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   2421篇
  免费   142篇
  国内免费   18篇
耳鼻咽喉   21篇
儿科学   127篇
妇产科学   88篇
基础医学   238篇
口腔科学   43篇
临床医学   297篇
内科学   437篇
皮肤病学   35篇
神经病学   166篇
特种医学   229篇
外科学   284篇
综合类   45篇
一般理论   1篇
预防医学   266篇
眼科学   12篇
药学   140篇
中国医学   1篇
肿瘤学   151篇
  2021年   28篇
  2020年   18篇
  2019年   25篇
  2018年   34篇
  2017年   29篇
  2016年   27篇
  2015年   31篇
  2014年   45篇
  2013年   75篇
  2012年   107篇
  2011年   113篇
  2010年   62篇
  2009年   52篇
  2008年   82篇
  2007年   117篇
  2006年   92篇
  2005年   115篇
  2004年   85篇
  2003年   87篇
  2002年   92篇
  2001年   68篇
  2000年   80篇
  1999年   69篇
  1998年   52篇
  1997年   27篇
  1996年   33篇
  1995年   36篇
  1994年   32篇
  1993年   29篇
  1992年   65篇
  1991年   54篇
  1990年   56篇
  1989年   62篇
  1988年   67篇
  1987年   51篇
  1986年   43篇
  1985年   39篇
  1984年   37篇
  1983年   24篇
  1982年   23篇
  1981年   24篇
  1980年   25篇
  1979年   27篇
  1978年   19篇
  1977年   27篇
  1976年   21篇
  1975年   18篇
  1974年   19篇
  1970年   14篇
  1969年   13篇
排序方式: 共有2581条查询结果,搜索用时 15 毫秒
51.
52.
International Journal of Legal Medicine - Edged weapons are a known domestic threat to the police forces of the UK. This threat is mitigated by wearing stab-resistant body armour that is either...  相似文献   
53.
Despite the paucity of evidence, the practice of weaning nasal continuous positive airway pressure (NCPAP) is widespread. However, the most clinically effective non-invasive ventilatory support strategy remains to be determined. We compared the outcome of very premature infants with respiratory distress syndrome treated with a combination of NCPAP and heated humidified high-flow nasal cannula (HHFNC) versus NCPAP and low-flow nasal cannula (LFNC). Between 2004 and 2008, patients ≤28 weeks of gestation and <1,250 g of birth weight were treated with NCPAP + HHFNC or NCPAP + LFNC. Their respiratory and non-respiratory outcome including cost-effectiveness was compared after matching for antenatal steroid doses, mode of delivery, birth plurality, gestational age, birth weight, gender, surfactant doses, length of mechanical ventilation and clinical risk index for babies-II (CRIB-II) score. Thirty-nine infants received HHFNC + NCPAP, and 40 received NCPAP + LFNC. Median gestational age and birth weight were 27 weeks and 930 g and 27 weeks and 980 g, respectively. The total number of NCPAP days was significantly reduced by 50 % in the HHFNC group. Thirteen percent of the patients on NCPAP suffered from nasal bridge lesions compared to none on HHFNC. Respiratory and non-respiratory outcome was not significantly different otherwise. Combination of NCPAP and HHFNC reduced costs by 33 %. Conclusions: HHFNC shortens NCPAP time without increasing overall length of non-invasive respiratory support in very preterm infants. Unlike NCPAP, HHFNC does not seem to increase the risk of nasal trauma and appears to improve cost-effectiveness whilst producing otherwise equal respiratory and non-respiratory outcomes.  相似文献   
54.
Beverages contribute significantly to dietary intake. Research exploring the impact of beverage types on nutrient intake for Australian Aboriginal and Torres Strait Islander people is limited. A secondary analysis of the Australian Aboriginal and Torres Strait Islander Health Survey 2012–2013 (n = 4109) was undertaken. The daily intake, percentage of consumers, and contribution to total nutrient intake was estimated for 12 beverage categories. Beverage intake contributed to 17.4% of total energy, 27.0% of total calcium, 26.3% of total vitamin C, and 46.6% of total sugar intake. The most frequently consumed beverage categories for children (aged 2 to 18 years) were water, fruit juice/drinks, soft drinks, and cordial; and for adults, water, tea, coffee and soft drinks. The primary sources of beverages with added sugar were fruit juice/drinks (for children), tea (for people living remotely), coffee (for adults in metropolitan/regional areas) and soft drinks (for everyone). Actions to modify beverage intake to improve health should maintain the positive nutrient attributes of beverage intake. This analysis of a large-scale national dietary survey provides benchmarking of beverage intake to support program and policy development to modify intake where this is determined as a priority by the community.  相似文献   
55.
Serological identification of thymocyte differentiation antigens   总被引:1,自引:0,他引:1  
We have examined subfractions of human thymocytes for the expression of novel differentiation antigens. Non-HLA alloantisera procured from multiparous women served as antibody probes. Thymocytes from five individuals were sequentially separated by discontinuous Percoll density gradient centrifugation and a peanut agglutinin (PNA) panning technique. Subfractions were selected and examined for their relative intensity of HLA class I and CD1 antigens as determined by cytofluorometric analysis. Two subfractions were characterized as follows: an immature population (Fr6 PNA-) expressed a high level of CD1 (OKT6 binding) antigen and a low level of class I HLA antigen; and a more mature fraction (Fr3 PNA-) expressed minimal amounts of CD1 antigen and relatively high levels of HLA class I molecules. Fr6 PNA+ and Fr3 PNA- thymocytes were tested for their reactivity with a panel of non-HLA alloantibodies as determined by cytofluorometric analysis. We observed that three alloantibodies demonstrated strong fluorescence staining with Fr6 PNA+ thymocytes only, whereas three other alloantibodies reacted with both the Fr6 PNA+ and the Fr3 PNA- subfractions. All six alloantibodies failed to react with peripheral T cells. However, the six antibodies did react with a panel of cultured T lymphoblastoid leukemic cells and fresh leukemic T cells. Blocking studies demonstrated that these alloantibodies do not bind beta 2-microglobulin-associated determinants. These results suggest that the alloantibodies detect thymocyte differentiation antigens (TDA) that are shared by or are cross-reactive with antigens expressed on certain leukemia T cells. The non-beta 2m-associated TDA antigens are not expressed on normal resting T cells.  相似文献   
56.
57.
Immunogenicity in humans of an edible vaccine for hepatitis B   总被引:21,自引:0,他引:21       下载免费PDF全文
A double-blind placebo-controlled clinical trial evaluated the immunogenicity of hepatitis B surface antigen (HBsAg) expressed in potatoes and delivered orally to previously vaccinated individuals. The potatoes accumulated HBsAg at approximately 8.5 microg/g of potato tuber, and doses of 100 g of tuber were administered by ingestion. The correlate of protection for hepatitis B virus, a nonenteric pathogen, is blood serum antibody titers against HBsAg. After volunteers ate uncooked potatoes, serum anti-HBsAg titers increased in 10 of 16 volunteers (62.5%) who ate three doses of potatoes; in 9 of 17 volunteers (52.9%) who ate two doses of transgenic potatoes; and in none of the volunteers who ate nontransgenic potatoes. These results were achieved without the coadministration of a mucosal adjuvant or the need for buffering stomach pH. We conclude that a plant-derived orally delivered vaccine for prevention of hepatitis B virus should be considered as a viable component of a global immunization program.  相似文献   
58.
59.
60.
The role of FoxC1 in early Xenopus development.   总被引:1,自引:0,他引:1  
  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