全文获取类型
收费全文 | 669篇 |
免费 | 33篇 |
出版年
2023年 | 3篇 |
2022年 | 9篇 |
2021年 | 15篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 9篇 |
2017年 | 6篇 |
2016年 | 18篇 |
2015年 | 29篇 |
2014年 | 27篇 |
2013年 | 38篇 |
2012年 | 39篇 |
2011年 | 36篇 |
2010年 | 25篇 |
2009年 | 11篇 |
2008年 | 26篇 |
2007年 | 14篇 |
2006年 | 27篇 |
2005年 | 34篇 |
2004年 | 27篇 |
2003年 | 25篇 |
2002年 | 19篇 |
2001年 | 6篇 |
2000年 | 11篇 |
1999年 | 14篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 19篇 |
1991年 | 9篇 |
1990年 | 16篇 |
1989年 | 16篇 |
1988年 | 6篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 16篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 4篇 |
1975年 | 7篇 |
1974年 | 5篇 |
1947年 | 3篇 |
排序方式: 共有702条查询结果,搜索用时 15 毫秒
61.
Corrigendum to Wagner et al.: Natural soil microbes alter flowering phenology and the intensity of selection on flowering time in a wild Arabidopsis relative 下载免费PDF全文
62.
63.
64.
The environment is currently undergoing changes at both global (e.g., climate change) and local (e.g., tourism, pollution, habitat modification) scales that have the capacity to affect the viability of animal and plant populations. Many of these changes, such as human disturbance, have an anthropogenic origin and therefore may be mitigated by management action. To do so requires an understanding of the impact of human activities and changing environmental conditions on population dynamics. We investigated the influence of human activity on important life history parameters (reproductive rate, and body condition, and growth rate of neonate pups) for California sea lions (Zalophus californianus) in the Gulf of California, Mexico. Increased human presence was associated with lower reproductive rates, which translated into reduced long-term population growth rates and suggested that human activities are a disturbance that could lead to population declines. We also observed higher body growth rates in pups with increased exposure to humans. Increased growth rates in pups may reflect a density dependent response to declining reproductive rates (e.g., decreased competition for resources). Our results highlight the potentially complex changes in life history parameters that may result from human disturbance, and their implication for population dynamics. We recommend careful monitoring of human activities in the Gulf of California and emphasize the importance of management strategies that explicitly consider the potential impact of human activities such as ecotourism on vertebrate populations. 相似文献
65.
66.
67.
68.
Bamford MJ Bailey N Davies S Dean DK Francis L Panchal TA Parr CA Sehmi S Steadman JG Takle AK Townsend JT Wilson DM 《Bioorganic & medicinal chemistry letters》2005,15(14):3407-3411
The novel imidazo[4,5-c]pyridine 1,2,5-oxadiazol-3-yl template affords an excellent start point for identification of inhibitors of a number of protein kinases. Here we report on its optimisation for mitogen and stress-activated protein kinase-1 (MSK-1) inhibitory activity, and selectivity over other kinases. 相似文献
69.
70.
N-methyl-d-aspartate receptor (NMDAR) stimulation activates many downstream mechanisms involved in both cell survival and cell death. The manner in which the NMDAR regulates one of these pathways, the p38 mitogen-activated protein kinase (p38) pathway, is currently unknown. In the present study, we have defined a developmental-, concentration-, and time-dependent phosphorylation and subsequent dephosphorylation of p38. In cultured hippocampal neurons 7-8 days in vitro (DIV7-8), NMDAR stimulation leads to a concentration-dependent increase in p38 phosphorylation (phospho-p38). However, in more mature neurons (>DIV17) application of NMDA produces concentration-dependent effects, such that low concentrations result in sustained increases in phospho-p38 levels, and high concentrations dephosphorylate p38 within 5 min. Conantokin G, an antagonist of NR1/2A/2B and NR1/2B receptors, inhibits p38 phosphorylation, while NR1/2B-specific antagonists prevent the rapid dephosphorylation of p38 without affecting p38 activation. Furthermore, inhibition of calcineurin prevents the activation of p38, whereas inhibition of phosphoinositide 3-kinase (PI3K) prevents the rapid dephosphorylation of p38. Our results support the presence of subtype-dependent pathways regulating p38 activation and deactivation: one involves NR1/2A/2B receptors activating calcineurin and resulting in p38 phosphorylation, and the other utilizes NR1/2B receptors binding to and activating PI3K and leading to the dephosphorylation of p38 in a manner involving both NR1/2A/2B receptor activation and tyrosine phosphorylation of NR2B. The ability of NMDAR subtype-specific mechanisms to regulate p38 has implications for NMDAR-mediated synaptic plasticity, gene regulation, and excitotoxicity. 相似文献