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   3185篇
  免费   145篇
  国内免费   20篇
耳鼻咽喉   26篇
儿科学   144篇
妇产科学   61篇
基础医学   423篇
口腔科学   71篇
临床医学   338篇
内科学   635篇
皮肤病学   24篇
神经病学   297篇
特种医学   143篇
外国民族医学   1篇
外科学   544篇
综合类   17篇
预防医学   151篇
眼科学   67篇
药学   214篇
中国医学   5篇
肿瘤学   189篇
  2023年   17篇
  2021年   43篇
  2020年   23篇
  2019年   35篇
  2018年   47篇
  2017年   26篇
  2016年   63篇
  2015年   65篇
  2014年   72篇
  2013年   115篇
  2012年   148篇
  2011年   200篇
  2010年   105篇
  2009年   99篇
  2008年   186篇
  2007年   157篇
  2006年   151篇
  2005年   150篇
  2004年   114篇
  2003年   124篇
  2002年   127篇
  2001年   112篇
  2000年   108篇
  1999年   95篇
  1998年   38篇
  1997年   33篇
  1996年   23篇
  1995年   27篇
  1994年   28篇
  1993年   18篇
  1992年   63篇
  1991年   46篇
  1990年   52篇
  1989年   37篇
  1988年   43篇
  1987年   39篇
  1986年   33篇
  1985年   40篇
  1984年   39篇
  1983年   22篇
  1981年   16篇
  1979年   30篇
  1978年   16篇
  1973年   18篇
  1972年   20篇
  1971年   18篇
  1970年   17篇
  1969年   17篇
  1967年   16篇
  1966年   17篇
排序方式: 共有3350条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
To evaluate the feasibility of implementing a cardiac assist system in a nonuniversity hospital we analyzed 18 consecutive patients treated with venoarterial membrane oxygenation. The system was used electively in 5/18 (27.8%) patients during high‐risk interventions. Thirteen patients (72.2%) were treated in emergency situations. The extracorporal system could be initiated successfully in all patients. Periprocedural complications were hemolysis in 3/18 (16.7%), disseminated intravascular coagulation in 2/18 (11.1%), cerebral ischemia in 1/18 (5.6%), and local infection in 2/18 (11.1%) patients. None of these led to a discontinuation of the therapy. All electively treated patients were successfully weaned from the extracorporeal system. In 9/13 (69.2%) emergency patients the system was removed successfully. The 60‐day survival rate of the emergency patients was 53.8% (7/13). Our experience confirms that an innovative extracorporeal circulatory support system can be implemented in a nonuniversity hospital at a tolerable risk and a low complication and high procedural success rate.  相似文献   
6.
Zusammenfassung An 185 Patienten der kieferorthopädischen Abteilung der Stomatologischen Klinik der Friedrich-Schiller-Universität Jena wurde die Mitarbeit der Patienten bei der Behandlung in Beziehung zu verschiedenen Faktoren untersucht und die Ergebnisse statistisch bearbeitet.  相似文献   
7.
168 (21.7%) of 776 pupils from primary classes in Jena had normal tooth position and occlusion. 94 of them were selected for a longitudinal study. Up to now, they have been examined at the ages of 7 and 8 years. The evaluation of the results obtained showed differences with regard to age and sex. The data reported and the deviations observed may be considered reference values. They concrete the assessment of the growth and development in the orofacial system, facilitate the recognition of dysgnathias which must be treated and optimize the planning and performance of orthodontic treatment.  相似文献   
8.
This in vitro study evaluated the effect of metal alloys on three-body wear resistance of enamel and dentin, and vice versa. Three-body wear of human enamel, dentin, a soft gold alloy (BiOcclus Inlay), a CoCr alloy (Remanium 2000), a resin cement (Variolink II) and a zinc oxide phosphate cement (Harvard) was investigated using the ACTA-machine. Sample chambers of eight sample wheels were prepared with pure materials or combinations of human tooth substance, alloys and cement, simulating an inlay-like situation. After 100,000 and 200,000 cycles in a millet suspension with a spring force of 20 N, the amount of abraded material was profilometrically measured and evaluated by 3D surface data analysis. After 200,000 cycles, the materials demonstrated a mean loss of 0.41 microm for CoCr, 51 microm for gold, 57 microm for enamel, 164 microm for dentin, 79 microm for Variolink and 369 microm for Harvard. Using ANOVA and the Games-Howell-test, resin cement, enamel and gold were a subset not shown to differ, as was zinc phosphate cement and dentin. CoCr demonstrated the least wear and differed significantly from all materials. Enamel wear was significantly reduced in mixed chambers with CoCr, and gold after 200,000 cycles compared to enamel in pure chambers. In summary, a soft gold alloy can be recommended for inlays when considering three-body abrasion since the wear rate of the "soft" gold alloy corresponded to that of human enamel.  相似文献   
9.
Root substance removal by scaling and root planing.   总被引:1,自引:0,他引:1  
The amount of root substance removed by scaling and root planing is largely unknown. The present study evaluated in vitro the root substance loss caused by a defined number of working strokes at known forces. Forty extracted teeth with loss of connective tissue attachment into the middle third of the roots were washed and embedded in plaster, leaving one entire corono-apical tooth aspect exposed. The teeth were reproducibly repositioned in a bench-vise, where a profilometer repeatedly measured root surface levels at the same location. In a standard area of the roots a total of 40 working strokes were applied. Low forces were used in 30 teeth and high forces in 10 teeth. The forces were recorded using a piezo-electric receiver built into the upper shank of the curet. Root substance loss was measured after 5, 10, 20, and 40 working strokes. The results showed that the mean low force used per working stroke across all 40 strokes was 3.04 Newtons for the low forces, and 8.48 Newtons for the high forces. Mean cumulative loss of root substance across 40 strokes was 148.7 microns at low forces, and 343.3 microns at high forces. The mean force per stroke increased slightly across the 40 strokes, while substance removal per stroke decreased. Substance removal per stroke during strokes 1 to 5 was 6.8 microns using low forces and 20.6 microns using high forces. During strokes 21 to 40 mean removal per stroke was 2.3 microns at low forces, and 5.6 microns at high forces. These results suggest that high forces remove more root substance, and loss per stroke becomes less with increasing numbers of strokes.  相似文献   
10.
To improve integration between implants and biological tissues, this study compared bone sialoprotein (BSP) as a surface-coating material against the major organic and inorganic components of bone, collagen type I and hydroxyapatite (TICER). The expression of osteocalcin, osteonectin and transforming growth factor ss was evaluated using immunohistochemical staining procedures. The distribution patterns of osteoblasts on the surface of pure titanium with a smooth machined surface and a rough surface (TICER) were determined by image processing using confocal laser scanning microscopy. The results compared to uncoated control materials showed that, at all times investigated, the number of cells on the surface of the TICER and pure titanium samples differed significantly (P<0.1), demonstrating the superiority of TICER over pure titanium in this respect. For pure titanium implants, collagen-precoated surfaces were not beneficial for the attachment of bone-derived cells with the exception of day 3 in vitro (P<0.01). BSP-precoated implant surfaces displayed non-significantly higher numbers of settled cells. BSP-precoated implant surfaces were beneficial for osteoinduction as revealed by osteocalcin and osteonectin expression. BSP precoating of the rough TICER implant surface enhanced the osteoinductive effect much more than did collagen precoating. These results contribute to the consideration of at least two distinct pathways of osseointegration.  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