全文获取类型
收费全文 | 1225篇 |
免费 | 160篇 |
专业分类
1385篇 |
出版年
2021年 | 10篇 |
2020年 | 9篇 |
2019年 | 20篇 |
2018年 | 20篇 |
2017年 | 19篇 |
2016年 | 27篇 |
2015年 | 39篇 |
2014年 | 41篇 |
2013年 | 59篇 |
2012年 | 59篇 |
2011年 | 67篇 |
2010年 | 47篇 |
2009年 | 37篇 |
2008年 | 45篇 |
2007年 | 58篇 |
2006年 | 47篇 |
2005年 | 45篇 |
2004年 | 48篇 |
2003年 | 40篇 |
2002年 | 43篇 |
2001年 | 35篇 |
2000年 | 33篇 |
1999年 | 29篇 |
1998年 | 13篇 |
1997年 | 10篇 |
1996年 | 11篇 |
1995年 | 16篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 18篇 |
1991年 | 16篇 |
1990年 | 23篇 |
1989年 | 14篇 |
1988年 | 14篇 |
1987年 | 13篇 |
1986年 | 18篇 |
1985年 | 17篇 |
1984年 | 14篇 |
1983年 | 12篇 |
1982年 | 14篇 |
1980年 | 18篇 |
1979年 | 31篇 |
1978年 | 11篇 |
1977年 | 12篇 |
1974年 | 11篇 |
1973年 | 15篇 |
1972年 | 9篇 |
1971年 | 10篇 |
1970年 | 11篇 |
1968年 | 11篇 |
排序方式: 共有1385条查询结果,搜索用时 15 毫秒
81.
Species of Saccharomyces, Arxiozyma, Eremothecium, Hanseniaspora (anamorph Kloeckera), Kazachstania, Kluyveromyces, Pachytichospora, Saccharomycodes, Tetrapisispora, Torulaspora, and Zygosaccharomyces, as well as three related anamorphic species assigned to Candida (C. castellii, C. glabrata, C. humilis), were phylogenetically analyzed from divergence in genes of the rDNA repeat (18S, 26S, ITS), single copy nuclear genes (translation elongation factor 1alpha, actin-1, RNA polymerase II) and mitochondrially encoded genes (small-subunit rDNA, cytochrome oxidase II). Single-gene phylogenies were congruent for well-supported terminal lineages but deeper branches were not well resolved. Analysis of combined gene sequences resolved the 75 species compared into 14 clades, many of which differ from currently circumscribed genera. 相似文献
82.
Bacteria use type IV secretion systems for two fundamental objectives related to pathogenesis--genetic exchange and the delivery of effector molecules to eukaryotic target cells. Whereas gene acquisition is an important adaptive mechanism that enables pathogens to cope with a changing environment during invasion of the host, interactions between effector and host molecules can suppress defence mechanisms, facilitate intracellular growth and even induce the synthesis of nutrients that are beneficial to bacterial colonization. Rapid progress has been made towards defining the structures and functions of type IV secretion machines, identifying the effector molecules, and elucidating the mechanisms by which the translocated effectors subvert eukaryotic cellular processes during infection. 相似文献
83.
Lorch SA Banks BA Christie J Merrill JD Althaus J Schmidt K Ballard PL Ischiropoulos H Ballard RA 《Free radical biology & medicine》2003,34(9):1146-1152
Plasma protein levels of 3-nitrotyrosine and 3-chlorotyrosine were measured by LC-MS/MS at 0 and 72 h after the initiation of inhaled nitric oxide (INO) at 20 ppm in 22 prematurely born infants with clinically documented bronchopulmonary dysplasia. Infants were classified at the time of hospital discharge as either "off mechanical ventilation," "on mechanical ventilation," or "expired/organ failure." These outcomes were tested for association with changes in plasma levels of 3-nitrotyrosine and 3-chlorotyrosine and selected clinical risk factors. Infants whose 3-nitrotyrosine levels decreased over the 72 h period were more likely to wean off of mechanical ventilation (p =.03). There was no significant association between changes in 3-chlorotyrosne levels and outcome. After controlling for other variables, an odds ratio of 8.3 (95% CI: 1.3-54.4) for improved outcomes was observed if the 3-nitrotyrosine levels decreased. These data suggest that nitrative and oxidative stress may be related to the severity of lung disease and, consequentially, the overall outcome in this select group of infants with severe bronchopulmonary dysplasia. 相似文献
84.
85.
Christie B 《BMJ (Clinical research ed.)》2000,320(7246):1361
86.
Taste buds on the dorsal tongue surface are continually bathedin saliva rich in epidermal growth factor (EGF). In the followingexperiment, taste bud number and morphology were monitored followingsubmandibular and sublingual salivary gland removal (sialoadenectomy),to determine if EGF plays a role in the maintenance and formationof taste buds. Adult male rats were divided into four groups:sialoadenectomized (SX, n = 4); sialoadenectomized with EGFreplacement (SX + EGF, n = 5); sham-operated (SH, n = 4); andsham-operated with exogenous EGF (SH + EGF, n = 5). After a3 week recovery, SX + EGF and SH + EGF animals were given 50µg/day EGF in their drinking water for 14 days. At day14, saliva was collected, the animals were killed and the presenceof EGF determined by radioligand-binding assay. Tongues wereremoved and histologically examined for the presence and morphologyof taste buds on fungiform and circumvallate papillae, or immunostainedfor the presence of EGF, TGF 相似文献
87.
88.
Systems genetics reveals a transcriptional network associated with susceptibility in the maize–grey leaf spot pathosystem 下载免费PDF全文
89.
90.