面向21世纪的加氢裂化技术(续)

４多种中压加氢转化工艺取得新进展高压加氢裂化对处理重质和劣质原料,在高转化率下制取高质量油品方面具有很大的优势,但其投资、操作成本和氢气耗量都比较高。因此,在８０年代初ＵＯＰ和Ｃｈｅｖｒｏｎ公司以及ＩＦＰ等相继推出了在压力小于１０ＭＰａ下操作的缓和加氢裂化（ＭＨＣ）技术。这种技术能工业应用有两个原因,其一是有的国家特别是日本在８０年代初有闲置的ＶＧＯ中压间接脱硫装置,其二是利用中压下ＶＧＯ的缓和加氢裂化可以生产部分轻柴油和石脑油,同时也可脱除未转化油中的硫、氮,并进行芳烃部分饱和;而改质以后,作…     

一种新型智能电机节电控制器的研制

介绍了一种由８９ｃ５１单片机控制的智能电机节电控制器的工作原理,试用表明能达到较满意的节能效果,并具有较好的稳定性。     

高压圆缝泄漏数学模型及其计算机仿真

分析了高压圆环型缝隙中考虑液压油的膨胀和局部油液温升时泄漏的流量的计算模型，并依此编写了其仿真源程序，得到了压力，流量和局部油液温升沿缝隙长度方向的变化曲线。实验表明，本文分析方法所得到的计算结果与实测结果相当吻合。对高压液压系统的设计和缓冲装置的设计都具有一定的参考价值。     

不同细度滑石粉填充HDPE的研究

本文研究了不同细度滑石粉填充HDPE体系的力学性能。结果表明:随着滑石粉细度的增加、填充HDPE的拉伸强度和拉伸模量提高了、经偶联剂处理后的滑石粉的填充效果,明显优于未处理的。其中2500目滑石粉的填充效果最佳。     

梯度折射率激光准直器的原理与设计

本文研究用单块抛理型梯度折射率棒透镜作激光准直器的原理、特性和设计。     

Efficiently computing derived performance data

In this paper, we examine the problem of generating instrumentation that efficiently computes derived performance data of program execution. The instrumentation computes these derived data at run time as the directly accessible data is collected. It tests conditions defined on the collected data and eliminates the data that does not satisfy the stated conditions, thus, avoiding recording irrelevant data. We examine this problem in terms of generating instrumentation for computing the answers to monitoring questions. Our solution is based on the use of temporal conditions defined on the events in the questions to determine which data to record and to be used as relevant run time filters on the events producing that data.     

Maximizing multiprocessor performance with the SUIF compiler

This article describes automatic parallelization techniques in the SUIF (Stanford University Intermediate Format) compiler that result in good multiprocessor performance for array-based numerical programs. Parallelizing compilers for multiprocessors face many hurdles. However, SUIF's robust analysis and memory optimization techniques enabled speedups on three fourths of the NAS and SPECfp95 benchmark programs     

Human Mig chemokine: biochemical and functional characterization

Mig is a chemokine of the CXC subfamily that was discovered by differential screening of a cDNA library prepared from lymphokine-activated macrophages. The mig gene is inducible in macrophages and in other cells in response to interferon (IFN)-gamma. We have transfected Chinese hamster ovary (CHO) cells with cDNA encoding human Mig and we have derived CHO cell lines from which we have purified recombinant human Mig (rHuMig). rHuMig induced the transient elevation of [Ca2+]i in human tumor-infiltrating T lymphocytes (TIL) and in cultured, activated human peripheral blood-derived lymphocytes. No responses were seen in human neutrophils, monocytes, or Epstein-Barr virus-transformed B lymphoblastoid cell lines. rHuMig was chemotactic for TIL by a modified Boyden chamber assay but rHuMig was not chemotactic for neutrophils or monocytes. The CHO cell lines, IFN-gamma-treated human peripheral-blood monocytes, and IFN-gamma-treated cells of the human monocytic cell line THP-1 all secreted multiple and identical HuMig species as revealed by SDS-PAGE. Using the CHO-derived rHuMig, we have shown that the species' heterogeneity is due to proteolytic cleavage at basic carboxy-terminal residues, and that the proteolysis occurs before and not after rHuMig secretion by the CHO cells. The major species of secreted rHuMig ranged from 78 to 103 amino acids in length, the latter corresponding to the full-length secreted protein predicted from the HuMig cDNA. Carboxy-terminal-truncated forms of rHuMig were of lower specific activity compared to full-length rHuMig in the calcium flux assay, and the truncated species did not block the activity of the full-length species. It is likely that HuMig plays a role in T cell trafficking and perhaps in other aspects of the physiology of activated T cells.     

A homeobox gene with potential developmental control function in the meristem of the conifer Picea abies

Many homeobox genes control essential developmental processes in animals and plants. In this report, we describe the first cDNA corresponding to a homeobox gene isolated from a gymnosperm, the HBK1 gene from the conifer Picea abies (L.) Karst (Norway spruce). The sequence shows distinct similarities specifically to the KNOX (knotted-like homeobox) class of homeobox genes known from different angiosperm plants. The deduced amino acid sequence of HBK1 is strikingly similar within the homeodomain (84% identical) to the maize gene Knotted1 (Kn1), which acts to regulate cell differentiation in the shoot meristem. This similarity suggested that the phylogenetic association of HBK1 with the KNOX genes might be coupled to a conservation of gene function. In support of this suggestion, we have found HBK1 to be expressed in the apical meristem in the central population of nondifferentiated stem cells, but not in organ primordia developing at the flanks of the meristem. This pattern of expression is similar to that of Kn1 in the maize meristem. We show further that HBK1, when expressed ectopically in transgenic Arabidopsis plants, causes aberrations in leaf development that are similar to the effects of ectopic expression of angiosperm KNOX genes on Arabidopsis development. Taken together, these data suggest that HBK1 has a role, similar to the KNOX genes in angiosperms, in the control of cellular differentiation in the apical meristem of spruce. The data also indicate that KNOX-gene regulation of vegetative development is an ancient feature of seed plants that was present in the last common ancestor of conifers and angiosperms.