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   496篇
  免费   31篇
儿科学   5篇
妇产科学   2篇
基础医学   73篇
口腔科学   28篇
临床医学   32篇
内科学   125篇
皮肤病学   3篇
神经病学   43篇
特种医学   19篇
外科学   53篇
综合类   2篇
预防医学   19篇
药学   68篇
中国医学   2篇
肿瘤学   53篇
  2023年   4篇
  2021年   5篇
  2020年   7篇
  2019年   8篇
  2018年   7篇
  2017年   5篇
  2016年   5篇
  2015年   5篇
  2014年   16篇
  2013年   17篇
  2012年   32篇
  2011年   31篇
  2010年   16篇
  2009年   13篇
  2008年   21篇
  2007年   31篇
  2006年   16篇
  2005年   14篇
  2004年   14篇
  2003年   10篇
  2002年   12篇
  2001年   12篇
  2000年   12篇
  1999年   11篇
  1998年   9篇
  1997年   5篇
  1996年   7篇
  1994年   7篇
  1992年   10篇
  1991年   9篇
  1990年   14篇
  1989年   15篇
  1988年   6篇
  1987年   13篇
  1986年   3篇
  1985年   13篇
  1984年   10篇
  1983年   6篇
  1982年   6篇
  1981年   6篇
  1980年   9篇
  1979年   3篇
  1978年   6篇
  1977年   6篇
  1976年   6篇
  1975年   3篇
  1974年   6篇
  1973年   9篇
  1971年   4篇
  1970年   3篇
排序方式: 共有527条查询结果,搜索用时 15 毫秒
101.
    
Removable prosthodontics are often associated with mechanical troubles in daily use, such as fracture or deformation. These troubles render prostheses unusable and reduce wearers’ QOL. Various reinforcements are used to prevent such problems, but consensus on reinforcement has not been reached. This review aimed to summarise the effects of reinforcement and to propose favourable reinforcement based on material, design and position in the prostheses. Initially, 139 articles were selected by electronic and manual searches. After exclusion of 99 articles based on the exclusion criteria, 40 articles were finally included in the review. Electronic searches were performed for articles published from 2005 to 2015 in PubMed, EMBASE, MEDLINE and Cochrane Library, and manual searches were performed in 10 journals relevant to the topic of removable prosthodontics. For in vitro studies, certain dental alloys and fibres were mainly used. Their forms were different, including complicated forms in dental alloys and various forms in fibres. The materials were examined for mechanical properties like fracture strength, flexural strength and elastic modulus and compared with one another or without reinforcement. There were a few clinical studies and one longitudinal study. Cast metal reinforcement seemed to be most favourable in terms of fracture toughness and stiffness. The most favourable forms differed depending on the prostheses, but placement around thin and deformable areas was effective. However, randomised or longitudinal clinical reports and comparative clinical studies on the use of reinforcement were still lacking and such studies are necessary in the future.  相似文献   
102.
    

Background

Transesophageal Doppler echocardiography has shown that significant stenosis can be detected based on the presence of aliasing with color Doppler in the stenotic area. The study aimed to assess the detection of angiographically significant coronary stenosis (ASCS) by analyzing the characteristics and velocities of resting coronary artery flow (RCF) using transthoracic coronary Doppler echocardiography (TCDE).

Methods

TCDE was performed before diagnostic coronary angiography (CA). The following velocities were measured: peak systolic velocity (PSV), peak diastolic velocity (PDV), mean diastolic velocity (MDV), end-diastolic velocity (EDV), and distal to proximal velocity ratios.

Results

Twenty-five patients were included, and CA revealed ASCS in 14 patients. With TCDE, the proximal and distal portions of the left anterior descending artery (LAD) could be measured in 84% of cases. Among 12 patients with ASCS in the distal left main coronary artery (LMCA) or proximal or mid LAD, proximal and distal flow could be measured in ten patients. Proximal diastolic velocities were higher in patients with ASCS in the LAD, and a distal MDV/proximal MDV ratio < 0.5 had a 60% sensitivity and a 92% specificity for the detection of ASCS (AUC 0.77, 95% CI 0.56–0.92). For the detection of ASCS limited to the LMCA and/or proximal LAD, the distal MDV/proximal MDV ratio had a sensitivity of 100% and a specificity of 89% (AUC 0.98, 95% CI 0.81–0.99).

Conclusions

Resting TCDE can detect ASCS in the LAD, particularly at the proximal level, analyzing the ratio between distal and proximal flow velocities. These results could not be demonstrated in the RCA and CX arteries.
  相似文献   
103.
Preoperative evaluation of a patient with adrenal carcinoma and hepatic metastases was performed by arteriography, computed tomography (CT) and computed tomographic arteriography (CTA). Early and complete demonstration of tumor involvement by these imaging modalities allowed an accurate assessment of tumor extension and subsequent aggressive surgical removal of the primary as well as the metastasis in the liver.  相似文献   
104.
An acidic polysaccharide, designated as MVS-IVA, was isolated from the seeds of Malva verticillata. It showed a remarkable reticuloendothelial system potentiating activity in the carbon clearance test. Chemical and spectroscopic studies demonstrated that the polysaccharide is rich in alpha-L-arabinofuranose residues and possesses mainly an alpha-1,5-linked L-arabino-beta-3,6-branched-D-galactan structure accompanied with rhamnogalacturonan type units. Both alpha-1,3-linked L-arabinopyranose and beta-1,4-linked D-xylopyranose residues were also identified as component units. MVS-IVA contains a small amount of protein (3.3%).  相似文献   
105.
106.
107.
BackgroundAlthough it has been described that affective temperaments are associated with the 5-HTTLPR, less attention was paid to the association between this polymorphism and subscales and items related to each affective temperament. The aim of our study was to investigate the association of affective temperament subscales and individual items with the s allele of the 5-HTTLPR.Method138 psychiatrically healthy women completed the TEMPS-A questionnaire and were genotyped for 5-HTTLPR. Scores of subjects on the temperament scales, subscales and items in the three genotype and the two phenotype groups were compared using ANOVA. We selected items with significantly different mean scores between the three genotype groups and the two phenotype groups separately and performed item analysis.ResultsSubjects in the different 5-HTTLPR genotype and phenotype groups have significantly different score on scales measuring depressive, cyclothymic, irritable and anxious temperaments, and several subscales composing these temperamental scales. Subjects in the three genotype groups scored significantly different on 11 items, 8 of these remained in a derived genotype scale after item analysis. Subjects in the two phenotype groups had significantly different scores on 12 items, 9 of them were retained in a derived phenotype scale after item analysis.LimitationsOur sample was relatively small and included only women.ConclusionsOur data provide support for the association of affective temperaments with the s allele. Although the cyclothymic temperament shows the strongest association, all temperaments within the depressive superfactor have a similar share in this association. The newly derived 5-HTTLPR Phenotype Scale shows strong association with 5-HTTLPR genotype and phenotype, therefore this scale should be further investigated in relation to psychiatric disorders, as well as psychological traits and temperaments.  相似文献   
108.

Background

Adolescent self-harm (SH) is a major health problem potentially associated with poor outcomes including reduced life expectancy and risk of completed suicide in adulthood. Several studies point to the role of possible constitutional vulnerabilities that could predispose to this behavior. This study sets out to assess the relationship between SH and affective temperaments (AT) in adolescents.

Methods

A cross-sectional sample of public school students (n=1713), with age limits between 12 and 20, was examined using anonymously completed self-report instruments including ‘The Lifestyle & Coping Questionnaire’ and the ‘Temperament Evaluation of Memphis, Pisa, Paris and San Diego—auto-questionnaire’ (TEMPS-A). SH was defined according to strict criteria through a two-stage procedure. Statistical significance of associations with SH for categorical variables was assessed in bivariate analysis. AT predictors of lifetime SH were examined in multivariate logistic regression analyses.

Results

Lifetime SH was reported by 7.3%, being about three times more frequent in females. SH was associated, in both genders, with a significant deviation on depressive, cyclothymic and irritable dimensions of TEMPS-A. After multivariate logistic regression adjusted to family typology, smoking status, alcohol and drug consumption, only depressive temperament remained significantly associated as a predictor of SH in both genders.

Limitations

The use of self-rating instruments and the cross-sectional nature of the study limit our results.

Conclusions

Cyclothymic, irritable and especially depressive temperament might represent an important marker of vulnerability to SH in both male and female adolescents.  相似文献   
109.
110.
Stromal cells in lymphoid tissues provide microenvironmental fields required for the triggering of efficient immune responses. Fibroblastic reticular cells (FRCs) are one of the integral constituents of such stromal fields; they construct the reticular network and are considered to regulate immune cells' behavior. However, the factors that mediate the interaction between lymphocytes and FRCs are poorly understood. Here we show that a mouse lymph node (LN)-derived FRC cell line, BLS4, expresses a transmembrane chemokine, CXC chemokine ligand (CXCL) 16, in response to tumor necrosis factor alpha (TNFalpha) and IFNgamma. TNFalpha-induced expression of CXCL16 depends on NFkappaB, p38 MAPK and PKA. Matrix metalloproteinase activity is required for producing soluble CXCL16 in the culture supernatant, likely via shedding at the juxtamembrane region of the extracellular domain. IL-12 enhances the expression of CXCR6 in anti-CD3/CD28-stimulated CD8+ T cells and their adhesion to the BLS4 cell surface in a TNFalpha-dependent fashion. The adherence is significantly inhibited in the presence of both anti-CXCL16 and anti-vascular cell adhesion molecule 1 (VCAM-1) antibodies. CXCL16 expression is also detected in the FRCs in LN sections and in gp38+VCAM-1+ FRCs isolated from LNs. Taken together, these findings suggest that CXCL16 is an important mediator of lymphocyte-stromal interaction within lymphoid tissues.  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