全文获取类型
收费全文 | 117758篇 |
免费 | 9669篇 |
国内免费 | 8081篇 |
出版年
2023年 | 1352篇 |
2022年 | 1587篇 |
2021年 | 5429篇 |
2020年 | 3857篇 |
2019年 | 4832篇 |
2018年 | 4777篇 |
2017年 | 3448篇 |
2016年 | 4952篇 |
2015年 | 7392篇 |
2014年 | 8635篇 |
2013年 | 9214篇 |
2012年 | 10914篇 |
2011年 | 10097篇 |
2010年 | 5880篇 |
2009年 | 5453篇 |
2008年 | 6331篇 |
2007年 | 5572篇 |
2006年 | 4871篇 |
2005年 | 3940篇 |
2004年 | 3359篇 |
2003年 | 2984篇 |
2002年 | 2543篇 |
2001年 | 2157篇 |
2000年 | 1959篇 |
1999年 | 1944篇 |
1998年 | 1083篇 |
1997年 | 1160篇 |
1996年 | 1058篇 |
1995年 | 1000篇 |
1994年 | 910篇 |
1993年 | 740篇 |
1992年 | 988篇 |
1991年 | 822篇 |
1990年 | 689篇 |
1989年 | 551篇 |
1988年 | 457篇 |
1987年 | 366篇 |
1986年 | 326篇 |
1985年 | 353篇 |
1984年 | 262篇 |
1983年 | 220篇 |
1982年 | 143篇 |
1981年 | 79篇 |
1980年 | 78篇 |
1979年 | 92篇 |
1978年 | 69篇 |
1977年 | 58篇 |
1976年 | 68篇 |
1975年 | 63篇 |
1974年 | 75篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
Ji Guo Su Xiao Ming Han Xiao Zhang Yan Xue Hou Jian Zhuo Zhu Yi Dong Wu 《Journal of biomolecular structure & dynamics》2016,34(3):560-571
Protein collective motions play a critical role in many biochemical processes. How to predict the functional motions and the related key residue interactions in proteins is important for our understanding in the mechanism of the biochemical processes. Normal mode analysis (NMA) of the elastic network model (ENM) is one of the effective approaches to investigate the structure-encoded motions in proteins. However, the motion modes revealed by the conventional NMA approach do not necessarily correspond to a specific function of protein. In the present work, a new analysis method was proposed to identify the motion modes responsible for a specific function of proteins and then predict the key residue interactions involved in the functional motions by using a perturbation approach. In our method, an internal coordinate that accounts for the specific function was introduced, and the Cartesian coordinate space was transformed into the internal/Cartesian space by using linear approximation, where the introduced internal coordinate serves as one of the axes of the coordinate space. NMA of ENM in this internal/Cartesian space was performed and the function-relevant motion modes were identified according to their contributions to the specific function of proteins. Then the key residue interactions important for the functional motions of the protein were predicted as the interactions whose perturbation largely influences the fluctuation along the internal coordinate. Using our proposed methods, the maltose transporter (MalFGK2) from E. Coli was studied. The functional motions and the key residue interactions that are related to the channel-gating function of this protein were successfully identified. 相似文献
6.
7.
8.
9.
An experiment was conducted to investigate the effect of phytase transgenic corn (PTC) on intestinal microflora, and the fate of transgenic DNA and protein in the digesta and tissues of broilers. A total of 160 1-day-old Arbor Acres commercial male broilers were randomly assigned to 20 cages (8 chicks per cage) with 10 cages (replicates) for each treatment. Birds were fed with a diet containing either PTC (54.0% during 1–21 days and 61.0% during 22–42 days) or non-transgenic isogenic control corn (CC) for a duration of 42 days. There were no significant differences (P>0.05) between birds fed with the PTC diets and those fed with the CC diets in the quantities of aerobic bacteria, anaerobic bacteria, colibacillus and lactobacilli, or microbial diversities in the contents of ileum and cecum. Transgenic phyA2 DNA was not detected, but phyA2 protein was detected in the digesta of duodenum and jejunum of broilers fed with the PTC diets. Both transgenic phyA2 DNA and protein fragments were not found in the digesta of the ileum and rectum, heart, liver, kidney, and breast or thigh muscles of broilers fed with the PTC diets. It was concluded that PTC had no adverse effect on the quantity and diversity of gut microorganisms; Transgenic phyA2 DNA or protein was rapidly degraded in the intestinal tract and was not transferred to the tissues of broilers. 相似文献
10.
The role of the epidermal growth factor-1 and hydrophobic stack domains of human factor IX in binding to endothelial cells. 总被引:6,自引:0,他引:6
W F Cheung D L Straight K J Smith S W Lin H R Roberts D W Stafford 《The Journal of biological chemistry》1991,266(14):8797-8800
To determine the function and specificity in factor IX of the first epidermal growth factor (EGF)-like domain and the eight-amino acid hydrophobic stack encoded by exon C (residues 39-46), these domains were replaced by the corresponding polypeptide regions of factor X and chimeric proteins were produced in human embryo kidney cells. Both chimeras were activated by factor XIa at a rate similar to plasma factor IX and exhibited calcium-dependent fluorescence quenching similar to plasma factor IX. Both chimeras competed equally for binding to the endothelial cell receptor. Our findings make it unlikely that the first EGF-like domain or the hydrophobic stack of factor IX are responsible for the specific binding of factor IX to its endothelial cell receptor. 相似文献