全文获取类型
收费全文 | 44532篇 |
免费 | 4150篇 |
国内免费 | 4756篇 |
出版年
2024年 | 31篇 |
2023年 | 596篇 |
2022年 | 733篇 |
2021年 | 2085篇 |
2020年 | 1619篇 |
2019年 | 2138篇 |
2018年 | 2011篇 |
2017年 | 1475篇 |
2016年 | 1990篇 |
2015年 | 2867篇 |
2014年 | 3519篇 |
2013年 | 3712篇 |
2012年 | 4431篇 |
2011年 | 3923篇 |
2010年 | 2537篇 |
2009年 | 2425篇 |
2008年 | 2636篇 |
2007年 | 2429篇 |
2006年 | 2013篇 |
2005年 | 1775篇 |
2004年 | 1378篇 |
2003年 | 1303篇 |
2002年 | 1071篇 |
2001年 | 777篇 |
2000年 | 638篇 |
1999年 | 628篇 |
1998年 | 387篇 |
1997年 | 339篇 |
1996年 | 308篇 |
1995年 | 255篇 |
1994年 | 204篇 |
1993年 | 150篇 |
1992年 | 198篇 |
1991年 | 158篇 |
1990年 | 131篇 |
1989年 | 100篇 |
1988年 | 90篇 |
1987年 | 75篇 |
1986年 | 66篇 |
1985年 | 88篇 |
1984年 | 18篇 |
1983年 | 27篇 |
1982年 | 14篇 |
1981年 | 14篇 |
1980年 | 5篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1974年 | 6篇 |
1969年 | 13篇 |
1968年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Bong Jin Kim Kyung Seob Song Hyun-Hee Kong Hee-Jae Cha Meesun Ock 《The Korean journal of parasitology》2014,52(1):85-87
We encountered a patient with heavy Hymenolepis nana infection. The patient was a 44-year-old Korean man who had suffered from chronic hepatitis (type B) for 15 years. A large number of H. nana adult worms were found during colonoscopy that was performed as a part of routine health screening. The parasites were scattered throughout the colon, as well as in the terminal ileum, although the patient was immunocompetent. Based on this study, colonoscopy may be helpful for diagnosis of asymptomatic H. nana infections. 相似文献
2.
3.
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
4.
5.
Protein factors that bind to the murine 2',5'-oligoadenylate synthetase ME-12 gene 5' upstream regulatory region 总被引:1,自引:0,他引:1
The murine 2',5'-oligoadenylate synthetase ME-12 gene regulatory region AB forms six complexes with protein factors in murine BALB/c 3T3 cells as demonstrated by the mobility shift electrophoresis assay under the reaction conditions used. The complexes, designated C1-C6 in order of their decreasing electrophoretic mobility, showed three distinctive specificities with regulatory region AB, element A, and element B as probes or competing DNA: 1) C1 is region AB-specific (this complex did not form with either element A or B used alone or as a mixture); 2) C5 formed both with element A and element B; 3) C2, C3, C4, and C6 formed with element B, but not A. The protein factors that give rise to these complexes show differential DNA binding activities in various buffer solutions at different pH values. The C4-forming protein factor is the interferon (IFN)-alpha/beta-stimulated response factor (ISRF) which shows element B specificity. It preexists in the cytoplasm. ISRF appears to be complexed to an inhibitor (ISRFI) in the cytoplasm and to dissociate from the inhibitor and to translocate into the nucleus upon treatment of cells with IFN-alpha/beta. We propose that IFN-alpha/beta treatment of BALB/c 3T3 can trigger at least two events: 1) loosening of a tight inhibitor-ISRF complex with the release of free ISRF; this may be mediated via phosphorylation of ISRF or ISRFI; 2) translocation of ISRF into the nucleus and binding to the enhancer element B, which results in the activation of 2',5'-oligoadenylate synthetase gene expression. 相似文献
6.
7.
8.
Sun Yan Asghari Mohammadreza Zahedipour-Sheshgelani Pari 《Journal of Plant Growth Regulation》2020,39(2):920-929
Journal of Plant Growth Regulation - Activation of complex metabolic pathways and antioxidant activities is necessary for enhancing quality and health promoting capacity of food crops. Plant growth... 相似文献
9.
10.
Khellil Sefiane 《仿生工程学报(英文版)》2009,6(4):5-6
In the natural world,plants and animals haveevolved over time to best adapt to the environment.Theyinteract very effectively with the surrounding environmentby exchanging energies and mass flow across theircuticles of specific micro structures and functions toachieve perfect energy balance.Such different functionsmay include the limitation of uncontrolled loss of water,protection from solar radiation,micro effect of inducedturbulence on flow drag reduction,defence againstpathogens,changing surface wettability and hydropho- 相似文献