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   1396篇
  免费   117篇
  国内免费   8篇
耳鼻咽喉   9篇
儿科学   50篇
妇产科学   38篇
基础医学   257篇
口腔科学   19篇
临床医学   160篇
内科学   404篇
皮肤病学   16篇
神经病学   106篇
特种医学   26篇
外科学   107篇
综合类   2篇
一般理论   1篇
预防医学   74篇
眼科学   9篇
药学   96篇
中国医学   3篇
肿瘤学   144篇
  2024年   1篇
  2023年   12篇
  2022年   24篇
  2021年   35篇
  2020年   25篇
  2019年   26篇
  2018年   31篇
  2017年   34篇
  2016年   38篇
  2015年   48篇
  2014年   66篇
  2013年   78篇
  2012年   120篇
  2011年   125篇
  2010年   63篇
  2009年   65篇
  2008年   104篇
  2007年   81篇
  2006年   87篇
  2005年   96篇
  2004年   82篇
  2003年   93篇
  2002年   85篇
  2001年   13篇
  2000年   6篇
  1999年   9篇
  1998年   8篇
  1997年   12篇
  1996年   8篇
  1995年   7篇
  1994年   7篇
  1993年   4篇
  1992年   3篇
  1991年   5篇
  1990年   2篇
  1989年   1篇
  1988年   3篇
  1987年   2篇
  1986年   1篇
  1985年   3篇
  1984年   2篇
  1983年   2篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
  1974年   1篇
排序方式: 共有1521条查询结果,搜索用时 31 毫秒
31.
Summary In a previous study, we observed an impairment of the theophylline-induced suppressive system in recent onset IDDM patients, and demonstrated also a correlation with metabolic derangement. The aim of this study was to better investigate the relationship between theophylline sensitivity (ThS) and blood glucose/plasma insulin levels in recent onset IDDM patients subjected to preprogrammed variations by an insulin/glucose clamp with artificial pancreas. Eight patients were studied within 8 weeks from the onset of IDDM. ThS was evaluated as the ability of theophylline to inhibit blastogenic response of peripheral blood lymphocytes (PBL) to Concanavalin A (ConA), after 120 min preincubation of the cells. All patients were connected to an artificial pancreas. Through i.v. continuous insulin infusion (0.02 U/kg/h) and/or i.v. continuous glucose and saline infusion, the following experimental conditions, lasting at least 1h, were obtained: T1: relative euglycemia and normal insulinemia; T2: relative euglycemia and hyperinsulinemia; T3: hyperglycemia and normal insulinemia; T4: hyperglycemia and hyperinsulinemia. ThS was maintained in 6/8 patients at T1 and in 8/8 patients at T4. ThS was lost in 4/8 patients at T2 and T3. These data suggest that the loss of ThS induced by hyperglycemia can be corrected by hyperinsulinemia, and that it is maintained when euglycemia is accompained by hypoinsulinemia. It is lost when these two parameters lose their interrelationship.  相似文献   
32.
33.
Assessing cytomegalovirus (CMV)-specific cell-mediated immunity (CMI) represents an appealing strategy for identifying transplant recipients at risk of infection. In this study, we compared two gamma interferon-releasing assays (IGRAs), Quantiferon-CMV and CMV enzyme-linked immunosorbent spot (ELISPOT), to determine the ability of each test to predict protective CMV-specific T-cell responses. Two hundred twenty-one Quantiferon-CMV and ELISPOT tests were conducted on 120 adult kidney transplant recipients (KTRs), including 100 CMV-seropositive transplant recipients (R+) and 20 CMV-seronegative transplant recipients of a CMV-positive donor (D+/R). As a control cohort, 39 healthy adult subjects (including 33 CMV-seropositive and 6 CMV-seronegative subjects) were enrolled. CMV IgG serology was used as a reference for both tests. In the CMV-seropositive individuals, the ELISPOT and Quantiferon-CMV assays provided 46% concordance with the serology, 12% discordance, 18% disagreement between ELISPOT or Quantiferon-CMV and the serology, and 24% gray areas when one or both tests resulted in weak positives. None of the CMV-seronegative subjects showed detectable responses in the ELISPOT or the Quantiferon-CMV test. In transplant recipients, both the ELISPOT and Quantiferon-CMV assays positively correlated with each other and negatively correlated with CMV DNAemia in a significant way (P < 0.05). During the antiviral prophylaxis, all 20 D+/R KTRs we examined displayed undetectable Quantiferon-CMV and ELISPOT results, and there was no evidence of CMV seroconversion. The receiving operator curve (ROC) statistical analysis revealed similar specificities and sensitivities in predicting detectable viremia (areas under the curve [AUC], 0.66 and 0.62 for Quantiferon-CMV and ELISPOT, respectively). ELISPOT and Quantiferon-CMV values of >150 spots/200,000 peripheral blood mononuclear cells (PBMCs) and >1 to 6 IU gamma interferon (IFN-γ) were associated with protection from CMV infection (odds ratios [OR], 5 and 8.75, respectively). In transplant recipients, the two tests displayed similar abilities for predicting CMV infection. Both the ELISPOT and Quantiferon-CMV assays require several ameliorations to avoid false-negative results.  相似文献   
34.
International Journal of Mental Health and Addiction - Although the existence of dysfunctional love relationships is well known and the term “love addiction” dates back to the 1970s,...  相似文献   
35.
36.
Proteasome inhibition induces the accumulation of aggregated misfolded/ubiquitinated proteins in the aggresome; conversely, histone deacetylase 6 (HDAC6) inhibition blocks aggresome formation. Although this rationale has been the basis of proteasome inhibitor (PI) and HDAC6 inhibitor combination studies, the role of disruption of aggresome formation by HDAC6 inhibition has not yet been studied in multiple myeloma (MM). The present study aimed to evaluate the impact of carfilzomib (CFZ) in combination with a selective HDAC6 inhibitor (ricolinostat) in MM cells with respect to the aggresome‐proteolysis pathway. We observed that combination treatment of CFZ with ricolinostat triggered synergistic anti‐MM effects, even in bortezomib‐resistant cells. Immunofluorescent staining showed that CFZ increased the accumulation of ubiquitinated proteins and protein aggregates in the cytoplasm, as well as the engulfment of aggregated ubiquitinated proteins by autophagosomes, which was blocked by ricolinostat. Electron microscopy imaging showed increased autophagy triggered by CFZ, which was inhibited by the addition of ACY‐1215. Finally, an in vivo mouse xenograft study confirmed a decrease in tumour volume, associated with apoptosis, following treatment with CFZ in combination with ricolinostat. Our results suggest that ricolinostat inhibits aggresome formation, caused by CFZ‐induced inhibition of the proteasome pathway, resulting in enhanced apoptosis in MM cells.  相似文献   
37.

Background

Maternal alcohol exposure and adult alcohol intake have been shown to perturb the metabolism of various micro- and macro-nutrients, including vitamin A and its derivatives (retinoids). Therefore, it has been hypothesized that the well-known detrimental consequences of alcohol consumption may be due to deregulations of the metabolism of such nutrients rather than to a direct effect of alcohol. Alcohol exposure in utero also has long-term harmful consequences on the health of the offspring with mechanisms that have not been fully clarified. Disruption of tissue retinoid homeostasis has been linked not only to abnormal embryonic development, but also to various adult pathological conditions, including cancer, metabolic disorders and abnormal lung function. We hypothesized that prenatal alcohol exposure may permanently perturb tissue retinoid metabolism, predisposing the offspring to adult chronic diseases.

Methods

Serum and tissues (liver, lung and prostate from males; liver and lung from females) were collected from 60-75 day-old sprague dawley rats born from dams that were: (I) fed a liquid diet containing 6.7% alcohol between gestational day 7 and 21; or (II) pair-fed with isocaloric liquid diet during the same gestational window; or (III) fed ad libitum with regular rat chow diet throughout pregnancy. Serum and tissue retinoid levels were analyzed by reverse-phase high-performance liquid chromatography (HPLC). Serum retinol-binding protein (RBP) levels were measured by western blot analysis, and liver, lung and prostate mRNA levels of lecithin-retinol acyltransferase (LRAT) were measured by qPCR.

Results

Retinyl ester levels were significantly reduced in the lung of both males and females, as well as in the liver and ventral prostate of males born from alcohol-fed dams. Tissue LRAT mRNA levels remained unchanged upon maternal alcohol treatment.

Conclusions

Prenatal alcohol exposure in rats affects retinoid metabolism in adult life, in a tissue- and sex-dependent manner. We propose that the alcohol-induced perturbations of vitamin A metabolism may predispose to detrimental consequnces on adult health.  相似文献   
38.
OBJECTIVE: To assess gender differences in the long-term clinical, virological and immunological outcomes during highly active antiretroviral therapy (HAART). METHODS: This longitudinal observational multicentre study followed 2460 HIV-infected patients who had begun a protease inhibitor-based regimen for a median period of 43 months. Outcome measures were virological suppression (< 500 copies/ml), confirmed virological rebound after suppression, and death or new AIDS-defining illness (ADI). RESULTS: At baseline, 690 female patients (28.0%) had significantly lower age, higher prevalence of heterosexual contact and lower prevalence of intravenous drug use as risk factors for HIV infection compared with males. Furthermore, females had a lower number of AIDS-defining illnesses, higher CD4 cell counts and lower viral loads.No gender differences were reported in terms of proportion of patients achieving viral suppression or exhibiting rebound after achieving viral suppression. Female patients experienced reduced clinical progression during follow-up compared with males (P = 0.008) by Kaplan-Meier analysis; however this difference was not significant in an adjusted analysis. In a multivariate model, the interaction between gender and risk factor for HIV or viral load showed that female drug users and female patients with a baseline HIV RNA viral load of 10(4)-10(5) copies/ml had a favourable clinical outcome compared with males (P = 0.035 and P = 0.015, respectively). CONCLUSION: No differences were found between genders in terms of virological and immunological outcomes during long-term HAART. Nevertheless, a lower risk of clinical progression was reported among female patients with intermediate baseline viral load than in males.  相似文献   
39.

Background

Work engagement is a positive, fulfilling affective and motivational state of work-related wellbeing and a protective factor for workers' mental health. The aim of the present study was to examine the association between psychological distress (conceptualised as the target variable), job satisfaction, and work engagement in contexts of low-intensity warfare and political violence. According to the salutogenic perspective, the relationship between job satisfaction and psychological distress is influenced by the level of work engagement.

Methods

We selected a convenience sample of 380 Palestinian teachers from Gaza (40%, 152 out of 380) and the West Bank (60%, 228 out of 380). The participants were recruited on-site during morning breaks from the classroom teaching activity. The selection criteria were being in a teaching position, and working in a primary or lower secondary school. The participants completed the Arabic versions of the Teacher Job satisfaction Scale (TJSS-9), the General Health Questionnaire (GHQ-12) and the Utrecht Work Engagement Scale (UWE-SF). The statistical strategy was based on structural equation modelling. The study was approved by the Ethical Board of the University of Milano Bicocca. Informed written consent was obtained from all participants.

Findings

The General Health Questionnaire cumulative score revealed a medium to high level of psychological distress (mean 18·68 [SD 4·03]) among teachers, but high job satisfaction (mean 27·18 [SD 5·65]). The structural model showed an excellent fit (χ2 (23)=69·6, p<0·0001, NC=3·021, NFI=0·939, NNFI=0·959, CFI=0·958, RMSEA=0·073). Job satisfaction and psychological distress had a moderate and inverse relationship that was, statistically speaking, fully mediated by the level of work engagement (F=17·05, p<0·001, R2=0·16). The direct effect of job satisfaction on work engagement was positive and medium (according to Cohen, 1988) in strength.

Interpretation

The main finding of the study is that work engagement may mediate the impact of job satisfaction on teachers' psychological distress by lessening the effect of difficult working conditions. It further suggests that in order to mediate the effect of low job satisfaction on psychological distress of teachers, organisational policies and practices should focus on improving employees' work engagement. This means that, in developing job programmes for teachers in contexts characterised by difficult working conditions, the main focus must be to increase the level of subjective resources (eg, inner states, emotional activation, personal motivational processes) and workers' engagement rather than focusing primarily on job satisfaction.

Funding

None.  相似文献   
40.
Image file format is often a confusing aspect for someone wishing to process medical images. This article presents a demystifying overview of the major file formats currently used in medical imaging: Analyze, Neuroimaging Informatics Technology Initiative (Nifti), Minc, and Digital Imaging and Communications in Medicine (Dicom). Concepts common to all file formats, such as pixel depth, photometric interpretation, metadata, and pixel data, are first presented. Then, the characteristics and strengths of the various formats are discussed. The review concludes with some predictive considerations about the future trends in medical image file formats.  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