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   2118篇
  免费   112篇
  国内免费   6篇
耳鼻咽喉   24篇
儿科学   18篇
妇产科学   94篇
基础医学   319篇
口腔科学   15篇
临床医学   198篇
内科学   341篇
皮肤病学   22篇
神经病学   223篇
特种医学   103篇
外科学   298篇
综合类   9篇
一般理论   2篇
预防医学   86篇
眼科学   139篇
药学   115篇
中国医学   8篇
肿瘤学   222篇
  2023年   21篇
  2022年   38篇
  2021年   41篇
  2020年   34篇
  2019年   39篇
  2018年   45篇
  2017年   27篇
  2016年   53篇
  2015年   51篇
  2014年   82篇
  2013年   104篇
  2012年   130篇
  2011年   151篇
  2010年   96篇
  2009年   100篇
  2008年   153篇
  2007年   144篇
  2006年   136篇
  2005年   158篇
  2004年   135篇
  2003年   146篇
  2002年   132篇
  2001年   31篇
  2000年   17篇
  1999年   24篇
  1998年   17篇
  1997年   22篇
  1996年   15篇
  1995年   12篇
  1994年   11篇
  1993年   6篇
  1992年   12篇
  1991年   8篇
  1990年   4篇
  1989年   3篇
  1988年   2篇
  1984年   3篇
  1983年   3篇
  1982年   7篇
  1981年   4篇
  1980年   1篇
  1979年   1篇
  1978年   2篇
  1977年   3篇
  1975年   2篇
  1974年   2篇
  1972年   1篇
  1969年   2篇
  1966年   1篇
  1926年   1篇
排序方式: 共有2236条查询结果,搜索用时 20 毫秒
31.
32.
Introduction: Featuring demyelination and axonal degeneration, multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system representing a prominent cause of disability in young adults. The recently established therapeutic targeting of B cells in MS patients using CD20 monoclonal antibodies (CD20-mAbs) not only profoundly suppresses inflammatory disease activity but also materializes as the first treatment approach against disability accumulation in a subset of patients with primary progressive MS.

Areas covered: We will review current concepts regarding the immunopathology of B cells as well as results of clinical trials with CD20-mAbs in MS, from the murine-human chimeras rituximab and ublituximab to their increasingly humanized counterparts ocrelizumab and ofatumumab. We conducted a literature search using PubMed, clinicaltrials.gov, and clinicaltrialsregister.eu. We will focus on studies emphasizing the effectiveness of these mAbs in reducing MS disease activity and progression, long-term safety, optimal dosage and maintenance regimens. Lastly, we will turn to outstanding questions regarding anti-CD20 therapy in MS.

Expert opinion: CD20-mAbs could become first-line drugs in selected patients with highly active MS and already constitute an option for PPMS. Future studies could evaluate whether administration regimens currently in use can be optimized, while registry data could shed light on risk versus benefits on the long run, considering immunosenescence and a potentially increased risk of malignancies and infections in an aging population.  相似文献   

33.
Although acetylsalicylic acid (ASA, aspirin) reduces the risk of ischemic events in patients with atherosclerosis, a substantial number of incidents continue to occur. As only limited data exist we evaluated the antiplatelet effectiveness of ASA in patients with different manifestations of atherosclerosis as in cerebrovascular, coronary artery and peripheral arterial disease (CVD, CAD, PAD). For the evaluation of the antiplatelet effectiveness of ASA we used whole blood aggregometry (Chrono-log Model 590). The patients in the different subgroups received ASA 100, 200 or 500 mg daily. We analysed 737 consecutive patients: 47.5 % with CVD, 33.6 % with CAD, and 18.9 % with PAD. We identified 28.0 % of the CVD, 18.1 % of the CAD and 21.6 % of the PAD patients to be ASA low-responder (ALR). Comparing subgroups treated with 100 mg ASA, 36.4 % were ALR in the CVD group as were 13.1 % of the CAD and 21.6 % of the PAD patients. Multivariate regression analysis revealed an odds ratio for being ALR of 4.50 (95 % confidence interval (CI) 1.70–11.9) when 100 mg and of 2.97 (95 % CI 1.58–5.60) when 200 mg ASA was taken compared to a dose of 500 mg. Despite the proven benefits of antiplatelet therapy in the secondary prevention of atherosclerotic disease, current antiplatelet management is suboptimal as up to 36 % of patients failed to achieve an adequate platelet inhibitory effect. Our findings may explain, at least in part, the high rates of cardiovascular events observed in the course of atherothrombotic disease and support the need to improve antiplatelet therapy.  相似文献   
34.
35.
Data from farmer-managed fields have not been used previously to disentangle the impacts of daily minimum and maximum temperatures and solar radiation on rice yields in tropical/subtropical Asia. We used a multiple regression model to analyze data from 227 intensively managed irrigated rice farms in six important rice-producing countries. The farm-level detail, observed over multiple growing seasons, enabled us to construct farm-specific weather variables, control for unobserved factors that either were unique to each farm but did not vary over time or were common to all farms at a given site but varied by season and year, and obtain more precise estimates by including farm- and site-specific economic variables. Temperature and radiation had statistically significant impacts during both the vegetative and ripening phases of the rice plant. Higher minimum temperature reduced yield, whereas higher maximum temperature raised it; radiation impact varied by growth phase. Combined, these effects imply that yield at most sites would have grown more rapidly during the high-yielding season but less rapidly during the low-yielding season if observed temperature and radiation trends at the end of the 20th century had not occurred, with temperature trends being more influential. Looking ahead, they imply a net negative impact on yield from moderate warming in coming decades. Beyond that, the impact would likely become more negative, because prior research indicates that the impact of maximum temperature becomes negative at higher levels. Diurnal temperature variation must be considered when investigating the impacts of climate change on irrigated rice in Asia.  相似文献   
36.
25-Hydroxyvitamin D3-1 alpha-hydroxylase (25(OH)D3-1 alpha-hydroxylase), the key enzyme of 1 alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3) production, is expressed in monocyte-derived macrophages (MACs). Here we show for the first time constitutive expression of 25(OH)D3-1 alpha-hydroxylase in monocyte-derived dendritic cells (DCs), which was increased after stimulation with lipopolysaccharide (LPS). Accordingly, DCs showed low constitutive production of 1,25(OH)2D3, but activation by LPS increased 1,25(OH)2D3 synthesis. In addition, 25(OH)D3-1 alpha-hydroxylase expression was found in blood DCs but not in CD34+-derived DCs. Next we analyzed the functional consequences of these results. Addition of 1,25(OH)2D3 at concentrations comparable with those produced by DCs inhibited the allostimulatory potential of DCs during the early phase of DC differentiation. However, terminal differentiation decreased the responsiveness of DCs to 1,25(OH)2D3. In conclusion, DCs are able to produce 1,25(OH)2D3 especially following stimulation with LPS. Terminal maturation renders DCs unresponsive to the effects of 1,25(OH)2D3, but those cells are able to suppress the differentiation of their own precursor cells in a paracrine way through the production of 1,25(OH)2D3.  相似文献   
37.
BACKGROUND: This study sought to evaluate safety and radiation exposure when using intracardiac echocardiography (ICE) in comparison to transesophageal echocardiography (TEE) in order to guide transcatheter closure of interatrial communications. METHODS: Eighty patients (44 males, 36 females, mean age 46, SD 13 years) undergoing device closure of atrial septal defect (n=12) or patent foramen ovale (n=68) had the procedure guided by ICE (n=50, group 1) or TEE (n=30, group 2). In group 1, all procedural stages were completely guided by ICE, including imaging of the interatrial communication during balloon sizing, device unfolding and release, and during the final check for adequate positioning. In group 2, exclusive implantation of devices was guided by use of TEE. RESULTS: Especially, the spatial relationship between device and cardiac structures (e.g. the ascending aorta, the interatrial septum and the superior vena cava) was accurately demonstrated in group 1. Image resolution provided by ICE was superior to that of TEE. No severe complications, including any related to ICE, were seen. Fluoroscopy time (FT) and procedure time (PT) were shorter in group 1 than in group 2 (FT: 5.5+/-1.5 min vs. 9.3+/-1.6 min, P<0.0001; PT: 31.9+/-4.6 min vs. 38.8+/-5.8 min, P<0.01). Neither sedation nor anesthesia was required in group 1. CONCLUSIONS: ICE is a safe tool to guide device closure of interatrial communications. For the patient, procedural stress and radiation exposure are negligible. ICE can be considered the guiding tool of choice for device closure, particularly when long or repeated echocardiographic viewing is required.  相似文献   
38.
Circadian rhythms in glucose metabolism are well documented. Most studies, however, evaluated such variations under conditions of continuous glucose supply, either via food intake or glucose infusion. Here we assessed in 30 subjects circadian variations in concentrations of plasma glucose, serum insulin, and C-peptide during a 72-hour fasting period to evaluate rhythms independent from glucose supply. Furthermore we assessed differences in these parameters between normal-weight (n = 20) and overweight (n = 10) subjects. Blood was sampled every 4 hours. During fasting, plasma glucose, serum insulin, and C-peptide levels gradually decreased (all P < .001). While there was no circadian variation in plasma glucose levels after the first day of fasting, serum levels of insulin were constantly higher in the morning (8.00 h) than at night (0.00 h) (P < .001), although the extent of this morning-associated rise in insulin levels decreased with the time spent fasting (P = .001). Also, morning C-peptide concentrations were higher compared to the preceding night (P < .001). The C-peptide/insulin ratio (CIR) decreased during prolonged fasting (P = .030), suggesting a decrease in hepatic insulin clearance. Moreover, CIR was significantly lower in the morning than at the night of day 1 and day 2 of fasting (P = .010 and P = .004, respectively). Compared to normal-weight subjects, overweight subjects had higher plasma glucose, as well as serum insulin and C-peptide levels (all P < .03). Data indicate preserved circadian rhythms in insulin concentrations in the presence of substantially decreased glucose levels in normal-weight and overweight subjects. This finding suggests a central nervous system contribution to the regulation of insulin secretion independent of plasma glucose levels.  相似文献   
39.

Background

In New Zealand the Accident Compensation Corporation (ACC) is a state-funded insurance agency that accepts claims for accidental injuries, including lumbar spine injuries. It is unknown whether ACC claim status (accepted, not accepted) affects low back pain (LBP) outcomes, or whether benefit status (e.g., sickness, disability) further affects outcomes in patients without ACC cover

Aims

This study aimed to determine whether ACC claim and benefit status are likely to influence a range of outcomes for people with LBP in New Zealand.

Methods

A prospective survey of low back pain patients was performed (April 2008–October 2010). ACC claim status was recorded, and individuals without accepted claims indicated benefit status. Surveys were sent at multiple time points; pain, functional limitation, psychological factors, and general health were assessed. Statistical analysis was undertaken using ANCOVA and ANOVA (p<0.05).

Results

In total, 168 patients completed the study. Six-month measures showed individuals with no ACC claim for LBP to overall have poorer outcomes (mental health, p=0.039; pain, p=0.045; functional limitation, p=0.049); sub-group analysis (no ACC claim) between those with or without a benefit showed those on benefits to have significantly higher functional limitation (p<0.001), poorer physical health (p=0.002), greater pain (p=0.027), and stronger fear avoidance behaviours for both work (p=0.047) and physical activity (p=0.35).

Conclusion

Findings indicate individuals with accepted ACC claims for LBP have significantly better outcomes than those without, and patients on benefits with no accepted ACC claim for LBP have even poorer outcomes.  相似文献   
40.
Nearly all countries in the world today are burdened with malnutrition, manifesting as undernutrition, micronutrient deficiencies, and/or overweight and obesity. Despite some progress, efforts to alleviate malnutrition are hampered by a shortage in number, skills, and geographic coverage, of a workforce for nutrition. Here, we report the findings of the Castel Gandolfo workshop, a convening of experts from diverse fields in March 2014 to consider how to develop the capacity of a global cadre of nutrition professionals for the post-2015 development era. Workshop participants identified several requirements for developing a workforce for nutrition, including an ability to work as part of a multisectoral team; communication, advocacy, and leadership skills to engage decision makers; and a set of technical skills to address future challenges for nutrition. Other opportunities were highlighted that could immediately contribute to capacity development, including the creation of a consortium to link global North and South universities, online training modules for middle managers, and practical, hands-on experiences for frontline nutrition workers. Institutional and organizational support is needed to enable workshop recommendations on education and training to be effectively implemented and sustained. The findings from the Castel Gandolfo workshop can contribute to the delivery of successful nutrition-relevant actions in the face of mounting external pressures and informing and attaining the forthcoming Sustainable Development Goals.  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