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   18721篇
  免费   1493篇
  国内免费   86篇
耳鼻咽喉   227篇
儿科学   521篇
妇产科学   302篇
基础医学   2362篇
口腔科学   260篇
临床医学   2013篇
内科学   4729篇
皮肤病学   234篇
神经病学   1369篇
特种医学   670篇
外科学   2879篇
综合类   265篇
一般理论   10篇
预防医学   1386篇
眼科学   635篇
药学   1121篇
中国医学   50篇
肿瘤学   1267篇
  2023年   91篇
  2022年   133篇
  2021年   297篇
  2020年   188篇
  2019年   359篇
  2018年   366篇
  2017年   299篇
  2016年   311篇
  2015年   332篇
  2014年   509篇
  2013年   762篇
  2012年   1083篇
  2011年   1057篇
  2010年   656篇
  2009年   642篇
  2008年   1092篇
  2007年   1151篇
  2006年   1180篇
  2005年   1115篇
  2004年   1083篇
  2003年   1037篇
  2002年   964篇
  2001年   322篇
  2000年   316篇
  1999年   267篇
  1998年   210篇
  1997年   193篇
  1996年   150篇
  1995年   195篇
  1994年   154篇
  1993年   125篇
  1992年   217篇
  1991年   175篇
  1990年   186篇
  1989年   176篇
  1988年   188篇
  1987年   173篇
  1986年   157篇
  1985年   135篇
  1984年   139篇
  1983年   147篇
  1982年   143篇
  1981年   127篇
  1980年   122篇
  1979年   109篇
  1978年   108篇
  1977年   120篇
  1976年   92篇
  1974年   78篇
  1973年   63篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
Minocycline is an antibiotic now recognized to have antiapoptotic and antiinflammatory properties. Because of these properties, minocycline may be of benefit in reducing neuronal apoptosis from ischemia and subsequent postischemic inflammation if administered soon after a stroke. We now explore the feasibility of using (99m)Tc-annexin V, an in vivo marker of apoptosis, with SPECT to monitor the antiapoptotic effects of minocycline therapy. METHODS: CB6/F1 adult male mice underwent unilateral distal middle cerebral artery occlusion (dMCA) occlusion and were imaged and sacrificed at 1, 3, 7, or 30 d after injury. Animals were given minocycline (or vehicle) 30 min and 12 h after dMCA occlusion and then given 22.5 mg/kg twice daily for up to 7 d. Before imaging, behavioral tests were performed to evaluate the neurologic function. After imaging, brains were collected for histology and assessed for the degree of apoptosis and microglial activation. RESULTS: (99m)Tc-Annexin V uptake in injured hemispheres was significantly decreased 2- to 3-fold by minocycline at all time points. Minocyline reduced infarct size as seen histologically and improved behavioral indices as late as 30 d. Infarct volume as seen histologically correlated with radiolabeled annexin V uptake seen by SPECT. In situ fluorescent microscopy demonstrated that annexin V bound primarily to neurons at 1 and 3 d, with a shift toward microglia by 7 and 30 d. CONCLUSION: We found that minocycline significantly reduces neuronal apoptosis and infarct size and improves neurologic outcome in mice after acute focal cortical ischemia.  相似文献   
34.
BACKGROUND: Ten percent of gastric cancer (GC) cases are familial, with one third resulting from a mutation in the tumor suppressor gene CDH1. Loss of this important structure can result in hereditary diffuse gastric cancer (HDGC), which carries a high mortality if early diagnosis is not made. Despite its clear genetic origin, optimal management of HDGC family members is controversial, as the utility and efficacy of current cancer screening programs for mutation carriers are unproven. METHODS: A 53-year-old Caucasian woman was initially seen for genetic screening because multiple family members had mutations of the CDH1 gene. Her pedigree analysis demonstrated 4 generations of gastric cancer, and 2 of the generations carried the CDH1 germline mutation, consistent with HDGC. At endoscopy, the patient's gastric mucosa was normal and random biopsies were also normal. The patient underwent a laparoscopic total gastrectomy. RESULTS: The gross examination of her stomach appeared normal. On histologic examination, however, the stomach was found to have diffuse (signet ring cell) adenocarcinoma in-situ with 11 microscopic foci of invasive adenocarcinoma limited to the lamina propria. CONCLUSION: Our case is the first reported prophylactic total gastrectomy utilizing a laparoscopic approach, and it highlights the importance of taking a thorough family history and obtaining a pedigree analysis. Endoscopic screening in HDGC cannot rule out diffuse GC, because the stomach and biopsies can be normal despite the presence of adenocarcinoma. Therefore, our case supports the recommendation for prophylactic gastrectomy in HDGC.  相似文献   
35.
Objective  The objective of this study was to describe the perceived health status of the meat industry employees—i.e., working in the slaughtering, cutting, and boning of large animals and poultry—and its relation to their organisational and psychosocial constraints at work. Methods  This postal survey included all 3,000 employees of the meat industry (beef, pork and poultry) in four districts in Brittany, France, whose companies were affiliated with the agricultural branch of the national health insurance fund. The questionnaire asked for social and demographic data and information describing their job and the organisation of their work. The psychosocial factors at work were described according to Karasek’s questionnaire (demand, latitude and social support at work). Perceived health was measured with the Nottingham Health Profile perceived health indicator. Results  This study shows the high prevalence of poor health reported by the workers in this industry. This poor perceived health was worse in women and increased regularly with age. Among the psychosocial factors studied, high quantitative and qualitative demand at work, inadequate resources for good work and to a lesser extent, inadequate prospects for promotion appear especially associated with poor perceived health. Other factors often associated with poor perceived health included young age at the first job and work hours that disrupt sleep rhythms (especially for women). Conclusion  Our results show that this population of workers is especially vulnerable from the point of view of perceived physical and psychological health and is exposed to strong physical, organisational and psychosocial constraints at work. They also demonstrate that poor perceived health is associated with some psychosocial (such as high psychological demand and insufficient resources) and organisational factors at work. These results, in conjunction with those from other disciplines involved in studying this industry, may help the companies to develop preventive activities.  相似文献   
36.
37.
The objective of this study was to evaluate the epidemiology, diagnosis, pathophysiology, and treatment of bone loss related to anorexia nervosa. Earlier onset and longer duration of anorexia nervosa are associated with more severe bone loss. Osteoporosis develops in 38 to 50% of cases. Bone mineral density measurement by dual-energy X-ray absorptiometry is useful for assessing bone mass, and bone marker assays provide information on bone turnover. Bone loss in anorexia nervosa is probably multifactoriel. Estrogen deficiency was long felt to be the major factor. However, in contrast to postmenopausal osteoporosis, bone loss associated with anorexia nervosa is related mainly to inadequate bone formation, with only a slight increase in bone resorption. This suggests a role for nutritional factors, such as disturbances in the growth hormone-somatomedin C axis (GH/IGF-I) related to malnutrition. The best treatment strategy for correcting bone mass in patients with anorexia nervosa is not agreed on. Resumption of menstrual cycles and weight gain seem necessary but not always sufficient. Studies found no benefits with estrogen therapy, but this was usually given as estrogen–progestin contraceptives. No vast studies evaluating hormone replacement therapy have been reported. Bone formation enhancers such as IGF-I seem to provide the best results, most notably when used in combination with estrogens. This suggests that complex treatment strategies combining bone formation enhancers and bone resorption inhibitors may deserve evaluation.  相似文献   
38.
39.
40.
We performed a prospective study to analyze the functional results following elective laparoscopic sigmoidectomy for computed tomography (CT)-proven diagnosis of acute diverticulitis and review the literature. Forty-three of 45 available patients (96%) who had laparoscopic sigmoidectomy for CT-proven acute diverticulitis answered, after a mean time of 40 months, a questionnaire exploring new abdominal symptoms, bowel function, and the patient’s own judgement of the surgical outcome. Surgical technique aimed at removing all the sigmoid by taking down the splenic flexure and do a colorectal anastomosis. Four patients (9%) complained of new abdominal pain. Bowel function was reported as better for 24 patients (56%), unchanged for 16 patients (37%), and worse for 3 (7%). Twenty patients (47%) considered their final result as excellent to good, 17 patients (40%) as satisfying, and 6 patients (13%) as mediocre. Male gender, absence of preoperative history compatible with an irritable bowel syndrome, length of resected sigmoid and residual acute inflammation on histology are statistically predictive of a better postoperative degree of satisfaction. After elective laparoscopic sigmoidectomy for CT-proven diverticulitis, a great majority of patients are very satisfied with their postoperative general comfort.  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