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   3201篇
  免费   149篇
  国内免费   17篇
耳鼻咽喉   78篇
儿科学   30篇
妇产科学   28篇
基础医学   415篇
口腔科学   47篇
临床医学   185篇
内科学   898篇
皮肤病学   39篇
神经病学   223篇
特种医学   84篇
外科学   517篇
综合类   10篇
预防医学   118篇
眼科学   27篇
药学   156篇
中国医学   2篇
肿瘤学   510篇
  2023年   18篇
  2022年   36篇
  2021年   67篇
  2020年   42篇
  2019年   27篇
  2018年   47篇
  2017年   40篇
  2016年   66篇
  2015年   49篇
  2014年   51篇
  2013年   71篇
  2012年   140篇
  2011年   154篇
  2010年   84篇
  2009年   69篇
  2008年   146篇
  2007年   142篇
  2006年   163篇
  2005年   157篇
  2004年   149篇
  2003年   126篇
  2002年   87篇
  2001年   116篇
  2000年   101篇
  1999年   89篇
  1998年   49篇
  1997年   26篇
  1996年   24篇
  1995年   18篇
  1993年   17篇
  1992年   67篇
  1991年   70篇
  1990年   68篇
  1989年   65篇
  1988年   70篇
  1987年   68篇
  1986年   71篇
  1985年   83篇
  1984年   48篇
  1983年   38篇
  1982年   19篇
  1979年   24篇
  1978年   19篇
  1977年   22篇
  1975年   19篇
  1973年   19篇
  1971年   17篇
  1969年   24篇
  1968年   34篇
  1967年   20篇
排序方式: 共有3367条查询结果,搜索用时 0 毫秒
31.
Lymphoid cell lines were established from five different species of monkeys which were positive in antibodies cross-reactive with human T-cell leukemia virus type I (HTLV-I) and were shown to contain provirus sequences homologous to HTLV-I. Gene-specific probes of HTLV-I, gag, pol, env, pX, and LTR, hybridized efficiently with monkey DNAs from these cell lines under stringent conditions, indicating that the proviruses are very similar to HTLV-I along with whole viral genomes. However, the preliminary restriction mapping turned out the difference between simian retroviruses and HTLV-I and also among simian retroviruses. These findings suggest a common ancestor of simian and human retroviruses, but exclude the recent interspecies transmission between monkeys and humans.  相似文献   
32.
Summary Vincristine-induced crystalloid inclusions were examined in the neurons and neuronal processes of young rats by the electron microscope (EM) equipped with a tilting stage. Using a computer system that reproduces three-dimensional organization, an optical transformation method was applied to the microtubules and neurofilaments in an attempt to clarify the morphological appearance and internal pattern of crystalloid inclusions. The dimensional models obtained were compared with actual EM photographs, and the characteristic ultrastructural component and morphology were drawn out.Basically, a crystalloid inclusion is composed of four strands of intermediate 10 nm neurofilaments connected to one another by four side-arms producing a circular profile on a transverse section. These four side-arms seemed to arise from nodules within the filaments at regular intervals simulating a bead-like appearance. These data did not significantly differ from those obtained from EM images. Characteristically, these crystalloid inclusions began to appear 6 h after the administration of 10–3 M vincristine sulfate and persisted up to a period of 6 days. Beyond that, however, these inclusions were no longer demonstrable suggesting a transient state. This was in contrast to neurofibrillary tangles which appeared to be permanent changes.  相似文献   
33.
Clinical and Experimental Nephrology - The progression of chronic kidney disease (CKD) depends on the extent of fibrosis in the kidneys; however, a renal biopsy is necessary to evaluate the...  相似文献   
34.
An animal model of HTLV-I associated uveitis was created. One rabbit developed bilateral uveitis 3,5 years after being injected with blood from an HTLV-I-infected rabbit. The proviral DNA of HTLV-I was detected by polymerase chain reaction and dot-blot hybridization in the aqueous humor of the anterior chamber and the vitreous body. Histopathological examination revealed marked corneal opacity with neovascularization and infiltration of inflammatory cells, mainly plasma cells, into the iris, ciliary body, and choroid. Complicated cataracts were also seen. The retinas were destroyed and replaced by gliosis. This is the first animal model of HTLV-I-associated disease to be reported.  相似文献   
35.
36.
Activated microglial cells and peripheral macrophages are hardly distinguishable from the viewpoints of morphology and function. There are various immunological markers common to both microglial cells and peripheral macrophages. In the present study, however, we found that microglial cells have distinct characters in terms of adhesion and morphology. By using a "rheoscope," that is an apparatus to rheologically measure the strength of cell adhesion to substrates, rat microglial cells were found to attach to polystyrene dishes much more weakly than alveolar and peritoneal macrophages. Interferon-gamma (IFNgamma) strengthened the adhesion of alveolar and peritoneal macrophages, whereas it weakened that of microglial cells. Morphological changes of microglial cells induced by IFNgamma were also different from those of peripheral macrophages. Furthermore, alveolar and peritoneal macrophages produced NO in response to IFNgamma, while microglial cells did not. When cultured on astrocyte-derived extracellular matrix (AsECM) in serum-free medium, only microglial cells extended multiple ramified processes. Conversely, alveolar and peritoneal macrophages on AsECM shrunk their ruffling membrane and rounded up. These distinctions between microglial cells and macrophages may reflect differences in cell lineages as well as environments in which individual cells reside.  相似文献   
37.
An Epstein-Barr virus (EBV)-negative lymphoma line (JBL) was established in vitro from pleural effusion of an EBV-seropositive 29-year-old Japanese female with Burkitt's lymphoma. JBL cells as well as her original lymphoma cells bore monoclonal surface IgM with lambda light chains. The JBL line grew in single cell suspension with a doubling time of 30 hours. Attempts were made to serially transplant JBL cells in antilymphocyte serum-treated newborn hamsters; intraperitoneal implantation of 1-3 X 10(7) cells gave rise to invasive tumors in all recipients with death after 10 to 14 days. The hamster-passage line, now in the 9th passage, has been converted to an ascitic form with progression to leukemia in some animals. A "starry sky" pattern closely resembling the human tumor material was preserved in every tumor through serial animal passage.  相似文献   
38.
The authors report a patient carrying a missense mutation in exon 10 of tau that causes a substitution at codon 301 (P301S). Although the patient shares the rapidly progressive frontotemporal dementia of the other reported pedigrees with P301S, the clinical phenotype is unique in that parkinsonism was a major symptom in the early stage and because behavioral symptoms with dementia became prominent 2 years after the onset of the disease. This study substantiates the notion that tau mutations at codon 301 can show various phenotypes.  相似文献   
39.
The Brucella abortus ribosomal protein L7/L12 is an immunodominant antigen and an interesting candidate for the development of oral live vaccines against brucellosis. Here, a recombinant Lactococcus lactis strain producing L7/L12 under the control of nisin inducible promoter was orally administered to BALB/c mice. Significant levels of anti-L7/L12 specific IgA detected in feces revealed an induced local humoral immune response. However, serum analysis did not reveal any anti-L7/L12 antibodies suggesting the absence of a systemic response. Nevertheless, the vaccinated mice showed a partial protective immunity against B. abortus virulent strain (S2308) challenged by intraperitoneal inoculation.  相似文献   
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