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   1142篇
  免费   141篇
  国内免费   50篇
耳鼻咽喉   9篇
儿科学   96篇
妇产科学   17篇
基础医学   96篇
口腔科学   44篇
临床医学   104篇
内科学   328篇
皮肤病学   29篇
神经病学   50篇
特种医学   191篇
外科学   65篇
综合类   97篇
预防医学   72篇
眼科学   8篇
药学   65篇
中国医学   3篇
肿瘤学   59篇
  2024年   3篇
  2023年   15篇
  2022年   8篇
  2021年   24篇
  2020年   21篇
  2019年   9篇
  2018年   20篇
  2017年   41篇
  2016年   40篇
  2015年   30篇
  2014年   63篇
  2013年   70篇
  2012年   28篇
  2011年   32篇
  2010年   63篇
  2009年   69篇
  2008年   29篇
  2007年   68篇
  2006年   34篇
  2005年   23篇
  2004年   25篇
  2003年   10篇
  2002年   10篇
  2001年   28篇
  2000年   12篇
  1999年   17篇
  1998年   77篇
  1997年   64篇
  1996年   59篇
  1995年   50篇
  1994年   45篇
  1993年   42篇
  1992年   10篇
  1991年   5篇
  1990年   16篇
  1989年   21篇
  1988年   24篇
  1987年   13篇
  1986年   19篇
  1985年   17篇
  1984年   9篇
  1983年   12篇
  1982年   9篇
  1981年   4篇
  1980年   8篇
  1979年   4篇
  1978年   6篇
  1977年   5篇
  1976年   12篇
  1975年   9篇
排序方式: 共有1333条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
Six hundred forty-five cases of transitional cell carcinoma (TCC) of the bladder, ureter, and/or kidney were reviewed retrospectively to determine the frequency of synchronous and metachronous lesions elsewhere in the urinary tract. Among 597 patients with TCC of the bladder, 23 (3.9%) developed an upper-tract lesion, after an average delay of 61 months. Metachronous upper-tract tumors developed in 13% of 38 patients with primary ureteral TCC and in 11% of 63 with renal TCC, after average delays of 28 and 22 months, respectively. Synchronous TCC was found in 2.3% of patients with bladder TCC, 39% of those with ureteral TCC, and 24% of those with renal TCC. Seventeen percent of the subsequent upper-tract lesions would have been demonstrated by intravenous or retrograde urography performed 1 year after the initial onset of primary bladder cancer, and 61% would have been demonstrated by studies performed within 2 years. Therefore, the authors recommend annual radiologic evaluation of the upper urinary tract for 2 years after initial diagnosis and treatment of an upper-tract or bladder TCC.  相似文献   
995.
A total of 150 colorectal biopsies were performed in 71 patients and correlated with the barium-enema examination (BE). The investigation was divided into two parts. In the first part, involving 19 patients, the depth of each biopsy specimen was determined histologically prior to BE and potential complications related to the biopsy-BE sequence were evaluated. In the second part, involving all 71 patients, the depth of biopsy specimens taken from various colon lesions was determined histologically without regard to the timing of BE. The results confirm previous in vitro findings in pigs and dogs, namely: (a) BE may be performed without delay following a superficial biopsy, but should not be performed until at least 6 days after a deep biopsy; (b) transcolonoscopic biopsies are likely to be superficial, while transproctoscopic biopsies have the potential to be deep; and (c) BE should be delayed at least 6 days following polypectomy or polyp biopsy performed with electrosurgery.  相似文献   
996.
Leptomeningeal metastasis: MR imaging   总被引:3,自引:0,他引:3  
Davis  PC; Friedman  NC; Fry  SM; Malko  JA; Hoffmann  JC  Jr; Braun  IF 《Radiology》1987,163(2):449-454
Seven patients with central nervous system neoplasia and leptomeningeal metastases, proved either at initial diagnosis or on follow-up with contrast material-enhanced computed tomography (CT), were evaluated with magnetic resonance (MR) imaging. In two patients, diffuse sulcal enhancement on CT scans was inapparent on T1- or T2-weighted MR images. Likewise, in four patients diffuse cisternal enhancement on CT scans was not identifiable with MR. Nodular or focal cisternal masses were identified with both CT and MR imaging in three patients; in two, however, MR imaging provided less information. Ependymal and subependymal metastases identified with CT (two patients) were indistinguishable on MR images from periventricular abnormalities of radiation therapy and/or hydrocephalus. These findings suggest that leptomeningeal metastasis may be so subtle or inapparent as to be overlooked with MR imaging alone. Thus, CT and MR imaging should be considered complementary techniques for initial diagnosis and follow-up of tumors with a propensity for leptomeningeal metastasis.  相似文献   
997.
998.
Kaplan  PA; Tu  HK; Williams  SM; Lydiatt  DD 《Radiology》1987,165(1):177-178
Magnetic resonance (MR) images of 28 normal temporomandibular joints were obtained and correlated with respective arthrograms. There was a spectrum in the configuration and thickness of normal articular menisci. The anterior band varied from thin with a flat inferior margin to thick with a bulbous, convex inferior margin. The anatomic configuration of the meniscus as seen with MR correlated directly with normal variations of the anterior recess seen with arthrography. Concavity of the superior aspect of the anterior recess as seen on arthrography was caused by a thick, bulbous anterior band of the meniscus, whereas a flat anterior recess resulted from a thin anterior band without a convex inferior margin. This study emphasizes that the appearance of a concave anterior recess on static arthrograms is not necessarily due to a displaced meniscus.  相似文献   
999.
Brucellar and tuberculous spondylitis: comparative imaging features   总被引:7,自引:0,他引:7  
Radiographs, scintigrams, computed tomographic scans, and magnetic resonance (MR) images of 17 patients with brucellar spondylitis and 15 with tuberculous spondylitis were analyzed to identify distinguishing features. Characteristic findings of brucellar spondylitis included predilection for the lower lumbar spine (68% of lesions), bone destruction limited to the end plates, disk collapse (16 of 19 disks), and granulation tissue or localized soft-tissue edema (17 of 19 sites). MR imaging showed diffuse increased signal in vertebrae and disks on long repetition time (TR)/echo time (TE) images in four patients and focal increased signal with normal disks in one. Epidural extension was best seen on short TR/TE images in four. Tuberculous spondylitis was characterized by predilection for the midthoracic spine (73%), vertebral destruction with gibbus deformity (60%), disk collapse, and paraspinal abscesses (14 of 15). On MR images signal intensity of affected vertebrae was similar to but more severe than findings in patients with brucellar spondylitis. Scintigraphy was the least helpful in differentiating the two infections. Lesions of tuberculous spondylitis affecting the lower lumbar spine were difficult to differentiate from those of brucellar spondylitis.  相似文献   
1000.
Maglinte  DD; Lappas  JC; Chernish  SM; Anger  RT  Jr; Miller  RE 《Radiology》1985,157(2):535-536
Artifacts related to barium flow during double-contrast esophagography may obscure mucosal surface details. Double-contrast esophagograms with flow artifacts of 35 patients were evaluated to determine the effect on radiographic interpretation and to assess the method of examination. Initial radiographs obtained during swallowing of barium were compared with those obtained after a slight delay while patients repeatedly dry swallowed. When severe surface flow artifacts were present, the extent of mucosal disease was underestimated in all cases. Mild surface flow artifacts interfered with the demonstration of the reticular pattern of Barrett esophagus, and luminal flow artifacts caused misinterpretation. The demonstration of strictures was unaffected by flow artifacts. This study suggests that the dry swallowing maneuver and some delay improve depiction of esophageal surface details on double-contrast radiographs and obviate interpretive error from barium flow artifacts.  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