首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   271165篇
  免费   25850篇
  国内免费   20191篇
耳鼻咽喉   2058篇
儿科学   2362篇
妇产科学   3037篇
基础医学   33461篇
口腔科学   4413篇
临床医学   38969篇
内科学   39425篇
皮肤病学   2440篇
神经病学   15341篇
特种医学   9675篇
外国民族医学   201篇
外科学   26162篇
综合类   44955篇
现状与发展   75篇
一般理论   27篇
预防医学   16161篇
眼科学   8361篇
药学   28693篇
  394篇
中国医学   16265篇
肿瘤学   24731篇
  2025年   87篇
  2024年   3681篇
  2023年   5962篇
  2022年   11932篇
  2021年   14516篇
  2020年   11410篇
  2019年   9477篇
  2018年   9793篇
  2017年   8708篇
  2016年   8262篇
  2015年   12354篇
  2014年   15135篇
  2013年   12658篇
  2012年   18907篇
  2011年   21645篇
  2010年   13127篇
  2009年   10149篇
  2008年   13430篇
  2007年   13462篇
  2006年   13681篇
  2005年   13930篇
  2004年   8275篇
  2003年   7662篇
  2002年   6439篇
  2001年   5748篇
  2000年   6457篇
  1999年   7211篇
  1998年   4760篇
  1997年   4777篇
  1996年   3713篇
  1995年   3533篇
  1994年   2904篇
  1993年   1970篇
  1992年   2218篇
  1991年   1849篇
  1990年   1572篇
  1989年   1338篇
  1988年   1139篇
  1987年   993篇
  1986年   748篇
  1985年   610篇
  1984年   351篇
  1983年   214篇
  1982年   115篇
  1981年   126篇
  1980年   85篇
  1979年   91篇
  1965年   1篇
  1962年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Two new secoiridoid glucosides, ilexpublignoside (1), pubzenoside (2), and a new lignan, ilexlignan B (3), along with seven known compounds (4–10) were isolated from the roots of Ilex pubescens for the first time. Their chemical structures were elucidated on the basis of extensive spectroscopic methods, including IR, UV, HR-ESI–MS, CD, NMR experiments, as well as comparison with the reported data.  相似文献   
52.
Background: In this study, we coordinated a network meta‐analysis to establish the efficacy and safety of different agents used in the treatment of hyperphosphatemia patients with chronic kidney disease. Methods: PubMed, CNKI, and Embase were systematically searched to retrieve relevant studies. Outcomes were presented by mean differences, odds ratios, and corresponding 95% credible intervals for continuous outcomes and binary outcomes, respectively. Each therapy was ranked according to the value of surface under the cumulative ranking curve. Consistencies between direct and indirect comparisons were assessed with a node‐splitting plot. Results: In terms of efficacy end points (including levels of serum phosphate, serum calcium, serum intact parathyroid hormone, and serum calcium × phosphorus product), all 7 kinds of agents outperformed or performed at least equally to placebo, with iron‐based phosphate‐binding agents being potentially the most effective. As for safety end points (including mortality, adverse events, and all‐cause discontinuation), almost all agents were equivalent in term of mortality and all‐cause discontinuation except in the comparison between iron‐based phosphate‐binding agents and placebo. Meanwhile, iron‐based phosphate‐binding agents colestilan and nicotinic acid performed poorly compared with placebo in terms of adverse events. Furthermore, iron‐based phosphate‐binding agents were potentially the safest agents followed sequentially by calcium‐based phosphate‐binding agents and placebo. Conclusion: Iron‐based phosphate‐binding agents were the preferable agents when considering efficacy and safety simultaneously.  相似文献   
53.
54.
55.
56.
ABSTRACT

Despite significant health benefits of regular physical activity, over 60 percent of college women do not meet recommended physical activity guidelines to promote their health and health-related quality of life (HRQoL), a comprehensive construct including physical and psychosocial health functioning. The major purpose of this study was to examine the influences of individual (e.g., self-efficacy, enjoyment), social (e.g., family and friend support), and physical environmental factors (e.g., crime safety) on college women’s physical activity and HRQoL. Participants were 235 (Mean age = 21.0 years) college women from a public research university located in the southwest region of the United States. They completed validated surveys assessing their perceptions of physical activity, HRQoL, and social ecological factors during the spring semester of 2012. The findings of three multiple linear regressions, entering individual factors first, followed by social and physical environmental factors, revealed that self-efficacy and crime safety were significantly related to physical activity. For HRQoL-physical functioning, significant factors were self-efficacy, enjoyment, and crime safety. Enjoyment was the only factor related to HRQoL-psychosocial functioning. These findings indicated that physical activity professionals need to foster safe environments, enhance self-efficacy, and provide enjoyable activities to promote college women’s physical activity and HRQoL.  相似文献   
57.
Context: MOTILIPERM was prepared as a mixture of extracts of three medicinal herbs [roots of Morinda officinalis How (Rubiaceae), outer scales of Allium cepa L. (Liliaceae) and seeds of Cuscuta chinensis Lamark (Convolvulaceae)].

Objective: To investigate the role of reactive oxygen species (ROS)-based endoplasmic reticulum (ER) stress in a rat model of varicocele and the therapeutic efficacy of MOTILIPERM in this model.

Materials and methods: Sixty male rats were divided into five experimental groups: a normal control group (CTR?+?vehicle), a control group administered MOTILIPERM 200?mg/kg (CTR?+?M 200), a varicocele-induced control group (VC?+?vehicle) and two varicocele-induced groups administered MOTILIPERM 100 (VC?+?M 100) or 200 (VC?+?M 200) mg/kg for 4 weeks. Testis weights were recorded and serums were assayed for hormone concentrations. Tissues were subjected to semen analysis, histopathology, analyses of ER response protein expression levels and oxidative stress were assessed by measuring ROS, reactive nitrogen species (RNS), malondialdehyde (MDA) level and ratios of total glutathione (GSH)/oxidized GSH (GSSG).

Results: MOTILIPERM treatment of varicocele-induced groups significantly increased left testis weight, testosterone level, sperm motility, count and spermatogenic cell density. ER-response protein expression levels were dose-dependently decreased in VC?+?M 200 group compared with VC?+?vehicle group. MOTILIPERM treatment also decreased MDA and ROS/RNS level but increased GSH/GSSG ratio.

Discussion and conclusions: This study suggests that ROS-related ER stress may play a major role in varicocele-induced infertility and MOTILIPERM, a novel compound targeting ROS-based ER stress, may be therapeutically useful in treatment of varicocele, or as a supplement for the treatment of infertility.  相似文献   
58.
59.
60.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号