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   2501114篇
  免费   206694篇
  国内免费   4780篇
耳鼻咽喉   36137篇
儿科学   76413篇
妇产科学   65808篇
基础医学   352117篇
口腔科学   70331篇
临床医学   228573篇
内科学   494803篇
皮肤病学   50309篇
神经病学   214187篇
特种医学   100358篇
外国民族医学   895篇
外科学   378652篇
综合类   58027篇
现状与发展   4篇
一般理论   1158篇
预防医学   200827篇
眼科学   59128篇
药学   186001篇
  4篇
中国医学   4510篇
肿瘤学   134346篇
  2018年   26554篇
  2017年   20437篇
  2016年   22578篇
  2015年   25747篇
  2014年   37094篇
  2013年   56650篇
  2012年   76785篇
  2011年   81037篇
  2010年   47326篇
  2009年   45445篇
  2008年   77018篇
  2007年   81963篇
  2006年   82486篇
  2005年   80799篇
  2004年   77882篇
  2003年   75128篇
  2002年   74051篇
  2001年   113575篇
  2000年   117399篇
  1999年   99533篇
  1998年   29630篇
  1997年   27011篇
  1996年   26751篇
  1995年   25804篇
  1994年   24228篇
  1993年   22597篇
  1992年   80181篇
  1991年   77169篇
  1990年   74226篇
  1989年   71466篇
  1988年   66496篇
  1987年   65346篇
  1986年   61964篇
  1985年   59117篇
  1984年   45167篇
  1983年   38555篇
  1982年   24138篇
  1981年   21519篇
  1980年   20157篇
  1979年   41928篇
  1978年   29713篇
  1977年   25005篇
  1976年   23421篇
  1975年   24422篇
  1974年   30163篇
  1973年   28452篇
  1972年   26559篇
  1971年   24396篇
  1970年   22964篇
  1969年   21270篇
排序方式: 共有10000条查询结果,搜索用时 484 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.
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   
103.
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.
108.
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   
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