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   727篇
  免费   19篇
  国内免费   6篇
耳鼻咽喉   2篇
儿科学   19篇
妇产科学   6篇
基础医学   34篇
口腔科学   6篇
临床医学   39篇
内科学   127篇
皮肤病学   3篇
神经病学   8篇
特种医学   239篇
外科学   203篇
综合类   31篇
预防医学   11篇
眼科学   1篇
药学   12篇
中国医学   1篇
肿瘤学   10篇
  2020年   2篇
  2019年   3篇
  2017年   3篇
  2016年   2篇
  2015年   7篇
  2014年   10篇
  2013年   11篇
  2012年   10篇
  2011年   13篇
  2010年   16篇
  2009年   14篇
  2008年   14篇
  2007年   15篇
  2006年   23篇
  2005年   34篇
  2004年   17篇
  2003年   33篇
  2002年   32篇
  2001年   25篇
  2000年   40篇
  1999年   35篇
  1998年   39篇
  1997年   36篇
  1996年   22篇
  1995年   31篇
  1994年   27篇
  1993年   19篇
  1992年   25篇
  1991年   15篇
  1990年   18篇
  1989年   22篇
  1988年   16篇
  1987年   14篇
  1986年   14篇
  1985年   24篇
  1984年   6篇
  1983年   10篇
  1982年   2篇
  1981年   6篇
  1980年   5篇
  1979年   5篇
  1978年   8篇
  1977年   8篇
  1976年   8篇
  1975年   3篇
  1974年   2篇
  1972年   2篇
  1971年   1篇
  1970年   1篇
  1967年   1篇
排序方式: 共有752条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
Numerous methods for reading abnormalities of rheumatoid arthritis in hand and wrist radiographs have been proposed over the past several decades. There are many differences among these methods, one of the more striking of which is the variation in the number of joints that are scored. In this study, we tested the number of joints that need to be read in order to represent abnormalities accurately and reproducibly, using the scores of multiple observers. Thirteen rheumatologists and radiologists each read a set of 41 hand and wrist films from patients with rheumatoid arthritis. Ten of 13 readers scored 27 joints in each hand and wrist; the other 3 readers scored fewer areas. Fourteen combinations of joints were selected based on the frequency of involvement and the technical adequacy of routine films in assessing a given area. After testing these 14 different combinations, 1 scheme, which included 17 areas read for erosions and 18 areas read for joint space narrowing, was tested further. The correlation coefficients for 10 intraobserver scores derived from this modified scheme compared with the original scores were between 0.981 and 0.997. Seventy-one of 78 interobserver comparisons were better using the new scheme than using the original scheme. These data indicate that the simplified scheme, using a combination of 17 joints to score erosions and 18 to score joint space narrowing, more accurately reflects the extent of abnormalities perceived by a panel of experts than does the original scheme. This abbreviated number of joints shortens the amount of time required to read a set of films and simplifies the scoring of films, since a number of areas that are difficult to read are eliminated from radiographic assessment.  相似文献   
5.
A 31-year-old white female developed severe bilateral hip pain during the third trimester of pregnancy that persisted after parturition. Laboratory abnormalities (elevated alkaline phosphatase and erythrocyte sedimentation rate) and radiographic changes (faint demineralization of the femur in the more symptomatic hip on plain films with evidence of bone marrow oedema and small joint effusions bilaterally on MRI) in the absence of other causes of focal osteoporosis were consistent with the diagnosis of transient osteoporosis of the hip in pregnancy. Although loss of bone mineral density (BMD) characterizes this syndrome, serial BMD measurements in symptomatic transient osteoporosis of the hip in pregnancy have not previously been reported. In the case reported here, serial bone density measurements were obtained over a 4-year period following the onset of symptoms. BMD in both femoral necks, which Initially was approximately 20% lower than the average for age matched controls, increased markedly during the first year, plateaued during the following year, and then rapidly increased again following cessation of lactation. Unexpectedly, BMD in the lumbar spine, an asymptomatic site, was also markedly decreased at the time of presentation (31% lower than the mean of age-matched controls). Recovery of spinal density did not occur during the first year. However, spinal BMD did begin to increase during the second year and continued to rise after the cessation of lactation. In contrast to the marked reduction in bone density at these sites of trabecular bone, cortical bone density in the forearm was normal. Possible aetiologies of pregnancy associated osteoporosis are discussed.  相似文献   
6.
Hemoglobinopathies have a protective role in malaria that appears to be related to alterations in red blood cell (RBC) properties. Thalassemic RBCs infected with Plasmodium falciparum showed greatly reduced cytoadherence and rosetting properties as well as impaired growth and multiplication. A significant decrease in the levels of falciparum antigens associated with the membrane of infected beta-thalassemic RBCs was observed at trophozoite/schizont stage, but not young ring stage. This reduction was shown when a cytoadherence inhibitory monoclonal antibody, but not a noninhibitory pooled immune serum, was used. These observations suggest that protection against malaria in thalassemia is caused by both reduced parasitemias and altered adherence properties of the infected thalassemic RBCs that promote enhanced clearance of the parasite from the circulation.  相似文献   
7.
Radiologic assessment of progressive joint destruction in rheumatoid arthritis is generally considered to be the ultimate standard for evaluation of treatment. We compared alternative radiologic techniques by performing a randomized, controlled trial in which hand films of rheumatoid arthritis patients were read by several skilled observes. The number of joints evaluated (34 versus 18) was found to make relatively little difference, but the number of readers and their experience level was critical. Films should be read in pairs. Joint space narrowing and erosion scores were shown to contribute independent information. Use of recommended techniques can reduce the number of patients required and, thus, can reduce the cost of a clinical trial by more than half and can substantially increase the sensitivity and efficiency of a trial. Therefore, critical selection of the method of assessing study endpoint is of great importance.  相似文献   
8.
A bleeding disorder with absent collagen-induced platelet aggregation and adhesion has been described in a patient whose platelets failed to express surface glycoprotein Ia. We studied the interaction of her platelets with subendothelium in an annular perfusion chamber and the interaction with purified human collagen type III in a rectangular perfusion system under flow conditions. Platelet adherence was almost completely absent both at low and high shear rates. The few platelets which adhered remained in the contact stage without subsequent spreading and aggregate formation. Addition of a monoclonal antibody, which was directed against the von Willebrand moiety of FVIII-VWF, to the blood, completely abolished platelet adherence at high shear rates and had a partial effect at low shear rates. These data indicate that von Willebrand factor plays a role in the initial attachment (contact stage) of platelets to subendothelium. We conclude that the bleeding disorder and excessively prolonged bleeding time in our patient are caused by a new specific defect of the platelet-vessel wall interaction.  相似文献   
9.
The committee was charged with determining whether healing of erosions in rheumatoid arthritis (RA) occurs. Two exercises were performed: The first asked the committee members, as a panel of experts, to express agreement or disagreement with the presence of improvement and features of bone reaction to injury in images submitted by members as examples of healing. The second presented panel members with 28 pairs of serial images, 14 chosen to illustrate progression and 14 chosen to illustrate repair. Agreement was tested on 8 items: global judgment on which image in the pair was better, relative size of the erosion in the 2 images, judgment on which image was first, presence and extent of sclerosis, cortication, filling-in, remodeling, and reconstituting normal structure. Our results showed good agreement, among the 15 respondents, on global assessment of which image was better and which image showed the smaller erosion. Correct assignment of sequence was only slightly better than expected by chance (in 65% of the cases). Agreement was poor regarding the presence of morphologic features of bone repair. A majority of a panel of experts agreed on which 2nd images in a set of paired, serial images represented improvement and which showed progression based on global assessment of which was better and on size of erosion. Features of bone repair were not distinctive and did not enable the panel to deduce the correct sequence of the serial images. This study provides evidence that repair of bone damage in RA does occur, resulting in some degree of improvement, which was recognized by a majority of a panel of experts.  相似文献   
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