首页 | 官方网站   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   1074927篇
  免费   71762篇
  国内免费   1366篇
医药卫生   1148055篇
  2019年   7755篇
  2018年   11294篇
  2017年   8910篇
  2016年   10097篇
  2015年   11260篇
  2014年   15273篇
  2013年   22205篇
  2012年   30549篇
  2011年   32299篇
  2010年   18957篇
  2009年   17819篇
  2008年   29953篇
  2007年   32072篇
  2006年   32711篇
  2005年   31036篇
  2004年   29733篇
  2003年   28560篇
  2002年   27533篇
  2001年   60021篇
  2000年   61479篇
  1999年   50929篇
  1998年   12448篇
  1997年   11002篇
  1996年   11016篇
  1995年   10322篇
  1994年   9343篇
  1993年   8858篇
  1992年   37792篇
  1991年   36280篇
  1990年   35746篇
  1989年   34290篇
  1988年   30864篇
  1987年   29988篇
  1986年   28217篇
  1985年   26451篇
  1984年   19188篇
  1983年   16115篇
  1982年   8822篇
  1979年   17030篇
  1978年   11404篇
  1977年   10230篇
  1976年   8837篇
  1975年   10068篇
  1974年   11654篇
  1973年   11276篇
  1972年   10755篇
  1971年   10094篇
  1970年   9253篇
  1969年   8938篇
  1968年   7919篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
We report our experience of eight cases of isolated full thickness burns of the penis. Early excision of burns of the penile shaft and repair with a preputial flap or mesh split skin graft produces excellent results, with a reduction in complications and an early re-establishment of sexual function. Conservative treatment of burns of the glans, on the other hand, is appropriate and results in minimal scarring.  相似文献   
122.
Clinical versus ultrasonographic evaluation of scrotal disorders   总被引:1,自引:0,他引:1  
Clinical and ultrasonographic examinations of scrotal disorders were compared in 166 patients in order to determine their ability to distinguish between those diseases requiring surgery and those requiring clinical follow-up only. Ultrasound examinations were efficient in discriminating between normal and pathological findings. Extra-testicular lesions were readily differentiated from testicular ones. Although both clinical and ultrasonographic examinations had high sensitivity (90%) in detecting testicular cancer, the number of false positive findings was smaller after ultrasound examination. This gave a predictive value of a positive test of 53% after ultrasound examination but only 33% after clinical examination. Ultrasound examination may, therefore, reduce the number of surgical explorations in the scrotum and should be performed in patients with suspected testicular pathology based on history and palpatory findings.  相似文献   
123.
124.
125.
126.
127.
Choristomas, masses of normal tissues in aberrant locations, contain smooth muscle fibers and fibrous tissues. We describe the MR imaging features of two choristomas located in the internal auditory canals and arising from the facial and vestibulocochlear nerves. Both lesions enhanced with contrast material. In one case, enhancement was seen in the geniculate ganglion and greater superficial petrosal nerve. In the other, a medial component enhanced less than the lateral component did.  相似文献   
128.
The ability of three Porphyromonas spp., seven Prevotella spp., seven Fusobacterium spp. and two related Bacteroides spp. (B. levii and B. macacae) to degrade an extensive range of synthetic endo-, amino- and diamino peptidase substrates linked to the fluorescent leaving group 7-amido-4-methylcoumarin (NHMec) was investigated. Many more species than was previously recognized exhibited peptidase activities, albeit at lower levels than those already described for Porphyromonas gingivalis. Detection of chymotrypsin-like activity was dependent on which of three NHMec-linked substrates was used, but all species exhibited degradative activity with at least one of these substrates. Elastase-like activity was detected in all species though not all species reacted with each of the elastase substrates. Glycylprolyl peptidase activity was detected in all of the species tested with the exception of F. mortiferum, F. gonidiaformans, F. naviforme and F. necrophorum. While the detection of peptidase activities does not appear to be useful for the differentiation of species within the genera Bacteroides and Prevotella, its ability to differentiate species of the genus Porphyromonas or Fosobacterium further investigation.  相似文献   
129.
Tissue specimens from the large bowel of 18 patients with long-standing slow transit constipation were investigated to determine the distribution and density of several neuropeptides and amines in the enteric nerve system, and also of endocrine cells in comparison to normal individuals. CGRP (calcitonin gene-related peptide), galanin, glucagon, GRP (gastrin-releasing peptide), metenkephalin, motilin, neuropeptide Y (NPY), PACAP, peptide YY (PYY), serotonin, somatostatin, substance P and VIP were studied by immunohistochemistry. Tissue concentrations of VIP, substance P and galanin were also measured by radioimmunoassay. Significantly increased VIP, SP and galanin contents were found in specimens from the ascending colon. Levels of VIP and galanin were also increased in the transverse colon. Immunohistochemistry revealed only marginal changes with an increased density of PACAP nerve fibres in the smooth muscle and of VIP and PACAP nerves in the myenteric plexus of the transverse colon. In the descending colon substance P and NPY immunoreactivity were also increased in the myenteric plexus while the density of VIP nerve fibres was reduced in the mucosa/submucosa. The frequency of PYY-containing cells and the 5-HT-containing cells in the ascending colon was significantly increased in the constipated patients.  相似文献   
130.
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-23

京公网安备 11010802026262号