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   4426篇
  免费   313篇
  国内免费   9篇
耳鼻咽喉   25篇
儿科学   162篇
妇产科学   183篇
基础医学   586篇
口腔科学   91篇
临床医学   371篇
内科学   882篇
皮肤病学   32篇
神经病学   600篇
特种医学   566篇
外科学   469篇
综合类   100篇
一般理论   1篇
预防医学   215篇
眼科学   73篇
药学   201篇
  1篇
肿瘤学   190篇
  2021年   46篇
  2018年   36篇
  2017年   46篇
  2016年   43篇
  2015年   53篇
  2014年   82篇
  2013年   106篇
  2012年   112篇
  2011年   138篇
  2010年   95篇
  2009年   92篇
  2008年   144篇
  2007年   143篇
  2006年   189篇
  2005年   157篇
  2004年   140篇
  2003年   135篇
  2002年   117篇
  2001年   120篇
  2000年   119篇
  1999年   116篇
  1998年   110篇
  1997年   108篇
  1996年   111篇
  1995年   93篇
  1994年   66篇
  1993年   78篇
  1992年   110篇
  1991年   102篇
  1990年   115篇
  1989年   124篇
  1988年   102篇
  1987年   109篇
  1986年   115篇
  1985年   124篇
  1984年   90篇
  1983年   76篇
  1982年   65篇
  1981年   53篇
  1980年   70篇
  1979年   62篇
  1978年   61篇
  1977年   59篇
  1976年   64篇
  1975年   56篇
  1974年   46篇
  1973年   42篇
  1971年   35篇
  1970年   40篇
  1969年   31篇
排序方式: 共有4748条查询结果,搜索用时 15 毫秒
1.
Isolated patellofemoral arthritis is an increasingly recognized entity, and is usually associated with previous patellofemoral dysplasia or instability. Patellofemoral arthroplasty (PFA) has evolved significantly in recent years, both in terms of implant design and importantly in the understanding of appropriate patient selection. This review outlines the indications and investigations for PFA, provides a brief history of the development of contemporary implants, and presents the clinical outcomes for the prostheses most commonly used in the UK. In addition, it provides a detailed surgical technique for implantation of an onlay implant, with tips on how to optimize patellofemoral biomechanics and thus achieve a consistently good outcome.  相似文献   
2.
Animal and human studies suggest fish oil and green tea may have protective effect on prostate cancer. Fatty acid synthase (FAS) has been hypothesized to be linked to chemoprotective effects of both compounds. This study evaluated the independent and joint effects of fish oil (FO) and green tea supplement (epigallocatechin-3-gallate, EGCG) on FAS and Ki-67 levels in prostate tissue. Through a double-blinded, randomized controlled trial with 2 × 2 factorial design, 89 men scheduled for repeat prostate biopsy following an initial negative prostate biopsy were randomized into either FO alone (1.9 g DHA + EPA/day), EGCG alone (600 mg/day), a combination of FO and EGCG, or placebo. We used linear mixed-effects models to test the differences of prostate tissue FAS and Ki-67 by immunohistochemistry between pre- and post-intervention within each group, as well as between treatment groups. Results did not show significant difference among treatment groups in pre-to-post-intervention changes of FAS (P = 0.69) or Ki-67 (P = 0.26). Comparing placebo group with any of the treatment groups, we did not find significant difference in FAS or Ki-67 changes (all P > 0.05). Results indicate FO or EGCG supplementation for a short duration may not be sufficient to produce biologically meaningful changes in FAS or Ki-67 levels in prostate tissue.  相似文献   
3.
BACKGROUND: Few data are currently available investigating neurosteroids (NS) in Alzheimer's disease (AD). The NS allopregnanolone may be decreased in serum and plasma in patients with AD, but it is unclear if allopregnanolone is also reduced in brain. Because a number of NS exhibit neuroprotective effects and impact cognitive performance in rodent models, these molecules may be relevant to the pathophysiology of neurodegenerative disorders. We therefore investigated prefrontal cortex (PFC) NS levels in AD. METHODS: Neurosteroid levels (allopregnanolone, pregnenolone, dehydroepiandrosterone [DHEA]) were determined in postmortem PFC in 14 male subjects with AD and 15 cognitively intact male control subjects by gas chromatography/mass spectrometry preceded by high-performance liquid chromatography purification. RESULTS: Subjects with AD exhibit significant reductions in allopregnanolone compared with cognitively intact control subjects (median levels = 2.50 ng/g vs. 5.59 ng/g, respectively; p = .02). Allopregnanolone levels are inversely correlated with neuropathological disease stage (Braak), r = -.49, p = .007. Median DHEA levels are elevated in subjects with AD (p = .01). CONCLUSIONS: Subjects with AD demonstrate significant reductions in PFC allopregnanolone levels, a finding that may be relevant to neuropathological disease stage severity. Neurosteroids may have utility as candidate biomarkers in AD.  相似文献   
4.
5.
Pseudomonas aeruginosa ribosomal vaccines were tested for their ability to protect rats subjected to a 20% total body surface burn against the lethal effects of infection with homologous organisms. When administered prior to burning, the vaccines provided 100% protection. When administered postburning, the vaccine from one strain also provided 100% protection when the time interval between vaccination and infection was 3 days. When this time interval was reduced to 1 or 2 days, approximately 50% protection was obtained with the same vaccine. The vaccine from a second strain tested provided about 50% protection with a 3-day time interval. In addition, passive immunization using antiserum to a ribosomal vaccine was also demonstrated to be effective in protecting burned and infected rats, especially when multiple doses of antiserum were used. In this case, 80% protection was obtained (with no protection observed using multiple doses of normal serum). Finally, a comparison of ribosomal and lipopolysaccharide vaccines and antisera was also performed.  相似文献   
6.
Legal uncertainties for emergency vehicle drivers can be avoided when fundamental rules are established. In particular, differentiation of special rights and rights of way is essential. Inherent in both is the urgency necessary to save human lives. The right of way signaled by flashing blue lights and siren does not however justify traffic violations but signifies rather a request to other traffic participants. In contrast, special rights require no announcement and constitute a justifiable reason for traffic violations. Even so they do not allow that other traffic participants be endangered or harmed. Adherence to these basic principles can prevent legal misinterpretations as well as rigid adoption of inflexible standards of behavior.  相似文献   
7.
Austria’s new Living Wills Act (Patientenverfügungsgesetz, or PatVG) that came into effect on 1st of June 2006, is the first law in Austria to regulate the controversial issue of living wills. The PatVG provides for a right to refuse future medical treatment by making an advance directive in the form of a living will that is either binding or “to be taken into consideration”. However, the establishment of a binding living will is governed by strict criteria as regards form and content, and both a medical doctor and a legal expert must be involved. Compliance with a living will is not allowed where there is a legal obligation to give medical treatment. There is also a legal obligation to give medical treatment in emergency situations where the time involved in looking for a living will could seriously endanger the health or the life of a patient.  相似文献   
8.
9.
10.
Follow up MRI study in first episode schizophrenia.   总被引:2,自引:0,他引:2  
  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