基于MODIS NDVI的长江中游区域植被动态及与气候因子的关系

基于1999-2015年的MODIS NDVI时间序列遥感数据，应用趋势分析、变异系数、重标极差分析和偏相关分析等方法，分析了长江中游的植被时空变化特征及其与气象因子的关系。结果表明，长江中游地区NDVI均值总体上呈上升趋势（从0.72增加到0.80）。从空间分布来看，NDVI低值区域（0.1-0.5）占1.40%，高值区域（>0.7）占87.15%；NDVI空间格局呈"西高东低、北高南低"的分布特征，低值区域表现为以三省省会城市为中心向外辐射。Hurst指数显示，研究区大部分区域（60.54%）的NDVI变化趋势具有不确定性，持续性改善区域（34.78%）主要分布在西部山地区，持续性退化区域（3.26%）主要分布在人类活动频繁的较发达城市区域。在年际尺度上，研究区NDVI与各气象因子关系均不显著；月际尺度上，NDVI与降水、相对湿度和日照时数显著相关，降水和日照时数有明显的时滞性。区域内NDVI动态趋势以不确定性发展为主，城市群周边NDVI呈现持续退化的区域应该引起关注。     

Genome‐wide scans to detect positive selection in Large White and Tongcheng pigs

Due to the direction, intensity, duration and consistency of genetic selection, especially recent artificial selection, the production performance of domestic pigs has been greatly changed. Therefore, we reasoned that there must be footprints or selection signatures that had been left during domestication. In this study, with porcine 60K BeadChip genotyping data from both commercial Large White and local Chinese Tongcheng pigs, we calculated the extended haplotype homozygosity values of the two breeds using the long‐range haplotype method to detect selection signatures. We found 34 candidate regions, including 61 known genes, from Large White pigs and 25 regions comprising 57 known genes from Tongcheng pigs. Many selection signatures were found on SSC1, SSC4, SSC7 and SSC14 regions in both populations. According to quantitative trait loci and network pathway analyses, most of the regions and genes were linked to growth, reproduction and immune responses. In addition, the average genetic differentiation coefficient F_ST was 0.254, which means that there had already been a significant differentiation between the breeds. The findings from this study can contribute to further research on molecular mechanisms of pig evolution and domestication and also provide valuable references for improvement of their breeding and cultivation.     

电刺激猫小脑顶核对动脉血压和肾交感神经放电的影响

在38只麻醉及人工呼吸的猫,观察到电刺激小脑顶核嘴侧部能引起动脉血压显著升高;肾交感神经放电于刺激期间显著增加。去缓冲神经对刺激顶核所引起的血压反应的幅度和肾交感神经放电均无明显影响,但可明显延长血压反应升高相以及血压恢复期的时间。静脉注射氯庄定引起血压降低、心率减慢及肾交感神经放电的抑制,并能减弱刺激顶核引起的血压反应,但增强了刺激顶核引起的肾神经放电的变化。电解损毁延髓腹外侧面引起血压降低及肾交感神经放电的抑制,然而无论单侧还是双侧损毁延髓腹外侧面都不能阻断刺激顶核所引起的血压和肾交感神经放电的反应。以上结果表明,电刺激顶核能引起明显的心血管反应,其反应的下行性通路可能不通过延髓腹外侧面。     

温度、pH及效应剂对高粱PEP羧化酶活性的协同作用

纯化的高粱PEP羧化酶活性随pH升高(pH6.6～8.0)而增大。在G6P和Mal存在下,酶活性仍有随pH升高而增大的趋势,但G6P对酶的激活百分率和Mal的抑制百分率随pH升高而降低。高粱PEP羧化酶活性的最适温度高于40℃、酶的催化效率(V_(max)/K_m)随温度升高而增大。高温下,反应激活能降低,Mal对酶活性抑制百分率亦随温度升高而下降,I_(0.5)值增大,Mal增大K_m(PEP)的效应变小。     

The reconciliation behavior of golden monkeys (Rhinopithecus roxellanae roxellanae) in small breeding groups

Observations were made following 130 spontaneous aggressive incidents in two small breeding groups of captive golden monkeys (Rhinopithecus roxellanae roxellanae). Participants were observed both during the first 10 min following these incidents and during matched control observations. An increased contact rate was observed between opponents following the aggressive incident. Post-conflict contacts were characterized by a number of behavior patterns: open mouth, rapid grooming, embrace, and crouching. Adult males played an important role as mediator in agonistic disputes among females: males intervened in 93.6% of female fights. It is speculated that this intervention behavior is related to the species' organization into one-male units.     

Hidden smectic properties of a chiral side-chain co-oligomer

We recently showed that a side-chain industrial co-oligosiloxane presents a quenchable enlarged blue phase behaviour at the cholesteric-isotropic phase transition. In this paper, we present the results of a structural study based on X-ray diffraction, differential scanning calorimetry and optical measurements. In particular, the smectic A organisation is demonstrated in the lower temperature domain, which was hitherto understood as a cholesteric phase. A structural model for this phase is proposed on the basis of the analysis of the anisotropic scattering of stretched fibers. Our results also suggest that the observed glass transition is indeed a rather complex phenomenon, which seems to involve not only the freezing of the main chains, but also smectic correlations at the side-chain level. Moreover, the calorimetric study indicates that, notwithstanding the conservation of the processed film's optical properties, low kinetic reorganisations occur at room temperature.     

雄貉睾丸宽度和血清睾酮水平的季节性变化及其与某些繁殖特性的关系

作者测定并分析了43只雄貉睾丸宽度、血清睾酮水平的季节性变化。结果表明:睾丸宽度和血清睾酮水平呈明显的年周期季节性变化(p<0.01)。秋分(9月)时,睾丸宽度开始增大(p<0.05 );血清睾酮水平在10月开始升高(p<0.05)。各月雄貉的平均睾酮水平与平均睾丸宽度是极显著的正相关(r=0.83,p<0.01 n=11)。雄貉繁殖季节初期,血清睾酮水平与其首、末次的交配日期呈显著负相关(r=-0.525和r=-0.476,p<0.05,n=19)。     

刺激家兔尾核对丘脑束旁核痛兴奋和痛抑制单位放电的影响

在51只清醒麻痹家兔身上,记录了丘脑束旁核痛兴奋(PfPE)和痛抑制(PfPI)单位的放电。观察刺激尾核头背部(DHCN)对 PfPE 和 PfPI 单位自发放电和痛放电的影响。(1)刺激 DHCN时,在28个 PfPE 单位中,19个的自发放电发生抑制反应,7个无变化,2个增强;在6个PfPI 单位中,5个的自发放电增加,1个无变化。(2)刺激 DHCN 时,在38个 PfPE 单位中。2个的痛放电兴奋增强,6个无变化,30个被抑制。其中12个呈抑制反应的单位,8个立即发生在刺激 DHCN 之后,并延续700—1600ms,在10个 PfPI 单位中,7个的痛放电发生兴奋反应,3个无变化。这些结果提示,DHCN 对丘脑 PfPE 和 PfPI 单位在处理痛觉信息上具有调制作用。根据抑制的潜伏期短和延续时间长的特点,推测这种调制作用可能既通过直接通路又有间接环路参与。     

花背蟾蜍(Bufo raddei Strauch)眼形态发生过程中角膜上皮表面结构的扫描电镜观察

扫描电镜观察表明,花背蟾蜍眼形态发生过程中角膜上皮细胞表面形态结构的变化,大致可分三个阶段。1.从神经管期至肌肉感应期预定角膜上皮表面无明显变化;2.在心跳期和鳃血循环期预定角膜上皮表面出现较多的细胞缢束和其下细胞表面的下陷;3.在以后各期,角膜上皮中纤毛细胞的纤毛逐渐退化消失,在右鳃盖封闭期纤毛细胞全部消失。上述变化与视网膜及其中光感受器的发育分化密切相关,纤毛的退化和消失更精确地反映了这种依赖关系,似可作为角??膜上皮分化的一个形态指标。