全文获取类型
收费全文 | 21141篇 |
免费 | 1783篇 |
国内免费 | 1242篇 |
专业分类
24166篇 |
出版年
2024年 | 113篇 |
2023年 | 183篇 |
2022年 | 425篇 |
2021年 | 656篇 |
2020年 | 524篇 |
2019年 | 606篇 |
2018年 | 571篇 |
2017年 | 530篇 |
2016年 | 704篇 |
2015年 | 1114篇 |
2014年 | 1250篇 |
2013年 | 1460篇 |
2012年 | 1780篇 |
2011年 | 1623篇 |
2010年 | 1105篇 |
2009年 | 956篇 |
2008年 | 1195篇 |
2007年 | 1123篇 |
2006年 | 1018篇 |
2005年 | 916篇 |
2004年 | 844篇 |
2003年 | 799篇 |
2002年 | 770篇 |
2001年 | 466篇 |
2000年 | 427篇 |
1999年 | 360篇 |
1998年 | 213篇 |
1997年 | 158篇 |
1996年 | 156篇 |
1995年 | 113篇 |
1994年 | 110篇 |
1993年 | 98篇 |
1992年 | 155篇 |
1991年 | 128篇 |
1990年 | 131篇 |
1989年 | 137篇 |
1988年 | 99篇 |
1987年 | 102篇 |
1986年 | 111篇 |
1985年 | 106篇 |
1984年 | 77篇 |
1983年 | 70篇 |
1982年 | 61篇 |
1981年 | 56篇 |
1980年 | 52篇 |
1979年 | 79篇 |
1978年 | 65篇 |
1977年 | 48篇 |
1976年 | 50篇 |
1974年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Neurochemical Research - A majority of excitatory synapses in the brain are localized on the dendritic spines. Alterations of spine density and morphology are associated with many neurological... 相似文献
22.
Ming Yi Jay D Horton Jonathan C Cohen Helen H Hobbs Robert M Stephens 《BMC bioinformatics》2006,7(1):30-24
Background
Analysis of High Throughput (HTP) Data such as microarray and proteomics data has provided a powerful methodology to study patterns of gene regulation at genome scale. A major unresolved problem in the post-genomic era is to assemble the large amounts of data generated into a meaningful biological context. We have developed a comprehensive software tool, WholePathwayScope (WPS), for deriving biological insights from analysis of HTP data. 相似文献23.
24.
Netherlands Heart Journal - The residual risk of patients surviving until 1 year after acute coronary syndromes (ACS) is still high, despite secondary prevention. The cornerstone of... 相似文献
25.
Li Wenjun Shen XiuFeng Feng Shenglan Liu Yue Zhao Huiying Zhou Guohao Sang Ming Sun Xiaodong Jiao Rong Liu Fuyuan 《Molecular biology reports》2022,49(9):8197-8207
Molecular Biology Reports - JQ1, a BRD4 inhibitor, first identified its therapeutic role in cancer, has gradually demonstrated a protective effect on the heart in recent years; however, it is... 相似文献
26.
Chi Ho Chan Caleb E. Levar Lori Zacharoff Jonathan P. Badalamenti Daniel R. Bond 《Applied and environmental microbiology》2015,81(20):7178-7186
Metal reduction by members of the Geobacteraceae is encoded by multiple gene clusters, and the study of extracellular electron transfer often requires biofilm development on surfaces. Genetic tools that utilize polar antibiotic cassette insertions limit mutant construction and complementation. In addition, unstable plasmids create metabolic burdens that slow growth, and the presence of antibiotics such as kanamycin can interfere with the rate and extent of Geobacter biofilm growth. We report here genetic system improvements for the model anaerobic metal-reducing bacterium Geobacter sulfurreducens. A motile strain of G. sulfurreducens was constructed by precise removal of a transposon interrupting the fgrM flagellar regulator gene using SacB/sucrose counterselection, and Fe(III) citrate reduction was eliminated by deletion of the gene encoding the inner membrane cytochrome imcH. We also show that RK2-based plasmids were maintained in G. sulfurreducens for over 15 generations in the absence of antibiotic selection in contrast to unstable pBBR1 plasmids. Therefore, we engineered a series of new RK2 vectors containing native constitutive Geobacter promoters, and modified one of these promoters for VanR-dependent induction by the small aromatic carboxylic acid vanillate. Inducible plasmids fully complemented ΔimcH mutants for Fe(III) reduction, Mn(IV) oxide reduction, and growth on poised electrodes. A real-time, high-throughput Fe(III) citrate reduction assay is described that can screen numerous G. sulfurreducens strain constructs simultaneously and shows the sensitivity of imcH expression by the vanillate system. These tools will enable more sophisticated genetic studies in G. sulfurreducens without polar insertion effects or need for multiple antibiotics. 相似文献
27.
Jasreen Kular Jennifer C. Tickner Nathan J. Pavlos Helena M. Viola Tamara Abel Bay Sie Lim Xiaohong Yang Honghui Chen Robert Cook Livia C. Hool Ming Hao Zheng Jiake Xu 《The Journal of biological chemistry》2015,290(3):1729-1742
The maintenance of bone homeostasis requires tight coupling between bone-forming osteoblasts and bone-resorbing osteoclasts. However, the precise molecular mechanism(s) underlying the differentiation and activities of these specialized cells are still largely unknown. Here, we identify choline kinase β (CHKB), a kinase involved in the biosynthesis of phosphatidylcholine, as a novel regulator of bone homeostasis. Choline kinase β mutant mice (flp/flp) exhibit a systemic low bone mass phenotype. Consistently, osteoclast numbers and activity are elevated in flp/flp mice. Interestingly, osteoclasts derived from flp/flp mice exhibit reduced sensitivity to excessive levels of extracellular calcium, which could account for the increased bone resorption. Conversely, supplementation of cytidine 5′-diphosphocholine in vivo and in vitro, a regimen that bypasses CHKB deficiency, restores osteoclast numbers to physiological levels. Finally, we demonstrate that, in addition to modulating osteoclast formation and function, loss of CHKB corresponds with a reduction in bone formation by osteoblasts. Taken together, these data posit CHKB as a new modulator of bone homeostasis. 相似文献
28.
Qing-Yin Wang Hongping Dong Bin Zou Ratna Karuna Kah Fei Wan Jing Zou Agatha Susila Andy Yip Chao Shan Kim Long Yeo Haoying Xu Mei Ding Wai Ling Chan Feng Gu Peck Gee Seah Wei Liu Suresh B. Lakshminarayana CongBao Kang Julien Lescar Francesca Blasco Paul W. Smith Pei-Yong Shi 《Journal of virology》2015,89(16):8233-8244
29.
30.