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   2320篇
  免费   249篇
  国内免费   5篇
耳鼻咽喉   86篇
儿科学   47篇
妇产科学   179篇
基础医学   352篇
口腔科学   28篇
临床医学   312篇
内科学   404篇
皮肤病学   55篇
神经病学   174篇
特种医学   60篇
外科学   231篇
综合类   33篇
现状与发展   1篇
一般理论   2篇
预防医学   293篇
眼科学   23篇
药学   146篇
中国医学   3篇
肿瘤学   145篇
  2023年   25篇
  2022年   26篇
  2021年   54篇
  2020年   43篇
  2019年   69篇
  2018年   66篇
  2017年   64篇
  2016年   56篇
  2015年   56篇
  2014年   68篇
  2013年   122篇
  2012年   142篇
  2011年   163篇
  2010年   61篇
  2009年   57篇
  2008年   115篇
  2007年   128篇
  2006年   97篇
  2005年   133篇
  2004年   115篇
  2003年   85篇
  2002年   110篇
  2001年   69篇
  2000年   66篇
  1999年   38篇
  1998年   18篇
  1997年   11篇
  1994年   22篇
  1993年   14篇
  1992年   34篇
  1991年   24篇
  1990年   27篇
  1989年   19篇
  1988年   21篇
  1987年   23篇
  1986年   19篇
  1985年   18篇
  1984年   32篇
  1983年   16篇
  1982年   16篇
  1981年   12篇
  1980年   10篇
  1979年   11篇
  1978年   19篇
  1975年   19篇
  1974年   11篇
  1973年   24篇
  1972年   23篇
  1969年   12篇
  1968年   15篇
排序方式: 共有2574条查询结果,搜索用时 15 毫秒
1.
2.
3.

Background  

The objective of this study was to examine missed opportunities for participation in a prevention of mother-to-child transmission (PMTCT) programme in three sites in South Africa. A rapid anthropological assessment was used to collect in-depth data from 58 HIV-positive women who were enrolled in a larger cohort study to assess mother-to-child HIV transmission. Semi-structured interviews were conducted with the women in order to gain an understanding of their experiences of antenatal care and to identify missed opportunities for participation in PMTCT.  相似文献   
4.
5.
6.
Gram negative bacteria precipitate reactive arthritis and may be concerned in the pathogenesis of ankylosing spondylitis and other spondyloarthropathies. Susceptibility to many infectious agents is associated with ABO blood group or secretor state, or both. The distribution of the ABO blood group or secretor state, or both, was therefore determined in 87 patients with ankylosing spondylitis and 32 with other forms of spondyloarthropathy. The prevalence of non-secretors was significantly increased in the total patient group (54/114; 47%) and in the subgroup with ankylosing spondylitis (41/84; 49%) compared with local controls (89/334; 27%) (p less than 0.001). Other subgroups of patients showed a similarly increased prevalence of non-secretion (33-47%). The distribution of ABO blood groups did not differ between patients and controls. The association between non-secretor state and ankylosing spondylitis strengthens the hypothesis that ankylosing spondylitis is a form of reactive arthritis. It also suggests several pathogenic mechanisms which may be relevant to the initial hostparasite interaction in ankylosing spondylitis.  相似文献   
7.
The effectiveness of periocular anaesthesia and its complications were examined in 100 successive cataract operations. The patients were divided into 3 groups according to the duration of ocular compression with an Autopressor device after administration of periocular anaesthesia. In the control group, no compression was used (C-O, n = 36 patients). In the other two groups, compression was used for 10 (C-10, n = 32) and for 20 (C-20, n = 32) min. No differences in globe or orbicular akinesia were found between the groups. At 10 min, immobilisation of the globe in different directions was attained in 60.1-84.5% of the patients. Compression for an additional 10 min did not significantly improve the akinesia. In contrast, the hitherto undescribed loss of light perception increased with time: 15 patients at 10 min and 22 at 20 min were unable to see light. Chemosis and haematomas in the upper eyelid occurred more often in C-0 than in the other 2 groups. One day postoperatively the average palpebral aperture was smaller in C-0 than in the other two groups. The frequent postoperative ptosis (74.3% on the 1st day) decreased rapidly, but on postoperative day 7, 9 patients still had ptosis. In only one patient was ptosis still recognizable at 6 weeks postoperatively. No serious complications occurred. This study demonstrates that periocular anaesthesia with ocular compression is a suitable method for cataract surgery.  相似文献   
8.
Usage of antibiotics in southern Europe is less well regulated than in northern countries. The proportion (48%) of meningococci in Spain insensitive to pencillin (MIC greater than or equal to 0.1 mg/l) prompted this investigation of antibiotic sensitivities of isolates from Greek patients with meningitis (31) and carriers (47 school-children and 472 recruits). The agar dilution method was used to determine MIC to penicillin G (PN), sulphamethoxazole (SU), rifampicin (RF), cefaclor (CF) and ciprofloxacin (CP). The proportion of isolates insensitive to PN was 48% for isolates from patients, 19% from school-children and 36.6% from recruits. Resistance to SU (MIC greater than or equal to 16 mg/l) was found in 16% of those from patients, 10.6% from children and 40% from recruits. None of the isolates from patients was resistant to RF (greater than or equal to 1 mg/l) but 6% of those from carriers were. Resistance to CF (greater than or equal to 4 mg/l) was found in 9.2% of patient isolates, 6.4% from children and 23.7% from recruits. All isolates except one were sensitive to CP (MIC range less than 0.0015-0.125 mg/l). Resistances to PN, SU and RF were analysed by serogroup, serotype and subtype of the bacteria. The proportion of resistant isolates showed some variation between different areas of Greece, but it was not statistically significant.  相似文献   
9.
Extracorporeal membrane oxygenation (ECMO) has been used to treat over 2,000 neonates with severe respiratory distress due to a number of different diagnoses. Its application has been expanded into the pediatric population as well. Despite both technical advances and refinement of management techniques, intracranial hemorrhage remains a major cause of both morbidity and mortality during ECMO. We reviewed our ECMO experience with regard to the diagnosis of intracranial bleeding, and gave particular attention to the technicians' written records. Seven of 50 patients had a documented intracranial event during ECMO, and in all 7, the technicians noted increasing difficulty with control of the activated clotting time (ACT), platelet count, or both. This manifested itself as both inability to raise the ACT and/or platelet count, or inability to decrease the ACT, despite discontinuation of heparin. The patients with intracranial hemorrhages had a significantly greater number of changes in the rate of heparin infusion than matched controls. None of the patients with intracranial bleeding had any signs of extracranial hemorrhage, and none manifested any hemodynamic abnormalities. In 4 cases, the regularly scheduled echoencephalogram was obtained earlier in the day, and the patients were subsequently weaned and decannulated. We conclude from this review that instability of previously well-controlled coagulation parameters is an early predictor of an intracranial event. However, the impact of earlier diagnosis on outcome is less clear from this small number of patients.  相似文献   
10.
We introduce an image processing method which reduces white noise and random artifacts in sets of high resolution, time resolved images. At each pixel, the processing consists of: (1) the isolation of a time intensity curve (TIC), (2) Fourier transformation of each TIC, (3) application of a threshold to remove low intensity coefficients, (4) inverse transformation to generate noise reduced TICS which are recombined to form images with improved signal-to-noise ratio (SNR). Noise filtering by Fourier thresholding is demonstrated on a set of cardiac images, resulting in a reduction of the noise energy by approximately 90%.  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