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   38篇
  免费   4篇
  国内免费   1篇
  43篇
  2024年   1篇
  2023年   2篇
  2022年   2篇
  2019年   2篇
  2018年   2篇
  2017年   2篇
  2016年   2篇
  2014年   4篇
  2013年   4篇
  2011年   4篇
  2010年   2篇
  2009年   1篇
  2008年   2篇
  2007年   3篇
  2006年   1篇
  2004年   2篇
  1999年   1篇
  1991年   1篇
  1981年   1篇
  1980年   1篇
  1978年   1篇
  1974年   1篇
  1973年   1篇
排序方式: 共有43条查询结果,搜索用时 12 毫秒
11.
目的:检测变应性鼻炎(Allergic rhinitis,AR)患者和健康对照者外周血中IL-10+CD4+T细胞、TGF-β+CD4+T细胞(分别代表Tr1细胞和Th3细胞的特性)的比例,并探讨其在AR发病中的意义,为AR的治疗提供临床参考。方法:分离19例对粉尘螨过敏的AR患者和19例健康对照者外周血单个核细胞(PBMCs),采用流式细胞术分别检测外周血中IL-10+CD4+T细胞、TGF-β+CD4+T细胞的比例。结果:同健康对照者相比,AR患者外周血中IL-10+CD4+T细胞的比例显著降低[(1.66±0.48)%vs.(3.80.92)%,t=-9.08,P0.01)],AR患者外周血中TGF-β+CD4+T细胞的比例降低[(1.92±0.54)%vs.(4.76±1.12)%,t=-9.94,P0.01)]。结论:外周血中IL-10+CD4+T(Tr1)细胞比例的降低可能是AR发病的一个重要因素,提高AR患者外周血中分泌IL-10的Tr1细胞的比例可能在AR的治疗中具有重要意义。外周血中TGF-β1+CD4+T(Th3)细胞的比例显著降低,可能是AR发病的一个重要因素。但TGF-β1与AR关系的研究较少,特别是外周血中TGF-β1水平与AR的关系研究较少,需进一步研究。  相似文献   
12.
虎杖光合生理生态特性日变化研究   总被引:2,自引:3,他引:2  
用Li-6400便携式光合测定系统对5个虎杖材料的光合生理特性日变化及其与气象因子关系进行了研究。结果表明:(1)虎杖的净光合速率日变化呈‘单峰’型曲线,日最大净光合速率(15.0μmol·m^-2·s^-1)值出现在9:00左右;(2)叶片水压亏缺、气孔导度和蒸腾速率的峰值在同一时间出现(13:00),胞间CO2浓度不随气孔导度的降低而减小,控制虎杖光合速率因子为非气孔限制;(3)供试5个材料的净光合速率日变化趋势基本一致,并以地栽组培苗的净光合速率最高,而‘贵州凯里’的最低。光合有效辐射对光合特征参数的变化影响最大,且对净光合速率起决定性作用(r-0.534^**),环境因子主要通过对蒸腾速率、叶片水压亏缺和叶面温度的作用来影响虎杖叶片净光合速率。  相似文献   
13.
记述中蝎蛉科Mesopanorpodidae Tillyard,19181新种,宽形中蝎蛉Mesopanorpodes latus sp.nov.。化石标本采自于陕西铜川中三叠世铜川组下段上部的灰绿色泥岩和页岩。新种属于陕西昆虫群铜川昆虫组合的新成员(属陕西动物群、陕西生物群的一个类别)。模式标本保存于北京自然博物馆标本馆。  相似文献   
14.
中国丝孢酵母属的几个新种和新记录   总被引:1,自引:0,他引:1  
作者从中国的北京、湖北等地的鸟粪,霉变柿子以及酒药中分离到了三株未描述的丝孢酵母菌。本文描述了这三个新种:板仓丝孢酵母(Trichosporon bancangense),北京丝孢酵母(Tr.beijingense)和中国丝孢酵母(Tr.sinense)并讨论了它们与属中近似种的差别。本文还发现了丝孢酵母属的4个新记录:皮刺丝孢酵母(Tr.aculeatum),埃利丝孢酵母(Tr.eriense),斐氏丝孢酵母(Tr.figueriae)和蜜二糖丝孢酵母(Tr.melibiosaceam)。  相似文献   
15.
Triostin A exists as two symmetrical conformers in weakly polar solvents like chloroform. Adenine and guanine derivatives were found to specifically interact with one of the two conformers, but uracil and cytosine derivatives did not. From the analysis of nmr and infrared spectra, it was concluded that the purine derivatives form cyclic hydrogen bonds with the alanine residue of triostin A in addition to the stacking interaction between the purine base and the quinoxaline ring.  相似文献   
16.
17.
Since its discovery in 2000, interleukin-21 (IL-21) has been shown to display a broad spectrum of pleiotropic actions including the regulation of development, differentiation and function of lymphoid-myeloid cells. More specifically, IL-21 modulates the effector functions of T, B and NK cells, which not only have key roles in antitumoral and antiviral immunity but also in exerting major effects on inflammatory responses promoting the development of autoimmune diseases. Recent studies have unveiled an unexpected role for IL-21 in immune regulation and de novo T-cell development. While highlighting its critical role in immunity, this review will mainly focus on recent advances in IL-21 biology and how such newly discovered properties could potentially be exploited therapeutically in the establishment of future clinical trials.  相似文献   
18.
19.
The chemical transformation of phosphinic acid is a well-considered mature area of research on account of the historical significant reactions such as Kabachnik–Fields, Mannich, Arbuzov, Michaelis–Becker, etc. Considerable advances have been made over last years especially in metal-catalyzed, free-radical processes and asymmetric synthesis using catalytic enantioselective. As a result, the aim of this synopsis is to make the reader familiar with advances in the approaches of phosphinic acids toward the synthesis of highly functionalized and valuable buildings blocks. Another purpose of this survey is to provide the current status of the applications of phosphinic acids in the synthesis of drugs.  相似文献   
20.
We analyzed cell viability, caspase activity, plasma membrane alterations and cell ultrastructure morphology to estimate the morphological and biochemical alterations that occur in bivalve molluscan cell cultures during cryopreservation. The use of 5% dymethyl sulfoxide as a cryoprotectant resulted in greater cell survival and a scarcity of destroyed cells lacking cytosol among dead cells. In this case, almost all cells died through necrosis or apoptosis, which appeared to increase in mussel cell cultures after a freeze-thaw cycle. Apoptosis was not a main death pathway in mussel cells, but it was induced in a significant part of these cells (up to 24%) immediately after thawing and depended mostly on the cryoprotectant used. Regardless of the type of the used cryoprotectant, we observed some nuclear aberrations in cells after freezing-thawing, such as few multipolar mitoses or the absence of a division spindle in mitotic cells. After analyzing different methods for assessing cell damage, the best results were obtained from optimal approaches that could provide information regarding the cell disruption level after freezing-thawing and could be considered for future studies.  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