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   8985篇
  免费   545篇
  国内免费   38篇
耳鼻咽喉   138篇
儿科学   171篇
妇产科学   150篇
基础医学   1336篇
口腔科学   1160篇
临床医学   645篇
内科学   1761篇
皮肤病学   340篇
神经病学   789篇
特种医学   159篇
外科学   893篇
综合类   33篇
一般理论   3篇
预防医学   955篇
眼科学   144篇
药学   564篇
中国医学   83篇
肿瘤学   244篇
  2023年   78篇
  2022年   94篇
  2021年   286篇
  2020年   261篇
  2019年   324篇
  2018年   353篇
  2017年   258篇
  2016年   238篇
  2015年   357篇
  2014年   446篇
  2013年   530篇
  2012年   800篇
  2011年   799篇
  2010年   434篇
  2009年   337篇
  2008年   535篇
  2007年   497篇
  2006年   477篇
  2005年   406篇
  2004年   315篇
  2003年   276篇
  2002年   255篇
  2001年   164篇
  2000年   131篇
  1999年   124篇
  1998年   52篇
  1997年   38篇
  1996年   31篇
  1995年   29篇
  1994年   33篇
  1993年   30篇
  1992年   55篇
  1991年   49篇
  1990年   41篇
  1989年   38篇
  1988年   31篇
  1987年   32篇
  1986年   19篇
  1985年   27篇
  1984年   30篇
  1983年   17篇
  1982年   16篇
  1980年   20篇
  1975年   20篇
  1973年   19篇
  1972年   12篇
  1970年   13篇
  1968年   12篇
  1967年   12篇
  1966年   14篇
排序方式: 共有9568条查询结果,搜索用时 15 毫秒
1.
Clinical Oral Investigations - To examine the relationship between the ICCMS? (International Caries Classification and Managing System) features of root caries lesions and the underlying...  相似文献   
2.
3.
4.
Sport Sciences for Health - This study aimed to review the existing literature concerning the psychological variables of CrossFit participants. This review followed the PRISMA guidelines and was...  相似文献   
5.
Objectives:To evaluate, in an in vitro study, the quantity of artefacts generated by two different restorative materials, and to determine the diagnostic accuracy of cone beam CT (CBCT) scans and periapical radiographs in identifying gaps in prosthetic crowns.Methods:A total of 30 teeth restored with metal-ceramic (n = 15) and all-ceramic (n = 15) crowns, properly adapted and with 0.30- and 0.50 mm gaps, underwent CBCT exams (with voxel sizes of 0.25 and 0.30 mm) and periapical radiographs. The artefacts generated by two different crowns were quantified and compared by the Mann–Whitney test. In addition, five examiners evaluated the presence or absence of gaps in periapical radiographs and CBCT images. The accuracy of tests was determined by the area under the receiver operatring characteristic curve and these values were compared by using the Kruskal–Wallis test.Results:There was no significant difference in artefact values between the different restorative materials and the different resolutions of CBCT images. Regarding the accuracy of the tests evaluated, periapical radiography and CBCT with voxel size 0.25 mm showed the best performance for smaller gaps (0.30 mm). For larger gaps (0.50 mm), all exams tested showed the same performance.Conclusions:Periapical radiography was still the most cost-beneficial method for the diagnosis of maladaptation in dental restorations. CBCT exams did not improve accuracy in detecting gaps in prosthetic crowns.  相似文献   
6.
The objective of this study was to investigate the impact of male age, semen quality and days of ejaculatory abstinence on embryo morphokinetics. A total of 1,220 zygotes obtained from 139 couples in a private in vitro fertilisation centre were analysed. The timing of specific events from the point of insemination, such as timings to pronuclei appearance and fading, to two, three, four, five, six, seven and eight cells and to blastulation were recorded. Multivariate linear regression analysis was used to evaluate the influence of paternal factors on embryo morphokinetic events. Paternal age was positively correlated with delayed cell cleavage and blastulation, and negatively associated with implantation rate, and clinical pregnancy and live–birth chances. The ejaculatory abstinence was inversely correlated with the implantation rate. Inverse relationships were observed between semen parameters (sperm count, progressive sperm motility, total motile sperm count and morphology) and the timing of specific events during embryo development. Sperm morphology was also positively associated with implantation rate and pregnancy and live–birth chances. Increased paternal age and ejaculatory abstinence, and poor semen quality correlate with delayed cell cleavage and blastulation and negatively impact intracytoplasmic sperm injection outcomes.  相似文献   
7.
Neurosurgical Review - There is a lack of class I evidence concerning the impact of surgery in the treatment of diffuse low-grade glioma; the early maximal resection with preservation of eloquent...  相似文献   
8.
Statement of problemRemovable partial dentures (RPDs) are traditionally made by casting, a complex, error-prone, and time-consuming process. Computer-aided design and computer-aided manufacturing (CAD-CAM) RPD systems may simplify the clinical steps and minimize errors; however, the accuracy of CAD-CAM RPD systems is unclear.PurposeThe purpose of this systematic review was to determine whether CAD-CAM systems are accurate for the manufacturing of RPD frameworks.Material and methodsA literature search was conducted through Medline-PubMed, Scopus, Lilacs, Web of Science, and Cochrane Library databases using specific keywords for articles published up to November 2019. Three reviewers obtained data and compared the results. All studies evaluated the framework accuracy or fit of prostheses fabricated with conventional and digital techniques.ResultsA total of 7 articles, 2 clinical studies, and 5 in vitro studies that complied with the inclusion criteria were evaluated. One in vitro study compared indirect (extraoral) and direct (intraoral) scanning for partially edentulous ridges and shows that digital scans were better than conventional impressions in terms of trueness. In the other studies included, although the frameworks analyzed had clinically acceptable discrepancies (<311 μm), the material influenced the fit. Polyetheretherketone (PEEK) showed better fit than traditional metal cast RPDs. Co-Cr alloy RPDs produced by rapid prototyping exhibited the highest discrepancies when produced by sintering laser melting.ConclusionsThe results show that the digital technique for RPD frameworks is accurate. In the studies included, the analyzed frameworks had clinically acceptable gaps, but the results were heterogeneous among studies because the articles used different measurement methods with small sample sizes. Few studies discussed the long-term clinical performance. The digital technique for RPD frameworks was accurate because the misfits and mismatches found in in vitro and clinical studies were within the acceptable clinical limit for RPDs.  相似文献   
9.
10.
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