Memory-related changes of nitric oxide synthase activity and nitrite level in rat brain

The changes of nitric oxide synthase (NOS) activity and nitrite level in rat brain regions after spatial learning were investigated. NOS activity was assayed by conversion of [3H]L-arginine to [3H]L-citrulline, and a sensitive fluorometric assay for quantification of nitrite was used. Compared with sham-trained rats, NOS activity and nitrite level in hippocampus and cortex, and also the nitrite level in cerebellum, was elevated significantly one day after rats had learnt a water-rewarded spatial alteration task. These results suggest a spatial memory-related changes of endogenous NO in rat brain, and support the idea that NO participates in learning and memory processes.     

A genetic algorithm for multiple molecular sequence alignment

MOTIVATION: Multiple molecular sequence alignment is among the most important and most challenging tasks in computational biology. The currently used alignment techniques are characterized by great computational complexity, which prevents their wider use. This research is aimed at developing a new technique for efficient multiple sequence alignment. APPROACH: The new method is based on genetic algorithms. Genetic algorithms are stochastic approaches for efficient and robust searching. By converting biomolecular sequence alignment into a problem of searching for optimal or near-optimal points in an 'alignment space', a genetic algorithm can be used to find good alignments very efficiently. RESULTS: Experiments on real data sets have shown that the average computing time of this technique may be two or three orders lower than that of a technique based on pairwise dynamic programming, while the alignment qualities are very similar. AVAILABILITY: A C program on UNIX has been written to implement the technique. It is available on request from the authors.     

迭代回归法计算T型电位滴定中试液含量

本文将迭代回归法计算Ｔ型电位滴定中，叙述了其原理及数学推导，并运算了一批实验数据，结果表明，该法准确度较高，且不需空白溶液校正。     

灌溉与环境浅议

灌溉为人类带来了巨大的社会效益,也对环境产生了一定的不利影响,但目前对于灌溉的环境问题还处于起始阶段。文中从生态、土壤、水质、人群健康、水文地质、景观地貌等等方面分析了灌溉工程对环境的影响,试图引起人们在今后的多目标水资源开发中重视研究灌溉与环境如何达到协调平衡,为人类创造更好的生存环境。     

无机膜的应用与展望

本文综述了无机膜的发展、制备方法和应用。     

Oxygen absorption kinetics in YBa2Cu3Ox

The oxygen absorption process in highly aligned YBa₂Cu₃O_x samples in air and in pure oxygen was studied at several constant temperatures. The process can be expressed in two steps, a chemical reaction controlled step and a diffusion controlled step. The kinetic equations are as follows respectively:

(1 − a_t) ln(1 − a_t) + a_t = k_Dt

The activation energy was calculated using an Arrhenius equation. The technical conditions of heat treatment for oxygen absorption of highly aligned YBa₂Cu₃O_x crystals are discussed.     

我国聚甲醛工业的供需分析

从国内聚甲醛树脂的生产、贸易及消费状况出发 ,分析了国内聚甲醛工业的供需现状并提出短期预测。     

面向对象中文窗口开发环境：C—VISION

Ｃ－ＶＩＳＩＯＮ中文窗口系统综合采用了面向对象与窗口环境设计的程序方法，彻底更新了在微机上进行中文窗口设计的编程思想，同时作为一个基础系统，为软件设计节约了大量的人力和时间，实现了微机程序的共享。     

起重机吊钩拖动绕线电动机他励双高调速系统

本文提出励磁电流可自动控制的他励式双高调速系统设计方案。系统在提升特别是在下放重物时，具有较硬的机械性；在负载１０－１００％的变化范围内，可实现最大偏差Δｎｍａｘ／ｎｍｉｎ１００％≤１０％，调速范围Ｄ≥１０；在满载运行条件下，可节约电能８０％以上。