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   2238篇
  免费   212篇
  国内免费   17篇
耳鼻咽喉   8篇
儿科学   79篇
妇产科学   62篇
基础医学   253篇
口腔科学   57篇
临床医学   277篇
内科学   423篇
皮肤病学   30篇
神经病学   135篇
特种医学   172篇
外科学   326篇
综合类   77篇
预防医学   227篇
眼科学   11篇
药学   191篇
中国医学   1篇
肿瘤学   138篇
  2023年   23篇
  2022年   19篇
  2021年   45篇
  2020年   28篇
  2019年   40篇
  2018年   53篇
  2017年   32篇
  2016年   33篇
  2015年   33篇
  2014年   46篇
  2013年   67篇
  2012年   76篇
  2011年   73篇
  2010年   70篇
  2009年   68篇
  2008年   84篇
  2007年   100篇
  2006年   103篇
  2005年   78篇
  2004年   74篇
  2003年   69篇
  2002年   79篇
  2001年   66篇
  2000年   63篇
  1999年   54篇
  1998年   47篇
  1997年   41篇
  1996年   58篇
  1995年   53篇
  1994年   32篇
  1993年   40篇
  1992年   41篇
  1991年   41篇
  1990年   63篇
  1989年   48篇
  1988年   35篇
  1987年   52篇
  1986年   24篇
  1985年   22篇
  1984年   26篇
  1983年   24篇
  1980年   16篇
  1979年   24篇
  1978年   19篇
  1977年   22篇
  1976年   19篇
  1975年   22篇
  1973年   25篇
  1970年   23篇
  1969年   18篇
排序方式: 共有2467条查询结果,搜索用时 15 毫秒
61.
ObjectiveTo evaluate responses by people with knee osteoarthritis to a brief educational video about their condition that aimed to empower and motivate effective self-management. The video content addressed psychosocial contributors to pain and barriers to behaviour change.MethodsA mixed methods design, including a survey and semi-structured interviews, was used to collect data from 118 people (46–83 years, 78% female) with knee osteoarthritis.ResultsQuantitative data analysis showed the video was rated positively on 0–6 scales for enjoyability (mean 5.0), helpfulness (4.9), relevance (5.0) and believability (5.4). The majority would recommend the video (89%), learned new information (78%) and/or reported intentions to change behaviour (78%). A minority disliked aspects of the video (23%). The thematic analyses identified three main themes: Reactions to the video, including emotions; Learning from the video, including new knowledge and empowerment, but also unmet information needs or disagreement; and Intentions, including behaviour changes, cognitive changes and help seeking.ConclusionEducation about knee osteoarthritis with a focus on empowerment is well received by people with the condition, although some discordant views emerged.Practice implicationsThe educational video about knee osteoarthritis can be recommended to promote effective self-management and counteract potential drawbacks associated with biomedical-based education.  相似文献   
62.
Milroy disease (MD) is an autosomal dominantly inherited primary lymphedema. In 1998, the gene locus for MD was mapped to 5q35.3 and variants in the VEGFR3 (FLT4) gene, encoding vascular endothelial growth factor receptor 3 (VEGFR3), were identified as being responsible for the majority of MD cases. Several reports have since been published detailing pathogenic FLT4 mutations. To date, a total of 58 different variants in FLT4, 20 of which are unpublished, have been observed in 95 families with MD. A review of published mutations is presented in this update. Furthermore, the unpublished variants are presented including clinical data. Comparison of clinical features in patients and their families with the same mutations reveals incomplete penetrance and variable expression, making genotype–phenotype correlations difficult. Most mutations are missense, but a few deletions and one splicing variant have also been reported. Several animal models have confirmed the role of VEGFR3 in lymphangiogenesis and studies show mutant VEGFR3 receptors are not phosphorylated. Here, an MD patient with the same p.Ile1053Phe change as seen in the Chy mouse is presented for the first time. This finding confirms that this mouse lineage is an excellent model for MD. All the data reviewed here has been submitted to a database based on the Leiden Open (source) Variation Database (LOVD) and is accessible online at www.lovd.nl/flt4.  相似文献   
63.
64.
65.
66.
Alzheimer's disease (AD) is a complex and slowly progressing dementing disorder that results in neuronal and synaptic loss, deposition in brain of aberrantly folded proteins, and impairment of spatial and episodic memory. Most studies of mouse models of AD have employed analyses of cognitive status and assessment of amyloid burden, gliosis, and molecular pathology during disease progression. Here we sought to understand the behavioral, cellular, ultrastructural, and molecular changes that occur at a pathological stage equivalent to the early stages of human AD. We studied the TgCRND8 mouse, a model of aggressive AD amyloidosis, at an early stage of plaque pathology (3 months of age) in comparison to their wildtype littermates and assessed changes in cognition, neuron and spine structure, and expression of synaptic glutamate receptor proteins. We found that, at this age, TgCRND8 mice display substantial plaque deposition in the neocortex and hippocampus and impairment on cued and contextual memory tasks. Of particular interest, we also observed a significant decrease in the number of neurons in the hippocampus. Furthermore, analysis of CA1 neurons revealed significant changes in apical and basal dendritic spine types, as well as altered expression of GluN1 and GluA2 receptors. This change in molecular architecture within the hippocampus may reflect a rising representation of inherently less stable thin spine populations, which can cause cognitive decline. These changes, taken together with toxic insults from amyloid‐β protein, may underlie the observed neuronal loss. J. Comp. Neurol. 522:2319–2335, 2014. © 2014 Wiley Periodicals, Inc.  相似文献   
67.

Background:

Pharmacotherapy may not sufficiently reduce neuropathic pain in many individuals post spinal cord injury (SCI). The use of alternative therapies such as surgery may be effective in reducing neuropathic pain in these individuals. However, because of the invasive nature of surgery, it is important to examine the evidence for use of this treatment.

Objective:

The purpose of this study was to conduct a systematic review of published literature on the surgical treatment of neuropathic pain after SCI.

Methods:

MEDLINE, CINAHL, EMBASE, and PsycINFO databases were searched for articles in which surgical treatment of pain after SCI was examined. Articles were restricted to the English language. Article selection was conducted by 2 independent reviewers with the following inclusion criteria: the subjects participated in a surgical intervention for neuropathic pain; at least 50% of the subjects had an SCI; at least 3 subjects had an SCI; and a definable intervention involving the dorsal root entry zone (DREZ) procedure was used to reduce pain. Data extracted included study design, study type, subject demographics, inclusion and exclusion criteria, sample size, outcome measures, and study results. Randomized controlled trials (RCTs) were assessed for quality using the Physiotherapy Evidence Database (PEDro) assessment scale. Levels of evidence were assigned to each intervention using a modified Sackett scale.

Results:

Eleven studies met the inclusion criteria. One study provided level 2 evidence, and the rest provided level 4 evidence. The DREZ procedure was shown to be more effective for segmental pain than for diffuse pain after SCI. Further, individuals with conus medullaris level injury were found to have a higher level of neuropathic pain relief than those with cervical, thoracic, or cauda equina injury.

Conclusions:

The studies demonstrated that the DREZ procedure may be effective in reducing segmental pain. Hence, DREZ may be important in treatment of neuropathic pain in individuals resistant to less invasive treatments. Because the studies lacked control conditions and examination of long-term effects, there is a need for larger trials with more stringent conditions.Key words: pain, spinal cord injury, surgical treatmentPain is a major cause of distress and disability in persons with spinal cord injury (SCI). It has been shown to lead to social isolation, unemployment, decreased function, decreased quality of life, depression, and even suicide.1,2 More than 77% of individuals with an SCI indicated that pain interfered with one or more of their daily activities including sleep (40%), exercise (34.9%), and work (33.6%).2 The International Association for the Study of Pain (IASP) defines neuropathic pain as “pain caused by a lesion or disease of the somatosensory nervous system.”3 After an SCI, individuals often report the onset of chronic neuropathic pain caudal to the level of the lesion or at the same level within the associated spinal cord segment.4 Dijkers et al5 reported no difference in the prevalence of pain based on level or completeness.The reported incidence of neuropathic pain after SCI varies greatly among studies, but between 10% and 30% of patients with SCI experience pain severe enough to interfere with their activities of daily living6,7 and may require surgical intervention to relieve persistent and refractory pain.4,8 Unmanageable neuropathic pain occurs more often in individuals with conus medullaris and cauda equina lesions where damage also involves the peripheral nerve roots.8When pharmacological and other noninvasive treatments fail to reduce pain, surgical spinal cord stimulation and dorsal root entry zone (DREZ) ablation treatments, such as DREZ lesioning and microsurgical DREZotomy (MDT), can be considered as options for the management of refractory pain.9 Neurosurgical procedures to reduce neuropathic pain should be reserved for cases in which medical therapies have failed to sufficiently reduce pain.4 The risks associated with ablative surgeries can be significant for individuals with incomplete neurological deficits; therefore, DREZ ablation is generally only considered a treatment option when neuropathic pain is present after a complete SCI.8 The MDT procedure targets for ablation the nociceptive fibers in the lateral bundle of the dorsal rootlet, the deafferented neurons of the dorsal horn, and the medial portion of the Lissauer tract.4,6 This systematic review was conducted to assess the effectiveness of DREZ ablation therapies in reducing neuropathic pain in individuals following SCI.  相似文献   
68.
69.

Purpose

Biometals such as zinc and copper have been shown to affect tight junction expression and subsequently blood-brain barrier (BBB) integrity. Whether these biometals also influence the expression and function of BBB transporters such as P-glycoprotein (P-gp) however is currently unknown.

Methods

Using the immortalised human cerebral microvascular endothelial (hCMEC/D3) cell line, an in-cell western assay (alongside western blotting) assessed relative P-gp expression after treatment with the metal ionophore clioquinol and biometals zinc and copper. The fluorescent P-gp substrate rhodamine-123 was employed to observe functional modulation, and inductively coupled plasma mass spectrometry (ICP-MS) provided information on biometal trafficking.

Results

A 24-h treatment with clioquinol, zinc and copper (0.5, 0.5 and 0.1 μM) induced a significant upregulation of P-gp (1.7-fold) assessed by in-cell western and this was confirmed with western blotting (1.8-fold increase). This same treatment resulted in a 23% decrease in rhodamine-123 accumulation over a 1 h incubation. ICP-MS demonstrated that while t8his combination treatment had no effect on intracellular zinc concentrations, the treatment significantly enhanced bioavailable copper (4.6-fold).

Conclusions

Enhanced delivery of copper to human brain microvascular endothelial cells is associated with enhanced expression and function of the important efflux pump P-gp, which may provide therapeutic opportunities for P-gp modulation.
  相似文献   
70.
OBJECTIVE: To develop a new model to improve risk prediction for admissions to adult critical care units in the UK. DESIGN: Prospective cohort study. SETTING: The setting was 163 adult, general critical care units in England, Wales, and Northern Ireland, December 1995 to August 2003. PATIENTS: Patients were 216,626 critical care admissions. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The performance of different approaches to modeling physiologic measurements was evaluated, and the best methods were selected to produce a new physiology score. This physiology score was combined with other information relating to the critical care admission-age, diagnostic category, source of admission, and cardiopulmonary resuscitation before admission-to develop a risk prediction model. Modeling interactions between diagnostic category and physiology score enabled the inclusion of groups of admissions that are frequently excluded from risk prediction models. The new model showed good discrimination (mean c index 0.870) and fit (mean Shapiro's R 0.665, mean Brier's score 0.132) in 200 repeated validation samples and performed well when compared with recalibrated versions of existing published risk prediction models in the cohort of patients eligible for all models. The hypothesis of perfect fit was rejected for all models, including the Intensive Care National Audit & Research Centre (ICNARC) model, as is to be expected in such a large cohort. CONCLUSIONS: The ICNARC model demonstrated better discrimination and overall fit than existing risk prediction models, even following recalibration of these models. We recommend it be used to replace previously published models for risk adjustment in the UK.  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