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   114019篇
  免费   30848篇
  国内免费   1176篇
耳鼻咽喉   2722篇
儿科学   3004篇
妇产科学   2727篇
基础医学   4298篇
口腔科学   5425篇
临床医学   28328篇
内科学   27768篇
皮肤病学   3697篇
神经病学   13592篇
特种医学   4309篇
外科学   20166篇
综合类   764篇
现状与发展   40篇
一般理论   12篇
预防医学   14694篇
眼科学   2460篇
药学   2052篇
  1篇
中国医学   119篇
肿瘤学   9865篇
  2024年   771篇
  2023年   5157篇
  2022年   1236篇
  2021年   3002篇
  2020年   5610篇
  2019年   2195篇
  2018年   7266篇
  2017年   7585篇
  2016年   8218篇
  2015年   8379篇
  2014年   10915篇
  2013年   13109篇
  2012年   4637篇
  2011年   4498篇
  2010年   7419篇
  2009年   9702篇
  2008年   4366篇
  2007年   3333篇
  2006年   4519篇
  2005年   3027篇
  2004年   2291篇
  2003年   1932篇
  2002年   1837篇
  2001年   2032篇
  2000年   1324篇
  1999年   1897篇
  1998年   2372篇
  1997年   2184篇
  1996年   2220篇
  1995年   1952篇
  1994年   1286篇
  1993年   1094篇
  1992年   915篇
  1991年   792篇
  1990年   629篇
  1989年   679篇
  1988年   656篇
  1987年   501篇
  1986年   490篇
  1985年   459篇
  1984年   432篇
  1983年   453篇
  1982年   372篇
  1981年   338篇
  1980年   261篇
  1979年   137篇
  1978年   195篇
  1977年   196篇
  1976年   171篇
  1974年   142篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Iron deficiency may exacerbate symptoms in the Restless Legs Syndrome (RLS). We investigated the effect of intravenous iron sucrose or placebo on symptoms in patients with RLS and mild to moderate iron deficit. Sixty patients with primary RLS (seven males, age 46 (9) years, S‐ferritin ≤45 μg/L) recruited from a cohort of 231 patients were randomly assigned in a 12‐months double‐blind, multi‐centre study of iron sucrose 1000 mg (n = 29) or saline (n = 31). The primary efficacy variable was the RLS severity scale (IRLS) score at week 11. Median IRLS score decreased from 24 to 7 (week 11) after iron sucrose and from 26 to 17 after placebo (P = 0.123, N.S. for between treatment comparison). The corresponding scores at week 7 were 12 and 20 in the two groups (P = 0.017). Drop out rate because of lack of efficacy at 12 months was 19/31 after placebo and 5/29 patients after iron sucrose (Kaplan–Meier estimate, log rank test P = 0.0006) suggesting an iron induced superior long term RLS symptom control. Iron sucrose was well tolerated. This study showed a lack of superiority of iron sucrose at 11 weeks but found evidence that iron sucrose reduced RLS symptoms both in the acute phase (7 weeks) and during long‐term follow up in patients with variable degree of iron deficiency. Further studies on target patient groups, dosing and dosing intervals are warranted before iron sucrose could be considered for treatment of iron deficient patients with RLS. © 2009 Movement Disorder Society  相似文献   
62.
63.
This study evaluated the effects of tobacco Purchase, Use and Possession (PUP) laws on student perceptions of adolescent tobacco use within towns and schools. Twenty‐four towns were randomly assigned into two conditions, the experimental condition (E PUP) involved efforts to increase both PUP law enforcement and reduce minors' access to commercial sources of tobacco, whereas the control condition (C) focused only on efforts to reduce minors' access to commercial sources of tobacco. A hierarchical linear modeling analytical approach was selected due to the multilevel data and nested design. The present study found that over time, youth in the experimental PUP condition observed less youth tobacco usage at school and in their town, and perceived lower rates of tobacco among their peers at school and among friends than youth in the control condition. The findings suggest that PUP law enforcement might be used to strengthen community norms against youth tobacco use.  相似文献   
64.
65.
66.
67.
68.
69.
70.
PURPOSE: The purpose of this study was to measure spectrophotometrically the color stability of pigmented A-2186 silicone maxillofacial elastomer with 10% by volume of titanium white dry earth opacifier before and after exposure to microwave energy over a simulated 1.5-year period of microwave sterilization. Materials AND METHODS: A-2186 silicone elastomer opacified with titanium white dry earth pigment, pigmented with 5 cosmetic dry earth pigment colors [no pigment (control) group (Pc), red (Pr), yellow ochre (Py), burnt sienna (Po), and a mixture of Pr + Py + Po color group (P3)], was used in this study. Each of the 5 experimental groups consisted of 5 specimens. All specimens were placed in a 250 ml glass beaker filled with 150 ml of water (replenished for each microwave exposure). An exposure of 6 minutes was used 18 times (simulating 1.5 years of microwave sterilization with one 6 minute exposure monthly). Reflectance values were measured by spectrophotometer. Three- and two-way analyses of variance with repeated measures were performed for the color difference (DeltaE*) with the factors of group/color/months, and group/months, respectively. Means were compared by Tukey Honest Significant Difference (HSD) multiple range test calculated at the 0.05 level of significance using SPSS. RESULTS: The trained human eye can detect color changes (DeltaE*) greater than 1.0. Most DeltaE* values of the red pigment group at all intervals and the mixed pigment group at 15- and 18- month intervals increased significantly greater than 1.0 (p < 0.001) compared with the control group. Yellow and burnt sienna groups remained the most color stable over time with DeltaE* values below 0.35. CONCLUSIONS: Lack of color stability of red dry earth pigmented A-2186 silicone maxillofacial elastomers was clinically significant after 12-month exposure to microwave energy as compared with yellow, burnt sienna, and opacified A-2186 dry earth pigments.  相似文献   
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