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   1288099篇
  免费   87024篇
  国内免费   1960篇
耳鼻咽喉   18271篇
儿科学   42363篇
妇产科学   37889篇
基础医学   187889篇
口腔科学   35455篇
临床医学   108667篇
内科学   252677篇
皮肤病学   26572篇
神经病学   99829篇
特种医学   50168篇
外国民族医学   367篇
外科学   198281篇
综合类   26541篇
现状与发展   1篇
一般理论   300篇
预防医学   92822篇
眼科学   29164篇
药学   98074篇
  18篇
中国医学   2519篇
肿瘤学   69216篇
  2018年   11907篇
  2015年   11698篇
  2014年   16099篇
  2013年   24493篇
  2012年   33708篇
  2011年   36117篇
  2010年   21331篇
  2009年   20169篇
  2008年   35175篇
  2007年   38152篇
  2006年   38712篇
  2005年   37958篇
  2004年   36549篇
  2003年   35513篇
  2002年   35133篇
  2001年   58243篇
  2000年   59737篇
  1999年   50839篇
  1998年   14289篇
  1997年   12849篇
  1996年   13099篇
  1995年   12366篇
  1994年   11785篇
  1993年   10880篇
  1992年   41041篇
  1991年   40413篇
  1990年   39918篇
  1989年   38757篇
  1988年   36151篇
  1987年   35382篇
  1986年   33766篇
  1985年   32172篇
  1984年   23949篇
  1983年   20846篇
  1982年   12388篇
  1981年   10936篇
  1980年   10220篇
  1979年   22655篇
  1978年   15890篇
  1977年   13737篇
  1976年   12976篇
  1975年   14224篇
  1974年   16691篇
  1973年   16079篇
  1972年   15333篇
  1971年   14240篇
  1970年   13223篇
  1969年   12741篇
  1968年   11982篇
  1967年   10490篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.

Background

Lung cancer screening can reduce cancer mortality. Most implementation studies focus only on low-dose computed tomography (LDCT) and clinical attributes of screening and do not include preferences of potential participants. In this study we evaluated the perceived value of screening programs based on LDCT, breath analysis (BA), or blood biomarkers (BB) according to the perspective of the target population.

Methods

A multi-criteria decision analysis framework was adopted. The weights of seven attributes of screening (sensitivity, specificity, radiation burden, duration of screening process, waiting time until results are communicated, location of screening, and mode of screening) were obtained from an earlier study that included a broad sample from the Netherlands. Performance data for the screening modalities was obtained from clinical trials and expert opinion. Parameter uncertainty about clinical performances was incorporated probabilistically, while heterogeneity in preferences was analyzed through subgroup analyses.

Results

The mean overall values were 0.58 (CI: 0.57 to 0.59), 0.57 (CI: 0.56 to 0.59), and 0.44 (CI: 0.43 to 0.45) for BB, BA, and LDCT, respectively. Seventy-seven per cent of respondents preferred BB or BA. For most subgroups, the overall values were similar to those of the entire sample. BA had the highest value for respondents who would have been eligible for earlier screening trials.

Discussion

BB and BA seem valuable to participants because they can be applied in a primary care setting. Although LDCT still seems preferable given its strong and positive evidence base, it is important to take non-clinical attributes into account to maximize attendance.  相似文献   
103.
Maternal and Child Health Journal - Objective The association between and commonality of risk factors for poor self-rated oral health (SROH) and general health (SRGH) among new mothers has not been...  相似文献   
104.
105.
106.
107.
Investigators postulated that early-life exposure to organic mercury (Hg) significantly increases the risk of childhood neurodevelopmental disorders (NDs). The Vaccine Adverse Event Reporting System database was utilized to conduct a hypothesis testing case-control study by evaluating 3486 total adverse event reports reported following Haemophilus influenza type b (Hib) vaccination. Exposed subjects received a Thimerosal-containing formulation (HIBTITER?, Wyeth-Lederle), while unexposed subjects received a Thimerosal-free formulation (PEDVAXHIB?, Merck). Subjects were included if they received either of these two Hib vaccine formulations between 1995 and 1999. Cases were defined as adverse event reports with a reported outcome of autism, developmental delay, psychomotor delay, or NDs in general. Cases with reported outcomes of febrile convulsions, pyrexia, or injection site pain, all of which have no biologically plausible relation to Hg exposure, were also examined. Controls were defined as adverse event reports without any mention of the specific case outcome examined. Cases of reported autism (odds ratio (OR)?=?2.75, p?<?0.02), developmental delay (OR?=?5.39, p?<?0.01), psychomotor disorder (OR?=?2.38, p?<?0.03), and neurodevelopmental disorder in general (OR?=?2.70, p?<?0.001) were each significantly more likely than their respective controls to receive Thimerosal-containing Hib vaccine than Thimerosal-free Hib vaccine. Significant effects for neurodevelopmental disorder in general were observed for males (OR?=?2.52, p?<?0.005), but not females when separated by gender. For the outcomes that had no biologically plausible relation to Hg exposure, the cases were no more likely than their respective controls to receive Thimerosal-containing Hib vaccine than Thimerosal-free Hib vaccine. This study provides suggestive evidence of an association between Thimerosal and neurodevelopmental outcomes and provides support for carrying out additional well-designed studies examining the association between Thimerosal-containing vaccines and a wide range of neurodevelopmental outcomes.  相似文献   
108.
109.
Sewage contains a mixed ecosystem of diverse sets of microorganisms, including human pathogenic viruses. Little is known about how conventional as well as advanced treatments of sewage, such as ozonation, reduce the environmental spread of viruses. Analyses for viruses were therefore conducted for three weeks in influent, after conventional treatment, after additional ozonation, and after passing an open dam system at a full-scale treatment plant in Knivsta, Sweden. Viruses were concentrated by adsorption to a positively charged filter, from which they were eluted and pelleted by ultracentrifugation, with a recovery of about 10%. Ion Torrent sequencing was used to analyze influent, leading to the identification of at least 327 viral species, most of which belonged to 25 families with some having unclear classification. Real-time PCR was used to test for 21 human-related viruses in inlet, conventionally treated, and ozone-treated sewage and outlet waters. The viruses identified in influent and further analyzed were adenovirus, norovirus, sapovirus, parechovirus, hepatitis E virus, astrovirus, pecovirus, picobirnavirus, parvovirus, and gokushovirus. Conventional treatment reduced viral concentrations by one to four log10, with the exception of adenovirus and parvovirus, for which the removal was less efficient. Ozone treatment led to a further reduction by one to two log10, but less for adenovirus. This study showed that the amount of all viruses was reduced by conventional sewage treatment. Further ozonation reduced the amounts of several viruses to undetectable levels, indicating that this is a promising technique for reducing the transmission of many pathogenic human viruses.  相似文献   
110.
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