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   2382541篇
  免费   198808篇
  国内免费   4259篇
耳鼻咽喉   34527篇
儿科学   73071篇
妇产科学   63345篇
基础医学   336517篇
口腔科学   68515篇
临床医学   216063篇
内科学   470728篇
皮肤病学   48394篇
神经病学   201828篇
特种医学   96237篇
外国民族医学   886篇
外科学   362153篇
综合类   56251篇
现状与发展   1篇
一般理论   980篇
预防医学   191162篇
眼科学   55598篇
药学   178165篇
  4篇
中国医学   4438篇
肿瘤学   126745篇
  2018年   24622篇
  2017年   19073篇
  2016年   20871篇
  2015年   23674篇
  2014年   34084篇
  2013年   51458篇
  2012年   69717篇
  2011年   73336篇
  2010年   43120篇
  2009年   41390篇
  2008年   69628篇
  2007年   73952篇
  2006年   74796篇
  2005年   72829篇
  2004年   69949篇
  2003年   67561篇
  2002年   66749篇
  2001年   112507篇
  2000年   116570篇
  1999年   98404篇
  1998年   27951篇
  1997年   25614篇
  1996年   25517篇
  1995年   24679篇
  1994年   23211篇
  1993年   21603篇
  1992年   79415篇
  1991年   76425篇
  1990年   73599篇
  1989年   70856篇
  1988年   65873篇
  1987年   64815篇
  1986年   61352篇
  1985年   58407篇
  1984年   44239篇
  1983年   37671篇
  1982年   22900篇
  1981年   20349篇
  1979年   41309篇
  1978年   28992篇
  1977年   24354篇
  1976年   22841篇
  1975年   23971篇
  1974年   29648篇
  1973年   28047篇
  1972年   26228篇
  1971年   24153篇
  1970年   22753篇
  1969年   21089篇
  1968年   19138篇
排序方式: 共有10000条查询结果,搜索用时 750 毫秒
101.
102.
In the 6th Basic Plan for Long-Term Electricity Supply and Demand (6th BPE) for Korea, for the first time, the environmental costs of air pollution caused by oxides of sulfur (SOx), oxides of nitrogen (NOx), and particulate matters (PM) from power plants were estimated and included. However, several deficiencies in evaluating the environmental costs were found. In this study, (1) the validity of the environmental costs used in the 6th BPE was assessed, (2) a systematic approach was suggested and used to improve the environmental costs estimation, and (3) the sensitivity of the cost of generating electricity to the environmental costs by fuel type with the proposed approach was discussed. We found that the applied environmental costs used in the 6th BPE did not fully include the demographic characteristics of Korea. By applying more realistic parameter values, it was found that the newly estimated environmental cost was about 23 times higher than the cost estimated in the original 6th BPE for coal-fired power plants and about 1.5 times higher for liquefied natural gas (LNG)-fired power plants, suggesting that LNG-fired power plants are more economical if using more realistic environmental costs. Thus, it is critical to check the validity of parameter values when calculating environmental costs.  相似文献   
103.
We present a patient with both dynamic left ventricular outflow tract obstruction and valvular aortic stenosis. The aortic valve was calcified, and velocities and gradients measured by continuous‐wave Doppler met standard criteria for severe aortic stenosis. The increased subvalvular velocities invalidated assumptions of the simplified Bernoulli equation; correction using the longer form of the Bernoulli equation suggested a lower but still significant gradient. The complex shape of the subvalvular spectral Doppler envelope indicated supranormal systolic function and dynamic left ventricular outflow obstruction. Left heart catheterization with an end‐hole catheter was required to determine the subvalvular and valvular components of the obstruction.  相似文献   
104.
105.
Objective: Report efficacy findings from three clinical trials (one phase 2 and two phase 3 [OPUS-1, OPUS-2]) of lifitegrast ophthalmic solution 5.0% for treatment of dry eye disease (DED).

Research design and methods: Three 84-day, randomized, double-masked, placebo-controlled trials. Adults (≥18 years) with DED were randomized (1:1) to lifitegrast 5.0% or matching placebo. Changes from baseline to day 84 in signs and symptoms of DED were analyzed.

Main outcome measures: Phase 2, pre-specified endpoint: inferior corneal staining score (ICSS; 0–4); OPUS-1, coprimary endpoints: ICSS and visual-related function subscale (0–4 scale); OPUS-2, coprimary endpoints: ICSS and eye dryness score (EDS, VAS; 0–100).

Results: Fifty-eight participants were randomized to lifitegrast 5.0% and 58 to placebo in the phase 2 trial; 293 to lifitegrast and 295 to placebo in OPUS-1; 358 to lifitegrast and 360 to placebo in OPUS-2. In participants with mild-to-moderate baseline DED symptomatology, lifitegrast improved ICSS versus placebo in the phase 2 study (treatment effect, 0.35; 95% CI, 0.05–0.65; p?=?0.0209) and OPUS-1 (effect, 0.24; 95% CI, 0.10–0.38; p?=?0.0007). Among more symptomatic participants (baseline EDS ≥40, recent artificial tear use), lifitegrast improved EDS versus placebo in a post hoc analysis of OPUS-1 (effect, 13.34; 95% CI, 2.35–24.33; nominal p?=?0.0178) and in OPUS-2 (effect, 12.61; 95% CI, 8.51–16.70; p?<?0.0001).

Limitations: Trials were conducted over 12 weeks; efficacy beyond this period was not assessed.

Conclusions: Across three trials, lifitegrast improved ICSS in participants with mild-to-moderate baseline symptomatology in two studies, and EDS in participants with moderate-to-severe baseline symptomatology in two studies. Based on the overall findings from these trials, lifitegrast shows promise as a new treatment option for signs and symptoms of DED.  相似文献   
106.
107.
A 17‐year‐old boy presented with recurring severe dermatitis of the face of 5‐months duration that resembled impetigo. He had been treated with several courses of antibiotics without improvement. Biopsy showed changes consistent with allergic contact dermatitis and patch testing later revealed sensitization to benzoyl peroxide, which the patient had been using for the treatment of acne vulgaris.  相似文献   
108.
109.
110.
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