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   230264篇
  免费   18377篇
  国内免费   4351篇
耳鼻咽喉   3724篇
儿科学   4283篇
妇产科学   3660篇
基础医学   18486篇
口腔科学   7553篇
临床医学   20558篇
内科学   21426篇
皮肤病学   2488篇
神经病学   14189篇
特种医学   6174篇
外国民族医学   12篇
外科学   21526篇
综合类   35686篇
现状与发展   9篇
一般理论   24篇
预防医学   30385篇
眼科学   2387篇
药学   21045篇
  364篇
中国医学   29139篇
肿瘤学   9874篇
  2024年   4704篇
  2023年   5797篇
  2022年   8996篇
  2021年   11608篇
  2020年   11300篇
  2019年   12534篇
  2018年   10766篇
  2017年   9373篇
  2016年   8243篇
  2015年   7715篇
  2014年   14792篇
  2013年   15202篇
  2012年   13185篇
  2011年   14034篇
  2010年   11333篇
  2009年   9888篇
  2008年   9192篇
  2007年   9233篇
  2006年   7879篇
  2005年   6668篇
  2004年   5604篇
  2003年   4951篇
  2002年   3817篇
  2001年   3197篇
  2000年   2794篇
  1999年   2284篇
  1998年   1862篇
  1997年   1696篇
  1996年   1361篇
  1995年   1303篇
  1994年   1167篇
  1993年   1037篇
  1992年   955篇
  1991年   873篇
  1990年   767篇
  1989年   748篇
  1988年   679篇
  1987年   619篇
  1986年   566篇
  1985年   1863篇
  1984年   2128篇
  1983年   1337篇
  1982年   1758篇
  1981年   1231篇
  1980年   1044篇
  1979年   932篇
  1978年   775篇
  1977年   579篇
  1976年   712篇
  1975年   484篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Summary.  The expression of adhesion molecules on human spermatozoa of healthy probands was analysed. The localization patterns of adhesion molecules (AM) on the spermatozoal surface were documented by fluorescence microscopy. Spermatozoa were incubated with antibodies against α1 (CD49a), α2 (CD49b), α3 (CD49c), α4 (CD49d), α5 (CD49e), α6 (CD49f) chains of β1 integrins, β1 (CD29), β2 (CD18), αV (CD51), β3 (CD61) and β4 integrin chains, the LFA-3 (Lymphocyte function antigen, CD58) from the immunoglobulin superfamily and the extracellular matrix proteins laminin, fibronectin and collagen IV. For collagen IV, α1 and α2 chains no expression could be noticed. Laminin was detected at the acrosomal membrane, fibronectin and β4 chain mainly at the equatorial membrane. The fibronectin receptors α3, α4 and α5 chains of the β1 integrins were mainly located on acrosomal and equatorial membrane areas. Laminin receptor α6 chain was located postacrosomal and less frequently acrosomal. β2 chain and vitronectin receptors αV and β3 chains had a mainly postacrosomal localization pattern. LFA-3 was found constantly on postacrosomal membrane areas. Double staining technique was used to prove the simultaneous occurrence of fibronectin and its integrin receptors α3, α4 and α5 chains and of αV and β2 chains on spermatozoa. The localization patterns of integrins on double stained spermatozoa were similar to the patterns described for single stained spermatozoa. The localization of fibronectin appeared to be influenced by the presence of integrins: the typical equatorial fibronectin band disappeared in case of an equatorial localization of integrins.  相似文献   
92.
We examined the relationship between testosterone levels, violent dreams, and REM sleep behavior disorder (RBD) in 31 men with Parkinson's disease (PD): 12 with clinical RBD and 19 without. All PD patients with clinical RBD experienced violent dreams, but none of the 19 non-RBD patients reported violent dreams. While dream content appears to be more aggressive in PD patients with clinical RBD, the presence of violent dreams or clinical RBD is not associated with testosterone levels in men with PD.  相似文献   
93.
Worksite health promotion programs have become increasinglyprevalent in the United States, and one or more health promotionprograms are found in two-thirds of all private worksites with50 or more employees. Reasons for recent growth in program frequencyinclude increased concern for worker health, rapidly escalatingemployer payments for health care benefits to workers, and growingevidence of a strong linkage between employee health and productivity.Published results of evaluations to date suggest that worksitehealth promotion programs can have positive impacts on healthbehaviors and health status. In addition, economic analysesare suggesting that some programs can affect the slope of healthcare costs and have the potential of high cost-effectivenesscompared to some clinical interventions. A number of researchchallenges remain, particularly understanding the influencesof the worksite environment and how employee health promotionprograms affect individual and organizational productivity.  相似文献   
94.
95.
96.
97.
Self-expanding nitinol stents were used in 22 patients for palliative treatment of malignant esophagogastric strictures. All patients but 5 were men (age range 47–75 years). The strictures were caused by squamous cell carcinoma (n = 12), adenocarcinoma (n = 8), and recurrent anastomotic carcinoma (n = 2). No technical failure or procedural complications occurred. After the procedure, the severity of dysphagia decreased at least one grade in all patients. Tumor ingrowth into the stent was seen in 7 patients of 22 (32%). Four of these patients were treated with additional stents, and in 3 patients, due to refusal, only balloon dilations were performed, which caused temporary relief. Tumor ingrowth into the stent was noted from 10 days to 7 months (mean 3 months). This seems to be a disadvantage of nitinol stents. At the end of the study 10 patients had died dead with a mean survival of 3 months (range 1 week to 6 months) and 12 patients were still alive with a mean follow-up of 4 months (range 1–8 months). It is concluded that nitinol stents provide satisfactory palliation in patients with malignant dysphagia with neglectable procedural morbidity and mortality rates.  相似文献   
98.
Intraperitoneal injection of inflammatory agents in the mouse and rat causes plasma protein and leukocyte extravasation into the peritoneal cavity. Following an intraperitoneal injection of zymosan A, the milky spots of the omentum were the only abdominal sites detected where intravenously administered Monastral Blue labeled interendothelial cell gaps responsible for plasma extravasation. In addition, when colored microspheres were intraventricularly administered to quantify blood flow, the omentum was the only abdominal organ which showed an increase in blood flow during zymosan A peritonitis. A combination of light and electron microscopy, plus measurement of myeloperoxidase activity (a marker of neutrophil accumulation) demonstrated that the omental milky spots are the major route through which leukocytes migrate into the peritoneal cavity. Identical structures in the pleura likewise are the sites of protein leakage into the pleural cavity. In contrast, selective sites of protein and cellular extravasation could not be detected in the synovial lining of the inflamed knee joint.  相似文献   
99.
Health-related quality of life (HQL) assessment in the clinical setting have distinguished subjective perceptions (e.g. well-being), signssymptoms of the disease, and functional capacity as three major components. The impact of short-term treatment for migraine attacks on these variables was evaluated in an open prospective 6-month study at the Gothenburg Migraine Clinic. Socio-economic factors, subjective symptoms, and general well-beingquality of life were evaluated by self-administered questionnaires in 99 patients with migraine with or without aura in accordance with the classification of the International Headache Society. Short-term treatment comprising conventional therapy or subcutaneous sumatriptan reduced number of days per month with migraine and absenteeism from work, migraine-associated symptoms, but did not significantly improve general well-being between attacks. Future assessment of the patients' HQL in accordance with this approach would enable us to consider all the advantages and disadvantages of current therapies of particular interest in the field of migraine.  相似文献   
100.
Forty-one cases of chondrosarcoma from varying sites throughout the body, and treated exclusively by one of the authors (R. L. H.) from 1972 to 1990 were reviewed. The symptoms, signs, location of tumours, treatment and progress are presented. Particular attention was paid to modular bone replacement techniques. Excision and reconstruction of the bone or joint were carried out in 17 femora, five tibia and six humeri. Comparison between this method of management and other techniques is discussed. Titanium and alumina prostheses for the hip, femur, tibia, shoulder and humerus have been designed by the senior author. These are both inert and modular, and have been found to be superior to other methods of treatment in both function and cosmesis. They do not possess the same potential donor infection risks and other disadvantages of allograft replacement. Immediate postoperative weight bearing and mobilization are possible with these systems. The Huckstep prostheses allow for bony in growth into their porous coated alumina sleeves, spacers and stems. In addition, the titanium alloy locking component for the femoral stems has an elasticity half that of other metal alloys and this was found to minimize stress shielding.  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