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   20503篇
  免费   1229篇
  国内免费   37篇
耳鼻咽喉   385篇
儿科学   608篇
妇产科学   344篇
基础医学   2931篇
口腔科学   469篇
临床医学   1819篇
内科学   3900篇
皮肤病学   374篇
神经病学   2067篇
特种医学   958篇
外国民族医学   12篇
外科学   3012篇
综合类   183篇
一般理论   6篇
预防医学   1510篇
眼科学   734篇
药学   1355篇
中国医学   41篇
肿瘤学   1061篇
  2021年   300篇
  2020年   182篇
  2019年   254篇
  2018年   302篇
  2017年   234篇
  2016年   265篇
  2015年   327篇
  2014年   412篇
  2013年   612篇
  2012年   865篇
  2011年   856篇
  2010年   512篇
  2009年   485篇
  2008年   800篇
  2007年   870篇
  2006年   817篇
  2005年   811篇
  2004年   774篇
  2003年   690篇
  2002年   740篇
  2001年   701篇
  2000年   716篇
  1999年   625篇
  1998年   252篇
  1997年   238篇
  1996年   203篇
  1995年   172篇
  1994年   153篇
  1993年   131篇
  1992年   415篇
  1991年   430篇
  1990年   412篇
  1989年   371篇
  1988年   388篇
  1987年   342篇
  1986年   343篇
  1985年   304篇
  1984年   241篇
  1983年   180篇
  1982年   135篇
  1979年   222篇
  1978年   166篇
  1977年   164篇
  1976年   149篇
  1975年   153篇
  1974年   176篇
  1973年   145篇
  1972年   146篇
  1970年   136篇
  1968年   136篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
61.
A patient known with acute intermittent porphyria who developed primary liver-cell carcinoma is described. No other risk factors were found. A possible association of acute intermittent porphyria with the development of primary liver-cell carcinoma has been suggested in recent, mainly Scandinavian literature. So far this association has never been described in The Netherlands.  相似文献   
62.
During the 30-month period from March 1, 1988, through August 31, 1990, image-guided aspirations of 183 solitary occult breast masses, which were considered possible cysts, were performed. Indications for aspiration included (1) mass on mammography, either invisible on ultrasonography or with features atypical of a cyst, in 111 patients; (2) enlarging solitary mass on mammography with ultrasonic features suggesting a cyst in 45 patients; and (3) mammographic mass with features typical of a cyst in 27 patients, with confirmation requested by the referring physician. Of the group, 151 (83%) lesions were fluid-filled and 32 (17%) were solid. All aspirates had normal cytologic features. Of the 32 aspirates found to be solid, 19 were subsequently removed after wire localization and 13 were unchanged on mammography for a minimum of 6 months after aspiration. This is a simple and safe procedure, confirming the innocuous nature of an occult solitary breast cyst, and obviates the need for surgical biopsy.  相似文献   
63.
Cochlear implantation is a treatment for profound bilateral cochlear hearing loss. Two broad varieties of cochlear implants are used: single or multichannel device (22- channel) inserted either into the cochlea (tympanic ramp) or on the promontory on round window Imaging modalities have to predict cochlear patency prior surgery, an essential factor for choosing between intra or extra cochlear implant. Since March 1991, we have investigated 23 implant candidates to evaluate cochlear patency prior surgery, 6 patients underwent surgery: 4 had a multichannel and 2 had a monochannel electrode. Both CT and MRI play a role in pre operative study. CT easily predicts cochlear ossification and labyrinthine malformations MRI (3 D applications) with T 2 Weighted images, one millimeter thick, more clearly depicts labyrinthine liquid and can predict cochlear fibrosis before ossification.  相似文献   
64.
65.
66.
In this retrospective study of 24 patients who were treated at our clinic during the last 22 years after having attempted suicide, we evaluated aspects concerning abdominal-and transplantation surgery. There was a predominance of “hard” (70%) versus “soft” (30%) methods for suicide attempt. Intra-abdominal injuries resulting from attempted suicide by stabbing or shooting should lead to laparotomy— the prognosis is then good. Surgical treatment after intoxication, especially caustic ingestion, depends on endoscopic and clinical findings. The highly increased rates of suicide significantly by kidney transplantation. The risk of suicide after transplantation is further diminished with improved immunosuppressive treatment. Only in a few cases there is an indication for liver transplantation— in some cases of fulminant hepatic failure caused by self-administered paracetomol overdose. Auxiliary liver transplantation may then be considered.  相似文献   
67.
68.
Mycobacterium fortuitum NRRL B-8119 transformes sterols into 9 alpha-hydroxy-androsta-4-ene-3,17-dione (9OH-AD) at high efficieny. Cells strongly aggregate to the surface of the sterol particles forming stable agglomerates (“substrate immobilized cells”). Substrate uptake and product formation were studied as function of the size of the sterol particles. Using particle sizes comparable with the size of the mycobacterial cells (> 5μm) highest rates were found for both the substrate uptake and the product formation. After mechanical reinforcement of the contact between mycobacterial cells and the sterol substrate by co-grinding of the components, a significantly increased product formation was observed. Associated cells and cell-sterol agglomerates were investigated by freeze-fracture electron microscopy. The micrographs obtained demonstrate that cells of M. fortuitum are growing into the sterol microcrystallite. The uptake of the sterol substrate is assumed to take place via direct contact between cells and the substrate particles. To understand the transport mechanism a model is proposed that includes a flexible multicomponent mesophase (FMCM) which is placed between cells and particles and which mediates the sterol uptake. The putative FMCM is assumed to be composed of mycobacterial glycolipids, extracellular biolipids, synthetical detergents, sterol and water.  相似文献   
69.
70.

Background  

The behaviour of children with Attention-Deficit/Hyperactivity Disorder is characterized by low predictability of responding. Low behavioural predictability is one way of operationalizing intra-individual ADHD-related variability. ADHD-related variability may be caused by inefficient behavioural selection mechanisms linked to reinforcement and extinction, as suggested by the recently published dynamic developmental theory (DDT) of ADHD. DDT argues that ADHD is a basic neurobehavioural disorder, caused by dysfunctioning dopamine systems. For establishing ADHD as a neurobehavioural disorder, findings from studies conducted in Western countries should be replicated in other cultural populations. The present study replicated the study conducted in Norway, with children from the Limpopo province in the Republic of South Africa.  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