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   474篇
  免费   27篇
  国内免费   1篇
耳鼻咽喉   4篇
儿科学   6篇
妇产科学   10篇
基础医学   62篇
口腔科学   17篇
临床医学   39篇
内科学   112篇
皮肤病学   10篇
神经病学   32篇
特种医学   5篇
外国民族医学   2篇
外科学   120篇
综合类   4篇
一般理论   1篇
预防医学   32篇
眼科学   9篇
药学   21篇
中国医学   4篇
肿瘤学   12篇
  2024年   2篇
  2023年   3篇
  2022年   14篇
  2021年   18篇
  2020年   19篇
  2019年   10篇
  2018年   24篇
  2017年   23篇
  2016年   20篇
  2015年   15篇
  2014年   31篇
  2013年   40篇
  2012年   38篇
  2011年   40篇
  2010年   29篇
  2009年   17篇
  2008年   39篇
  2007年   30篇
  2006年   15篇
  2005年   8篇
  2004年   8篇
  2003年   4篇
  2002年   9篇
  2001年   6篇
  2000年   5篇
  1999年   2篇
  1997年   1篇
  1994年   1篇
  1992年   2篇
  1991年   1篇
  1989年   1篇
  1987年   4篇
  1986年   4篇
  1985年   2篇
  1984年   2篇
  1982年   1篇
  1978年   2篇
  1977年   1篇
  1973年   2篇
  1972年   3篇
  1971年   2篇
  1970年   2篇
  1967年   1篇
  1965年   1篇
排序方式: 共有502条查询结果,搜索用时 15 毫秒
31.
The true incidence of myocarditis in children is difficult to estimate because many mild cases go undetected. This study describes an unusual cluster of myocarditis cases that occurred in young children living in the greater Baltimore area between May and October 1997. A search of multiple comprehensive databases and interviews with area pediatric cardiologists were conducted to identify unreported cases and determine the background rate of myocarditis in the area. Seven cases of myocarditis were found as well as two with a similar clinical picture and myocardial fibrosis on tissue examination. Six case patients with active myocarditis and one child with fibrosis died. The case children were predominantly black (eight of nine) and male (seven of nine), with no identifiable risk factors. The disease was characterized by a fulminant course with malignant arrhythmias. The greatest number of pediatric myocarditis deaths reported in 1 year prior to 1997 was three. Myocardial tissues were examined using immunohistochemistry, in situ hybridization, and polymerase chain reaction but no etiologic agent was identified. This outbreak is unusual because of both the number of cases and the fulminant course of the disease in this group of children.  相似文献   
32.
A 22-year-old woman presented with acute onset of headache and vomiting. Computed tomography (CT) demonstrated hydrocephalus and a huge midline mass with heterogeneous density involving both lateral ventricles. A small amount of hematoma was detected at the bottom of the left trigone. On magnetic resonance imaging (MRI), the mass appeared grossly isointense on Tl-weighted images and slightly hyperintense on T2-weighted images with a clearly demarcated low intensity area at its center. These CT and MRI findings were suggestive of an acute hemorrhagic event within the tumor. The presence of hemorrhage was confirmed at surgery. Sudden hemorrhages within the tumor were considered to cause the acute onset of symptoms. Although central neurocytoma is not commonly known as a tumor-producing intracranial hemorrhage or to cause abrupt clinical deterioration, we found five similar cases in the literature. After reviewing these cases, we concluded that the information on the possible hemorrhagic complication of central neurocytoma is important for correct diagnosis and thus for proper management of this tumor. Received: 11 March 1999 / Accepted: 15 April 1999  相似文献   
33.
34.
Effects of leptomeningeal tumor on the brain parenchyma was studied by the immunohistochemical method with astroprotein (GFAP) and tubulin in a rat model of meningeal carcinomatosis. Thickening of subpial glial lining (external glial layer) and hypertrophy of subpial astrocytes, detected by the antiserum to GFAP, was the early sign of parenchymal involvement. The glial lining was continuous as far as the tumor cells were confined to the subarachnoid space, however, penetration of tumor cells into subpial brain was associated with disruption of the glial lining. Speculative role of this lining in preventing the tumor cell to infiltrate into brain tissue was discussed. In contrast to the prominent immunohistochemical changes in astrocytes, neuronal tubulin immunoreactivity was not altered even in the late stage of the disease. The present study demonstrated that the leptomeningeal dissemination of tumor cells did cause pathologic change in brain parenchyma as was evidenced by the reactive change of astrocytes. However, the preserved immunoreaction for tubulin suggested that the nerve cell damage was not severe even at the advanced stage of the disease. address for offprints  相似文献   
35.
Several experimental manipulations of the CNS environment successfully elicit regeneration of sensory and bulbospinal motor axons but fail to elicit regeneration of corticospinal axons, suggesting that cell-intrinsic mechanisms limit the regeneration of this critical class of motor neurons. We hypothesized that enhancement of intrinsic neuronal growth mechanisms would enable adult corticospinal motor axon regeneration. Lentiviral vectors were used to overexpress the BDNF receptor trkB in layer V corticospinal motor neurons. After subcortical axotomy, trkB transduction induced corticospinal axon regeneration into subcortical lesion sites expressing BDNF. In the absence of trkB overexpression, no regeneration occurred. Selective deletion of canonical, trkB-mediated neurite outgrowth signaling by mutation of the Shc/FRS-2 activation domain prohibited Erk activation and eliminated regeneration. These findings support the hypothesis that the refractory regenerative state of adult corticospinal axons can be attributed at least in part to neuron-intrinsic mechanisms, and that activation of ERK signaling can elicit corticospinal tract regeneration.  相似文献   
36.
Solitary late recurrence is an unpredictable behavior pattern of renal cell carcinoma. We describe a patient with recurrence at the cranial bone 10 years after surgical management and another with recurrence at the sacral bone 13 years after treatment with radiotherapy and alpha-interferon. Both patients have been followed satisfactorily for 9 months. Unpredictable behavior of renal cell carcinoma makes lifelong followup of patients necessary. If a solitary recurrence is detected operative management definitely should be considered depending on the site of recurrence.  相似文献   
37.
Distributions of two different subclasses of intermediate filaments, vimentin and glial filaments, were studied immunohistochemically in human brain tumors using specific antiserum to each protein subunit, vimentin and astroprotein (GFAP), Surgical specimens (5 meningiomas, 4 ependymomas, 5 benign astrocytomas, 5 anaplastic astrocytomas and 7 glioblastomas) were fixed in 95% ethanol or ethanol-acidic acid (95:5) and embedded in paraffin Avidin biotin peroxidase-complex (ABC) method (Vectastain) was carried out on 6 microns-thick paraffin sections. All meningioma cells were negative for astroprotein (GFAP) and positive for vimentin. Ependymoma cells showed various patterns of immunoreaction for astroprotein (GFAP) but were invariably positive for vimentin. In benign astrocytomas, many cells (or cell body and processes) were positive for astroprotein (GFAP). Immunoreaction for vimentin was, however, less frequent and intense. In anaplastic astrocytomas, population of astroprotein (GFAP)-positive cells decreased and vimentin-positive cells increased. Astroprotein (GFAP)-positive cells were further decreased in glioblastomas and the population of vimentin-positive cells varied among tissues. The present study suggests that the anaplastic change of astrocytoma cells were associated with decreased expression of glial filaments and increased expression of vimentin filaments. It was also suggests that the expression of both intermediate filaments may be suppressed in highly-malignant glial tumor cells.  相似文献   
38.
A prospective high performance liquid chromatography (HPLC) study was performed in eighteen patients with head injury and stroke and four control volunteers to evaluate creatinine and purine metabolites concentration (adenosine, inosine, hypoxanthine, uric acid) in cerebrospinal fluid (CSF). The present HPLC method is rapid, accurate and sensitive in the same isocratic run and no specimen pretreatment of 0.02 ml CSF is necessary. The creatinine level in CSF was increased from 122 to 169 mumol/l in some patients, and was found unrelated to that of serum. The uric acid levels varied between 5.8 and 121 mumol/l and were associated with decrease in Glasgow Coma Scale score and had a critical point of 30 mumol/l. We present initial results in application of HPLC method to measure the creatinine and purine metabolites in CSF. This preliminary report presents that these high levels in CSF of head injury and stroke patients probably reflect tissue damage and an increased tissue catabolism.  相似文献   
39.
40.
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