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   47914篇
  免费   2569篇
  国内免费   224篇
耳鼻咽喉   757篇
儿科学   2040篇
妇产科学   1361篇
基础医学   4391篇
口腔科学   1827篇
临床医学   4106篇
内科学   9684篇
皮肤病学   1000篇
神经病学   2994篇
特种医学   1717篇
外国民族医学   4篇
外科学   9481篇
综合类   919篇
现状与发展   3篇
一般理论   33篇
预防医学   2792篇
眼科学   1701篇
药学   3459篇
  1篇
中国医学   342篇
肿瘤学   2095篇
  2024年   54篇
  2023年   549篇
  2022年   1113篇
  2021年   1784篇
  2020年   1109篇
  2019年   1400篇
  2018年   1864篇
  2017年   1379篇
  2016年   1523篇
  2015年   1568篇
  2014年   2021篇
  2013年   2553篇
  2012年   3746篇
  2011年   3852篇
  2010年   2117篇
  2009年   1696篇
  2008年   2816篇
  2007年   3043篇
  2006年   2776篇
  2005年   2642篇
  2004年   2382篇
  2003年   2073篇
  2002年   1852篇
  2001年   714篇
  2000年   748篇
  1999年   536篇
  1998年   285篇
  1997年   194篇
  1996年   193篇
  1995年   142篇
  1994年   119篇
  1993年   93篇
  1992年   169篇
  1991年   174篇
  1990年   138篇
  1989年   128篇
  1988年   110篇
  1987年   102篇
  1986年   93篇
  1985年   121篇
  1984年   77篇
  1983年   57篇
  1982年   56篇
  1981年   58篇
  1980年   45篇
  1979年   58篇
  1978年   50篇
  1977年   37篇
  1976年   39篇
  1974年   43篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Flow-directed pulmonary artery catheters provide important information regarding intravascular volume status, cardiac function and vascular resistance. We describe an unusual complication of pulmonary artery catheterization in which a knot formed at the distal end was torn away from the catheter body and migrated from its original position in the right subclavian vein to a distal branch of the right pulmonary artery. Careful attention to insertion and withdrawal techniques could prevent this potentially serious complication.  相似文献   
52.
53.
54.
Ten patients with complex non-union of the tibia were treated by locked intramedullary nailing. These patients had scarred skin as a result of initial severe open fractures, multiple debridement or fasciotomies with external fixators and skin grafts applied. Seven of the patients also had previous osteomyelitis or pin track infections. Fully pain-free walking was achieved in all patients and radiological union in nine patients without the need for a bone graft. Four patients developed infection after nailing, of which three resolved with treatment.  相似文献   
55.
56.
INTRODUCTION: Reconstructive septorhinoplasty in complex nasal deformities often requires harvesting a large amount of tissue for grafting. Autogenous septal cartilage has generally been considered the gold standard grafting material. The aim of this paper was to report our experience with the use of costal cartilage grafts in cases with significant structural deformities and insufficient septal cartilage. DESIGN: Retrospective chart review. PATIENTS: Between 1998 and 2006, 37 patients underwent septorhinoplasty using costal cartilage as the primary source for grafting. Twenty-two men and 14 women with a median age of 42 were enrolled in the study. Patient demographics, indications for surgery, and immediate and late complications were reviewed. The follow-up range was 3 to 72 months. CONCLUSIONS: Autogenous costal cartilage graft is a viable option in reconstructive septorhinoplasty. We advocate the use of this graft in septorhinoplasty cases requiring a large volume of tissue and insufficient septal cartilage.  相似文献   
57.
Summary A recombinant vaccinia virus designated VgBt which expresses a truncated secreted herpes simplex virus gB (gBt) was constructed and compared to V11gB, a vaccinia recombinant previously studied which expresses gB exclusively on the surface of infected cells. Indirect immunofluorescence assay (IFA) revealed that gBt was strongly associated with the surface of infected cells despite being released slowly into the cell culture medium. Both gB and gBt existed as oligomers, and both membrane bound and secreted forms of gBt exhibited heparin-binding activity. In protection studies VgBt and V11gB conferred equivalent protection against both homologous (HSV-1) and heterologous (HSV-2) challenge with HSV.  相似文献   
58.
A new dimeric indoline alkaloid has been isolated from the leaves of PETCHIA CEYLANICA. Its structure has been assigned as 1 on the basis of spectral studies. Its stereochemistry has been established by NOE difference measurements.  相似文献   
59.
Chronic exposure to cannabis extract or delta-9-tetrahydrocannabinol (THC) has been reported to produce hippocampal neuropathology in rats, as well as classical "hippocampal" behavioral deficits. In an attempt to replicate and extend these findings, male rats were exposed to THC for 13 consecutive weeks, beginning in early adolescence. Drugs were administered five consecutive days a week (Monday through Friday). There were five dose levels: vehicle control, 5, 10, or 20 mg/kg, p.o., and 20 mg/kg THC four days a week (Monday-Thursday), followed by 60 mg/kg on Friday. Following THC exposure, all animals were withdrawn from drugs for seven weeks prior to behavioral testing. Three behavioral tasks previously shown to be sensitive to hippocampal damage were assessed. These were habituation of open-field activity, 24-hr passive avoidance response retention, and complex maze performance. A fourth task, emergence latency, was also included because it has been determined to be sensitive to "anxiety" levels. To facilitate interpretation of the complex maze data, two additional experiments are also reported. One experiment tested rats exposed to trimethyltin (TMT, a potent hippocampal neurotoxicant) on the complex maze. The second assessed the affects of chronic/acute benzodiazepine (BZ) exposure upon maze performance. Test results did not suggest that chronic THC exposure produced behavioral deficits resembling those seen following hippocampal damage. Habituation rates in an activity monitor were identical for all exposure groups, and there was no passive avoidance retention deficit. Further, while TMT caused pronounced abnormalities in the complex maze, chronic THC exposure at the two highest dose levels significantly improved maze performance, similar to BZ effects on this task. Chronic THC also appeared to reduce freezing on the emergence task, another anxiolytic-like effect. These results support other reports of persistent long-term behavioral effects of chronic THC exposure. However, they suggest that some behavioral effects may more closely resemble the effects of minor tranquilizers rather than hippocampal damage.  相似文献   
60.
Health and nutrition education involves not only conveying new information and concepts, but also persuading the target population to engage in innovative action and direct participation. This process can be thwarted if cultural factors are ignored, particularly in dealing with a tribal population. In a country like India, communication with tribals is influenced by ethnic and cultural diversities, different types of ecological settings, a low literacy level, geographic isolation, the lack of development infrastructure, language barriers, health taboos and problems, a lack of access to modern media forms, and food availability and use. Most suitable for working with tribal populations appear to be the media of the spoken work, song and drama, games, exhibitions at the weekly market and yearly festivals, and pictorial aids. Since communication is a 2-way process, there must be a shared frame of reference among scientists, communicators, and receivers. Moreover, even when health education messages are delivered through culture-specific entertainment programs, they must be part of a comprehensive health and development package in which extension workers are backed up by health professionals and integrated programs.  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