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   608篇
  免费   32篇
  国内免费   1篇
耳鼻咽喉   9篇
儿科学   25篇
妇产科学   25篇
基础医学   85篇
口腔科学   12篇
临床医学   62篇
内科学   107篇
皮肤病学   1篇
神经病学   57篇
特种医学   21篇
外科学   75篇
预防医学   42篇
眼科学   30篇
药学   54篇
肿瘤学   36篇
  2024年   2篇
  2023年   3篇
  2022年   3篇
  2021年   11篇
  2020年   17篇
  2019年   11篇
  2018年   14篇
  2017年   15篇
  2016年   15篇
  2015年   11篇
  2014年   17篇
  2013年   31篇
  2012年   45篇
  2011年   32篇
  2010年   26篇
  2009年   26篇
  2008年   32篇
  2007年   39篇
  2006年   40篇
  2005年   40篇
  2004年   46篇
  2003年   32篇
  2002年   28篇
  2001年   10篇
  2000年   10篇
  1999年   10篇
  1998年   5篇
  1997年   5篇
  1996年   2篇
  1995年   3篇
  1994年   4篇
  1993年   3篇
  1992年   5篇
  1991年   6篇
  1990年   3篇
  1989年   3篇
  1988年   4篇
  1987年   4篇
  1986年   3篇
  1985年   3篇
  1984年   3篇
  1983年   3篇
  1982年   3篇
  1981年   1篇
  1980年   2篇
  1979年   2篇
  1977年   1篇
  1976年   3篇
  1975年   2篇
  1973年   2篇
排序方式: 共有641条查询结果,搜索用时 10 毫秒
21.
22.
23.
OBJECTIVES: Urine cytology is the gold standard in the diagnosis and follow-up of bladder cancer. Cytology, however, exhibits variable sensitivity depending on tumour grade and interpretation of urine specimens is highly dependent on the skill of the examiner. Positive cytology, classes IV and V by Papanicolaou classification, is a strong predictor for coexisting or subsequent malignancy, while the role of suspicious cytology, class III, is controversial. The objective of the study was to evaluate the role of the suspicious finding in cytological analysis, and whether it should be considered as a negative or positive sign for coexisting malignancy. MATERIAL AND METHODS: Six hundred and fifty-two consecutive patients with bladder cancer were studied in a prospective multicenter trial. One hundred and fifty-one of the patients were newly diagnosed, and the remaining 501 patients were under follow-up. A voided urine sample was obtained prior to TURB or prior to routine follow-up cystoscopy in those under the surveillance and split for culture and cytology. The cytopathological results were analyzed by a central review and only patients with samples available for review analysis were included. Sensitivity and specificity, as well as positive (PPV) and negative (NPV) predictive values of urine cytology were calculated by classifying the class III samples as negative or positive. RESULTS: A total of 570 patients were evaluable. One hundred and twenty nine (22.6%) were newly diagnosed and 441 were under follow-up, of whom 117 (26.5%) had recurrence. Cytology was classified as suspicious in 33/129 (25.6%) patients with primary tumour, and in 41/441 (9.3%) of those under the follow-up, of whom 20 (48.8%) had recurrence. Sensitivity increased from to 31.0% to 56.6% in primary tumours (p < 0.001) and from 17.8% to 34.7% in recurrent tumours (p < 0.001) if class III was determined as positive, whereas the specificity decreased from 96.6% to 90.1% (p < 0.001). Accordingly, the NPV increased from 76.3% to 79.1% and the PPV decreased from 65.6% to 56.2%. CONCLUSIONS: The poor sensitivity of voided urine cytology improved significantly when suspicious samples were determined as positive while the specificity remained high, a clear advantage compared with most of the new tumour marker tests. In addition, nearly half of the follow-up patients with suspicious class III cytology had recurrence implying that this patient category is at substantial risk for co-existing malignancy. Therefore, it is recommended that suspicious class III cytology together with class IV and V specimens should be considered positive.  相似文献   
24.
25.
Summary In order to study the morphological basis of the increased permeability of the capillaries of the iris in neuroparalytic keratitis the ophthalmic division of the trigeminal nerve in the cat was denervated using a stereotactic method. The homolateral iris was studied by electron microscopy three days after denervation. Abnormally large pinocytotic vacuoles were observed in the endothelial cells of the iris capillaries and the intercellular junctions of the endothelial cells showed widened inter-cellular space and macula occludens. These ultrastructural changes may explain the protein leakage into the anterior chamber in neuropyralytic keratitis.
Zusammenfassung Um die morphologische Grundlage der erhöhten Permeabilität der Iriskapillaren bei Keratitis neuroparalytica zu untersuchen, wurde der Augenast des Trigeminus bei der Katze stereotaktisch denerviert. Drei Tage danach zeigten sich im Elektronenmikroskop abnorm umfangreiche pinocytotische Vakuolen in den Endothelien der Kapillaren der Regenbogenhaut und erweiterte Intercellulärräume mit Macula occludens. Hierin kann der Übertritt von Protein in das Kammerwasser bei Keratitis neuroparalytica erklärt werden.


Submitted in part to the meeting of the European Club for Ophthalmic Fine Structure in London, April 19, 1974 (M. S.).

Supported by a grant from the Finnish Medical Foundation and the Instrumentariumin Tiedesäätiö Foundation (M. S.).  相似文献   
26.
27.
The apolipoprotein E (APOE) polymorphism is associated with neurodegenerative diseases. Its role regarding psychiatric disorders is controversial. It has been suggested to affect antidepressant treatment response and response to electroconvulsive therapy (ECT). In the present study, the association between APOE polymorphism and response to ECT in 119 patients with major depressive disorder was investigated. Moreover, a relation between APOE polymorphism and the age of onset of depression as well as the cognitive outcome of ECT was studied. In the whole population, no association was found between APOE polymorphism and response to ECT. However, in nonpsychotic patients, the epsilon2 allele tended to be more frequent in responders than nonresponders. Earlier onset of depression was observed in the patients with epsilon4 allele in late-life depression. There was no association between the APOE genotype and the cognitive change caused by ECT in the population as a whole. In women, however, epsilon2 allele may play a protective and epsilon4 allele a deleterious role in cognition during ECT.  相似文献   
28.
OBJECTIVE: Emotion regulation has been associated with good, and dysregulation with poor subjective health; but it is unclear if emotion regulation is related to metabolic syndrome. METHODS: Associations between the metabolic syndrome factor (systolic and diastolic blood pressure, waist circumference, high-density lipoprotein, triglycerides, and glucose), emotion regulation (the strategies of repair and maintenance, self-perceived emotion regulation) and dysregulation (emotional ambivalence); and subjective health (self-rated health and psychosomatic symptoms) were studied using a structural equation modelling (SEM) approach. The participants (96 women, 85 men) were drawn from the Jyv?skyl? Longitudinal Study of Personality and Social Development (JYLS). RESULTS: High repair was associated directly to the low metabolic syndrome factor, while high maintenance, high self-perceived emotion regulation, and low emotional ambivalence were related indirectly to the low metabolic syndrome factor through good subjective health. CONCLUSIONS: Successful emotion regulation may have an association not only with the subjective experience of health, but also with physiological regulation systems, leading to a reduced risk for metabolic syndrome.  相似文献   
29.
BACKGROUND AND PURPOSE: In MR spectroscopic imaging (MRSI), the volume-selection profiles of metabolites differ from each other. These differences cause variations in metabolite intensities, which are particularly prominent when the hippocampi are evaluated. We hypothesize that the errors arising from these effects cause notable artifact when temporal lobe epilepsy (TLE) is lateralized with MRSI. METHODS: We examined a metabolite phantom, control subjects, and patients with TLE by using MRSI. We calculated the error arising from the different volume-selection profiles of metabolites in vitro and evaluated this correction in the examination of the control subjects and in the lateralization of epilepsy in the patients. RESULTS: Without a correction, a considerable error in the metabolite content existed, even deep inside the spectroscopic volume of interest. The result was false asymmetry (P < .008) in the hippocampi of control subjects. Among the 11 patients, TLE was correctly lateralized in three only after the correction was made, and in one, TLE was incorrectly lateralized. CONCLUSION: The volume-selection profiles of N-acetylaspartate, choline, and creatine differ enough to cause a significant error, even in the metabolite ratios, when patients with TLE are examined with MRSI. We propose a simple phantom method to correct for this error without a need to modify the pulse sequence.  相似文献   
30.
Chorionic gonadotropin (CG) is an essential signal in establishment and maintenance of pregnancy in humans and higher primates. A G-to-A transition in exon 3 of human CGbeta gene 5, changing the naturally occurring valine residue to methionine in codon 79 (Val(79)Met) has been reported at carrier frequency 4.2% in a random population from the Midwest of the United States. The biological activity of the variant hCG was similar to that of wild-type (WT) hCG. However, the Val(79)Met beta-subunit displayed impaired ability to assemble with alpha-subunit, and the amount of hCG alpha/beta heterodimers formed and secreted by transfected cells was seriously impaired in the previous study. Because of these functional implications we found it important to study the occurrence of the Val(79)Met hCGbeta variant in other populations. By using a PCR-RFLP method, a search for the Val(79)Met hCGbeta variant was carried out on a total of 580 DNA samples from five European populations (Finland, Denmark, Greece, Germany and the UK). The results demonstrated an absence of the polymorphism in these populations. Hence, the naturally occurring variant (Val(79)Met) of the hCGbeta gene 5, found previously at high frequency in the US, is clearly less common, or absent, in the European populations studied.  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