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   1464篇
  免费   66篇
  国内免费   32篇
耳鼻咽喉   43篇
儿科学   74篇
妇产科学   31篇
基础医学   194篇
口腔科学   20篇
临床医学   88篇
内科学   355篇
皮肤病学   24篇
神经病学   170篇
特种医学   15篇
外科学   69篇
综合类   16篇
预防医学   112篇
眼科学   63篇
药学   203篇
中国医学   2篇
肿瘤学   83篇
  2023年   3篇
  2022年   25篇
  2021年   23篇
  2020年   19篇
  2019年   22篇
  2018年   24篇
  2017年   18篇
  2016年   32篇
  2015年   39篇
  2014年   46篇
  2013年   75篇
  2012年   101篇
  2011年   111篇
  2010年   61篇
  2009年   49篇
  2008年   89篇
  2007年   100篇
  2006年   117篇
  2005年   123篇
  2004年   123篇
  2003年   106篇
  2002年   106篇
  2001年   5篇
  2000年   3篇
  1999年   13篇
  1998年   15篇
  1997年   9篇
  1996年   10篇
  1995年   11篇
  1994年   5篇
  1993年   8篇
  1992年   4篇
  1991年   5篇
  1990年   6篇
  1989年   2篇
  1988年   6篇
  1986年   4篇
  1985年   6篇
  1984年   3篇
  1983年   6篇
  1979年   2篇
  1978年   2篇
  1977年   3篇
  1976年   3篇
  1975年   2篇
  1974年   4篇
  1973年   2篇
  1965年   2篇
  1962年   1篇
  1961年   2篇
排序方式: 共有1562条查询结果,搜索用时 15 毫秒
31.
32.
Background: While converging evidence has led to the view that people with aphasia exploit compositional procedures when producing compound words, the issue of what compound‐internal characteristics are at play during these procedures is still under debate. It has been argued that constituent position and/or morphosyntactic prominence, i.e., being the head constituent of a compound, may influence the manner in which compounds are accessed. However, findings obtained from patient performances are thus far inconclusive, because positional and headedness effects are frequently confounded in a language.

Aims: In order to disentangle position‐in‐the‐string and headedness effects in compound production in aphasia, the main objective of this study is to investigate the performance of bilingual patients speaking languages in which these effects can be teased apart. Our secondary goal is to probe the roles of grammatical category (adjectives vs nouns) and of between‐language phonological similarity, as both these factors have been demonstrated to influence compound processing.

Methods & Procedures: Three English–French bilingual persons with aphasia participated in the study. Three experimental tasks, reading, repetition, and translation of isolated compound words, were administrated in each language. We contrasted French and English compounds that differ in the position of the head constituent: left for French and right for English.

Outcomes & Results: Two participants showed a similar pattern—a significantly reduced number of errors for the head (or first) constituent as compared to the non‐head (or second) constituent in French and an equivalent number of errors for both constituents in English—pointing to the cumulative effects of headedness and first‐position‐in‐the‐string in French, and to the mutual cancelling out of these effects in English. The third participant exhibited a non‐head constituent advantage in both languages, indicating that semantic modification of the head constituent by the non‐head constituent plays a prominent role in her accessing procedures. For all three participants phonological similarity influenced production, while grammatical category did not.

Conclusions: Our results reveal that headedness and position interact in the processing of compounds. They also demonstrate that compound constituents are processed asymmetrically across and within languages, thus confirming that people with aphasia are sensitive to compound‐internal structure. Moreover, they show that patients rely on varying structural information when accessing compounds.  相似文献   
33.
Toll-like receptor ligands (TLRLs) produced by various pathogens activate mitogen-activated protein kinases (MAPKs). While the dependence on p38 MAPK activation for the induction of inflammatory genes by the TLR4L, lipopolysaccharide (LPS), has been well documented, the importance of the p38 pathway in gene regulation by other TLRLs is less well understood. We have focused our analysis on two TLRLs with therapeutic potential, imidazoquinoline S28463 (TLR7L) and CpG DNA (TLR9L), to explore in detail their effects on the regulation of gene expression in macrophages. Here we report that activation of the p38 MAPK/MK2 pathway is crucial for both S28463- and CpG-induced cytokine and chemokine production. We show that the stability of TNF mRNA induced by CpG DNA and S28463 is not dependent on the p38 MAPK/MK2 pathway, in contrast to LPS-induced TNF mRNA. Using a GFP reporter construct under the control of the 3' untranslated region of the TNF gene, we demonstrate that S28463 and CpG DNA-induced MK2 signalling regulates TNF mRNA primarily at the translational level, whereas LPS-induced MK2 signalling regulates both the stability and translational efficiency of TNF mRNA. Overall, these data provide insight into distinct molecular mechanisms of gene expression regulation by different Toll-like receptor ligands.  相似文献   
34.
In the present work, for the first time, free vibration response of angle ply laminates with uncertainties is attempted using Multivariate Adaptive Regression Spline (MARS), Artificial Neural Network-Particle Swarm Optimization (ANN-PSO), Gaussian Process Regression (GPR), and Adaptive Network Fuzzy Inference System (ANFIS). The present approach employed 2D C0 stochastic finite element (FE) model based on the Third Order Shear Deformation Theory (TSDT) in conjunction with MARS, ANN-PSO, GPR, and ANFIS. The TSDT model used eliminates the requirement of shear correction factor owing to the consideration of the actual parabolic distribution of transverse shear stress. Zero transverse shear stress at the top and bottom of the plate is enforced to compute higher-order unknowns. C0 FE model makes it commercially viable. Stochastic FE analysis done with Monte Carlo Simulation (MCS) FORTRAN inhouse code, selection of design points using a random variable framework, and soft computing with MARS, ANN-PSO, GPR, and ANFIS is implemented using MATLAB in-house code. Following the random variable frame, design points were selected from the input data generated through Monte Carlo Simulation. A total of four-mode shapes are analyzed in the present study. The comparison study was done to compare present work with results in the literature and they were found in good agreement. The stochastic parameters are Young’s elastic modulus, shear modulus, and the Poisson ratio. Lognormal distribution of properties is assumed in the present work. The current soft computation models shrink the number of trials and were found computationally efficient as the MCS-based FE modelling. The paper presents a comparison of MARS, ANN-PSO, GPR, and ANFIS algorithm performance with the stochastic FE model based on TSDT.  相似文献   
35.
Monoclonal gammopathy of IgG3 kappa type is described in a young man with diffuse lymphoid infiltration of the stomach duodenum and intestines.  相似文献   
36.

Introduction

In Quebec, Canada, receipt of the 2009 AS03-adjuvanted pandemic H1N1 vaccine was associated with increased risk of anaphylaxis and other allergic-like events (ALE), especially among women of childbearing age. In response to this safety signal, a case–control study was conducted to identify potential risk factors.

Methods

A total of 435 ALE (50 anaphylaxis) occurring <24 h following pandemic vaccination were compared to 849 age-gender matched controls randomly selected from the provincial Pandemic Influenza Vaccination Registry. More than 60 potential risk factors were evaluated through phone interviews and included demographic information, medical history, medication use or acute respiratory illnesses (ARI) concurrent with vaccination and other risk factors associated with general allergy. Odds ratios (ORs) with 95% confidence intervals were estimated with unconditional logistic regression.

Results

Factors associated with increased risk of anaphylaxis included concurrent ARI (18% cases vs. 4% controls, ORadj 7.67, 95%CI: 3.04–13.37), food allergy (26% cases vs. 4% controls, ORadj 3.84, 95%CI: 1.51–9.74) and vaccination during the first four weeks of the campaign (66% cases vs. 50% controls, ORadj 2.16, 95%CI: 1.10–4.25) whereas alcohol exposure (≥1 drink/week) was associated with reduced risk (29% cases vs. 42% controls, ORadj 0.26, 95%CI: 0.13–0.57). These factors were also significantly associated with any ALE but the strength of association was weaker. Allergy to components found in the vaccine (e.g., egg, thimerosal) was infrequent and did not significantly differ between cases and controls.

Conclusion

Increased anaphylaxis and other allergic-like events observed in association with AS03-adjuvanted pandemic H1N1 vaccine remain mostly unexplained despite extensive risk factor review. However, prior to mass vaccination with similar formulations this safety signal warrants further consideration and better understanding. In particular, the predominance among women of childbearing age may be a clue to underlying biological or hormonal influences on adverse immunological responses to vaccine.  相似文献   
37.
In a previous study we showed that tumorigenic and invasive human uroepithelial cell lines are characterized by the presence of sialosyl Lea (sLea) ganglioside. Our data suggested that expression of this glycolipid correlated with acquisition of the malignant phenotype by human urothelial cells. To evaluate the postulated adhesion function of sLea antigen, we studied the adherence of 6 human urothelial cell lines with different expressions of this carbohydrate structure to E-selectin-expressing CHO cells. The only cell line that bound specifically to E-selectin was Hu 1703He, which expressed the highest level of sLea antigen. The involvement of carbohydrate-E-selectin interaction in the adhesion of Hu 1703He cells was indicated by the following facts: (i) anti-E-selectin monoclonal antibody (MAb) completely abolished binding to E-selectin-expressing CHO cells; (ii) removal of sialic acid from Hu 1703He cells highly decreased the adhesion. Adhesion correlated with the presence of several sLea-carrying glycoproteins, which was shown by immunoblotting of Hu 1703He cell lysate with anti-sLea MAb 19-9. The binding of antibody was abolished when cell lysate was treated with O-sialoglycoprotein endopeptidase, suggesting that sLea is present on O-linked oligosaccharides. However, incubation of Hu 1703He cells with O-sialoglycoprotease had no effect on adhesion to E-selectin or on binding of 19-9 MAb to the cell surface. Our data suggest that (i) protein-bound sLea oligosaccharides represent only a minor portion of whole sLea antigen produced by uroepithelial cells; (ii) effective binding to E-selectin occurs when sLea oligosaccharide present on cell-surface glycosphingolipids is expressed in high density since the cell lines with moderate expression of sLea ganglioside did not bind to E-selectin-transfected CHO cells. © 1996 Wiley-Liss, Inc.  相似文献   
38.
39.
The epidemiology of suicide in Thailand from 1977-2002 was presented. In the years 1977 and 2002, the suicide rates were 5.9 and 7.8 per 100,000 population. This is low compared to nearby Asian countries. The highest suicide rate was 8.6 per 100,000 in the year 1999, a time of economic crisis. The ratio of male to female suicide rate was 1.14:1 in the year 1977 and increased to 3.16:1 in the year 2002. The highest suicide rate was in young males, ages 25-29 and the trend shows an increase. Despite the increasing incidence, there has been little study to date; however, HIV/AIDS has been identified as a major risk factor.  相似文献   
40.
BACKGROUND: The balance of CD28/CTLA4-derived signals and Fas-dependent apoptosis activity is determined by the peripheral defense mechanisms and might play a role in the pathogenesis of allergy. OBJECTIVES: The aim of the study was to investigate the expression of costimulatory and pro- and antiapoptotic molecules in adenoid T cells of children suffering from allergic rhinitis and to find out which of these molecules have a predictive value in the development of allergic rhinitis. METHODS: The adenoids of 60 children, removed because of nasal obstruction, chronic rhinitis and recurrent respiratory infection, were evaluated. Patients were divided into two groups: group 1, suffering from chronic allergic rhinitis, and group 2, suffering from chronic rhinitis, where no specific IgE was detected, including children with a positive family history of allergy (group 2a) and children with neither a personal nor a family history of allergy (group 2b). For immunohistochemical stainings anti-CD3, anti-CD19, anti-CD4, anti-CD8, anti-CD25, anti-CD28, anti-CTLA4 (CD152), anti-bcl-2, anti-Fas, and anti-FasL antibodies were used. The number of cells expressing these molecules was identified in adenoid interfollicular spaces. The results were then analyzed in allergic and nonallergic children. During a 24-month follow-up children were re-examined for allergy and results were compared to previous immunohistochemical evaluations. RESULTS: The expression of CD4, CD25, CD28, FasL, and CTLA4 was significantly increased in group 1 compared to group 2 (p < 0.05). However, the discriminant analysis confirmed that only CTLA4 and FasL expression fully discriminated allergic subjects from the others. During a 24-month period of observation 8 children from group 2a were also diagnosed with allergic rhinitis. All of them, especially those sensitized to mites, had an increased number of FasL+ and CTLA4+ in previously removed adenoids. CONCLUSION: An increased number of cells with intracellular expression of FasL and CTLA4, in interfollicular spaces of adenoids, seems to be a predictive factor of the development of allergic rhinitis.  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