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   229篇
  免费   13篇
  国内免费   1篇
耳鼻咽喉   1篇
儿科学   22篇
妇产科学   1篇
基础医学   17篇
口腔科学   4篇
临床医学   20篇
内科学   50篇
皮肤病学   3篇
神经病学   26篇
特种医学   27篇
外科学   19篇
综合类   6篇
预防医学   13篇
眼科学   5篇
药学   14篇
中国医学   1篇
肿瘤学   14篇
  2023年   4篇
  2022年   2篇
  2021年   3篇
  2020年   6篇
  2019年   4篇
  2018年   7篇
  2017年   5篇
  2016年   4篇
  2015年   7篇
  2014年   3篇
  2013年   11篇
  2012年   5篇
  2011年   10篇
  2010年   8篇
  2009年   9篇
  2008年   8篇
  2007年   8篇
  2006年   6篇
  2005年   7篇
  2004年   10篇
  2003年   5篇
  2002年   7篇
  2001年   8篇
  2000年   4篇
  1999年   4篇
  1998年   16篇
  1997年   12篇
  1996年   12篇
  1995年   10篇
  1994年   4篇
  1993年   3篇
  1992年   2篇
  1990年   2篇
  1989年   3篇
  1988年   2篇
  1987年   3篇
  1986年   2篇
  1985年   6篇
  1982年   1篇
  1981年   3篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1977年   2篇
  1976年   2篇
排序方式: 共有243条查询结果,搜索用时 9 毫秒
61.
62.
Three previously healthy children, two girls aged 2 and almost 5 years and a boy aged 20 months, developed a progressively stumbling gait within days. In two this occurred after a period of weeks during which they complained of, or seemed to have back pain. In all three cases acute spinal cord compression by a malignant tumour was diagnosed. Histological examination revealed Ewing sarcoma, granulocytic sarcoma and T-cell lymphoma. Surgical decompression led to complete neurological recovery. Although rare, acute spinal cord compression during childhood is a medical emergency because of the risk of neurological morbidity. Back pain, weakness and a stumbling gait usually are the first symptoms. Sensory symptoms and sphincter dysfunction may develop later. Early recognition is essential, as prognosis depends on neurological findings and duration of symptoms when treatment is started.  相似文献   
63.
An understanding of the natural history of childhood chronic idiopathic thrombocytopenia purpura (ITP) could contribute to a rational therapeutic approach to its treatment, which remains controversial. In our retrospective study of 92 children with ITP, 22 had a chronic course and were followed for 3–14 years (median 8.6 years). Treatment, when indicated, was individualized: 4 patients (18.2%) did not receive any treatment, 14 (63.6%) received steroids only, while 4 (18.2%) were treated with steroids and one of the following: high-dose gamma globulin (4 patients), splenectomy (2 patients) or immunosuppressive therapy (2 patients). During follow-up, 14 patients (63.6%) achieved complete remission, 5 (22.7%) partial remission and only 3 (13.5%) remained severely thrombocytopenic, with minimal bleeding tendency. Eleven patients (50%) responded to the initial prednisone course (1–5mg/kg/day), but showed a marked decrease in platelet count when steroids were tapered off. In view of the high rates of complete and partial remission and the mild course of the few non-responding patients, it is suggested that with adequate supportive therapy, follow-up problems and fatalities can be kept to a minimum. We believe that aggressive therapy, such as splenectomy, should be reserved for the rare symptomatic and severely thrombocytopenic patient.  相似文献   
64.
65.
A new fast method of measuring kinetic reaction rates for two-site chemical exchange is described. The method employs saturation transfer magnetic resonance spectroscopy (MRS) and acquisition of only four spectra under partially saturated, high signal-to-noise ratio (SNR) conditions. In two acquisitions one of the exchanging species is saturated; the other two employ a control saturation. Each pair of acquisitions is applied with two different flip angles, and the equilibrium magnetization, relaxation times, and reaction rates are calculated therefrom. This four-angle saturation transfer (FAST) method is validated theoretically using the Bloch equations modified for two-state chemical exchange. Potential errors in the rate measurements due to the effects of exchange are evaluated for creatine kinase (CK) metabolism modeled for skeletal and heart muscle, and are found to be < 5% for forward CK flux rates of 0.05 < or = k(f) < or = 1.0 s(-1), and up to a 90% depletion of phosphocreatine (PCr). The effect of too much or too little saturating irradiation on FAST appears to be comparable to that of the conventional saturation transfer method, although the relative performance deteriorates when spillover irradiation cuts the PCr signal by 50% or more. "FASTer" and " FASTest" protocols are introduced for dynamic CK studies wherein [PCr] and/or k(f) changes. These protocols permit the omission of one or two of the four acquisitions in repeat experiments, and the missing information is recreated from initial data via a new iterative algorithm. The FAST method is validated empirically in phosphorus ((31)P) MRS studies of human calf muscle at 1.5 T. FAST measurements of 10 normal volunteers yielded the same CK reaction rates measured by the conventional method (0.29 +/- 0.06 s(-1)) in the same subjects, but an average of seven times faster. Application of the FASTer algorithm to these data correctly restored missing information within seven iterations. Finally, the FAST method was combined with 1D spatially localized (31)P MRS in a study of six volunteers, yielding the same k(f) values independent of depth, in total acquisition times of 17-39 min. These timesaving FAST methods are enabling because they permit localized measurements of metabolic flux, which were previously impractical due to intolerably long scan times.  相似文献   
66.
67.
Bloodspot cortisol, where finger pricked blood is applied to blotting paper, is suitable for repeated measurements in the home environment. The use of bloodspot cortisol measurements in children with asthma and the effect of inhaled corticosteroids on daytime cortisol concentrations were assessed. Twenty children with mild asthma were randomised to receive double blind either placebo or beclomethasone dipropionate 200 micrograms twice daily. Blood was taken by finger prick at home on waking, and treatment administered. Blood was then taken one hour after treatment, at lunchtime, and in the evening. The area under the curve (AUC) for the four time points was calculated as a composite index of daytime cortisol. Mean (SEM) bloodspot cortisols fell progressively over the day from 199.2 (15.6) nmol/l to 58.4 (8.9) nmol/l. Cortisol in the group treated with beclomethasone dipropionate was lower at all time points, but was significant only after treatment (mean (SEM) 120.9 (14.3) v 177.5 (21.0) nmol/l) and at lunchtime (mean (SEM) 82.7 (12.4) v 128.9 (12.6) nmol/l). AUC for the beclomethasone dipropionate treated group was also significantly decreased (mean (SEM) 317 (31.4) v 446 (29.7)). Beclomethasone dipropionate at a dose of 400 micrograms/day significantly suppresses the daytime cortisol profile.  相似文献   
68.

Objectives  

Evaluating the original, and the revised version of the Dutch Childhood Health Assessment Questionnaire (CHAQ). To explore the effect of different score calculation methods and eight more challenging items as proposed by Lam et al. (2004) on the score distribution in a population of patients with Juvenile Idiopathic Arthritis (JIA).  相似文献   
69.
The Otago photoscreener is a 35 mm single lens reflex camera in which the flash light comes from a narrow ring around the outer margin of its lens. The margin is also the limiting aperture of the optic system and in the centre of the lens is a flickering fixation light. In a colour photograph taken at a distance of 66 cm from the face of the subject who is accurately focusing on and fixing the camera fixation light with both eyes, the fundus reflex in each pupil is very dark red and the corneal light reflexes are symmetrical. If either or both eyes are not appropriately focused or fixing, the fundus reflex is brighter and yellow or white. This article describes a prospective trial of the performance of the Otago photoscreener in a series of 1000 infants with actual or suspected amblyopia, refractive error or strabismus. In this study photoscreening showed a sensitivity of 94% and a specificity of 79%. Photoscreening also identified some cases of esotropia and of refractive error which were missed on clinical examination. In this series photoscreening passed as normal three children with mild to moderately severe amblyopia. This represents les than 1 % of the clinically abnormal children.  相似文献   
70.
143B.206 rho degrees cells were repopulated with mitochondria from a MELAS patient harbouring a mixture of 3243G:C and 3243A:T mitochondrial DNA. A number of biochemical assays were performed on selected cybrids with various proportions of the two types of mitochondrial DNA. These assays revealed a marked decrease in oxygen consumption with pyruvate, a complex I substrate, in cybrids containing 60% to 90% 3243G:C mitochondrial DNA. Moreover, these cybrids showed decreased synthesis of a number of polypeptides in a mitochondrial in vitro translation assay. A cybrid line with a very high level of 3243G:C mitochondrial DNA (95%) had additional deficiencies in complexes III and IV and there was a marked generalised decrease in mitochondrial translation in this cybrid. The observation of complex I deficiency is consistent with previously reported enzymatic measurements of muscle homogenates from MELAS patients with the 3243G:C mutation.   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