首页 | 官方网站   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   1970篇
  免费   154篇
  国内免费   3篇
医药卫生   2127篇
  2023年   11篇
  2022年   14篇
  2021年   46篇
  2020年   53篇
  2019年   48篇
  2018年   54篇
  2017年   58篇
  2016年   52篇
  2015年   48篇
  2014年   65篇
  2013年   106篇
  2012年   162篇
  2011年   127篇
  2010年   91篇
  2009年   76篇
  2008年   118篇
  2007年   138篇
  2006年   127篇
  2005年   126篇
  2004年   106篇
  2003年   93篇
  2002年   103篇
  2001年   29篇
  2000年   20篇
  1999年   25篇
  1998年   19篇
  1997年   15篇
  1996年   9篇
  1995年   13篇
  1994年   9篇
  1993年   12篇
  1992年   5篇
  1991年   12篇
  1989年   3篇
  1988年   3篇
  1987年   7篇
  1986年   11篇
  1985年   22篇
  1984年   5篇
  1983年   8篇
  1982年   8篇
  1980年   3篇
  1979年   6篇
  1978年   5篇
  1977年   3篇
  1974年   5篇
  1972年   3篇
  1971年   4篇
  1939年   4篇
  1929年   3篇
排序方式: 共有2127条查询结果,搜索用时 312 毫秒
11.
Primary antitumor immune response mediated by CD4+ T cells   总被引:7,自引:0,他引:7  
Gene-targeted mice have recently revealed a role for lymphocytes and interferon-gamma (IFNgamma) in conferring protection against cancer, but the mechanisms remain unclear. Here, we have characterized a successful primary antitumor immune response initiated by naive CD4+ T cells. Major histocompatibility complex class II (MHC-II)-negative myeloma cells injected subcutaneously into syngeneic mice were surrounded within 3 days by macrophages that captured tumor antigens. Within 6 days, naive myeloma-specific CD4+ T cells became activated in draining lymph nodes and subsequently migrated to the incipient tumor site. Upon recognition of tumor-derived antigenic peptides presented on MHC-II by macrophages, the myeloma-specific CD4+ T cells were reactivated and started to secrete cytokines. T cell-derived IFNgamma activated macrophages in close proximity to the tumor cells. Tumor cell growth was completely inhibited by such locally activated macrophages. These data indicate a mechanism for immunosurveillance of MHC-II-negative cancer cells by tumor-specific CD4+ T cells through collaboration with macrophages.  相似文献   
12.
The modulation transfer function (MTF) describes the spatial resolution properties of imaging systems. In this work, the accuracy of our implementation of the edge method for calculating the presampled MTF was examined. Synthetic edge images with known MTF were used as gold standards for determining the robustness of the edge method. These images simulated realistic data from clinical digital mammography systems, and contained intrinsic system factors that could affect the MTF accuracy, such as noise, scatter, and flat-field nonuniformities. Our algorithm is not influenced by detector dose variations for MTF accuracy up to 1/2 the sampling frequency. We investigated several methods for noise reduction, including truncating the supersampled line spread function (LSF), windowing the LSF, applying a local exponential fit to the LSF, and applying a monotonic constraint to the supersampled edge spread function. Only the monotonic constraint did not introduce a systematic error; the other methods could result in MTF underestimation. Overall, our edge method consistently computed MTFs which were in good agreement with the true MTF. The edge method was then applied to images from a commercial storage-phosphor based digital mammography system. The calculated MTF was affected by the size (sides of 2.5, 5, or 10 cm) and the composition (lead or tungsten) of the edge device. However, the effects on the MTF were observed only with regard to the low frequency drop (LFD). Scatter nonuniformity was dependent on edge size, and could lead to slight underestimation of LFD. Nevertheless, this negative effect could be minimized by using an edge of 5 cm or larger. An edge composed of lead is susceptible to L-fluorescence, which causes overestimation of the LFD. The results of this work are intended to underline the need for clear guidelines if the MTF is to be given a more crucial role in acceptance tests and routine assessment of digital mammography systems: the MTF algorithm and edge object test tool need to be publicly validated.  相似文献   
13.
ObjectivesAbiraterone acetate is registered for the treatment of metastatic castration-sensitive and resistant prostate cancer (mCRPC). Treatment outcome is associated with plasma trough concentrations (Cmin) of abiraterone. Patients with a plasma Cmin below the target of 8.4 ng/mL may benefit from treatment optimization by dose increase or concomitant intake with food. This study aims to investigate the cost-effectiveness of monitoring abiraterone Cmin in patients with mCRPC.MethodsA Markov model was built with health states progression-free survival, progressed disease, and death. The benefits of monitoring abiraterone Cmin followed by a dose increase or food intervention were modeled via a difference in the percentage of patients achieving adequate Cmin taking a healthcare payer perspective. Deterministic and probabilistic sensitivity analyses were performed to assess uncertainties and their impac to the incremental cost-effectiveness ratio (ICER).ResultsMonitoring abiraterone followed by a dose increase resulted in 0.149 incremental quality-adjusted life-years (QALYs) with €22 145 incremental costs and an ICER of €177 821/QALY. The food intervention assumed equal effects and estimated incremental costs of €7599, resulting in an ICER of €61 019/QALY. The likelihoods of therapeutic drug monitoring (TDM) with a dose increase or food intervention being cost-effective were 8.04%and 81.9%, respectively.ConclusionsMonitoring abiraterone followed by a dose increase is not cost-effective in patients with mCRPC from a healthcare payer perspective. Monitoring in combination with a food intervention is likely to be cost-effective. This cost-effectiveness assessment may assist decision making in future integration of abiraterone TDM followed by a food intervention into standard abiraterone acetate treatment practices of mCRPC patients.  相似文献   
14.

Special Articles

Long-term care bioethics committees: A cooperative model  相似文献   
15.
16.
PURPOSE: Recent studies have found an association between certain TP53 mutations and resistance to anthracycline-based primary medical therapy in breast cancer. The purpose of this study was to investigate whether TP53 mutational status also might influence the response to a non-anthracycline-containing regimen in primary breast cancer. EXPERIMENTAL DESIGN: Thirty-five patients with locally advanced breast cancer were investigated for TP53 mutations before receiving combination chemotherapy with 5-fluorouracil (1000 mg/m(2) on days 1 and 2) and mitomycin (6 mg/m(2) on day 2), administered every 3 weeks for 2-10 cycles in the neoadjuvant setting. RESULTS: Mutations in the TP53 gene, in particular those affecting loop domains L2 or L3 of the p53 protein, were associated with lack of response to chemotherapy (i.e., increase in the diameter product of tumor lesion by >/=25%; P = 0.177 for all mutations and P = 0.006 for those affecting L2/L3 domains, respectively). No statistically significant correlation between TP53 LOH and response to therapy was seen. CONCLUSION: This study revealed a significant association between lack of response to 5-fluorouracil and mitomycin and mutations affecting the L2/L3 domains of the p53 protein. Together with our previous finding that such mutations predict resistance to weekly doxorubicin, our data suggest that mutations affecting this particular domain of the p53 protein may cause resistance to several different cytotoxic compounds applied in breast cancer treatment.  相似文献   
17.
Objective: Motivation is suggested as an important factor in pediatric motor rehabilitation. Therefore, we reviewed the existing evidence of (motivational) motor rehabilitation paradigms, and how motivation influences rehabilitation outcome using self-determination theory as conceptual framework. Methods: PubMed and Web-of-Science databases were systematically searched until June 2015. Data were independently extracted and critiqued for quality by three authors. Studies reporting motivational aspects were included. Most studies examined new technology (e.g., virtual reality [VR]). Results: Out of 479 records, three RCT, six case-control, and six non-comparative studies were included with mixed quality. Motivation was rarely reported. Training individualization to the child’s capabilities with more variety seemed promising to increase motivation. Motivation increased when the exercises seemed helpful for daily activities. Conclusions: Motivation in pediatric rehabilitation should be comprehensively assessed within a theoretical framework as there are indications that motivated children have better rehabilitation outcomes, depending on the aspect of motivation.  相似文献   
18.
19.
ObjectivesTo provide overview of research on training interventions for healthcare providers aimed at promoting competencies in delivering group-based patient education.MethodsA systematic literature search identified relevant studies. Data was extracted on training details, study design, outcomes and experiences. Results were summarized and qualitative data analyzed using content analysis.ResultsTwenty-seven studies exploring various training interventions were included. Ten studies used qualitative methods, eight quantitative and nine mixed methods. Use of a comparison group, validated instruments and follow-up measures was rare. Healthcare providers’ reactions to training were mostly positive. Several studies indicated positive short-term effects on self-efficacy and knowledge. Results on observed skills and patient outcomes were inconclusive. Results on healthcare providers’ experience of delivery of group-based patient education following training were categorized into 1) Benefits of training interventions, 2) Barriers to implementation and 3) Delivery support.ConclusionsFurther evaluation of training for healthcare providers delivering group-based patient education is needed before conclusions on training efficacy can be drawn. The results indicate an expanding research field still in maturation.Practice implicationsEfficacy studies evaluating theoretically grounded training with clear attention on group facilitation and follow-up support are needed. Inclusion of validated instruments and long-term outcomes is encouraged.  相似文献   
20.
Congenital aniridia is a rare panocular disease caused by fundamental disturbances in the development of the eye, characterized primarily by hypoplasia of the iris and macula. Severe secondary complications such as keratopathy, cataract, and glaucoma are common and often lead to considerable visual impairment or blindness. Many complications in aniridia patients are difficult to treat and present a challenge for the ophthalmologist. Increasingly, associated nonocular features of the disease are also being recognized. Over the past decades, major steps have been made in the understanding of the genetic basis of aniridia. Moreover, recent studies have prepared the ground for future treatment options based on specific mutations. Therefore, specific knowledge about genetics in aniridia has become more important than ever. We provide an overview of the field of aniridia genetics and its clinical implications.  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-23

京公网安备 11010802026262号