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   2392189篇
  免费   199316篇
  国内免费   4360篇
耳鼻咽喉   34540篇
儿科学   73256篇
妇产科学   63354篇
基础医学   337719篇
口腔科学   68934篇
临床医学   217149篇
内科学   473152篇
皮肤病学   48462篇
神经病学   202425篇
特种医学   96585篇
外国民族医学   886篇
外科学   362728篇
综合类   56314篇
现状与发展   1篇
一般理论   989篇
预防医学   193023篇
眼科学   55722篇
药学   178967篇
  4篇
中国医学   4502篇
肿瘤学   127153篇
  2018年   25154篇
  2017年   19364篇
  2016年   21162篇
  2015年   24014篇
  2014年   34369篇
  2013年   51923篇
  2012年   70584篇
  2011年   74236篇
  2010年   43445篇
  2009年   41573篇
  2008年   70264篇
  2007年   74695篇
  2006年   75362篇
  2005年   73351篇
  2004年   70470篇
  2003年   68025篇
  2002年   67201篇
  2001年   112662篇
  2000年   116764篇
  1999年   98512篇
  1998年   27982篇
  1997年   25624篇
  1996年   25525篇
  1995年   24704篇
  1994年   23215篇
  1993年   21602篇
  1992年   79475篇
  1991年   76466篇
  1990年   73643篇
  1989年   70925篇
  1988年   65906篇
  1987年   64861篇
  1986年   61374篇
  1985年   58468篇
  1984年   44259篇
  1983年   37697篇
  1982年   22919篇
  1981年   20361篇
  1979年   41315篇
  1978年   29005篇
  1977年   24372篇
  1976年   22854篇
  1975年   23989篇
  1974年   29667篇
  1973年   28059篇
  1972年   26237篇
  1971年   24172篇
  1970年   22769篇
  1969年   21105篇
  1968年   19154篇
排序方式: 共有10000条查询结果,搜索用时 187 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.
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   
105.
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