开发功能性畜产品

遗传工程的技术现在已广泛地用于生命科学、医学、药学等领域。通过遗传工程学的研究不仅可以解开生命之谜,还能够解开蛋白质构造和机能之间的关系,并通过克隆技术提高乳、肉、蛋的品质和产量,使一些可以作为药品的稀少的活性物质有可能大量生产,从而替代某些脏器、组织产生的这些活性物质,为人类所利用。这就是通过分子生物学手段开发功能性畜产品的创举。畜产品利用的分子生物学研究首先,畜产品的微生物开发利用,其中大多数的研究和开发均和乳酸菌有关。现在对乳酸菌的利用除了乳酪、发酵食品的利用以外,盛行开发能够调节肠胃、有…     

Rediscovery of the Neotoma population on Datil [Turner] Island, Sonora, México

On Datil [Turner] Island in the Gulf of California, we rediscovered a population of Neotoma varia, previously thought to be extinct. We captured 5 specimens: 1 was kept as a voucher, and 4 were examined and released. Analysis of previous surveys indicates that N. varia is not common on the island and occupies a very restricted range. Recolectamos especímenes de Neotoma varia de la Isla Dátil en el Golfo de California, una población anteriormente considerada ya extinta. De los cinco especímenes que recolectamos, cuatro se pusieron en libertad. El análisis de muestreos previos indica que N. varia no es común en la isla y que tiene una distribución muy limitada.     

双层多晶FLOTOX E2PROM的阈值电压退化特性

基于FLOTOX E^2PROM结构,分析了影响FLOTOX E^2PROM可靠性的主要因素,包括可编程窗口退化、电荷保持特性退化及与时间有关的隧道氧化层击穿(TDDB)等,发现FLOTOX的可靠性与隧穿氧化层的质量密切相关．实验表明,擦／写电压应力周期、脉;中电压应力大小及脉冲宽度的变化都会影响FLOTOX E^2PROM阈值电压的变化,分析认为隧穿氧化层中产生的缺陷(陷阱电荷)是引起FLOTOX E^2PROM阈值电压退化的主要原因,隧道氧化层中的陷阱电荷通过影响注入电场使阈值电压增加或减少．     

稀疏随机点积图中三角形数量的极限定理

研究了具有随机顶点向量的稀疏随机点积图中三角形数量的渐近行为,其中顶点之间的边概率与顶点向量的乘积成某种比例关系.当顶点数趋于无穷时,证明了三角形数量的渐近分布收敛到泊松分布.     

科技热门概念辨析之二(技术篇)

正本文是"科技热门概念辨析"系列文章之二——技术篇,介绍"技术"的定义、特点、分类,分析技术与工程、技术与专利、技术与科学的关系,并就当下人们极为关心的前沿技术、颠覆性技术谈谈我的认识。一什么是技术技术(technology)一词来自希腊语,指技能、手的技巧,所谓熟能生巧,巧就是技术。技术也被称作"技艺的科学"或"工艺科学"(science of craft)。     

科技热门概念辨析之三(研发篇)

正引言本篇是"科技热门概念辨析"系列文章的最后一篇(1)。在辨析有关"科学"和"技术"的热门概念之后,我们需要对"研究与开发"(简称"研发")进行一些研讨。这里介绍了研发的定义和特点、研发活动的分类及其任务,讨论关于"预先研究"的概念与实践,并对研发的战略、策略问题谈了笔者的一点认识。不当之处,敬请指正。一什么是研发研发就是研究与开发(research and     

红外遥控键盘的计算机接口电路

介绍了红外遥控发射器ＤＡ５０４８和接受器ＤＡ５０５０芯片的特性及其与ＭＣＳ－５１系列单片机系统的接口电路,并给出了软件识别键码的方法和汇编了程序。     

Action mechanisms of a new erythrocyte-derived depressing factor

To investigate the action mechanisms of a new erythrocyte-derived depressing factor (EDDF), the focus is placed on the effect of EDDF on both cytosolic and nuclear free calcium (Ca²⁺) transportation in vascular smooth muscle cell (VSMC), as well as the apoptosis and cell cycle of VSMC of rats. EDDF has been extracted from human erythrocytes. The changes of Ca²⁺ levels in cytoplasm ([Ca²⁺]_i) and nucleus ([Ca²⁺]_n) have been observed using a laser scanning confocal microscope together with fluo-3/AM as a calcium indicator. Flow cytometric technique was used to study the effect of EDDF on cell cycle and apoptosis of VSMC. [Ca²⁺], and [Ca²⁺]_n were significantly decreased through several different pathways: ( i ) it reduced the Ca²⁺ influx by blocking L-type voltage-dependent calcium channel (L-VDC) and R-type voltage-dependent calcium channel (R-VDC); (ii) it inhibited the Ca²⁺ release from inositol 1, 4, 5-trisphosphate (IP₃) sensitive calcium store; and (iii) activated Ca²⁺-ATPase of sarcoplasmic reticulum (SR) and promoted the transportation of Ca²⁺ from cytoplasm to SR. However, EDDF seemed to have little inhibitory effect on the Ca²⁺ release from ryonodine sensitive calcium pool. It was also found that EDDF (10⁻⁴ g/mL) significantly decreased the proportion of S phase of human umbilical vein (HUV) and inhibited the proliferation of VSMC induced by angiotensin II (Angll, 10⁻⁵ mol/L). The apopotosis did not occur when VSMC was cultured under normal condition. While VSMC apoptosis was induced by Angll (10⁻⁵ mol/L) and EDDF (10⁻⁴ g/mL) seemed to have little effect on it. The inhibitory effect of EDDF on the elevation of [Ca²⁺]_i and [Ca²⁺]_n of VSMC might play an essential role in its action mechanisms and the ways it affects the Ca²⁺ handling of VSMC demonstrate that EDDF was different from other endogenous blood pressure regulators and some known antihypertensive drugs. EDDF could inhibit the proliferation of VSMC, which indicated that it might be beneficial to the prevention and treatment of hypertension and arteriosclerosis.     

组氨酸的Keggin结构杂多金属氧酸盐的合成及性质研究

首次合成了组氨酸的Ｋｅｇｇｉｎ结构（ＸＭ１２Ｏ４０＾ｎ－,Ｘ＝Ｐ,Ｓｉ,Ｍ＝Ｗ,Ｍｏ）３种杂多金属氧酸盐化合物,用元素分析、ＩＲ、ＵＶ、ＴＧ－ＤＴＡ等方法对标事物进行了表征,结果表明该类化合物仍保持Ｋｅｇｇｉｎ结构、杂多酸阴离子和氨基酸靠静电作用相结合。     

深小锥孔零件无芯棒开式冷挤压刚塑性边界分析

运用场论及流体动力学的理论,分析了深小锥孔零件无芯棒开式冷挤压的变形特点,给出了该变形过程非稳态速度场的瞬时流函数方程,并由流函数方程建立了运动学许可速度场。分析了影响速度场变化的主要因素,从位置和形式2方面确定了刚塑性变形区边界和速度间断线方程。