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   3041篇
  免费   168篇
  国内免费   15篇
耳鼻咽喉   24篇
儿科学   42篇
妇产科学   48篇
基础医学   492篇
口腔科学   63篇
临床医学   276篇
内科学   588篇
皮肤病学   97篇
神经病学   308篇
特种医学   183篇
外科学   444篇
综合类   18篇
一般理论   2篇
预防医学   142篇
眼科学   40篇
药学   239篇
中国医学   18篇
肿瘤学   200篇
  2023年   30篇
  2022年   41篇
  2021年   64篇
  2020年   45篇
  2019年   56篇
  2018年   67篇
  2017年   50篇
  2016年   54篇
  2015年   83篇
  2014年   114篇
  2013年   140篇
  2012年   214篇
  2011年   263篇
  2010年   150篇
  2009年   157篇
  2008年   241篇
  2007年   199篇
  2006年   182篇
  2005年   188篇
  2004年   159篇
  2003年   170篇
  2002年   149篇
  2001年   41篇
  2000年   28篇
  1999年   33篇
  1998年   28篇
  1997年   25篇
  1996年   19篇
  1995年   13篇
  1994年   17篇
  1993年   12篇
  1992年   17篇
  1991年   19篇
  1990年   16篇
  1989年   14篇
  1988年   15篇
  1987年   13篇
  1986年   15篇
  1985年   11篇
  1984年   7篇
  1983年   17篇
  1981年   6篇
  1979年   4篇
  1978年   5篇
  1977年   3篇
  1973年   2篇
  1971年   3篇
  1970年   2篇
  1969年   2篇
  1968年   2篇
排序方式: 共有3224条查询结果,搜索用时 15 毫秒
131.
132.
Recent studies indicate that the primary somatosensory cortex (S1) is active not only when touch is physically perceived but also when it is merely observed to be experienced by another person. This social responsivity of S1 has important implications for our understanding of S1 functioning. However, S1 activity during touch observation has not been characterized in great detail to date. We focused on two features of the S1 functional architecture during touch observation, namely the topographical arrangement of index and middle finger receptive fields (RFs), and their dynamic shrinkage during concurrent activation. Both features have important implications for human behavior. We conducted two fMRI studies at 7 T, one where touch was physically perceived, and one where touch was observed. In the two experiments, participants either had their index finger and/or middle finger stimulated using paintbrushes, or just observed similar touch events on video. Our data show that observing and physically experiencing touch elicits overlapping activity changes in S1. In addition, observing touch to the index finger or the middle finger alone evoked topographically arranged activation foci in S1. Importantly, when co-activated, the index and middle finger RFs not only shrank during physical touch perception, but also during touch observation. Our data, therefore, indicate a similarity between the functional architecture of S1 during touch observation and physical touch perception with respect to single-digit topography and RF shrinkage. These results may allow the tentative conclusion that even primary somatosensory experiences, such as physical touch perception, can be shared amongst individuals.  相似文献   
133.
Unselected data of nationwide studies of hospitalized patients with COVID-19 are still sparse, but these data are of outstanding interest to avoid exceeding hospital capacities and overloading national healthcare systems. Thus, we sought to analyze seasonal/regional trends, predictors of in-hospital case-fatality, and mechanical ventilation (MV) in patients with COVID-19 in Germany. We used the German nationwide inpatient samples to analyze all hospitalized patients with a confirmed COVID-19 diagnosis in Germany between 1 January and 31 December in 2020. We analyzed data of 176,137 hospitalizations of patients with confirmed COVID-19-infection. Among those, 31,607 (17.9%) died, whereby in-hospital case-fatality grew exponentially with age. Overall, age ≥ 70 years (OR 5.91, 95%CI 5.70–6.13, p < 0.001), pneumonia (OR 4.58, 95%CI 4.42–4.74, p < 0.001) and acute respiratory distress syndrome (OR 8.51, 95%CI 8.12–8.92, p < 0.001) were strong predictors of in-hospital death. Most COVID-19 patients were treated in hospitals in urban areas (n = 92,971) associated with the lowest case-fatality (17.5%), as compared to hospitals in suburban (18.3%) or rural areas (18.8%). MV demand was highest in November/December 2020 (32.3%, 20.3%) in patients between the 6th and 8th age decade. In the first age decade, 78 of 1861 children (4.2%) with COVID-19-infection were treated with MV, and five of them died (0.3%). The results of our study indicate seasonal and regional variations concerning the number of COVID-19 patients, necessity of MV, and case fatality in Germany. These findings may help to ensure the flexible allocation of intensive care (human) resources, which is essential for managing enormous societal challenges worldwide to avoid overloaded regional healthcare systems.  相似文献   
134.
Objectives: We sought to determine the effects of experience on the Mitraclip® procedure steps as well as procedure safety and functional results. Background: MR has proven deleterious in heart failure. Mitraclip® therapy evolved an important option in patients with severely reduced left ventricular function (LVEF). Methods: Between 2011 and 2016, 126 consecutive patients were grouped in three groups and investigated in a prospective observational study. We evaluated the duration of procedural steps, safety endpoints, and functional results. Results: The median logistic EuroScore was 32% (7–40%). Ninety‐five percent of patients were in NYHA‐stage ≥III and 51% had a LVEF <30%. Groups were homogeneous as to their baseline NYHA status and right heart catheterization data. Echocardiography data are comparable, albeit with a decreasing effective regurgitant orifice area (0.44 ± 0.21 group I vs. 0.34 ± 0.22 group III, P = 0.02). Frailty was less frequent and baseline 6 min walking test results improved from group I to group III. Duration of a first clip placement decreased from 106 ± 50 to 50 ± 21 min (P < 0.001). Total procedure time decreased from 221 ± 70 to 144 ± 68 (P < 0.001). The number of clips implanted increased from 66 to 79 (P = 0.02). MitraClip® implantation was effective in either group but the combined safety endpoint was reached less frequent in group III (P = 0.01). There was no difference in MACCE rate, 30 day‐ or intrahospital‐mortality between groups. Conclusion: Safety and duration of procedure steps improved substantially with experience. MR reduction was sustained from the beginning without further improvement. Patient selection is a key factor for success. © 2016 Wiley Periodicals, Inc.  相似文献   
135.

Objectives

The aim of this study was to assess the safety and effectiveness of a next-generation low-dose drug-coated balloon (DCB) designed to optimize the amount of drug transferred into the vessel wall and to maximize the amount of time the drug resides in the vessel wall.

Background

Several randomized controlled studies evaluating various DCBs have demonstrated a significantly higher patency rate compared with noncoated percutaneous transluminal angioplasty balloons at 1 year. However, the data are limited and vary by DCB at longer follow-up time points. An earlier generation low-dose DCB failed to demonstrate significant treatment effect at 2 years, raising questions regarding the durability of low-dose DCBs.

Methods

In this prospective, multicenter trial, 294 patients were randomized (3:1) to treatment with a DCB or an uncoated percutaneous transluminal angioplasty balloon. Assessments at 2 years included primary patency with duplex ultrasonography, clinically driven target lesion revascularization, and functional outcomes.

Results

Primary patency at 2 years was significantly higher in the DCB cohort (75.9% vs. 61.0%; p = 0.025), and the rate of clinically driven target lesion revascularization was significantly lower (12.1% vs. 30.5%; p < 0.001). There were no major limb amputations in either group. The rates of all-cause (6.5% vs. 5.1%; p = 1.00) and cardiovascular-related (1.6% vs. 1.7%; p = 1.00) mortality were similar between groups. Functional improvements over baseline were sustained in both groups, with 60% fewer reinterventions in the DCB group.

Conclusions

A sustained treatment effect is achievable with a low-dose DCB with an optimized coating formulation. This trial demonstrated for the first time a statistically significantly higher primary patency rate for a low-dose DCB versus PTA at 2 years. (CVI Drug Coated Balloon European Randomized Clinical Trial; NCT01858363)  相似文献   
136.
BackgroundAntimicrobial resistance poses a risk for healthcare, both in the community and hospitals. The spread of multidrug-resistant organisms (MDROs) occurs mostly on a local and regional level, following movement of patients, but also occurs across national borders.AimThe aim of this observational study was to determine the prevalence of MDROs in a European cross-border region to understand differences and improve infection prevention based on real-time routine data and workflows.MethodsBetween September 2017 and June 2018, 23 hospitals in the Dutch (NL)–German (DE) cross-border region (BR) participated in the study. During 8 consecutive weeks, patients were screened upon admission to intensive care units (ICUs) for nasal carriage of meticillin-resistant Staphylococcus aureus (MRSA) and rectal carriage of vancomycin-resistant Enterococcus faecium/E. faecalis (VRE), third-generation cephalosporin-resistant Enterobacteriaceae (3GCRE) and carbapenem-resistant Enterobacteriaceae (CRE). All samples were processed in the associated laboratories.ResultsA total of 3,365 patients were screened (median age: 68 years (IQR: 57–77); male/female ratio: 59.7/40.3; NL-BR: n = 1,202; DE-BR: n = 2,163). Median screening compliance was 60.4% (NL-BR: 56.9%; DE-BR: 62.9%). MDRO prevalence was higher in DE-BR than in NL-BR, namely 1.7% vs 0.6% for MRSA (p = 0.006), 2.7% vs 0.1% for VRE (p < 0.001) and 6.6% vs 3.6% for 3GCRE (p < 0.001), whereas CRE prevalence was comparable (0.2% in DE-BR vs 0.0% in NL-BR ICUs).ConclusionsThis first prospective multicentre screening study in a European cross-border region shows high heterogenicity in MDRO carriage prevalence in NL-BR and DE-BR ICUs. This indicates that the prevalence is probably influenced by the different healthcare structures.  相似文献   
137.
Binary polymer blends were separated by liquid chromatography at the critical point of adsorption. By operating at chromatographic conditions corresponding to the critical point of one blend component, the blends were separated regardless of the molar mass distributions of the components. After the separation step both components were precisely detected by an on-line capillary viscometer. In contrast to refractive index detection, where a strong solvent peak appears in most cases, the viscosity signal is not affected by sight deviations in the mobile phase composition. Under critical conditions of adsorption of one component both blend components exhibit normal Mark-Houwink behaviour. Therefore, the viscosity detector in conjunction with a concentration detector can be used for determining the molar mass distribution of both blend components.  相似文献   
138.
Minerals fulfil a wide variety of functions in the optimal functioning of the immune system. This review reports on the minerals that are essential for the immune system’s function and inflammation regulation. We also discuss nutritional aspects of optimized mineral supply. The supply of minerals is important for the optimal function of the innate immune system as well as for components of adaptive immune defense; this involves defense mechanisms against pathogens in addition to the long-term balance of pro- and anti-inflammatory regulation. Generally, a balanced diet is sufficient to supply the required balance of minerals to help support the immune system. Although a mineral deficiency is rare, there are nevertheless at-risk groups who should pay attention to ensure they are receiving a sufficient supply of minerals such as magnesium, zinc, copper, iron, and selenium. A deficiency in any of these minerals could temporarily reduce immune competence, or even disrupt systemic inflammation regulation in the long term. Therefore, knowledge of the mechanisms and supply of these minerals is important. In exceptional cases, a deficiency should be compensated by supplementation; however, supplement over-consumption may be negative to the immune system, and should be avoided. Accordingly, any supplementation should be medically clarified and should only be administered in prescribed concentrations.  相似文献   
139.
Psychotherapie Forum -  相似文献   
140.
AIDS and Behavior - Little is known about the intersection of HIV stigma and substance use stigma. Using data from 188 HIV-positive people who inject drugs (PWID) in Russia, we examined the...  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