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   776篇
  免费   26篇
  国内免费   2篇
耳鼻咽喉   6篇
儿科学   36篇
妇产科学   9篇
基础医学   97篇
口腔科学   13篇
临床医学   55篇
内科学   192篇
皮肤病学   13篇
神经病学   76篇
特种医学   30篇
外科学   127篇
综合类   12篇
预防医学   15篇
眼科学   3篇
药学   62篇
中国医学   3篇
肿瘤学   55篇
  2022年   5篇
  2021年   16篇
  2020年   7篇
  2018年   17篇
  2017年   6篇
  2016年   9篇
  2015年   6篇
  2014年   13篇
  2013年   23篇
  2012年   38篇
  2011年   34篇
  2010年   33篇
  2009年   34篇
  2008年   31篇
  2007年   28篇
  2006年   35篇
  2005年   34篇
  2004年   35篇
  2003年   18篇
  2002年   23篇
  2001年   16篇
  2000年   22篇
  1999年   21篇
  1998年   9篇
  1997年   16篇
  1996年   9篇
  1995年   8篇
  1994年   5篇
  1993年   16篇
  1992年   10篇
  1991年   19篇
  1990年   24篇
  1989年   12篇
  1988年   19篇
  1987年   13篇
  1986年   16篇
  1985年   18篇
  1984年   6篇
  1983年   7篇
  1982年   8篇
  1981年   4篇
  1980年   6篇
  1979年   7篇
  1978年   4篇
  1972年   4篇
  1971年   5篇
  1970年   9篇
  1968年   4篇
  1967年   6篇
  1965年   6篇
排序方式: 共有804条查询结果,搜索用时 15 毫秒
21.
Increased density of γ/δ T cell receptor (TCR)+ intraepithelial lymphocytes is the only characteristic in the jejunum of patients with coeliac disease and dermatitis herpetiformis which is not normalized on a gluten-free diet. We explored the age-dependent changes in intraepithelial γ/δ and α/β TCR+ cells from 137 biopsies from patients with coeliac disease and dermatitis herpetiformis and from controls. Biopsy specimens from 100 patients with coeliac disease and dermatitis herpetiformis and from 37 controls were studied with an immunohistochemical method using MoAbs to T cell receptors and peroxidase staining. An increase in the density of intraepithelial γ/δ T cells above the mean +2 s.d. of the density in controls was present in 97 of 100 specimens from patients with coeliac disease and dermatitis herpetiformis. The density of γ/δ+ cells of patients with coeliac disease and dermatitis herpetiformis on a normal gluten-containing diet showed a positive correlation with age (r = 0.45, P< 0.0001). In controls, the density of γ/δ+ cells remained low throughout the age-range studies, from age 0.6–57 years. In controls, α/β+ cells increased with age (r = 0.57, P< 0.001). The increase in density of intraepithelial lymphocytes with age is in agreement with their thymus-independent character and local proliferation.  相似文献   
22.
To investigate the pulmonary haemodynamic effects of meconium aspiration and subsequent adenosine triphosphate (ATP) treatment, 12 anaesthetized and ventilated pigs (wt 24-28 kg) received either ATP or an equal volume of saline into the right heart in doses of 0.02 to 0.80 lmol kg-1 min?1 after intratracheal administration of 2 mL kg?1 of human meconium. Meconium instillation induced significant increases in pulmonary vascular pressures and total and postarterial resistances calculated from pulmonary artery occlusion studies, but did not affect the systemic haemodynamics, except for a fall in heart rate and increase in central venous pressure. Infusion of ATP at the lowest doses (0.02 and 0.08 µmol kg?1 min?1) selectively decreased the pulmonary arterial pressure and vascular resistance and at 0.32 and 0.80 µmol kg?1 min?1 reduced both the pulmonary and systemic resistances. In the lung circulation the increasing doses of ATP reduced preferably the arterial, but also the postarterial resistance. Withdrawal of ATP infusion led to a significant rebound effect especially in the postarterial segment of the lung circulation. Meconium aspiration thus induces an acute, predominantly postarterial obstruction in the lung circulation and infusion of ATP at low doses selectively dilates the pulmonary vascular bed and may help to preclude elevation of capillary pressures in meconium aspiration-induced pulmonary hypertension.  相似文献   
23.
Several lines of evidence show that transplantation of osteoblastic cells or genetically engineered nonosteogenic cells expressing osteoblast‐related genes into bone defects effectively promotes bone regeneration. To extend this possibility, we investigated whether oral mucosal fibroblasts are capable of differentiating into osteoblastic cells by conducting in vitro and in vivo experiments. We investigated the effects of bone morphogenetic protein‐2 (BMP‐2) on osteoblast differentiation of cultured fibroblasts isolated from canine buccal mucosa. We also transplanted green fluorescence protein (GFP)‐expressing fibroblasts with gelatin/BMP‐2 complexes into the subfascial regions of athymic mice, and investigated the localization of GFP‐positive cells in the ectopically formed bones. The cultured canine buccal mucosal fibroblasts differentiated into osteoblastic cells by increasing their alkaline phosphatase (ALP) activity and Osteocalcin, Runx2, and Osterix mRNA expression levels in response to BMP‐2. Transplantation experiments of GFP‐expressing oral mucosal fibroblasts with gelatin/BMP‐2 complexes revealed that 17.1% of the GFP‐positive fibroblasts differentiated into ALP‐positive cells, and these cells accounted for 6.2% of total ALP‐positive cells in the ectopically formed bone. This study suggests that oral mucosal fibroblasts can differentiate into osteogenic cells in response to BMP‐2. Thus, these cells are potential candidates for cell‐mediated bone regeneration therapy in dentistry. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.  相似文献   
24.
Clinical Autonomic Research - Delayed orthostatic hypotension (DOH), a fall in blood pressure after a 3-min cutoff, is clinically meaningful. The aim of this study was to elucidate the clinical and...  相似文献   
25.
Introduction: We examined whether quantification of T-wave alternans (TWA) enhances this parameter's capacity to evaluate the risk for total and cardiovascular mortality and sudden cardiac death (SCD).
Methods and Results: The Finnish Cardiovascular Study (FINCAVAS) enrolled consecutive patients (n = 2,119; 1,342 men and 777 women) with a clinically indicated exercise test with bicycle ergometer. TWA (time domain-modified moving average method) was analyzed from precordial leads, and the results were grouped in increments of 10 μV. Hazard ratios (HR) for total and cardiovascular mortality and SCD were estimated for preexercise, routine exercise, and postexercise stages. Cox regression analysis was performed. During follow-up of 47.1 ± 12.9 months (mean ± standard deviation [SD]), 126 patients died: 62 were cardiovascular deaths, and 33 of these deaths were sudden. During preexercise, TWA ≥ 20 μV predicted the risk for total and cardiovascular mortality (maximum HR >4.4 at 60 μV, P < 0.02 for both). During exercise, HRs of total and cardiovascular mortality were significant when TWA measured ≥50 μV, with 90 μV TWA yielding maximum HRs for total and cardiovascular death of 3.1 (P = 0.03) and 6.4 (P = 0.002), respectively. During postexercise, TWA ≥60 μV indicated risk for total and cardiovascular mortality, with maximum HR of 3.4 at 70 μV (P = 0.01) for cardiovascular mortality. SCD was strongly predicted by TWA levels ≥60 μV during exercise, with maximum HR of 4.6 at 60 μV (P = 0.002), but was not predicted during pre- or postexercise.
Conclusion: Quantification of TWA enhances its capacity for determination of the risk for total and cardiovascular mortality and SCD in low-risk populations. Its prognostic power is superior during exercise compared to preexercise or postexercise.  相似文献   
26.
We report a case of torsion of an accessory lobe of the liver (ALL) in a 14-year-old girl. The patient was admitted for acute abdominal pain and laparotomy revealed an ALL, the pedicle of which was elongated with 180° torsion. The diagnosis was not made preoperatively because of the rarity of this condition. However, a close relationship between omphalocele repair and the development of ALL has been reported; thus, a history of omphalocele repair should alert the doctor to the possibility of this condition, which could be suggested by imaging findings preoperatively. Torsion of an ALL should be included in the differential diagnosis of a patient with a history of omphalocele, who presents with acute abdominal symptoms.  相似文献   
27.
A girl aged 1 year 9 months had recurrent episodes of febrile status epilepticus. She recovered completely after the first three episodes. However, at 9 months she developed acute encephalopathy resulting in severe neurologic sequelae. Diffusion‐weighted magnetic resonance imaging revealed diffuse high‐intensity signals over the cortex and subcortical white matter in the acute phase and severe diffuse cerebral atrophy in the chronic phase. Mutations were detected in the neuronal voltage‐gated sodium channel alpha subunit type 1 (SCN1A) gene. SCN1A sequence analysis revealed a truncation mutation: ex1‐c.126Adel (D43fs). Our patient was likely afflicted by severe myoclonic epilepsy in infancy, and the fourth episode of status epilepticus was similar to acute encephalopathy. This report provides further insight into the molecular pathophysiology underlying acute encephalopathy.  相似文献   
28.
In August 2002 the Japanese Society of Psychiatry and Neurology decided to rename the Japanese expression for schizophrenia from Sêshin Bunretsu By? to T?g? Shicch? Sh?. Currently the psychiatric classification systems ICD-10 and DSM-IV are under revision. Against this background the Japanese process of renaming a psychiatric disorder is of high interest as far as the clinical, social and cultural implications of the new name are concerned.The authors give an overview of the Japanese process of renaming schizophrenia. Its background and realization are explained and the expectations of Japanese physicians, patients and their families related to the new name are analysed. Furthermore, its effects are evaluated. The aim of the paper is to clarify in how far the Japanese example may serve as a model for evaluating the possible implications that a renaming or nosological redefinition of schizophrenia might have in the course of the revision process of ICD 10 and DSM IV.  相似文献   
29.
The function of jejunal intraepithelial gamma delta+ T cells is obscure, but they are commonly implicated as playing a role in inflammatory and autoimmune conditions. In coeliac disease (CoD), there are controversial reports as to gluten dependency of these cells. We have now studied the small bowel mucosal intraepithelial T cell densities, and the ratios of gamma delta+ to CD3+ T cells and gamma delta+ to alpha beta+ T cells during early disease development and on a gluten-free diet. Nine children initially excluded for CoD were followed up and rebiopsy after 0.8-4.5 years showed mucosal deterioration. Further, 21 biopsy specimens from newly diagnosed CoD patients were studied, together with 20 specimens taken from children on a gluten-free diet. During CoD development the density of gamma delta+ and alpha beta+ T cells as well as the ratios of gamma delta+ to CD3+ T cells and gamma delta+ to alpha beta+ T cells increased. In the latent stage of CoD when the small bowel mucosal architecture was still normal, two children had clearly normal densities of gamma delta+ (< 2.5 cells/100 epithelial cells) and alpha beta+ (< 25.0 cells/100 epithelial cells) T cells, and low ratios as well. In patients with newly diagnosed CoD the densities decreased significantly on a long-term gluten-free diet. We conclude that the density of intraepithelial gamma delta+ T cells as well as alphabeta+ T cells in CoD is gluten-dependent. CoD can develop in a child ingesting normal amounts of gluten and having normal jejunal mucosal morphology on biopsy and a normal density of gamma delta+ T cells.  相似文献   
30.
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