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   10478篇
  免费   527篇
  国内免费   90篇
耳鼻咽喉   96篇
儿科学   194篇
妇产科学   134篇
基础医学   1241篇
口腔科学   240篇
临床医学   680篇
内科学   2985篇
皮肤病学   157篇
神经病学   672篇
特种医学   373篇
外科学   1723篇
综合类   66篇
预防医学   322篇
眼科学   225篇
药学   658篇
  1篇
中国医学   15篇
肿瘤学   1313篇
  2023年   67篇
  2022年   118篇
  2021年   245篇
  2020年   159篇
  2019年   152篇
  2018年   257篇
  2017年   181篇
  2016年   222篇
  2015年   227篇
  2014年   322篇
  2013年   349篇
  2012年   581篇
  2011年   670篇
  2010年   369篇
  2009年   278篇
  2008年   496篇
  2007年   595篇
  2006年   552篇
  2005年   542篇
  2004年   518篇
  2003年   479篇
  2002年   530篇
  2001年   260篇
  2000年   240篇
  1999年   220篇
  1998年   117篇
  1997年   100篇
  1996年   83篇
  1995年   108篇
  1994年   87篇
  1993年   89篇
  1992年   195篇
  1991年   144篇
  1990年   163篇
  1989年   172篇
  1988年   131篇
  1987年   136篇
  1986年   124篇
  1985年   117篇
  1984年   81篇
  1983年   68篇
  1982年   29篇
  1980年   36篇
  1979年   59篇
  1978年   35篇
  1977年   39篇
  1975年   30篇
  1972年   31篇
  1971年   27篇
  1970年   29篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
A case of glioblastoma arising in the pons of a 14-year-old boy in whom transsynaptic degeneration was found in the inferior olivary nucleus is reported. The tumor occupied most of the pons including the tegmental tract and invaded into the midbrain, medulla oblongata, cerebellar peduncles, thalamus, basal ganglia, and meninges. The right inferior olivary nucleus was devoid of the tumorous lesion, but many neurons were severely vacuolated. An im-munohistochemical study using glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), and S-100 protein was performed. GFAP and S-100 protein were positive in the reactive glia of the nucleus and NSE gave a faint reaction in some degenerated neurons. These degenerative changes found in neurons of the inferior olivary nucleus were considered to be transsynaptic degeneration due to the destruction of the tegmental tract at the pons and of cerebellar peduncles by invasive pontine glioblastoma. ACTA PATHOL. JPN. 35: 1495–1500, 1985.  相似文献   
52.
53.
Hepatitis B virus (HBV), with a G-to-A point mutation at nucleotide 83 in the precore region (mutant HBV83), accounts for most cases of hepatitis B e antigen (HBeAg)-defective HBV. However, it is still not clear how mutant HBV83 is associated with HBe seroconversion. Twenty-six HBeAgpositive patients with chronic hepatitis B who received oral prednisolone (30 mg/day) for 3 weeks were studied to clarify the prevalence of mutant HBV83 during the treatment using polymerase chain reaction with a restriction fragment length polymorphism assay. Twelve (46%) patients seroconverted to anti-HBe 1 year after treatment, whereas 14 (54%) did not. The proportion of mutant HBV83 to whole HBV remained unchanged in both groups during an acute exacerbation induced by withdrawal of corticosteroids. Among 12 anti-HBe-0seroconverted patients, five (56%) of nine patients with only wild-type HBV at baseline developed detectable levels of mutant HBV83 while all three patients with a mixed viral population of wild-type HBV and mu tant HBV83 at baseline developed a higher pro portion of mutant HBV83 one year after treat ment. In contrast, these changes were observed in only one (14%) of seven who failed to seroconvert. The results indicate that a flare-up of hepa titis precedes emergence or selection of mutant HBV83, followed by HBe seroconversion in patients with chronic hepatitis B. © 1995 WiIey-Liss, Inc.  相似文献   
54.
A new mutation in the serine-threonine klnase domain of the transforming growth factor β type II receptor (TGFpRII) was found in a case of diffuse, B cell non-Hodgkin's lymphoma of the stomach. A mfssense mutation (ACA to GCA, Thr to Ala) was detected In exon 5, and a wild type allele was also present. This Is the first naturally occurring mutation in the klnase domain of this gene identified in human primary lymphoma. The replication error at three loci was negative, and the poly A tract of exon 3, which is frequently a target of mismatch repair genes, was intact. Malignant lymphoma of B cell origin in the stomach Is an addition to an expanding catalogue of tumors with TGFβRII alterations, and the biological sequelae of the change in the functional domain and the clinical characteristics of the patient in this study are intriguing.  相似文献   
55.
The localization of intraglomerular deposits of fibrin (Fb)/fibrinogen (Fg)-related antigen (FRA) in children with various glomerular diseases was determined by an immunohistopathologic method using an anti-Fg antibody capable of detecting FRA, an anti-D-dimer antibody capable of detecting crosslinked Fb (XLFb) and its derivatives (XLFbDP), and by a method using the effect of monochloroacetic acid (MCA) treatment on kidney sections. In proliferative glomerulonephritis (PGN), XLFbs were detected within the capillaries and extension beyond the mesangium was seen in severe PGN. The FRA within the mesangium of minimal or mild PGN was composed of the non-XLFb substance. The FRA within Bowman's space of most PGN had disappeared after MCA treatment, suggesting a non-XLFb substance. The presence of FRA within electron-dense deposits (EDD) suggested that FRA deposits are associated with immune-complex deposits in the glomeruli.  相似文献   
56.
Centromere protein F (CENP-F) expression (localization and characteristics) in relation to tumor clinicopathological parameters was immunohistochemically examined and evaluated in 47 archival biopsy specimens of buccal and gingival squamous cell carcinomas (SCC). Centromere protein F expression was detected in 79% of the samples. An increase in the labeling index (LI) with WHO grading was obtained ( P  < 0.05). Correlations were obtained between the CENP-F LI and tumor size ( P  < 0.05). Immunoelectron microscopy showed CENP-F nuclear staining as punctate or fine dots. The present study shows that CENP-F expression and detection of a more specific cell subpopulation presents a theoretical advantage for the analysis of the precise cell cycle of G2 to M cells, compared to Ki-67.  相似文献   
57.
Studies have suggested that psoriasis vulgaris is mediated by type 1 T cells. In this study, we examined both chemokine receptor expression and intracellular cytokine production by circulating T cells to check the type 1/type 2 balance in psoriasis. CCR4+ and CXCR3+ T cells predominantly produced interleukin-4 and interferon-, respectively. The frequency of interferon--producing cells and that of CXCR3+ cells in circulating CD4+ T cells were similar for psoriatic patients and healthy control subjects. By contrast, the frequency of CCR4+CD8+ T cells and CCR4/CXCR3 ratio in circulating CD8+ T cells were significantly higher in psoriatic patients than in healthy control subjects. Analysis of intracellular cytokine production also indicated relative increase of type 2 CD8+ T (Tc2) cells in peripheral blood from psoriatic patients. The frequency of circulating Tc2 cells directly correlated with Psoriasis Area and Severity Index. Immunohistochemical analysis showed that not only CXCR3+CD8+ T cells but also a similar number of CCR4+CD8+ T cells infiltrated the psoriatic epidermis and dermis. Our findings suggest an increase in Tc2 cell number in blood from psoriatic patients, and the association of Tc2 cells with inflammation in psoriasis.  相似文献   
58.
The increasing complexity of diseases and advancing medical technologies have recently raised the number of test items and their use. This has caused each department to ask for clinical support by medical technologists, including consultation services on clinical laboratory tests in Japan. Under these circumstances, we think it is necessary to consider a Japanese education system for medical technologists to foster people with advanced ability capable in providing adequate clinical support. It is important that we study medical technologist systems and education systems superior to than ours. Therefore, to investigate the state of the Japanese education system for medical technologists, we conducted a comparison between the medical technologist systems and education systems in foreign countries and those of Japan. The social background in which medical technologists are positioned, their scope of work, and the education systems overseas are different from Japan on many points and we were given many suggestions for what a system in Japan should be like.  相似文献   
59.
Morphological studies of secondary palate formation, with special reference to the development of rugae, were carried out on Jcl:ICR mouse embryos. Three rugae were observed on the anterior part of the future oral surface of the vertically developing palatal shelves in 13-day embryos. Rugae increased in number as the development of the palatal shelves proceeded, and five to six prominent rugae were observed in 14-day embryos just prior to shelf elevation. The folding of these five to six rugae progressed in conjunction with the formation of a sharp, valley-like groove at the base of the anterior two-fifths of the vertical palatal shelves. As palatal shelves elevated, the groove disappeared gradually, and, accordingly, the folding of rugae loosened. In the groove region, the superficial epithelial cells were roundish, while the basal ones were elongated. Such characteristic features were no longer observed when the disappearance of the groove was completed. Eight rugae were observed on the future hard palate of 14-day embryos with already completed palatal fusion. An additional ruga was frequently found in 15-day embryos, and the pattern then was almost the same as that of an adult. Epithelial thickening and condensation at the rugae region, as well as mesenchymal condensation under the epithelium of the rugae, were confirmed in embryos both before and after elevation of the palatal shelves. There is a possibility that these structural characteristics observed in the epithelial and mesenchymal cells of the rugae and groove regions may be related to palatal shelf elevation.  相似文献   
60.
Prostate cancer is a major cause of cancer death among elderly men in America, Europe, and Japan. However, the molecular mechanism of carcinogenesis is not yet well characterized. Frequent loss of heterozygosity (LOH) on chromosome 10q was reported in prostate cancer, and a candidate tumor suppressor gene, PTEN, was isolated on chromosome band 10q23.3. To investigate the genetic alterations of PTEN, we examined 45 primary prostate cancer specimens. LOH at the PTEN locus was observed in two (11.1%) of 18 tumors. However, no mutations were observed in any of the primary prostate cancers. These data suggest that mutation of the PTEN gene does not play a major role in prostate carcinogenesis of Japanese patients. Received: February 6, 1998 / Accepted: July, 3, 1998  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