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   247258篇
  免费   11906篇
  国内免费   452篇
耳鼻咽喉   3183篇
儿科学   7554篇
妇产科学   4912篇
基础医学   35442篇
口腔科学   5961篇
临床医学   19670篇
内科学   54331篇
皮肤病学   6440篇
神经病学   22249篇
特种医学   7785篇
外国民族医学   101篇
外科学   31198篇
综合类   1024篇
一般理论   65篇
预防医学   21955篇
眼科学   4874篇
药学   17245篇
中国医学   723篇
肿瘤学   14904篇
  2023年   1382篇
  2022年   1067篇
  2021年   3915篇
  2020年   2306篇
  2019年   4210篇
  2018年   7920篇
  2017年   5279篇
  2016年   5375篇
  2015年   6091篇
  2014年   6375篇
  2013年   10033篇
  2012年   17180篇
  2011年   17032篇
  2010年   8636篇
  2009年   6446篇
  2008年   14639篇
  2007年   15498篇
  2006年   14327篇
  2005年   14080篇
  2004年   13167篇
  2003年   12026篇
  2002年   11315篇
  2001年   6236篇
  2000年   6323篇
  1999年   5609篇
  1998年   941篇
  1997年   788篇
  1996年   732篇
  1992年   3217篇
  1991年   2889篇
  1990年   2746篇
  1989年   2518篇
  1988年   2379篇
  1987年   2206篇
  1986年   2102篇
  1985年   1900篇
  1984年   1426篇
  1983年   1208篇
  1982年   701篇
  1979年   1222篇
  1978年   865篇
  1977年   809篇
  1975年   808篇
  1974年   993篇
  1973年   1007篇
  1972年   942篇
  1971年   925篇
  1970年   870篇
  1969年   910篇
  1968年   788篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
A premature male infant, birth-weight 1460 g, was treated successfully for a Candida albicans septicemia with orally administered fluconazole for 20 days. Dosage was 5 mg/kg/day. No side effects were seen. Fluconazole may present a major progress in treatment of invasive C. albicans infections in neonatology.  相似文献   
102.
Immunoreactivities of two monoclonal antibodies (MAbs) that recognize cone photopigments were tested in the retinas of congenitally blind retinal degenerate (rd) chicks and compared to normally sighted carrier chicks, heterozygous for the mutation. MAb OS-2 had been previously determined to label rod and most cone outer segment membranes in normal chick retinas and is believed to bind to an epitope that is common to several photopigments in chickens. MAb COS-1 labels specifically middle-to-long-wavelength-sensitive cone photopigments in a number of vertebrate species. In rd chicks MAb OS-2 labeled the same number of rod outer segments at the same densities as carrier chicks. However, cone outer segments were less frequently and significantly less heavily labeled with this MAb at all ages tested (1 day, 1 week and 2 weeks post hatching). MAb COS-1 labeled the same number of cone outer segments in both rd and carrier retinas at 1 day of age, however, those outer segments that were labeled in rd specimens had significantly fewer gold particles on them. At both 1 week and 2 weeks of age, rd chick retinas had a significant reduction in numbers of cone outer segments labeled by COS-1. These findings support the hypothesis that the cone photopigment protein is abnormal in the rd chick model of hereditary blindness and retinal degeneration.  相似文献   
103.
104.
105.
Computer simulations of bone remodeling in response to mechanical stresses can be used to understand normal growth and development of the skeleton or to predict the remodeling of bone in response to prosthetic devices. Using a previously derived bone maintenance theory, a technique for computing bone density distributions was applied to the proximal femur and tibia using two-dimensional, multiple-loading finite element models. The models initially represented solid, homogeneous structures. Using an iterative bone remodeling technique that relates bone apparent density to loading history, the internal distributions of apparent density and elastic modulus for the normal bones were predicted. The finite element models were then modified to represent bones in which porous-coated femoral surface replacements and tibial tray components had been implanted. The same iterative remodeling method was then applied to predict the distribution of bone around these components. The predicted bone density distributions for the natural femur and tibia agree with previously documented normal bone morphology. The predicted bone density distributions around various implanted prostheses were characteristic of the component under investigation and were consistent with clinical and experimental findings of other investigators. In the femoral head, stress shielding occurred underneath the metal surface replacement cup, resulting in lower densities in the femoral head. The addition of a central femoral cup fixation peg caused bone hypertrophy around the peg. In the tibia, the stress concentrations around the pegs also resulted in denser bone, with a concomitant decrease in bone density at more peripheral locations underneath the prosthetic tray. This remodeling technique has the potential to be an important tool in predicting the possible remodeling consequences of new implant design features.  相似文献   
106.
107.
Perimetry suffers from considerable variability of results. A new technique for estimating individual criterion levels in normal subjects exposes the important role of psychological variables. The analysis depends on features peculiar to acuity perimetry. It can be accommodated in the regular examination. The results can be used to compensate for practice effects in serial examinations and to tighten the range of normal limits. The reduction in variation between normal subjects amounted to 57 per cent.  相似文献   
108.
One of the causes of implant failures in cemented implant-retained prostheses is the fracture of abutment screw or UCLA abutment. This article reports a case of simultaneous fracture of two UCLA abutments screws occurring in an implant-supported prosthesis placed in the mandibular molar region. The fractured structures were examined under scanning electron microscopy to investigate the probable causes of the failure, which were not related to failures on materials or fabrication of the screws, but rather were due to shear forces. The misfit in cemented prostheses may be the most likely cause of shear force generation.  相似文献   
109.
Ammonium excretion into urine is a major process essential to the regulation of acid-base homeostasis. We have shown that Rh-type proteins, including renal RhCG, belong to the Mep/Amt family of ammonium transporters and promote bi-directional ammonium transport upon heterologous expression in yeast. To study the physiological role of RhCG and to test a potential function in ammonium excretion, we have generated mice bearing an invalidation of the corresponding gene.  相似文献   
110.
A technique for transperineal high-dose-rate (HDR) prostate brachytherapy and needle biopsy in a standard 1.5 T MRI scanner is demonstrated. In each of eight procedures (in four patients with intermediate to high risk localized prostate cancer), four MRI-guided transperineal prostate biopsies were obtained followed by placement of 14-15 hollow transperineal catheters for HDR brachytherapy. Mean needle-placement accuracy was 2.1 mm, 95% of needle-placement errors were less than 4.0 mm, and the maximum needle-placement error was 4.4 mm. In addition to guiding the placement of biopsy needles and brachytherapy catheters, MR images were also used for brachytherapy treatment planning and optimization. Because 1.5 T MR images are directly acquired during the interventional procedure, dependence on deformable registration is reduced and online image quality is maximized.  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