全文获取类型
收费全文 | 2498篇 |
免费 | 134篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 68篇 |
妇产科学 | 54篇 |
基础医学 | 281篇 |
口腔科学 | 20篇 |
临床医学 | 463篇 |
内科学 | 610篇 |
皮肤病学 | 49篇 |
神经病学 | 132篇 |
特种医学 | 28篇 |
外科学 | 269篇 |
综合类 | 22篇 |
预防医学 | 302篇 |
眼科学 | 52篇 |
药学 | 146篇 |
肿瘤学 | 150篇 |
出版年
2024年 | 2篇 |
2023年 | 16篇 |
2022年 | 15篇 |
2021年 | 59篇 |
2020年 | 23篇 |
2019年 | 59篇 |
2018年 | 40篇 |
2017年 | 37篇 |
2016年 | 49篇 |
2015年 | 52篇 |
2014年 | 86篇 |
2013年 | 117篇 |
2012年 | 158篇 |
2011年 | 209篇 |
2010年 | 79篇 |
2009年 | 95篇 |
2008年 | 156篇 |
2007年 | 224篇 |
2006年 | 177篇 |
2005年 | 189篇 |
2004年 | 180篇 |
2003年 | 201篇 |
2002年 | 174篇 |
2001年 | 28篇 |
2000年 | 20篇 |
1999年 | 19篇 |
1998年 | 21篇 |
1997年 | 25篇 |
1996年 | 24篇 |
1995年 | 19篇 |
1994年 | 16篇 |
1993年 | 17篇 |
1992年 | 10篇 |
1991年 | 9篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有2650条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
65.
Lauren S. Blum Holly Dentz Felix Chingoli Benson Chilima Thomas Warne Carla Lee Terri Hyde Jacqueline Gindler James Sejvar Eric D. Mintz 《The American journal of tropical medicine and hygiene》2014,91(4):729-737
Typhoid fever affects an estimated 22 million people annually and causes 216,000 deaths worldwide. We conducted an investigation in August and September 2010 to examine the acceptability of typhoid vaccine in Neno District, Malawi where a typhoid outbreak was ongoing. We used qualitative methods, including freelisting exercises, key informant and in-depth interviews, and group discussions. Respondents associated illness with exposure to “bad wind,” and transmission was believed to be airborne. Typhoid was considered extremely dangerous because of its rapid spread, the debilitating conditions it produced, the number of related fatalities, and the perception that it was highly contagious. Respondents were skeptical about the effectiveness of water, sanitation, and hygiene (WaSH) interventions. The perceived severity of typhoid and fear of exposure, uncertainty about the effectiveness of WaSH measures, and widespread belief in the efficacy of vaccines in preventing disease resulted in an overwhelming interest in receiving typhoid vaccine during an outbreak. 相似文献
66.
Terri T. Ni Jianjun Lu Meiying Zhu Lisette A. Maddison Kelli L. Boyd Lindsey Huskey Bensheng Ju Daniel Hesselson Tao P. Zhong Patrick S. Page-McCaw Didier Y. Stainier Wenbiao Chen 《Proceedings of the National Academy of Sciences of the United States of America》2012,109(38):15389-15394
Conditional mutations are essential for determining the stage- and tissue-specific functions of genes. Here we achieve conditional mutagenesis in zebrafish using FT1, a gene-trap cassette that can be stably inverted by both Cre and Flp recombinases. We demonstrate that intronic insertions in the gene-trapping orientation severely disrupt the expression of the host gene, whereas intronic insertions in the neutral orientation do not significantly affect host gene expression. Cre- and Flp-mediated recombination switches the orientation of the gene-trap cassette, permitting conditional rescue in one orientation and conditional knockout in the other. To illustrate the utility of this system we analyzed the functional consequence of intronic FT1 insertion in supv3l1, a gene encoding a mitochondrial RNA helicase. Global supv311 mutants have impaired mitochondrial function, embryonic lethality, and agenesis of the liver. Conditional rescue of supv311 expression in hepatocytes specifically corrected the liver defects. To test whether the liver function of supv311 is required for viability we used Flp-mediated recombination in the germline to generate a neutral allele at the locus. Subsequently, tissue-specific expression of Cre conditionally inactivated the targeted locus. Hepatocyte-specific inactivation of supv311 caused liver degeneration, growth retardation, and juvenile lethality, a phenotype that was less severe than the global disruption of supv311. Thus, supv311 is required in multiple tissues for organismal viability. Our mutagenesis approach is very efficient and could be used to generate conditional alleles throughout the zebrafish genome. Furthermore, because FT1 is based on the promiscuous Tol2 transposon, it should be applicable to many organisms.High throughput functional genomic and informatic methods have been developed to interrogate the genome and extract functional predictions about many genes at a time. However, careful phenotypic analysis of genetic mutants remains the sine qua non of reductionist biological science. In most experimental organisms, random mutagenesis is the preferred or only mutagenic technique available. DNA alkylating agents, transposable elements, or retroviruses are traditionally used in these organisms. A major limitation of these traditional genetic methods is that they reveal only the earliest and/or most prominent function of a gene as later functions are masked by the earlier phenotype, which is often lethality. To assess later functions, for example in metabolism, aging, or behavior, conditional alleles are required.The development of conditional alleles has proven a boon to studying gene function in temporally or spatially restricted contexts. Traditional conditional alleles disrupt gene function by changing the environment, for example by increasing the temperature. Engineered conditional alleles disrupt gene function by activating a recombination-mediated molecular switch that ablates gene function in one state, but has no functional consequences in the other state (1, 2). In the mouse, engineered conditional alleles can be generated by homologous recombination to insert the molecular switch at defined loci or by retroviral-mediated random insertion of the molecular switch (3, 4). The second approach leverages the orientation-dependent gene disruption of a gene trap and the ability of Flp/Cre recombinases to stably invert the gene trap. By strategically arranging dimers of heterotypical flp- and cre-recombinase binding sites flanking the gene trap, stable inversion is achieved in cis by recombinase-mediated Flip and Excision (FlEx) (5). However, this conditional gene-trap mutagen has not been validated at the organismal level.A distinct advantage of FlEx-based conditional gene-trap mutations is the possibility of stage- and tissue-specific rescue or knockout of the mutated genes. In zebrafish, several gene-trap mutagenesis methods have been developed (6, 7), including the “gene-break” (6, 8) and “FlipTrap” (9) technologies. We set out to test whether the FlEx-based conditional gene-trap mutagenesis approach functions at the organismal level in zebrafish. We show here that a highly mutagenic transposable element can be used for conditional analysis of essential genes. 相似文献
67.
L Fraenkel RL Street V Towle JR O'Leary L Iannone PH Van Ness TR Fried 《Journal of the American Geriatrics Society》2012,60(8):1434-1441
68.
69.
Azeez Butali Satoshi Suzuki Margaret E. Cooper Adela M. Mansilla Karen Cuenco Elizabeth J. Leslie Yasushi Suzuki Teruyuki Niimi Masahiko Yamamoto Gongorjav Ayanga Tudevdorj Erkhembaatar Hiroo Furukawa Kumiko Fujiwawa Hideto Imura Aline L. Petrin Nagato Natsume Terri H. Beaty Mary L. Marazita Jeffery C. Murray M.D. 《American journal of medical genetics. Part A》2013,161(5):965-972
70.
Ahluwalia SC Gross CP Chaudhry SI Ning YM Leo-Summers L Van Ness PH Fried TR 《Journal of general internal medicine》2012,27(5):513-519