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   389854篇
  免费   25636篇
  国内免费   2886篇
耳鼻咽喉   5305篇
儿科学   8480篇
妇产科学   10796篇
基础医学   54579篇
口腔科学   12027篇
临床医学   31424篇
内科学   80580篇
皮肤病学   8757篇
神经病学   28077篇
特种医学   14222篇
外国民族医学   82篇
外科学   62213篇
综合类   10165篇
现状与发展   1篇
一般理论   72篇
预防医学   18019篇
眼科学   9805篇
药学   31821篇
  1篇
中国医学   2290篇
肿瘤学   29660篇
  2021年   2843篇
  2019年   3000篇
  2018年   4898篇
  2017年   3655篇
  2016年   3775篇
  2015年   4419篇
  2014年   6173篇
  2013年   8062篇
  2012年   11054篇
  2011年   11308篇
  2010年   6878篇
  2009年   6396篇
  2008年   10242篇
  2007年   11073篇
  2006年   10962篇
  2005年   10002篇
  2004年   9436篇
  2003年   9093篇
  2002年   8712篇
  2001年   28500篇
  2000年   28995篇
  1999年   23832篇
  1998年   5250篇
  1997年   4317篇
  1996年   3741篇
  1995年   3528篇
  1994年   3147篇
  1993年   2885篇
  1992年   16132篇
  1991年   14904篇
  1990年   14213篇
  1989年   14026篇
  1988年   12643篇
  1987年   12105篇
  1986年   11141篇
  1985年   10357篇
  1984年   6940篇
  1983年   5619篇
  1982年   2736篇
  1979年   5514篇
  1978年   3366篇
  1977年   2982篇
  1975年   2651篇
  1974年   3079篇
  1973年   2885篇
  1972年   2839篇
  1971年   2786篇
  1970年   2519篇
  1969年   2550篇
  1968年   2260篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Porocarcinoma is an unusual, locally aggressive and potentially fatal neoplasm. Several cutaneous malignancies have been described in association with porocarcinoma, including squamous cell carcinoma, basal cell carcinoma and tricholemmal carcinoma. Previous reports have indicated that the occurrence of malignant tumours in combination with porocarcinoma is extremely rare, in particular with regard to Bowen disease (BD). We report an uncommon case of porocarcinoma occurring synchronously in a single BD lesion in a 63‐year‐old woman with multiple BD lesions. The clinical and histological findings confirmed this diagnosis.  相似文献   
22.
23.
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   
24.
25.
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   
26.
27.
28.
29.
30.
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