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   541篇
  免费   59篇
  国内免费   5篇
耳鼻咽喉   10篇
儿科学   51篇
妇产科学   6篇
基础医学   58篇
口腔科学   28篇
临床医学   55篇
内科学   113篇
皮肤病学   19篇
神经病学   36篇
特种医学   79篇
外科学   59篇
综合类   19篇
预防医学   15篇
眼科学   12篇
药学   31篇
肿瘤学   14篇
  2022年   4篇
  2021年   3篇
  2020年   2篇
  2019年   6篇
  2018年   8篇
  2017年   4篇
  2016年   7篇
  2015年   12篇
  2014年   15篇
  2013年   19篇
  2012年   9篇
  2011年   11篇
  2010年   39篇
  2009年   27篇
  2008年   19篇
  2007年   14篇
  2006年   14篇
  2005年   17篇
  2004年   9篇
  2003年   9篇
  2002年   6篇
  2001年   3篇
  2000年   3篇
  1999年   8篇
  1998年   28篇
  1997年   36篇
  1996年   34篇
  1995年   28篇
  1994年   18篇
  1993年   18篇
  1992年   7篇
  1991年   8篇
  1990年   6篇
  1989年   19篇
  1988年   21篇
  1987年   28篇
  1986年   15篇
  1985年   14篇
  1984年   8篇
  1983年   4篇
  1982年   7篇
  1981年   11篇
  1980年   4篇
  1979年   3篇
  1977年   7篇
  1976年   5篇
  1970年   2篇
  1967年   1篇
  1965年   1篇
  1954年   1篇
排序方式: 共有605条查询结果,搜索用时 78 毫秒
81.
Objective: This study was designed to compare the results of preliminary evaluation, ovarian hyperstimulation, and monitoring of patients at a distant in vitro fertilization satellite center with those treated at the main campus of the program.Study design: Fifty-four patients completing oocyte retrieval cycles at the Eugene satellite Oregon Health Sciences University in vitro fertilization program for the period Jan. 1, 1991, through Dec. 31, 1993, were compared with 222 patients at the main campus for age, peak estradiol level, number of oocytes, retrieved, number of embryos, clinical pregnancy rate, and pregnancy outcome.Results: There were no statistically significant differences between the Eugene in vitro fertilization satellite center and the main campus for any of the factors analyzed with the exception of clinical pregnancy rate. The clinical pregnancy rate per cycle at the Eugene satellite center was 39% while the Portland main campus rate was 23% (p = 0.027), presumably because of a larger number of couples with severe male factor infertility at the central site.Conclusion: A distant in vitro fertilization satellite program was highly successful in the Oregon experience. In addition to greater convenience to the patients, the program was highly comparable to main campus program in measured parameters of ovarian hyperstimulation, oocyte retrieval, number of embryos, and pregnancy rate.  相似文献   
82.
MG  Bruzzone  M  Grisoli  T  De  Simone  C  Regna-Gladin  毛成洁 《中华脑血管病论坛》2005,3(2):188-190
眩晕患者的诊断过程始于对病史以及随后的全身体格检查和神经系统检查的准确评价。这步骤通常能够识别确切的病因,或者至少可鉴别周围性眩晕和中枢性眩晕。神经放射学检查必须作为选择性诊断手段加以考虑,包括CT、MRI、MR血管造影(MRA)以及血管造影术。对于周围性眩晕、良性阵发性位置性眩晕、迷路炎、Meniere病、外淋巴瘘、局部外伤、中毒性迷路炎、急性中耳炎和慢性中耳渗液等疾病的诊断而言,影像学技术的作用是有争议的。CT和MR可用来排除其他病理学原因和证实诊断。分辨率和增加和能够增强迷路内液的特殊MRI序列的应用,使我们能够对迷路的结构和病理学变化进行更详细地分析。T1和T2对比序列检查都是必需的。当怀疑中耳类以及在外伤后眩晕随访时,需要进行高分辨率CT检查。中枢性眩晕的病因很多,包括椎基底循环血管病变、多发性硬化、偏头痛相关性眩晕、小脑和脑干肿瘤以及中枢神经系统感染,其中脑缺血和多发性硬化最为常见。在这些情况下,影像学检查应该是强制性的。CT能够诊断大多数小脑出血以及小脑和脑干的急性缺血,增强的MRI已经证实是检测后颅窝病病变最为敏感的工具。弥散加权MRI能够比常规MRI更早地显示急性缺血性改变。MRA能提供类似血管造影片的颅内血管图像。有证据表明,有时可避免进行侵入性的血管造影术。MRA的分辨率不如传统的血管造影术,还可能受到活动和其他伪影的影响。选择性的后循环血管造影通常对治疗决策有提示作用。  相似文献   
83.
We compared the morphological characteristics of layer III pyramidal neurones in different visual areas of the occipitotemporal cortical 'stream', which processes information related to object recognition in the visual field (including shape, colour and texture). Pyramidal cells were intracellularly injected with Lucifer Yellow in cortical slices cut tangential to the cortical layers, allowing quantitative comparisons of dendritic field morphology, spine density and cell body size between the blobs and interblobs of the primary visual area (V1), the interstripe compartments of the second visual area (V2), the fourth visual area (V4) and cytoarchitectonic area TEO. We found that the tangential dimension of basal dendritic fields of layer III pyramidal neurones increases from caudal to rostral visual areas in the occipitotemporal pathway, such that TEO cells have, on average, dendritic fields spanning an area 5-6 times larger than V1 cells. In addition, the data indicate that V1 cells located within blobs have significantly larger dendritic fields than those of interblob cells. Sholl analysis of dendritic fields demonstrated that pyramidal cells in V4 and TEO are more complex (i.e. exhibit a larger number of branches at comparable distances from the cell body) than cells in V1 or V2. Moreover, this analysis demonstrated that the dendrites of many cells in V1 cluster along specific axes, while this tendency is less marked in extrastriate areas. Most notably, there is a relatively large proportion of neurones with 'morphologically orientation-biased' dendritic fields (i.e. branches tend to cluster along two diametrically opposed directions from the cell body) in the interblobs in V1, as compared with the blobs in V1 and extrastriate areas. Finally, counts of dendritic spines along the length of basal dendrites revealed similar peak spine densities in the blobs and the interblobs of V1 and in the V2 interstripes, but markedly higher spine densities in V4 and TEO. Estimates of the number of dendritic spines on the basal dendritic fields of layer III pyramidal cells indicate that cells in V2 have on average twice as many spines as V1 cells, that V4 cells have 3.8 times as many spines as V1 cells, and that TEO cells have 7.5 times as many spines as V1 cells. These findings suggest the possibility that the complex response properties of neurones in rostral stations in the occipitotemporal pathway may, in part, be attributed to their larger and more complex basal dendritic fields, and to the increase in both number and density of spines on their basal dendrites.   相似文献   
84.
85.
We measured monoamine metabolites and biopterin in the CSF of 37 patients with dementia of the Alzheimer type (DAT), with or without extrapyramidal signs, and in 14 age-matched healthy controls. Compared with concentrations in DAT and controls, the concentrations of homovanillic acid (HVA) and biopterin were significantly decreased in DAT with extrapyramidal signs (EDAT). CSF 3-methoxy-4-hydroxy-phenethyleneglycol and 5-hydroxyindoleacetic acid did not differ significantly among these groups. Age at onset of dementia was positively correlated with CSF HVA (r = 0.49, p less than 0.05). The two dementia groups did not differ significantly in the extent of ventricular dilation as measured by quantitative CT, but EDAT patients had lower Mini-Mental State Examination scores than did DAT patients. When patients were matched for age and dementia severity, CSF HVA and biopterin concentrations remained significantly lower in EDAT than in DAT patients. These results indicate that EDAT patients form a distinct subgroup of DAT with evidence of central monoamine dysfunction.  相似文献   
86.
87.
Lenses were removed from rabbit eyes using an extracapsular technique. Animals were in three groups; no treatment (NT), post-treatment (PT) and pre- and post-treatment (PPT). Treatment consisted of 2% topical indomethacin given three times a day after surgery, except for the PPT group that received 3 drops on the day prior to surgery and drops at 3 hours and 1 hour before surgery. Prostaglandin levels in ocular tissues and fluids were determined at 7, 14 and 21 days post-surgery. Indomethacin decreased prostaglandin formation in most ocular tissues, and was more effective in the PPT group than in the PT group. The data indicate that topical indomethacin suppresses prostaglandin formation from ocular tissues, and that local prostaglandin release from retina and choroid can provide locally high prostaglandin concentrations, regardless of their source, after lensectomy.  相似文献   
88.
89.
90.
A 22 year old male presented with symptoms of diffuse muscle pain and multiple abnormal laboratory findings that were eventually attributed to tropical myositis. Computed tomography scan was more reliable than ultrasound and served as a guide to needle aspiration and pathologic diagnosis.  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