加隔离板的两天线间隔离度计算

计算了未加隔离板时的两天线间的直射射线的分别在面方向图和面方向图时的场强强度,再对加隔离板后的两天线间分别计算了两个方向图的一次散射射线的场强强度及二次散射射线的场强强度.     

两种蟋蟀同工酶的比较研究

用聚丙烯酰胺凝胶电泳方法分析石首棺头蟋（Ｌｏｘｏｂｌｅｍｍｕｓｅｑｕｅｓｔｒｉｓ）与泰康棺头蟋（Ｌ．ｔａｉｃｏｕｎ）的酯酶（ＥＳＴ）和苹果酸脱氢酶（ＭＤＨ）同工酶．两种蟋蟀的ＥＳＴ和ＭＤＨ同工酶酶谱极为相似．其中ＥＳＴ酶谱可分为４个区带组,推测受４个位点控制．因这两种蟋蟀的形态特征极为相似,两种同工酶酶谱也比较相似,而且控制ＥＳＴ的位点数相同,因此推测两者的亲缘关系比较接近,极有可能为近缘种     

Genetic linkage of ecological specialization and reproductive isolation in pea aphids

The evolution of ecological specialization generates biological diversity and may lead to speciation. Genetic architecture can either speed or retard this process. If resource use and mate choice have a common genetic basis through pleiotropy or close linkage, the resulting genetic correlations can promote the joint evolution of specialization and reproductive isolation, facilitating speciation. Here we present a model of the role of genetic correlations in specialization and speciation, and test it by analysing the genetic architecture of key traits in two highly specialized host races of the pea aphid (Acyrthosiphon pisum pisum; Hemiptera : Aphididae). We found several complexes of pleiotropic or closely linked quantitative trait loci (QTL) that affect key traits in ways that would promote speciation: QTL with antagonistic effects on performance on the two hosts are linked to QTL that produce asortative mating (through habitat choice). This type of genetic architecture may be common in taxa that have speciated under divergent natural selection.     

Relationship between echolocation frequency and body size in two species of hipposiderid bats

Frequencies of echolocation calls with maximum power of Himalayan leaf-nosed bats and Horsfield’s leaf-nosed bats during searching phase were 74.1 and 92.1 kHz, respectively. Head-body length, forearm length and body mass of Himalayan leaf-nosed bats were 82.9 mm, 89.7 mm and 59.1 g, respectively; and the corresponding values of Horsfield’s leaf-nosed bats were 68.4 mm, 61.3 mm and 19.7 g, respectively. Echolocation frequency and the three parameters of body size, head-body length, forearm length and body mass, were all negatively correlated, and the correlation coefficients were −0.86, −1.58 and −2.19, respectively. This study thereby proved that echolocation frequency and body size were negatively correlated in the two species of hipposiderid bats.     

单克隆抗体亲和渗滤法制备两种牛生殖激素

在本室已获得高特异抗牛促卵泡激素 (bFSH)和抗牛促黄体激素 (bLH)杂交瘤细胞的基础上 ,制备纯化抗bFSH和抗bLH两种单克隆抗体 (McAbs) ,并进而建立了一种单抗免疫亲和渗滤新技术。使用该技术成功地制备了上述两种牛生殖激素 ,从 7g牛垂体干粉可提取 3.3mg亲和纯bFSH和 1 1 .1mg亲和纯bLH。回收率分别为 85 %和 82 %。     

四种佛蝗染色体核型与C带带型研究

采用染色体Ｃ带技术，对剑角蝗科（Ａｃｒｉｄｉｄａｅ）佛蝗属（ＰｈｌａｅｏｂａＳｔａｌ）的僧帽佛蝗（Ｐ．ｉｍｆｕｍａｔａＢｒ．－Ｗ、白纹佛蝗（Ｐ．ａｌｂｏｅｍａＺｈｅｎｇ）、短翅佛蝗（Ｐ．ａｕｇｕｓｔｉｄｏｒｓｉｓＢｏｌ．）、长角佛蝗（Ｐ．ａｎｔｅｎｎａｔａＢｒ．－Ｗ．）四个种的染色体进行了常规核型和Ｃ带带型分析研究，绘制了Ｃ带核型示意图二结果表明，四种佛蝗的染色体数都为２ｎ＝２３．具有２～３对大型，５～７对中型，２～３对小型染色体．这四个种的主要区别表现在Ｃ带核型的差异上．Ｃ带带型差异可反映种间的分类关系．     

No supernovae associated with two long-duration gamma-ray bursts

It is now accepted that long-duration gamma-ray bursts (GRBs) are produced during the collapse of a massive star. The standard 'collapsar' model predicts that a broad-lined and luminous type Ic core-collapse supernova accompanies every long-duration GRB. This association has been confirmed in observations of several nearby GRBs. Here we report that GRB 060505 (ref. 10) and GRB 060614 (ref. 11) were not accompanied by supernova emission down to limits hundreds of times fainter than the archetypal supernova SN 1998bw that accompanied GRB 980425, and fainter than any type Ic supernova ever observed. Multi-band observations of the early afterglows, as well as spectroscopy of the host galaxies, exclude the possibility of significant dust obscuration and show that the bursts originated in actively star-forming regions. The absence of a supernova to such deep limits is qualitatively different from all previous nearby long-duration GRBs and suggests a new phenomenological type of massive stellar death.     

土壤中多环芳烃的降解与土壤酸度及微生物的关系

利用碳酸钙调节土壤pH值,研究土壤中多环芳烃(菲、苯并[α]芘)污染物的降解情况.在控温、控光的培养室里进行为期15d的避光培养试验.试验设计5种处理试验,观察到土壤中菲、苯并[α]芘的可提取浓度都有减少,降解率分别为13.3%～52.2%、0.9%～35.3%.不同pH值土壤中,菲、苯并[α]芘的降解机制不同,中性土壤有利于菲的降解,酸性土壤有利于苯并[α]芘的降解.同时,土壤中的微生物生物量碳的大小能够反映菲、苯并[α]芘的降解情况.土壤自身具有减少稠环芳烃含量的自然能力.如果改变环境条件促进微生物的活性,就可以加速土壤中微生物对稠环芳烃的消解.     

Recognition of a chromosome truncation site associated with alpha-thalassaemia by human telomerase

Telomeres define the ends of chromosomes; they consist of short tandemly repeated DNA sequences loosely conserved in eukaryotes (G1-8(T/A)1-4). Telomerase is a ribonucleoprotein which, in vitro, recognizes a single-stranded G-rich telomere primer and adds multiple telomeric repeats to its 3' end by using a template in the RNA moiety. In conjunction with other components, telomerase may balance the loss of telomeric repeats due to DNA replication. Another role of telomerase may be the de novo formation of telomeres. In eukaryotes like Tetrahymena, this process is an integral part of the formation of macronuclear chromosomes. In other eukaryotes this process stabilizes broken chromosomes. A case of human alpha-thalassaemia is caused by a truncation of chromosome 16 that has been healed by the addition of telomeric repeats (TTAGGG)n. Using an in vitro assay, I show here that human telomerase correctly recognizes the chromosome 16 breakpoint sequence and adds (TTAGGG)n repeats. The DNA sequence requirements are minimal and seem to define two modes of DNA recognition by telomerase.     

具有时滞和密度制约的两种群相互作用模型的稳定性

研究了食饵与捕食者两种群生态系统的稳定性，给出了该系统在正平衡点处无条件稳定的充要条件，并讨论了其开关现象     

两种群相互竞争的具有非线性传染率的SIS模型

研究了两种群相互竞争的具有非线性传染率的自治类型的SIS传染病模型,得到了一些平衡点稳定与否的阈值条件。揭示了当两种群共存但无疾病交又传染时。在一定条件下疾病就会消亡的规律。     

带有扩散的两种群时滞生态模型的振动性

对用偏泛函微分方程组所描述的密度分布非均匀的两种群相互作用生态模型进行了讨论 .通过利用时滞泛函微分不等式 ,研究了时滞生态模型的振动性 ,得到了其解关于正平衡态振动的简捷的充分判据 .     

Adaptive evolution drives divergence of a hybrid inviability gene between two species of Drosophila

Speciation--the splitting of one species into two--occurs by the evolution of any of several forms of reproductive isolation between taxa, including the intrinsic sterility and inviability of hybrids. Abundant evidence shows that these hybrid fitness problems are caused by incompatible interactions between loci: new alleles that become established in one species are sometimes functionally incompatible with alleles at interacting loci from another species. However, almost nothing is known about the genes involved in such hybrid incompatibilities or the evolutionary forces that drive their divergence. Here we identify a gene that causes epistatic inviability in hybrids between two fruitfly species, Drosophila melanogaster and D. simulans. Our population genetic analysis reveals that this gene--which encodes a nuclear pore protein--evolved by positive natural selection in both species' lineages. These results show that a lethal hybrid incompatibility has evolved as a by-product of adaptive protein evolution.