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   78672篇
  免费   6408篇
  国内免费   2728篇
耳鼻咽喉   914篇
儿科学   1461篇
妇产科学   2334篇
基础医学   9018篇
口腔科学   1401篇
临床医学   8542篇
内科学   13022篇
皮肤病学   1508篇
神经病学   4277篇
特种医学   3192篇
外国民族医学   6篇
外科学   9715篇
综合类   8267篇
现状与发展   11篇
一般理论   11篇
预防医学   5584篇
眼科学   1606篇
药学   7169篇
  41篇
中国医学   3282篇
肿瘤学   6447篇
  2024年   170篇
  2023年   724篇
  2022年   1877篇
  2021年   2706篇
  2020年   1873篇
  2019年   1878篇
  2018年   2313篇
  2017年   1950篇
  2016年   1857篇
  2015年   2949篇
  2014年   3680篇
  2013年   4434篇
  2012年   6225篇
  2011年   6176篇
  2010年   4349篇
  2009年   3875篇
  2008年   4834篇
  2007年   4642篇
  2006年   4410篇
  2005年   3879篇
  2004年   3347篇
  2003年   3137篇
  2002年   2672篇
  2001年   2148篇
  2000年   1845篇
  1999年   1425篇
  1998年   566篇
  1997年   473篇
  1996年   428篇
  1995年   390篇
  1994年   366篇
  1993年   249篇
  1992年   715篇
  1991年   587篇
  1990年   531篇
  1989年   492篇
  1988年   428篇
  1987年   431篇
  1986年   360篇
  1985年   303篇
  1984年   232篇
  1983年   198篇
  1982年   128篇
  1981年   128篇
  1980年   109篇
  1979年   213篇
  1978年   161篇
  1977年   103篇
  1976年   110篇
  1975年   102篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
24.
25.
鲍雨婷  王琴  陈金  魏力  郝雅楠 《天津护理》2020,28(6):648-652
目的: 应用文献计量学方法,分析国内外医用粘胶相关性皮肤损伤(Medical adhesive-related skin injuries,MARSI)文献的研究主题和热点。方法: 检索Cochrane Library、PubMed、EMbase、Web of science、sinoMed、CNKI、Wanfang、VIP等数据库MARSI相关文献,检索时限为建库至2019年5月。采用SPSS 22.0 软件进行文献计量分析,利用gCLUTO统计对国内外高频主题词进行聚类分析。结果: 共纳入论文103篇,其中外文文献占总文献量的27.18%,中文文献占总文献量的72.82%。聚类分析将国内外高频主题词聚为4大类,依次为皮肤损伤及损伤类型、相关危险因素、风险评估及风险管理、护理干预措施。结论: MARSI仍是国内外研究的热点,其发病机制研究仍处于探索阶段,目前尚缺乏有效的预防策略,研究领域较局限。在今后的研究中,应加强MARSI预防的研究、注重多学科合作。  相似文献   
26.
The state of the mother''s immune system during pregnancy has an important role in fetal development and disruptions in the balance of this system are associated with a range of neurologic, neuropsychiatric and neurodevelopmental disorders. Epidemiological and clinical reports reveal various clues that suggest a possible association between developmental neuropsychiatric disorders and family history of immune system dysfunction. Over the past three decades, analogous increases have been reported in both the incidence of neurodevelopmental disorders and immune-related disorders, particularly allergy and asthma, raising the question of whether allergic asthma and characteristics of various neurodevelopmental disorders share common causal links. We used a mouse model of maternal allergic asthma to test this novel hypothesis that early fetal priming with an allergenic exposure during gestation produces behavioral deficits in offspring. Mothers were primed with an exposure to ovalbumin (OVA) before pregnancy, then exposed to either aerosolized OVA or vehicle during gestation. Both male and female mice born to mothers exposed to aerosolized OVA during gestation exhibited altered developmental trajectories in weight and length, decreased sociability and increased marble-burying behavior. Moreover, offspring of OVA-exposed mothers were observed to have increased serotonin transporter protein levels in the cortex. These data demonstrate that behavioral and neurobiological effects can be elicited following early fetal priming with maternal allergic asthma and provide support that maternal allergic asthma may, in some cases, be a contributing factor to neurodevelopmental disorders.  相似文献   
27.

Purpose

The purpose of this study was to evaluate trends in demographics and outcomes of pediatric breast cancer in a United States population-based cohort.

Methods

The Surveillance, Epidemiology, and End Results (SEER) database was utilized to identify all pediatric patients with malignant breast tumors between 1973 and 2014. Analysis was performed using Stata Statistical Software version 13.1. Associations between categorical variables were made using X2 test. Log-rank test was used for univariate survival analysis. Kaplan–Meier analysis investigated five-year survival rates across several variables. Adjusted analysis was performed using a Cox Proportional-Hazards regression.

Results

134 patients with breast malignancies were identified. Carcinoma was the most prevalent histology (48.5%), followed by fibroepithelial tumors (FETs) (35.1%), and sarcoma (14.2%). FETs were twice as common in black compared to nonblack patients (56.3% vs. 29.0%, p?<?0.01). Analyzing histology by stage revealed that 100% of FETs were early stage disease (p?<?0.0001). 46.7% of the tumors tested were ER/PR negative, more than twice as many compared to the published adult estimate of 20.0%. Unadjusted survival analysis revealed worse survival for patients with adenocarcinoma/sarcomas, advanced stage, and high grade disease, without a survival difference between races.

Conclusion

Breast cancer remains a rare malignancy among pediatric patients. Although black patients were found to have more noncarcinomatous tumors with less advanced disease, this did not confer a survival advantage.

Type of study

Retrospective cohort study.

Level of evidence

Level III.  相似文献   
28.
Vitamin D is responsible for multiple metabolic functions in humans. Rickets are the most common disease caused by vitamin D deficiency. It is caused by poor calcium intake resulting in poor serum-ionized calcium. The purpose of this study is to develop a rapid, sensitive, and feasible method to determine the 25-hydroxy-vitamin D3 (25(OH)D3) levels in blood samples for clinical assessment. In this study, gas chromatography coupled mass spectrometry with trimethylsilyl derivatization (TMS-GC-MS) is the most suitable protocol for quantitative analyses of 25(OH)D3. Performance of method was evaluated and compared with liquid chromatography and immunoassay. Method validation has been carried out with plasma specimens. The limit of quantitation of TMS-GC-MS method is 1.5 ppb with good linear correlation. Furthermore, the dietary intake and nutritional status of vegetarian and non-vegetarians in Taiwan were assessed by our validated method. As a result, this vitamin D nutrition survey demonstrates that most Taiwanese people have insufficient vitamin D. Due to dietary habits; the male vegans may have the highest risk of vitamin D deficiency.  相似文献   
29.
Abstract

Cadmium (Cd) as environmental pollutant can induce severe damage, particularly to the testis. This study investigated the effects of Caffeic acid phenethyl ester (CAPE) on testicular dysfunction induced by Cd. Adult mice were intraperitoneally injected with cadmium chloride (CdCl2) with different doses of CAPE pretreatment. After CdCl2 injection, body/testis weight ratio decreased, Cd levels accumulated and zinc levels decreased in testis. Furthermore, Cd intoxication caused a significant increase of oxidative stress levels, antioxidant enzymes activities, and glutathione levels. Interestingly, significant improvements were observed after the administration of CAPE. Our results demonstrated the protective effect of CAPE, linking Cd testicular dysfunction to oxidative stress.  相似文献   
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