全文获取类型
收费全文 | 2568篇 |
免费 | 213篇 |
国内免费 | 2篇 |
出版年
2023年 | 13篇 |
2022年 | 18篇 |
2021年 | 52篇 |
2020年 | 35篇 |
2019年 | 44篇 |
2018年 | 42篇 |
2017年 | 51篇 |
2016年 | 71篇 |
2015年 | 119篇 |
2014年 | 122篇 |
2013年 | 127篇 |
2012年 | 160篇 |
2011年 | 187篇 |
2010年 | 101篇 |
2009年 | 85篇 |
2008年 | 156篇 |
2007年 | 148篇 |
2006年 | 118篇 |
2005年 | 130篇 |
2004年 | 92篇 |
2003年 | 91篇 |
2002年 | 88篇 |
2001年 | 33篇 |
2000年 | 42篇 |
1999年 | 32篇 |
1998年 | 21篇 |
1997年 | 16篇 |
1996年 | 25篇 |
1995年 | 22篇 |
1994年 | 20篇 |
1993年 | 10篇 |
1992年 | 39篇 |
1991年 | 33篇 |
1990年 | 35篇 |
1989年 | 28篇 |
1988年 | 30篇 |
1987年 | 21篇 |
1986年 | 19篇 |
1985年 | 32篇 |
1984年 | 17篇 |
1983年 | 21篇 |
1982年 | 14篇 |
1981年 | 14篇 |
1979年 | 24篇 |
1978年 | 9篇 |
1976年 | 9篇 |
1974年 | 10篇 |
1973年 | 14篇 |
1972年 | 9篇 |
1971年 | 8篇 |
排序方式: 共有2783条查询结果,搜索用时 31 毫秒
91.
92.
93.
Faiqah Ramli Mawardi Rahmani Nur Kartinee Kassim Najihah Mohd Hashim Mohd Aspollah Sukari Abdah Md Akim Rusea Go 《Phytochemistry letters》2013,6(4):582-585
Two new diprenylated dihydrochalcones, elastichalcone A 1 and elastichalcone B 2 and three known compounds were isolated from the leaves of Artocarpus elasticus. Their structures were determined by various spectroscopic techniques (UV, IR, MS, 1D-NMR and 2D-NMR). Elastichalcone B 2 and a known compound exhibited good free radical scavenging activity with IC50 values of 11.30 and 11.89 μg/ml, respectively. 相似文献
94.
95.
96.
97.
Wesley L Hung Christine Hwang ShangBang Gao Jyothsna Chitturi Ying Wang Hang Li Jean‐Louis Bessereau Mei Zhen 《The EMBO journal》2013,32(12):1745-1760
A neuronal F‐box protein FSN‐1 regulates Caenorhabditis elegans neuromuscular junction development by negatively regulating DLK‐mediated MAPK signalling. In the present study, we show that attenuation of insulin/IGF signalling also contributes to FSN‐1‐dependent synaptic development and function. The aberrant synapse morphology and synaptic transmission in fsn‐1 mutants are partially and specifically rescued by reducing insulin/IGF‐signalling activity in postsynaptic muscles, as well as by reducing the activity of EGL‐3, a prohormone convertase that processes agonistic insulin/IGF ligands INS‐4 and INS‐6, in neurons. FSN‐1 interacts with, and potentiates the ubiquitination of EGL‐3 in vitro, and reduces the EGL‐3 level in vivo. We propose that FSN‐1 may negatively regulate insulin/IGF signalling, in part, through EGL‐3‐dependent insulin‐like ligand processing. 相似文献
98.
The endosomal sorting complexes required for transport (ESCRT) pathway mediates membrane fission reactions during intraluminal endosomal vesicle formation, budding of HIV-1 and other enveloped viruses, and the final abscission step of cytokinesis in mammals and archaea. Current models hold that ubiquitin-binding ESCRT factors act early in the pathway to regulate factor recruitment and assembly, whereas the late acting ESCRT-III proteins form filaments that draw the membranes together and mediate fission, possibly, in collaboration with VPS4-ATPases. I will discuss our current understanding of the structures and functions of the different ESCRT factors in HIV budding and abscission with a particular focus on our studies aimed at understanding: (1) how ubiquitin regulates ESCRT recruitment during HIV-1 budding and (2) the structures and membrane-binding properties of ESCRT-III subunits and filaments. 相似文献
99.
100.
Timothy H. Monk Daniel J. Buysse Martica Hall Eric A. Nofzinger Wesley K. Thompson Sati A. Mazumdar 《Chronobiology international》2013,30(4):831-841
Compared to younger adults, seniors (≥60 yrs) often adopt a highly regular lifestyle, perhaps as an adaptive response to age‐related changes in their sleep and circadian rhythms. At baseline, diary measures of lifestyle regularity (SRM‐5) were obtained from 104 seniors of three separate groups. Thirty‐three subjects were challenged by spousal bereavement or the need to care for a spouse at home with dementia (Challenged); 33 were suffering from formally diagnosed (DSM‐IV) insomnia (Insomnia); and 38 were healthy, well‐functioning older seniors in the second half of their eighth decade of life or later (Healthy Older). The objective of this study was to determine whether lifestyle regularity increased as a function of age within each of these three senior groups. Overall, age was significantly correlated with SRM‐5 (r=0.41, p<0.001), with the SRM score increasing by 0.67 units/decade. The same was true for the Challenged and Insomnia groups, which also showed a significant correlation between SRM and age (Challenged: r=0.48, p<0.01; Insomnia: r=0.36, p<0.05), though with a slightly faster rate of SRM increase in the Challenged (0.95 units/decade) than Insomnia (0.55 units/decade) group. Perhaps there was no correlation between age and SRM (r=0.07, n.s.) in the Healthy Older group due to the small age range, although this group did have a higher overall SRM score than the other two groups (p<0.01). The study thus confirmed that the previously observed increase in lifestyle regularity over the adult lifespan persists into later life. This may represent an adaptive behavioral response that might be used in future therapeutic approaches. 相似文献