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   760篇
  免费   52篇
  国内免费   1篇
耳鼻咽喉   1篇
儿科学   17篇
妇产科学   5篇
基础医学   82篇
口腔科学   10篇
临床医学   76篇
内科学   287篇
皮肤病学   6篇
神经病学   33篇
特种医学   9篇
外科学   31篇
综合类   2篇
预防医学   140篇
眼科学   3篇
药学   44篇
肿瘤学   67篇
  2023年   1篇
  2022年   11篇
  2021年   16篇
  2020年   9篇
  2019年   11篇
  2018年   16篇
  2017年   21篇
  2016年   15篇
  2015年   21篇
  2014年   42篇
  2013年   28篇
  2012年   52篇
  2011年   53篇
  2010年   26篇
  2009年   24篇
  2008年   48篇
  2007年   71篇
  2006年   51篇
  2005年   47篇
  2004年   41篇
  2003年   38篇
  2002年   34篇
  2001年   18篇
  2000年   15篇
  1999年   16篇
  1998年   5篇
  1997年   14篇
  1996年   6篇
  1995年   4篇
  1994年   3篇
  1993年   5篇
  1992年   4篇
  1991年   9篇
  1990年   9篇
  1989年   11篇
  1988年   5篇
  1987年   8篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1983年   2篇
排序方式: 共有813条查询结果,搜索用时 15 毫秒
61.

Background  

No study to date has focused on the impact of Greek Orthodox Christian fasting on serum lipoproteins and obesity yet.  相似文献   
62.
63.
The aim of the present study was to assess androgen plasma levels and biogenic amine metabolites in a sex-offender group as well as to investigate the relationship between the biological findings and the impulsive, aggressive, and suicidal profile of the offenders. Fifty-seven males convicted for rape and 25 normal males comprised the study sample. We found that although both testosterone levels and aggression-impulsivity scores were higher in the group of rapists, testosterone levels were not associated with the aggression and impulsivity scores. Nevertheless, aggression-impulsivity scores were clearly associated with luteinizing hormone levels. This association may indicate a hyperactive hypothalamic-pituitary-gonadal axis, possibly the result of a reduced serotonergic activity.  相似文献   
64.
We report a combination of unusual features demonstrating a permanent pacemaker implantation of a single-pass VDD lead by way of an anomalous persistent left superior vena cava in the middle cardiac vein. The ventricular stimulation resembled a right bundle branch block QRS morphology and was successfully synchronized by spontaneous atrial activity. This case illustrates an alternative approach of effective VDD pacing and sensing in patients with such a venous anomaly when other standard implantation sites fail.  相似文献   
65.
Currently, the prediction of improvement of left ventricular (LV) ejection fraction (EF) after revascularization in patients with ischemic cardiomyopathy relies only on viable myocardium extent, whereas both the amount of viable and scar tissue may be important. A model was developed, based on the amount of viable and nonviable myocardium, to predict functional recovery. Viable and scarred myocardium was defined by dobutamine stress echocardiography (DSE) in 108 consecutive patients. LVEF before and 9 to 12 months after revascularization was assessed by radionuclide ventriculography; an improvement of ≥5% was considered significant. In the 1,089 dysfunctional segments (63%), DSE elicited biphasic response in 216 segments (20%), sustained improvement in 205 (19%), worsening in 43 (4%), and no change in 625 (57%). LVEF improved in 39 patients (36%). Only the numbers of biphasic and scar segments were predictors of improvement or no improvement of LVEF (odds ratio 1.5, 95% confidence interval 1.2 to 1.7, p <0.0001 for biphasic segments; odds ratio 0.8, 95% confidence interval 0.7 to 0.9, p <0.0005 for scarred segments). The sustained improvement and worsening pattern were not predictive of improvement or no improvement. A regression function, based on the number of scar and biphasic segments, showed that the likelihood of recovery was 85% in patients with extensive biphasic tissue and no scars and 11% in patients with extensive scars and no biphasic myocardium. Patients with a mixture of scar and biphasic tissue had an intermediate likelihood of improvement (50%). In patients with ischemic cardiomyopathy and a mixture of viable and nonviable tissue, both numbers of viable and nonviable segments should be considered to accurately predict functional recovery after revascularization.  相似文献   
66.
Three-dimensional treatment planning for lung cancer   总被引:4,自引:0,他引:4  
The experience of four institutions involved in a three-dimensional treatment planning contract (NCI) for lung cancer is described. It was found that three-dimensional treatment planning has a significant potential for optimization of treatment plans for radiotherapy of lung cancer both for tumor coverage and sparing of critical normal tissues within the complex anatomy of the human thorax. Evaluation tools, such as dose-volume histograms, and three-dimensional isodose displays, such as multiple plane views, surface dose displays, etc., were found to be extremely valuable in evaluation and comparison of these complex plans. It is anticipated that with further developments in three-dimensional simulation and treatment delivery systems, major progress towards uncomplicated local regional control of lung cancer may be forthcoming.  相似文献   
67.
Statins are potent inhibitors of cholesterol synthesis. Several statins are available with different molecular and pharmacokinetic properties. Simvastatin is more lipophilic than pravastatin and has a higher affinity to phospholipid membranes than atorvastatin, allowing its passive diffusion through the cell membrane. In vitro studies on bone marrow stromal cells, osteoblast‐like cells, and embryonic stem cells have shown statins to have cholesterol‐independent anabolic effects on bone metabolism; alas, statins were supplemented in osteogenic medium, which does not facilitate elucidation of their potential osteoinductive properties. Embryonic stem cells (ESCs), derived from the inner cell mass of the blastocyst, are unique in that they enjoy perpetual self‐proliferation, are pluripotent, and are able to differentiate toward all the cellular lineages composing the body, including the osteogenic lineage. Consequently, ESCs represent a potentially potent cell source for future clinical cellular therapies of various bone diseases, even though there are several hurdles that still need to be overcome. Herein we demonstrate, for the first time to our knowledge, that simvastatin induces murine ESC (mESC) differentiation toward the osteogenic lineage in the absence of osteoinductive supplements. Specifically, we found that a simvastatin concentration in the micromolar range and higher was toxic to the cells and that an effective concentration for osteoinduction is 0.1 nM, as shown by increased alizarin red staining as well as increased osteocalcin and osetrix gene expression. These results suggest that in the future, lipophilic simvastatin may provide a novel pharmacologic agent for bone tissue engineering applications. © 2010 American Society for Bone and Mineral Research.  相似文献   
68.
The clinical profiles of 139 patients with gallstones found coincidentally during ultrasonography were reviewed and the patients followed prospectively for five years. Indications for ultrasonography included follow-up of abdominal malignancy (33%), evaluation of abdominal aortic aneurysm or other arteriosclerotic vascular disease (22%), renal insufficiency (12%), and lower abdominal pain (7%). At the time of gallstone detection, 14 patients (10%) had symptoms attributable to cholelithiasis. Over the next five years, only 15 patients (11%) developed episodes resembling biliary pain. Nine patients underwent cholecystectomy during this period. Three of the cholecystectomies were incidental to other abdominal procedures. Two cholecystectomies were performed as emergencies for gallstone complications with no perioperative mortality. Interestingly, 54 patients (40%) with coincidental gallstones died during the follow-up period. All the deaths were unrelated to gallstones. These data indicate that Ultrasonographically detected coincidental gallstones rarely have clinical significance, lending strong support to the expectant management of most patients with purely coincidental gallstones.  相似文献   
69.
A multi-institutional study was undertaken using computerized planning systems to develop three-dimensional (3-D) radiotherapy plans for Hodgkin's disease (H.D.). Two patients, the first afflicted with bulky stage II disease and another one with early stage I H.D., were studied. Three main categories of plan were produced for each patient: a) a traditional plan which modelled a conventional mantle treatment on the 3-D system, b) a 3-D standard plan where anterior and posterior fields were designed to cover 3-D target volumes, and c) a 3-D unconstrained plan where innovational techniques were employed. Three-dimensional planning provides information about the dose distribution throughout the large volume irradiated in patients with H.D. that is not available with conventional mantle planning. The use of 3-D techniques resulted in improved tumor coverage, but by allowing for uncertainties such as motion, the doses to normal tissues tended to be higher. The use of unorthodox beam arrangements introduced added complexities, and further increased the lung doses. The most even dose distributions were obtained by incorporating compensating filters into anterior fields. Clinicians showed wide variations in their assessment of the plans, possible reasons for which are addressed in this paper. In addition, calculated probabilities from models of tumor control and normal tissue damage are also presented.  相似文献   
70.
Lymphotoxin (LT)α knockout mice, as well as double LTα/tumor necrosis factor (TNF) knockout mice, show a severe splenic disorganization with nonsegregating T/B cell zones and complete absence of primary B cell follicles, follicular dendritic cell (FDC) networks, and germinal centers. In contrast, as shown previously and confirmed in this study, LTβ-deficient mice show much more conserved T/B cell areas and a reduced but preserved capacity to form germinal centers and FDC networks. We show here that similar to the splenic phenotype of LTβ-deficient mice, complementation of LTα knockout mice with TNF-expressing transgenes leads to a p55 TNF receptor–dependent restoration of B/T cell zone segregation and a partial preservation of primary B cell follicles, FDC networks, and germinal centers. Notably, upon lipopolysaccharide challenge, LTα knockout mice fail to produce physiological levels of TNF both in peritoneal macrophage supernatants and in their serum, indicating a coinciding deficiency in TNF expression. These findings suggest that defective TNF expression contributes to the complex phenotype of the LTα knockout mice, and uncover a predominant role for TNF and its p55 TNF receptor in supporting, even in the absence of LTα, the development and maintenance of splenic B cell follicles, FDC networks, and germinal centers.  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