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   3篇
  国内免费   10篇
  2020年   1篇
  2018年   1篇
  2017年   1篇
  2016年   1篇
  2015年   1篇
  2013年   1篇
  2009年   1篇
  2007年   1篇
  2006年   1篇
  2005年   1篇
  2004年   4篇
  2003年   3篇
  2002年   2篇
  2001年   5篇
  2000年   6篇
  1999年   3篇
  1996年   4篇
  1995年   2篇
  1994年   4篇
  1993年   3篇
  1991年   2篇
  1988年   2篇
  1982年   1篇
排序方式: 共有51条查询结果,搜索用时 15 毫秒
31.
7, 8-dihydroxyflavone (7, 8-DHF), a selective agonist for TrkB receptors, has been well studied for its neurotrophic functions. However, its roles outside the neural tissues have scarcely been studied as yet. In this study, we investigated the protecting roles of 7, 8-DHF in EA.hy926 cells, a human umbilic vein endothelial cell line which was exposed to hydrogen peroxide (H2O2). We found that 7, 8-DHF significantly protected the cells from being damaged by H2O2 through suppression of apoptosis, attenuation of inflammatory factor releasing and inhibition of reactive oxygen species generation. The potent biological effects of 7, 8-DHF were probably executed via its binding to TrkB receptors because the receptor specific antagonist ANA-12 significantly blocked its protecting effects. The protecting roles of 7, 8-DHF in EA.hy926 cells suggest that it will be a promising compound to be developed into a health product that definitely benefits endothelial functions and prevents cardiovascular diseases.  相似文献   
32.
中华鳖幼体呼吸代谢的初步研究   总被引:8,自引:0,他引:8  
本文利用改装后的Kalabukhov-Skvorstov呼吸器,同时测定了中华鳖在自由潜水状态下的空气呼吸和水呼吸摄氧量。结果表明:在正常生活状态下,中华鳖主要依靠空气呼吸摄氧;水呼吸仅占总呼吸摄氧量为2.68%左右。呼吸摄氧率无显著昼夜变化。  相似文献   
33.
水产养殖过程中,氮素积累日益严重,而其中亚硝酸盐由于转化速度低,毒性强,对养殖的危害更加突出。对从对虾养殖池中通过反硝化条件选择性富集培养得到的具有去除硝酸盐及亚硝酸盐能力的细菌进行筛选,结果分离到27株能够还原硝酸盐的异养细菌,其中24株在7d内能有效地降低硝酸盐和亚硝酸盐浓度;特别是LZX22、LZX27、LZX23、LZX21等4株使硝酸盐氮由起始的422.25mg/L降至4.00mg/L以下,亚硝酸盐浓度也降至0.40mg/L以下。对这些菌株进行16S rDNA系统发育分析,结果显示:27株菌分属于5个不同的类群,α-Proteobacteria(1),γ-Proteobacteria(10),Actinobacteria(12),Firmicutes(3),和Bacteroides(1);它们在系统发育上分别与11个属相近,分别是Pseudomonas,Halomonas,Acinetobacter,Paracoccus,Arthrobacter,Microbacterium,Cellulosimicrobium,Bacillus,Stenotrophom,和Sphingobacterium。表明所分析的虾池中具有去除硝酸盐和亚硝酸盐能力的细菌具有较高的多样性,特别是多株细菌为首次报道具有去除硝酸盐和亚硝酸盐的能力,为下一步筛选亚硝酸盐高效去除细菌提供了丰富的菌种资源。  相似文献   
34.
Regulation of thermogenic activity and uncoupling protein1 (UCP1) expression in brown adipose tissue (BAT) were studied in euthermic Daurian ground squirrel after acute and chronic cold exposure at 4°C. The UCP1 concentration was indirectly determined by titration with its specific ligand [3H]-labeled GTP, and Ucp1 mRNA was detected by using a [32P]-labeled antisense oligonucleotide probe. Both acute and chronic cold exposure stimulated up-regulation of Ucp1 mRNA. Although UCP1 concentration is not significantly increased after 24 h of cold exposure, it is markedly elevated by 75% in squirrels after 4-week cold adaptation compared with controls raised at 22°C. Changes in T4 5′-deiodinase activity were closely associated with variations of Ucp1 mRNA level. Ucp1 gene expression is significantly affected by cold exposure in BAT from euthermic Daurian ground squirrels. In addition, the activation of T4 5′-deiodinase may be an important regulatory factor in cold-induced Ucp1 expression.  相似文献   
35.
田鼠属动物婚配制度的研究范式   总被引:14,自引:2,他引:12  
从社会组织的生态格局、熟悉性、社会等级和交配近况等择偶行为的影响因子,性二型和雄性射精能力等个体特征,配对关系的神经内分泌机制几方面综述了田鼠动物婚配制度的研究进展,同时从生态学、比较心理学、生理学、神经生物学等方面探讨择偶行类节式的特点。生态学方法,用鼠动物具有完整的婚配制度多样性格局,是婚配制度比较研究的哺乳动物类群。运用比较心理学方法,通过择偶行为实验可直接比较单配制与较研究的理想哺乳动物类  相似文献   
36.
褪黑素与绵羊的季节性生殖   总被引:3,自引:0,他引:3  
石琼  孙儒泳  张崇理 《生态学报》2000,20(5):863-868
绵羊是一种短光照型生殖动物,具有明显的生殖季节性。人们普遍认为,绵羊生殖周期与环境光周期的同步变化是通过褪黑素作用于下丘脑-垂体-性腺轴系统来实现的。近年来的不少研究结果表明,绵羊对光周期的感受性还受褪黑素受体的调控。现从生态学(光周期的生殖效应)、神经内分泌学和分子生物学(褪黑素受体)等领域的研究进展出发,对褪黑素调控绵羊自然季节性生殖的作用及机制进行系统综述。  相似文献   
37.
Understanding reproductive behavior is important for the conservation of endangered species, but research on the reproductive behavior of Sunda pangolins (Manis javanica Desmarest, 1822) is still very scarce. In this study, we used focal animal sampling and all-occurrence recording by an infrared monitor to observe the behaviors of two Sunda pangolins during a 5-day breeding period at the Pangolin Research Base for Artificial Rescue and Conservation Breeding of South China Normal University (PRB-SCNU). The behavioral characteristics and breeding strategies were analyzed, and the results were discussed together with information on other captive Sunda pangolin pairs at PRB-SCNU. The results found that there was no obvious estrus behavior in the captive female, while the male could exhibit sexual excitement and courtship behavior after a brief introduction period. Repeated copulation continued over many days after the female accepted the courtship. The average duration of copulatory behavior was 248.9 ± 148.7 s (n = 25), and all copulation occurred between 20:00 and 08:00 hr in the natural day–night photoperiod. The mating position of Sunda pangolins was lateral–ventral and was classified as the ninth or eleventh pattern under both Dewsbury's and Dixson's classification systems. This study can provide scientific guidance for the captive breeding and management of Sunda pangolins and other pangolin species, which is of great significance for ex situ conservation tactics.  相似文献   
38.
鲇鱼的静止代谢率及其与体重,温度和性别的关系   总被引:15,自引:3,他引:12  
采用连续流水式呼吸仪测定了127尾鲇鱼(体重22.6-452.4g)的静止代谢率。在10,15,20,25和30℃水温下,鲇鱼平均特定体重代谢率分别为22.99,58.55,79.20,109.29和123.89mgO2/kg/h。体重(W)与静止代谢率(Ms)回归关系(Ms=aW^b)的体重指数b随温度上升而下降,温度(T)与特定体重代谢率(M')回归关系(M'=AT^B)的温度指数B随体重增加  相似文献   
39.
布氏田鼠数量和空间分布的年际动态及周期性初步分析   总被引:5,自引:1,他引:5  
布氏田鼠的分布特点是避开山丘,季节河河床和芨芨草滩;主要分布在季节河两侧,分布区缩小时,向季节河两侧收缩,布氏田鼠年动态是否有周期性尚难以下最后的结论,但存在季节动态是可以肯定的,布氏田鼠在其地理分布中心区和边缘区的种群年际动态可能存在差异,中心区的种群动态相对可能稳定些,边缘区的种群波动可能大些。  相似文献   
40.
高原鼠兔蒸发失水的地位及热能调节   总被引:9,自引:4,他引:5  
王德华  王祖望 《兽类学报》1993,13(2):104-113
本文对高原鼠兔(Ochotona curzoniae)的静止代谢率(RMR)、蒸发失水(EWL)、非颤抖性产热(NST)等能学参数进行了测定,计算了干燥热传导(dry C)、热能调节热标(TI)等,评估了蒸发散热(EHL)在热传导(C)中的地位,结果表明:高原鼠兔的基础代谢率(BMR)和最小热传导(C_m)均高于期望值;25℃以上EHL占有重要地位;热能调节能力较好,但抗高温能力较差;这些特征对于栖居在年气温差较小、日温差大的高寒环境中的高原鼠兔具重要的适应意义。  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