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   2032篇
  免费   172篇
  国内免费   61篇
耳鼻咽喉   5篇
儿科学   98篇
妇产科学   30篇
基础医学   287篇
口腔科学   60篇
临床医学   303篇
内科学   451篇
皮肤病学   35篇
神经病学   110篇
特种医学   259篇
外科学   147篇
综合类   77篇
一般理论   3篇
预防医学   136篇
眼科学   52篇
药学   119篇
中国医学   2篇
肿瘤学   91篇
  2023年   7篇
  2022年   14篇
  2021年   34篇
  2020年   20篇
  2019年   21篇
  2018年   43篇
  2017年   28篇
  2016年   27篇
  2015年   49篇
  2014年   46篇
  2013年   80篇
  2012年   75篇
  2011年   92篇
  2010年   53篇
  2009年   35篇
  2008年   57篇
  2007年   117篇
  2006年   69篇
  2005年   78篇
  2004年   85篇
  2003年   67篇
  2002年   55篇
  2001年   54篇
  2000年   51篇
  1999年   45篇
  1998年   63篇
  1997年   48篇
  1996年   78篇
  1995年   62篇
  1994年   54篇
  1993年   67篇
  1992年   24篇
  1991年   32篇
  1990年   49篇
  1989年   51篇
  1988年   53篇
  1987年   64篇
  1986年   48篇
  1985年   45篇
  1984年   30篇
  1983年   18篇
  1982年   17篇
  1981年   27篇
  1980年   25篇
  1979年   12篇
  1978年   13篇
  1977年   19篇
  1976年   11篇
  1975年   11篇
  1971年   6篇
排序方式: 共有2265条查询结果,搜索用时 156 毫秒
11.
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   
12.
13.
14.
Neck manipulation may uncommonly be associated with serious and even fatal vascular complications. Although well recognised, the nature of the vascular injury has only rarely been directly established by pathological examination. The case is reported of a 43-year-old man who died following neck manipulation, and in whom multiple dissecting aneurysms within both vertebral arteries were demonstrated radiologically and found at necropsy. Bilateral dissecting aneurysms were found both at the level of atlanto-axial articulation and close to the origins of the vertebral arteries. No predisposition was found, other than early atheroma consistent with the patient's age.  相似文献   
15.
16.
17.
18.
19.
By the use of surface plasmon resonance spectroscopy, immunoglobulin G (IgG) subclass and IgM antibodies against three schistosome-derived carbohydrate structures, FLDN (Fucalpha1-3GalNAcbeta1-4GlcNAcbeta1-3Galalpha1), LDN-DF [GalNAcbeta1-4(Fucalpha1-2Fucalpha1-3)GlcNAcbeta1], and LDNF [GalNAcbeta1-4(Fucalpha1-3)GlcNAcbeta1-3Galalpha1], were measured in 184 previously unexposed Kenyan immigrants who moved into the Masongaleni area, where Schistosoma mansoni is endemic. They were sampled within their first year of exposure and again 2 years later. A cohort selected out of the original residents of the area, who had been exposed for many years, served as controls. Associations with responses to S. mansoni worm, egg (SEA), and cercarial (CERC) antigens were examined. In addition, we measured responses to keyhole limpet hemocyanin, a glycoprotein which carries glycan epitopes that are also expressed by schistosomes. Specific IgG1 responses were most pronounced against FLDN and LDN-DF and strongly associated with those previously measured to SEA and CERC. Similarly to previously published age profiles of IgG1 and IgG2 responses to SEA, levels of IgG1 against LDN-DF decreased with age. In contrast, specific IgM responses against the three schistosome-derived carbohydrate structures were most marked against LDNF. Our results indicate that, of the three glycan structures tested, the acute response against schistosome glycoconjugate antigens in young children is mainly directed against the LDN-DF epitope. The response to LDN-DF in older individuals and the responses to the two other epitopes were similar in the two cohorts, suggesting that these antigens are recognized in the early stages of infection and that the immune response persists. The biological significance of these observations needs further elucidation.  相似文献   
20.
The present study was undertaken to assess the temporal association between the profiles of serum concentrations of oestradiol-17beta, progesterone, chorionic gonadotrophin (CG) and relaxin in pregnancies established naturally, and after embryo transfer, as well as in failed pregnancies in rhesus monkeys. In naturally mated cycles (group 1) a conception rate of 75% was obtained. In group 1, the mean day of CG detection in serum was 11.5 +/- 1.9 day post-ovulation, and for relaxin, 9.0 +/- 2.5 day post-ovulation. In group 2, embryo transfer to synchronous, non-mated surrogate recipients was performed; seven embryo transfer cycles yielded three pregnancies which were allowed to continue to term and normal infants were delivered. In embryo transfer cycles the mean day of CG detection was 14.8 +/- 1.8 day post- ovulation, and for relaxin, 11.4 +/- 2.6 day post-ovulation. A delay of about 3 days was observed in the appearance in circulation of CG (P < 0.05) and also of relaxin (P < 0.05) between natural mated and embryo transfer conception cycles. Significant differences (P < 0.05 for progesterone and P < 0.03 for oestradiol) were obtained for the areas under the curves for progesterone and oestradiol between days 12 and 16 in conception cycles compared with failed pregnancies. These data provide the first observation of the normal hormonal signals associated with maternal recognition of transferred embryos during the peri- implantation period, and suggest that the use of such an experimental primate embryo transfer model may help to elucidate components of maternal and embryonic signal-response mechanisms during embryo implantation.   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