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   1294篇
  免费   125篇
  国内免费   15篇
耳鼻咽喉   9篇
儿科学   73篇
妇产科学   63篇
基础医学   170篇
口腔科学   62篇
临床医学   163篇
内科学   242篇
皮肤病学   38篇
神经病学   82篇
特种医学   146篇
外科学   118篇
综合类   69篇
预防医学   80篇
眼科学   9篇
药学   66篇
中国医学   2篇
肿瘤学   42篇
  2023年   12篇
  2022年   9篇
  2021年   25篇
  2020年   18篇
  2019年   30篇
  2018年   24篇
  2017年   23篇
  2016年   24篇
  2015年   44篇
  2014年   46篇
  2013年   50篇
  2012年   41篇
  2011年   42篇
  2010年   58篇
  2009年   51篇
  2008年   48篇
  2007年   53篇
  2006年   39篇
  2005年   40篇
  2004年   29篇
  2003年   36篇
  2002年   32篇
  2001年   29篇
  2000年   31篇
  1999年   29篇
  1998年   47篇
  1997年   45篇
  1996年   45篇
  1995年   28篇
  1994年   40篇
  1993年   33篇
  1992年   19篇
  1991年   23篇
  1990年   21篇
  1989年   27篇
  1988年   24篇
  1987年   23篇
  1986年   22篇
  1985年   13篇
  1984年   12篇
  1983年   13篇
  1982年   17篇
  1981年   16篇
  1980年   18篇
  1979年   5篇
  1978年   7篇
  1977年   14篇
  1976年   9篇
  1975年   6篇
  1973年   5篇
排序方式: 共有1434条查询结果,搜索用时 15 毫秒
51.

Background

22q11.2 deletion syndrome (22q11.2DS) is a common microdeletion syndrome, which occurs in approximately 1:4000 births. Familial autosomal dominant recurrence of the syndrome is detected in about 8-28% of the cases. Aim of this study is to evaluate the intergenerational and intrafamilial phenotypic variability in a cohort of familial cases carrying a 22q11.2 deletion.

Methods

Thirty-two 22q11.2DS subjects among 26 families were enrolled.

Results

Second generation subjects showed a significantly higher number of features than their transmitting parents (212 vs 129, P?=?0.0015). Congenital heart defect, calcium-phosphorus metabolism abnormalities, developmental and speech delay were more represented in the second generation (P?<?0.05). Ocular disorders were more frequent in the parent group. No significant difference was observed for the other clinical variables. Intrafamilial phenotypic heterogeneity was identified in the pedigrees. In 23/32 families, a higher number of features were found in individuals from the second generation and a more severe phenotype was observed in almost all of them, indicating the worsening of the phenotype over generations. Both genetic and epigenetic mechanisms may be involved in the phenotypic variability.

Conclusions

Second generation subjects showed a more complex phenotype in comparison to those from the first generation. Both ascertainment bias related to patient selection or to the low rate of reproductive fitness of adults with a more severe phenotype, and several not well defined molecular mechanism, could explain intergenerational and intrafamilial phenotypic variability in this syndrome.  相似文献   
52.
53.
Behçet’s disease is a rare disease characterised by recurrent oral ulcers, with systemic manifestations including genital ulcers, ocular disease, skin lesions, gastrointestinal disease, neurologic disease, vascular disease and arthritis. Most clinical manifestations of Behçet’s disease are believed to be due to vasculitis. The heterogeneous clinical spectrum is influenced by sex, ethnicity and country of residence. Vascular manifestation in the form of isolated large brachial artery aneurysm is rare in children. Treatment involves aneurysmorrhaphy to avoid rupture or ischaemic sequelae in addition to lifelong medical management to control vasculitis.  相似文献   
54.
55.
Introduction Retention in HIV care and adherence to antiretroviral therapy (ART) during pregnancy and postpartum for women living with HIV (WLWH) are necessary to optimize health outcomes for women and infants. The objective of this study was to evaluate the impact of two evidenced‐based behavioural interventions on postpartum adherence and retention in WLWH in Kenya.MethodsThe Mother‐Infant Visit Adherence and Treatment Engagement (MOTIVATE) study was a cluster‐randomized trial enrolling pregnant WLWH from December 2015 to August 2017. Twenty‐four health facilities in southwestern Kenya were randomized to: (1) standard care (control), (2) text‐messaging, (3) community‐based mentor mothers (cMM) or (4) text‐messaging and cMM. Primary outcomes included retention in care and ART adherence at 12 months postpartum. Analyses utilized generalized estimating equations and competing risks regression. Per‐protocol analyses examined differences in postpartum retention for women with high versus low levels of exposure to the interventions.Results We enrolled 1331 pregnant WLWH (mean age 28 years). At 12 months postpartum, 1140 (85.6%) women were retained in care, 96 women (7.2%) were lost‐to‐follow‐up (LTFU) and 95 (7.1%) were discontinued from the study. In intention‐to‐treat analyses, the relative risk of being retained at 12‐months postpartum was not significantly higher in the intervention arms versus the control arm. In time‐to‐event analysis, the cMM and text arm had significantly lower rates of LTFU (hazard ratio 0.44, p = 0.019). In per‐protocol analysis, the relative risk of 12‐month postpartum retention was 24–29% higher for women receiving at least 80% of the expected intervention compared to the control arm; text message only risk ratio (RR) 1.24 (95% confidence interval [CI] 1.16–1.32, p<0.001), cMM only RR 1.29 (95% CI 1.21–1.37, p<0.001) and cMM plus text RR 1.29 (1.21–1.37, p<0.001). Women LTFU were younger (p<0.001), less likely to be married (p<0.001) and more likely to be newly diagnosed with HIV during pregnancy (p<0.001). Self‐reported ART adherence did not vary by study arm.ConclusionsBehavioural interventions using peer support and text messages did not appear to improve 12‐month postpartum retention and adherence in intention‐to‐treat analyses. Higher levels of exposure to the interventions may be necessary to achieve the desired effects.  相似文献   
56.
57.
58.

Background

Osteoporosis is characterised by low bone mineral density (BMD) leading to an increased risk of fracture. Patients who have sustained a significant traumatic brain injury may have an increased risk of secondary reduced BMD as a result of immobility and other factors.

Objectives

To describe BMD in a cohort of patients recovering from traumatic brain injury, and to discuss the implications of the findings for physiotherapy practice.

Design

Prospective, observational.

Setting

Specialist, residential unit providing care for individuals with brain injury, many with a history of severe challenging behaviour.

Participants

Current inpatients (n = 51, 80% male) with the capacity to provide consent, as judged by their responsible clinician. The median age was 41 years (range 20 to 60 years), and the median time since the brain injury was sustained was 22 years (range 4 to 54 years).

Methods

Participants’ BMD was measured at the radius and tibia using quantitative ultrasound. Various clinical and demographic details were collected.

Results

Participants had suboptimal BMD measurements that were generally low for their age and gender. Nine (18%) participants met the criteria for osteopenia measured at the radius, and 26 (51%) participants met criteria for osteoporosis or osteopenia measured at the tibia.

Conclusions

Some participants had reduced BMD, putting them at risk of fracture or of developing such risk in the future. This group is at particular risk because they frequently display challenging aggressive behaviours that may be met with responses including proportionate use of manual restraint. Physiotherapists should bear this increased risk in mind when devising exercise programmes assessing risk in neurobehavioural rehabilitation settings.  相似文献   
59.
Our goal was to study deglutition of Parkinson??s disease (PD) patients and normal controls (NC) using surface electromyography (sEMG). The study included 15 patients with idiopathic PD and 15 age-matched normal controls. Surface electromyography was collected over the suprahyoid muscle group. Conditions were the following: swallow at once 10 and 20?ml of water and 5 and 10?ml of yogurt of firm consistency, and freely drink 100?ml of water. During swallowing, durations of sEMG were significantly longer in PD patients than in normal controls but no significant differences of amplitudes were found. Eighty percent of the PD patients and 20?% of the NC needed more than one swallow to consume 20?ml of water, while 70?% of the PD patients and none of the NC needed more than one swallow to consume 5?ml of yogurt. PD patients took significantly more time and needed significantly more swallows to drink 100?ml of water than normal controls. We conclude that sEMG might be a simple and useful tool to study and monitor deglutition in PD patients.  相似文献   
60.
Leishmania parasites cause a spectrum of clinical pathology in humans ranging from disfiguring cutaneous lesions to fatal visceral leishmaniasis. We have generated a reference genome for Leishmania mexicana and refined the reference genomes for Leishmania major, Leishmania infantum, and Leishmania braziliensis. This has allowed the identification of a remarkably low number of genes or paralog groups (2, 14, 19, and 67, respectively) unique to one species. These were found to be conserved in additional isolates of the same species. We have predicted allelic variation and find that in these isolates, L. major and L. infantum have a surprisingly low number of predicted heterozygous SNPs compared with L. braziliensis and L. mexicana. We used short read coverage to infer ploidy and gene copy numbers, identifying large copy number variations between species, with 200 tandem gene arrays in L. major and 132 in L. mexicana. Chromosome copy number also varied significantly between species, with nine supernumerary chromosomes in L. infantum, four in L. mexicana, two in L. braziliensis, and one in L. major. A significant bias against gene arrays on supernumerary chromosomes was shown to exist, indicating that duplication events occur more frequently on disomic chromosomes. Taken together, our data demonstrate that there is little variation in unique gene content across Leishmania species, but large-scale genetic heterogeneity can result through gene amplification on disomic chromosomes and variation in chromosome number. Increased gene copy number due to chromosome amplification may contribute to alterations in gene expression in response to environmental conditions in the host, providing a genetic basis for disease tropism.  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