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   20869篇
  免费   1329篇
  国内免费   671篇
耳鼻咽喉   107篇
儿科学   323篇
妇产科学   209篇
基础医学   1436篇
口腔科学   197篇
临床医学   3079篇
内科学   3675篇
皮肤病学   67篇
神经病学   1438篇
特种医学   1571篇
外国民族医学   3篇
外科学   3622篇
综合类   3193篇
现状与发展   1篇
预防医学   528篇
眼科学   1131篇
药学   1248篇
  11篇
中国医学   474篇
肿瘤学   556篇
  2024年   68篇
  2023年   491篇
  2022年   784篇
  2021年   979篇
  2020年   894篇
  2019年   710篇
  2018年   685篇
  2017年   715篇
  2016年   657篇
  2015年   696篇
  2014年   1372篇
  2013年   1313篇
  2012年   1194篇
  2011年   1293篇
  2010年   1112篇
  2009年   1058篇
  2008年   1076篇
  2007年   1073篇
  2006年   988篇
  2005年   854篇
  2004年   713篇
  2003年   569篇
  2002年   494篇
  2001年   391篇
  2000年   324篇
  1999年   274篇
  1998年   267篇
  1997年   286篇
  1996年   169篇
  1995年   170篇
  1994年   167篇
  1993年   123篇
  1992年   117篇
  1991年   109篇
  1990年   71篇
  1989年   63篇
  1988年   77篇
  1987年   57篇
  1986年   63篇
  1985年   58篇
  1984年   47篇
  1983年   26篇
  1982年   43篇
  1981年   40篇
  1980年   29篇
  1979年   34篇
  1978年   21篇
  1977年   17篇
  1976年   15篇
  1975年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
去胆管及去门静脉肝叶肝细胞功能分化的研究   总被引:1,自引:1,他引:0  
目的 观察胆管结扎及门静脉结扎后肝细胞形态及功能分化现象,探讨去胆管及去门静脉肝叶的保留价值.方法 应用氰基丙烯酸酯对仅保留两个肝叶的大鼠行一叶胆道栓塞并结扎,另一肝叶行门静脉结扎,进行分肝静脉血化验检查、组织病理及超微结构观察.结果 去胆管肝叶形态及糖原染色变化不大,分肝静脉血白蛋白(30.9±1.8)g/L与对照组(31.9±2.0)g/,L比较差异无统计学意义(P>0.05).去门脉肝叶萎缩明显,但血胆红素指标维持正常,与未处理对照组比较[(7.7±3.2)比(8.7±2.3)μmol/L]差异无统计学意义(P>0.05).结论 去胆管肝叶在观察期内无明显萎缩,仍保留有蛋白质合成分泌等功能;去门脉肝叶肝细胞能够承担胆汁代谢功能.  相似文献   
52.
Objective. Employing [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) to assess the correlation between the effect of deep brain stimulation (DBS) on the subthalamic nucleus (STN) and the regional cerebral metabolic rate of glucose (rCMRGlc) in advanced Parkinson's disease patients (N = 8). Materials and Methods. On the basis of patients’ diary records, we performed FDG‐PET during the off‐period of motor activity with on‐ or off‐stimulation by STN‐DBS on separate days and analyzed the correlation between changes in motor symptoms and alterations in the rCMRGlc. Result. When FDG‐PET was performed, the motor score on the unified Parkinson's disease rating scale (UPDRS) was 64% lower with on‐stimulation than with off‐stimulation (p < 0.001, Wilcoxon single‐rank test). STN‐DBS increased the rCMRGlc in the posterior part of the right middle frontal gyrus, which corresponded to the premotor area, and the right anterior lobe of the cerebellum (p < 0.005, paired t‐test). No region exhibited a decrease in rCMRGlc. Among the items of the UPDRS motor score, the changes in resting tremor and rigidity of the left extremities showed a significant correlation with the changes in rCMRGlc observed in the right premotor area (p < 0.02 and p < 0.05, respectively, Spearman's rank correlation). Conclusions. STN‐DBS either activates the premotor area or normalizes the deactivation of the premotor area. These FDG‐PET findings obtained are consistent with the idea that STN‐DBS modifies the activities of neural circuits involved in motor control.  相似文献   
53.
Summary The authors describe an approach through the temporal horn of the lateral ventricle which proved to be useful for clipping of a large dorsal type basilar bifurcation aneurysms. It facilitates the preservation of the perforating arteries behind the aneurysm, because it gives sufficient working space to move the aneurysm dome. Furthermore this approach avoids many of the disadvantages of other approaches, especially the risk of iatrogenic injuries of the Sylvian or Labe's vein.  相似文献   
54.
Neural responses in the dorsal motor nucleus of the vagus (DMV) to topical administrations of sodium and portal infusions of hypertonic saline were investigated electrophysiologically by using multibarrel electrodes in anesthetized rats. Of 102 neurons that showed antidromic response to electrical stimulation of the ventral gastric vagus or the accessory celiac vagus, 51 neurons increased and 13 neurons decreased their discharge rates in response to the electrophoretic administration of sodium. The other 38 neurons did not respond to this stimulation. The portal infusion of hypertonic saline elicited neural responses of some DMV neurons whose axons are involved into either the ventral gastric or the accessory celiac vagus. Further, effects of the topical administration and the portal infusion of hypertonic saline were examined on 33 neurons. Typical response was characterized by an increase in discharge rate responding to both of the portal infusion and the topical administration. In conclusion, the DMV neurons receiving the afferent inputs from hepatoportal osmoreceptors may have an enteroceptor function detecting the change in osmotic pressure of their environment.  相似文献   
55.
为开展脐门静脉造影的介入放射学,弥补肝动脉化疗的不足,探讨肝脏内恶性肿瘤化疗的新途径。本文对8例男性肝脏左叶占位性病变患者作脐静脉穿刺造影测得肝圆韧带内脐静脉自肝门静脉左支囊都至腹壁脐切迹全长为19.4±4.3 cm。讨论了脐门静脉造影的优点及其临床意义。  相似文献   
56.
通过对25例成人尸体的解剖学调查及应用"侧脑室─头静脉分流术"治疗23例梗阻性脑积水的临床疗效观察,旨在确立一种脑积水症手术分流的新途径。23例手术病人显效率92%(21/23)。18例(78%)基本恢复正常。3例(13%)明显好转。2例轻度改善。分析表明:头静脉具备位置浅表恒定、管径适宜、瓣膜可防止血液返流等解剖学特点。是一条可供选择的较为理想的脑积水症分流途径。  相似文献   
57.
We recorded pattern electroretinograms and visual evoked potentials in a group of selected patients with unilateral uncomplicated branch retinal vein occlusion. To document the effects of preexisting risk factors, patients were divided into three groups: diabetes mellitus, hypertension with hyperlipidemia and no systemic disease. The transient and steady-state pattern electroretinogram and visual evoked potential amplitudes were significantly reduced and visual evoked potential peak times were delayed relative to the fellow eyes and agematched normal subjects. There was a second amplitude reduction relative to the other patient groups in both the affected and fellow eyes of the diabetes mellitus group, which was indicative of an additive effect of diabetes mellitus.Abbreviations BRVO branch retinal vein occlusion  相似文献   
58.
A video-assisted right upper lobectomy was successfully performed on a 58-year-old man with an anomalnous segmental pulmonary vein. The tumor was a peripherally located adenocarcinoma. The anomalous vein behind the right main bronchus was identified and safely divided. This case emphasized that to perform this procedure successfully, (1) a careful preoperative evaluation of the anatomy, including the presence of any possible vascular and/or bronchial anomalies, is necessary, and (2) if any anatomical structures cannot be determined intraoperatively, a conversion into an open procedure must immediately be undertaken.  相似文献   
59.
60.
High frequency electrical stimulation by means of electrodes implanted into the brain has become an accepted technique for treatment of Parkinson's disease. The electrical field distribution normally inserted into the sub thalamic nucleus minimise abnormal brain activity. Square wave pulses of 1–3.6 V with duration of 60–90 μs at a frequency range of 130–185 pps are generally used. Every electrode unit consists of four cylindrical electrodes positioned in a row and can be switched on independently. This paper determines the contact impedance of the electrodes for different frequencies and proposes improvement to reduce the contact impedance between the electrodes and the brain. Measurements were performed by placing the electrodes in a tank filled with saline. Different frequencies were applied on two electrodes via a resistor. The current was measured through the resistor and the voltage was registered between one of the electrodes and a third non current carrying electrode. The obtained values were used to calculate the contact impedance. The result shows large contact impedance for the used frequency compared to the impedance of the treated tissue, which means that variation in contact impedance can result in variation in the electrical field applied to the tissue.  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