全文获取类型
收费全文 | 3932篇 |
免费 | 96篇 |
国内免费 | 40篇 |
专业分类
耳鼻咽喉 | 152篇 |
儿科学 | 15篇 |
妇产科学 | 11篇 |
基础医学 | 775篇 |
口腔科学 | 152篇 |
临床医学 | 254篇 |
内科学 | 110篇 |
皮肤病学 | 6篇 |
神经病学 | 651篇 |
特种医学 | 200篇 |
外科学 | 970篇 |
综合类 | 341篇 |
预防医学 | 52篇 |
眼科学 | 72篇 |
药学 | 184篇 |
1篇 | |
中国医学 | 44篇 |
肿瘤学 | 78篇 |
出版年
2023年 | 86篇 |
2022年 | 134篇 |
2021年 | 188篇 |
2020年 | 114篇 |
2019年 | 118篇 |
2018年 | 115篇 |
2017年 | 107篇 |
2016年 | 115篇 |
2015年 | 98篇 |
2014年 | 194篇 |
2013年 | 182篇 |
2012年 | 186篇 |
2011年 | 190篇 |
2010年 | 161篇 |
2009年 | 153篇 |
2008年 | 154篇 |
2007年 | 140篇 |
2006年 | 134篇 |
2005年 | 105篇 |
2004年 | 94篇 |
2003年 | 78篇 |
2002年 | 65篇 |
2001年 | 56篇 |
2000年 | 65篇 |
1999年 | 67篇 |
1998年 | 46篇 |
1997年 | 48篇 |
1996年 | 50篇 |
1995年 | 45篇 |
1994年 | 33篇 |
1993年 | 45篇 |
1992年 | 32篇 |
1991年 | 36篇 |
1990年 | 37篇 |
1989年 | 32篇 |
1988年 | 42篇 |
1987年 | 55篇 |
1986年 | 33篇 |
1985年 | 51篇 |
1984年 | 40篇 |
1983年 | 19篇 |
1982年 | 38篇 |
1981年 | 31篇 |
1980年 | 36篇 |
1979年 | 38篇 |
1978年 | 30篇 |
1977年 | 25篇 |
1976年 | 23篇 |
1975年 | 21篇 |
1973年 | 29篇 |
排序方式: 共有4068条查询结果,搜索用时 15 毫秒
1.
《Clinical neurophysiology》2021,132(9):2003-2011
ObjectiveA large N20 and P25 of the median nerve somatosensory evoked potential (SEP) predicts short survival in amyotrophic lateral sclerosis (ALS). We investigated whether high frequency oscillations (HFOs) over N20 are enlarged and associated with survival in ALS.MethodsA total of 145 patients with ALS and 57 healthy subjects were studied. We recorded the median nerve SEP and measured the onset-to-peak amplitude of N20 (N20o-p), and peak-to-peak amplitude between N20 and P25 (N20p-P25p). We obtained early and late HFO potentials by filtering SEP between 500 and 1 kHz, and measured the peak-to-peak amplitude. We followed up patients until endpoints (death or tracheostomy) and analyzed the relationship between SEP or HFO amplitudes and survival using a Cox analysis.ResultsPatients showed larger N20o-p, N20p-P25p, and early and late HFO amplitudes than the control values. N20p-P25p was associated with survival periods (p = 0.0004), while early and late HFO amplitudes showed no significant association with survival (p = 0.4307, and p = 0.6858, respectively).ConclusionsThe HFO amplitude in ALS is increased, but does not predict survival.SignificanceThe enlarged HFOs in ALS might be a compensatory phenomenon to the hyperexcitability of the sensory cortex pyramidal neurons. 相似文献
2.
ObjectiveTo determine if individuals with chronic ankle instability (CAI) demonstrate altered landing kinematics, muscle activity, and impaired dynamic postural stability during a unilateral jump-landing task.Methods21 studies were included from PubMed, MEDLINE, Embase and CINAHL searched on September 26, 2021. Mean differences in joint angles and muscle activity between CAI and controls were analysed as continuous variables and pooled using a random-effects model to obtain standardised mean differences and 95% confidence intervals. Dynamic postural stability measured using time to stabilisation (TTS) was assessed qualitatively.ResultsWe found greater plantarflexion (pooled SMD = 0.33, 95%CI [0.02,0.65]), reduced knee flexion (pooled SMD = −0.67, 95%CI [−0.97, −0.37]), and reduced hip flexion (pooled SMD = −0.52, 95%CI [−0.96, −0.07]) in CAI after landing. Regarding muscle activity, we observed reduced peroneus longus muscle activation (pooled SMD = −0.77, 95% CI [−1.17, −0.36]) in CAI prior to landing.ConclusionOur study provides preliminary evidence of altered landing kinematics in the sagittal plane and reduced peroneus muscle activity in CAI during a dynamic jump-landing task. These results may have clinical implications in the development of more effective and targeted rehabilitation programmes for patients with CAI. 相似文献
3.
4.
Over the past 20 years there has been a growing interest in the neural underpinnings of cost/benefit decision-making. Recent studies with animal models have made considerable advances in our understanding of how different prefrontal, striatal, limbic and monoaminergic circuits interact to promote efficient risk/reward decision-making, and how dysfunction in these circuits underlies aberrant decision-making observed in numerous psychiatric disorders. This review will highlight recent findings from studies exploring these questions using a variety of behavioral assays, as well as molecular, pharmacological, neurophysiological, and translational approaches. We begin with a discussion of how neural systems related to decision subcomponents may interact to generate more complex decisions involving risk and uncertainty. This is followed by an overview of interactions between prefrontal-amygdala-dopamine and habenular circuits in regulating choice between certain and uncertain rewards and how different modes of dopamine transmission may contribute to these processes. These data will be compared with results from other studies investigating the contribution of some of these systems to guiding decision-making related to rewards vs. punishment. Lastly, we provide a brief summary of impairments in risk-related decision-making associated with psychiatric disorders, highlighting recent translational studies in laboratory animals. 相似文献
5.
IntroductionCentral venous catheter applications and complications are closely related to the tip position. Previous studies have reported some rare cases of catheter misplacement. Here, we report a case of misplacement of a peripherally inserted central catheter into the lateral thoracic vein.Case reportA 56-year-old cancer patient underwent placement of a peripherally inserted central catheter through the left basilic vein under ultrasound-guided puncture. The catheterisation procedure was uneventful, so the catheter was believed to be in the superior vena cava. However, the post-anterior chest X-ray image revealed that after the catheter advanced towards the axilla, it turned downwards and outwards in the direction of the left lateral thoracic region, with the projection of the catheter tip giving the appearance of termination in the subcutaneous tissue of the lateral thoracic wall on the two-dimensional image. The catheter was then repositioned in the distal superior vena cava.DiscussionPeripherally inserted central catheters can be potentially misplaced into the lateral thoracic vein because these catheters can pass through the orifice of the lateral thoracic vein which flows into the axillary vein. Some pathological cases and clinical conditions can cause dilatation of the lateral thoracic vein, which increases the probability of catheter misplacement. Three principles were proposed to avoid this rare complication: a comprehensive review of the patients’ medical history, real-time image-guided catheterisation and routine radiographic identification of the tip position. 相似文献
6.
Bone stock preservation is crucial when performing total hip replacement in young patients. The aim is to save good bone stock
for a possible revision procedure. Furthermore, there is an increasing demand from young and active patients to receive a
new joint which allows a normal or nearly normal life style. With this in mind, we began, in 1993, to develop a new femoral
implant. The purpose of this ultra-short stem was a physiologic strain distribution on the proximal femur with a proximal
load transfer from the implant to the femoral bone. Main features were an almost complete absence of the diaphyseal portion
of the stem, a well defined lateral flare with load transfer on the lateral column of the femur, and a very high femoral neck
cut. These innovations resulted in a conservative implant on both the bone stock and the soft tissues. This implant, in the
first years, was recommended only for young and active patients. Over the last thirteen years, this project has undergone
several modifications but the basic principles of the implant have remained the same. In the present review, we present the
rationale, the surgical technique and the clinical and experimental results so far obtained with this implant. 相似文献
7.
8.
目的探讨直接数字化X线摄影(direct digitized radiography,DDR)在腰椎侧位影像中的应用价值。方法随机抽取81例患者的DDR腰椎侧位影像,使用图像后处理方法中多级图像对比增益法,又称“交响乐”功能(multi—scale image contrast amplification,MUSICA)进行后处理,同时取另81例患者进行普通X线摄影,由放射科经验丰富的医生、技师各2名对所有的腰椎侧位影像进行分析,采用常规影像质量评价指标评价两组的影像质量。结果(1)DDR腰椎侧位影像质量影像评分为13.00,普通X线影像评分为8.96,经非参数检验的配对符号秩和检验,依赖负秩计算的统计量(X^2=-7.88,P〈0.01),两组差异有统计学意义,DDR腰椎侧位组明显优于普通平片组;(2)81例中DDR腰椎图像显示满意率为92.6%(75/81),普通X线平片显示满意率为61.7%(50/81),两者差异有统计学意义(X^2=21.89,P〈0.01)。结论与普通X线影像相比,DDR影像能更好的显示下部腰椎椎体、附件及周围软组织,可获得良好的图像,有利于放射诊断工作。 相似文献
9.
Sérgio Carreir?o Leandro Pereira Marcelo Wilson Rocha Almeida 《Aesthetic plastic surgery》2009,33(3):445-451
Surgical procedures for the mammary region currently are assuming an important role in body-contouring surgery. Enhancement
of results is a constant challenge to the plastic surgeon. A simple and efficient maneuver for resection of the breast’s lateral
pole based on the mammoplasty technique of Professor Ivo Pitanguy is described.
This study realized at the Private Clinic Sérgio Carreir?o, Rio de Janeiro, RJ, Brazil. 相似文献
10.
梗阻性脑积水侧脑室及室周脑组织生物力学响应的有限元分析 总被引:1,自引:0,他引:1
目的运用有限元方法对梗阻性脑积水进行计算机模拟,研究分析侧脑室及室周脑组织的生物力学响应及其所产生的病理生理影响。方法依据正常国人颅脑MRI轴位T2加权图像获取解剖信息,在有限元软件ANSYS中生成包含侧脑室前、后角和体部的半侧脑层面的二维有限元模型。模拟脑组织为固、液两相物质组成的线性多孔弹性材料,设定生物力学特性参数及边界条件和初始条件,施加载荷,运用有限元软件ABAQUS进行计算求解,以云图形式输出结果。结果有限元模型动态模拟了梗阻性脑积水侧脑室各部的扩张过程,直观显示出各个时间步室周脑组织内的应力类型及分布、各部的应变和位移。结论膨胀性应力集中引起角部脑水肿;梗阻性脑积水早期侧脑室角部形态变化最明显;体部附近脑组织结构容易受压移位。这些生物力学响应是室内压增高的结果,也与侧脑室的解剖形态密切相关。 相似文献