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   2742688篇
  免费   201392篇
  国内免费   11095篇
耳鼻咽喉   37543篇
儿科学   89872篇
妇产科学   74679篇
基础医学   385563篇
口腔科学   76547篇
临床医学   249592篇
内科学   534167篇
皮肤病学   60009篇
神经病学   211333篇
特种医学   105660篇
外国民族医学   910篇
外科学   414033篇
综合类   73904篇
现状与发展   28篇
一般理论   866篇
预防医学   204107篇
眼科学   64395篇
药学   204454篇
  64篇
中国医学   10825篇
肿瘤学   156624篇
  2021年   23383篇
  2019年   23159篇
  2018年   32366篇
  2017年   24738篇
  2016年   26837篇
  2015年   31615篇
  2014年   43536篇
  2013年   61575篇
  2012年   85508篇
  2011年   90658篇
  2010年   54167篇
  2009年   50113篇
  2008年   82875篇
  2007年   88292篇
  2006年   88875篇
  2005年   86015篇
  2004年   81920篇
  2003年   78257篇
  2002年   75678篇
  2001年   135625篇
  2000年   139550篇
  1999年   117568篇
  1998年   32316篇
  1997年   28752篇
  1996年   28905篇
  1995年   27568篇
  1994年   25542篇
  1993年   23350篇
  1992年   90024篇
  1991年   87377篇
  1990年   84430篇
  1989年   80872篇
  1988年   74174篇
  1987年   72668篇
  1986年   68050篇
  1985年   64730篇
  1984年   48083篇
  1983年   40663篇
  1982年   23144篇
  1979年   42576篇
  1978年   29440篇
  1977年   25082篇
  1976年   23324篇
  1975年   25017篇
  1974年   29894篇
  1973年   28537篇
  1972年   26538篇
  1971年   24236篇
  1970年   22718篇
  1969年   20982篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The case reported here demonstrates the importance of considering the possibility of occult malignancy in young patients presenting with extensive or migratory thromboses in atypical locations that appear resistant to standard therapy. Suspicion for malignancy-related thrombosis is heightened by the absence of known precipitating causes and by a negative family history of thrombosis. The search for the responsible underlying neoplasm can be frustrating, but diagnosis and successful treatment of the tumor remain the keys to controlling the abnormal thrombotic state.  相似文献   
992.
993.
We report histological changes in four patients with port wine stains treated with 578 nm yellow light from a high power copper vapour laser. Histology showed that selective damage occurred to the ectatic blood-vessels in the dermis, without haemorrhage and damage to non-vascular structures, and without scarring. The initial damage to the overlying epidermis was not permanent, and the damaged ectatic vessels returned to normal size or were completely necrosed and replaced by collagen.  相似文献   
994.
The advent of recombinant DNA technology has led to the identification in the DNA of normal animal cells of over 30 proto-oncogenes that are homologous to retroviral transforming genes. One of these encodes a protein kinase (pp60c-src) of unknown function, that is preferentially synthesized in brain and neural retina. Here the expression of pp60c-src in the peripheral nervous system was examined in sensory neurons from chick dorsal root ganglia with antisera raised against the transforming protein of Rous sarcoma virus (pp60v-src) expressed in Escherichia coli carrying the cloned v-src gene. This antiserum recognizes pp60c-src specifically in normal chicken cells. Western immunoblotting showed that dorsal root ganglia of stage 30 (day 6.5) chick embryos contained elevated levels of pp60c-src. Immunoperoxidase staining of neuron-enriched cultures prepared from chick dorsal root ganglia showed pp60c-src immunoreactivity in cells with neuronal morphology; flat, fibroblastic cells contained no detectable immunoreactivity. Indirect double immunofluorescence with pp60src antibodies and monoclonal antibodies against the 200-kD subunit of neurofilament protein confirmed that the cells expressing pp60c-src were neurons. Ninety-six percent of the neurofilament-positive cells were immunoreactive with pp60src antibodies, and conversely, all pp60c-src-positive cells were immunoreactive with neurofilament antibodies. pp60c-src immunofluorescence appeared to be distributed over the cell body, processes, and growth cones. These results clearly demonstrate that pp60c-src is a product of neurons and is expressed in sensory neurons in culture.  相似文献   
995.
The present status of total colectomy with ileorectal anastomosis in the surgical treatment of inflammatory bowel disease is examined. Special reference is made to the different indications for the use of the operation in Crohn's disease and in ulcerative colitis. The late results are illustrated by the outcome in the 59 patients in a personal series, and other published results.  相似文献   
996.
Indirect evidence suggests that amphetamine (AMPH) releases dopamine (DA) from an extravesicular, cytoplasmic pool. Disruption of vesicular DA storage by reserpine has been hypothesized to increase the concentration of extravesicular DA available for release by AMPH, which is consistent with the observation that reserpine does not prevent but augments the behavioral response to AMPH. In order to more directly test this hypothesis, the in vivo microdialysis technique was used to concurrently examine the behavioral and striatal dopaminergic response to AMPH (1.25 or 2.5 mg/kg) 24 h following reserpine pretreatment (2.5 mg/kg). Reserpine decreased tissue levels of DA by approximately 90% and reduced baseline dialysate DA concentrations by approximately 80%. Reserpine augmented the behavioural effects of AMPH, particularly increasing the occurrence and intensity of stereotypies. In contrast, reserpine did not alter the amount or duration of AMPH-induced DA release. This observation confirms that DA release by AMPH does not depend on vesicular stores but is inconsistent with the hypothesis that augmentation or behaviour by reserpine results from increased striatal DA release.  相似文献   
997.
Although England/Wales, Italy, and the United States share a common policy of deinstitutionalization, their mental health systems differ considerably. Each country's civil commitment standards define patient eligibility criteria along one of two primary dimensions--need for treatment or degree of dangerousness. These differential selection criteria result in mental health systems serving different subgroups of the total population. The criteria in England/Wales target older women; in the United States, younger men; and in Italy, a group balanced in age and sex. Implications for the current debate on civil commitment policies are considered.  相似文献   
998.
Book Reviews     
Book reviewed in this articles: Essential Paediatric Dermatology . By J, Verbov Skin Disorders in the Elderly . Edited by B. E. Monk , R. A. C. Graham  相似文献   
999.
1000.
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