全文获取类型
收费全文 | 883篇 |
免费 | 32篇 |
国内免费 | 78篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 42篇 |
妇产科学 | 7篇 |
基础医学 | 95篇 |
口腔科学 | 15篇 |
临床医学 | 143篇 |
内科学 | 178篇 |
皮肤病学 | 22篇 |
神经病学 | 15篇 |
特种医学 | 286篇 |
外科学 | 38篇 |
综合类 | 20篇 |
预防医学 | 26篇 |
眼科学 | 1篇 |
药学 | 76篇 |
肿瘤学 | 28篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 8篇 |
2015年 | 11篇 |
2014年 | 17篇 |
2013年 | 18篇 |
2012年 | 15篇 |
2011年 | 5篇 |
2010年 | 23篇 |
2009年 | 34篇 |
2008年 | 13篇 |
2007年 | 60篇 |
2006年 | 5篇 |
2005年 | 20篇 |
2004年 | 7篇 |
2003年 | 15篇 |
2002年 | 9篇 |
2001年 | 17篇 |
2000年 | 13篇 |
1999年 | 19篇 |
1998年 | 66篇 |
1997年 | 72篇 |
1996年 | 50篇 |
1995年 | 62篇 |
1994年 | 36篇 |
1993年 | 35篇 |
1992年 | 16篇 |
1991年 | 18篇 |
1990年 | 13篇 |
1989年 | 34篇 |
1988年 | 33篇 |
1987年 | 23篇 |
1986年 | 26篇 |
1985年 | 43篇 |
1984年 | 18篇 |
1983年 | 12篇 |
1982年 | 25篇 |
1981年 | 14篇 |
1980年 | 24篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 14篇 |
1976年 | 15篇 |
1975年 | 9篇 |
1970年 | 1篇 |
排序方式: 共有993条查询结果,搜索用时 265 毫秒
921.
目的: 剪切应力是血液在血管内流动时对内皮细胞产生的一种机械刺激, 一定程度的剪切应力对于维持血管的正常结构和功能十分重要. ICAM-1是血管内皮细胞等产生的一类免疫球蛋白超家族粘附分子, 除介导免疫、炎症反应及细胞间粘附和连接外, 还能传递多种细胞信号, 引起细胞内骨架蛋白结构与功能的改变. 故此, 研究在不同剪切应力的作用下, 血管内皮细胞表面粘附分子ICAM-1分布的改变及其机制. 方法: 将ECV304细胞常规培养在长方形的玻片上, 然后分别置于剪切应力为0.2 Pa、 1 Pa(相当于正常状况下动脉血管内的剪切应力)、 2 Pa的流场中, 温度37 ℃. 4 h后取出玻片, 先用鼠抗人ICAM-1单克隆抗体(1∶20)孵育20 min, PBS冲洗, 再用标记有AlexaR荧光的羊抗鼠IgG(1∶50)作为二抗标记, 1%多聚甲醛和0.5% Triton-X100渗透和固定后, 在Olympus IX70荧光显微镜下观察ICAM-1的分布状况. 结果: 在正常状态下(1 Pa), ICAM-1主要分布在细胞间连接处, 而在较低剪切应力(0.2 Pa)和较高剪切应力(2 Pa)作用下, ICAM-1则呈现出细胞表面散在分布的特征. 结论: 过低或过高的剪切应力都会引起血管内皮细胞表面ICAM-1分布的改变. 相似文献
922.
Okolo C Franceschi S Adewole I Thomas JO Follen M Snijders PJ Meijer CJ Clifford GM 《Infectious agents and cancer》2010,5(1):24
Background
Concerns have been raised that the proportion of cervical cancer preventable by human papillomavirus (HPV) 16/18 vaccines might be lower in sub-Saharan Africa than elsewhere. 相似文献923.
O Morel E Monceau N Tran C Malartic F Morel E Barranger JF Côté E Gayat P Chavatte-Palmer D Cabrol V Tsatsaris 《BJOG : an international journal of obstetrics and gynaecology》2009,116(7):915-922
Objective To evaluate radiofrequency (RF) efficiency and safety for the ablation of retained placenta in humans, using a pregnant sheep model.
Design Experimental study.
Setting Laboratory of Surgery School, Nancy, France.
Population/sample Three pregnant ewes/ten human placentas.
Methods Various RF procedures were tested in pregnant ewes on 50 placentomes (individual placental units). Reproducibility of the best procedure was then evaluated in a further 20 placentomes and on ten human term placentas in vitro after delivery.
Main outcome measures Placental tissues destruction, lesions' size, myometrial lesions.
Results Low power (100 W) and low target temperatures (60°C) lead to homogenous tissue destruction, without myometrial lesion. No significant difference was observed in terms of lesion size and procedure duration for in the placentomes of pregnant ewe in vivo and in human placentas in vitro . The diameter of the ablation could be correlated with the tines deployment.
Conclusion The placental tissue structure is very permissive to RF energy, which suggests that RF could be used for the ablation of retained placenta, providing optimal control of tissue destruction. These results call for further experimental evaluations. 相似文献
Design Experimental study.
Setting Laboratory of Surgery School, Nancy, France.
Population/sample Three pregnant ewes/ten human placentas.
Methods Various RF procedures were tested in pregnant ewes on 50 placentomes (individual placental units). Reproducibility of the best procedure was then evaluated in a further 20 placentomes and on ten human term placentas in vitro after delivery.
Main outcome measures Placental tissues destruction, lesions' size, myometrial lesions.
Results Low power (100 W) and low target temperatures (60°C) lead to homogenous tissue destruction, without myometrial lesion. No significant difference was observed in terms of lesion size and procedure duration for in the placentomes of pregnant ewe in vivo and in human placentas in vitro . The diameter of the ablation could be correlated with the tines deployment.
Conclusion The placental tissue structure is very permissive to RF energy, which suggests that RF could be used for the ablation of retained placenta, providing optimal control of tissue destruction. These results call for further experimental evaluations. 相似文献
924.
The effect of apomorphine administration on smooth pursuit ocular movements in early Parkinsonian patients 总被引:3,自引:0,他引:3
Bares M Brázdil M Kanovský P Jurák P Daniel P Kukleta M Rektor I 《Parkinsonism & related disorders》2003,9(3):139-144
Electrooculography (EOG) recordings in 21 L-DOPA-naive patients suffering from Parkinson's disease (PD) were made before and after apomorphine subcutaneous administration (ASA). The effect of apomorphine on smooth pursuit eye movements (SPEM) was studied. Age-matched healthy subjects, who underwent SPEM recordings without the ASA procedure, were examined in order to compare baseline SPEM. EOG recordings were used to compare the patient group and the control group, and to compare the SPEM before and after ASA within the patient group. Significant differences in SPEM were found between both groups, as well as in the SPEM before and after ASA. The theory that SPEM is disturbed in early PD patients was confirmed. The dopaminergic control of horizontal SPEM is supposed. 相似文献
925.
Bladder cancer: staging with CT and MR imaging 总被引:10,自引:0,他引:10
Magnetic resonance (MR) imaging and computed tomography (CT) were compared in 30 patients with histologically proved bladder cancer. MR imaging was accurate in depicting the presence or absence of extravesical spread in 22 patients (accuracy, 73%; sensitivity, 82%; specificity, 62%), and CT was accurate in 24 patients (accuracy, 80%; sensitivity, 94%; specificity, 62%). The MR examinations of two patients were of undiagnostic quality and therefore considered to be technical failures. Each technique resulted in five false-positive and one false-negative examination for the diagnosis of extravesical tumor spread. In 28 patients the integrity of the bladder wall was assessed with MR imaging. In 22 patients the bladder wall was disrupted, and 18 of these patients had deep muscle invasion. In six patients the bladder wall was intact, and none of these patients had evidence of deep muscle invasion at pathologic examination. In this study MR imaging was slightly inferior to CT in the delineation of invasive tumors beyond the bladder wall. However, if one excludes from analysis the two patients with undiagnostic studies, there is no significant difference in accuracy between the two techniques. 相似文献
926.
The authors compared the effectiveness of three anxiety-reducing interventions for patients undergoing magnetic resonance imaging. Each of 50 subjects was randomly assigned to one of the interventions. Intervention 1 involved provision of information about the imager and nature of the examination. Intervention 2 included information and counseling. Intervention 3 included information and a 12-minute relaxation exercise. Anxiety levels were measured by means of a 20-item questionnaire before and after imaging. The latter provided a retrospective report of anxiety experienced during imaging. Patients in intervention group 3 showed significantly less increase in anxiety compared with those in groups 1 and 2. Overall, only patients who participated in intervention 1 showed a significant increase in anxiety during imaging. When anxiety levels experienced before and during the examination were compared, with the focus on each questionnaire item for each group, those in group 1 showed a significant increase in anxiety on eight of 20 items; those in group 2, three items; and those in group 3, none. Psychologic preparation that includes relaxation strategies is more effective than provision of information alone. 相似文献
927.
928.
Q. Timour JF Aupetit J. Loufoua-Moundanga I. Kiouch S. Omar G. Chevrel and G. Faucon 《Fundamental & clinical pharmacology》1992,6(4-5):159-167
Class Ic antiarrhythmic drugs, which are known to slow down conduction in the ventricular muscle, are likely to impair synchrony in activity of the ventricular fibres. Asynchronous activation was first investigated between an ischaemic and a normal area by the simultaneous recording in anaesthetized, open-chest pigs of two left ventricular monophasic action potentials (MAPs) under ventricular pacing at a high rate of 180 beats.min-1. Asynchronous activation was then investigated in the intact myocardium according to the distance separating the recording from the pacing electrode. Furthermore, mechanical effects of left ventricular systole were observed by recording dP/dt(max) and mean arterial blood pressure during the pacing periods. Ischaemia was produced by transient complete occlusion of the left anterior descending coronary artery near its origin; as a result, activation time reached 85 ms in the ischaemic area under flecainide administered iv in a 2.5 mg.kg-1 dose instead of approximately 60 ms in the normal area for fibres equi-distant from the pacing electrode. Similar delays in activation were observed in the intact myocardium, depending on whether the explored region was close to or far from the pacing electrode. In the latter case, the difference in activation time may become markedly greater if the distance or the dose of flecainide are increased. This difference, which possibly exceeds one-third of the MAP duration (practically unchanged by flecainide), may account for the occurrence of fibrillation or the sudden loss of systole mechanical efficacy. 相似文献
929.
930.