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   307篇
  免费   23篇
  国内免费   2篇
耳鼻咽喉   2篇
儿科学   6篇
妇产科学   3篇
基础医学   32篇
口腔科学   7篇
临床医学   12篇
内科学   83篇
皮肤病学   6篇
神经病学   47篇
特种医学   8篇
外科学   42篇
一般理论   1篇
预防医学   9篇
眼科学   1篇
药学   27篇
肿瘤学   46篇
  2024年   1篇
  2023年   4篇
  2022年   2篇
  2021年   6篇
  2020年   5篇
  2019年   11篇
  2018年   10篇
  2017年   5篇
  2016年   5篇
  2015年   6篇
  2014年   10篇
  2013年   12篇
  2012年   14篇
  2011年   16篇
  2010年   9篇
  2009年   4篇
  2008年   19篇
  2007年   16篇
  2006年   13篇
  2005年   14篇
  2004年   10篇
  2003年   11篇
  2002年   14篇
  2001年   4篇
  2000年   11篇
  1999年   6篇
  1998年   9篇
  1997年   4篇
  1996年   10篇
  1995年   4篇
  1994年   2篇
  1993年   3篇
  1992年   5篇
  1991年   6篇
  1990年   2篇
  1989年   5篇
  1988年   7篇
  1987年   1篇
  1986年   6篇
  1985年   3篇
  1984年   3篇
  1980年   2篇
  1979年   2篇
  1974年   1篇
  1973年   3篇
  1970年   1篇
  1969年   4篇
  1968年   3篇
  1967年   6篇
  1966年   2篇
排序方式: 共有332条查询结果,搜索用时 15 毫秒
1.
The amphibian micronucleus test has been widely used during the last 30 years to test the genotoxic properties of several chemicals and as a tool for ecogenotoxic monitoring. The vast majority of these studies were performed on peripheral blood of urodelan larvae and anuran tadpoles and to a lesser extent adults were also used. In this study, we developed protocols for measuring micronuclei in adult shed skin cells and larval gill cells of the Italian crested newt (Triturus carnifex). Amphibians were collected from ponds in two protected areas in Italy that differed in their radon content. Twenty‐three adult newts and 31 larvae were captured from the radon‐rich pond, while 20 adults and 27 larvae were taken from the radon‐free site. The animals were brought to the laboratory and the micronucleus test was performed on peripheral blood and shed skins taken from the adults and on larval gills. Samples from the radon‐rich site showed micronucleus frequencies higher than those from the radon‐free site and the difference was statistically significant in gill cells (P < 0.00001). Moreover, the larval gills seem to be more sensitive than the adult tissues. This method represents an easy (and noninvasive in the case of the shed skin) application of the micronucleus assay that can be useful for environmental studies in situ. Environ. Mol. Mutagen. 56:412–417, 2015. © 2014 Wiley Periodicals, Inc.  相似文献   
2.
The malignant phenotype of prostatic tumor cells correlates with the expression of both uPA and itscell-membrane receptor (uPAR); however, there is little information concerning the role of cell-bound uPAin matrix degradation and invasion. Our results suggest that cell-associated uPA plays a key role in regulat-ingthe amount of plasmin present at the surface of prostatic carcinoma (PRCA) cells and show that differ-entialproduction of uPA corresponds with the capacity to bind and activate plasminogen. In addition, weprovide direct evidence that both uPA secretion and the presence of uPA-uPAR complexes characterize theinvasive phenotype of PRCA cells and suggest the existence of several pathways by which tumor cells acquireplasmin activity. LNCaP cells (which do not produce uPA but express uPAR) may activate plasmin throughexogenous uPA. In vivo, the source of uPA may be infiltrating macrophages and/or fibroblasts as observedin several other systems. PAI-1 accumulation in the conditioned medium (CM) limits plasmin action to thepericellular microenvironment. Our results indicate that MMP-9 and MMP-2 are also activated by plasmingenerated by cell-bound but not by soluble, extracellular uPA. Plasmin activation and triggering of the pro-teolyticcascade involved in Matrigel invasion is blocked by antibodies against uPA (especially by anti- A-chainof uPA which interacts with uPAR) and by PA inhibitors such as p-aminobenzamidine which mayregulate levels of cell-bound uPA. uPA may also regulate growth in PRCA cells. Indeed, antibodies againstuPA A-chain (and also p-aminobenzamidine treatment) interfere with the ATF domain and inhibit cell growthin uPA-producing PC3 and DU145 prostate cancer cell lines, whereas exogenous uPA (HMW-uPA with ATF)induces growth of LNCaP prostate tumor cell line. These data support the hypothesis that in prostatic can-cerpatients at risk of progression, uPA/plasmin blockade may be of therapeutic value by blocking both growthof the primary tumor and dissemination of metastatic cells. ©Kluwer Academic Publishers  相似文献   
3.
Ageing is associated with complex remodelling in the phenotypic and functional profiles of T lymphocytes. We investigated whether expression of CD28 antigen on T cells is conserved throughout adulthood and ageing in humans. For this purpose we analysed T cells obtained from peripheral blood of 102 healthy people of ages ranging from 20 to 105 years. We found an age-related increase of CD28- T cells in percentage and absolute number, predominantly among CD8+ T cells. CD28- T cells from aged donors analysed by flow cytometry appeared as resting cells (not expressing CD25, CD38, CD69, CD71, DR), bearing markers of cytotoxic activity (CD 11b and CD 57) and with a phenotype compatible with 'memory' cells (up-regulated CD2 and CD11a; CD62L absent). At the functional level, freshly isolated purified CD28- CD8+ T cells showed high anti-CD3 redirected cytotoxic activity against Fc-bearing P815 cells. The same activity tested on freshly isolated bulk T lymphocytes was significantly augmented with age. We found a positive correlation between age, number of CD8+ CD28- T cells and anti-CD3 redirected cytotoxicity by freshly isolated T cells. These data suggest that an activation of unknown nature within the cytotoxic arm of the immune system occurs with age. We speculate that these cytotoxic T lymphocytes (CTL) in vivo may constitute armed effector cells for immediate killing of targets bearing peptides from pathogens of intracellular origin.  相似文献   
4.
HIV-associated nephropathy is a unique form of renal disease specific to HIV infection. Proteinuria and rapidly worsening azotemia in the absence of edema and hypertension are characteristic. Renal biopsy reveals collapsing and/or sclerotic glomeruli, microcystic tubular dilatation, and cellular interstitial infiltrates. Direct cytopathic effects of HIV in the setting of a particular cytokine milieu appears to be the mechanism responsible for the renal injury. There is limited therapeutic experience, but trials with steroids and angiotensin-converting enzyme inhibitors are encouraging. Dialysis is the main form of renal replacement therapy. Better understanding of the disease should improve treatment and prognosis.  相似文献   
5.
Outcomes measurement and data-triggered improvements in treatment delivery are formidable challenges, in part because of their inherent interdependence. Outcomes systems need to provide reliable, valid and comparable data that can also guide transitions in care delivery. While there is much empirical support for the efficacy of psychiatric and behavioral healthcare interventions, it is incumbent upon those who know both the literature and clinical practice to participate in setting the future course of behavioral healthcare by stirring together the seemingly immiscible aims of good business and good care. This paper briefly reviews the importance of outcomes measurement systems and their use in redesigning treatment delivery in behavioral healthcare. It then describes a clinical care model now being implemented at Park Nicollet Medical Center, incorporating clinical and operational considerations, clinical outcomes measures and algorithms or decision trees into a framework for redesigning treatment and improving the delivery of appropriate clinical care.  相似文献   
6.
The present study was aimed at identifying somatostatin receptor subtypes on the basis of their ligand-binding properties in the rat somatosensory cortex during fetal and postnatal development. Characterization of somatostatin-binding sites was performed in individual cortical layers by using three radioligands and eight competitors with known selectivities for the five somatostatin receptor subtypes. Binding sites sensitive to sst2-selective ligands were detected with high densities in the intermediate zone of the fetal cortex. From embryonic day 21 to 21 days postnatal (P21), mixed populations of receptors were detected in the cortical plate and emerging layers I-VI. Putative sst2 receptors were detected throughout the entire period but displayed different affinities for somatostatin and analogs, and a different sensitivity to GTP, depending on the developmental stage and the cortical layer considered. High densities of binding sites exhibiting characteristics of the sst1, sst3/5, and sst4 receptor subtypes were observed from P4 to P7, P7 to P14, and P7 to P21, respectively. In addition, each type of site exhibited a particular distribution pattern across the cortical layers that varied during the development. In the adult cortex, binding sites with sst1 and sst2 receptor characteristics were predominant. This study provides evidences of developmental expression windows of four sst receptor subtypes in selected areas of the rat cerebral cortex.  相似文献   
7.
8.
9.
The aim of the study was to investigate the prevalence and persistence of syncytium-inducing (SI) strains in HIV-1-infected children along time of infection and to evaluate the influence of antiretroviral therapy and host factors on viral tropism. This is a retrospective analysis carried out in 267 HIV-1 vertically infected children from an Argentinean cohort. The viral phenotype was screened in MT-2 cells and coreceptor usage confirmed by the GHOST cell assay. Also, CD4(+) T cell count, viral load, antiretroviral therapy, and human CCR5-Δ32 and CCR2-64I genotypes were analyzed. A high frequency of HIV-1 SI/CXCR4-using variants (22%) was found among children within the first trimester of life, reaching 46% after 10 years of infection. At acute infection, zidovudine prophylaxis did not significantly affect the proportions of SI HIV-1 strains, while their presence was favored by the CCR5(+)/Δ32 genotype. Interestingly, the majority of the early SI strains did not persist over time, probably due to a higher susceptibility to antiretroviral (ARV) treatment or immunologic pressure. At the chronic stage, SI variants emerged even in the presence of HAART reaching 36% at 120 months of infection. Also the HIV-1 SI phenotype was associated with lower CD4(+) T cell counts all along the course of infection. These findings highlight the need to evaluate the presence of SI/CXCR4 variants early at primary infection. This will make it possible to optimize the use of CCR5 inhibitors in children who are apparently carriers of the R5 virus preventing early therapeutic failure due to the reemergence of SI strains from reservoirs.  相似文献   
10.

Trial design

This was a multicenter cluster-randomized controlled trial.

Participants

A total of 227 patients ≥ 18 years old with a new onset of depressive symptoms who screened positive on the first two items of the Patient Health Questionnaire-9 (PHQ-9) were recruited by primary care physicians (PCPs) of eight health districts of three Italian regions from September 2009 to June 2011.

Intervention

PCPs of the intervention group received a specific collaborative care program including 2 days of intensive training, implementation of a stepped care protocol, depression management toolkit and scheduled meetings with a dedicated consultant psychiatrist.

Objective

The objective was to determine whether a collaborative care program for depression management in primary care leads to higher remission rate than usual PCP care.

Outcomes

Outcome was clinical remission as expressed on PHQ-9 < 5 at 3 months.

Randomization

An independent researcher used computer-generated randomization to assign involved primary care groups to the two alternative arms.

Blinding

PCPs and research personnel were not blinded.

Results

The 223 PCPs enrolled recruited 227 patients (128 in collaborative care arm, 99 in the usual care arm). At 3 months (n= 210), the proportion of patients who achieved remission was higher, though the difference was not statistically significant, in the collaborative care group. The effect size was of 0.11. When considering only patients with minor/major depression, collaborative care appeared to be more effective than usual care (P= .015).

Conclusions

The present intervention for managing depression in primary care, designed to be applicable to the Italian context, appears to be effective and feasible.  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