全文获取类型
收费全文 | 2701篇 |
免费 | 209篇 |
国内免费 | 2篇 |
专业分类
2912篇 |
出版年
2023年 | 7篇 |
2022年 | 22篇 |
2021年 | 45篇 |
2020年 | 21篇 |
2019年 | 22篇 |
2018年 | 45篇 |
2017年 | 31篇 |
2016年 | 81篇 |
2015年 | 139篇 |
2014年 | 145篇 |
2013年 | 192篇 |
2012年 | 236篇 |
2011年 | 233篇 |
2010年 | 160篇 |
2009年 | 145篇 |
2008年 | 166篇 |
2007年 | 175篇 |
2006年 | 137篇 |
2005年 | 143篇 |
2004年 | 133篇 |
2003年 | 110篇 |
2002年 | 106篇 |
2001年 | 28篇 |
2000年 | 18篇 |
1999年 | 16篇 |
1998年 | 36篇 |
1997年 | 32篇 |
1996年 | 19篇 |
1995年 | 25篇 |
1994年 | 17篇 |
1993年 | 19篇 |
1992年 | 12篇 |
1991年 | 14篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 12篇 |
1984年 | 9篇 |
1983年 | 12篇 |
1982年 | 26篇 |
1981年 | 6篇 |
1980年 | 9篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1977年 | 10篇 |
1976年 | 12篇 |
1975年 | 9篇 |
1971年 | 5篇 |
排序方式: 共有2912条查询结果,搜索用时 0 毫秒
141.
142.
Background
Fine tuning expression of genes is a prerequisite for the strictly human pathogen Neisseria meningitidis to survive hostile growth conditions and establish disease. Many bacterial species respond to stress by using alternative σ factors which, in complex with RNA polymerase holoenzyme, recognize specific promoter determinants. σE, encoded by rpoE (NMB2144) in meningococci, is known to be essential in mounting responses to environmental challenges in many pathogens. Here we identified genes belonging to the σE regulon of meningococci. 相似文献143.
144.
145.
146.
Williams SL Huang J Edwards YJ Ulloa RH Dillon LM Prolla TA Vance JM Moraes CT Züchner S 《Cell metabolism》2010,12(6):675-682
Polg mtDNA mutator mice are important models for investigating the role of acquired mtDNA mutations in aging. Despite extensive study, there remains little consensus on either the etiology of the progeroid phenotype or the mtDNA mutation spectrum induced by disrupted polymerase-γ function. To investigate the latter, we have developed a novel, pragmatic approach we term "Mito-seq," applying next-generation sequencing to enriched, native mtDNA. Regardless of detection parameters we observed an increase of at least two orders of magnitude in the number of mtDNA single nucleotide variants in Polg mutator mice compared to controls. We found no evidence for the accumulation of canonical mtDNA deletions but multimers of the mtDNA control region were identified in brain and heart. These control region multimers (CRMs) contained heterogeneous breakpoints and formed species that excluded the majority of mtDNA genes. CRMs demonstrate that polymerase-γ 3'-5' exonuclease activity is required for preserving mtDNA integrity. 相似文献
147.
148.
149.
150.
R Moriggi Jr HS Di Mauro SC Dias JM Matos MB Urtado NF Camar?o IV Sousa Neto DC Nascimento RA Tibana CO Assump??o J Prestes CB Urtado 《Biology of sport / Institute of Sport》2015,32(4):289-294
Low intensity resistance exercise (RE) with blood flow restriction (BFR) has gained attention in the literature due to the beneficial effects on functional and morphological variables, similar to those observed during traditional RE without BFR, while the effects of BFR on post-exercise hypotension remain unclear. The aim of the present study was to compare the blood pressure (BP) response of trained normotensive individuals to RE with and without BFR. In this cross-over randomized trial, eight male subjects (23.8 ± 4 years, 74 ± 3 kg, 174 ± 4 cm) completed two exercise protocols: traditional RE (3 x 10 repetitions at 70% one-repetition maximum [1-RM]) and low intensity RE (3 x 15 repetitions at 20% 1-RM) with BFR. Blood pressure measurements were performed after 15 min of seated rest (0), immediately after and 10 min, 20 min, 30 min, 40 min, 50 min and 60 min after the experimental sessions. Similar hypotensive effects for systolic BP (SBP) were observed for both protocols (P < 0.05) after exercise, with no differences between groups (P > 0.05) and no statistically significant difference for diastolic BP (P > 0.05). These results suggest that in normotensive trained individuals, both traditional RE and RE with BFR induce hypotension for SBP, which is important to prevent cardiovascular disturbances. 相似文献