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   419308篇
  免费   13663篇
  国内免费   553篇
耳鼻咽喉   4335篇
儿科学   14233篇
妇产科学   8077篇
基础医学   51931篇
口腔科学   7071篇
临床医学   31692篇
内科学   85703篇
皮肤病学   7091篇
神经病学   38243篇
特种医学   16299篇
外国民族医学   109篇
外科学   59882篇
综合类   3293篇
一般理论   66篇
预防医学   39472篇
眼科学   7446篇
药学   26510篇
中国医学   1359篇
肿瘤学   30712篇
  2023年   1329篇
  2022年   1122篇
  2021年   4020篇
  2020年   2387篇
  2019年   4399篇
  2018年   28756篇
  2017年   21619篇
  2016年   23793篇
  2015年   6810篇
  2014年   7150篇
  2013年   10824篇
  2012年   23922篇
  2011年   37301篇
  2010年   26715篇
  2009年   17779篇
  2008年   33418篇
  2007年   36525篇
  2006年   15206篇
  2005年   16727篇
  2004年   16937篇
  2003年   16733篇
  2002年   14169篇
  2001年   6629篇
  2000年   6807篇
  1999年   5921篇
  1998年   1357篇
  1997年   1170篇
  1996年   981篇
  1995年   900篇
  1992年   3358篇
  1991年   3054篇
  1990年   2961篇
  1989年   2652篇
  1988年   2505篇
  1987年   2299篇
  1986年   2186篇
  1985年   1968篇
  1984年   1470篇
  1983年   1261篇
  1979年   1247篇
  1978年   884篇
  1977年   822篇
  1975年   835篇
  1974年   1026篇
  1973年   1019篇
  1972年   958篇
  1971年   941篇
  1970年   898篇
  1969年   941篇
  1968年   826篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
71.

Background

The ZOE-50 (NCT01165177) and ZOE-70 (NCT01165229) phase 3 clinical trials showed that the adjuvanted recombinant zoster vaccine (RZV) was ≥90% efficacious in preventing herpes zoster in adults. Here we present a comprehensive overview of the safety data from these studies.

Methods

Adults aged ≥50 (ZOE-50) and ≥70 (ZOE-70) years were randomly vaccinated with RZV or placebo. Safety analyses were performed on the pooled total vaccinated cohort, consisting of participants receiving at least one dose of RZV or placebo. Solicited and unsolicited adverse events (AEs) were collected for 7 and 30?days after each vaccination, respectively. Serious AEs (SAEs) were collected from the first vaccination until 12?months post-last dose. Fatal AEs, vaccination-related SAEs, and potential immune-mediated diseases (pIMDs) were collected during the entire study period.

Results

Safety was evaluated in 14,645 RZV and 14,660 placebo recipients. More RZV than placebo recipients reported unsolicited AEs (50.5% versus 32.0%); the difference was driven by transient injection site and solicited systemic reactions that were generally seen in the first week post-vaccination. The occurrence of overall SAEs (RZV: 10.1%; Placebo: 10.4%), fatal AEs (RZV: 4.3%; Placebo: 4.6%), and pIMDs (RZV: 1.2%; Placebo: 1.4%) was balanced between groups. The occurrence of possible exacerbations of pIMDs was rare and similar between groups. Overall, except for the expected local and systemic symptoms, the safety results were comparable between the RZV and Placebo groups irrespective of participant age, gender, or race.

Conclusions

No safety concerns arose, supporting the favorable benefit-risk profile of RZV.  相似文献   
72.
73.
74.
Melatonin, the main hormone produced by the pineal gland, is secreted in a circadian manner (24‐hr period), and its oscillation influences several circadian biological rhythms, such as the regulation of clock genes expression (chronobiotic effect) and the modulation of several endocrine functions in peripheral tissues. Assuming that the circadian synchronization of clock genes can play a role in the regulation of energy metabolism and it is influenced by melatonin, our study was designed to assess possible alterations as a consequence of melatonin absence on the circadian expression of clock genes in the epididymal adipose tissue of male Wistar rats and the possible metabolic repercussions to this tissue. Our data show that pinealectomy indeed has impacts on molecular events: it abolishes the daily pattern of the expression of Clock, Per2, and Cry1 clock genes and Pparγ expression, significantly increases the amplitude of daily expression of Rev‐erbα, and affects the pattern of and impairs adipokine production, leading to a decrease in leptin levels. However, regarding some metabolic aspects of adipocyte functions, such as its ability to synthesize triacylglycerols from glucose along 24 hr, was not compromised by pinealectomy, although the daily profile of the lipogenic enzymes expression (ATP‐citrate lyase, malic enzyme, fatty acid synthase, and glucose‐6‐phosphate dehydrogenase) was abolished in pinealectomized animals.  相似文献   
75.
Objective: To assess the quality of images and video clips of fetal central nervous (CNS) structures obtained by ultrasound and transmitted via tele-ultrasound from Brazil to Australia.

Methods: In this cross-sectional study, 15 normal singleton pregnant women between 20 and 26 weeks were selected. Fetal CNS structures were obtained by images and video clips. The exams were transmitted in real-time using a broadband internet and an inexpensive video streaming device. Four blinded examiners evaluated the quality of the exams using the Likert scale. We calculated the mean, standard deviation, mean difference, and p values were obtained from paired t tests.

Results: The quality of the original video clips was slightly better than that observed by the transmitted video clips; mean difference considering all observers = 0.23 points. In 47/60 comparisons (78.3%; 95% CI?=?66.4–86.9%) the quality of the video clips were judged to be the same. In 182/240 still images (75.8%; 95% CI?=?70.0–80.8%) the scores of transmitted image were considered the same as the original.

Conclusion: We demonstrated that long distance tele-ultrasound transmission of fetal CNS structures using an inexpensive video streaming device provided images of subjective good quality.  相似文献   
76.
77.
In May 2017, the Health and Environmental Sciences Institute's Genetic Toxicology Technical Committee hosted a workshop to discuss whether mode of action (MOA) investigation is enhanced through the application of the adverse outcome pathway (AOP) framework. As AOPs are a relatively new approach in genetic toxicology, this report describes how AOPs could be harnessed to advance MOA analysis of genotoxicity pathways using five example case studies. Each of these genetic toxicology AOPs proposed for further development includes the relevant molecular initiating events, key events, and adverse outcomes (AOs), identification and/or further development of the appropriate assays to link an agent to these events, and discussion regarding the biological plausibility of the proposed AOP. A key difference between these proposed genetic toxicology AOPs versus traditional AOPs is that the AO is a genetic toxicology endpoint of potential significance in risk characterization, in contrast to an adverse state of an organism or a population. The first two detailed case studies describe provisional AOPs for aurora kinase inhibition and tubulin binding, leading to the common AO of aneuploidy. The remaining three case studies highlight provisional AOPs that lead to chromosome breakage or mutation via indirect DNA interaction (inhibition of topoisomerase II, production of cellular reactive oxygen species, and inhibition of DNA synthesis). These case studies serve as starting points for genotoxicity AOPs that could ultimately be published and utilized by the broader toxicology community and illustrate the practical considerations and evidence required to formalize such AOPs so that they may be applied to genetic toxicity evaluation schemes. Environ. Mol. Mutagen. 61:114–134, 2020. © 2019 Wiley Periodicals, Inc.  相似文献   
78.
79.
We evaluated RNA stability of Ebola virus in EDTA blood and urine samples collected from infected patients and stored in West Africa’s environmental conditions. In blood, RNA was stable for at least 18 days when initial cycle threshold values were <30, but in urine, RNA degradation occurred more quickly.  相似文献   
80.
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