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   3153598篇
  免费   247196篇
  国内免费   5645篇
耳鼻咽喉   45752篇
儿科学   101352篇
妇产科学   85103篇
基础医学   445571篇
口腔科学   89846篇
临床医学   286420篇
内科学   613997篇
皮肤病学   65676篇
神经病学   260427篇
特种医学   125595篇
外国民族医学   1301篇
外科学   476399篇
综合类   74105篇
现状与发展   2篇
一般理论   1236篇
预防医学   252401篇
眼科学   73747篇
药学   235847篇
  6篇
中国医学   5945篇
肿瘤学   165711篇
  2018年   32461篇
  2017年   24865篇
  2016年   27429篇
  2015年   30971篇
  2014年   44296篇
  2013年   67562篇
  2012年   91737篇
  2011年   97083篇
  2010年   57374篇
  2009年   54824篇
  2008年   92232篇
  2007年   98340篇
  2006年   98990篇
  2005年   96317篇
  2004年   93207篇
  2003年   90215篇
  2002年   88667篇
  2001年   145966篇
  2000年   151162篇
  1999年   128137篇
  1998年   37085篇
  1997年   33617篇
  1996年   33481篇
  1995年   32294篇
  1994年   30266篇
  1993年   28271篇
  1992年   103076篇
  1991年   100169篇
  1990年   96788篇
  1989年   93191篇
  1988年   86301篇
  1987年   85034篇
  1986年   80254篇
  1985年   76772篇
  1984年   58216篇
  1983年   49549篇
  1982年   29815篇
  1981年   26751篇
  1979年   54228篇
  1978年   37977篇
  1977年   32136篇
  1976年   30200篇
  1975年   32101篇
  1974年   39132篇
  1973年   37293篇
  1972年   34769篇
  1971年   31993篇
  1970年   30294篇
  1969年   28031篇
  1968年   25525篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
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   
92.
93.
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   
94.
95.
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   
96.
97.
98.
99.
100.
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