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   820篇
  免费   84篇
  国内免费   7篇
耳鼻咽喉   2篇
儿科学   19篇
妇产科学   7篇
基础医学   92篇
口腔科学   2篇
临床医学   76篇
内科学   39篇
皮肤病学   1篇
神经病学   62篇
特种医学   293篇
外科学   33篇
综合类   112篇
预防医学   59篇
药学   45篇
中国医学   5篇
肿瘤学   64篇
  2024年   1篇
  2023年   6篇
  2022年   25篇
  2021年   28篇
  2020年   30篇
  2019年   45篇
  2018年   57篇
  2017年   65篇
  2016年   40篇
  2015年   41篇
  2014年   83篇
  2013年   83篇
  2012年   56篇
  2011年   73篇
  2010年   45篇
  2009年   39篇
  2008年   43篇
  2007年   28篇
  2006年   24篇
  2005年   14篇
  2004年   23篇
  2003年   13篇
  2002年   14篇
  2001年   4篇
  2000年   1篇
  1999年   4篇
  1998年   1篇
  1997年   2篇
  1996年   2篇
  1994年   1篇
  1993年   2篇
  1992年   2篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1981年   4篇
  1980年   1篇
  1979年   1篇
  1975年   2篇
  1971年   1篇
  1968年   1篇
排序方式: 共有911条查询结果,搜索用时 15 毫秒
11.
Prostate cancer (PCa) is the second most common cancer in men. The Gleason score (GS) and biomarkers play important roles in the diagnosis and treatment of patients with PCa. The purpose of this study was to investigate the relationship between the apparent diffusion coefficient (ADC) and the molecular markers Ki‐67, hypoxia‐inducible factor‐1α (HIF‐1α) and vascular endothelial growth factor (VEGF) in PCa. Thirty‐nine patients with 39 lesions, who had been diagnosed with PCa, were enrolled in this study. All patients underwent diffusion‐weighted magnetic resonance imaging (DW‐MRI) (b = 800 s/mm2). The expression of Ki‐67, HIF‐1α and VEGF was assessed by immunohistochemistry. Statistical analysis was applied to analyze the association between ADC and prostate‐specific antigen (PSA), GS and the expression of Ki‐67, HIF‐1α and VEGF. The group differences in ADC among different grades of Ki‐67, HIF‐1α and VEGF were also analyzed. The mean ± standard deviation of ADC was (0.76 ± 0.27) × 10?3 mm2/s. ADC correlated negatively with PSA and GS (p < 0.05). The Ki‐67 staining index (SI), HIF‐1α expression and VEGF expression in PCa were correlated inversely with ADC, controlling for age (r = –0.332, p < 0.05; r = ?0.662, p < 0.0005; and r = ?0.714, p < 0.0005, respectively). ADC showed a significant difference among different grades of Ki‐67 (F = 9.164, p = 0.005), HIF‐1α (F = 40.333, p < 0.0005) and VEGF (F = 22.048, p < 0.0005). In conclusion, ADC was correlated with PSA, GS, and Ki‐67, HIF‐1α and VEGF expression in patients with PCa. ADC may be used to evaluate tumor proliferation, hypoxia and angiogenesis in PCa.  相似文献   
12.
The combination of hyperpolarized MRS with diffusion weighting (dw) allows for determination of the apparent diffusion coefficient (ADC), which is indicative of the intra‐ or extracellular localization of the metabolite. Here, a slice‐selective pulsed‐gradient spin echo sequence was implemented to acquire a series of dw spectra from rat muscle in vivo to determine the ADCs of multiple metabolites after a single injection of hyperpolarized [1‐13C]pyruvate. An optimal control optimized universal‐rotation pulse was used for refocusing to minimize signal loss caused by B1 imperfections. Non‐dw spectra were acquired interleaved with the dw spectra and these were used to correct for signal decay during the acquisition as a result of T1 decay, pulse imperfections, flow etc. The data showed that the ADC values for [1‐13C]lactate (0.4–0.7 µm2/ms) and [1‐13C]alanine (0.4–0.9 µm2/ms) were about a factor of two lower than the ADC of [1‐13C]pyruvate (1.1–1.5 µm2/ms). This indicates a more restricted diffusion space for the former two metabolites consistent with lactate and alanine being intracellular. The higher ADC for pyruvate (similar to the proton ADC) reflected that the injected substance was not confined inside the muscle cells but also present extracellular. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
13.
ObjectiveTo assess intervention feasibility and acceptability, and compare the effectiveness of the CHOICES Decision Aid (DA) versus the National Cancer Institute (NCI) Cancer Clinical Trials (CCT) website to improve knowledge about CCTs and preparedness to make an informed decision.MethodsOncology patients (n = 101) with a scheduled clinic visit were enrolled and randomized. Decision-making variables were collected at two timepoints. Post-intervention scores were examined via paired t-tests and multivariate regression analyses. Predictors of the magnitudes of the change in scores were examined in multivariable regression analyses.ResultsThe interventions were feasible to implement and acceptable to participants. Both interventions increased objective and subjective knowledge, improved clarity of opinions, and reduced decisional conflict (p-values < 0.01). Improvements in the belief that one could find out about CCTs were observed in the CHOICES DA arm (p < 0.001). Multivariable analyses controlling for educational attainment showed no significant differences in the magnitude of change in outcome variables between intervention arms, but did find that improvements in some variables in the NCI arm – but not CHOICES DA arm – were associated with previous educational attainment.ConclusionsInterventions were feasible to implement and acceptable. Improvements in knowledge and decision-making outcomes were observed in both arms, supporting the view that interventions to improve CCT decision making are effective and feasible. Our results suggest that the CHOICES DA may be more effective than an informational website in improving decision-making outcomes regardless of participants’ educational attainment.Practice implicationsCCT resources should support informed decision-making among all cancer survivors, regardless of educational attainment.  相似文献   
14.

Background/Objectives

Due to its rarity, epidermoid cyst in intrapancreatic accessory spleen (ECIPAS) is still a diagnostic dilemma during clinical practice. The aim of this review was to summarize the epidemiologic features and management of ECIPAS.

Methods

MEDLINE and EMBASE were searched for English articles reporting on ECIPAS up to April 30th, 2018 following the methodology suggested by the PRISMA guidelines. Categorical variables were reported as frequency and percentage. Continuous variables were reported as median (range).

Results

A total of 56 patients from 47 full articles were included for the final data synthesis. More than half of the ECIPASs (59%) were found incidentally. The female/male ratio was 1.33. ECIPAS is typically a single mono-/multi-lobular cystic lesions in the pancreatic tail with thickened cystic wall or various amount of solid component which had identical density/signal to the spleen on imaging examinations. The cyst is filled with serous or non-serous fluid. Recognition of the surrounding ectopic splenic tissue is the key point to diagnose ECIPAS. However, no preoperative examination was able to make a definite diagnosis. Almost all the patients (96%) received surgical treatment, due to the suspicion of pancreatic malignant or potentially malignant cystic tumor, especially mucinous cystic neoplasm (MCN).

Conclusions

Although seldom encountered, ECIPAS should be considered as a differential diagnosis for pancreatic cystic lesions, especially when solid component was detected. As a benign disease, unnecessary surgery should be avoided. Because it is difficult to make a definite diagnosis preoperatively by one single examination, multiple modalities may be required.  相似文献   
15.
模数转换器(Analog-to-Digital Converter,ADC)是片上集成系统的关键部件,通过对逐次逼近逻辑电路和三值逻辑原理的研究,提出了一种基于碳纳米场效应晶体管(Carbon Nanotube Field Effect Transistor,CNFET)的三值逐次逼近ADC设计方案。该方案首先控制三值电容阵列的底板电压,逐次逼近其模拟量值,产生由高位到低位的二值信号,然后由编码器将二值转换为三值信号,完成整个转换过程,最后实验证明了所设计的电路逻辑功能正确,并具有明显的高速、低功耗特性。  相似文献   
16.
PURPOSEImage-guided adaptive brachytherapy (IGABT) recently has shown excellent clinical outcomes with superior local control and less toxicity. For IGABT, T2W (T2-weighted) MRI is the gold standard. However, studies have shown that target delineation with the same results in uncertainties, poor interobserver variabilities, and low conformity indices for high-risk clinical target volume contours. In this study, we investigate the role of diffusion-weighted imaging–derived apparent diffusion coefficient (ADC) maps to aid in IGABT. We also evaluated ADC from the baseline to brachytherapy.Methods and MaterialsThirty selected patients were enrolled for this study, and two MRIs were taken at diagnosis and before brachytherapy. Patients were divided into two groups, Group 1 being patients with parametrial involvement before external beam radiotherapy and no parametrial involvement before brachytherapy. Group 2 included patients with parametrial involvement before external beam radiotherapy and persistent parametrial involvement before brachytherapy. ADC was measured at the center, edge, and 1 cm from the edge.ResultsThe measured ADC increased from diagnosis to brachytherapy, and this increase was more for the patients in Group 1 than in Group 2. The mean TDadc (diagnosis ADC, center), TEadc (tumor edge ADC diagnosis), and T1cmDadc (1 cm from edge at diagnosis) were 0.884, 1.45, and 1.9 × 10?3 mm2/s, respectively. The TBadc (ADC at brachytherapy, center), TEBadc (tumor edge ADC at brachytherapy), and TE1cmBadc (1 cm from edge brachytherapy) were 1.2, 1.8, and 2.3 × 10?3 mm2/s, respectively, p-value <0.00001. No abnormal ADC was present outside the high-risk clinical target volume contours.ConclusionMRI-based IGABT using T2W imaging essentially covers all functionally abnormal zones at brachytherapy. Diffusion-weighted imaging, along with ADC maps, should only be used as a supplement for target delineation.  相似文献   
17.

Objective

To review the strengths and weaknesses of deliberative and intuitive processes in the context of patient decision support and to discuss implications for decision aid (DA) design.

Methods

Conceptual review of the strengths and weaknesses of intuitive and analytical decision making and applying these findings to the practice of DA design.

Results

DAs combine several important goals: providing information, helping to clarify treatment related values, supporting preference construction processes, and facilitating more active engagement in decision making. Many DAs encourage patients to approach a decision analytically, without solid theoretical or empirical grounding for this approach. Existing research in other domains suggests that both intuition and deliberation may support decision making. We discuss implications for patient decision support and challenge researchers to determine when combining these processes leads to better outcomes.

Conclusions

Intuitive and analytical decision processes may have complementary effects in achieving the desired outcomes of patient decision support.

Practice implications

DA developers should be aware that tools solely targeted at supporting deliberation may limit DA effectiveness and harm preference construction processes. Patients may be better served by combined strategies that draw on the strengths and minimize the weaknesses of both deliberative and intuitive processes.  相似文献   
18.

Objective

This study sought to explore the perceived influence of narrative medicine training on clinical skill development of fourth-year medical students, focusing on competencies mandated by ACGME and the RCPSC in areas of communication, collaboration, and professionalism.

Methods

Using grounded-theory, three methods of data collection were used to query twelve medical students participating in a one-month narrative medicine elective regarding the process of training and the influence on clinical skills. Iterative thematic analysis and data triangulation occurred.

Results

Response rate was 91% (survey), 50% (focus group) and 25% (follow-up). Five major findings emerged. Students perceive that they: develop and improve specific communication skills; enhance their capacity to collaborate, empathize, and be patient-centered; develop personally and professionally through reflection. They report that the pedagogical approach used in narrative training is critical to its dividends but misunderstood and perceived as counter-culture.

Conclusion/Practice implications

Participating medical students reported that they perceived narrative medicine to be an important, effective, but counter-culture means of enhancing communication, collaboration, and professional development. The authors contend that these skills are integral to medical practice, consistent with core competencies mandated by the ACGME/RCPSC, and difficult to teach. Future research must explore sequelae of training on actual clinical performance.  相似文献   
19.
20.
阐述护士职业精神的概念与内涵,介绍国外护士职业精神测评工具研究现状,综合论述了护士职业精神的影响因素包括个人因素、组织因素和职业因素,并提出构建我国护士职业精神的理论体系和评价方式、倡导护士职业精神培育和营造健康的护理职业环境等建议,为发展我国护士职业精神理论和提高护士职业精神提供参考。  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