全文获取类型
收费全文 | 6398篇 |
免费 | 462篇 |
国内免费 | 25篇 |
专业分类
耳鼻咽喉 | 40篇 |
儿科学 | 225篇 |
妇产科学 | 109篇 |
基础医学 | 773篇 |
口腔科学 | 158篇 |
临床医学 | 526篇 |
内科学 | 1563篇 |
皮肤病学 | 72篇 |
神经病学 | 257篇 |
特种医学 | 109篇 |
外国民族医学 | 1篇 |
外科学 | 660篇 |
综合类 | 375篇 |
一般理论 | 2篇 |
预防医学 | 796篇 |
眼科学 | 179篇 |
药学 | 602篇 |
中国医学 | 71篇 |
肿瘤学 | 367篇 |
出版年
2023年 | 49篇 |
2022年 | 146篇 |
2021年 | 301篇 |
2020年 | 147篇 |
2019年 | 199篇 |
2018年 | 184篇 |
2017年 | 154篇 |
2016年 | 171篇 |
2015年 | 206篇 |
2014年 | 230篇 |
2013年 | 302篇 |
2012年 | 536篇 |
2011年 | 474篇 |
2010年 | 260篇 |
2009年 | 225篇 |
2008年 | 343篇 |
2007年 | 350篇 |
2006年 | 333篇 |
2005年 | 326篇 |
2004年 | 287篇 |
2003年 | 254篇 |
2002年 | 201篇 |
2001年 | 144篇 |
2000年 | 130篇 |
1999年 | 116篇 |
1998年 | 45篇 |
1997年 | 37篇 |
1996年 | 37篇 |
1995年 | 30篇 |
1994年 | 19篇 |
1993年 | 24篇 |
1992年 | 71篇 |
1991年 | 55篇 |
1990年 | 41篇 |
1989年 | 58篇 |
1988年 | 37篇 |
1987年 | 26篇 |
1986年 | 38篇 |
1985年 | 36篇 |
1984年 | 28篇 |
1983年 | 23篇 |
1982年 | 16篇 |
1981年 | 13篇 |
1979年 | 27篇 |
1978年 | 16篇 |
1977年 | 12篇 |
1975年 | 17篇 |
1974年 | 12篇 |
1973年 | 16篇 |
1972年 | 12篇 |
排序方式: 共有6885条查询结果,搜索用时 62 毫秒
111.
Jinsheng Dong Antonio Munoz Sarah E. Kolitz Adesh K. Saini Wen-ling Chiu Hafsa Rahman Jon R. Lorsch Alan G. Hinnebusch 《Genes & development》2014,28(5):502-520
Eukaryotic initiator tRNA (tRNAi) contains several highly conserved unique sequence features, but their importance in accurate start codon selection was unknown. Here we show that conserved bases throughout tRNAi, from the anticodon stem to acceptor stem, play key roles in ensuring the fidelity of start codon recognition in yeast cells. Substituting the conserved G31:C39 base pair in the anticodon stem with different pairs reduces accuracy (the Sui− [suppressor of initiation codon] phenotype), whereas eliminating base pairing increases accuracy (the Ssu− [suppressor of Sui−] phenotype). The latter defect is fully suppressed by a Sui− substitution of T-loop residue A54. These genetic data are paralleled by opposing effects of Sui− and Ssu− substitutions on the stability of methionylated tRNAi (Met-tRNAi) binding (in the ternary complex [TC] with eIF2-GTP) to reconstituted preinitiation complexes (PICs). Disrupting the C3:G70 base pair in the acceptor stem produces a Sui− phenotype and also reduces the rate of TC binding to 40S subunits in vitro and in vivo. Both defects are suppressed by an Ssu− substitution in eIF1A that stabilizes the open/POUT conformation of the PIC that exists prior to start codon recognition. Our data indicate that these signature sequences of tRNAi regulate accuracy by distinct mechanisms, promoting the open/POUT conformation of the PIC (for C3:G70) or destabilizing the closed/PIN state (for G31:C39 and A54) that is critical for start codon recognition. 相似文献
112.
113.
114.
Xiao-Qin Li Ya-Nan Song Su-Juan Wang Khalid Rahman 《Journal of Asian natural products research》2018,20(5):399-411
Over the past decades, a number of phytochemicals have been reported to possess potent pharmacological effects. Saikosaponins represent a group of oleanane derivatives, usually as glucosides, which are commonly found in medicinal plants Bupleurum spp., which have been used as traditional Chinese medicine for more than 1,000 years in China. Emerging evidence suggests that saikosaponins have many pharmacological effects, including sedation, anticonvulsant, antipyretic, antiviral, immunity, anti-inflammation, antitumor properties, protecting liver and kidney and so on. The present review provides a comprehensive summary and analysis of the pharmacological properties of saikosaponins, supporting the potential uses of saikosaponins as a medicinal agent. 相似文献
115.
116.
117.
118.
Nurul Absar M. Mashiur Rahman Masud Kamal Naziba Siddique Mantazul Islam Chowdhury 《Journal of radiation research》2014,55(6):1075-1080
Radioactivity in the soil of a tea garden in the Fatickchari area in Chittagong, Bangladesh, was measured using a high-resolution HPGe detector. The soil samples were collected from depths of up to 20 cm beneath the soil surface. The activity concentrations of naturally occurring 238U and 232Th were observed to be in the range of 27 ± 7 to 53 ± 8 Bq kg−1 and 36 ± 11 to 72 ± 11 Bq kg−1, respectively. The activity concentration of 40K ranged from 201 ± 78 to 672 ± 81 Bq kg−1, and the highest activity of fallout 137Cs observed was 10 ± 1 Bq kg−1. The average activity concentration observed for 238U was 39 ± 8 Bq kg−1, for 232Th was 57 ± 11 Bq kg−1, for 40K was 384 ± 79 Bq kg−1 and for 137Cs was 5 ± 0.5 Bq kg−1. The radiological hazard parameters (representative level index, radium equivalent activity, outdoor and indoor dose rates, outdoor and indoor annual effective dose equivalents, and radiation hazard index) were calculated from the radioactivity in the soil. 相似文献
119.
Epigenome‐wide DNA methylation changes with development of arsenic‐induced skin lesions in Bangladesh: A case–control follow‐up study
下载免费PDF全文
![点击此处可从《Environmental and molecular mutagenesis》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Wei Jie Seow Molly L. Kile Andrea A. Baccarelli Wen‐Chi Pan Hyang‐Min Byun Golam Mostofa Quazi Quamruzzaman Mahmuder Rahman Xihong Lin David C. Christiani 《Environmental and molecular mutagenesis》2014,55(6):449-456
Studies have found an association between aberrant DNA methylation and arsenic‐induced skin lesions. However, little is known about DNA methylation changes over time in people who develop arsenic‐induced skin lesions. We sought to investigate epigenome‐wide changes of DNA methylation in people who developed arsenic‐induced skin lesions in a 10‐year period. In 2009–2011, we conducted a follow‐up study of 900 skin lesion cases and 900 controls and identified 10 people who developed skin lesions since a baseline survey in 2001–2003. The 10 cases (“New Cases”) were matched with 10 controls who did not have skin lesions at baseline or follow‐up (“Persistent Controls”). Drinking water and blood samples were collected, and skin lesion was diagnosed by the same physician at both time points. We measured DNA methylation in blood using Infinium HumanMethylation450K BeadChip, followed by quantitative validation using pyrosequencing. Two‐sample t‐tests were used to compare changes in percent methylation between New Cases and Persistent Controls. Six CpG (cytosine‐phosphate‐guanine) sites with greatest changes of DNA methylation over time among New Cases were further validated with a correlation of 93% using pyrosequencing. One of the validated CpG site (cg03333116; change of %methylation was 13.2 in New Cases versus ?0.09 in Persistent Controls; P < 0.001) belonged to the RHBDF1 gene, which was previously reported to be hypermethylated in arsenic‐exposed cases. We examined DNA methylation changes with the development of arsenic‐induced skin lesions over time but nothing was statistically significant given the small sample size of this exploratory study and the high dimensionality of data. Environ. Mol. Mutagen. 55:449–456, 2014. © 2014 Wiley Periodicals, Inc. 相似文献
120.