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   1663篇
  免费   84篇
  国内免费   35篇
耳鼻咽喉   16篇
儿科学   32篇
妇产科学   18篇
基础医学   264篇
口腔科学   16篇
临床医学   137篇
内科学   319篇
皮肤病学   27篇
神经病学   97篇
特种医学   170篇
外科学   151篇
综合类   25篇
预防医学   46篇
眼科学   22篇
药学   275篇
中国医学   43篇
肿瘤学   124篇
  2023年   6篇
  2022年   16篇
  2021年   57篇
  2020年   16篇
  2019年   28篇
  2018年   31篇
  2017年   29篇
  2016年   45篇
  2015年   70篇
  2014年   79篇
  2013年   96篇
  2012年   127篇
  2011年   116篇
  2010年   73篇
  2009年   69篇
  2008年   94篇
  2007年   130篇
  2006年   95篇
  2005年   98篇
  2004年   62篇
  2003年   68篇
  2002年   47篇
  2001年   28篇
  2000年   17篇
  1999年   21篇
  1998年   23篇
  1997年   25篇
  1996年   23篇
  1995年   11篇
  1994年   26篇
  1993年   16篇
  1992年   9篇
  1991年   7篇
  1990年   7篇
  1989年   20篇
  1988年   6篇
  1987年   11篇
  1986年   16篇
  1985年   13篇
  1984年   8篇
  1983年   8篇
  1982年   7篇
  1981年   9篇
  1980年   7篇
  1979年   1篇
  1978年   1篇
  1977年   6篇
  1975年   3篇
  1973年   1篇
排序方式: 共有1782条查询结果,搜索用时 15 毫秒
1.
While decreasing trend in gender differences in alcohol use disorders was reported in Western countries, the change in Asian countries is unknown. This study aims to explore the shifts in gender difference in alcohol abuse (AA) and dependence (AD) in Korea. We compared the data from two nation-wide community surveys to evaluate gender differences in lifetime AA and AD by Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). Face-to-face interviews using the Composite International Diagnostic Interview (CIDI) were applied to all subjects in 2001 (n=6,220) and 2011 (n=6,022). Male-to-female ratio of odds was decreased from 6.41 (95% CI, 4.81-8.54) to 4.37 (95% CI, 3.35-5.71) for AA and from 3.75 (95% CI, 2.96-4.75) to 2.40 (95% CI, 1.80-3.19) for AD. Among those aged 18-29, gender gap even became statistically insignificant for AA (OR, 1.59; 95% CI, 0.97-2.63) and AD (OR, 1.18; 95% CI, 0.80-2.41) in 2011. Men generally showed decreased odds for AD (0.55; 95% CI, 0.45-0.67) and women aged 30-39 showed increased odds for AA (2.13; 95% CI 1.18-3.84) in 2011 compared to 2001. Decreased AD in men and increased AA in women seem to contribute to the decrease of gender gap. Increased risk for AA in young women suggests needs for interventions.  相似文献   
2.
3.
4.
5.
OBJECTIVE: To evaluate the pattern of contrast enhancement with Levovist on coded harmonic angiographic ultrasonography of hepatic hemangiomas. METHODS: Twenty hemangiomas were evaluated with coded harmonic angiographic ultrasonography and a microbubble contrast agent. Verification of the diagnosis of a hemangioma was made by means of dynamic computed tomography (n = 8), dynamic magnetic resonance imaging (n = 1), radionuclide scanning (n = 6), or follow-up ultrasonography (n = 5). Ultrasonographic images were obtained before contrast agent administration and with a bolus injection of 2.5 g of a microbubble contrast agent (300 mg/mL Levovist; Schering AG, Berlin, Germany) every 10 to 15 seconds for 5 minutes. The contrast enhancement patterns of the 20 hemangiomas were assessed. RESULTS: The tumor diameters as measured on ultrasonography were 7 to 97 mm (mean, 26.7 mm). Of the 20 hemangiomas, peripheral globular enhancement with progressive centripetal fill-in was shown in 15 (75%), rimlike enhancement with progressive centripetal fill-in was shown in 2 (10%), and homogeneous enhancement was shown in 1 (5%). In the remaining 2 lesions (10%), the enhancement patterns could not be seen, because they were not found on coded harmonic angiographic ultrasonography. CONCLUSIONS: Coded harmonic angiographic ultrasonography with a microbubble contrast agent can depict the typical enhancement pattern in most hepatic hemangiomas.  相似文献   
6.
7.
Two triterpenes 1 and 2 with antiviral activity againstHerpes simplex virus type 1in vitro were isolated fromPrunella vulgaris. Each compound caused a significant reduction in viral cytopathic effect whenvero cells were exposed to them for 72 hours after viral challenge. They were identified asbetulinic acid(1) and 2α, 3α-dihydroxyurs-12-en-28-oic acid(2) on the basis of their spectroscopic properties. The antiviral activity of them was estimated as EC50=30 μg/ml(1) and 8 μg/ml(2), respectively by plaque reduction assay.  相似文献   
8.
BACKGROUND: Practitioners are being encouraged to base their clinical practice on research evidence. In order to do this, they must be aware of and use the sources of evidence. METHODS: A questionnaire survey was undertaken to establish GPs' awareness of research evidence in their clinical practice and, in fundholding practices, its influence on purchasing plans. Questionnaires were sent to 360 lead fundholders in North Thames Region and 440 of a random sample of the remaining general practitioners in the region for comparison. RESULTS: Questionnaires were returned by 62% of lead fundholders and 63% of GPs in the random sample. There was limited use of the electronic sources of clinical effectiveness. There was greater reported awareness of published sources of research evidence and fundholding GPs were significantly more likely to have referred to publications summarizing research evidence. CONCLUSIONS: GPs seem to make more use of published clinical effectiveness sources than the electronic databases. Consequently, they need educational and technical support if they are to make full use of the available sources of research evidence available in other media.   相似文献   
9.
10.

Objective

The aim of this study was to elucidate the clinicopathological significance and prognostic role of loss of claudin-1 in colorectal cancer (CRC).

Methods

The correlations between claudin-1 expression and clinicopathological characteristics, including survival rates, were assessed using immunohistochemistry on 260 archival, paraffin-embedded CRC tissues. In addition, the correlations between cludin-1 and nuclear factor-kappa B (NF-κB), epithelial-mesenchymal transition markers and tumor-infiltrating lymphocytes were investigated.

Results

Claudin-1 expression was markedly lost in 42.7% of the 260 CRCs analyzed. Loss of claudin-1 expression significantly correlated with larger tumor size, vascular invasion, higher pT stage, and high metastatic lymph node ratio. In addition, loss of claudin-1 expression significantly correlated with NF-κB activation (P?<?0.001), high SNAI (P?<?0.001), and low E-cadherin (P?<?0.001) expressions. Patients with high immunoscores showed significantly lower rates of claudin-1 expression loss (P?=?0.020). In detail, loss of claudin-1 expression were frequently found in CRCs low CD3- and CD8-positive lymphocytes. There were significant correlations between claudin-1 expression loss and poor overall and recurrence-free survivals (P?<?0.001 and P?<?0.001, respectively).

Conclusion

Taken together, our results suggest that the loss of claudin-1 expression significantly correlates with aggressive tumor behaviors, high SNAI expression, lower immunoscore, and poor prognoses.  相似文献   
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