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   168篇
  免费   43篇
  2021年   4篇
  2020年   1篇
  2019年   1篇
  2018年   5篇
  2017年   1篇
  2016年   4篇
  2015年   12篇
  2014年   10篇
  2013年   11篇
  2012年   10篇
  2011年   3篇
  2010年   4篇
  2009年   3篇
  2008年   7篇
  2007年   15篇
  2006年   6篇
  2005年   8篇
  2004年   4篇
  2003年   6篇
  2002年   13篇
  2001年   7篇
  2000年   7篇
  1999年   8篇
  1998年   9篇
  1997年   6篇
  1996年   3篇
  1995年   7篇
  1994年   6篇
  1993年   5篇
  1992年   2篇
  1991年   1篇
  1990年   2篇
  1989年   1篇
  1988年   2篇
  1987年   3篇
  1986年   1篇
  1985年   2篇
  1984年   2篇
  1982年   1篇
  1981年   3篇
  1980年   2篇
  1977年   2篇
  1972年   1篇
排序方式: 共有211条查询结果,搜索用时 157 毫秒
201.
Cuprizone, copper chelator, treatment of mouse is a toxic model of multiple sclerosis (MS) in which oligodendrocyte death, demyelination and remyelination can be observed. Understanding T and B cell subset as well as their cytokines involved in MS pathogenesis still requires further scrutiny to better understand immune component of MS. The study presented here, aimed to evaluate relevant cytokines, lymphocytes, and gene expressions profiles during demyelination and remyelination in the cuprizone mouse model of MS. Eighty male C57BL/6J mice fed with 0.2% cuprizone for eight weeks. Cuprizone has been removed from the diet in the following eight weeks. Cuprizone treated and control mice sacrificed biweekly, and corpus callosum of the brain was investigated by staining. Lymphocyte cells of mice analyzed by flow cytometry with CD3e, CD11b, CD19, CD80, CD86, CD4, CD25 and FOXP3 antibodies. IFN-gamma, IL-1alpha, IL-2, IL-5, IL-6, IL-10, IL-17, TNF-alpha cytokines were analyzed in plasma samples. Neuregulin 1 (Nrg1), ciliary neurotrophic factor (Cntf) and C-X-C chemokine receptor type 4 (Cxcr4) gene expressions in corpus callosum sections of the mice brain were quantified. Histochemistry analysis showed that demyelination began at the fourth week of cuprizone administration and total demyelination occurred at the twelfth week in chronic model. Remyelination occurred at the fourth week of following withdrawal of cuprizone from diet. The level of mature and activated T cells, regulatory T cells, T helper cells and mature B cells increased during demyelination and decreased when cuprizone removed from diet. Further, both type 1 and type 2 cytokines together with the proinflammatory cytokines increased. The level of oligodendrocyte maturation and survival genes showed differential gene expression in parallel to that of demyelination and remyelination. In conclusion, for the first-time, involvement of both cellular immune response and antibody response as well as oligodendrocyte maturation and survival factors having role in demyelination and remyelination of cuprizone mouse model of MS have been shown.  相似文献   
202.
203.
204.
Diethard Sanders  Karl Krainer 《Facies》2005,51(1-4):522-540
During the Early Permian, in the area of the Carnic Alps, a quartz-gravelly beach fringed a mixed siliciclastic-carbonate lagoon with fleshy algal meadows and oncoids; seaward, an ooid shoal belt graded down dip to a low-energy carbonate inner shelf with phylloid algal meadows. In limestones, foraminiferal biomurae and bioclast preservation record tapholoss by rotting of non-calcified organisms (interpreted as fleshy algae) and by dissolution of aragonitic fossils. Carbonate loss by dissolution was counteracted and, locally, perhaps exceeded by carbonate precipitation of encrusting foraminifera and as oncoids. Sites of abrasion and carbonate dissolution (beach), sites with tapholoss by rotting and dissolution, but with microbialite/foraminiferal carbonate precipitation (lagoon, inner shelf), and sites only of carbonate precipitation (ooid shoals) co-existed on discrete shelf compartments. Compartmentalized, contemporaneous carbonate dissolution and precipitation, to total amounts yet difficult to quantify, impede straightforward estimates of ancient carbonate sediment budget.  相似文献   
205.
Dr. Karl Krainer 《Facies》1995,33(1):195-214
Summary A heretofore undocumented example of skeletal mounds formed by the dasycladacean algaAnthracoporella spectabilis is described from mixed carbonate-clastic cycles (Auernig cyclothems) of the Late Carboniferous (Gzhelian) Auernig Group of the central Carnic Alps in southern Austria. The massive mound facies forms biostromal reef mounds that are up to several m thick and extend laterally over more than 100 m. The mound facies is developed in the middle of bedded limestones, which are up to 16 m thick. These limestones formed during relative sea-level highstands when clastic influx was near zero. The mound facies is characterized by well developed baffler and binder guilds and does not show any horizontal or vertical zonation. Within the massive mound faciesAnthracoporella is frequently found in growth position forming bafflestones and wackestones composed of abundantAnthracoporella skeletons which toppled in situ or drifted slightly.Anthracoporella grew in such profusion that it dominated the available sea bottom living space, forming ‘algal meadows’ which acted as efficient sediment producers and bafflers. BecauseAnthracoporella could not provide a substantial reef framework, and could not withstand high water turbulence, the biostromal skeletal mounds accumulated in shallow, quiet water below the active wave base in water depths less than 30 m. The massive mound facies is under- and overlain by, and laterally grades into bedded, fossiliferous limestones of the intermound facies, composed mainly of different types of wackestones and packstones. Individual beds containAnthracoporella andArchaeolithophyllum missouriense in growth position, forming “micromounds’. Two stages of mound formation are recognized: (1) the stabilization stage when bioclastic wackestones accumulated, and (2) the skeletal mound stage when the sea-bottom was colonized byAnthracoporella and other members of the baffler and binder guilds, formingAnthracoporella bafflestones and wackestones of the mound facies. A slight drop in sea-level led to the termination of the mound growth and accumulation of organic debris, particularly calcareous algae, fusulinids, crinoids and bryozoans, forming well bedded limestones, which overlie the mound facies  相似文献   
206.
207.
208.
209.
The Pennsylvanian stratigraphic section of the Manzanita Mountains (central New Mexico, USA) is restudied at Cedro Peak. This Pennsylvanian succession is divided into the Sandia Formation, Gray Mesa Fm, Atrasado Fm, and lower part of Bursum Fm. The sampled limestones of the Gray Mesa and Atrasado formations yielded three age-distinctive fossil assemblages: they are of (a) latest Atokan/early Desmoinesian, (b) late early Desmoinesian, and (c) middle Virgilian. The following new taxa of foraminifers are proposed: Endoteboidea n. superfam.; Spireitlinidae n. fam.; Millerellinae n. subfam.; Pseudonovella marshalli n. sp.; Pseudonovella ohioicus nom. nov.; Pseudoacutella n. gen.; Pseudoacutella hoarei nom. nov.; Plectofusulina manzanensis n. sp. Translated or emended names are: Staffelloidea, Ozawainelloidea, Ozawainellidae, and Profusulinellidae.  相似文献   
210.
RCC1 and nuclear organization.   总被引:1,自引:0,他引:1       下载免费PDF全文
  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