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   1765622篇
  免费   136030篇
  国内免费   6710篇
耳鼻咽喉   22425篇
儿科学   56897篇
妇产科学   46779篇
基础医学   259152篇
口腔科学   46776篇
临床医学   160667篇
内科学   351810篇
皮肤病学   41587篇
神经病学   137990篇
特种医学   71412篇
外国民族医学   323篇
外科学   273276篇
综合类   37813篇
现状与发展   4篇
一般理论   516篇
预防医学   138978篇
眼科学   38169篇
药学   127539篇
  6篇
中国医学   3157篇
肿瘤学   93086篇
  2018年   17984篇
  2016年   16652篇
  2015年   18556篇
  2014年   25626篇
  2013年   38272篇
  2012年   48942篇
  2011年   53122篇
  2010年   32492篇
  2009年   31071篇
  2008年   49247篇
  2007年   53112篇
  2006年   53611篇
  2005年   51791篇
  2004年   49957篇
  2003年   48433篇
  2002年   46192篇
  2001年   82883篇
  2000年   85110篇
  1999年   70979篇
  1998年   20886篇
  1997年   18499篇
  1996年   19442篇
  1995年   19384篇
  1994年   17967篇
  1993年   16968篇
  1992年   58154篇
  1991年   58305篇
  1990年   56523篇
  1989年   54331篇
  1988年   50206篇
  1987年   49590篇
  1986年   46510篇
  1985年   44871篇
  1984年   33992篇
  1983年   28676篇
  1982年   17248篇
  1981年   15522篇
  1980年   14701篇
  1979年   30909篇
  1978年   22346篇
  1977年   18627篇
  1976年   17795篇
  1975年   19336篇
  1974年   22466篇
  1973年   21510篇
  1972年   19866篇
  1971年   18471篇
  1970年   17052篇
  1969年   15936篇
  1968年   14909篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
31.
32.
Transplant ureteric stent insertion reduces the incidence of MUCs, but it is not known whether routine PSRGU is needed to detect unmasked MUCs. This study evaluated whether routine PSRGU in the pRTR is a useful tool to identify MUCs before they become clinically apparent. A retrospective analysis was undertaken of the clinical outcomes following elective stent removal from pediatric kidney‐only transplant recipients at two London centers between 2012 and 2016. Our policy was to perform PSRGU either routinely or urgently if there were concerning symptoms or biochemical evidence of renal allograft dysfunction. Elective stent removal was performed in 86% (97 of 113 pRTR), and 75 (77%) of whom had routine PSRGU at a median (IQR) of 6 (2‐8) days after stent removal. There were changes to management in 3 (4%) of pRTR with PSRGU identifying no MUC. Nineteen patients (25%) had urgent PSRGU, most commonly due to renal allograft dysfunction, at a median (IQR) of 5.5 (2.7‐12.3) days after stent removal. Of these, two pRTR required ureteric intervention. For our current practice of removing transplant stents at 4‐6 weeks post‐transplantation, our study has found no evidence to support routine PSRGU after elective stent removal.  相似文献   
33.
Monitoring variations in the functioning of the autonomic nervous system may help personalize training of runners and provide more pronounced physiological adaptations and performance improvements. We systematically reviewed the scientific literature comparing physiological adaptations and/or improvements in performance following training based on responses of the autonomic nervous system (ie, changes in heart rate variability) and predefined training. PubMed, SPORTDiscus, and Web of Science were searched systematically in July 2019. Keywords related to endurance, running, autonomic nervous system, and training. Studies were included if they (a) involved interventions consisting predominantly of running training; (b) lasted at least 3 weeks; (c) reported pre- and post-intervention assessment of running performance and/or physiological parameters; (d) included an experimental group performing training adjusted continuously on the basis of alterations in HRV and a control group; and (e) involved healthy runners. Five studies involving six interventions and 166 participants fulfilled our inclusion criteria. Four HRV-based interventions reduced the amount of moderate- and/or high-intensity training significantly. In five interventions, improvements in performance parameters (3000 m, 5000 m, Loadmax, Tlim) were more pronounced following HRV-based training. Peak oxygen uptake () and submaximal running parameters (eg, LT1, LT2) improved following both HRV-based and predefined training, with no clear difference in the extent of improvement in . Submaximal running parameters tended to improve more following HRV-based training. Research findings to date have been limited and inconsistent. Both HRV-based and predefined training improve running performance and certain submaximal physiological adaptations, with effects of the former training tending to be greater.  相似文献   
34.
Pharmaceutical Chemistry Journal - An HPLC-MS method for simultaneous quantitative determination of a novel gestagenic pharmaceutical and two of its metabolites in rat and rabbit blood sera was...  相似文献   
35.
Purpose: To use polymerase chain reaction (PCR) and Goldmann-Witmer coefficient (GWC) calculation to diagnose infectious uveitis.

Methods: Prospective cross-sectional study.

Results: Twenty-seven of 106 patients had positive PCR and/or GWC results on aqueous humor (AH) sampling and 15 of 27 (55.6%) were HIV-positive. Patients with non-anterior uveitis (NAU) were more likely to be HIV+ (p = 0.005). More than 1 possible pathogen was identified in 9 of 27 patients of whom 7 were HIV+. The final clinical diagnosis was discordant with AH findings in 9 of 27 cases. A positive EBV PCR result was associated with a discordant diagnosis (p = 0.001). All cases of herpetic anterior uveitis (42.9% HIV+) tested PCR-/GWC+ while all cases of herpetic NAU tested PCR+/GWC- (83.3% HIV+). All rubella virus cases were PCR+/GWC+.

Conclusion: PCR is useful to diagnose herpetic NAU in HIV+ patients while GWC is useful to diagnose herpetic anterior uveitis.  相似文献   

36.
37.
38.
Bulletin of Experimental Biology and Medicine - Ammonium, an end-product of catabolism, in low doses can promote adaptation of metabolic pathways in erythrocytes under conditions of extreme...  相似文献   
39.
There is evidence that caesarean section delivery can impact on neonatal weight loss and weight gain patterns in the first 5 days of life. We conducted an integrative systematic review to examine the association of mode of delivery on early neonatal weight loss. Pubmed, Cumulative Index to Nursing and Allied Health Literature, Web of Science, Excerpta Medica dataBASE, and Medical Literature Analysis and Retrieval System Online were searched for relevant papers published before June 2019. Reference lists from the relevant papers were then backwards and forwards searched. As neonatal weight loss was reported in different formats, a meta‐analysis could not be carried out. Most studies did not distinguish between elective and emergency caesarean sections or instrumental and nonassisted vaginal deliveries. Seven papers were included. All papers except one found that caesarean section was associated with higher weight loss in the early days of life. Two papers presented data from studies on babies followed up to 1 month. One study found that on day 25, babies born by caesarean section had significantly higher weight gain than those born vaginally, while another found that by day 28, babies born vaginally gained more weight per day (11.9 g/kg/day) than those born by caesarean section (10.9 g/kg/day; p = .02). Overall, infants born by caesarean section lost more weight than those born vaginally, but due to the small number of studies included, more are needed to look at this difference and why it may occur. This discrepancy in weight between the two groups may be corrected over time, but future studies will need larger sample sizes and longer follow‐up periods to examine this.  相似文献   
40.
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