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   3400134篇
  免费   256083篇
  国内免费   6599篇
耳鼻咽喉   49969篇
儿科学   104420篇
妇产科学   92336篇
基础医学   476432篇
口腔科学   100067篇
临床医学   303872篇
内科学   662559篇
皮肤病学   72925篇
神经病学   282566篇
特种医学   133143篇
外国民族医学   1308篇
外科学   512972篇
综合类   78843篇
现状与发展   7篇
一般理论   1353篇
预防医学   267593篇
眼科学   80985篇
药学   254885篇
  8篇
中国医学   6849篇
肿瘤学   179724篇
  2018年   37001篇
  2017年   28149篇
  2016年   30752篇
  2015年   34687篇
  2014年   48195篇
  2013年   73913篇
  2012年   101727篇
  2011年   106998篇
  2010年   61851篇
  2009年   58496篇
  2008年   100802篇
  2007年   107902篇
  2006年   108123篇
  2005年   105426篇
  2004年   101271篇
  2003年   97689篇
  2002年   95924篇
  2001年   151693篇
  2000年   156798篇
  1999年   133059篇
  1998年   37743篇
  1997年   34382篇
  1996年   33506篇
  1995年   32359篇
  1994年   30311篇
  1993年   28183篇
  1992年   106054篇
  1991年   102325篇
  1990年   99328篇
  1989年   96081篇
  1988年   89329篇
  1987年   88003篇
  1986年   83840篇
  1985年   80025篇
  1984年   60558篇
  1983年   51591篇
  1982年   31357篇
  1981年   28062篇
  1979年   57329篇
  1978年   40543篇
  1977年   34724篇
  1976年   32040篇
  1975年   34833篇
  1974年   42338篇
  1973年   40625篇
  1972年   38445篇
  1971年   35807篇
  1970年   33847篇
  1969年   31777篇
  1968年   29260篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
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   
102.
103.
104.
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   
105.
106.
107.
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   
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