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   917篇
  免费   54篇
  国内免费   27篇
耳鼻咽喉   2篇
儿科学   22篇
妇产科学   23篇
基础医学   61篇
口腔科学   23篇
临床医学   112篇
内科学   187篇
皮肤病学   48篇
神经病学   46篇
特种医学   19篇
外科学   106篇
综合类   73篇
一般理论   3篇
预防医学   91篇
眼科学   4篇
药学   112篇
  1篇
中国医学   43篇
肿瘤学   22篇
  2019年   6篇
  2015年   13篇
  2014年   17篇
  2013年   30篇
  2012年   24篇
  2011年   20篇
  2010年   29篇
  2009年   33篇
  2008年   29篇
  2007年   14篇
  2006年   16篇
  2005年   30篇
  2004年   10篇
  2003年   32篇
  2002年   9篇
  2001年   10篇
  2000年   10篇
  1999年   9篇
  1998年   12篇
  1997年   21篇
  1996年   34篇
  1995年   16篇
  1994年   13篇
  1993年   25篇
  1992年   14篇
  1991年   23篇
  1990年   15篇
  1989年   15篇
  1988年   15篇
  1987年   17篇
  1986年   7篇
  1985年   10篇
  1984年   8篇
  1983年   13篇
  1982年   7篇
  1981年   14篇
  1980年   10篇
  1979年   14篇
  1978年   9篇
  1971年   13篇
  1970年   6篇
  1963年   13篇
  1959年   22篇
  1958年   39篇
  1957年   35篇
  1956年   40篇
  1955年   26篇
  1954年   26篇
  1949年   28篇
  1948年   21篇
排序方式: 共有998条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
Mycosis fungoides (MF) is the most common cutaneous T-cell lymphoma. We report a case in which identical T-cell clones were identified in both patch and tumour stage lesions and in which the tumorous deposits, containing CD30-positive cells, repressed spontaneously. We discuss the differential diagnosis of the tumorous lesions and the spectrum of GD30-positive proliferative T-cell disorders.  相似文献   
6.
A significant minority of medical and dental students fail their undergraduate courses. Early warning systems (EWSs) have been developed in some areas of higher education to predict 'at-risk' students at an early remedial stage. An attempt is made to develop an EWS to predict failure in the bacteriology component of the Batchelor of Dental Surgery course at Manchester Dental School. A system based on class tests and previous end-of-year performance is derived which is used to predict those students likely to fail or fall in the bottom 20-25% in their finals examination. The predictors are combined by a simple equal weights method, which is found to have the same predictive power as using multiple regression. Failure was correctly predicted in 60% of cases, at the expense of 71% false alarms. The high number of false alarms reflects the low failure rate rather than the lack of predictive information. The need for effective cross-validation of EWSs is discussed; many previous studies have not been tested on independent data.  相似文献   
7.
The aim of this study was to determine if the Crithidia luciliae assay for auto-antibodies to double-stranded DNA, often positive in systemic lupus erythematosus, is always negative in auto-immune chronic active hepatitis (CAH) as has recently been suggested. Twenty-five patients were identified as having auto-immune CAH. Mean duration of follow-up was 10.5 years. Antinuclear antibodies were detected in 92%, smooth muscle antibodies in 76% and antimitochondrial antibodies in 16%. Antibodies to double-stranded DNA were detected by the Crithidia assay in four patients (16%). Two of these patients had positive tests on only one occasion and no features of systemic lupus erythematosus. In the other two the assay was persistently positive. During follow-up both developed arthritis and serositis but the liver lesion remained the dominant clinical feature. It was concluded that there is significant serological overlap between auto-immune CAH and systemic lupus erythematosus making the Crithidia assay unreliable in distinguishing between them.  相似文献   
8.
9.
The most common cause of death in patients with colorectal cancer is metastatic liver disease. In order to identify patients at a high risk of developing hepatic secondaries from colorectal cancers, DNA content was measured in metastasizing colorectal primaries (Group I, n= 32) as well as in their subsequently resected liver secondaries and in sections of non-metastasizing colorectal cancers (Group II, n= 25). A modified interpretation system involving both a DNA index and percentage of cycling cells (those in S and G2 + M phases) was developed. DNA content was measured in paraffin-embedded sections by flow cytometry using internal controls (human peripheral blood mononuclear cells) and non-malignant tissue controls (19 patients with diverticular disease). In Group I there were significantly more tumours with both abnormal ploidy (aneuploid or abnormal tetraploid peak) and > 15% cycling cells compared with Group II (Chi-squared; P= 0.034). The combination of abnormal ploidy and > 15% cycling cells was superior to Dukes’ classification for identifying metastasizing tumours (Logistic Regression; P= 0.047). However, it was not possible to discriminate between the two groups using either DNA ploidy or the percentage of cycling cells alone. The metastasizing colorectal cancers exhibited similar DNA ploidy characteristics and had a similar percentage of cycling cells compared with their liver metastases. These results suggest that tumour DNA ploidy plus the percentage of cycling cells may predict the development of liver metastases and thus survival in patients with colorectal cancer.  相似文献   
10.
Prior research indicates that alcohol-related outcome expectancies represent important etiological factors in the understanding of alcohol use/abuse. Although current multidimensional measures assess several substantively different domains of alcohol-related outcome expectancies, there is growing evidence that they may not possess adequate levels of discriminant validity. Therefore, the present study sought to examine whether reliable between-person differences exist in the ability to differentiate among alcohol expectancy domains. The focus of the study was on three sets of intrapersonal characteristics: cognitive resources, cognitive constraints, and alcohol-related experience. Data were collected via household interviews with a random sample of 1125 adults. Multiple regression analysis revealed that higher levels of cognitive resources were associated with increasing levels of differentiation among alcohol expectancy domains. Results are discussed in terms of implications for the development of new or revised multidimensional alcohol expectancy questionnaires. Directions for future research are also discussed.  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