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   1718篇
  免费   66篇
  国内免费   6篇
耳鼻咽喉   30篇
儿科学   52篇
妇产科学   54篇
基础医学   178篇
口腔科学   211篇
临床医学   78篇
内科学   335篇
皮肤病学   27篇
神经病学   185篇
特种医学   16篇
外科学   299篇
综合类   5篇
预防医学   121篇
眼科学   25篇
药学   106篇
  1篇
中国医学   25篇
肿瘤学   42篇
  2024年   4篇
  2023年   13篇
  2022年   25篇
  2021年   48篇
  2020年   33篇
  2019年   45篇
  2018年   47篇
  2017年   36篇
  2016年   43篇
  2015年   47篇
  2014年   59篇
  2013年   97篇
  2012年   157篇
  2011年   187篇
  2010年   102篇
  2009年   77篇
  2008年   121篇
  2007年   138篇
  2006年   135篇
  2005年   104篇
  2004年   80篇
  2003年   68篇
  2002年   62篇
  2001年   11篇
  2000年   9篇
  1999年   8篇
  1998年   7篇
  1997年   3篇
  1996年   2篇
  1995年   1篇
  1994年   2篇
  1993年   1篇
  1992年   2篇
  1991年   1篇
  1990年   2篇
  1988年   1篇
  1987年   1篇
  1985年   2篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1978年   1篇
  1942年   1篇
  1914年   1篇
  1907年   1篇
排序方式: 共有1790条查询结果,搜索用时 15 毫秒
81.
BACKGROUND: Alcohol intake and tobacco smoke, in addition to other environmental and genetic factors, have been associated with head and neck cancer. We evaluated the role of metabolic enzyme polymorphisms on the risk of head and neck cancer in a hospital-based case-control study. METHODS: CYP1A1MspI, CYP2E1PstI, GSTM1, and GSTT1polymorphisms were evaluated in 103 histologically confirmed head and neck cancer cases and 102 controls by means of polymerase chain reaction-restriction fragment length polymorphism methods. RESULTS: GSTM1null increased the risk of head and neck cancer (odds ratio [OR], 2.2; 95% confidence interval [95% CI], 1.24-3.79), oral cancer (OR, 2.8; 95% CI, 1.28-5.98), and pharyngeal cancer (OR, 2.2; 95% CI, 1.08-4.63). CYP2E1PstI polymorphism indicated a risk for oral cancer (OR, 3.6; 95% CI, 1.29-11.56). The joint effect of GSTM1 null and CYP1A1 polymorphism increased the risk of head and neck cancer (OR, 2.4; 95% CI, 1.13-5.10). CONCLUSIONS: GSTM1 null alone or associated with CYP1A1 increased the risk of head and neck cancer; the CYP2E1PstI mutated allele increased the risk for only oral cancer.  相似文献   
82.

Introduction

Anatomical and functional influences on gastric bypass (GBP) results are often poorly evaluated and not yet fully understood.

Purpose

The purpose of this study is to evaluate the influence of the gastric pouch volume and its emptying rate on long-term weight loss and food tolerance after GBP.

Materials and Methods

Weight loss, food tolerance, pouch volumetry (V) by three-dimensional reconstruction, and pouch emptying rate by 4 h scintigraphy were evaluated in 67 patients. Cutoffs were identified for V and retention percentage (%Ret) at 1 h (%Ret1). From these parameters, the sample was categorized, looking for associations between V, %Ret, weight loss, and food tolerance, assessed by a questionnaire for quick assessment of food tolerance (SS).

Results

PO median follow-up time was 47 months; median V was 28 mL; %Ret at 1, 2, and 4 h were 8, 2, and 1%, respectively. There were associations between V ≤ 40 mL and higher emptying rates up to 2 h (V ≤ 40 mL: %Ret1 = 6, %Ret2 = 2, p = 0.009; V > 40 mL: %Ret1 = 44, %Ret2 = 13.5, p = 0.045). An association was found between higher emptying speed in 1 h and higher late weight loss (WL), represented by lower percentage of excess weight loss (%EWL) regain (p = 0.036) and higher %EWL (p = 0.033) in the group with %Ret1 ≤ 12%, compared to the group %Ret1 ≥ 25%. Better food tolerance (SS > 24), was associated with lower %Ret1 (p = 0.003).

Conclusion

Smaller pouch size is associated with a faster gastric emptying, greater WL maintenance, and better food tolerance. These data suggest that a small pouch with rapid emptying rate is an important technical parameter for good outcomes in GBP.
  相似文献   
83.
Most mediastinal abscesses result from infections after thoracotomy, esophageal perforation or penetrating chest trauma. This disease is rarely caused by closed blunt chest trauma. All previously reported such cases after closed blunt chest trauma presented with hematoma and sternal osteomyelitis resulting from sternal fracture. Here we report a 15-year-old sumo wrestler who presented with an anterior mediastinal abscess without any mediastinal fracture. The mediastinal abscess resulted from the hematogenous spread of Staphylococcus aureus to a hematoma that might have been caused by a closed blunt chest trauma incurred during sumo wrestling exercises.  相似文献   
84.
Neurosurgical Review - Cellular response to TBI is a mixture of excitotoxicity, neuroinflammation, and cell death. Biomarkers that can track these lesions and inflammatory processes are being...  相似文献   
85.
Parkinson's disease (PD) is characterised by motor alterations, which are commonly treated with L-DOPA. However, long-term L-DOPA use may cause dyskinesia. Although the pathogenic mechanism of L-DOPA-induced dyskinesia is unclear, the condition has been associated with alterations in dopamine receptors, among which D2 receptors (D2R) have received little attention. This study aims to: (i) develop and standardise an experimental model of L-DOPA-induced dyskinesia in rats with hemiparkinsonism; and (ii) evaluate the correlation between D2R expression and presence of abnormal involuntary movements (AIM). We allocated 21 male Wistar rats into 3 groups: intact controls, lesioned rats (with neurotoxin 6-OHDA), and dyskinetic rats (injected with L-DOPA for 19 days). Sensorimotor impairment was assessed with behavioural tests. Dyskinetic rats gradually developed AIMs during the treatment period; front leg AIMs were more severe and locomotor AIMs less severe (P < .05). All AIMs were significantly evident from day 5 and persisted until the last day of injection. D2R density was greater in the striatum and the medial anterior brain of the lesioned and dyskinetic rats than in those of controls. Our results suggest an association between D2R expression and locomotor AIMs. We conclude that RD2 is involved in L-DOPA-induced dyskinesia.  相似文献   
86.

Objective

To investigate the Bereitschaftspotential (BP) preceding spontaneous and voluntary eyelid blinks in normal subjects.

Methods

Eighteen healthy individuals (10 female) between 17 and 60 years (mean 35) were studied. The EEG was recorded from 11 scalp positions of the 10–20 international electrode placement system referenced to linked mastoids. The vertical electrooculogram (VEOG) was recorded from two electrodes positioned above and below the right eye. The ground electrode was placed in the right clavicle. The recordings were obtained during spontaneous and voluntary eyelid blinks. Two-second EEG segments before the onset of the blink potential (visually identified at the VEOG channel) were averaged and analyzed off-line. The statistical significance of differences was evaluated by repeated-measures analysis of variance with Geisser–Greenhouse correction for violation of sphericity and the Newman–Keuls test was used for post hoc comparisons.

Results

A BP starting around ?1700 ms prior to the onset of voluntary blink was observed; it had average amplitude in the negative peak of 3.3 μV. There was no BP preceding spontaneous blinking.

Conclusion

A BP precedes voluntary blinks but not spontaneous blinks.

Significance

This is the first study evaluating the BP preceding spontaneous and voluntary eye blinks.  相似文献   
87.
A five-and-a-half-year-old girl started experiencing progressive left hemiparesis at age two and a half years. At age five years and four months she started presenting clusters of asymmetric periodic epileptic spasms with no hypsarrhythmia. The ictal EEG showed periodic, constant and stereotyped complexes. Serial brain imaging revealed progressive atrophy of the right hemisphere with increased T2 signal on MRI. She underwent a right hemispherotomy, and histological examination showed signs of inflammation and features of focal cortical dysplasia (FCD). She has been seizure-free for 16 months. This case is unique in the following aspects: the presence of typical Rasmussen encephalitis features of progressive unilateral brain involvement without seizures, a delay of almost three years prior to seizure onset; an atypical seizure type presentation with periodic epileptic spasms and the presence of FCD associated with inflammatory changes. [Published with video sequences].  相似文献   
88.

Introduction  

Cysticercosis (CC) is the most important of the parasitic diseases of the central nervous system due to its high incidence in the world. CC is the infection with the larval cysts of Taenia solium. It is the most common helminthic infection of the nervous system and is endemic in most underdeveloped countries as well as in industrialized nations. It is estimated that approximately 50,000 people die every year from neurocysticercosis (NCC) worldwide.  相似文献   
89.
90.
The purpose of this study was to determine the epidemiology and control of hospital-acquired infections (HAI) in paediatric surgery. We reviewed 2844 hospitalized children in a paediatric surgical clinic between January 1997 and December 2000. The diagnosis of HAI was made based on criteria proposed by Centers for Disease Control and Prevention (CDC). The incidence, type of micro-organisms and infections, age, sex, risk factors, and the economic aspects were recorded. The mortality, duration of hospitalization and economic aspects of patients were compared with 78 control patients matured for age, sex and primary illness and free of HAI. There were 78 children with HAI, the overall incidence was 2.74% (4.99% in 1997, 3.89% in 1998, 1.33% in 1999, 1.44% in 2000). The most frequent infections were surgical wound (28 patients) and urinary tract (25 patients). The most frequent risk factors were urethral catheterization (10.26%), trauma (9.25%), and parenteral nutrition (8.70%). Mean hospitalization was 16 days (range 4-28 days) in patients with infection compared with nine days (range 2-22 days) in control group. Eight patients died in the infection group, while two died in the control group. HAI caused a significant increase in mortality, prolonged hospitalization and increased costs (P < 0.05, P < 0.001, P < 0.001, respectively).  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