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   360464篇
  免费   22227篇
  国内免费   696篇
耳鼻咽喉   5035篇
儿科学   11911篇
妇产科学   11279篇
基础医学   53703篇
口腔科学   8564篇
临床医学   31248篇
内科学   67797篇
皮肤病学   7081篇
神经病学   26853篇
特种医学   14102篇
外国民族医学   45篇
外科学   57171篇
综合类   9332篇
现状与发展   2篇
一般理论   207篇
预防医学   25092篇
眼科学   8307篇
药学   25840篇
  29篇
中国医学   910篇
肿瘤学   18879篇
  2021年   4021篇
  2019年   3988篇
  2018年   5977篇
  2017年   4227篇
  2016年   4835篇
  2015年   5573篇
  2014年   7387篇
  2013年   10878篇
  2012年   13783篇
  2011年   13987篇
  2010年   9047篇
  2009年   7981篇
  2008年   12410篇
  2007年   13631篇
  2006年   13281篇
  2005年   12712篇
  2004年   11936篇
  2003年   11258篇
  2002年   10542篇
  2001年   14084篇
  2000年   14326篇
  1999年   12164篇
  1998年   3708篇
  1997年   3270篇
  1996年   3070篇
  1995年   2950篇
  1994年   2671篇
  1992年   8740篇
  1991年   8853篇
  1990年   8674篇
  1989年   8458篇
  1988年   7652篇
  1987年   7423篇
  1986年   7002篇
  1985年   6783篇
  1984年   5058篇
  1983年   4369篇
  1982年   2726篇
  1979年   4604篇
  1978年   3404篇
  1977年   2867篇
  1976年   2618篇
  1975年   2952篇
  1974年   3444篇
  1973年   3452篇
  1972年   3197篇
  1971年   3010篇
  1970年   2910篇
  1969年   2640篇
  1968年   2589篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
102.
Risk is a concept inherent in every medical procedure. It can be defined as the probability of an adverse event in a defined population over a specified period of time. In the frame of food allergy management, it might be related to a diagnostic procedure, a treatment, or the consumption of foods. The risk of an adverse event can also be augmented by individual factors. This rostrum article discusses various aspects faced by children with food allergies in the light of risk, and their practical implications. Identifying personal risks for severe reaction, such as unstable asthma, and correcting them whenever possible also contribute to a reduction of the risk inherent to food allergy. Among the facets discussed, oral food challenges (OFC) are the most common diagnostic procedures implying an inherent risk. The risk of OFCs can be minimized by correct indication and timing of the test, a safe setting, as well as by ensuring that the patient is otherwise well without potential stressor potentially increasing the risk of a more severe reaction. Oral immunotherapy (OIT) has been studied as a potential treatment for increasing the threshold dose for reaction, and thus reducing the risk of accidental reaction. Nevertheless, the procedure is not devoid of risk as the patients may and do often react during the course of the procedure. Ingestion of trace amounts in processed foods, mainly in community settings such as restaurants, schools, or day care, represents a potential risk of reactions, although for a minority of patients. Precautionary allergen labeling (PAL) is a widespread strategy to reduce the potential risk of reactions due to traces. However, PAL is currently inefficient due to inconsistent labeling, also not indicating a clear maximum amount possibly present in the manufactured food. Finally, cost-effectiveness needs to be considered in risk management, as many risk reduction procedures are clearly not cost-effective.  相似文献   
103.
104.
105.
106.
107.
108.
Jerry  A.  Shields  Ralph  C.  Eagle  Jr  Carol  L  Shields  Brian  P.  Marr  李学民 《美国医学会眼科杂志(中文版)》2006,18(1):33-39
众所周知,视网膜星形细胞瘤常伴有结节性硬化的表现。视网膜星形细胞瘤一般是发生在视网膜神经纤维层的无蒂轻度隆起性病变。临床上可以是单侧发生,也可以是双侧发生。可以单个病灶,也可以多个病灶。可以是透明的,也可以是不透明的。可以有钙化,也可以没有钙化。视网膜星形细胞瘤相对固定的伴有眼内结节性硬化,很少表现为浸润性增长。在很少的情况下视网膜星形细胞瘤可以表现出浸润性增长,造成局部严重并发症。  相似文献   
109.
Background The objective was to measure the plasma concentrations of thymulin and nerve growth factor (NGF) in a group of patients with primary open angle glaucoma (POAG) and compare them with age- and sex-matched normal controls.Methods Twenty-eight patients newly diagnosed with POAG who were not undergoing treatment were compared with the same number of age- and sex-matched healthy controls. Blood samples were drawn into heparinized tubes and plasma samples were collected for the determination of the concentrations of thymulin and NGF, using specific enzyme-linked immunosorbent assay (ELISA). The Student’s t test was used to perform the necessary statistical analysis of the results.Results Seventeen women and 11 men were enrolled in each of the two groups (study and control), with a mean age of 63.7 (SD 10.3) years in the former and 63.3 (SD 9.6) years in the latter. There was a highly significant (p<0.001) elevation in the thymulin levels in POAG patients compared with the control group. However, no significant difference was observed when comparing the plasma NGF levels.Conclusion This is the first report to measure plasma thymulin levels in glaucoma patients. The significant results point the possible role of this immunomodulator in the pathogenesis of primary open angle glaucoma. The potential role of NGF seems to be less likely. These findings warrant further investigation.  相似文献   
110.
Toby O. Smith   《Physiotherapy》2006,92(3):135-145
Pretibial lacerations and lower limb wounds are referred to plastic surgery teams for split skin graft surgery. Traditionally, these patients have been immobilised on bedrest following surgery. More recently, patients have commenced ambulation earlier to avoid medical complications and facilitate discharge. The objective of this literature review was to determine when such patients should begin walking. A literature search was undertaken using the electronic databases AMED, Cinahl, Embase, Medline (via Ovid), PEDro and Pubmed. Clinical trials using human subjects, written in English, were included. Seventeen (of 1137) papers met the inclusion criteria and were reviewed. The literature suggested that patients should begin walking immediately or at the earliest possible opportunity after lower limb skin graft surgery. Although the literature advocated early ambulation, the evidence base presented with a number of recurrent methodological limitations, including small sample sizes, lack of a control sample, and limited follow-up. Accordingly, further research employing large, well-designed, randomised controlled trials is recommended. It will then be possible to understand with greater certainty when patients should begin walking after lower extremity split skin graft surgery.  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