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   777篇
  免费   55篇
  国内免费   14篇
耳鼻咽喉   2篇
儿科学   56篇
妇产科学   25篇
基础医学   97篇
口腔科学   11篇
临床医学   55篇
内科学   124篇
皮肤病学   19篇
神经病学   44篇
特种医学   143篇
外科学   87篇
综合类   21篇
一般理论   8篇
预防医学   54篇
眼科学   20篇
药学   43篇
肿瘤学   37篇
  2021年   11篇
  2019年   9篇
  2018年   11篇
  2017年   5篇
  2016年   14篇
  2015年   16篇
  2014年   12篇
  2013年   17篇
  2012年   17篇
  2011年   27篇
  2010年   32篇
  2009年   37篇
  2008年   20篇
  2007年   38篇
  2006年   30篇
  2005年   28篇
  2004年   35篇
  2003年   17篇
  2002年   21篇
  2001年   26篇
  2000年   10篇
  1999年   10篇
  1998年   24篇
  1997年   38篇
  1996年   22篇
  1995年   26篇
  1994年   19篇
  1993年   8篇
  1992年   10篇
  1991年   10篇
  1990年   14篇
  1989年   16篇
  1988年   16篇
  1987年   21篇
  1986年   14篇
  1985年   12篇
  1984年   11篇
  1983年   12篇
  1982年   8篇
  1981年   13篇
  1980年   17篇
  1979年   13篇
  1978年   5篇
  1977年   10篇
  1976年   11篇
  1975年   13篇
  1974年   8篇
  1973年   6篇
  1971年   4篇
  1967年   5篇
排序方式: 共有846条查询结果,搜索用时 0 毫秒
1.
2.
Abstrakt 1. Nimmt ein Patient einen ihm von seinem (Zahn-)Arzt einger?umten Exklusiv-Termin nicht wahr, obwohl er auf dessen Eigenschaft ausdrücklich hingewiesen wurde, so hat er dem (Zahn-)Arzt den Behandlungsausfall abzüglich eines angemessenen Eigenanteils des (Zahn-)Arztes zu ersetzen. 2. Die Ersatzpflicht tritt auch dann ein, wenn der Patient den Termin nicht in der in dem Behandlungsvertrag vorgesehenen Frist absagt. Eine hierfür seitens des (Zahn-)Arztes bestimmte Frist von zwei Tagen vor Behandlungsbeginn stellt sich für den Patienten grunds?tzlich auch nicht als unangemessene Benachteiligung i.S. des § 307 BGB dar. 3. Ein Anspruch des Arztes entf?llt auch bei nur mündlicher Vereinbarung nicht unter dem Gesichtspunkt des § 4 Abs. 5b BMV-Z, denn diese Vorschrift ist teleologisch dahin zu reduzieren, dass nur zahn?rztliche Honoraransprüche aus erfolgten Behandlungen schriftlich vereinbart werden müssen. Soweit es jedoch um einen vertraglichen Anspruch wegen einer Leistungsst?rung geht, vermag das Schriftformerfordernis des § 4 Abs. 5b BMV-Z grunds?tzlich nicht einzugreifen. (Leits?tze des Bearbeiters)  相似文献   
3.
Early during rat thymus ontogeny, an important proportion of thymocytes expresses IL-2R and contains IL-2 mRNA. To investigate the role of the IL-2-IL-2R complex in rat T cell maturation, we supplied either recombinant rat IL-2 or blocking anti-CD25 mAb to rat fetal thymus organ cultures (FTOC) under several experimental conditions. The IL-2 treatment initially stimulated the growth of thymocytes and, as a result, induced T cell differentiation, but the continuous addition of IL-2 to rat FTOC, as well as the anti-CD25 administration, resulted in cell number decrease and inhibition of thymocyte maturation. These results indicate that immature rat thymocytes bear functional high- affinity IL-2R and that IL-2 promotes T cell differentiation as a consequence of its capacity to stimulate cell proliferation. Modifications in TCR alpha beta repertoire and increased numbers of NKR- P1+ cells, largely NK cells, were also observed in IL-2-treated FTOC. Furthermore, IL-2-responsiveness of different thymocyte subsets changed throughout thymic ontogeny. Immature CD4-CD8-cells responded to IL-2 in two stages, early in thymus development and around birth, in correlation with the maturation of two distinct waves of thymic cell progenitors. Mature CD8+ thymocytes maximally responded to IL-2 around birth, supporting a role for IL-2 in the increased proliferation of mature thymocytes observed in vivo in the perinatal period. Taken together, these findings support a role for IL-2 in rat T cell development.   相似文献   
4.
Life expectancy in British Marfan syndrome populations   总被引:2,自引:0,他引:2  
A total of 206 patients with Marfan syndrome were ascertained throughout genetic clinics in Wales and Scotland during the period 1970–1990. There were 45 deaths representing 22% of the cohort. Mean age at death was 45.3 ± 16.5 years. 50% median cumulative survival in the total cohort (n = 206) was 53 years for males and 72 years for females. Multivariate analysis confirmed severity as the best independent indicator of survival. These findings and survival curves will assist in the counselling of British families and individuals with Marfan syndrome.  相似文献   
5.
Approximately 80% of Americans live in cities or immediately adjacent communities. Such urban environments are complex amalgams of people of disparate backgrounds, economic status, and expectations, with extraordinary disparities in health status and outcomes between groups just blocks apart. Urban health as a framing paradigm is of recent vintage and offers a perspective on health and disease that integrates clinical medicine and public health and draws on the social and political sciences to seek understanding of the impact of cities on the health of populations and individuals. Ironically, disparate outcomes and increased mortality among poor minority populations in cities are not primarily related to the consequences of the urban epidemics of drugs and violence but rather are due to the increased prevalence and severity of common diseases such as asthma, cardiovascular disease, diabetes, and kidney disease. Several factors may be responsible for such disparities, including stress, racism, perceptions of deprivation, economic inequalities, and lack of access to quality health care. It is time for leaders in medical education and health care delivery to focus on the populations that surround their institutions in order to study urban health and meet the challenge of caring for all the residents of our cities.  相似文献   
6.
Growth of human connective tissue progenitor cells (CTPs) was characterized on smooth and microtextured polydimethylsiloxane (PDMS) surfaces. Human bone marrow derived cells were cultured for nine days under conditions promoting osteoblastic differentiation on Smooth PDMS and PDMS Channel microtextures (11 m high, 45 m wide channels, and separated by 5 m wide ridges). Glass tissue culture dish surfaces were used as controls. Cell numbers per colony, cell density within colonies, alignment of cells, area of colonies, and colony shapes were determined as a function of substrate surface topography. An alkaline phosphatase stain was used as a marker for osteoblastic phenotype. CTPs attached, proliferated, and differentiated on all surfaces with cell process lengths of up to 80 m. Cells on the Smooth PDMS and control surfaces spread and proliferated as colonies in proximity to other cells and migrated in random directions creating colonies that covered significantly larger areas (0.96 and 1.05 mm2, respectively) than colonies formed on PDMS Channel textures (0.64 mm2). In contrast, cells on PDMS Channel textures spread, proliferated, aligned along the channel axis, and created colonies that were more dense, and with lengths of longest colony axes that were significantly longer (3252 m) than those on the Smooth PDMS (1265 m) and control surfaces (1319 m). Cells on PDMS Channel textures were aligned at an angle of 14.44° relative to the channel axis, and the resulting colonies exhibited a significantly higher aspect ratio (13.72) compared to Smooth PDMS (1.57) and control surfaces (1.51).  相似文献   
7.
BackgroundChronic nonsteroidal anti-inflammatory drug (NSAID) use is associated with gastrointestinal bleeding via inhibition of endogenous mucosal protection and platelet aggregation. This study aimed to determine whether extended NSAIDs after joint arthroplasty is associated with increased risk of gastrointestinal bleeding.MethodsThis was a retrospective study examining 28,794 adults who underwent joint arthroplasty by one of 50 surgeons from 2016 to 2018. Episodes of gastrointestinal bleeding within 90 days postoperatively were identified prospectively. Postoperative medications were reported directly by patients with electronic questionnaires. The primary analysis was performed using binary logistic regression.ResultsA total of 74 (0.26%) episodes of gastrointestinal bleeding occurred within 90 days (median 8 days) postoperatively. Of 5086 patients with complete data included in the primary analysis, 59.6% had used NSAIDs with median duration of 2 weeks (interquartile range, 0-6 weeks). Patients with gastrointestinal bleeding were significantly older (71.3 vs 67.0 years), required longer hospitalizations (2.1 vs 1.5 days), and more commonly had a history of peptic ulcers (10.8% vs 0.9%). However, there was no positive association between NSAID use and gastrointestinal bleeding. In fact, the odds of gastrointestinal bleeding were lower in patients taking NSAIDs. Gastrointestinal bleeding was associated with anticoagulants, antiplatelet agents, and, to a lesser extent, aspirin.ConclusionNSAIDs were not associated with gastrointestinal bleeding and may be prescribed safely for a majority of patients after joint arthroplasty. The greatest odds of gastrointestinal bleeding occurred in patients with peptic ulcer disease and those who received antiplatelet and anticoagulation agents. Increasing age and bilateral surgery were also associated with gastrointestinal bleeding.Level of EvidenceLevel III.  相似文献   
8.
1-Amino-2,4-dibromoanthraquinone (ADBAQ), an intermediate in the production of commercial dyes for wool, silk, and synthetic fibers, was selected for toxicology and carcinogenesis studies in two rodent species. In advance of the 2-year studies, 13-week studies were conducted in male and female F344/N rats and B6C3F1 mice which were fed a diet containing ADBAQ at concentrations of 0, 0.25, 0.50, 1.00, 2.50, and 5.00%. ADBAQ stained the skin and fur red at all doses in rats and at 1.00% and higher concentrations in mice. Lethargy and emaciation were noted at the 2.50% and higher doses in rats of both sexes. In general, the absolute weight of the liver and the liver/organ weight ratios increased in both sexes and species at all doses. Treated rats developed a chronic toxic hepatitis characterized by hepatocytomegaly, centrilobular vacuolar degeneration and necrosis, regenerative nodules, acute necrotizing cholangitis, bile duct hyperplasia, chronic active inflammation in periportal areas, and focal pigmentation. The hepatopathy occurred at all doses in males and at 0.50% and higher in females and correlated with elevations of serum glutamic-pyruvic and glutamic-oxaloacetic transaminases, leukocytosis, and neutrophilia. Hyaline droplet degeneration in the proximal convoluted tubules of the kidneys occurred in male rats, and uterine atrophy was observed in female rats at 1.00% and higher. Anemia occurred in both sexes of rats at all doses and thymic atrophy was observed in both sexes of high-dose rats. In male mice minimal dose-related lesions in the liver included centrilobular glycogen depletion at 1.00% and higher and pigmentation at all doses. At comparable doses, ADBAQ was considered to be markedly toxic in rats and of minimal nonlife-threatening toxicity in mice.  相似文献   
9.
We have evaluated the fibrinogen/fibrin fragment E antigen assay as a diagnostic test in patients with clinically suspected venous thrombosis by comparing the results of this assay with venography in 272 patients. The result of the fragment E antigen assay was elevated in 79 of 80 patients with positive venograms for recent venous thrombosis (sensitivity 99%) and within the normal range in 161 of 192 patients with normal venograms (specificity 84%). The fragment E assay was also evaluated in 130 medical and surgical controls without evidence of venous thrombosis by leg scanning and the test was found to be relatively nonspecific. However, in the patient group under study, a correct clinical diagnosis of no thrombosis, based on a normal fragment E result, was made in 161 of 162 cases (negative predictive value of 99%). Therefore, a normal test result effectively excludes a diagnosis of venous thrombosis in clinically symptomatic patients. The assay, as currently performed, is technically demanding and takes 24 hr to complete. Therefore, it will have to be simplified before it can be applied to clinical practice.  相似文献   
10.
G Iosif  J Fleischman  R Chitkara 《Chest》1991,99(6):1538-1539
Empyema developing seven weeks after craniotomy in a 62-year-old black woman with an ipsilateral ventriculopleural (V-PL) shunt is described. Infection of the pleural space presumably resulted from transfer of organisms from a proximal V-PL shunt infection to the thorax. Empyema resulting from V-PL shunt infection has not previously been reported. Pleural effusions in patients with V-PL shunts must be considered as a potential site of infection with possible development of empyema.  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