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   2485篇
  免费   136篇
  国内免费   16篇
耳鼻咽喉   6篇
儿科学   87篇
妇产科学   61篇
基础医学   400篇
口腔科学   107篇
临床医学   189篇
内科学   568篇
皮肤病学   46篇
神经病学   194篇
特种医学   61篇
外国民族医学   1篇
外科学   280篇
综合类   24篇
一般理论   1篇
预防医学   246篇
眼科学   23篇
药学   158篇
中国医学   18篇
肿瘤学   167篇
  2024年   5篇
  2023年   26篇
  2022年   69篇
  2021年   91篇
  2020年   68篇
  2019年   59篇
  2018年   88篇
  2017年   47篇
  2016年   64篇
  2015年   85篇
  2014年   81篇
  2013年   115篇
  2012年   158篇
  2011年   193篇
  2010年   96篇
  2009年   66篇
  2008年   120篇
  2007年   127篇
  2006年   137篇
  2005年   110篇
  2004年   103篇
  2003年   96篇
  2002年   79篇
  2001年   37篇
  2000年   54篇
  1999年   54篇
  1998年   27篇
  1997年   18篇
  1996年   22篇
  1995年   19篇
  1994年   11篇
  1993年   15篇
  1992年   42篇
  1991年   25篇
  1990年   33篇
  1989年   23篇
  1988年   20篇
  1987年   21篇
  1986年   21篇
  1985年   17篇
  1984年   12篇
  1983年   11篇
  1982年   4篇
  1979年   8篇
  1978年   6篇
  1977年   8篇
  1976年   5篇
  1975年   7篇
  1974年   6篇
  1971年   9篇
排序方式: 共有2637条查询结果,搜索用时 31 毫秒
31.
PURPOSE: The aim of the study is to describe a case of suspected endotoxin-induced uveitis associated with septic endogenous endophthalmitis followed by antibiotic-induced endotoxemia. METHODS: The human leukocyte antigen (HLA) typing of peripheral leukocytes was studied by lymphocytotoxicity technique. Histological and immunohistochemical studies of paraffin embedded specimen were conducted. RESULTS: Findings of HLA typing revealed positive reaction for B 51, Cw 3, DR 8, DR 11, DQ 3. The vitreous body of an eviscerated eye was occupied by the non-specific granulomatous tissue, composed of fibroblast, plasma cells, and Sudan black staining positive foamy cells, including melaniferous phagocytes, identified as CD 68 positive macrophage. CONCLUSION: It is suggested that antibiotic-induced endotoxemia of a patient with septic endogenous endophthalmitis produced endotoxin-induced uveitis under an upregulation of HLA and endotoxin activated macrophages may release cytokines, followed by fibrin formation and subsequent granuloma.  相似文献   
32.
INTRODUCTION: Knowledge accumulation is overfilling the thematic content of medical graduation. Medical Schools must be alert to define a minimal content related with the most frequent disturbs. We intent to suggest topics for the minimal content, to the program of Neurology in medical graduation. METHOD: 1. To identify the places where young doctors are working outside the School Hospital (SH): we analysed the answers of the letters sent to 6415 resident - doctors (RD) in S?o Paulo's State and we made personal interview with 201 RD. 2. To verify the most frequent neuropsychiatric disturbs (ND) in the population: we made the analysis of the patient's diagnostic records in emergency room of three institutions: Municipal of Taubaté-SP, Municipal of S?o José dos Campos-SP and Faculty of Medicine of S?o Paulo Santa Casa de Misericórdia. RESULTS: 1. The RD are young and, outside the SH, they work in other emergency services. 2. The most frequent diagnosis in institutions were listed: alcoholism, cerebrovascular disease, coma, cranial trauma, dementia, dizziness, epilepsy, facial paralysis, faint, headache, hemiplegia or paraplegia, meningitis, others paralysis, periferical neuropathy and psychiatric disorders. CONCLUSIONS: Those diagnostics most frequent are relevant topics of the programmatic content to the program of Neurology in medical graduation.  相似文献   
33.
We herein describe thallium-201 single photon emission tomography (T1-201 SPECT) findings in three cases with intracranial angioma. One of the lesions which was associated with chronic encapsulated intracerebral hematoma showed moderate accumulation of T1-201, but, others demonstrated no accumulation. The usefulness and limitations of T1-201 SPECT in differential diagnosis of intracranial mass lesions are discussed.  相似文献   
34.
Spontaneous regression and maturation of neuroblastoma (NB) are well documented and occur frequently in infants, including those detected by mass screening. To seek histologic clues for regression/maturation in mass-screened NB, clinicopathologic features of 12 tumors that were resected after 2 to 18 months of untreated observation were reviewed. Unobserved screened and age-matched unscreened patients were also studied. To evaluate the possible important role of apoptosis, apoptotic cells were detected by in situ deoxyribonucleic acid (DNA) nick end labeling and immunohistochemical stain for activated caspase-3. Nests with a varying degree of reduced cellularity ("less cellular" and "hypocellular" nests) were common in patients younger than 18 months of age, and were rare in older patients. Two characteristic cells, which have not been focused previously, were frequent, especially in the hypocellular nests. One showed amorphic eosinophilic cytoplasm with pyknotic nuclei and the other contained plump cytoplasm with well-maintained nuclei. These cells were also observed in 89% of the unobserved screened NBs and 79% of the age-matched unscreened patients with good outcome, whereas they could not be confirmed in any of the age-matched unscreened NBs with poor outcome. The amorphic and plump cells were negative for activated caspase-3 and in situ DNA nick end labeling. From these results, the authors hypothesize that these cells most likely represent a degenerative process, in either a state before the activation of caspase-3 or a caspase-independent form of cell death. The presence of less cellular and hypocellular nests with amorphic/plump cells may serve as one of the important clues in predicting tumor prognosis.  相似文献   
35.
The neurotrophin nerve growth factor (NGF) is a major regulator of peripheral and central nervous system development. Serum NGF was measured in normally developing control children (n=26) and in individuals affected by congenital syndromes associated with learning disability: either Williams syndrome (WS; n=12) or Down syndrome (DS; n=21). Participants were assessed at three distinct developmental stages: early childhood (2 to 6 years), childhood (8 to 12 years), and adolescence (14 to 20 years). A sample was taken only once from each individual. Serum NGF levels were markedly higher in participants with WS, than DS and control participants. In addition, different developmental profiles emerged in the three groups: while in normally developing individuals NGF levels were higher in early childhood than later on, children with WS showed constantly elevated NGF levels. When compared to control participants, those with DS showed lower NGF levels only during early childhood. Neuropsychological assessment confirmed previously reported differences among the three groups in the development of linguistic/cognitive abilities. Some features of individuals with WS, such as hyperacusis and hypertension, could be related to high-circulating NGF levels.  相似文献   
36.
Mizusawa K  Iigo M  Masuda T  Aida K 《Neuroreport》2000,11(16):3473-3477
Melatonin production in the pineal organ and retina is controlled by both light-dark cycles and a circadian clock via the oscillating activity of arylalkylamine N-acetyltransferase (AANAT) in most vertebrates. However, this clock regulation is absent in the rainbow trout (Oncorhynchus mykiss) pineal organ: the trout has two different AANAT genes (AANAT1 and AANAT2), and AANAT2 mRNA levels in the pineal organ did not exhibit circadian oscillation In this study, we confirmed by RT-PCR analysis that AANAT1 is expressed only in the retina, while AANAT2 is expressed in the pineal organ and brain. Real-time quantitative PCR analysis demonstrated that AANAT1 mRNA levels in the retina exhibited daily variations with high levels during the dark phase under light-dark cycles, but kept high and low titers under constant darkness and constant light, respectively. Thus, AANAT1 gene expression in the trout retina is regulated not by a circadian clock but by lighting conditions.  相似文献   
37.
Although genetic and environmental factors have been identified in the etiology of thyroid cancer, the specific genetic implications in sporadic thyroid tumors are poorly understood but, as in other common cancers, low-penetrance susceptibility genes are believed to be crucial in the tumorigenesis processes. Here, we have carried out a case-control study to investigate whether there is an association between THRA1 CA repeat or BAT-40 A repeat polymorphisms and thyroid cancer risk. The THRA1 repeat resides in the thyroid hormone receptor-alpha1 gene, which is associated with thyroid cancer and whose expression depends on the THRA1 repeat size. We also analyzed the BAT-40 repeat that maps to chromosome 1, a region known to be involved in thyroid cancer. This repeat is located in the 3-beta-hydroxysteroid dehydrogenase gene that is associated with prostate cancer susceptibility. The THRA1 repeat was genotyped in 212 thyroid cancer patients and 141 controls of a Spanish population. From these individuals, 207 patients and 138 controls were also analyzed for the BAT-40 marker. No significant difference in the THRA1 allele distribution between patients and controls was found, although short alleles (<128 bp) might have some protective effect on thyroid cancer risk of carriers (odds ratio, 0.50; 95% confidence interval, 0.22-1.13; P = 0.094). By contrast, the BAT-40 allele distribution in patients was significantly different with respect to control (P = 0.035). Essentially, the difference were found in the genotypes involving the 111- to 115-bp allele range, which seem to be associated with a protective effect on thyroid cancer susceptibility in the studied population (odds ratio, 0.18; 95% confidence interval, 0.01-0.57; P = 0.02). Therefore, our results indicate that the BAT-40 containing region and to a less extend the thyroid hormone receptor-alpha1 gene are related to thyroid cancer susceptibility. To our knowledge, this is the first study reporting the identification of genetic factors for thyroid cancer susceptibility.  相似文献   
38.
39.
40.
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