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   40855篇
  免费   2479篇
  国内免费   2083篇
耳鼻咽喉   41篇
儿科学   748篇
妇产科学   336篇
基础医学   2556篇
口腔科学   107篇
临床医学   6437篇
内科学   4131篇
皮肤病学   57篇
神经病学   8491篇
特种医学   2435篇
外国民族医学   2篇
外科学   2463篇
综合类   8909篇
现状与发展   1篇
预防医学   1301篇
眼科学   93篇
药学   4094篇
  58篇
中国医学   2860篇
肿瘤学   297篇
  2024年   117篇
  2023年   458篇
  2022年   920篇
  2021年   1350篇
  2020年   1356篇
  2019年   1046篇
  2018年   1117篇
  2017年   1327篇
  2016年   1422篇
  2015年   1412篇
  2014年   2634篇
  2013年   2551篇
  2012年   2587篇
  2011年   2563篇
  2010年   2226篇
  2009年   1993篇
  2008年   2029篇
  2007年   2075篇
  2006年   2057篇
  2005年   1792篇
  2004年   1537篇
  2003年   1462篇
  2002年   1220篇
  2001年   1076篇
  2000年   946篇
  1999年   810篇
  1998年   637篇
  1997年   597篇
  1996年   478篇
  1995年   413篇
  1994年   401篇
  1993年   294篇
  1992年   268篇
  1991年   269篇
  1990年   217篇
  1989年   202篇
  1988年   168篇
  1987年   160篇
  1986年   149篇
  1985年   183篇
  1984年   170篇
  1983年   114篇
  1982年   130篇
  1981年   149篇
  1980年   93篇
  1979年   74篇
  1978年   41篇
  1977年   35篇
  1976年   33篇
  1975年   14篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
中风后癫痫的临床研究   总被引:5,自引:0,他引:5  
本文报告36例中风后癫痫发作的临床和CT资料。通过回顾性病历复习和随访发现,中风后癫痫的发生率占同期住院中风患者的5.26%,以蛛网膜下腔出血和脑栓塞发生癫痫比率最高,分别为15%和12.5%。癫痫发作与CT所见病灶分布密切相关,皮质病灶较皮质下病灶更易发生病病。癫痫发作可发生于中风后任何时期,但早期癫痫以出血性中风多见,而迟发性癫痫则更多见于脑梗塞患者。  相似文献   
62.
Background: The practice of laparoscopic cholecystectomy in a community hospital is presented. The morbidity of the procedure is analysed and recommendations for improvement are made. Laparoscopic cholecystectomy was introduced into this 200 bed community hospital in October 1990. All five general surgeons accredited to the hospital agreed to participate in a quality assurance programme to determine the incidence of complications and to make recommendations for improvement. Methods: The records of all 534 patients having laparoscopic cholecystectomy between October 1990 and September 1993 were reviewed, and all complications recorded. Results: Of the 534 cases reviewed in the study 470 were considered uncomplicated and 64 patients experienced a total of 85 postoperative complications. The death of one patient was caused by a pulmonary embolus and another patient experienced a myocardial infarction. Twenty patients has postoperative atelectasis or pneumonia and urinary infection or retention occurred in seven. Complications of laparoscopic cholecystectomy requiring a conversion to open cholecystectomy occurred in eight patients, biliary complications occurred in 18 and 11 patients required re-operation. Conclusions: Three areas of concern were identified. They were the incidence of major biliary injury (0.37% of all cases) and its management, the role of cholangiography. and the incidence and prophylaxis of deep venous thrombosis and pulmonary embolism. Recommendations for improvement in these areas were made.  相似文献   
63.
Summary Different methods have been used in the evaluation and monitoring of the cerebral oxygen supply during neuro-interventional therapies. Attenuation of near-infrared light by the chromophores oxyhemoglobin and deoxyhemoglobin have shown to be useful in the study of the cellular oxygen metabolism and oxygen delivery to the brain. Transcranial cerebral oximetry (TCCO) has the advantage of providing real-time information regarding regional brain oxygen saturation (rSO2) by using wavelengths in the near-infrared range.We present a patient with a carotid cavernous fistula who underwent balloon occulusion and concurrent continuous TCCO monitoring. TCCO was found to be a useful tool providing immediate rSO2 values during the angiographic and interventional procedures. Initial balloon occlusion of a carotid cavernous fistula resulted in partial occlusion of the internal carotid artery lumen causing an immediate decrease in rSO2 which correlated with angiographic findings. Subsequent reocclusion of the fistula produced a slower and smaller degree of decrease in rSO2 with clinical improvement in the patient. Changes in rSO2 were detected before any adverse clinical event was observed. TCCO was reliable, safe, sensitive, and provided a real-time assessment tool for the monitoring of brain oxygen supply in a patient undergoing a neuroendovascular procedure.  相似文献   
64.
Previous work has suggested that there may be a widespread disturbance of motor control mechanisms in patients with cervical dystonia. In the present study, we used transcranial magnetic stimulation to investigate the topography of the corticomotor projection to the abductor pollicis brevis (APB) muscle in 10 subjects with idiopathic torticollis. Threshold-adjusted stimuli were delivered at multiple scalp sites during a low-level voluntary contraction of the APB, and maps were generated of motor evoked potential amplitude versus scalp site. The cortical maps for the APB on the side opposite to the direction of head rotation were displaced laterally or posteriorly in all subjects and reverted to a more normal position after botulinum toxin injection of the cervical muscles in 5 subjects. The findings point to a reversible reorganisation of the corticomotor representation of the hand on the same side as the sternocleidomastoid (SCM) muscle that is involved in producing the dystonia. These results provide further evidence for the involvement of cortical centres and for a more widespread abnormality of motor control mechanisms in focal dystonia. The findings also support the notion that head turning is chiefly mediated by the hemisphere ipsilateral to the direction of the head rotation by means of a corticomotor projection to the contralateral SCM.  相似文献   
65.
Summary This study evaluates local variations of the cerebral vasomotor responses to hypercapnia and haemorrhagic hypotension in a pig model. Four laser Doppler flow probes were used in each pig. There was considerable variation in laser Doppler signals between the four probes in baseline recordings. The increases in flow after CO2 administration in 7 pigs had a mean coefficient of variation of 0.43 ± 0.31, and the flow changes after blood loss in another 7 pigs had a mean coefficient of variation of 0.45 ± 0.34. The range of flow changes within each animal was large; the probe with the highest CO2 response showed on the average a 273% ± 157% larger CO2 response than the probe with the lowest CO2 response. Correspondingly, the probe with the best preserved blood flow after blood loss had on the average a flow value of 93% ± 12% of the baseline value, while the probe that changed most with haemorrhage had a flow value of 44% ± 24% of the baseline value. Single laser Doppler recordings have been used for the monitoring of cerebral blood flow in neurosurgical critical care, but our results suggest that a single laser Doppler flow probe is not an adequate method to monitor vasoreactivity in neurosurgical patients because flow signals from one probe may be unrepresentative for other sites in the brain.  相似文献   
66.
67.
目的 探讨硫酸镁对SD大鼠局灶性脑缺血损伤的保护作用。方法 将 4 0只大鼠随机分成模型对照组、硫酸镁治疗组、亚低温治疗组、硫酸镁联合亚低温治疗组。采用线栓法建立大鼠局灶性脑缺血模型。通过计算大鼠神经功能缺陷评分 ,测量脑梗死体积 ,观察神经元超微结构改变 ,评定硫酸镁联合亚低温治疗作用。结果各治疗组大鼠神经功能评分及脑梗死体积均显著低于对照组 (P <0 0 5 ) ,联合治疗组大鼠明显低于对照组 (P<0 0 1) ;联合治疗组神经元超微结构改变轻微。结论 硫酸镁联合亚低温治疗对大鼠局灶脑缺血有明显保护作用  相似文献   
68.
To define the prevalence of cardioembolic sources found by transesophageal echocardiography (TEE) in different age groups of patients with and without cryptogenic systemic embolism, TEE risk factors for cardiogenic embolism were identified from 341 consecutive patients referred for TEE. One hundred and thirty-five had cryptogenic cerebral or systemic peripheral embolic events (CEE) and 206 other indications for TEE (CTR). Cardioembolic sources were found in 40% of CEE and in 29% of CTR (P < 0.02). Specifically, left atrial (LA) thrombi (P < 0.0001), atrial septal aneurysm with right-to-left shunt (P < 0.002), and atherosclerotic aortic plaques (P < 0.02) were more frequent. The prevalence of potential cardioembolic sources was significantly higher in patients ≥ 70-years old than in younger patients (P < 0.03), specifically LA thrombi (P < 0.004) and atherosclerotic aortic plaques (P < 0.0001). In patients ≥ 70-years old, potential cardioembolic sources were found in 63% and in 40% in CEE and CTR (P = 0.073), respectively. However, LA thrombi were more frequent in CEE (P < 0.003). Thus, potential cardioembolic sources observed by TEE are found more frequently in patients ≥ 70-years old than in younger patients. LA thrombi were more frequent in CEE than in CTR patients ≥ 70-years old. In patients ≥ 70-years old with CEE who are eligible for an anticoagulant regimen, a search for potential cardioembolic sources by TEE should be considered.  相似文献   
69.
The distribution of the specific radioactivity and the incorporation into protein of [3H]-tryptophan and [3H]valine at varying layers from surface to centre were measured in incubated slices of cerebral cortices from infant and adult rats. Specific radioactivity in free amino acids was in both age groups highest in the intact surface layer. Incorporation of tryptophan into protein was even in slices from adult rats but much less than the average in the surface layers in slices from infant rats. Incorporation of valine exhibited similar heterogeneity in both age groups. The results suggest in brain slice preparations a zonal compartmentation of amino acid and protein metabolism which varies for different amino acids.  相似文献   
70.
高血压鼠局部脑梗塞后脑超微结构改变动态观察   总被引:3,自引:0,他引:3  
本文选用肾血管性高血压鼠(RHR)复制大脑中动脉闭塞(MCAO)模型,其后2h至7d分8次取不同区域脑组织进行透射电镜动态观察超微结构的改变。显示局部脑梗塞后发生全脑性改变,其损害程度和出现时间梗塞区最早,以坏死为主,呈完全不可逆性损害;边缘区稍后,主要是微血管塌陷和微血栓形成及部分脑细胞坏死,呈部分可逆性损害,远隔区和镜区最迟,以内皮和星形细胞水肿为主,呈可逆性损害,认为用RHR复制MCAO,更接近于高血压性脑血管损害基础上发生脑梗塞的临床病理改变,全脑超微结构的动态性改变中微血管损害起着重要作用。  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