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   22330篇
  免费   1158篇
  国内免费   201篇
耳鼻咽喉   251篇
儿科学   493篇
妇产科学   252篇
基础医学   2842篇
口腔科学   366篇
临床医学   1365篇
内科学   6297篇
皮肤病学   424篇
神经病学   1616篇
特种医学   929篇
外科学   3801篇
综合类   80篇
预防医学   505篇
眼科学   433篇
药学   1239篇
中国医学   39篇
肿瘤学   2757篇
  2023年   165篇
  2022年   352篇
  2021年   617篇
  2020年   304篇
  2019年   399篇
  2018年   574篇
  2017年   469篇
  2016年   522篇
  2015年   557篇
  2014年   683篇
  2013年   867篇
  2012年   1368篇
  2011年   1563篇
  2010年   941篇
  2009年   812篇
  2008年   1377篇
  2007年   1452篇
  2006年   1484篇
  2005年   1492篇
  2004年   1486篇
  2003年   1350篇
  2002年   1329篇
  2001年   288篇
  2000年   246篇
  1999年   285篇
  1998年   294篇
  1997年   244篇
  1996年   181篇
  1995年   191篇
  1994年   168篇
  1993年   151篇
  1992年   147篇
  1991年   150篇
  1990年   109篇
  1989年   127篇
  1988年   108篇
  1987年   68篇
  1986年   74篇
  1985年   73篇
  1984年   75篇
  1983年   68篇
  1982年   44篇
  1981年   50篇
  1980年   44篇
  1979年   38篇
  1978年   41篇
  1977年   32篇
  1975年   25篇
  1969年   20篇
  1968年   20篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Summary This report presents a variant of Gerstmann-Sträussler syndrome (GSS). A 53-year-old female had developed slowly progressive dementia and atactic gait since the age of 45. No myoclonic jerks and periodic synchronous discharges were observed throughout the illness. The neuropathological study revealed that many amyloid plaques and widespread Alzheimer's neurofibrillary tangles (NFTs) appeared in the cerebral cortex. Characteristically, the plaques reacted with anti-prion protein and none of them reacted with anti- protein, and they were made of many components, including amyloid cores, macrophages laden with lipid granules and/or degenerated neurites. Neuropil threads were seen mainly in amyloid plaques. Moreover, plaques appeared which were confluent and laminar in arrangement in the fifth and sixth cortical layers and had a close relationship to the neuronal loss. There was no spongiform change in the cerebral cortex or cerebellum. The cerebellum was almost intact except for a few amyloid plaques. Ultrastructurally, some of the plaques simulated kuru plaques and others had many degenerated neurites possessing paired helical filaments and other accumulated organelles. GSS has been proposed to include cases with progressive ataxia, dementia and massive multifocal plaques in the brain with or without cerebral spongiform changes. The case presented here is a very peculiar case of GSS. Recently, similar cases have been reported in some large families, diagnosed as familial Alzheimer's disease. These cases may be a telencephalic form with numerous NFTs of GSS.  相似文献   
82.
Patients with acute (2,569) and chronic (957) leukemia diagnosedat 19 institutes took part in the study on the "MultidisciplinaryTreatment of Leukemia" between 1971 and 1985 and were investigatedretrospectively. By dividing the 15 years into three five-yearperiods, we were able to compare patient ratios in the differentperiods. The proportions of acute to chronic leukemia casesshowed no obvious change; however, the proportions of casesdiagnosed as acute lymphocytic leukemia in acute leukemia showeda significant increase. The main chemotherapeutic drugs usedduring the three time periods were cytarabine or its analogues,the anthracyclines, 6-mercaputopurine and prednisolone, againstacute myelogenous leukemia, and the vinca alkaloids, prednisoloneand the anthracyclines against acute lymphocytic leukemia. Therate of complete remission from acute myelogenous leukemia mademarked progress, from 45.1% during 1971–1975 to 62.3%during 1981–1985, but that of acute lymphocytic leukemiashowed no significant progress, being 65% during 1971–1975and 69.7% during 1981–1985. The durations of remission,however, and the survival times for patients with acute lymphocyticleukemia, as well as for those with acute myelogenous leukemia,became significantly longer over the three periods. Median survivaltimes from chronic myelocytic leukemia were 37–40 mo inall three periods, showing no progress. There was a better prognosisin cases of chronic myelocytic leukemia with, than without,Philadelphia chromosome. Except for a low incidence of chroniclymphocytic leukemia in Japan, adult leukemia patients' characteristicsand prognoses seem to be almost the same in Japan as in theU.S.A. and Europe.  相似文献   
83.
A4-moth-old male infant predisposed to allergic dermatitis acquired widespread eczema vaccinatum by contacts with a recently vaccinated sibling. He died of acute purulent peritonitis following a perforation of multiple duodenal ulcers. Fluorescence immunocytochemical and electron microscopic studies on the skin lesions revealed the presence of viral antigens and numerous virus particles compatible morphologically with those of the mature form from the same batch of smallpox vaccine given to the sibling. A large number of virus particles in the developmental form were also predominantly scattered in the cytoplasm of cells at the stratum malpighii of the epidermis as well as in neutrophils and macrophages in the skin lesions. The virus isolation from the skin lesions was done by using the HeLa cells and the human embryonic lung fibroblasts. No abnormal laboratory data were noted in immunoglobulins. On the basis of atrophy of the thymus and other lymphatic tissues and an appearance of large pyroninophilic cells in association with blastoid transformation, the authors discussed a possible participation of the disturbance of cellular immunity secondary to the virus infection in the development of the disease. ACTA PATH. JAP. 29 : 435–455, 1979.  相似文献   
84.
To demonstrate ultrastructural events in the early phase of hepatic metastasis of human colon carcinoma, we intrasplenically injected a highly metastasizable, human colon carcinoma cell line LM-H3 (1 x 10(6) cells) into nude mice, and electron microscopically investigated the hepatic metastasis. At 24 h, tumor cells adhered to the endothelial wall of terminal portal venules and periportal sinusoids. At 48-72 h, after extravasation, they deeply invaded the hepatic cell plate and the interstitial tissue of the portal tract, in which they underwent proliferation and made the metastatic foci. Tumor cells were linked with each other or with surrounding hepatocytes by desmosomes. Desmosomes were maintained during the mitosis. When invading tumor cells were exposed to the bile canaliculi, they generated microvilli on the surface. Microvilli were also formed at the luminal surface of intracytoplasmic inclusions. In the interstitial tissue of the portal tract, tumor cells were closely associated with fibroblasts. However, no junctional specializations were seen between them. The present study demonstrated that human colon carcinoma cell line LM-H3 formed desmosomes with hepatocytes soon after invasion of the hepatic cell plate, suggesting the regulatory role of an interaction with hepatocytes in the growth of metastatic foci within the liver parenchyma.  相似文献   
85.
86.
As previously reported (I. Yano, I. Tomiyasu, S. Kitabatake, and K. Kaneda, Acta Leprologica 2:341-349, 1984), Nocardia rubra, one of the nonpathogenic actinomycetes, possesses three classes of mycolic acid-containing glycolipid, i.e., glucose mycolate, trehalose dimycolate, and trehalose monomycolate. The carbon chain length of their mycolic acids is shorter (C36-48) than that in mycobacteria (longer than C70), and the glycolipid consists of only alpha-mycolic acid. One intravenous administration of 500 micrograms of each purified glycolipid to ICR mice in the form of water-in-oil-in-water emulsion without any protein antigens caused prominent granuloma formation in the lungs, spleen, and liver. The lung index in the treated mice was about 3.5 times larger than that in the control mice (given water-in-oil-in-water emulsion only) at 1 week after the injection and then rapidly declined, while spleen and liver indices peaked at 2 weeks after the injection and persisted longer. The granuloma consisted of macrophages, some of which phagocytized glycolipid micelles, lymphocytes, monocytes, and neutrophils. In addition, many small hemopoietic islands were observed in the liver sinusoids, where various immature blood cells were trapped by the prominent cytoplasmic projections of Kupffer cells. The granuloma formation and hemopoiesis observed here are considered to be the most characteristic morphological expression of macrophage activation in these organs. This is the first report to show that such histological changes can be induced by chemically defined and homogeneous mycolic acid-containing glycolipids other than those of mycobacteria.  相似文献   
87.
Six solitary gastric polyps in the acid-secreting fundic mucosa were histo-chemically investigated using the mucin histochemistry, immunoperoxidase method, and silver methods for endocrine cells. Histologically, the polyps were grouped into three types : they largely consisted of either hyperplastic foveolar cells (group 1), normal-appearing fundic gland cells with mild cystic changes (group 2) or hyperplastic fundic gland cells with cystic dilatation (group 3). The presence of parietal cells and mucous neck cells was confirmed in all polyps by the immunoperoxidase method using parietal cell autoantibody and the paradoxical Concanavalin A staining, respectively. Regarding the endocrine component, somatostatin-containing cells, Grimelius-positive argyrophil cells, and Fontana-Masson-positive enterochromaffin cells were scattered in the fundic gland area of the polyps as well as in the surrounding normal-appearing fundic mucosa. Gastrin-containing cells were absent. In one of the group 2 polyps and both group 3 polyps, a varying number of glicentin-containing cells were found among the fundic gland components : In one polyp in group 3, glucagon immunoreactivity was detected in the glicentin-containing cells. These findings suggest that some of the polyps express characteristics of the fetal fundic mucosa, since glicentin and glucagon immunoreactivities in normal human stomach have been detected exclusively in the fetal fundus. ACTA PATHOL. JPN. 35: 831–840, 1985.  相似文献   
88.
Some patients with bronchial asthma have increased cough sensitivity. In such patients coughing may be an inducer of wheeze. The aim of the present study was to investigate the effect of Bakumondo-to on the cough sensitivity and respiratory tract inflammation in asthmatic patients with increased cough sensitivity. In addition influences of intensity of respiratory tract inflammation, gender, type of asthma, and disease period on the effect of Bakumondo-to on the cough sensitivity were examined. Twenty-one bronchial asthmatics whose cough thresholds to capsaicin were less than 3.9 microM were examined. METHODS: Cough thresholds to capsaicin (concentration of inhaled capsaicin solution causing 5 or more coughs) was measured before and after 2 months or more treatment with Bakumondo-to (9 g/day, TJ-29). Number of eosinophils in peripheral blood, sputum eosinophil ratio, and ECP level in the serum were also measured before and after treatment. RESULTS: Bakumondo-to significantly increased the cough threshold. Although respiratory tract inflammation was not significantly improved, number of eosinophils in peripheral blood, sputum eosinophil ratio and ECP level in the serum were remarkably decreased more than the half. And Bakumondo-to was more effective in asthmatic subjects with severe airway inflammation. Furthermore, a greater effect of it was observed in women. A greater effect was also observed in patients having a disease duration of less than 1 year. CONCLUSION: Our results suggest that Bakumondo-to may be an effective therapeutic preparation for coughing in asthmatic patients with cough hypersensitivity.  相似文献   
89.
The precise distribution and expression of Toll-like receptor (TLR) 9 in gut-associated lymphoid tissues (GALTs) has not been elucidated. In this study, we investigated the expression pattern of TLR9 in adult and neonatal swine GALTs by real-time quantitative PCR, western blot, confocal laser microscopy and flow cytometric analysis. The swine TLR9 gene was preferentially expressed in adult Peyer's patches (Pps) and mesenteric lymph nodes (MLNs), which contained approximately three times higher TLR9 than the spleen. Other tissues exhibited only weak expression of TLR9. In neonatal swine, elevated expression of TLR9 was detected only in MLNs. We firstly showed that highly expressive (TLR9(+)) cells were formed in Pps and MLNs. In addition, TLR9(+) cells were present not only in immune cells such as dendritic cells and B cells but also in follicle-associated epithelia (FAE) including membranous cells (M cells) in Pps. These results suggest that Pps and MLNs provide the host defense with the ability to respond to a variety of bioactive oligonucleotides (ODNs) from bacteria at a conductive site of initial immune responses.  相似文献   
90.
BACKGROUND: Angiographic regression of luminal narrowing occurs 6 months to 3 years poststenting. However, after 4 years lesions progressed gradually and late restenosis was observed in 28% of 179 Palmaz-Schatz-stented lesions during the past 10 years. Elucidating its pathogenesis is pivotal to developing preventive strategies. METHODS AND RESULTS: Histopathological and immunohistochemical studies were performed in 19 stented coronary arteries obtained from 19 patients autopsied after noncardiac death 2-7 years poststenting. The quality/severity of chronic inflammatory cells (T lymphocytes, macrophages and multinucleated giant cells) infiltration around the stent struts that is observed even in the absence of restenosis depended on the time elapsed from stenting: a) 2 years postprocedure, in spite of angiographic regression during the first year and pathologically expressed as maturation of the neointimal scar, there was chronic inflammatory response evidence: neovascularization and lymphocyte infiltration, b) > or = 3 years: the neointimal smooth muscle cells were sparse with abundant proliferation of collagen fibers. Presence of slight helper/inducer T lymphocytes and mild macrophage infiltration around the stent struts was evident immunohistochemically, c) > or = 4 years: prominent infiltration by lipid-laden macrophages with strong collagen-degrading matrix metalloproteinase immunoreactivity was observed around the struts. In two of these arteries, the surface contacting the stent was focally disrupted and covered by nonocclusive mural thrombi. CONCLUSIONS: Stainless steel stents evoke a remarkable foreign-body inflammatory reaction to the metal. These persistent peri-strut chronic inflammatory cells may accelerate new indolent atherosclerotic changes and consequent plaque vulnerability.  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