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   583篇
  免费   27篇
  国内免费   2篇
耳鼻咽喉   3篇
儿科学   58篇
妇产科学   4篇
基础医学   69篇
口腔科学   12篇
临床医学   73篇
内科学   136篇
皮肤病学   21篇
神经病学   5篇
特种医学   141篇
外科学   22篇
综合类   16篇
预防医学   8篇
眼科学   7篇
药学   14篇
肿瘤学   23篇
  2022年   2篇
  2021年   5篇
  2020年   1篇
  2019年   1篇
  2018年   7篇
  2017年   1篇
  2016年   4篇
  2015年   11篇
  2014年   9篇
  2013年   15篇
  2012年   11篇
  2011年   14篇
  2010年   24篇
  2009年   20篇
  2008年   14篇
  2007年   5篇
  2006年   15篇
  2005年   10篇
  2004年   4篇
  2003年   12篇
  2002年   7篇
  2001年   5篇
  2000年   4篇
  1999年   3篇
  1998年   35篇
  1997年   46篇
  1996年   47篇
  1995年   36篇
  1994年   20篇
  1993年   23篇
  1992年   9篇
  1991年   13篇
  1990年   6篇
  1989年   17篇
  1988年   27篇
  1987年   21篇
  1986年   23篇
  1985年   13篇
  1984年   5篇
  1983年   5篇
  1982年   5篇
  1981年   14篇
  1980年   6篇
  1979年   5篇
  1978年   8篇
  1977年   9篇
  1976年   5篇
  1975年   9篇
  1974年   1篇
排序方式: 共有612条查询结果,搜索用时 15 毫秒
101.
102.
103.
Background/Aims To retrospectively evaluate the clinicopathological features, treatment modalities and factors affecting prognosis in patients with both conjunctival intraepithelial and invasive squamous neoplasms. Method Review and analysis of clinical and pathological records of all cases histologically diagnosed in the Department of Pathology, University College Hospital, Ibadan, Nigeria between January 1990 and December 2004. Results There were a total of 46 cases in 45 patients (eight intraepithelial carcinomas, 37 invasive squamous cell carcinomas (SCC) and a single case of mucoepidermoid carcinoma in a 71-year-old man). The intraepithelial neoplasms occurred in patients aged between 20 and 90 years. Seven of these patients had actinic changes on histology. For invasive SCC, patients’ ages ranged from 18 to 84 years with a mean age of 53 years. Male to female ratio was 1:1. The majority presented with an orbital mass and loss of vision. Twenty-two (60%) of the patients with invasive SCC had enucleation or exenteration as the primary modality of treatment with or without radiotherapy or chemotherapy. Altogether for intraepithelial and invasive squamous neoplasms, the duration of presenting complaints ranged from 1 month to 5 years with an average of 2 years. Human immunodeficiency virus (HIV) infection and smoking were not significantly associated with these cases but a significant number had outdoor occupation. Low socioeconomic status and inability to afford treatment was common among our patients. Conclusion Patients with invasive SCC in Nigeria present late and have significant delay before having any form of treatment. This contributes to the poor outcome. Human papilloma virus (HPV) and actinic aetiology are possible strong causative agents in Nigerians.  相似文献   
104.
Detecting pre-ovulatory luteinizing hormone surges in urine   总被引:2,自引:1,他引:2  
The study objectives were to determine (i) if pre-ovulatory luteinizing hormone (LH) surges, undetected in urine by two immunoradiometric assays (IRMA), were detectable by an ultrasensitive immunofluorometric assay (IFMA) and (ii) the influence of creatinine adjustment on the detection and timing of the urinary LH surges. Daily urine specimens were contributed by healthy 25-36 year old volunteers during 14 ovulatory menstrual cycles for an epidemiological study conducted in 1983-1985. Specimens were selected as having been previously assayed by two IRMA without consistently detecting LH surges. These urine specimens were remeasured using an IFMA and adjusted for creatinine concentration. IFMA measurements revealed unambiguous LH surges in all cycles. Adjusting IRMA urinary LH values for creatinine concentrations revealed previously undetected LH surges in four of eight cycles. Creatinine adjustment also altered the timing of IRMA and IFMA LH surges by 1-5 days. These results demonstrate an IFMA that detects pre- ovulatory LH surges in unpreserved, frozen urine from cycles where such surges were previously undetectable. Further, creatinine adjustment can markedly affect detection and timing of the onset and peak of the urinary LH surge. While our analysis suggests that this adjustment improves the validity of the LH measure, this requires further investigation.   相似文献   
105.
Objective  To study associations between maternal dietary and supplement intake of antioxidants vitamin E, retinol and congenital heart defects (CHDs).
Design  Case–control study.
Setting  Erasmus MC, University Medical Center Rotterdam, the Netherlands.
Population  Participants were 276 case mothers of a child with CHD and 324 control mothers with their children.
Methods  Food frequency questionnaires covering the intake of the previous 4 weeks were filled out at 16 months after the index pregnancy. Data were compared between cases and controls using the Mann–Whitney U test. Risk estimates for the association between CHD and dietary intake of vitamin E and retinol were estimated in a multivariable logistic regression model.
Main outcome measures  Medians (5–95th percentile) and odds ratios with 95% CI.
Results  Dietary vitamin E intake was higher in case mothers than in controls, 13.3 (8.1–20.4) and 12.6 (8.5–19.8) mg/day ( P = 0.05). CHD risk increased with rising dietary vitamin E intakes ( P -trend = 0.01). Periconception use of vitamin E supplements in addition to a high dietary vitamin E intake above 14.9 mg/day up to nine-fold increased CHD risk. Retinol intakes were not significantly different between the groups and not associated with CHD risk.
Conclusions  High maternal vitamin E by diet and supplements is associated with an increased risk of CHD offspring.  相似文献   
106.
本文用兔抗心钠素Ⅲ特异血清,用ABC法观察了大鼠脑内心钠素的分布。结果表明心钠素在脑内广泛存在。密集的心钠素免疫反应阳性神经元,主要见于下丘脑视前区、室周核及下丘脑前核等处。密集的心钠素免疫反应阳性纤维布于下丘脑室旁核,终纹床核及终板血管器官等处。心钠素在脑内的分布状态提示心纳素可能具有中枢性调节水电解质平衡及心、血管的功能,此外,亦可能参与下丘脑—垂体系神经内分泌调节的作用。  相似文献   
107.
Seventy-five patients with resistant acute leukemia or lymphoma received high-dose cyclophosphamide and etoposide to explore the activity of this combination in resistant hematologic malignancies, and to determine the maximum doses of these drugs that can be combined without bone marrow transplantation. Etoposide was administered over 29 to 69 hours by continuous infusion corresponding to total doses of 1.8 g/m2 to 4.8 g/m2. Cyclophosphamide, 50 mg/kg/d, was administered on 3 or 4 consecutive days total 150 to 200 mg/kg ideal body weight). At all dose levels myelosuppression was severe but reversible. Mucosal toxicity was dose-limiting with the maximum tolerated dose level combining etoposide 4.2 g/m2 with cyclophosphamide 200 mg/kg. Continuous etoposide infusion produced stable plasma levels that were lower than would be achieved after administration by short intravenous infusion, and this could explain our ability to escalate etoposide above the previously reported maximum tolerated dose. There were 28 complete (35%) and 12 partial (16%) responses. Median duration of complete response (CR) was 3.5 months (range 1.1 to 20+). Seventeen of 40 patients (42%) with acute myelogenous leukemia (AML) achieved CR, including 6 of 20 (30%) with high-dose cytosine arabinoside resistance. We conclude that bone marrow transplantation is not required after maximum tolerated doses of etoposide and cyclophosphamide. This regimen is active in resistant hematologic neoplasms, and the occurrence of CR in patients with high-dose cytosine arabinoside-resistant AML indicates a lack of complete cross-resistance between these regimens.  相似文献   
108.
Summary In view of the variety of 3D representation techniques, a clinical study was carried out in order to evaluate their respective usefulness. It appears that a single technique cannot be claimed to be valid for all clinical situations and that a combination of representations brings more relevant information. Among the different techniques a clear delineation must be established between those which allow the accurate definition of landmarks (multiplanar reformation, surface representation), and those which do not (integral shading, reconstructed radiology). The main point is the possibility to recognize anatomical landmarks on these latter modes and to choose oblique cut planes in relation to them. Visualization quality is strongly dependent upon the acquisition protocol which must provide a spatial resolution as isotropic as possible.
Une revue de différents modes de visualisation en haute résolution d'un objet volumique avec des applications
Résumé Face à la variété des techniques de représentation 3D une étude clinique a été conduite pour évaluer leurs utilités respectives. Il apparait qu'une technique unique ne peut pas convenir à toutes les situations cliniques et qu'une combinaison de différents modes de présentation apporte une information plus pertinente. Parmi les différentes techniques une distinction claire doit être établie entre celles qui autorisent la prise de repères précis (reformatage multiplanaire, représentation de surface), et celles qui ne le permettent pas (ombrage intégral, radiologie reconstruite). Le point principal est la possibilité de reconnaître des repères anatomiques sur ces derniers modes et de choisir des plans de coupe en relation avec eux. La qualité de la visualisation dépend étroitement du protocole d'acquisition qui doit fournir une résolution aussi isotrope que possible.
  相似文献   
109.
110.
Solitary bronchioloalveolar carcinoma: CT criteria   总被引:14,自引:0,他引:14  
The computed tomographic (CT) scans of 30 patients with solitary bronchioloalveolar carcinoma were reviewed. Common features at CT included the peripheral or subpleural location of a pulmonary mass (25 cases), pseudocavitation (18 cases), heterogeneous attenuation (17 cases), irregular margins forming a star pattern (22 cases), and pleural tags (21 cases). Using these CT criteria, four independent observers attempted to identify cases of bronchioloalveolar carcinoma from a larger sample of lung cancers and benign lesions by categorizing a series of test cases into four probability categories. Although the bronchioloalveolar carcinomas were correctly ranked in the two highest probability categories 75% of the time (in 45 of 60 cases), there was considerable overlap with other lung lesions, particularly with adenocarcinoma and large cell undifferentiated carcinoma. However, even though the typical features of bronchioloalveolar carcinoma are not invariable or highly specific, they are characteristic enough to suggest the 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