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   5990篇
  免费   360篇
  国内免费   43篇
耳鼻咽喉   60篇
儿科学   108篇
妇产科学   55篇
基础医学   1072篇
口腔科学   66篇
临床医学   486篇
内科学   1071篇
皮肤病学   125篇
神经病学   717篇
特种医学   309篇
外科学   907篇
综合类   16篇
一般理论   3篇
预防医学   146篇
眼科学   236篇
药学   382篇
中国医学   14篇
肿瘤学   620篇
  2024年   4篇
  2023年   50篇
  2022年   93篇
  2021年   142篇
  2020年   109篇
  2019年   134篇
  2018年   143篇
  2017年   113篇
  2016年   177篇
  2015年   218篇
  2014年   243篇
  2013年   311篇
  2012年   466篇
  2011年   475篇
  2010年   289篇
  2009年   273篇
  2008年   408篇
  2007年   431篇
  2006年   404篇
  2005年   428篇
  2004年   387篇
  2003年   337篇
  2002年   283篇
  2001年   67篇
  2000年   43篇
  1999年   33篇
  1998年   50篇
  1997年   28篇
  1996年   32篇
  1995年   23篇
  1994年   27篇
  1993年   20篇
  1992年   13篇
  1991年   15篇
  1990年   9篇
  1989年   12篇
  1988年   3篇
  1987年   4篇
  1986年   6篇
  1985年   7篇
  1984年   6篇
  1983年   14篇
  1982年   12篇
  1981年   6篇
  1980年   3篇
  1979年   5篇
  1978年   7篇
  1977年   4篇
  1972年   6篇
  1965年   4篇
排序方式: 共有6393条查询结果,搜索用时 0 毫秒
61.
In a context of therapeutic revolution in older adults with AML, it is becoming increasingly important to select patients for the various treatment options by taking account of short-term efficacy and toxicity as well as long-term survival. Here, the data from three European registries for 1,199 AML patients aged 70 years or older treated with intensive chemotherapy were used to develop a prognostic scoring system. The median follow-up was 50.8 months. In the training set of 636 patients, age, performance status, secondary AML, leukocytosis, and cytogenetics, as well as NPM1 mutations (without FLT3-ITD), were all significantly associated with overall survival, albeit not to the same degree. These factors were used to develop a score that predicts long-term overall survival. Three risk-groups were identified: a lower, intermediate and higher-risk score with predicted 5-year overall survival (OS) probabilities of ≥12% (n = 283, 51%; median OS = 18 months), 3–12% (n = 226, 41%; median OS = 9 months) and <3% (n = 47, 8%; median OS = 3 months), respectively. This scoring system was also significantly associated with complete remission, early death and relapse-free survival; performed similarly in the external validation cohort (n = 563) and showed a lower false-positive rate than previously published scores. The European Scoring System ≥70, easy for routine calculation, predicts long-term survival in older AML patients considered for intensive chemotherapy.Subject terms: Acute myeloid leukaemia, Risk factors  相似文献   
62.
63.
64.

Introduction

The assessment of papillary lesions continues to be a challenging area in breast radiology and pathology. The management of intraductal papillomas without atypia of the breast remains controversial. The purpose of the present study was to determine diagnostic accuracy of radiographical diagnosis, core biopsy, and surgical excision in papillary breast lesions.

Material and methods

By using files from 1995 to 2010, 151 cases of intraductal papilloma with or without atypia were identified. Patients were stratified as follows: core biopsy followed by surgical excision (n = 61), core biopsy alone (n = 19), and surgical excision alone (n = 71).

Results

The upstage rate of intraductal papillomas without atypia on core biopsy to atypia or malignancy on excision was 8.9%. Excision specimens revealed intraductal papillomas without atypia in 68 out of 71 cases, and atypical papillomas in 3 cases.

Conclusion

Our findings suggest that radiographic and histopathological diagnosis of intraductal papillomas show high accuracy and good concordance. In cases where the radiographic diagnosis reveals suspicious lesions core biopsy represents the first choice.  相似文献   
65.
(1) Background: Mitochondria are the cells’ main source of energy. Mitochondrial dysfunction represents a key hallmark of aging and is linked to the development of Alzheimer’s disease (AD). Maintaining mitochondrial function might contribute to healthy aging and the prevention of AD. The Mediterranean diet, including walnuts, seems to prevent age-related neurodegeneration. Walnuts are a rich source of α-linolenic acid (ALA), an essential n3-fatty acid and the precursor for n3-long-chain polyunsaturated fatty acids (n3-PUFA), which might potentially improve mitochondrial function. (2) Methods: We tested whether a lipophilic walnut extract (WE) affects mitochondrial function and other parameters in human SH-SY5Y cells transfected with the neuronal amyloid precursor protein (APP695). Walnut lipids were extracted using a Soxhlet Extraction System and analyzed using GC/MS and HPLC/FD. Adenosine triphosphate (ATP) concentrations were quantified under basal conditions in cell culture, as well as after rotenone-induced stress. Neurite outgrowth was investigated, as well as membrane integrity, cellular reactive oxygen species, cellular peroxidase activity, and citrate synthase activity. Beta-amyloid (Aβ) was quantified using homogenous time-resolved fluorescence. (3) Results: The main constituents of WE are linoleic acid, oleic acid, α-linolenic acid, and γ- and δ-tocopherol. Basal ATP levels following rotenone treatment, as well as citrate synthase activity, were increased after WE treatment. WE significantly increased cellular reactive oxygen species but lowered peroxidase activity. Membrane integrity was not affected. Furthermore, WE treatment reduced Aβ1–40 and stimulated neurite growth. (4) Conclusions: WE might increase ATP production after induction of mitochondrial biogenesis. Decreased Aβ1–40 formation and enhanced ATP levels might enhance neurite growth, making WE a potential agent to enhance neuronal function and to prevent the development of AD. In this sense, WE could be a promising agent for the prevention of AD.  相似文献   
66.
67.
68.
Prostate cancer is the most common malignancy, accounting for about 25% of all incident cases among men in industrialized countries. The human androgen-dependent prostate cancer cell line LNCaP, which is derived from a metastatic lesion of human prostatic adenocarcinoma, is frequently used to study prostate cancer associated signaling pathways in vitro. Recently it was described that Rho GTPase activation in these cells leads to apoptotic responses. We used the bacterial toxins CNFy and CNF1, which specifically and directly activate Rho GTPases by deamidation of a single glutamine. We asked whether these Rho activators could induce apoptosis in LNCaP cells. Our results indicate that RhoA activation, induced by CNFy, does lead to intrinsic apoptosis of the cells. Analysis of the underlying signaling pathway reveals that apoptosis induction requires the activity of Rho kinase (ROCK) and myosin activation, an apoptotic pathway previously identified in cancer stem cells.  相似文献   
69.
70.
ObjectiveThe aim of this study was to develop an algorithm for scheduling pick-up and delivery tasks in hospitals. The number of jobs and the dynamic nature of the problem, in having jobs arriving over time, makes the use of information technology indispensable. An optimized scheduling for all types of transportation tasks occurring in a hospital accelerates medical procedures, and reduces the patient’s waiting time and costs.MethodsIn the design of the algorithm we use techniques from classical scheduling theory. In addition, due to some special properties and constraints, we model the problem using methods from graph theory. The resulting algorithm combines both approaches in a transparent manner.ConclusionsTo optimize the schedules, we define the average weighted flow time as an objective function that corresponds to a measure for the task throughput. An evaluation of the algorithm at the Natters State Hospital in Austria shows that it has a superior performance than the current scheduling mechanism.  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