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   785篇
  免费   41篇
  国内免费   1篇
耳鼻咽喉   10篇
儿科学   56篇
妇产科学   34篇
基础医学   121篇
口腔科学   41篇
临床医学   59篇
内科学   169篇
皮肤病学   7篇
神经病学   48篇
特种医学   37篇
外科学   108篇
综合类   3篇
预防医学   29篇
眼科学   27篇
药学   57篇
中国医学   1篇
肿瘤学   20篇
  2023年   6篇
  2022年   9篇
  2021年   17篇
  2020年   6篇
  2019年   17篇
  2018年   25篇
  2017年   10篇
  2016年   13篇
  2015年   22篇
  2014年   18篇
  2013年   23篇
  2012年   21篇
  2011年   25篇
  2010年   28篇
  2009年   10篇
  2008年   26篇
  2007年   36篇
  2006年   42篇
  2005年   42篇
  2004年   47篇
  2003年   46篇
  2002年   43篇
  2001年   29篇
  2000年   31篇
  1999年   21篇
  1998年   11篇
  1996年   9篇
  1992年   9篇
  1991年   5篇
  1990年   6篇
  1989年   11篇
  1988年   7篇
  1987年   5篇
  1986年   4篇
  1985年   8篇
  1984年   5篇
  1982年   6篇
  1979年   7篇
  1978年   8篇
  1976年   10篇
  1975年   10篇
  1974年   19篇
  1973年   4篇
  1972年   10篇
  1971年   8篇
  1970年   4篇
  1969年   8篇
  1968年   6篇
  1967年   5篇
  1965年   5篇
排序方式: 共有827条查询结果,搜索用时 15 毫秒
1.
2.
3.
P Niederle  A Stárek  V Jezek  I Hes 《Cor et vasa》1988,30(4):272-280
Review of the current state of knowledge about Doppler diagnosis of pulmonary hypertension is presented. The authors compare the findings of numerous studies with their own data and analyse the causes of discrepancies and controversies that have remained to date. Doppler estimation of mean pulmonary artery pressure (PAP) using acceleration time (ACT) measurement in the right ventricular outflow tract or main pulmonary artery has been shown to correlate closely with simultaneously measured values of PAP both at rest and during exercise (r = -0.92 and -0.94, respectively). ACT values show sufficient sensitivity for the detection of pulmonary hypertension (89%), at maximum (100%) specificity. However, Doppler values not obtained simultaneously do not necessarily correlate with PAP in view of rapid physiological variations of PAP. For everyday diagnostic practice in cardiology, prediction based upon mere qualitative estimation of the type of velocity curve seems sufficient. Doppler diagnosis of pulmonary hypertension, little demanding on both technical skills and equipment, is gaining a priority status among the non-invasive methods available.  相似文献   
4.
Patients admitted to hospital after being diagnosed with first-episode schizophrenia were comprehensively assessed prior to acute treatment (on admission), at the end of the acute treatment (at discharge), and at follow-up after 1 year. The psychopathology was evaluated using the Positive and Negative Syndrome Scale (PANSS). 93 patients were reassessed after 1 year. 73/93 (78%) of the patients fulfilled the criteria for remission. No statistically significant differences in the total PANSS or subscales scores were found between remitters and non-remitters before or after the first episode treatment. However, non-remitters had a significantly higher total PANSS score after 1 year than remitters. There was no significant difference in mean psychopathology on admission or at discharge, with the exception of items conceptual disorganization, difficulty in abstract thinking, and lack of judgment and insight between remitters and non-remitters. However, significantly higher mean values were found for all items after 1 year in non-remitters than remitters. On admission the occurrence of positive, negative and general symptoms was balanced; at discharge and after 1 year negative and general symptoms were the most frequently observed. At the 1-year follow-up the impairment of insight and judgment is one of the most frequent symptoms in both remitters (10%) and non-remitters (70%).  相似文献   
5.
The authors present an account on a 12-year-old girl with ectomesodermal dysgenesis of the Rieger type syndrome. The disease was manifested at the age of nine months by transient diffuse corneal opacity, while the intraocular pressure was normal. In addition to typical corneal changes and changes in the angle of the chamber other associated somatic symptoms included megalocornea, high myoptic astigmatism, cleft soft palate, hypoplasia of the upper jaw, partial anodontia, marked thoracic kyphosis, scoliosis, generalized hypermobility and taxicity of the joints and torticollis. Examination revealed an uncommon pathological karyotype 46, XX, t/1,4 (p36, q23). Cytogenetic examination of the parents and siblings of the proband did not disclose any numerical or structural aberrations. The authors reflect on possible causes of the development of the disease and on the differential diagnosis.  相似文献   
6.
Rabbits were sensitized with killed Mycobacterium tuberculosis, M. kansasii, M. avium, M. scrofulaceum, M. fortuitum, and Nocardia asteroides, and their response to homologous and heterologous antigens was assessed in vitro by direct and indirect macrophage migration inhibition tests. The antigens were obtained by disintegration of bacterial mass and by purification of the supernatants by ultracentrifugation. In the direct test, hypersensitivity to homologous antigen was most marked with M. tuberculosis, M. kansasii, and M. avium (migration indices [MI] = 0.42 to 0.50), but was significantly weaker with organisms possessing a lower degree of pathogenic activity (MI for M. fortuitum and N. asteroides = 0.70 and 0.72, respectively). Reactivity to heterologous antigens was also highest in animals sensitized with strongly pathogenic species, approximating normal values in rabbits sensitized with weak pathogens. In the indirect test, the strongest responses were obtained again to homologous antigens (MI = 0.42 to 0.67), and they differed more markedly from reactions to heterologous antigens than in the direct test. The weakest activity of heterologous antigens was again found with M. fortuitum and N. asteroides, where MIs were 0.82 to 0.93.  相似文献   
7.
Antilymphocyte serum was prepared in several species and its effect on the production of migration inhibitory factor (MIF) studied. Antilymphocyte sera in vitro in dilutions as high as 1/3200 inhibited the liberation of MIF by sensitized lymphocytes in the presence of antigen. In contrast antipolymorph and antiglobulin sera were inactive.

Antilymphocyte serum also blocked the formation of MIF when the lymphocytes were preincubated with ALS and then washed before the addition of antigen. The antilymphocyte serum and sera prepared against supernatants containing MIF did not block MIF activity by direct neutralization.

  相似文献   
8.
Cadavers remain a principal teaching tool for anatomists and medical educators teaching gross anatomy. Infectious pathogens in cadavers that present particular risks include Mycobacterium tuberculosis, hepatitis B and C, the AIDS virus HIV, and prions that cause transmissible spongiform encephalopathies such as Creutzfeldt-Jakob disease (CJD) and Gerstmann-Straussler-Scheinker syndrome (GSS). It is often claimed that fixatives are effective in inactivation of these agents. Unfortunately cadavers, even though they are fixed, may still pose infection hazards to those who handle them. Specific safety precautions are necessary to avoid accidental disease transmission from cadavers before and during dissection and to decontaminate the local environment afterward. In this brief review, we describe the infectious pathogens that can be detected in cadavers and suggest safety guidelines for the protection of all who handle cadavers against infectious hazards.  相似文献   
9.
Salivary duct carcinoma (SDC) is highly malignant salivary gland tumour with aggressive clinical behaviour, characterised by its histological resemblance to invasive ductal carcinoma of the breast. Amplification of gene HER-2/neu and overexpression of its gene product have been shown to have both prognostic and treatment implications in breast cancer. The reports concerning the expression of c-erbB2/HER-2/neu in salivary gland tumours are few and controversial. Thus, eleven cases of SDC were evaluated for HER-2/neu status using immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH). To the best of our knowledge, this is the first molecular genetic analysis of SDCs using FISH. HER-2/neu overexpression, identified as strong membrane staining, was observed in all but one case of SDC in majority of neoplastic cells while only four tumours, of nine cases analysed, revealed HER-2/neu gene amplification by means of FISH analysis. SDCs were associated with poor clinical outcome, 6 patients (55%) died of disseminated carcinoma within 4 to 44 months after therapy. There was no difference in outcome of patients with IHC positive-nonamplified and IHC positive-amplified tumours.  相似文献   
10.
Summary Anatomic variations are important in preendoscopic CT evaluation of the paranasal sinuses. In this study, we investigated whether the superior turbinate could become pneumatised like the middle turbinate, pneumatisation of which is well-known. Images of 52 patients who underwent CT examination prior to endoscopic sinus surgery and who had normally aerated posterior ethmoidal cells and an unobscured nasal cavity were retrospectively evaluated. The patients were 12–68 years old (median age, 35 years); 28 were women and 24 were men. Pneumatisation of the superior turbinates was graded in two groups as minimal or marked. Pneumatisation was evident in 25 patients (48%). 13 unilateral (25%), 8 bilateral (15%) pneumatisations were detected in the group graded as minimal, whereas 1 unilateral and 3 bilateral pneumatisations were present in the markedly (8%) pneumatised group of patients. Superior turbinates were seemingly aerated through the posterior ethmoid cells. The superior turbinates can be pneumatised as the middle turbinate is a not frequent anatomic variation that should be taken into account in preendoscopic CT evaluation of the paranasal sinuses.
La pneumatisation du cornet nasal supérieur : une variation anatomique courante ?
Résumé Les variations anatomiques sont importantes à connaitre dans le cadre du bilan tomodensitométrique précédant une chirurgie endoscopique des sinus paranasaux. Dans cette étude, nous avons recherché si le cornet nasal supérieur pouvait être pneumatisé comme l'est le cornet nasal moyen, entité anatomique bien connue. Les images de 52 patients ayant eu une tomodensitométrie avant chirurgie endoscopique et montrant des cellules ethmoïdales postérieures normalement pneumatisées et une cavité nasale nonopaque, ont été évaluées rétrospectivement. Les patients, 28 femmes et 24 hommes, étaient âgés de 12 à 68 ans (moyenne : 35 ans). La pneumatisation du cornet nasal supérieur a été classée en deux groupes; minime et prononçée. Cette pneumatisation était patente chez 25 patients (48 %). Treize pneumatisations unilatérales (25 %) et 8 pneumatisations bilatérales (15 %) furent retrouvées dans le groupe présentant une pneumatisation minime alors que 1 pneumatisation unilatérale et 3 bilatérales (8 %) étaient présentes dans le groupe dont la pneumatisation était plus marquée. Les cornets nasaux supérieurs semblaient être aérés par les cellules ethmoïdales postérieures. Les cornets nasaux supérieurs peuvent être pneumatisés, comme le sont les cornets nasaux moyens, avec une fréquence non-exceptionnelle. Cette variation anatomique mérite d'être prise en considération dans le bilan tomodensitométrique précédant toute chirurgie endoscopique des sinus paranasaux.
  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