Y-152和K-156在果蝇ADH催化中的作用

果蝇醇脱氢酶酪氨酸－１５２（Ｙ－１５２）和赖氨酸－１５６（Ｋ－１５６）处于同类脱氢酶的保守位点。经人工定点突变和酶动力学分析,前者的苯丙氨酸（Ｙ１５２Ｆ）、组氨酸（Ｙ１５２Ｈ）和谷氨酸突变体（Ｙ１５２Ｅ）及后者的异亮氨酸突变体（Ｋ１５６Ｉ）均丧失催化活性。而半胱氨酸－１５２（Ｙ１５２Ｃ）及精氨酸－１５６（Ｋ１５６Ｒ）突变体活性分别是对应野生型的０．２５％和２．２％。此外,Ｙ１５２Ｃ和Ｋ１５６Ｒ的Ｋ     

关于σ-局部可数弱基

证明如下主要定理：（１）σ－局部可数弱基在开、闭Ｌｉｎｄｅｌｏｆ映射下保持．（２）设Ｘ、Ｙ有σ－局部可数弱基，则Ｘ×Ｙ为ｋ－空间的充分必要条件是下列之一满足：（α）Ｘ和Ｙ有σ－局部可数基，（ｂ）Ｘ或Ｙ为局部紧度量空间，（Ｃ）Ｘ、Ｙ有－σ－局部有限且由紧子集构成的弱基．     

1—苯基—3—甲基—4—（α—呋喃甲酰基）—5—吡唑酮与中性萃取剂协同萃取钇（Ⅲ）的研究

本文研究了１－苯基－３－甲基－４－（α－呋喃甲酰基）－５－吡唑酮（ＨＡ）单独萃取Ｙ（Ⅲ）及其与二苯亚砜（ＤＰＳＯ），磷酸三丁酯（ＴＢＰ）或三辛基氧膦（ＴＯＰＯ）协同萃取Ｙ（Ⅲ）的行为。确定了萃合物的组成分别为ＹＡ＿３，ＹＡ＿３·ＤＰＳＯ，ＹＡ＿３·ＴＢＰ和ＹＡ＿２（ＮＯ＿３）·２ＴＯＰＯ．算得萃取平衡常数分别为：ｌｏｇＫ＿（Ａ（ＨＡ））＝－６．８６，１ｏｇＫ＿（ＡＢ（ＨＡ＋ＤＰＳＯ））＝－３．８９，ｌｏｇＫ＿（ＡＢ（ＨＡ＋ＴＢＰ））＝－２．５３和ｌｏｇＫ＿（ＡＢ（ＨＡ＋ＴＯＰＯ））＝５．１３．     

稀土钇对含Zn和Mg铸态铝合金相组成物的影响

研究了Ｙ在Ａｌ－（１－５）％Ｙ,Ａｌ－８％Ｚｎ－（１－５）％Ｙ,Ａｌ－２％Ｍｇ＿１－３）％Ｙ及Ａｌ－８％Ｚｎ－２％Ｍｇ－（０－５）％Ｙ合金中的存在形态及对该合金铸态组织的影响。结果表明,在Ａｌ－Ｙ及Ａｌ－２％Ｍｇ－Ｙ合金中,Ｙ以Ａｌ３Ｙ形态存在;在Ａｌ－８％Ｚｎ－２％Ｍｇ和Ａｌ－８％Ｚｎ合金中以Ｙ１２Ａｌ３Ｚｎ金属间化合物的形态存在下晶界,在Ａｌ－８％Ｚｎ－２％Ｍｇ中,Ｙ的存在还能改变Ｚｎ和Ｍｇ在     

K—NUC空间与LK—NUC空间

证明了（１）若Ｘ,Ｙ分别是Ｋ１－ＮＵＣ空间、Ｋ２－ＮＵＣ空间,１〈Ｐ〈＋∞,则（Ｘ＋Ｙ）ｐ为（Ｋ１＋Ｋ２－１）－ＮＵＣ空间。（２）若Ｘ,Ｙ分别是ＬＫ１－ＮＵＣ空间,ＬＫ２－ＮＵＣ空间,１〈Ｐ〈＋∞,则（Ｘ＋Ｙ）Ｐ为Ｌ（Ｋ１＋Ｋ２－１）－ＮＵＣ空间。（３）引入了ＬＫ－ＷＨ性质,并得到具有ＬＫ－ＷＨ性质的ＬＮＵＣ空间与ＬＫ－ＮＵＣ空间等价。     

B（X，Y）上的σ－弱连续泛函

给出了Ｂ（Ｘ，Ｙ）上的σ－弱连续泛函的表示定理，证明了当Ｙ自反时，（Ｂ（Ｘ，Ｙ）．）≌Ｂ（Ｘ，Ｙ）。     

JSY2000－26（DES－3Y）数字程控用户交换机取得入网许可证

ＪＳＹ２０００－２６（ＤＥＳ－３Ｙ）数字程控用户交换机取得入网许可证１９９５年１１月，由邮电第六实验工厂自行研制开发生产的ＪＳＹ２０００－２６（ＤＥＳ－３Ｙ）数字程控交换机通过了邮电部生产定型鉴定并取得了入网许可证。受邮电部科技司委托，邮电部教育司学...     

Sol—Gel法制备ZrO2超微粉末的反应机理研究

以自制Ｚｒ（ＯＣ３Ｈ７）４的Ｙ（ＣＨ３ＣＯＯ０３为原料，应用溶胶－凝胶法制备了ＹＳＺ（ＺｒＯ２－９）ｍｏｌ％Ｙ２Ｏ３）凝胶和超细粉末。研究了Ｓｏｌ－Ｇｅｌ形成机理以及ＰＨ值艰胶凝时间和凝胶结构的影响。     

Ti—Al—Y三元系相图1000℃部分等温截面重新确定

利用扩散偶局部平衡原理，通过金相观察和电子探针微区成分分析，重新测定了１０００℃下Ｔｉ－Ａｌ－Ｙ三元部分等温截面相图。首次发现该系在１０００℃存在两个三元化合物均相区Ｙ（ＡｌｘＴｉ１－ｘ）２（ｘ＝８０％￣１００％）和Ｙ３（ＡｌｘＴｉ１－ｘ）２（ｘ＝８０％￣１００％）改变了以前发表的关于Ｔｉ－Ａｌ－Ｙ三元相图１０００℃等温截面的研究结果。此外在所测部分等温截面相图中存在６个单相区，９个两相平衡区，４     

Sol－Gel法制备ZrO_2超微粉末的反应机理研究

以自制Ｚｒ（ＯＣ３Ｈ７）４和Ｙ（ＣＨ３ＣＯＯ）３为原料，应用溶胶－凝胶法（Ｓｏｌ－Ｇｅｌ）制备了ＹＳＺ（ＺｒＯ２－９ｍｏｌ％Ｙ２Ｏ３）凝胶和超细粉末．研究了Ｓｏｌ－Ｇｅｌ形成机理以及ｐＨ值对胶凝时间和凝胶结构的影响．通过ＴＧ－ＤＴＡ、ＸＲＤ等分析手段，研究了从干凝胶到ＹＳＺ超细粉末过程中的反应机理．实验证明：反应可分为３个阶段，钇稳定立方相ＺｒＯ２的合成温度在４７０℃左右     

在线检测彩电基板色度通道的系统性能

彩电基板的色度通道测试与调试是该基板测试与调试系统的一部分．用于流水线上的调试设备，是自动调试的前期准备．该系统也可用于彩电基板的综合测试．本文主要介绍色度通道测试的要求．基本原理和方法．色度通道白色度放大与分离，解调副载波的形成，色度信号的同步解调，消色与ＰＡＬ开关信号组成．本文对每个电路的工作特点都作了简要介绍，为后面的内容介绍时有一个整体了解．该系统由单片机测量与控制、微机处理、机电控制、测试信号及模拟信号处理、夹具等六大部分组成，文中对它们在系统中的作用作了简要说明．     

DCS-偶氮胂作为钙络合滴定指示剂的研究

本文研究了DCS—偶氮胂作为钙络合滴定指示剂的可能性,提出了判断指示剂在等当点前后颜色变化的新判据——颜色指数。该判据简便适用。     

Chromatic sensitivity of ganglion cells in the peripheral primate retina

Visual abilities change over the visual field. For example, our ability to detect movement is better in peripheral vision than in foveal vision, but colour discrimination is markedly worse. The deterioration of colour vision has been attributed to reduced colour specificity in cells of the midget, parvocellular (PC) visual pathway in the peripheral retina. We have measured the colour specificity (red-green chromatic modulation sensitivity) of PC cells at eccentricities between 20 and 50 degrees in the macaque retina. Here we show that most peripheral PC cells have red-green modulation sensitivity close to that of foveal PC cells. This result is incompatible with the view that PC pathway cells in peripheral retina make indiscriminate connections ('random wiring') with retinal circuits devoted to different spectral types of cone photoreceptors. We show that selective cone connections can be maintained by dendritic field anisotropy, consistent with the morphology of PC cell dendritic fields in peripheral retina. Our results also imply that postretinal mechanisms contribute to the psychophysically demonstrated deterioration of colour discrimination in the peripheral visual field.     

Scotopic colour vision in nocturnal hawkmoths

Humans are colour-blind at night, and it has been assumed that this is true of all animals. But colour vision is as useful for discriminating objects at night as it is during the day. Here we show, through behavioural experiments, that the nocturnal hawkmoth Deilephila elpenor uses colour vision to discriminate coloured stimuli at intensities corresponding to dim starlight (0.0001 cd x m(-2)). It can do this even if the illumination colour changes, thereby showing colour constancy-a property of true colour vision systems. In identical conditions humans are completely colour-blind. Our calculations show that the possession of three photoreceptor classes reduces the absolute sensitivity of the eye, which indicates that colour vision has a high ecological relevance in nocturnal moths. In addition, the photoreceptors of a single ommatidium absorb too few photons for reliable discrimination, indicating that spatial and/or temporal summation must occur for colour vision to be possible. Taken together, our results show that colour vision occurs at nocturnal intensities in a biologically relevant context.     

Selective habituation shapes acoustic predator recognition in harbour seals

Predation is a major force in shaping the behaviour of animals, so that precise identification of predators will confer substantial selective advantages on animals that serve as food to others. Because experience with a predator can be lethal, early researchers studying birds suggested that predator recognition does not require learning. However, a predator image that can be modified by learning and experience will be advantageous in situations where cues associated with the predator are highly variable or change over time. In this study, we investigated the response of harbour seals (Phoca vitulina) to the underwater calls of different populations of killer whales (Orcinus orca). We found that the seals responded strongly to the calls of mammal-eating killer whales and unfamiliar fish-eating killer whales but not to the familiar calls of the local fish-eating population. This demonstrates that wild harbour seals are capable of complex acoustic discrimination and that they modify their predator image by selectively habituating to the calls of harmless killer whales. Fear in these animals is therefore focused on local threats by learning and experience.     

函数连接型神经网络在氟化物非晶态形成条件中的应用

函数增强型神经网络(Functional Link Net,简称FLN)是一种无隐含层的新型网络,应用其三阶联合激励增强特性来对三元体系氟化物非晶态形成条件进行识别研究,识别准确率近100%.在对预测集的每一个输入信号添加10%的噪音干扰后,发现识别率依然不变.直到噪音添加到15%,仍然能准确判别.可见网络的容错能力是十分令人满意的.     

关于小信号鉴频的研究

本文以相位鉴频器为例,给出了小信号时的鉴频公式.同时通过选取检波器二极管的最佳偏压点,一方面调整小信号时谐振电路的Q值,选取最佳工作状态;另一方面又增大检波器的电压传输系数.从而达到提高小信号鉴频的灵敏度,并改善鉴频失真的目的.     

Is colour vision possible with only rods and blue-sensitive cones?

At night all cats are grey, but with the approach of dawn they take on colour. By starlight, a single class of photoreceptors, the rods, function, whereas by daylight, three classes, the blue-, green- and red-sensitive cones, are active and provide colour vision. Only by comparing the rates of quantal absorption in more than one photoreceptor class is colour vision possible. Although the comparisons generally take place between the cones, they can involve the rods as well. Here we investigate the wavelength discrimination of an extremely rare group of individuals, blue-cone monochromats, who have only rods and one class of cones. We find that these individuals can distinguish wavelengths (440 to 500 nm) in the twilight region where the rods and blue-sensitive cones are simultaneously active.     

SWFM-IM彩色电视双伴音光纤传输系统

本文叙述SWFM-IM彩色电视双伴音光纤传输系统的基本原理和主要性能。该传输系统可以在一根光纤上同时传输1路彩色电视视频信号和2路伴音信号或数字信号,具有接收灵敏度高、传输距离长、失真小的特点,且能满足传输立体声的质量要求。