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41.
The release of ovarian oxytocin and uterine prostaglandin (PG)F2alpha in response to an oestradiol stimulus was investigated. On Day 15 post-oestrus, ten ewes with ovarian auto-transplants (n=5 per group) received an intra-muscular injection of either oestradiol benzoate (50 microg) or vehicle. Blood samples were collected from the ovarian and jugular veins at 30 and 0 min before, and at 15-min intervals up to 540 min after, injection. The secretion rate of ovarian progesterone remained elevated in four of five treated ewes and in all control ewes, indicating the presence of a functional corpus luteum. Peripheral oestradiol concentrations were significantly (P < 0.001) higher in treated than in control ewes. The number of ewes that released pulses of ovarian oxytocin > or =240 min following oestradiol benzoate injection was significantly (P < 0 05) greater than that in control ewes. Mean amplitude and area under both ovarian-vein oxytocin and jugular-vein 15 keto-13,14 dihydro prostaglandin F2alpha (PGFM) pulses were significantly increased in the treated ewes. These findings demonstrate that the administration of exogenous oestrogen provides a positive stimulus for the release of ovarian oxytocin and uterine PGF2alpha in the ovarian auto-transplanted ewe. 相似文献
42.
We have isolated a putative serine/threonine receptor kinase gene with an expression pattern indicating that it may play a role in the stylar response to pollination. Differential display PCR was used to select tobacco mRNAs with increased accumulation following pollination. NTS16, a cDNA identified by this method, is homologous to a ca. 2.4 kb mRNA primarily expressed in pistil tissues. Levels of this mRNA increase during floral development and are further increased by pollination reaching maximal accumulation 12-18 hours after pollination and then declining. mRNA levels can also be increased by the application of ethylene to unpollinated flowers. A polypeptide encoded by the NTS 16 open reading frame has sequence similarity to the catalytic domain of several receptor protein kinases from plants including the S-receptor kinases implicated in the rejection of self-pollen in Brassica species and the Pto gene product of tomato which confers resistance to a bacterial pathogen. 相似文献
43.
随着计算机技术的发展和水平的提高,图像,声音,图形等多媒体信息逐步应用于管理信息系统之中。文章中提出了图文数据库系统设计中存在的三个基本问题。讨论了介绍了图文数据库系统的设计方法和实现技术。 相似文献
44.
由电压型运算放大器组成的精密整流电路要严格地匹配电阻才能获得精密全波整流波形.本文给出一种具有CCⅡ电路特性由运算放大器AD844所构成的电流模精密整流电路.无需匹配电阻就可输出良好的精密全波整流波形.且具有输入电压范围大,频带宽等特点. 相似文献
45.
46.
This paper redefines three measures of element s-importance for 2-state systems regardless of s-coherence, presents the calculation methods of these measures, and gives a new method to calculate the system time-specific failure and recovery frequencies. A poor point in the literature in extending methods for evaluating the s-importance of elements of s-coherent system to non-coherent system is pointed out. An example illustrates these definitions and calculation methods. 相似文献
47.
本文简单地回顾了提高VLSI测试效率所采用的一些手段,讨论了在ASIC测试问题研究中出现的一些新观点、新方法、新动向,以及所取得的成果。在此基础上,文章阐明了ASIC测试技术的发展方向,并着重论述了可望在未来得到发展的,针对ASIC的功能测试方法。 相似文献
48.
Haitao Zhang Zonghai Chen Yongji Wang Ming Li Ting Qin 《International Journal of Adaptive Control and Signal Processing》2006,20(2):53-76
Laguerre Functional Model has many advantages such as good approximation capability for the variances of system time‐delay, order and other structural parameters, low computational complexity, and the facility of online parameter identification, etc., so this model is suitable for complex industrial process control. A series of successful applications have been gained in linear and non‐linear predictive control fields by the control algorithm based on Laguerre Functional Model, however, former researchers have not systemically brought forward the theoretical analyses of the stability, robustness, and steady‐state performance of this algorithm, which are the keys to guarantee the feasibility of the control algorithm fundamentally. Aimed at this problem, we introduce the principles of the Incremental Mode Linear Laguerre Predictive Control (IMLLPC) algorithm, and then systemically propose the theoretical analyses and proofs of the stability and robustness of the algorithm, in addition, we also put forward the steady‐state performance analysis. At last, the control performances of this algorithm on two different physical industrial plants are presented in detail, and a number of experimental results validate the feasibility and superiority of IMLLPC algorithm. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
49.
The Tikhonov regularisation technique is widely used in the solution of inverse scattering problems. One of the difficulties in applying this technique is the proper selection of the associated regularisation parameter. Based on a stochastic model of the reconstruction process, a simple method is presented for selecting this parameter for an efficient implementation of various microwave imaging methods 相似文献
50.
Sun Linzhi Luo Yi Zhang Yanan Sun Ping Qin Xinjie Gong ZhenbangPrecision Machinery Institute Shanghai University Shanghai China 《机械工程学报(英文版)》2002,15(4):303-307
An experimental bimorph piezoelectric element (PZT) actuator for small pipe robot is developed. The robot can move in φ20 mm pipe, and can carry a CCD camera for detecting cracks or fine holes on inner surface of pipe. The velocity of the robot can reach 17~22 mm/s for vertical pipe up/down, respectively. Moving principle and its performance characteristics are presented. 相似文献