低压复合开关的设计与应用

低压复合开关充分利用电力电子器件晶闸管在开、关断中无电弧和磁保持继电器触头接触电阻小和保持原状态无损耗的优点。电路设计方面采用晶闸管与磁保持继电器相结合的方式,能实现电压过零时投入,电流过零时断开。利用微型单片机芯片对电路进行智能控制,能达到电路多种通信模式与灵活制定工作方式的目的,并添加安全性能极高的保护电路。通过对该开关试验运行,证明研制设备的可靠性。     

电气工程及其自动化低压电器中继电器的应用

继电器在电路系统中应用的非常广泛,是一种典型的控制元件,电流一旦达到了其设定的线圈动作数值,那么继电器的触头就会做出相应的动作,实现预先设定的功能,完成对整个电路的的控制。继电器的广泛使用对于电气工程及其自动化低压电器有着非常深远的意义,本文围绕着这个主题进行了探讨。     

浅析过压保护技术在智能模糊控制系统中的应用

本文集中讨论了铝电解控制中的智能模糊控制系统对过电压的保护技术,分析了过压保护继电器在槽控机中的有关应用和技术特点,着重探讨了电压保护继电器应用于铝电解生产的模糊控制系统中的工作原理和实施过程。     

螺旋榨油机故障的排除

螺旋榨油机多用于压榨大豆、菜籽、棉籽、花生仁、芝麻等,是农村小型油坊理想的榨油机械。由于各种原因,螺旋榨油机有时会出现出油少甚至不出油等故障,必须及时予以排除。     

浅谈飞机液压系统设计中的压力冲击问题

在飞机液压系统设计中,减少系统中的压力冲击,对于提高飞机的操纵品质和安全性具有重要意义。本文整理了飞机液压系统压力冲击抑制设计需求来源,分析了飞机液压系统压力冲击的产生机理,并给出了抑制压力冲击的设计要点。     

继电器在电气工程及其自动化低压电器中的应用

当前,电气工程的规模在科学技术不断发展以及社会不断进步的形势下日趋扩大,数量也越来越多,其中自动化低电压设备的使用较为普遍,然而受限于许多因素的影响,低电压设备在实际运用当中难免会出现这样那样的故障,对电气工程的顺利进行形成了阻碍,因此必须运用有效措施实施保护,而在自动化低电压设备保护当中,继电器成为了首选设备,这得益于继电器的功能特性十分良好。为此,本文着眼于继电器的工作原理和作用,从继电器的常用类型出发,对其在电气工程和自动化低压电器当中的具体应用做一些探讨。     

浅谈水电厂常用三种转速继电器的原理及应用

本文对水电厂现在所常用的三种转速继电器(离心式转速继电器、齿盘测速继电器、残压测速继电器)的原理、特点及出现过的问题进行比较和分析,给出评价和改造建议。     

浅谈水电厂常用三种转速继电器的原理及应用

本文对水电厂现在所常用的三种转速继电器(离心式转速继电器、齿盘测速继电器、残压测速继电器)的原理、特点及出现过的问题进行比较和分析,给出评价和改造建议。     

多功能SF6密度继电器三通阀的应用探究

运行的SF6气体密度继电器由于停电和不易拆卸等原因,长期运行后会出现动作不灵活、触点接触不良等现象,从而易导致SF6密度继电器误动作,因此有必要对继电器进行定期校验。为此,本文以多功能SF6密度继电器三通阀为对象,介绍了三通阀的设计方案,SF6设备在安装三通阀后能够得以在不停电、不拆卸的情况下实现对其继电器的校验。     

西门子7SJ68综保在炼油部的应用

论述7SJ68保护装置相对传统继电器保护的优点及在天津石化炼油部的应用。     

商会自治的基石——商会自治规范研究

在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。     

癸氧喹酯干混悬剂含量测定的改进

采用高效液相色谱法测定癸氧喹酯干混悬剂的含量,在2-250μg/mL范围内,峰面积的常用对数与进样量浓度的常用对数呈良好的线性关系,R^2=1(n=5),平均回收率为99.24%~99.51%,RSD在0.05%~0.28%。此方法分析时间短,样品前处理简便、定量结果准确,重现性好,结果满意,为其质量控制提供了依据。     

猪毛色遗传的研究进展

本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。     

Comparison of 2 methods of centesis of the bursa of the biceps brachii tendon of horses

REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air.     

不同样本商品蜂蜜中硒含量的测定

用硝酸和高氯酸消化蜂蜜,使硒游离出来,在微酸性环境下,硒和2,3-二氨基萘(DAN)生成有较强荧光的物质,用环己烷萃取,在激发波长378nm,荧光波长518nm处测定其荧光强度。蜂蜜中硒含量范围:0.10～0.82μg/g。表明:蜂蜜应视为天然富硒营养品。     

乳酸杆菌益生作用机制的研究进展

乳酸杆菌作为益生菌广泛用于人和动物。本文综述了乳酸杆菌改善宿主健康的机制。乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道。文章重点讨论了乳酸杆菌表面成分（表面蛋白、脂磷壁酸和肽聚糖）与肠道受体（Ｃ型凝集素受体、Ｔｏｌｌ样受体和 Ｎｏｄ样受体）,阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制。     

中华人民共和国农业部公告 第267号

为贯彻落实《兽药生产质量管理规范》(简称《兽药GMP》),进一步推动兽药GMP实施进程,我部制定了《兽药生产质量管理规范检查验收办法》,现予公告。本公告自2003年6月1日起施行。附件:兽药生产质量管理规范检查验收办法二○○三年四月十日第一章 总则 第一条 为推动《兽药生产质量管理规范》(以下简称兽药GMP)的实施,规范兽药GMP检查验收工作,制定本办法。 第二条 农业部负责全国兽药GMP管理和检查验收工作;负责制修订兽药GMP检查验收管理规定;负责兽药GMP检查员队伍建设和监督管理工作,负责国际兽药贸易中GMP互认工作。 …     

鸡败血支原体垂直传播模式及其阻断方法

以国际标准强毒Ｒ株人工感染非免疫产蛋鸡,定时扑杀,分别从鼻窦、眶下孔、气管、肺、气囊、卵巢和输卵管分离ＭＧ,并收集感染鸡所产蛋分离ＭＧ。结果表明,人工感染４８小时后上、下呼吸道及肺已被全面感染,９６小时气囊已被感染,１２０小时输卵管已能分离到ＭＧ,卵巢始终分离不到ＭＧ。人工感染鸡自１４４小时便能在其所产蛋中分离出ＭＧ。药物治疗能在７２小时内消除感染,油乳剂苗则需２４天后逐渐降低蛋内ＭＧ分离率,药物卵内注射、种蛋药浴、高温处理均能杀死卵内ＭＧ,但以研制的种蛋浸泡剂药浴效果为最好。     

Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF

Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo.