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   1474篇
  免费   90篇
  国内免费   65篇
耳鼻咽喉   12篇
儿科学   58篇
妇产科学   22篇
基础医学   158篇
口腔科学   24篇
临床医学   191篇
内科学   412篇
皮肤病学   23篇
神经病学   115篇
特种医学   245篇
外科学   97篇
综合类   30篇
一般理论   2篇
预防医学   82篇
眼科学   8篇
药学   97篇
  1篇
中国医学   2篇
肿瘤学   50篇
  2023年   6篇
  2022年   3篇
  2021年   19篇
  2020年   5篇
  2019年   14篇
  2018年   22篇
  2017年   13篇
  2016年   17篇
  2015年   42篇
  2014年   39篇
  2013年   52篇
  2012年   74篇
  2011年   62篇
  2010年   53篇
  2009年   40篇
  2008年   53篇
  2007年   83篇
  2006年   41篇
  2005年   45篇
  2004年   37篇
  2003年   35篇
  2002年   40篇
  2001年   27篇
  2000年   28篇
  1999年   43篇
  1998年   59篇
  1997年   41篇
  1996年   64篇
  1995年   55篇
  1994年   47篇
  1993年   52篇
  1992年   19篇
  1991年   23篇
  1990年   29篇
  1989年   34篇
  1988年   44篇
  1987年   41篇
  1986年   31篇
  1985年   38篇
  1984年   19篇
  1983年   12篇
  1982年   17篇
  1981年   23篇
  1980年   21篇
  1979年   7篇
  1978年   10篇
  1977年   17篇
  1976年   8篇
  1975年   10篇
  1964年   2篇
排序方式: 共有1629条查询结果,搜索用时 38 毫秒
1.
2.
3.
Results are presented of a Phase III international multicentre trial to study the effect of a new low-dose oral contraceptive (OC) containing 20 micrograms ethinylestradiol and 150 micrograms desogestrel (Mercilon) regarding efficacy, cycle control, blood pressure, and acceptability. Altogether 1,684 women from 12 European countries were included in the study. Four pregnancies occurred, 3 of them patient failures, one tablet failure. The overall Pearl Index was 0.20. The frequency of irregular bleeding was comparable to that recorded with other commonly used low-dose OCs. No serious side effects occurred. The incidence of the most frequently reported subjective side effects--headache, nausea and breast tension--was already low after the first cycle of treatment and decreased to below pretreatment levels with continued use. There was a small increase in mean body weight, which was confined essentially to young women. The preparation did not affect the mean systolic or diastolic blood pressure. This new preparation has thus proved to be an effective, safe and well-accepted ultra low-dose oral contraceptive.  相似文献   
4.
5.
6.
Inversion recovery (IR), commonly considered a pulse sequence capable of producing T1-weighted images with excellent display of normal anatomy, is versatile: The null point and peak time provide a useful, succinct summary of the properties of IR and its capacity for producing both T1- and T2-weighted images. Shortening of the inversion time (TI) and creation of a short-TI inversion-recovery (STIR) pulse sequence increases sensitivity to malignancy and other abnormalities by making the effects of prolonged T1 and T2 on signal intensity additive and by nulling the signal from fat. The authors examined over 300 patients with various malignancies and compared STIR images with T1- and T2-weighted images obtained at 0.5 T. In 43 cases, signal-difference-to-noise ratios (SD/Ns) were calculated between tumor, fat, and muscle. In general, STIR images demonstrated tumor as a conspicuously high-intensity area in a background of muted, discernible anatomic detail. The good contrast achieved with STIR sequences between tumor and fat (SD/N = 18.1) and tumor and muscle (SD/N = 12.9) consolidated into a single image the information contained separately on T1- and T2-weighted images, which facilitates efficient detection and localization of malignancy.  相似文献   
7.
Goei  R; Baeten  C; Arends  JW 《Radiology》1988,168(2):303-306
Sixteen cases of histopathologically proved solitary rectal ulcer syndrome were encountered. Fifteen patients underwent barium enema study; in nine cases the findings--including rectal stricture, granularity of the mucosa, and thickened rectal folds-were nonspecific. In six cases the study was normal. All patients had a long history of defecation disorders, and defecography was performed in all. In seven cases, intussusception of the rectal wall was seen; in another case the intussusception was accompanied by a rectocele. One case showed rectal prolapse. In four cases, failed relaxation of the puborectalis occurred and prevented the passage of the bolus; in another case there was abnormal perineal descent. In two patients studies were normal. In patients with defecation disorders, the possibility of this syndrome should be considered. Defecography is the method of choice for establishing the diagnosis.  相似文献   
8.
9.
10.
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