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   842篇
  免费   63篇
  国内免费   9篇
耳鼻咽喉   15篇
儿科学   26篇
妇产科学   10篇
基础医学   81篇
口腔科学   29篇
临床医学   92篇
内科学   155篇
皮肤病学   2篇
神经病学   38篇
特种医学   138篇
外科学   111篇
综合类   16篇
预防医学   121篇
眼科学   14篇
药学   42篇
肿瘤学   24篇
  2021年   18篇
  2020年   7篇
  2019年   8篇
  2018年   21篇
  2017年   7篇
  2016年   17篇
  2015年   16篇
  2014年   12篇
  2013年   46篇
  2012年   44篇
  2011年   37篇
  2010年   24篇
  2009年   29篇
  2008年   28篇
  2007年   37篇
  2006年   35篇
  2005年   22篇
  2004年   23篇
  2003年   40篇
  2002年   25篇
  2001年   27篇
  2000年   31篇
  1999年   30篇
  1998年   16篇
  1997年   7篇
  1996年   12篇
  1995年   6篇
  1994年   17篇
  1993年   11篇
  1992年   15篇
  1991年   6篇
  1990年   13篇
  1989年   16篇
  1988年   16篇
  1987年   12篇
  1986年   9篇
  1985年   16篇
  1984年   9篇
  1983年   6篇
  1981年   13篇
  1980年   7篇
  1978年   11篇
  1977年   7篇
  1975年   8篇
  1974年   6篇
  1972年   11篇
  1971年   8篇
  1969年   6篇
  1967年   8篇
  1966年   10篇
排序方式: 共有914条查询结果,搜索用时 15 毫秒
101.
PIX306 was a phase 3, randomised, single-blind, multicentre trial conducted in adult patients with diffuse large B-cell lymphoma (DLBCL) or follicular lymphoma (FL) grade 3 who relapsed after ≥1 rituximab-containing regimen and were not eligible for a stem cell transplant. Patients were randomised 1:1 to pixantrone 50 mg/m2 or gemcitabine 1000 mg/m2 on days 1, 8 and 15 of a 28-day cycle, combined with rituximab 375 mg/m2 on day 1, for up to six cycles. Patients were followed for up to 96 weeks. The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall survival (OS), complete response (CR) rate, overall response rate (ORR) and safety. Overall, 312 patients were randomised (median age 73·0 years). The study did not meet its primary endpoint. Median PFS [95% confidence interval (CI)] was 7·3 months (5·2–8·4) with pixantrone + rituximab (PIX + R) and 6·3 months (4·4–8·1) with gemcitabine + rituximab [GEM + R; hazard ratio (HR): 0·85; 95% CI 0·64–1·14; P = 0·28]. Median OS was 13·3 (10·1–19·8) months with PIX + R and 19·6 (12·4–31·9) months with GEM + R (HR: 1·13; 95% CI 0·83–1·53). ORR was 61·9% and 43·9% respectively and CR rate 35·5% and 21·7%. The incidence of adverse events, including cardiac events, was not statistically significant different between PIX + R and GEM + R.  相似文献   
102.
103.
104.
This study assessed the nutritional quality of snacks and beverages sold in vending machines. The contents of snack and beverage vending machines in 78 buildings on 11 US post-secondary education campuses were surveyed. Of the 2607 snack machine slots surveyed, the most common snacks vended were salty snacks (e.g., chips, pretzels) and sweets (i.e., candy and candy bars). The 1650 beverage machine slots assessed contained twice as many sugar-sweetened beverages as non-calorie-containing beverages. Only two institutions sold both milk and 100% juice in vending machines. The portion of snacks and beverages sold averaged more than 200 cal. Neither snacks nor beverages were nutrient dense. The majority of snacks were low in fiber and high in calories and fat and almost half were high in sugar. Most beverages were high in calories and sugar. This study's findings suggest that vending machines provide limited healthful choices. Findings from benchmark assessments of components of the food environment, like the vending options reported here, can provide valuable input to campus administrators, health services, food service, and students who want to establish campus policies to promote healthful eating.  相似文献   
105.
Young adults frequently use restrictive eating (i.e., going for long periods [?8h] without eating to influence their shape or weight) to control their weight. The purpose of this study was to determine the prevalence of restrictive eating in young adults, compare eating behaviors of restrictive and non-restrictive eaters, and predict restrictive eaters. A diverse (56% white, 63% female) sample of young adults (n=2449) completed an online survey that included eating behavior scales (Restraint, Eating, Shape, and Weight Concerns, and Inappropriate Compensatory Behaviors from the Eating Disorder Examination-Questionnaire, Emotional and Disinhibited Eating from the Three-Factor Eating Questionnaire, and Night Eating from the Night Eating Questionnaire) and demographics. A quarter of women and 20% of men were classified as restrictive eaters. Independent t-tests revealed restrictive eaters had significantly (p<0.001) higher BMIs than non-restrictive eaters. Restrictive eaters also had significantly higher scores on all eating behavior scales than non-restrictive eaters even after controlling for potential confounding factors (BMI, race). Stepwise binary logistic regression revealed that increased eating, shape, and weight concerns, higher BMI, endorsement of inappropriate compensatory behaviors and night eating, being female, and white increased the odds of participants being restrictive eaters. This study can help healthcare professionals become more aware of weight control practices of young adults and create appropriate interventions.  相似文献   
106.
107.
This workshop was held a year after the initial positron emission tomography/magnetic resonance (PET/MR) workshop in Tübingen, which was recently reported in this journal. The discussions at the 2013 workshop, however, differed substantially from those of the initial workshop, attesting to the progress of combined PET/MR as an innovative imaging modality. Discussions were focused on the search for truly novel, unique clinical and research applications as well as technical issues such as reliable and accurate approaches for attenuation and scatter correction of PET emission data. The workshop provided hands-on experience with PET and MR imaging. In addition, structured and moderated open discussion sessions, including six dialogue boards and two roundtable discussions, provided input from current and future PET/MR imaging users. This summary provides a snapshot of the current achievements and challenges for PET/MR.  相似文献   
108.
AIMS: To evaluate the pre-clinical feasibility of real-time magnetic resonance imaging (rtMRI) to guide stent-graft placement for experimental aortic dissection (AD) and to alleviate disadvantages of ionising radiation and nephrotoxic contrast media. Endovascular stent-graft placement for thoracic aortic disease is usually performed under X-ray guidance. The feasibility of rtMRI-guided stent-graft placement is currently not known. METHODS AND RESULTS: By using a catheter-based technique, dissections of the descending thoracic aorta were successfully created in eight domestic pigs. Subsequent implantation of commercially available, nitinol-based stent-grafts was performed entirely under rtMRI guidance. By pre-interventional MRI, the mean minimal true-lumen diameter was 0.9 (0.825-0.975) cm. rtMRI permitted not only the successful and safe device navigation within the true lumen from the iliac arteries to the thoracic aorta, but also the precise positioning and deployment of the stent-graft and safe withdrawal of the delivery catheter in seven of eight pigs. This was achieved without any other complications. After the stent-graft placement, MRI demonstrated complete obliteration of the false lumen, which was confirmed at autopsy. All stent-grafts were well expanded resulting in an increase in the size of the true-lumen diameter to 2.05 (1.925-2.1) cm (P=0.066 vs. baseline). CONCLUSION: In experimental AD, rtMRI-guided endovascular stent-graft placement is feasible and safe and has the potential for mitigating radiation and contrast-related side effects. Additionally, it allows not only pre-interventional diagnosis and detailed anatomic diagnosis, but also permits immediate post-interventional, anatomical, and functional delineation of procedure success that may serve as a baseline for future comparison during follow-up.  相似文献   
109.
We have previously described a unique type of delta beta-thalassemia in a Chinese family characterized by increased expression of the G gamma and A gamma fetal globin genes in the absence of a large deletion in the beta-globlin gene cluster. Our earlier study of the beta-globin gene on this delta beta-thalassemia chromosome showed a promoter mutation in the TATA box. In this report, we describe the results of our study of the fetal globin domain of this delta beta-thalassemia chromosome. We have cloned a 13-kb DNA fragment that includes the G gamma and the A gamma genes and the 3' A gamma enhancer element of this delta beta-thalassemia chromosome. DNA sequence analysis of the G gamma and A gamma-globin genes including their promoters did not show any mutations, but analysis of the putative enhancer element downstream from the A gamma-globin gene showed a C to T substitution 2,401 nucleotides downstream from the A gamma cap site. We performed DNA linkage analysis to determine if this mutation is unique to this chromosome or represents a common polymorphism. Our linkage analysis showed that this mutation is not a common polymorphism and that it is also not an intrinsic part of the haplotype of the chromosome on which it was found. We also studied the interaction of nuclear proteins from erythroid and nonerythroid cells with the DNA sequences surrounding this mutation. We have shown by in vitro DNase I footprinting that this mutation falls within a region that is occupied by a novel DNA-binding protein that binds to this site in nuclear extracts from erythroid, but not nonerythroid cells. The binding of this nuclear protein to DNA appears to be dependent on GATA-1 binding to an adjacent GATA-1 site. We have also developed a new functional assay to compare the activity of the normal and mutant A gamma enhancer elements in erythroid cells. Analysis of the activity of the mutant enhancer shows that the mutation completely eliminates all enhancer activity in this assay. These findings suggest that this mutation of the A gamma enhancer on a chromosome that carries a partially inactivated beta-globin gene may be responsible for the increased expression of both gamma-globin genes seen in this condition.  相似文献   
110.
OBJECTIVE: To examine the benefits and problems of a chronic fatigue syndrome (CFS) and fibromyalgia (FM) support organization as reported by its participants. METHODS: Active members (n = 32) and inactive members or dropouts (n = 135) of a regional support organization for people with CFS and FM completed a 26 item questionnaire by telephone interview or by self-completion and postal return. RESULTS: The most frequently endorsed benefits of membership were illness legitimization (67.8%), finding out helpful new information (66.4%), and feeling understood by others (62.2%). Lower frequency endorsements were given to: helped to find (35.0%) or deal with (38.5%) doctors, and helped to improve my illness (36.4%). The most frequently reported reasons for dropping out were inconvenient location (37.8%) or time (37.0%), too much negative talk or complaining (33.3%), too sick to attend (28.8%), and illness or coping improvement (29.6% each). The active-member group showed significantly higher (p < 0.04) symptom severity scores and less illness improvement (p < 0.01) in comparison to the inactive/dropout group. CONCLUSION: This cross-sectional study suggests that support groups for CFS are viewed as helpful by participants on a number of illness related issues. On the other hand, active members reported greater symptom severity and less illness improvement than inactive members or dropouts.  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