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   1589篇
  免费   82篇
  国内免费   5篇
耳鼻咽喉   10篇
儿科学   158篇
妇产科学   40篇
基础医学   266篇
口腔科学   42篇
临床医学   121篇
内科学   309篇
皮肤病学   30篇
神经病学   193篇
特种医学   17篇
外科学   94篇
综合类   21篇
一般理论   1篇
预防医学   82篇
眼科学   62篇
药学   118篇
中国医学   12篇
肿瘤学   100篇
  2024年   2篇
  2023年   13篇
  2022年   11篇
  2021年   46篇
  2020年   23篇
  2019年   40篇
  2018年   28篇
  2017年   34篇
  2016年   44篇
  2015年   43篇
  2014年   67篇
  2013年   78篇
  2012年   128篇
  2011年   129篇
  2010年   83篇
  2009年   79篇
  2008年   97篇
  2007年   105篇
  2006年   94篇
  2005年   108篇
  2004年   86篇
  2003年   81篇
  2002年   80篇
  2001年   24篇
  2000年   23篇
  1999年   14篇
  1998年   12篇
  1997年   12篇
  1996年   5篇
  1995年   7篇
  1994年   6篇
  1993年   6篇
  1992年   5篇
  1991年   6篇
  1990年   8篇
  1989年   8篇
  1988年   2篇
  1987年   2篇
  1986年   4篇
  1985年   8篇
  1983年   3篇
  1981年   3篇
  1980年   5篇
  1979年   3篇
  1978年   2篇
  1976年   2篇
  1975年   1篇
  1974年   1篇
  1971年   1篇
  1968年   1篇
排序方式: 共有1676条查询结果,搜索用时 515 毫秒
141.

Objective  

To elucidate the presence and potential involvement of brain inflammation and cell death in neurological morbidity and intractable seizures in childhood epilepsy, we quantified cell death, astrocyte proliferation, microglial activation and cytokine release in brain tissue from patients who underwent epilepsy surgery.  相似文献   
142.
143.
The present study was planned to investigate the ability of the Tinospora cordifolia to scavenge free radicals generated during aflatoxicosis. A total no. of 48 male Swiss albino mice (30 ± 5 g) were exposed to Aflatoxin B(1)(AFB(1)) (2 μg/30 g b.wt, orally) either individually or in combination with T. cordifolia (50, 100, 200 mg/kg, orally) once daily for 25 days. AFB(1) exposure led to significant rise in thiobarbituric acid reactive substances (TBARS) and fall in superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), glutathione-S-transferase (GST), glutathione peroxidase (GPx), glutathione reductase (GR), ascorbic acid, and protein content. T. cordifolia was found to show protective effect by lowering down the content of TBARS and enhancing the GSH, ascorbic acid, protein, and the activities of antioxidant enzymes viz., SOD, CAT, glutathione peroxidase, GST, and GR in kidney. Histopathological analysis of kidney samples also confirmed the protective values and antioxidant activity of ethanolic extract of herb. T. cordifolia showed protection against aflatoxin-induced nephrotoxicity due to the presence of alkaloids such as a choline, tinosporin, isocolumbin, palmatine, tetrahydropalmatine, and magnoflorine.  相似文献   
144.
Neuroblastoma is the most common extracranial solid tumor of childhood. It accounts for 15% of pediatric cancer deaths. Children with high-risk disease have a 3-year event-free survival rate of only 20%. Chemotherapy is the mainstay of treatment in children with advanced neuroblastoma. The aim of this article was to review and critically evaluate the pharmacotherapy of neuroblastoma, using peer reviewed and review literature from 2000-11. All peer reviewed, published human subject studies of therapy for neuroblastoma in children were included. Animal model and in vitro studies were included only if they added to the understanding of the mechanism of a proposed or existing human neuroblastoma therapy. Current therapeutic options for neuroblastoma involve insufficient differentiation of normal from neoplastic tissue. Critically needed new approaches will increasingly exploit targeting of therapy for unique characteristics of the neuroblastoma cell. Pharmacotherapy for neuroblastoma still suffers from an inadequate therapeutic window. Enhancement of toxicity for tumor and safety for normal tissues will entail innovation in targeting neuroblastoma cells and rescuing or protecting normal tissue elements.  相似文献   
145.
The goal was to determine recurrent or second primary status for late stomal malignancies, 16 and 17 years post-total laryngectomy in two laryngeal squamous cell carcinoma (LSCC) patients, based on DNA methylation signatures and HPV typing. Adopting a literature review based definition of late stomal recurrences as new primaries at the site of the stoma or neopharynx occurring >5 years after total laryngectomy, we employed a multi-gene candidate approach to examine promoter methylation in 24 tumor suppressor genes and PCR-based assays for HPV status offered additional insights into whether the late stomal tumors post-total laryngectomy were related or not. The primary tumor for Patient 1 was negative for HPV but had aberrant hypermethylation of APC, MLH1 and BRCA1. The stomal biopsy 17-years later showed presence of HPV-16 without any methylated genes. In Patient 2, HPV-11 and promoter methylation of APC identified in the primary tumor was also observed in the stomal malignancy 16 years post-total laryngectomy. Additional information provided by molecular typing for HPV and methylation markers underscored Patient 1's and 2's late stomal presentation as most likely a second primary and recurrence, respectively. DNA methylation markers are particularly advantageous because DNA methylation is an early event in tumorigenesis, and the epigenetic modification, 5-methylcytosine, is a stable marker. Molecular marks to discern genetic heterogeneity or relatedness of stomal malignancies several years post-total laryngectomy can provide clues to their status as either second primaries or likely recurrences. Our results support the hypothesis that a subset of stomal recurrences after total laryngectomy represents second primary tumors.  相似文献   
146.
Lactation is known to be associated with a transient loss of bone mineral density (BMD) during 3-6 months post-partum. Bone changes during lactation in women consuming low dietary calcium are not sufficiently studied. The present longitudinal study examined the BMD changes during lactation in undernourished women and the relationship of bone changes to the nutritional status. Whole-body bone mineral content and BMD at hip, lumbar spine and forearm were assessed using dual-energy X-ray absorptiometry in thirty-six lactating women from the low socio-economic group at four time points -- within 1 month after delivery (baseline), and at 6, 12 and 18 months after delivery. Maternal body composition and biochemical parameters of bone metabolism were estimated at the same time. It was observed that femoral neck BMD reduced by 4.6 % at 6 months, but recovery to the baseline was incomplete at 18 months with a deficit of 2 %. Hip BMD reduction at 6 months was transient. Lumbar spine BMD did not show significant loss at 6 months and BMD increased by 3.6 and 6.3 % at 12 and 18 months, respectively. Regression analyses indicated that baseline lean mass was the most important determinant of bone preservation at femoral neck, hip as well as whole body, whereas baseline body weight was the most important determinant of per cent gain in lumbar spine. Maternal nutritional status as indicated by body weight and lean mass appears to influence the lactation-related BMD changes in undernourished women from the low socio-economic group in India.  相似文献   
147.
148.
Cortical grey matter volume and sensorimotor gating in schizophrenia   总被引:2,自引:0,他引:2  
Prepulse inhibition (PPI) of the startle response, a cross-species measure of sensorimotor gating, provides a valuable tool to study the known inability of a large proportion of individuals with schizophrenia to effectively screen out irrelevant sensory input. The cortico-striato-pallido-thalamic circuitry is thought to be responsible for modulation of PPI in experimental animals. The involvement of this circuitry in human PPI is supported by observations of deficient PPI in a number of neuropsychiatric disorders that are characterised by abnormalities at some level in this circuitry, and findings of recent functional neuroimaging studies in healthy participants. The current study sought to investigate the structural neural correlates of PPI in a sample of 42 stable male outpatients with schizophrenia. Participants underwent magnetic resonance imaging (MRI) at 1.5T and were assessed (off-line) on acoustic PPI using electromyographic recordings of the orbicularis oculi muscle beneath the right eye. Optimised volumetric voxel-based morphometry implemented in SPM2 was used to investigate the relationship of PPI (prepulse onset-to-pulse onset interval 120msec) to regional grey matter (GM) volumes. Significant positive correlations were obtained between PPI and GM volume in the dorsolateral prefrontal, middle frontal and the orbital/medial prefrontal cortices. Our findings are consistent with (a) previous suggestions of susceptibility of PPI to cognitive processes controlled in a 'top down' manner by the cortex and (b) the hypothesis that compromised neural resources in the frontal cortex contribute to reduced PPI in schizophrenia.  相似文献   
149.
The frontal lobe has an extended maturation period and may be vulnerable to the long-term effects of schizophrenia. We tested this hypothesis by studying the relationship between duration of illness (DoI), grey matter (GM) and cerebro-spinal fluid (CSF) volume across the whole brain. Sixty-four patients with schizophrenia and 25 healthy controls underwent structural MRI scanning and neuropsychological assessment. We performed regression analyses in patients to examine the relationship between DoI and GM and CSF volumes across the whole brain, and correlations in controls between age and GM or CSF volume of the regions where GM or CSF volumes were associated with DoI in patients. Correlations were also performed between GM volume in the regions associated with DoI and neuropsychological performance. A longer DoI was associated with lower GM volume in the left dorsomedial prefrontal cortex (PFC), right middle frontal cortex, left fusiform gyrus (FG) and left cerebellum (lobule III). Additionally, age was inversely associated with GM volume in the left dorsomedial PFC in patients, and in the left FG and CSF excess near the left cerebellum in healthy controls. Greater GM volume in the left dorsomedial PFC was associated with better working memory, attention and psychomotor speed in patients. Our findings suggest that the right middle frontal cortex is particularly vulnerable to the long-term effect of schizophrenia illness whereas the dorsomedial PFC, FG and cerebellum are affected by both a long DoI and aging. The effect of illness chronicity on GM volume in the left dorsomedial PFC may be extended to brain structure-neuropsychological function relationships.  相似文献   
150.
Altered signals in magnetic resonance imaging are present in most symptomatic patients with neurologic manifestations of Wilson's disease. The changes primarily involve the basal ganglia, but they can be diverse and can involve a host of other structures. We describe a 12-year-old boy with Wilson's disease who manifested prominent white-matter cystic changes. These changes can cause diagnostic confusion, and may also present prognostic implications.  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