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   9729篇
  免费   502篇
  国内免费   459篇
耳鼻咽喉   141篇
儿科学   57篇
妇产科学   33篇
基础医学   707篇
口腔科学   124篇
临床医学   1510篇
内科学   2027篇
皮肤病学   14篇
神经病学   1076篇
特种医学   869篇
外科学   1110篇
综合类   1753篇
预防医学   354篇
眼科学   68篇
药学   586篇
  4篇
中国医学   178篇
肿瘤学   79篇
  2024年   9篇
  2023年   95篇
  2022年   221篇
  2021年   279篇
  2020年   252篇
  2019年   232篇
  2018年   257篇
  2017年   294篇
  2016年   384篇
  2015年   421篇
  2014年   830篇
  2013年   764篇
  2012年   708篇
  2011年   774篇
  2010年   664篇
  2009年   590篇
  2008年   556篇
  2007年   533篇
  2006年   477篇
  2005年   389篇
  2004年   293篇
  2003年   234篇
  2002年   200篇
  2001年   166篇
  2000年   142篇
  1999年   100篇
  1998年   99篇
  1997年   93篇
  1996年   69篇
  1995年   56篇
  1994年   56篇
  1993年   37篇
  1992年   26篇
  1991年   44篇
  1990年   27篇
  1989年   27篇
  1988年   17篇
  1987年   25篇
  1986年   28篇
  1985年   27篇
  1984年   31篇
  1983年   19篇
  1982年   17篇
  1981年   14篇
  1980年   18篇
  1979年   10篇
  1978年   17篇
  1977年   12篇
  1976年   12篇
  1972年   13篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
报告1例鼻咽癌颈淋巴结转移致颈动脉窦过敏综合征和1例全喉切除加颈淋巴结清扫术术后瘢痕形成出现颈动脉窦过敏综合征。对耳鼻咽喉科相关疾病引起的颈部肿块和瘢痕病变压迫颈动脉窦所致颈动脉窦过敏综合征的致病原因、临床表现及诊断、治疗原则进行了讨论。此类患者在临床上少见,易误诊,应引起重视。  相似文献   
92.
The inhibitory effect of nitric oxide (NO) on carotid chemosensory responses to hypoxia has been attributed in part to an antidromic inhibition of chemoreceptor cells activity. However, NO may also modulate the activity of the primary sensory neurons because NO is produced in the soma of these neurons located in the petrosal ganglion. Since a population of petrosal neurons is selectively activated by acetylcholine (ACh), we studied the effects of NO-donor, sodium nitroprusside (SNP), and the NO-synthase inhibitor, Nomega-nitro-l-arginine methyl ester (l-NAME), on the responses evoked in the carotid sinus nerve (CSN) by ACh applied to the petrosal ganglion in vitro. ACh (1 microgram-1 mg) increased the frequency of action potentials recorded from the CSN in a dose-dependent manner. SNP (10-50 microM) reduced the sensibility and amplitude of the CSN response to ACh, although the maximal response appears less affected. The withdrawal of SNP from the superfusion medium increased the sensibility of the responses to ACh. l-NAME (1-2 mM) slightly increased the sensibility of the ACh-induced responses, effect that persisted after l-NAME withdrawal. These results suggest that NO may play a role as modulator in this autonomic primary sensory ganglion.  相似文献   
93.
目的:研究NOS、O2-·和Ca2+在犬高动力型肺动脉高压形成中的意义,控讨O2-·、[Ca2+]i在L一精氨酸→NO通路上的调节作用。方法:6只高动力型肺动脉高压模型犬,检测肺组织NOS活性,丙二醛(MDA)含量及总钙含量。结果:与正常比较,肺高压时,肺组织NOS活性较正常明显降低(P<0.01),MDA、[Ca2+]i;含量明显升高(P<0.05),肺组织NOS与平均肺动脉压(MPAP)、肺血管阻力(PVR)、[Ca2+]i及MDA呈明显负相关。结论:NO作用减弱在肺高压形成中与限速酶NOS活性降低密切相关,O2·和[Ca2+];共同介导肺高压过程。  相似文献   
94.
Over the last few years, many authors have described the possibility of using transcranial Doppler to demonstrate the passage of microemboli in the cerebral arteries. We report the case of a 44-year-old woman with thrombotic diathesis and thrombocytosis who was admitted twice within a short period of time (one and a half months) to a neurological department because of multiple cerebral infarctions. On the occasion of the second admission, a colour-Doppler examination of the epiaortic vessels, which had previously been negative, showed a carotid lesion due to a mural thrombus and, on the same side as the carotid lesion, transcranial Doppler detected short-duration, high-intensity signals in the middle and anterior cerebral arteries, an expression of the passage of microemboli.As already described by other authors in similar clinical situations, our case confirms that transcranial Doppler can identify the passage of microemboli in the circle of Willis.
Sommario Negli ultimi anni è stata descritta da molti autori la possibilità di dimostrare mediante Doppler transcranico il passaggio di microemboli nelle arterie cerebrali. Riportiamo il caso di una donna di 44 anni con diatesi trombotica e trombocitosi ricoverata per due volte, a breve distanza di tempo (un mese e mezzo), in ambiente neurologico per infarti cerebrali multipli. In occasione del secondo ricovero l'esame Color-Doppler dei vasi epiaortici, che era risultato negativo in precedenza, ha evidenziato una lesione carotidea riferibile a un trombo murale e al Doppler transcranico sono stati rilevati, omolateralmente alla lesione carotidea, segnali di breve durata ed alta intensità nelle arterie cerebrali media e anteriore, espressione di passaggio di microemboli.Come già descritto da alcuni autori in situazioni cliniche simili, il nostro caso conferma la possibilità di individuare, mediante Doppler transcranico, il passaggio di microemboli nel circolo cerebrale.
  相似文献   
95.
Summary A patient with migraine headaches of the cluster variant type is presented in whom vasospasm of the middle cerebral artery, the anterior cerebral artery and the internal carotid artery triggered a pain episode identical in character and severity to the headaches which had led to her investigation. Vasospasm associated with the painful phase of headache in this case conflicts with the more accepted theory that the pain phase of a vascular headache is related to vasodilatation of cerebral or extracerebral vessels. The literature is reviewed.  相似文献   
96.
Summary The effects of carotid occlusion on the release of catecholamines in the nucleus of the solitary tract (NTS) were investigated in anaesthetized cats. Two aspects of the nucleus (rostral or intermediate NTS) were superfused bilaterally through push-pull cannulae with artificial CSF and the release of the endogenous dopamine, noradrenaline and adrenaline was determined in the superfusate radioenzymatically. The superfusion rate was 150 l/min or 800 l/min. In some experiments, superfusion of the intermediate NTS was carried out after denervation of the aortic arch.In the rostral NTS superfused at a rate of 150 l/min, bilateral carotid occlusion led to a rise in blood pressure and decreased the release rate of dopamine. These changes continued after occlusion termination. The release rate of noradrenaline was transiently diminished during occlusion. The release of this amine was also decreased after occlusion termination. The release rate of adrenaline was not influenced during carotid occlusion, but it was found to be diminished after termination of the occlusion. Superfusion of the rostral NTS at a rate of 800 l/min also reduced the release rate of adrenaline after termination of carotid artery occlusion. In the intermediate NTS (superfusion rate 150 l/min) similar effects of the carotid occlusion on the release rates of dopamine and noradrenaline were observed. In this aspect of the NTS, denervation of the aortic arch abolished the decrease in the noradrenaline release during carotic occlusion, while the release rates of dopamine and adrenaline were decreased during and after termination of the carotid occlusion.The results suggest that (a) the rise in blood pressure in the carotid sinus after termination of a carotid occlusion decreases the release rates of noradrenaline and adrenaline in the NTS, (b) the decrease in the release of noradrenaline during carotid occlusion is due to impulses originating from the baroreceptors of the aortic arch.Thus, impulses from carotid sinus and aortic arch modify the release rates of noradrenaline in the NTS so as to counteract blood pressure changes.Supported by the Fonds zur Förderung der wissenschaftlichen Forschung Send offprint requests to A. Philippu at the above address  相似文献   
97.
We report here a 54-year-old man with an aneurysm arising on a cervical anterior radiculomedullary artery. The aneurysm ruptured just after vertebral angiography for a vascular anomaly of the brain, and it appeared to be fusiform, with thrombosis following angiography. Considering the sequential radiological studies and clinical course, it was assumed to be a dissecting aneurysm caused by the angiography. MRI showed severe swelling of the cervical spinal cord and an infarct in the territory of the anterior spinal artery. The mechanism of this rare complication is discussed. Received: 29 March 1999 Accepted: 18 August 1999  相似文献   
98.
目的:探讨针刺治疗动脉再狭窄的作用机理。方法:用空气干燥法诱发大鼠颈总动脉再狭窄模型。以复方丹参注射液作对照。观察针刺对动脉再狭窄模型大鼠颈总动脉去内皮损伤的内膜增生及氧自由基的影响。结果:针刺能抑制动脉去内皮损伤的内膜增生。升高模型大鼠血清中超氧化物歧化酶(SOD)的活性。降低丙二醛(MDA)的含量。结论:针刺具有抗氧自由基的能力。逆转动脉再狭窄的病理进程,对动脉再狭窄具有较好的防治作用。  相似文献   
99.
田维舟  姚声涛 《贵州医药》2003,27(5):393-395
目的 研究低密度脂蛋白胆固醇(LDL-C)/高密度脂蛋白胆固醇(HDL-C)比值以及颈动脉粥样硬化性狭窄与脑梗塞发病的关系,并探讨其预测脑梗塞发生的价值。方法 应用彩色多普勒显保仪对非脑梗塞组患者328例(高血压198例、糖尿病82例、高血压伴糖尿病48例)和脑梗塞组患者260例进行颈动脉检测,观察颈动脉狭窄程度;同时检测两组患者的LDL-C/HDL-C比值水平。结果 脑梗塞组颈动脉重度狭窄发生率明显高于非脑梗塞组(P<0.01);LDL-C/HDL-C比值水平及异常率也明显高于非脑梗塞组(P<0.01),相关分析显示与甘油三酯(TG)、总胆固醇(Tch)、LDL和HDL-C相比,该比值显示了更有意义的与脑梗塞的相关关系(β=0.357,P=0.001),经多元逐步回归分析显示,与TG、Tch、LDL-C和HDL-C相比,该比值显示了更有意义的回归关系,其标准方程式为:γ(脑梗塞)=0.339(糖尿病史) 0.278(LDL-C) 0.187(高血压史)(P<0.贴,复相关系数为0.534)。结论 应用颈动脉超声判定颈动脉重度狭窄和检测LDL-C/HDL-C比值水平及异常率对预测脑梗塞的发生有一定的实用参考价值。  相似文献   
100.
目的 探讨颈总动脉切除术的适应症和术前准备的一般规律。方法 对我院自1986年~2003年17年问的10例颈总动脉切除术病例进行回顾性分析。其中年龄22~59岁,急诊手术4例,选择性颈动脉切除6例。结果 急诊手术中2例出现中枢神经系统并发症,选择性手术组中1例出现中枢神经系统并发症。除1例因脑转移癌死亡外,随访均健在。结论 行不重建血管的颈总动脉及分歧部切除术,高龄患者须严格掌握适应症,须无脑血管疾病史,术前须进行Matas试验,要有侧支循环建立的客观依据;对年轻患者(30岁以下)可适当放宽手术指征。  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