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   13381篇
  免费   842篇
  国内免费   237篇
耳鼻咽喉   745篇
儿科学   149篇
妇产科学   102篇
基础医学   2428篇
口腔科学   1985篇
临床医学   958篇
内科学   1000篇
皮肤病学   246篇
神经病学   558篇
特种医学   647篇
外国民族医学   4篇
外科学   1338篇
综合类   1531篇
现状与发展   1篇
预防医学   240篇
眼科学   697篇
药学   671篇
  8篇
中国医学   284篇
肿瘤学   868篇
  2024年   27篇
  2023年   149篇
  2022年   340篇
  2021年   414篇
  2020年   382篇
  2019年   360篇
  2018年   393篇
  2017年   364篇
  2016年   368篇
  2015年   407篇
  2014年   667篇
  2013年   687篇
  2012年   654篇
  2011年   653篇
  2010年   657篇
  2009年   597篇
  2008年   593篇
  2007年   574篇
  2006年   544篇
  2005年   481篇
  2004年   437篇
  2003年   406篇
  2002年   350篇
  2001年   341篇
  2000年   287篇
  1999年   291篇
  1998年   255篇
  1997年   272篇
  1996年   248篇
  1995年   197篇
  1994年   195篇
  1993年   186篇
  1992年   160篇
  1991年   178篇
  1990年   143篇
  1989年   151篇
  1988年   115篇
  1987年   94篇
  1986年   98篇
  1985年   97篇
  1984年   113篇
  1983年   48篇
  1982年   83篇
  1981年   82篇
  1980年   79篇
  1979年   53篇
  1978年   47篇
  1977年   35篇
  1976年   36篇
  1975年   25篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
A pituitary tumour composed of well-differentiated corticotrophs and adrenocortical cells is reported. Sections of the tumour revealed a mixture of small round cells with amphophilic or basophilic periodic acid-Schiff (PAS)-positive cytoplasm and large spherical and oval cells with abundant, granular, partly vacuolated PAS-negative cytoplasm. The small cells contained type 1 cytokeratin-positive microfilaments, numerous 250–500 nm endocrine-type secretory granules immunoreactive for adenocorticotropic hormone (ACTH) and -lipotropin. The large cells possessed ample cytoplasm filled with abundant vesicular smooth endoplasmic reticulum, numerous mitochondria possessing tubulovesicular cristae and frequent dense bodies. They lacked the features of pituitary endocrine cells or folliculostellate cells and were found to contain a panel of steroidogenic dehydrogenases and hydroxylases. The tumour was classified as a choristoma, in which two distinct cells types, corticotrophs and adrenocortical cells, were mixed. We suggest that, under continued ACTH stimulation, uncommitted stem cells may differentiate into adrenocortical cells. Alternatively, the presence of adrenocortical cells may be the result of heterotopia.  相似文献   
52.
将类霍乱毒素B原结合的辣根过氧化物酶(CB-HRP)注入大鼠一侧颌、舌下腺,标记了脑干内支配该腺副交感节前神经元的胞体及其轴、树突。在光学显微镜下,对所标神经元的位置、胞体形态、大小、树突的分布以及轴突在脑干内的行程做了较为系统的观察和测量,并结合有关参数的相关分析,对泌涎神经元的某些生理学特性做了初步探讨。  相似文献   
53.
Intending to clarify the true Incidence of Invasive lobular carcinoma of the breast In Japanese women as well as the frequency of unilateral multlcentriclty, 362 cases of clinically defined monocentrlc breast cancer without pre-operative biopsy (previously fine needle aspiration or needle biopsy were routinely carried out for every case) were examined by whole mammary gland serial sectioning. On the basis of pathology and the World Health Organization classification of breast tumors, each case was assigned to one of two main histologlc types: Invasive lobular carcinoma (ILC) or Invasive ductal carcinoma (IDC). Invasive lobular carcinoma was further separated into classic and variant types by employing previously published criteria. Twenty-one cases of ILC (5.8%) were diagnosed, which Is more than In most previous Japanese studies. Unilateral multicentric breast carcinoma was detected In 9.5% of ILC and 16.1% of IDC (the difference was found not significant). Microscopically, ILC tumors were found to be, on average, larger than IDC. Patients with classic type ILC tended to be younger than those with variant type or IDC. Estrogen receptor expression was found more frequently In variant type ILC than in classic type. These results suggest that the incidence of invasive lobular carcinoma of the breast In Japanese women is low and that unilateral multicentricity Is not significantly higher in ILC than in IDC.  相似文献   
54.
Summary Intracellular fibrillar congophilic inclusions are well known as neurofibrillary tangles in neurons and as Biondi bodies in choroid plexus epithelial cells. Recently similar amyloid-like inclusions in adrenal cortical cells were described (Eriksson and Westermark 1990). This study on 150 adrenal glands confirms these observations. In our material the age-related accumulation of congophilic inclusions starts earlier (in the sixth decade) and reaches a higher incidence (42.7%). We found similar intracellular inclusions in other endocrine organs, for example in the anterior lobe of the pituitary, in the cells of parathyroid glands and in Sertoli cells. The age-related incidence of these fibrillar inclusions in the pituitary was 68%; the co-incidence with interstitial amyloid deposits was 49.5%. Thus the intracellular accumulation of congophilic fibrils in old age is a widespread phenomenon and occurs not only in neurons but also in endocrine cells (adrenal, pituitary and parathyroid glands) and in active secretory cells (choroid plexus and Sertoli cells).  相似文献   
55.
Dermatoglyphic investigation of palm prints in patients with Incontinentia pigmenti revealed in five of eight cases a partial ridge dissociation with lack of sweat gland pores. This disease can, therefore, be accepted as a second X-linked anhidrotic ectodermal dysplasia, which, however, is only segregated in the female.  相似文献   
56.
调查了90具童尸用状腺的基本形态,可分四型。其中以甲状腺由两侧叶及峡部组成者为最多,占50.22%。测量了甲状腺各部的长、宽、厚。分年龄组进行了数据的统计学处理,并计算出儿童与成人甲状腺各部相应值的百分比。结果显示:小儿甲状腺侧叶的长度和宽度在幼儿期(1—3岁)就已发育近成人的一半。随着年龄的增长,甲状腺各部的均值逐渐增加。除各部的宽度以及锥体叶的长度外,各相邻两组间同项均数的比较,经双侧T检验发现差异具有高度显著性(P<0.01)。  相似文献   
57.
Mammary gland adenomyoepitheliomas are benign complex mammary gland tumors composed of neoplastic cells of epithelial and myoepithelial origins, described in many species (humans, dogs, cats, rats) and rarely in mice. We report here an adenomyoepithelioma in a C57BL/6 female mouse. Histologically, tubes and cords formed by neoplastic epithelial cells were separated by bundles of neoplastic myoepithelial cells in a clear and partially mucinous matrix. The tumor displayed characteristics of a benign neoplastic proliferation with a compressive growth pattern, and moderate cellular pleomorphism and mitotic index. At immunohistochemistry, the epithelial cells were strongly cytokeratin positive; the myoepithelial cells were weakly cytokeratin positive and strongly smooth muscle actin positive. This is to our knowledge, the first report of a mammary gland adenomyoepithelioma in a C57BL/6 mouse.  相似文献   
58.
涎腺癌肉瘤临床及病理分析   总被引:6,自引:0,他引:6  
目的:探讨涎腺癌肉瘤的临床病理学特点及其鉴别诊断。方法:对3例涎腺癌肉瘤患者的临床资料进行回顾性研究并复习相关文献,对全部病例的组织学标本重新进行镜下观察。结果:涎腺癌肉瘤临床表现常为迅速增大的颜面部肿物并伴疼豢。光匀下组织学观察常可见肉瘤和癌两种成分并存,癌多为鳞状细胞癌和腺癌,肉瘤以骨或软骨肉瘤为主。结论:涎腺癌肉瘤的临床特点与涎腺其他恶性肿瘤较难区别,但涎腺癌肉瘤的恶性程度极高。  相似文献   
59.
Fms-like tyrosine kinase 1 (Flt-1) performs a subordinate effector role in mesenchymal angiogenesis and potentially serves an equally important functional role as a self-contained receptor in epithelial cells. In both endothelial cells and epithelial cells, Flt-1/vascular endothelial growth factor receptor 1 (VEGFR1) downstream signalling is involved in regulating cellular processes such as cytoskeletal changes and cellular survival protection. Cellular renewal of the gastrointestinal mucosa is based on these processes and might involve Flt-1/VEGFR1 pathway activities; the molecular mechanisms regulating these cellular dynamics remain unclear. This study was performed to investigate the presence and distribution of Flt-1/VEGFR1 in epithelial cells of the gastrointestinal tract by immunohistochemistry (IHC). Gastrointestinal tissues were taken from eight anatomical sites from mouse, rat, dog, swine and monkey. Present results revealed a cytosolic Flt-1/VEGFR1 staining pattern in mucosal epithelial cells for all investigated species. Non-epithelial structures also displayed a distinct Flt-1/VEGFR1 positivity and included vascular smooth muscle walls, enteric smooth muscle layers, the enteric nervous system and capillary endothelial cells. Diverse intensities of the Flt-1/VEGFR1 binding reaction within each species were observed in the intestinal mucosa with a strong immunoreaction in enterocytes and with a low protein expression in the ileum in most species. Crypt cells in the large intestine were mostly negative for Flt-1/VEGFR1. A peculiar and mainly intranuclear antibody binding reaction was found in Brunner's gland epithelial cells of mouse and rat whereas Brunner's glands of dog, swine and monkey remained completely negative. These results indicate a potential involvement of Flt-1/VEGFR1 in normal restitution of gastrointestinal structures in the species studied. Additionally, intranuclear Flt-1/VEGFR1 antibody binding in Brunner's glands of rodents may suggest a nuclear translocation of the transmembrane VEGFR1 which has not previously been described.  相似文献   
60.
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