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   59677篇
  免费   3591篇
  国内免费   115篇
耳鼻咽喉   799篇
儿科学   2286篇
妇产科学   1376篇
基础医学   7408篇
口腔科学   2619篇
临床医学   4969篇
内科学   13376篇
皮肤病学   1587篇
神经病学   4933篇
特种医学   1757篇
外科学   9045篇
综合类   250篇
一般理论   25篇
预防医学   3954篇
眼科学   1748篇
药学   3558篇
中国医学   257篇
肿瘤学   3436篇
  2024年   42篇
  2023年   483篇
  2022年   576篇
  2021年   1440篇
  2020年   856篇
  2019年   1326篇
  2018年   1976篇
  2017年   1354篇
  2016年   1471篇
  2015年   1536篇
  2014年   1814篇
  2013年   2742篇
  2012年   4396篇
  2011年   4989篇
  2010年   2373篇
  2009年   1746篇
  2008年   4248篇
  2007年   4489篇
  2006年   4350篇
  2005年   4192篇
  2004年   3864篇
  2003年   3651篇
  2002年   3415篇
  2001年   976篇
  2000年   1069篇
  1999年   701篇
  1998年   363篇
  1997年   306篇
  1996年   272篇
  1995年   236篇
  1994年   223篇
  1993年   184篇
  1992年   142篇
  1991年   124篇
  1990年   127篇
  1989年   105篇
  1988年   93篇
  1987年   81篇
  1986年   70篇
  1985年   72篇
  1984年   89篇
  1983年   72篇
  1982年   84篇
  1981年   89篇
  1980年   60篇
  1979年   58篇
  1978年   57篇
  1977年   57篇
  1976年   46篇
  1973年   40篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
BACKGROUND: Lung infection with Burkholderia cepacia complex before lung transplantation in patients with cystic fibrosis is a major risk factor for decreased post-operative survival rates compared with those of patients colonized with the more common opportunistic pathogen Pseudomonas aeruginosa. Because adherence to mucosal surfaces is an important initial step in infection, we investigated the use of non-toxic neutral polysaccharides and a sugar alcohol to prevent adherence of B cepacia complex to allograft airway epithelium. METHODS: We used human airway explants prepared from donor tracheobronchial tissue to test the effect of dextrans and xylitol in inhibiting the binding of Burkholderia cepacia complex. We used immunofluorescence and electron microscopy to determine the distribution of bacteria in the explants. RESULTS: Burkholderia cepacia complex bound to the explants and was found only in the surface mucus layer. Dextran 40 kd applied before adding the bacteria decreased the number of bound organisms by 80% to 99%. Smaller molecular mass dextrans (4 and 20 kd) were ineffective. Xylitol inhibited bacterial binding by 67% to 85%. Both agents seemed to decrease the thickness of the surface mucus, suggesting that they may indirectly inhibit bacterial binding by removing adherent surface mucus. CONCLUSIONS: Treating donor lungs with dextran 40 kd or xylitol before (and possibly after) surgery may inhibit the adherence of Burkholderia cepacia complex to airways and may prevent or decrease subsequent infection of the allografts.  相似文献   
62.
63.
Introduction Hypothalamic hamartomas are congenital malformations. Clinically, they can be asymptomatic, but they cause seizures, mental retardation and precocious puberty in many cases. Case report A 20-day-old boy with hypothalamic hamartoma and bilateral anophthalmia was presented. Except those, no other congenital anomaly was detected. Conclusion This is a rare case of hypothalamic hamartoma with bilateral anophthalmia. The mutations at SOX2 has an important role in the developing brain and eyes.  相似文献   
64.
PURPOSE: Hypothalamic hamartoma (HH) related epilepsy presents with gelastic seizures (GS), other seizure types and cognitive deterioration. Although seizure origin in GS has been well established, non-GS are poorly characterized. Their relationship with the HH and cognitive deterioration remains poorly understood. We analyzed seizure type, spread pattern in non-GS and their relationship with the epileptic syndrome in HH. METHODS: We documented all current seizure types in six adult patients with HH-epilepsy with video-EEG monitoring, characterized clinical-electrographic features of gelastic and non-gelastic seizures and correlated these findings with cognitive profile, as well as MRI and ictal SPECT data. RESULTS: Only four seizure types were seen: GS, complex partial (CPS), tonic seizures (TS) and secondarily generalized tonic-clonic seizures (sGTC). An individual patient presented either CPS or TS, but not both. GS progressed to CPS or TS, but not both. Ictal patterns in GS/TS and in GS/CPS overlapped, suggesting ictal spread from the HH to other cortical regions. Ictal SPECT patterns also showed GS/TS overlap. Patients with GS-CPS presented a more benign profile with preserved cognition and clinical-EEG features of temporal lobe epilepsy. Patients with GS-TS had clinical-EEG features of symptomatic generalized epilepsy, including mental deterioration. CONCLUSIONS: Video-EEG and ictal SPECT findings suggest that all seizures in HH-related epilepsy originate in the HH, with two clinical epilepsy syndromes: one resembling temporal lobe epilepsy and a more catastrophic syndrome, with features of a symptomatic generalized epilepsy. The epilepsy syndrome may be determined by HH size or by seizure spread pattern.  相似文献   
65.
66.
67.
68.
69.
Apical ballooning is a novel clinical entity reported in different contexts of physical and psychological stress, which is more common in middle-aged women. Of unknown etiology, the syndrome is characterized by a sudden and transient dilatation of the left ventricular apex in the absence of obstructive atherosclerotic coronary disease or evidence of myocardial necrosis, with total late recovery of ventricular function. The authors report the case of a 53-year-old woman who was admitted to the emergency room with left arm ischemia and low cardiac output, requiring ventilatory support. Left catheterization showed typical medial and apical myocardial dysfunction, with normal coronary arteries. Transesophageal echocardiography revealed a thrombus attached to the lower face of the aortic arch, which probably explained the thromboembolism of the arm but was unlikely to be the cause of the left ventricular dysfunction since there were no enzymatic or electrocardiographic signs of myocardial necrosis and normal wall motion was fully recovered.  相似文献   
70.
A decrease of heteronymous median nerve-evoked inhibition of corticospinal projections to forearm extensor muscles was reported in a group of 10 dystonic patients by Bertolasi and colleagues in 2003. Here we tested the excitability of corticomotoneuronal connections to both wrist extensor (ECR) and flexor (FCR) muscles after conditioning stimulation of median and also radial nerve at rest in a group of 25 patients with focal hand dystonia compared to 20 healthy subjects. We also investigated the effect of the wrist dystonic posture, either in flexion or in extension, on the afferent modulation of ECR and FCR motor evolved potentials (MEPs). The heteronymous (median-induced) but also homonymous (radial-induced) inhibitions (interstimuli intervals 13-21 ms) of ECR MEP size observed in healthy subjects were decreased in patients. In addition, homonymous (median-induced) facilitation of FCR MEP size was also decreased in patients while heteronymous inhibition (radial-induced) was not. Neither the involvement of the target muscle in the dystonic posture nor the origin of the afferent volley (from a dystonic muscle) influenced the degree of impairment of afferent modulation of the MEP. These findings support the view that a global abnormal somatosensory coupling in focal hand dystonia may contribute to an inadequate motor command to wrist muscles.  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