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   1074917篇
  免费   71566篇
  国内免费   1365篇
耳鼻咽喉   15015篇
儿科学   34606篇
妇产科学   28623篇
基础医学   153389篇
口腔科学   29555篇
临床医学   94904篇
内科学   203624篇
皮肤病学   24391篇
神经病学   81436篇
特种医学   42961篇
外国民族医学   201篇
外科学   163089篇
综合类   21702篇
现状与发展   1篇
一般理论   263篇
预防医学   74599篇
眼科学   24535篇
药学   86101篇
  7篇
中国医学   2805篇
肿瘤学   66041篇
  2019年   7755篇
  2018年   11293篇
  2017年   8906篇
  2016年   10094篇
  2015年   11260篇
  2014年   15267篇
  2013年   22197篇
  2012年   30543篇
  2011年   32285篇
  2010年   18949篇
  2009年   17813篇
  2008年   29944篇
  2007年   32064篇
  2006年   32698篇
  2005年   31027篇
  2004年   29720篇
  2003年   28549篇
  2002年   27525篇
  2001年   60019篇
  2000年   61475篇
  1999年   50927篇
  1998年   12443篇
  1997年   10999篇
  1996年   11014篇
  1995年   10320篇
  1994年   9341篇
  1993年   8857篇
  1992年   37788篇
  1991年   36273篇
  1990年   35744篇
  1989年   34285篇
  1988年   30864篇
  1987年   29986篇
  1986年   28214篇
  1985年   26448篇
  1984年   19185篇
  1983年   16113篇
  1982年   8822篇
  1979年   17029篇
  1978年   11404篇
  1977年   10229篇
  1976年   8837篇
  1975年   10068篇
  1974年   11651篇
  1973年   11273篇
  1972年   10754篇
  1971年   10092篇
  1970年   9252篇
  1969年   8938篇
  1968年   7917篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
BACKGROUND: Fractures of the mandible are a common form of facial injury. The aetiological factors associated with mandibular fractures and the trends in these factors over a 10-year period are reported. METHODS: A retrospective survey was carried out of 724 patients presenting with a fracture of the mandible over the 10-year-period 1994-2003. Patients; records were reviewed and analyzed according to age, sex, cause of injury, anatomic site of fracture, treatment and postoperative complications. RESULTS: Over the 10-year-period the rate of mandibular fractures remained constant (mean 40,7%). There were no changes in the age group (mean 33,3 years) or in the higher prevalence in male (male-female-ratio 2,3 : 1). The major causes of fractures were assaults (38,6%) and accidental fall (27,3%). The most common fracture site was the condylar region (47,0%) followed by the angle (29,4%). Most fractures were treated by closed reduction until 2002, thereafter surgical treatment increased noticeable. The complication rate was 8,9% and the most common complications were hardware exposure and infection. CONCLUSION: Fractures of the mandible are a prevalent form of facial injury. Aetiological factors show no significant change over the 10-year-period. Complication-rate is low and will support the tendency towards surgical treatment.  相似文献   
992.
993.
994.
Reduction of transmission of human immunodeficiency virus type 1 (HIV-1) through human milk is needed. Alkyl sulfates such as sodium dodecyl sulfate (SDS) are microbicidal against HIV-1 at low concentrations, have little to no toxicity, and are inexpensive. The authors have reported that treatment of HIV-1-infected human milk with < or = 1% (10 mg/mL) SDS for 10 minutes inactivates cell-free and cell-associated virus. The SDS can be removed with a commercially available resin after treatment without recovery of viral infectivity. In this article, the authors report results of selective biochemical analyses (ie, protein, immunoglobulins, lipids, cells, and electrolytes) of human milk subjected to SDS treatment and removal. The SDS treatment or removal had no significant effects on the milk components studied. Therefore, the use of alkyl sulfate microbicides to treat milk from HIV-1-positive women may be a simple, practical, and nutritionally sound way to prevent or reduce transmission of HIV-1 while still feeding with mother's own milk.  相似文献   
995.
Efficient high-frequency body coil for high-field MRI.   总被引:1,自引:0,他引:1  
The use of body coils is favored for homogeneous excitation, and such coils are often paired with surface coils or arrays for sensitive reception in many MRI applications. While the body coil's physical size and resultant electrical length make this circuit difficult to design for any field strength, recent efforts to build efficient body coils for applications at 3T and above have been especially challenging. To meet this challenge, we developed an efficient new transverse electromagnetic (TEM) body coil and demonstrated its use in human studies at field strengths up to 4 T. Head, body, and breast images were acquired within peak power constraints of <8 kW. Bench studies indicate that these body coils are feasible to 8 T. RF shimming was used to remove a high-field-related cardiac imaging artifact in these preliminary studies. P41RR13230  相似文献   
996.
997.
A common distal radio-ulnar joint (DRUJ) stabilisation procedure uses a tendon graft running from the lip of the radial sigmoid notch to the ulnar fovea and through a bony tunnel to the ulnar shaft, before being wrapped round the distal ulna and sutured to itself. Such graft fixation can be challenging and requires a considerable tendon length. The graft length could be reduced by fixing the graft to the ulna using a bone anchor or interference screw. The aim of this study was to compare the strength of three distal ulna graft fixation methods (tendon wrapping and suturing, bone anchor and interference screw). Four human cadaveric ulnae were used. A tendon strip was run through a tunnel in the distal ulna and secured by: (1) wrapping round the shaft and suturing it to itself, (2) a bone anchor and (3) an interference screw in the bone tunnel. Load to failure was determined using a custom-made apparatus and an Instron machine. Maximum failure load was highest for the bone anchor fixation (99.3 ± 23.7 N) followed by the suturing (96.2 ± 12.1 N), and the interference screw fixation (46.9 ± 5.6 N). There was no significant difference between the tendon suturing and bone anchor methods, but the tendon suturing was statistically significantly higher compared to the interference screw (P = 0.028). In performing anatomical stabilisation of the DRUJ fixation of the tendon graft to the distal ulna with a bone anchor provides the most secure fixation. This may make the stabilisation technique less demanding and require a smaller tendon graft.  相似文献   
998.
999.
1000.
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