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41.
Conchostracans and corixids are part of the diet of extant salamanders,an ecologically important fact in a lacustrine environment. Here we report their discovery in the guts of the aquatic Jurassic salamanders Jeholotriton paradoxus and Chunerpeton tianyiensis, formerly abundant at Daohugou,Ningcheng County,Inner Mongolia,China.This reveals something of the ecology of this im- portant,ancient,vertebrate and invertebrate assemblage.The new fossil evidence indicates the highly selective feeding of these Jurassic salamanders;Jeholotriton preyed only on juveniles of the conchostracan Euestheria luanpingensis,and Chunerpeton only on the corixid Yanliaocorixa chinensis.We can infer the dietary differences as a consequence of different jaw and hyoid structures; and thus niche partitioning in Jurassic salamanders.  相似文献   
42.
月地高速再入返回飞行试验任务目标是验证与半弹道跳跃式返回再入的相关技术,全面可靠的获取试验相关数据,对试验结果评估至关重要,为此飞行器专门设计实现了一套包括力、热、图像等参数采集与存储的工程参数测量系统,本文给出了该系统的设计情况及飞行结果.  相似文献   
43.
Two kinds of noise strategies in binary opinion dynamics on ER random networks are discussed. Random noise p1 in the initial configuration plays a role in redistributing the opinion states associated with the network. Under synchronous updating, the system can attain a stable state within few time steps. The fraction of nodes with changed opinion states F decreases exponentially with time, and the ratio of one of the two opinion states R remains almost unchanged during the evolution. The average ratio c...  相似文献   
44.
The level of atmosphericΔ14C and the fossil fuel derived CO 2 concentration in the Beijing area from May to September,2009, were systematically analyzed based on radiocarbon(14C)measurements of annual plants by accelerator mass spectrometry(AMS). The results show that the maximumΔ14C in Beijing was 29.6‰±2.2‰,and the minimum was–28.2‰±2.5‰,with a trend of decreasingΔ14C from the outer suburbs to inner suburbs to the urban center.This trend correlates well with increases in fossil fuel derived CO2 caused by human activities such as population density,industrial emissions and traffic,with lower values of atmosphericΔ14C associated with more intensive human activities.The fossil fuel derived CO 2 concentrations from May to September, 2009,ranged from 3.9±1.0 ppm to 25.4±1.0 ppm.It was calculated that each additional 1 ppm of CO2 from fossil fuels depleted the atmosphericΔ14C by approximately 2.70‰.This study suggests that 14C measurements of annual plants by AMS provide an effective method to rapidly trace fossil fuel derived CO2.  相似文献   
45.
Three variants of the sequence of formation of the nacre-prism transition layer were observed in Pinctada fucata (Bivalvia, Mollusca) shells. In each case, the layer was formed by the organic matrix secreted by the mantle, together with the interprismatic organic envelope. The continuity of the organic phase throughout the shell was maintained as the new nacreous layer was formed on the nacre-prism transition layer. Changes in the interprismatic organic envelopes on either side of the nacre-prism transition...  相似文献   
46.
酒名有商标、分商标、特殊质料、扩展、功能、适用场合(或对象)、类型等7个主要结构成分,11种结构模式。酒名对11种模式的利用不是均等的,模式5、模式6和模式7是基本结构模式。酒名的用字特点突出,国俗词语、地名、人名、文化典籍等常用来命名酒名。  相似文献   
47.
介绍一种考场身份验证系统,就其系统功能、构成及使用方法进行说明。此系统将指纹识别技术应用于考生身份的识别中,保证了识别的准确性,公正性,并且节省人力,使用方便,便于考生的计算机管理;可以杜绝“替考”一类作弊事件的发生。  相似文献   
48.
For the past two decades,great achievements have been made in cancer research of China and the majority of them were supported by the National Natural Science Foundation of China(NSFC).In this article,we reviewed the funding history of NSFC including the number of proposals,the amount of grants,distribution of supported program categories during the period of 1987 to 2012 and the representative achievements made by continuous support of NSFC.Also,the impacts of NSFC support on discipline development and talent fostering were analyzed.From 1987 to 2012,a total of 8738 proposals related to cancer research were funded by NSFC.The percentages of the Research Program,Talent-Training Program,and the Research Environment Program were 61.19%,36.32%,and 2.49%,respectively.Under the support of NSFC,cancer research in China has achieved a significantly rapid and balanced development in both disciplines and scientist resources.  相似文献   
49.
A chiral complex of (R,R)-Pd was prepared by reaction of optically pure (R,R)-bis(pyrrol-2-ylmethyl-eneamino) cyclohexane ligand with Pd(OAc)2·2H2O under the base condition at room temperature. The weak intermolecular C-H···Pd interaction was found to be responsible for the homochiral M helix for-mation of the neutral,chiral,mononuclear (R,R)-Pd in the crystal packing.  相似文献   
50.
本文概述了植物体内与K^ 转运相关的蛋白及其基因,包括通道蛋白(channel protein)和转运体(transporter)及其基因,前者可分为:(1)内向整流K^ 通道(inward-rectifying K^ channel:Kin^ ),(2)外向整流K^ 通道(outward-rectifyjng K^ channel :Kout^ );相关基因有AKTI,ANTI,SORK,GORK等.后者分为低亲和K^ 吸收转运体及高亲和K^ 吸收转运体;相关基因有HAK,KUP等.  相似文献   
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