenuated clones as an immunotherapeutic and immunoprophylactic agent against visceral leishmaniasis. 相似文献