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   7908篇
  免费   492篇
  国内免费   45篇
耳鼻咽喉   75篇
儿科学   160篇
妇产科学   46篇
基础医学   1090篇
口腔科学   317篇
临床医学   451篇
内科学   2014篇
皮肤病学   177篇
神经病学   656篇
特种医学   294篇
外科学   1558篇
综合类   29篇
预防医学   169篇
眼科学   150篇
药学   370篇
中国医学   8篇
肿瘤学   881篇
  2023年   44篇
  2022年   91篇
  2021年   176篇
  2020年   91篇
  2019年   114篇
  2018年   177篇
  2017年   147篇
  2016年   178篇
  2015年   165篇
  2014年   219篇
  2013年   252篇
  2012年   369篇
  2011年   433篇
  2010年   270篇
  2009年   233篇
  2008年   379篇
  2007年   391篇
  2006年   378篇
  2005年   387篇
  2004年   388篇
  2003年   364篇
  2002年   370篇
  2001年   259篇
  2000年   252篇
  1999年   219篇
  1998年   100篇
  1997年   58篇
  1996年   63篇
  1995年   64篇
  1994年   53篇
  1993年   52篇
  1992年   136篇
  1991年   122篇
  1990年   122篇
  1989年   129篇
  1988年   100篇
  1987年   108篇
  1986年   99篇
  1985年   91篇
  1984年   86篇
  1983年   71篇
  1982年   35篇
  1979年   73篇
  1978年   42篇
  1977年   34篇
  1973年   40篇
  1970年   36篇
  1969年   39篇
  1968年   38篇
  1967年   42篇
排序方式: 共有8445条查询结果,搜索用时 15 毫秒
51.
To the significance of basophilia in haematopoietic disorders, six draw attention to cases have been analyzed. Associated diseases included acute myelogenous leukaemia (AML-M2, M3, M4, and M6), refractory anaemia with excess of blasts (RAEB) and RAEB in transformation (RAEB-T). Two AML cases (M2, M6) were preceeded by myelodysplastic syndromes (MDS). All patients showed greater than 3% basophilia in peripheral blood and bone marrow. Basophils were identified successfully by metachromatic staining with toluidine blue in all cases. Three patients (M3, M4, RAEB) presented with lymphadenopathy, suggesting an association with extramedullary involvement. Neutrophil alkaline phosphatase (NAP) activity was significantly reduced in four patients with AML (M2, M3, M4) and RAEB-T. The clinical course was generally unfavourable characterized by short remission duration or disease progression except for the patient with RAEB. Haemorrhage was the main cause of death rather than infection. Cytogenetic analysis revealed unique abnormalities involving chromosomes 3q21, 5q31, and 17q11 where the genes for some haematopoietic growth factors or their receptors are located, in addition to t(6;9) and t(15;17).  相似文献   
52.
A case of DOC-secreting adrenocortical carcinoma in a 66-year-old man is reported. He had hypertension, hypokalemia, suppressed PRA, and excessive serum levels of DOC. His serum aldosterone level was normal. The resected adrenal mass weighed 230 g. Histologically, the tumor was mainly composed of compact cells associated with necrosis and atypical mitoses. Invasion of venous structure, sinusoids, and capsule was also present. Immunohistochemically, P450 C21 (21 -hydroxylase) was positive in many tumor cells, and P450 C17(17 α-hydroxylase) was intensely positive in a relatively small number of tumor cells. The patient died 9 months after operation due to rupture of metastatic liver tumor.Endocr Pathol 4:165–168, 1993.  相似文献   
53.
The applicability of a recently developed non-radioactive DNA labelling and detection method, which uses the digoxigenin (DIG) enzyme linked immunosorbent assay (ELISA) system, for the detection of viral infections in pathology specimens by in situ hybridisation, was examined. Its efficacy was compared with that of biotin and radioisotope labelling methods. Three cases of progressive multifocal leucoencephalopathy, two of verruca vulgaris, and seven cases of laryngeal papilloma were studied. The sensitivity of the DIG labelled probe was almost the same as that of a 35S-labelled probe in the dot-blot hybridisation test. Using in situ hybridisation with 35S-labelled and DIG labelled probes, the levels of the hybridised signals detected were similar. The biotin labelled probe was less sensitive, particularly in the cases of laryngeal papilloma. The DIG labelling and detection method was highly sensitive and applicable to the detection of viral infection by ISH, and is preferable to a radiolabelled probe, especially when in situ hybridisation is done in the pathology laboratory.  相似文献   
54.
We investigated the fine structure and mineral components of 29 stonelike masses obtained from the mesenteries of four adult cadavers, using optical microscopy, backscattered electron imaging, scanning electron microscopy, energy-dispersive X-ray microanalysis, and X-ray diffraction. Although the overall appearance of the stonelike masses measuring about 5–20mm in diameter and 0.06–3.1g in dry weight was roughly grouped into smooth bulb- and uneven bulk-shaped types, all the calcified masses basically consisted of core and mantle regions. The smooth bulb-shaped masses had a broad mantle with many concentric rings, whereas the uneven bulk-shaped masses contained a large core. In their core regions, spherulitic and short bundle-shaped deposits composed of needle-shaped apatite crystals were mainly found among loose collagen fibers. Their mantle regions, on the other hand, showed the concentric structures of dense collagen fibers in the intra- and/or extrafibrous calcification with fine sandy grain-shaped deposits. The mineral elements were mainly Ca and P, and the major crystals were hydroxyapatite. Hexahedral whitlockite containing Mg was a minor component. The fiber-rich mantle regions showed lower calcification and lesser crystallization than the fiber-poor core region. When necrotic or some tumor adipose tissues and necrotic lymphoid tissues that might have been caused by some digestive diseases are recognized as foreign matter, their tissues occasionally will be calcified and grow into stonelike masses. These stonelike masses tend to occur more often in women than in men.  相似文献   
55.
56.
A case of recurrent soft part sarcoma with focal areas showing epithelial differentiation in the right thigh in a 78-year-old woman is reported. The primary tumor consisted of myxoid areas and solid areas, in which relatively uniform epithelioid tumor cells were arranged in sheets, whereas pleomor-phism and a storiform pattern appeared in the recurrent tumors. Thus this tumor was suspected to be a malignant fibrous histiocytoma. However, further studies showed unexpected ultrastructural and immunohistochemical features. Cytokeratin immu-noreactivity and tonofilamentlike structures probably indicated epithelial differentiation of some tumor cells. From the clinical and histological findings, this tumor should be identified as a malignant fibrous histiocytoma with phenotypic expressions of epithelial cell.  相似文献   
57.
A case of spindle cell carcinoma of the uterus in a 56-year-old woman is reported. Microscopically, it showed an intimate admixture of epithelial and sarcomatous elements. The epithelial nature, especially the squamous cell nature, in sarcomatous areas was indicated by immunoreactivity for keratin and ultrastructural characters, such as bundles of tonofilaments and some cell junctions, while the tumor cells in these areas were also vimentin-positive. Furthermore, ultrastructural study and immunostaining for actin demonstrated myofilaments in tumor cells in both tumor nests and sarcomatous areas. This may impart the high degree of invasiveness of spindle cell carcinoma.  相似文献   
58.
Summary In a series of 79 cases of primary esophageal carcinoma resected at The Center for Adult Diseases, Osaka, there were six tumors with specific histopathologic features valid for the diagnosis of argyrophil cell carcinoma. Of the 6 tumors, 3 were studied electron microscopically and assay for ACTH content was performed on 4 tumors.Clinically, the ages of the 6 patients ranged from 56 to 71 years; two were women and four men. Four of the 6 patients died with widespread tumor recurrences within 9 months of operation.Microscopically, the 6 tumors were composed largely or almost entirely of small, spindle-shaped cells resembling those of oat cell carcinoma of the lung, and were characterized by the arrangement of tumor cells in solid sheets or anastomosing cords, the presence of argyrophil tumor cells, and the deposits of amyloid. Electron microscopically, the three tumors contained neurosecretory-type granules. Using bioassay or radioimmunoassay ACTH activity in the tumor tissues was detected in 3 out of the 4 tumors determined.From the light and electron microscopic characteristics and the assay evidence, it seems reasonable to conclude that the 6 tumors are endocrine polypeptide producing tumors (apudomas) that arise from argyrophil cells normally found among the basal cells of the esophageal mucosa, and that they represent a distinct histopathologic entity clearly distinguishable from other types of esophageal carcinomas.Supported in part by a Grant-in Aid for Cancer Research from the Ministry of Education, Science and Culture, and the Ministry of Health and Welfare, JapanThe authors are grateful to Prof. H. Imura and Dr. Y. Hirate, Department of Internal Medicine, Kobe University School of Medicine for their interest and performing the assays for ACTH on the tumor tissues.  相似文献   
59.
Several Caucasian studies and one Japanese study have observed associations between human leukocyte antigen (HLA) class I specificities, including A24 (9) and A26 (10) and schizophrenia. Most of those studies were conducted in 1970s and early 1980s, when the typing technique of HLA was not adequately reliable. Also, an operational diagnostic system was not employed in many of the studies. The present study investigated frequencies of HLA-A specificities in schizophrenia patients (ICD-10 and DSM-III-R, n=98) and sex-matched healthy controls (n=392) from population in the southwestern part of Japan. HLA-B and -C specificities were studied in addition. Frequencies of subjects possessing A24 and A26 were not different between the patients and controls (54% and 24% in the patients and 62% and 24% in the controls, respectively). No significant difference was found in frequencies of other class I (A, B, and C) specificities between the patients and the controls. Thus, the present study provided no evidence for an association between the HLA class I specificities, including A24, A26, and others, and schizophrenia in the Japanese population.  相似文献   
60.
Hepatocellular carcinomas (HCCs) were induced in male Fischer 344 rats with dietary 3'-methyl-4-(dimethylamino)-azobenzene treatment and were classified into solid, glandular (well- or poorly differentiated), and trabecular types. Investigation of cell proliferation kinetics and immunohistochemical localization of transforming growth factor alpha (TGF-alpha) demonstrated all solid (n = 24) and poorly differentiated glandular type (n = 6) HCCs to have TGF-alpha-positive nuclei. Nuclear staining of TGF-alpha was also observed in 13 of 28 (46%) trabecular-type HCCs, whereas 12 (43%) exhibited cytoplasmic staining, and 3 (11%) were negative. As for well-differentiated glandular HCCs, 7 of 20 (35%) were positively stained in their nucleus, another 7 (35%) demonstrated antibody binding in the cytoplasm, and 6 (30%) were negative. The order for growth rate evaluated by bromodeoxyuridine (BrdU) labeling was solid (38.22%), poorly differentiated glandular (26.82%), trabecular (7.98%), and well-differentiated glandular (2.57%) types. For trabecular HCCs with nuclear, cytoplasmic, or negative TGF reactions, values were 13.39% (n = 13), 3.61% (n = 12), and 2.01% (n = 3), respectively. Likewise, BrdU-labeling indices for the counterpart groups of well-differentiated glandular type HCCs were 4.53, 1.91, and 1.29%, respectively. The results indicate that TGF-alpha expression might be linked to histopathological differentiation and cell proliferation in rat HCCs.  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