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   1131214篇
  免费   75634篇
  国内免费   1507篇
耳鼻咽喉   15758篇
儿科学   36110篇
妇产科学   30030篇
基础医学   162608篇
口腔科学   31092篇
临床医学   100260篇
内科学   214825篇
皮肤病学   25270篇
神经病学   86803篇
特种医学   45293篇
外国民族医学   246篇
外科学   170288篇
综合类   22174篇
现状与发展   1篇
一般理论   342篇
预防医学   79086篇
眼科学   25637篇
药学   90179篇
  7篇
中国医学   2959篇
肿瘤学   69387篇
  2021年   8480篇
  2019年   8593篇
  2018年   12275篇
  2017年   9584篇
  2016年   10919篇
  2015年   12218篇
  2014年   16475篇
  2013年   24296篇
  2012年   33186篇
  2011年   35050篇
  2010年   20939篇
  2009年   19475篇
  2008年   32446篇
  2007年   34676篇
  2006年   35322篇
  2005年   33511篇
  2004年   32248篇
  2003年   30844篇
  2002年   29910篇
  2001年   61748篇
  2000年   63246篇
  1999年   52553篇
  1998年   13232篇
  1997年   11639篇
  1996年   11583篇
  1995年   10925篇
  1994年   9836篇
  1993年   9405篇
  1992年   39015篇
  1991年   37472篇
  1990年   36896篇
  1989年   35450篇
  1988年   31838篇
  1987年   30961篇
  1986年   29143篇
  1985年   27316篇
  1984年   19805篇
  1983年   16684篇
  1982年   9241篇
  1979年   17604篇
  1978年   11731篇
  1977年   10555篇
  1976年   9110篇
  1975年   10402篇
  1974年   12031篇
  1973年   11586篇
  1972年   11058篇
  1971年   10362篇
  1970年   9483篇
  1969年   9147篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
Restriction maps of the rDNA cistron of twelve species of mosquitoes in six genera of the subfamily Culicinae were constructed using eight 6 bp recognition restriction enzymes. Anopheles albimanus was used as an outgroup. The size of the rDNA cistron ranged from 8.5 kb in Aedes katherinensis to 12.9 kb in Ae. polynesiensis. A total of twenty-six sites were scored; eighteen were polymorphic among ingroup taxa. The proportion of polymorphic nucleotide sites (Pnuc) was 0.059 and the heterozygosity per nucleotide site (Hnuc) was 0.028. Wagner and Fitch Parsimony, Dollo Parsimony and Nei-Li distance/neighbour-joining methods were used to construct phylogenetic trees. The rDNA RFLP dataset did not provide a well-supported phylogeny among culicine taxa. The RFLP phylogenies are incongruent with the morphology character based and molecular phylogenies and derived relationships did not correspond with current taxonomic classifications. The lack of resolution was due to homoplasy arising from frequent independent loss or gain of restriction sites among unrelated taxa.  相似文献   
982.
983.
984.
A new technique of forehead rhytidectomy is presented that combines the best features of the coronal incision with those of the anterior hairline incision. The plane of dissection is formed by an anterior subcutaneous plane dissecting a lateral subgaleal plane. This approach is particularly valuable in patients with high foreheads, severe static wrinkling, and asymmetrical eyebrows.Presented in part at the Annual Meeting of the American Society of Aesthetic Plastic Surgeons, Boston, MA, 1984  相似文献   
985.
The modified dorsal lithotomy position is excellent for radical pelvic operations. Use of modified Krauss arm supports as stirrups, along with pneumatic devices that intermittently compress the legs, significantly reduces postoperative morbidity in patients who undergo operations in this position.  相似文献   
986.
Controversy persists regarding whether the efficacy of closed instrumental mitral commissurotomy compares well enough with that of open commissurotomy to warrant its continued use. The purpose of this study was to compare the results of operation as determined by catheterization studies in 63 patients with pure, severe, and noncalcified mitral stenosis. The patients were randomly assigned to one of two groups: thirty-two patients were operated on by the closed technique (group I) and 31 by the open technique (group II). All patients underwent left-sided and right-sided catheterization before and 4 months after operation. Preoperatively the two groups were statistically similar with regard to major clinical data and hemodynamic findings. There were no deaths at operation or systemic embolism in the two groups. The prevalence of surgically induced mitral regurgitation was similar in the two groups (12.4% versus 12.9%). Pulmonary arterial pressure and arteriolar and total pulmonary vascular resistance decreased significantly in the two groups. Pulmonary capillary wedge pressure decreased from 23.3 +/- 8.5 to 15.8 +/- 7 mm Hg in group I (p less than 0.001) and from 23.7 +/- 6 to 14 +/- 5.8 mm Hg in group II (p less than 0.001). Cardiac index increased from 2.86 +/- 0.84 to 3.14 +/- 0.78 L/min/m2 in group I, but this increase did not reach statistical significance. In group II cardiac index increased from 2.89 +/- 0.6 to 3.6 +/- 0.6 L/min/m2 (p less than 0.005). The mean and end-diastolic transmitral pressure gradients decreased significantly in the two groups, but the decrease was statistically greater in the open mitral commissurotomy group (p less than 0.001). Mitral valve area increased from 0.82 +/- 0.18 to 1.4 +/- 0.40 cm2 in group I (p less than 0.01) and from 0.84 +/- 0.15 to 2.14 +/- 0.53 cm2 in group II (p less than 0.001). The mean increase in mitral valve area was 0.61 cm2 in group I and 1.34 cm2 in group II (p less than 0.001). At exercise, in patients with resting pulmonary capillary wedge pressures of 18 mm Hg or less, cardiac index increased by 36% in group I (23 patients) and 48% in group II (24 patients), because of a smaller mitral valve area in group I (1.61 +/- 0.39 cm2) than in group II (2.45 +/- 0.65 cm2). Thus open commissurotomy improved hemodynamic values to a greater extent than closed commissurotomy at both rest and exercise.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
987.
988.
989.
We compared midazolam 0.2 mg.kg-1 and fentanyl 50 micrograms with thiamylal 4 mg.kg-1 for rapid sequence induction. We could use midazolam safely in patients with bronchial asthma or drug allergy. There was no difference in time from the beginning of induction to intubation between midazolam treated group and thiamylal treated group. Changes in systolic as well as diastolic blood pressure and heart rate during 2 hours from intubation were smaller in midazolam treated group than in thiamylal treated group. In midazolam treated group, no arrhythmias were observed at the time of intubation. We could reduce the amount of anesthetics in midazolam treated group during 2 hours from intubation. From the results mentioned above, we conclude that midazolam is a useful agent for rapid sequence induction.  相似文献   
990.
Hypospadias   总被引:1,自引:0,他引:1  
  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