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   1607072篇
  免费   111789篇
  国内免费   5100篇
耳鼻咽喉   23962篇
儿科学   46676篇
妇产科学   46099篇
基础医学   225601篇
口腔科学   48447篇
临床医学   135746篇
内科学   316168篇
皮肤病学   36207篇
神经病学   126113篇
特种医学   63561篇
外国民族医学   508篇
外科学   250191篇
综合类   38188篇
现状与发展   6篇
一般理论   501篇
预防医学   105384篇
眼科学   39080篇
药学   122084篇
  6篇
中国医学   4648篇
肿瘤学   94785篇
  2018年   15431篇
  2016年   13536篇
  2015年   15442篇
  2014年   21628篇
  2013年   31682篇
  2012年   41767篇
  2011年   43881篇
  2010年   26234篇
  2009年   25386篇
  2008年   41453篇
  2007年   45152篇
  2006年   45361篇
  2005年   43523篇
  2004年   42096篇
  2003年   40631篇
  2002年   39868篇
  2001年   80378篇
  2000年   82459篇
  1999年   69659篇
  1998年   18289篇
  1997年   16449篇
  1996年   15598篇
  1995年   14660篇
  1994年   13632篇
  1993年   12647篇
  1992年   53083篇
  1991年   50598篇
  1990年   49587篇
  1989年   48381篇
  1988年   44960篇
  1987年   44101篇
  1986年   41924篇
  1985年   39833篇
  1984年   29439篇
  1983年   24861篇
  1982年   14606篇
  1981年   13138篇
  1979年   27838篇
  1978年   19506篇
  1977年   17021篇
  1976年   15103篇
  1975年   17270篇
  1974年   20373篇
  1973年   19777篇
  1972年   18997篇
  1971年   17862篇
  1970年   16819篇
  1969年   16256篇
  1968年   15160篇
  1967年   13481篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
This study assessed the amount of vascular endothelial growth factor (VEGF) expression and related the findings to new bone formation in the posterior glenoid fossa during stepwise mandibular advancement. A total of 250 female Sprague-Dawley rats, 35 days old, were randomly divided into 10 groups, each including 5 control and 20 experimental rats. Within each group, 10 experimental rats were fitted with functional appliances with a 1-step advancement of 3.5 mm. Another 10 were fitted with stepwise appliances with an initial advancement of 2 mm and a subsequent increase to 3.5 mm on day 30. The rats in the experimental groups were killed on days 3, 7, 14, 21, 30, 33, 37, 44, 51, and 60, respectively. The matched controls were killed on the same time points. Sections (7 microm) were cut through the glenoid fossa sagittally and stained with anti-VEGF antibody. VEGF expression in the posterior glenoid fossa was evaluated with a computer-assisted image-analyzing system. Both VEGF expression and new bone formation were greater in the experimental rats than in the controls. During stepwise advancement, initial VEGF expression was less than that of 1-step advancement, but the second advancement elicited another peak on day 44. New bone formation was also less than that of 1-step advancement during early stages of stepwise advancement but then began to increase from day 37 onward. The maximum increase was observed on day 60. Stepwise advancement of the mandible delivers mechanical stimuli that produce a series of tissue responses that lead to increased vascularization and bone formation.  相似文献   
992.
993.
We report a 24-year-old woman with an intramedullary conus ependymoma associated with holocord syringohydromyelia and syringobulbia. The tumor was removed and surgery for decompression of the syringohydromyelia was not considered at the first operation. In the follow-up examinations, MRI showed significant and steady improvement of syringohydromyelia. Symptoms associated with syringohydromyelia also disappeared. The cause of syringohydromyelia accompanying intradural spinal cord tumors appears to be either direct blockade of the central canal or secondary interruption of the central canal flow by compression of the perimedullary cerebrospinal fluid flow. As removal of the mass often corrects both these likely causes of the syringohydromyelia, no additional treatment for the drainage of the hydromyelia cavity syrinx is usually necessary.  相似文献   
994.
BACKGROUND: Solid organ transplant recipients may develop numerous or life-threatening skin cancers. In addition to aggressive standard treatment of skin cancer, reduction of immunosuppression has been considered an adjuvant therapeutic strategy, albeit without direct proof of efficacy. OBJECTIVE: To review the rationale for and evidence supporting the efficacy of reduction of immunosuppression for severe skin cancer in transplant recipients. METHODS: Review of the literature regarding direct and indirect evidence on reduction of immunosuppression for transplant-associated skin cancer. RESULTS: Although there are no randomized controlled trials of reduction of immunosuppression as a therapeutic intervention for transplant patients with skin cancer, multiple lines of evidence suggest that this strategy may be an effective adjuvant therapy. A randomized trial has demonstrated a lower incidence of skin cancer in transplant recipients after reduction of immunosuppression, albeit in a cohort not previously affected by skin cancer. Case series of reduction or cessation of immunosuppression demonstrate a lower incidence of skin cancer or improved outcomes of preexisting skin cancer. Lower overall immunosuppression is associated with a lower incidence of skin cancer. Multiple cancers affecting the skin have been shown to regress with reduction of immunosuppression. CONCLUSIONS: Reduction of immunosuppression may be an effective adjuvant therapeutic strategy when confronting severe transplant-associated skin cancer. The risks of reduction of immunosuppression must be better defined, and randomized trials of this strategy are necessary.  相似文献   
995.
996.
997.
998.
Dissection of the thoracic aorta is a life-threatening event requiring imaging studies to define the level of the tear and the intinmal flap. The “gold standard” has been angiography. This method may fail to demonstrate the dissection, however, due to overlap of the true and false lumens or a very thin flap that is imaged en face rather than tangentially. Computed tomography has a diagnostic accuracy of 95%, but can fail to image the dissection due to technical factors or a thrombosed false hunen. Magnetic resonance imaging requires a hemodynamically stable and cooperative patient. A diagnostic algorithm is proposed for diagnosis of aortic dissection based on renal function and the surgeon's imaging modality preference.  相似文献   
999.
1000.
Five years after treatment in a controlled trial, in which all had received self-exposure homework, a group of 40 agoraphobic outpatients retained marked improvement in agoraphobia, mood, and free-floating anxiety. Frequency of spontaneous panics decreased as much in those who had placebo and self-exposure as in those who received imipramine and self-exposure. Few patients, however, were completely well at 5 years and over half had received further treatment for agoraphobia during the follow-up. Patients who were still highly phobic at the end of the clinical trial were more often prescribed psychotropic medication during follow-up and remained phobic at 5 years. Phobic improvement had generalized more in those patients with very low than in those with moderate pretreatment Hamilton depression scores. Frequency of initial spontaneous panics did not predict outcome. Improvement in agoraphobia was associated with improved marital adjustment. Those who began with the best marital, work, and social adjustment were more improved in their phobias 5 years later.  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