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   6177篇
  免费   438篇
  国内免费   20篇
耳鼻咽喉   107篇
儿科学   179篇
妇产科学   121篇
基础医学   897篇
口腔科学   438篇
临床医学   447篇
内科学   1262篇
皮肤病学   145篇
神经病学   445篇
特种医学   133篇
外科学   871篇
综合类   21篇
一般理论   2篇
预防医学   631篇
眼科学   206篇
药学   406篇
中国医学   52篇
肿瘤学   272篇
  2023年   36篇
  2022年   66篇
  2021年   186篇
  2020年   125篇
  2019年   172篇
  2018年   215篇
  2017年   156篇
  2016年   169篇
  2015年   197篇
  2014年   268篇
  2013年   315篇
  2012年   484篇
  2011年   458篇
  2010年   274篇
  2009年   192篇
  2008年   339篇
  2007年   324篇
  2006年   310篇
  2005年   289篇
  2004年   280篇
  2003年   272篇
  2002年   183篇
  2001年   137篇
  2000年   139篇
  1999年   129篇
  1998年   35篇
  1997年   24篇
  1996年   29篇
  1995年   33篇
  1994年   27篇
  1993年   26篇
  1992年   77篇
  1991年   67篇
  1990年   69篇
  1989年   47篇
  1988年   56篇
  1987年   54篇
  1986年   49篇
  1985年   49篇
  1984年   29篇
  1983年   20篇
  1981年   14篇
  1979年   23篇
  1975年   15篇
  1974年   14篇
  1973年   16篇
  1972年   16篇
  1970年   13篇
  1969年   15篇
  1968年   12篇
排序方式: 共有6635条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
BACKGROUND: The role of local excision for pT2 distal rectal cancer has been challenged because of the observation of high rates of lymph node metastases and local failure. However, neoadjuvant chemoradiation therapy (CRT) has led to increased local disease control and significant tumor downstaging, possibly decreasing rates of lymph node metastases. In this setting, a possible role for local excision of ypT2 has been suggested. METHODS: A total of 401 patients with distal rectal cancer underwent neoadjuvant CRT. Tumor response assessment was performed after at least 8 weeks from CRT completion. One hundred and twelve patients with complete clinical response were not immediately operated on and were excluded from the study, and 289 patients with incomplete clinical response were managed by radical surgery. Patients with final pathological stage ypT2 were analyzed to determine the risk of unfavorable pathological features that could represent unacceptable risk for local failure after local excision. RESULTS: Eighty-eight (30%) patients had ypT2 rectal cancer. Final ypT status was not associated with pretreatment radiological staging (p = 0.62). ypT status was significantly associated with the risk of lymph node metastases, risk of perineural and vascular invasion, and recurrence (p = 0.001). Lymph node metastases were present in 19% of patients with ypT2 rectal cancer. The risk of lymph node metastases in ypT2 was associated with the presence of perineural invasion (47% vs 4%; p = <0.001), vascular invasion (59% vs 6%; p < 0.001), and decreased mean interval CRT surgery (12 vs 18 weeks; p < 0.001), but not with mean tumor size (3.2 vs 3.1 cm; p = 0.8). Disease-free and overall survival rates were significantly better for patients with ypT2N0 (p = 0.02 and 0.006, respectively). Fifty-five (63%) patients with ypT2 had at least one unfavorable pathological feature for local excision (lymph node metastases, vascular or perineural invasion, mucinous type or tumor size >3 cm). CONCLUSION: Lymph node metastases were present in 19% of patients with ypT2 and were significantly associated with poor overall and disease-free survival rates. The risk of lymph node metastases could not be predicted by radiological staging or tumor size. Radical surgery should be considered the standard treatment option for ypT2 rectal cancer after CRT.  相似文献   
7.
Several studies have reported that the heart is severely affected by chronic malnutrition. However, the influence of these alterations on cardiac function remains unclear. The aim of this study was to evaluate the effects of subacute starvation on the heart chronotropic response to a beta-adrenergic agonist (isoproterenol). Twelve rats were fed rat chow ad libitum or a 50%-restricted diet for 17 days. The rats were killed, the right atrium was isolated and incubated, and in vitro spontaneous cardiac contractions and frequency were registered. Cumulative doses of isoproterenol were added to the solution until maximal cardiac frequency was achieved. A deficit of 25% in the weight gain was observed in study rats compared with controls (92.6 +/- 10.2 vs. 113.8 +/- 19.2 g, p less than 0.05). Mean daily food intake was 4.8 +/- 0.1 and 9.8 +/- 0.5 g/day for semistarved and control rats, respectively. The in vitro cardiac frequency of the semistarved rats was similar to that of controls (290 +/- 15 and 305 +/- 23 beats/min, respectively, NS). However, when isoproterenol was added to the solution, maximal cardiac frequency of the semistarved rats (435 +/- 51 beats/min) was lower than that of control rats (508 +/- 34 beats/min, p less than 0.005). These findings suggest that subacute starvation may alter the cardiac response to beta-adrenergic agonists.  相似文献   
8.
9.
The objective of this study was to validate the Spanish version of the Othmer and DeSouza Screening Test for Somatization Disorder. We have designed a validity study using the Standardized Polyvalent Psychiatric Interview, an instrument specifically designed to diagnose psychiatric morbidity in medical settings as the ‘golden rule’. The control group displayed ‘functional’ and ‘presenting’ somatization. The Othmer and DeSouza Screening Test, with a threshold of three symptoms, shows 88% sensitivity, 78% specificity and a misclassification rate of 17%. It is concluded that Othmer and DeSouza's screening test, with a threshold of three symptoms, is a useful tool for the diagnosis of somatization disorder in medical and primary care settings in Spain. Discrepancies with US findings are discussed on a cross-cultural basis.  相似文献   
10.
BACKGROUND/PURPOSE: The polysaccharide-rich composition of Aloe vera extracts (Aloe barbadensis Miller), often used in cosmetic formulations, may impart moisturizing properties to the product. The aim of this study was to evaluate the effect of cosmetic formulations containing different concentrations of freeze-dried Aloe vera extract on skin hydration, after a single and a 1- and 2-week period of application, by using skin bioengineering techniques. METHODS: Stable formulations containing 5% (w/w) of a trilaureth-4 phosphate-based blend were supplemented with 0.10%, 0.25% or 0.50% (w/w) of freeze-dried Aloe vera extract and applied to the volar forearm of 20 female subjects. Skin conditions in terms of the water content of the stratum corneum and of transepidermal water loss (TEWL) (Corneometer CM 825 and Tewameter TM 210) were analysed before and after a single and 1- and 2-week period of daily application. RESULTS: After a single application, only formulations supplemented with 0.25% and 0.50% (w/w) of Aloe vera extract increased the water content of the stratum corneum, while after the 2-week period application, all formulations containing the extract (0.10%, 0.25% and 0.50%) had the same effect, in both cases as compared with the vehicle. TEWL was not modified after a single and after 1- and 2-week period of application, when compared with the vehicle. CONCLUSION: Our results show that freeze-dried Aloe vera extract is a natural effective ingredient for improving skin hydration, possibly through a humectant mechanism. Consequently, it may be used in moisturizing cosmetic formulations and also as a complement in the treatment of dry skin.  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