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   983篇
  免费   77篇
  国内免费   6篇
耳鼻咽喉   7篇
儿科学   43篇
妇产科学   12篇
基础医学   134篇
口腔科学   8篇
临床医学   127篇
内科学   238篇
皮肤病学   1篇
神经病学   131篇
特种医学   23篇
外科学   127篇
综合类   1篇
一般理论   1篇
预防医学   105篇
眼科学   18篇
药学   33篇
肿瘤学   57篇
  2023年   4篇
  2022年   6篇
  2021年   31篇
  2020年   27篇
  2019年   41篇
  2018年   37篇
  2017年   36篇
  2016年   42篇
  2015年   22篇
  2014年   40篇
  2013年   68篇
  2012年   74篇
  2011年   82篇
  2010年   46篇
  2009年   40篇
  2008年   48篇
  2007年   67篇
  2006年   74篇
  2005年   53篇
  2004年   37篇
  2003年   39篇
  2002年   33篇
  2001年   9篇
  2000年   9篇
  1999年   4篇
  1998年   9篇
  1997年   13篇
  1996年   8篇
  1995年   6篇
  1994年   1篇
  1993年   4篇
  1992年   3篇
  1991年   5篇
  1990年   6篇
  1989年   5篇
  1988年   10篇
  1987年   1篇
  1986年   2篇
  1985年   1篇
  1984年   1篇
  1983年   2篇
  1982年   2篇
  1981年   2篇
  1980年   1篇
  1979年   4篇
  1978年   5篇
  1977年   5篇
  1975年   1篇
排序方式: 共有1066条查询结果,搜索用时 31 毫秒
91.
BACKGROUND & AIMS: The colectomy rate in ulcerative colitis (UC) is related to morbidity and to treatment decisions made during disease course. The aims of this study were to determine the colectomy risk in UC in the first decade after diagnosis and to identify factors that may influence the choice of surgical treatment. METHODS: In 1991-1993, 781 UC patients from 9 centers located in 7 countries in northern and southern Europe and in Israel were included in a prospective inception cohort study. After 10 years of follow-up, 617 patients had complete medical records, 73 had died, and 91 had been lost to follow-up. RESULTS: There were no significant differences in age, sex, or disease extent at diagnosis between patients followed for 10 years and those lost to follow-up. The 10-year cumulative risk of colectomy was 8.7%: 10.4% in the northern and 3.9% in the southern European centers (P < .001). Colectomy was more likely in extensive colitis than in proctitis, with an adjusted hazard ratio (HR) of 4.1 (95% CI: 2.0-8.4). Compared with the southern centers, the adjusted HR was 2.7 (95% CI: 1.3-5.6) for The Netherlands and Norway together and 8.2 (95% CI: 3.6-18.6) for Denmark. Age at diagnosis, sex, and smoking status at diagnosis had no statistically significant influence on colectomy rates. CONCLUSIONS: The colectomy rate was found to be lower than that in previous publications, but there was a difference between northern and southern Europe. Colectomy was associated with extensive colitis, but the geographic variations could not be explained.  相似文献   
92.
The purpose of this study was to identify the receptor responsible for endocytosis of denatured collagen from blood. The major site of clearance of this material (at least 0.5 g/day in humans) is a receptor on liver sinusoidal endothelial cells (LSECs). We have now identified an 180-kDa endocytic receptor on LSECs, peptide mass fingerprinting of which revealed it to be the mannose receptor. Challenge of mannose-receptor knockout mice and their cultured LSECs revealed significantly reduced blood clearance and a complete absence of LSEC endocytosis of denatured collagen. Organ analysis of wild-type versus knockout mice after injection of denatured collagen revealed significantly reduced liver uptake in the knockout mice. Clearance/endocytosis of ligands for other receptors in these animals was as that for wild-type mice, and denatured collagen uptake in wild-type mice was not affected by other ligands of the mannose receptor, namely mannose and mannan. Furthermore, unlike that of mannose and mannan, endocytosis of denatured collagen by the mannose receptor is calcium independent. This suggests that the binding site for denatured collagen is distinct from that for mannose/mannan. Mannose receptors on LSECs appear to have less affinity for circulating triple helical type I collagen. CONCLUSION: The mannose receptor is the main candidate for being the endocytic denatured collagen receptor on LSECs.  相似文献   
93.
Purpose To evaluate the feasibility of using contrast-enhanced ultrasound (CEUS) during uterine artery embolization (UAE) in order to define the correct end-point of embolization with complete devascularization of all fibroids. Methods In this prospective study of 10 consecutive women undergoing UAE, CEUS was performed in the angiographic suite during embolization. When the angiographic end-point, defined as the “pruned-tree” appearance of the uterine arteries was reached, CEUS was performed while the angiographic catheters to both uterine arteries were kept in place. The decision whether or not to continue the embolization was based on the findings at CEUS. The results of CEUS were compared with those of contrast-enhanced magnetic resonance imaging (MRI) 1 day as well as 3 months following UAE. Results CEUS was successfully performed in all women. In 4 cases injection of particles was continued based on the findings at CEUS despite angiographically complete embolization. CEUS imaging at completion of UAE correlated well with the findings at MRI. Conclusion The use of CEUS during UAE is feasible and may increase the quality of UAE.  相似文献   
94.

Objective

This article examines reliability and validity aspects of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) paranoid personality disorder (PPD) diagnosis.

Method

Patients with personality disorders (n = 930) from the Norwegian network of psychotherapeutic day hospitals, of which 114 had PPD, were included in the study. Frequency distribution, χ2, correlations, reliability statistics, exploratory, and confirmatory factor analyses were performed.

Results

The distribution of PPD criteria revealed no distinct boundary between patients with and without PPD. Diagnostic category membership was obtained in 37 of 64 theoretically possible ways. The PPD criteria formed a separate factor in a principal component analysis, whereas a confirmatory factor analysis indicated that the DSM-IV PPD construct consists of 2 separate dimensions as follows: suspiciousness and hostility. The reliability of the unitary PPD scale was only 0.70, probably partly due to the apparent 2-dimensionality of the construct. Persistent unwarranted doubts about the loyalty of friends had the highest diagnostic efficiency, whereas unwarranted accusations of infidelity of partner had particularly poor indicator properties.

Conclusions

The reliability and validity of the unitary PPD construct may be questioned. The 2-dimensional PPD model should be further explored.  相似文献   
95.
96.
97.
98.
OBJECTIVES: Cumulative 10-yr relapse rates in ulcerative colitis (UC) of 70% to almost 100% have been reported in regional studies. The aim of this study was to determine the relapse rate in UC in a European population-based cohort 10 yr after diagnosis and to identify factors that may influence the risk of relapse. METHODS: From 1991 to 1993, 771 patients with UC from seven European countries and Israel were prospectively included in a population-based inception cohort and followed for 10 yr. A relapse was defined as an increase in UC-related symptoms leading to changes in medical treatment or surgery. The cumulative relapse rate, time to first relapse, and number of relapses in the follow-up period were recorded and possible causative factors were investigated. RESULTS: The cumulative relapse rate of patients with at least one relapse was 0.67 (95% CI 0.63-0.71). The time to first relapse showed a greater hazard ratio (HR) (1.2, CI 1.0-1.5) for women and for patients with a high level of education (1.4, CI 1.1-1.8). The number of relapses decreased with age, and current smokers had a lower relapse rate (0.8, CI 0.6-0.9) than nonsmokers. The relapse rate in women was 1.2 (CI 1.1-1.3) times higher than in men. An inverse relation was found between the time to the first relapse and the total number of relapses. CONCLUSION: In 67% of patients, there was at least one relapse. Smoking status, level of education, and possibly female gender were found to influence the risk of relapse.  相似文献   
99.
100.
The study's objective was to identify HPA 1a-negative women and to offer them an intervention program aimed to reduce morbidity and mortality of neonatal alloimmune thrombocytopenia (NAIT). HPA 1 typing was performed in 100 448 pregnant women. The HPA 1a-negative women were screened for anti-HPA 1a. In immunized women, delivery was performed by Cesarean section 2 to 4 weeks prior to term, with platelets from HPA 1a-negative donors reserved for immediate transfusion if petechiae were present and/or if platelet count was less than 35 x 10(9)/L. Of the women screened, 2.1% were HPA 1a negative, and anti-HPA 1a was detected in 10.6% of these. One hundred seventy pregnancies were managed according to the intervention program, resulting in 161 HPA 1a-positive children. Of these, 55 had severe thrombocytopenia (< 50 x 10(9)/L), including 2 with intracranial hemorrhage (ICH). One woman with a twin pregnancy missed the follow-up and had one stillborn and one severely thrombocytopenic live child. In 15 previous prospective studies (136 814 women) there were 51 cases of severe NAIT (3 intrauterine deaths and 7 with ICH). Acknowledging the limitation of comparing with historic controls, implementation of our screening and intervention program seemed to reduce the number of cases of severe NAIT-related complications from 10 of 51 to 3 of 57.  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