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   1500148篇
  免费   108199篇
  国内免费   3003篇
耳鼻咽喉   20694篇
儿科学   48145篇
妇产科学   41816篇
基础医学   216199篇
口腔科学   39589篇
临床医学   130870篇
内科学   298091篇
皮肤病学   29593篇
神经病学   120938篇
特种医学   57451篇
外国民族医学   377篇
外科学   230822篇
综合类   29622篇
现状与发展   1篇
一般理论   613篇
预防医学   112278篇
眼科学   34914篇
药学   112991篇
  7篇
中国医学   2771篇
肿瘤学   83568篇
  2021年   12236篇
  2019年   12752篇
  2018年   17112篇
  2017年   12932篇
  2016年   14450篇
  2015年   16771篇
  2014年   23577篇
  2013年   34937篇
  2012年   49459篇
  2011年   52593篇
  2010年   30618篇
  2009年   28386篇
  2008年   49598篇
  2007年   53338篇
  2006年   53832篇
  2005年   53026篇
  2004年   50724篇
  2003年   48629篇
  2002年   47325篇
  2001年   59979篇
  2000年   60997篇
  1999年   52721篇
  1998年   16970篇
  1997年   15055篇
  1996年   15011篇
  1995年   14200篇
  1994年   13338篇
  1993年   12238篇
  1992年   42114篇
  1991年   41365篇
  1990年   40767篇
  1989年   39572篇
  1988年   36972篇
  1987年   36173篇
  1986年   34557篇
  1985年   32983篇
  1984年   25019篇
  1983年   21826篇
  1982年   13600篇
  1979年   23256篇
  1978年   16555篇
  1977年   14302篇
  1976年   13505篇
  1975年   14621篇
  1974年   17100篇
  1973年   16423篇
  1972年   15613篇
  1971年   14473篇
  1970年   13427篇
  1969年   12885篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.

Objective

To determine whether differences in combination DTaP vaccine types at 2, 4 and 6?months of age were associated with mortality (all-cause or non-specific), within 30?days of vaccination.

Design

Observational nationwide cohort study.

Setting

Linked population data from the Australian Childhood Immunisation Register and National Death Index.

Participants

Australian infants administered a combination trivalent, quadrivalent or hexavalent DTaP vaccine (DTaP types) between January 1999 and December 2010 at 2, 4 and 6?months as part of the primary vaccination series. The study population included 2.9, 2.6, & 2.3?million children in the 2, 4 and 6?month vaccine cohorts, respectively.

Main outcome measures

Infants were evaluated for the primary outcome of all-cause mortality within 30?days. A secondary outcome was non-specific mortality (unknown cause of death) within 30?days of vaccination. Non-specific mortality was defined as underlying or other cause of death codes, R95 ‘Sudden infant death syndrome’, R96 ‘Other sudden death, cause unknown’, R98 ‘Unattended death’, R99 ‘Other ill-defined and unspecified cause of mortality’ or where no cause of death was recorded.

Results

The rate of 30?day all-cause mortality was low and declined from 127.4 to 59.3 deaths per 100,000 person-years between 2 and 6?month cohorts. When compared with trivalent DTaP vaccines, no elevated risk in all-cause or non-specific mortality was seen with any quadrivalent or hexavalent DTaP vaccines, for any cohort.

Conclusion

Use of routine DTaP combination vaccines with differing disease antigens administered during the first six months of life is not associated with infant mortality.  相似文献   
102.
Pulse oximetry is used widely to titrate oxygen therapy and for triage in patients who are critically ill. However, there are concerns regarding the accuracy of pulse oximetry in patients with COVID-19 pneumonitis and in patients who have a greater degree of skin pigmentation. We aimed to determine the impact of patient ethnicity on the accuracy of peripheral pulse oximetry in patients who were critically ill with COVID-19 pneumonitis by conducting a retrospective observational study comparing paired measurements of arterial oxygen saturation measured by co-oximetry on arterial blood gas analysis (SaO2) and the corresponding peripheral oxygenation saturation measured by pulse oximetry (SpO2). Bias was calculated as the mean difference between SaO2 and SpO2 measurements and limits of agreement were calculated as bias ±1.96 SD. Data from 194 patients (135 White ethnic origin, 34 Asian ethnic origin, 19 Black ethnic origin and 6 other ethnic origin) were analysed consisting of 6216 paired SaO2 and SpO2 measurements. Bias (limits of agreement) between SaO2 and SpO2 measurements was 0.05% (−2.21–2.30). Patient ethnicity did not alter this to a clinically significant degree: 0.28% (1.79–2.35), −0.33% (−2.47–2.35) and −0.75% (−3.47–1.97) for patients of White, Asian and Black ethnic origin, respectively. In patients with COVID-19 pneumonitis, SpO2 measurements showed a level of agreement with SaO2 values that was in line with previous work, and this was not affected by patient ethnicity.  相似文献   
103.
European Journal of Clinical Microbiology & Infectious Diseases - We compared the performance of an in-house-developed flow cytometry assay for intracellular cytokine staining (FC-ICS) and a...  相似文献   
104.
105.
106.
107.
Neutrophils can form neutrophil extracellular traps (NETs) to capture microbes and facilitate their clearance. NETs consist of decondensed chromatin decorated with anti-microbial proteins. Here, we describe the effect of neutrophil proteases on the protein content of NETs. We show that the neutrophil serine proteases degrade several neutrophil proteins associated with NETs. Interestingly, the anti-bacterial proteins associated with NETs, such as myeloperoxidase, calgranulin B and neutrophil elastase (NE), seem to be less susceptible to proteolytic degradation than other NET proteins, such as actin and MNDA. NETs have been proposed to play a role in autoimmune reactions. Our data demonstrate that a large number of the autoepitopes of NET proteins that are recognized by autoantibodies produced by systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) patients are also removed by the proteases. In conclusion, neutrophil serine proteases have a major impact on the NET proteome and the proteolytic changes of NET-associated proteins may counteract autoimmune reactions to NET components.  相似文献   
108.
Ovarian cancer is the fourth most common cause of cancer-related death in women in the developed world, and one of the most heritable cancers. One of the most significant risk factors for epithelial ovarian cancer (EOC) is a family history of breast and/or ovarian cancer. Combined risk factors can be used in models to stratify risk of EOC, and aid in decisions regarding risk-reduction strategies. Germline pathogenic variants in EOC susceptibility genes including those involved in homologous recombination and mismatch repair pathways are present in approximately 22% to 25% of EOC. These genes are associated with an estimated lifetime risk of EOC of 13% to 60% for BRCA1 variants and 10% to 25% for BRCA2 variants, with lower risks associated with remaining genes. Genome-wide association studies have identified single nucleotide polymorphisms (SNPs) thought to explain an additional 6.4% of the familial risk of ovarian cancer, with 34 susceptibility loci identified to date. However, an unknown proportion of the genetic component of EOC risk remains unexplained. This review comprises an overview of individual genes and SNPs suspected to contribute to risk of EOC, and discusses use of a polygenic risk score to predict individual cancer risk more accurately.  相似文献   
109.
IntroductionPain is highly prevalent in patients with multiple sclerosis (MS); it is chronic in 50% of cases and is classified as nociceptive, neuropathic, or mixed-type. Pain affects quality of life, sleep, and the activities of daily living. Electrotherapy is an interesting alternative or complementary treatment in the management of pain in MS, with new innovations constantly appearing.Material and methodsThis study evaluates the effectiveness of treatment with monopolar dielectric transmission of pulsed electromagnetic fields (PEMF) for pain associated with MS. We performed a randomised, placebo-controlled clinical trial including 24 patients, who were assessed with the Brief Pain Inventory, the Multiple Sclerosis International Quality of Life questionnaire, the Beck Depression Inventory, and the Modified Fatigue Impact Scale.ResultsStatistically significant improvements were observed in maximum and mean pain scores, as well as in the impact of pain on work, personal relationships, and sleep and rest. Not significant differences were found between the treatment and placebo groups.ConclusionsTreatment with PEMF may be effective in reducing pain in patients with MS, although further research is necessary to confirm its effectiveness over placebo and to differentiate which type of pain may be more susceptible to this treatment.  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