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   4514篇
  免费   281篇
  国内免费   14篇
耳鼻咽喉   52篇
儿科学   85篇
妇产科学   62篇
基础医学   690篇
口腔科学   56篇
临床医学   398篇
内科学   1249篇
皮肤病学   33篇
神经病学   504篇
特种医学   323篇
外科学   554篇
综合类   7篇
一般理论   6篇
预防医学   248篇
眼科学   84篇
药学   238篇
中国医学   1篇
肿瘤学   219篇
  2024年   6篇
  2023年   38篇
  2022年   85篇
  2021年   142篇
  2020年   105篇
  2019年   140篇
  2018年   151篇
  2017年   114篇
  2016年   135篇
  2015年   148篇
  2014年   193篇
  2013年   220篇
  2012年   387篇
  2011年   388篇
  2010年   264篇
  2009年   231篇
  2008年   315篇
  2007年   357篇
  2006年   311篇
  2005年   281篇
  2004年   223篇
  2003年   199篇
  2002年   159篇
  2001年   29篇
  2000年   18篇
  1999年   23篇
  1998年   26篇
  1997年   21篇
  1996年   15篇
  1995年   14篇
  1994年   2篇
  1993年   7篇
  1992年   5篇
  1991年   2篇
  1988年   3篇
  1987年   2篇
  1986年   4篇
  1985年   3篇
  1984年   3篇
  1978年   3篇
  1977年   4篇
  1975年   4篇
  1974年   5篇
  1973年   3篇
  1968年   2篇
  1967年   4篇
  1966年   2篇
  1961年   2篇
  1955年   1篇
  1949年   1篇
排序方式: 共有4809条查询结果,搜索用时 15 毫秒
991.
Clinical Oral Investigations - The aims of this study are to assess different saliva substitutes for their efficacy to lubricate the oral cavity, and to relate this oral lubrication to the ability...  相似文献   
992.
Haemostatic treatment in women experiencing postpartum haemorrhage is increasingly based on point-of-care devices such as ROTEM® thromboelastometry. Recently, a fully automated successor of the ROTEM® Delta device, the ROTEM® Sigma was introduced. To determine whether these devices provide similar results, we compared ROTEM® parameters using the ROTEM® Delta and Sigma devices in women experiencing postpartum haemorrhage. Prospective observational cohort study of 23 women experiencing postpartum haemorrhage. ROTEM® INTEM, EXTEM, FIBTEM and APTEM measurements handled by the ROTEM® Delta and Sigma devices were compared. ROTEM® FIBTEM values were also related to Clauss fibrinogen values. A correlation of Spearman’s r (rs) varying between 0.76 and 0.95 was displayed between clot firmness measured in millimeters at 5 (A5), 10 (A10) and 20 (A20) minutes after start of clot formation measured by EXTEM, INTEM and APTEM assays executed on both devices; A5, A10 and A20 of FIBTEM correlated less well (rS between 0.71 and 0.74), especially after five and ten minutes. Correlation between both devices regarding clotting time (CT) was poor. The observed correlation between levels of Clauss fibrinogen and FIBTEM A5 was rs = 0.70, (95% confidence interval (CI): 0.38 to 0.87) for Delta and rs = 0.85, (CI 0.65 to 0.94) for Sigma. A5, A10 and A20 measured in EXTEM, INTEM and APTEM obtained from ROTEM® Delta and Sigma devices were similar. EXTEM, FIBTEM and APTEM CT values from both devices showed no correlation. Substantial variation was found between FIBTEM assays of the devices. Consequently, results of FIBTEM assays should always be interpreted in the context of device-specific reference values. Correlation with Clauss fibrinogen was better in the ROTEM® Sigma device.  相似文献   
993.
994.
ABSTRACT

Allergic asthma is a highly prevalent inflammatory disease of the lower airways, clinically characterized by airway hyperreactivity and deterioration of airway function. Immunomodulatory probiotic bacteria are increasingly being explored to prevent asthma development, alone or in combination with other treatments.

In this study, wild-type and recombinant probiotic Lactobacillus rhamnosus GR-1 were tested as preventive treatment of experimental allergic asthma in mice. Recombinant L. rhamnosus GR-1 was designed to produce the major birch pollen allergen Bet v 1, to promote allergen-specific immunomodulation. Administration of wild-type and recombinant L. rhamnosus GR-1 prevented the development of airway hyperreactivity. Recombinant L. rhamnosus GR-1 also prevented elevation of airway total cell counts, lymphocyte counts and lung IL-1β levels, while wild-type L. rhamnosus GR-1 inhibited airway eosinophilia. Of note, a shift in gut microbiome composition was observed after asthma development, which correlated with the severity of airway inflammation and airway hyperreactivity. In the groups that received L. rhamnosus GR-1, this asthma-associated shift in gut microbiome composition was not observed, indicating microbiome-modulating effects of this probiotic.

These data demonstrate that L. rhamnosus GR-1 can prevent airway function deterioration in allergic asthma. Bet v 1 expression by L. rhamnosus GR-1 further contributed to lower airway inflammation, although not solely through the expected reduction in T helper 2-associated responses, suggesting involvement of additional mechanisms. The beneficial effects of L. rhamnosus GR-1 correlate with increased gut microbiome resilience, which in turn is linked to protection of airway function, and thus further adds support to the existence of a gut-lung axis.  相似文献   
995.
In 2002, the National Legionella Outbreak Detection Program was implemented in the Netherlands to detect and eliminate potential sources of organisms that cause Legionnaires’ disease (LD). During 2002–2012, a total of 1,991 patients with LD were reported, and 1,484 source investigations were performed. Of those sources investigated, 24.7% were positive for Legionella spp. For 266 patients with LD, 105 cluster locations were identified. A genotype match was made between a strain detected in 41 patients and a strain from a source location. Despite the systematic approach used by the program, most sources of LD infections during 2002–2012 remained undiscovered. Explorative studies are needed to identify yet undiscovered reservoirs and transmission routes for Legionella bacteria, and improved laboratory techniques are needed to detect Legionella spp. in clinical samples with a high background of microbial flora (such as soil).  相似文献   
996.
997.
998.
Lysozyme-loaded poly(ethylene glycol terephthalate)-poly(butylene terephthalate) (PEGT/PBT) films were prepared using a water-in-oil emulsification solvent evaporation method. Infrared spectroscopic analysis of the dried films indicated the presence of non-covalent lysozyme aggregates in the polymer matrix. The use of methanol to enhance the drying rate of the films increased the relative amount of aggregates. Surprisingly, quantitative in-vitro release of fully active, non-aggregated lysozyme was observed, indicating that lysozyme forms reversible aggregates during encapsulation in PEGT/PBT films.  相似文献   
999.
The views of various disciplines on the role of education in improving the health and survival of young children in developing countries are discussed, as well as the factors and processes explaining this impact of education and the influence which education could have on risk factors especially relevant to acute respiratory infections (ARI) and pneumonia. This is by reviews of the available evidence on the impact of maternal education on mortality and morbidity. Since there are hardly any data dealing with the impact of education on pneumonia mortality, we focus on post/neonatal mortality, assuming that it is a suitable proxy for pneumonia mortality. Evidence is summarized on several processes or mechanisms which could explain why there is such an impact of education on ARI mortality (and morbidity) in children below 5. An attempt is made to quantify the reduction in pneumonia mortality which has occurred during the past 10–15 years as a result of improvement in women's education. This will also give an indication of the magnitude of the potential benefits of education for health and survival in the years ahead. Throughout this report we define maternal education as the regular schooling received by women during their youth. Some may have followed additional adult education classes before they became mothers.  相似文献   
1000.
In this study the focus is on the comparison of fluorometric assays, using Alamar Blue (AB) and Hoechst 33342 coloration, and luminometric assays, using Cyto-Lite and ATP-Lite, for toxicity measurements. With AB, ATP-Lite and Cyto-Lite the energy status of the cell is measured and with Hoechst 33342 the amount of DNA. These assays were carried out with different dosages of several toxic compounds with the following permanent cell lines: human liver (Hep G2), human endometrium (ECC-1), human cervix (HeLa) and Chinese hamster ovary (CHO) cells. In these assays toxicity of 110 compounds was assessed in Hep G2 cells. With 60 of those, toxicity was assessed in Hela, ECC-1 and CHO cells. These compounds were non-narcotic antitussives, nasal decongestants, narcotic analgesics, hypnotics, vasodilators, specific cellular energy blockers, cellular proliferation inhibitors, ion channel blockers, estrogens, antiestrogens, androgens, progestagens and others. The outcome of this study is that all four cell lines were responsive to the same set of 60 drugs with a comparable indication of toxicity. Hep G2 cells appear slightly more sensitive, as compared to the other three cell lines. Evaluation up to dosages of 3.2 x 10(-4) or even 3.2 x 10(-3)M for some of the compounds for these four assays in Hep G2 cells demonstrated toxicity for 45 of the 60 (75%) reference compounds with known toxicity in these assays. With a new set of 50 compounds, among which there were estrogens, androgens, progestagens and antiestrogens, 18 (36%) were identified as toxic up to a concentration of 3.2 x 10(-5)M. In conclusion, many of the 60 tested reference compounds gave similar dose and toxicity effects on these permanent cell lines. Therefore, all these cell lines can be used for toxicity screening with AB, ATP-Lite, Cyto-Lite and Hoechst 33342. However, species specific cell lines may reveal species specific effects, as shown with digoxin.  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