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   5781篇
  免费   282篇
  国内免费   17篇
耳鼻咽喉   57篇
儿科学   108篇
妇产科学   200篇
基础医学   727篇
口腔科学   441篇
临床医学   320篇
内科学   1471篇
皮肤病学   92篇
神经病学   428篇
特种医学   178篇
外科学   863篇
综合类   20篇
一般理论   1篇
预防医学   255篇
眼科学   126篇
药学   268篇
中国医学   18篇
肿瘤学   507篇
  2023年   34篇
  2022年   65篇
  2021年   165篇
  2020年   94篇
  2019年   143篇
  2018年   160篇
  2017年   120篇
  2016年   149篇
  2015年   140篇
  2014年   231篇
  2013年   293篇
  2012年   513篇
  2011年   494篇
  2010年   280篇
  2009年   240篇
  2008年   413篇
  2007年   389篇
  2006年   352篇
  2005年   341篇
  2004年   328篇
  2003年   281篇
  2002年   262篇
  2001年   36篇
  2000年   21篇
  1999年   36篇
  1998年   50篇
  1997年   46篇
  1996年   42篇
  1995年   34篇
  1994年   38篇
  1993年   24篇
  1992年   17篇
  1991年   20篇
  1990年   16篇
  1989年   17篇
  1988年   16篇
  1987年   12篇
  1986年   19篇
  1985年   8篇
  1984年   9篇
  1983年   11篇
  1982年   21篇
  1981年   12篇
  1980年   12篇
  1979年   9篇
  1977年   5篇
  1976年   6篇
  1974年   6篇
  1973年   7篇
  1972年   6篇
排序方式: 共有6080条查询结果,搜索用时 15 毫秒
1.
2.
Cementoblastomas are benign lesions of the odontogenic ectomesenchyme that rarely occur related to the primary dentition, especially on the left side of the mandible. This study describes a case of a true cementoblastoma related to the left second primary mandibular molar in a 7-year-old child (the largest one seen in the left side of the mandible). Additionally, the radiographic and histologic findings of the lesion are described in details.  相似文献   
3.

Background  

Heart chambers rupture in blunt trauma is uncommon and is associated with a high mortality. The determinant factors, and the incidence of isolated heart chambers rupture remains undetermined. Isolated rupture of the right atrium appendage (RAA) is very rare, with 8 cases reported in the reviewed literature. The thin wall of the RAA has been presumed to render this chamber more prone to rupture in blunt trauma.  相似文献   
4.
Forty-four evaluable patients with intracranial meningiomas were assessed for the expression of the cell-cycle regulator cyclin D1 and of proteins involved in proliferation and apoptosis such as PCNA, MIB-1, p53 and bcl-2. Analyses were carried out by western blot and immunohistochemistry after immediate processing of fresh tumor specimens. By western blot, expression of cyclin D1 significantly correlated with p53 (p=0.02) and with proliferative activity, as assessed by PCNA expression (p=0.0009). By immunohistochemistry, a significant relationship between cyclin D1 and the proliferation marker MIB-1 was confirmed (p=0.05), whereas significance with bcl-2 expression was not found (p=0.01). Moreover, although the association with tumor grade appeared of borderline statistical significance (p=0.07), all the grade II/III meningiomas showed increased expression of cyclin D1 and high proliferative activity. In conclusion, data from this preliminary study seem to suggest a potential value of the combined expression of cyclin D1 and proliferation indicators in defining subgroups of meningiomas with a more aggressive biological behavior.  相似文献   
5.
6.
7.
Purpose  To present a case of brainstem anaesthesia as a complication of peribulbar anaesthesia. Clinical features  A 75-yr-old woman received peribulbar anaesthesia for cataract surgery. A few seconds after the block was performed, she had a respiratory arrest, became unconscious, and developed hypertension and tachycardia followed by hypotension and bradycardia. Ventilatory and haemodynamic support were performed before the patient regained adequate spontaneous breathing and normal heart rate and blood pressure. Conclusion  Peribulbar anaesthesia generally cames a low risk of serious complications. However, respiratory arrest and brainstem anaesthesia may occur as complications of peribulbar blocks.
Résumé Objectif  Présenter un cas d’anesthésie du tronc cérébral compliquant une anesthésie péribulbaire. éléments cliniques  Un bloc péribulbaire était réalisé chez une femine de 75 ans pour l’extraction d’une cataracte. Quelques secondes après l’injection, la patiente cessait de respirer et perdait conscience. Elle devenait hypertendue et tachycarde puts hypotendue et bradycarde. La ventilation et la circulation devaient être supportées jusqu’au retour spontané à la normale. Conclusion  En général, l’anesthésie péribulbare comporte un faible risque de complications sérieuses. Un arrêt respiratoire par anesthésie du tronc cérébral est toujours possible.
  相似文献   
8.
9.
Support vector machines (SVMs) are a powerful technique developed in the last decade to effectively tackle classification and regression problems. In this paper we describe how support vector machines and artificial neural networks can be integrated in order to classify objects correctly. This technique has been successfully applied to the problem of determining the quality of tiles. Using an optical reader system, some features are automatically extracted, then a subset of the features is determined and the tiles are classified based on this subset.  相似文献   
10.
Amphetamine (AMPH) is an indirect sympathomimetic compound classified as a substrate-type releaser that distinguishes it from other stimulants that act as uptake 1 blockers, such as cocaine (COC). In mammals, AMPH elicits central stimulation, hypermotility, anorexia, analgesia and analeptic activity, mainly through the increase of extracellular brain dopamine (DA). The inversion of vesicular transporters and/or intravesicular alkalinization is assumed to have a role in AMPH-induced exocytosis. However, the action mechanism of this compound has not yet been completely clarified. Recent evidence on the action of AMPHs indicates potassium channel-blocking properties in peripheral tissues. We investigated the possible involvement of a Shaker-like Kv1.1 channel subtype in the central effects of AMPH, using an antisense oligodeoxyribonucleotide (aODN) that specifically and reversibly inhibits the expression of these channels in the brain. The effect of aODN pretreatments was studied by evaluating the modification of behavioral effects induced in mice through the intracerebroventricular administration of AMPH, COC, or other compounds. The aODN in mice almost completely blocked the stimulatory effects of AMPH and other releasers but was ineffective in reducing the central activity of COC. In aODN-pretreated rats a strong reduction of the AMPH, but not of the COC-stimulated DA efflux from nucleus accumbens was observed. Our results suggest that the stimulant effects of AMPH and chemically related compounds, but not COC, require the presence of functionally active Kv1.1 channels in the brain.  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