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201.
介绍兰州炼油化工总厂苯烃化和四聚丙烯工艺交替使用同一套装置的设计。由于两种工艺所用催化剂相同,反应机理和原料类同,所以可共用原料系统、反应系统和一些设施,节省用地4524m2。依靠技术进步,节能降耗,每年获经济效益660万元 相似文献
202.
Multimode parameter extraction for multiconductor transmissionlines via single-pass FDTD and signal-processing techniques 总被引:1,自引:0,他引:1
Yuanxun Wang Hao Ling 《Microwave Theory and Techniques》1998,46(1):89-96
We present two approaches to extract the broadband multimode parameters of guided wave structures from a single-pass finite-difference time-domain (FDTD) simulation. They include a two-dimensional (2-D) Fourier transform (FT) algorithm and a super-resolution estimation of signal parameters via rotational invariance technique (ESPRIT) algorithm. Comparison is made to show the superiority of the super-resolution approach. As a typical application, a three-line coupled microstrip structure is studied. After a single-pass FDTD simulation, broadband multimode parameters such as propagation constants, modal-field templates, and modal impedances are extracted and verified against published data obtained by the spectral-domain method. The main feature of this parameter-extraction methodology is that it decouples the computational electromagnetics engine (in this case, the FDTD simulator) from the post-processing parameter-extraction algorithm, thus providing more flexibility and connectivity among the various simulation tools 相似文献
204.
205.
Role of macrophage overactivation in the development of acute pancreatic injury in rats 总被引:1,自引:0,他引:1
PURPOSE: To report quantitative changes in the anterior chamber configuration after small-incision cataract surgery with implantation of a posterior chamber intraocular lens by means of ultrasound biomicroscopy. METHODS: We examined the anterior chamber configuration of 20 eyes of 20 patients before and 3 months after small-incision cataract surgery (phacoemulsification and aspiration plus foldable intraocular lens implantation through a 3.0- to 4.0-mm self-sealing wound) by means of ultrasound biomicroscopy. The following variables were measured: the anterior chamber depth at the center of the cornea, the angle-opening distance 250 microns from the scleral spur (AOD250), the angle-opening distance 500 microns from the scleral spur (AOD500), and the trabecular-iris angle. RESULTS: The anterior chamber depth at the center of the cornea, AOD250, AOD500, and trabecular-iris angle increased significantly after surgery. The preoperative anterior chamber depth at the center of the cornea and trabecular-iris angle were negatively correlated with the differences between the postoperative and preoperative values (P < .01). The preoperative values of all variables examined were negatively correlated with the ratios of the postoperative value to the preoperative value (P < .002). CONCLUSIONS: The present results showed that small-incision cataract surgery significantly deepened the anterior chamber and widened its angle. The more shallow the preoperative anterior chamber was, the greater the postoperative change of the chamber was; and the more narrow the preoperative angle was, the greater the postoperative change of the angle was. 相似文献
206.
提出了溅射-气体-聚集共沉积制备金属/金属(介质)复合团簇镶嵌薄膜的新方法,并利用该方法成功地在方华膜衬底上制备了系列Fe/Ag及CaF2复合团簇镶嵌薄膜样品。透射电镜分析结果表明,样品中Fe(Cu)团簇都较好地镶嵌于Ag(CaF2)基质中,其结构为两种材料的多晶共存形态。进一步分析发现,与块材相比,Fe/Ag样品中Fe团簇晶格常数呈现出不同程度的收缩,而Cu/CaF2样品中Cu团簇晶格常数则呈现出不同程度的膨胀。运用附加压力的模型对该现象进行了解释。 相似文献
207.
Previous film autoradiographic studies demonstrated that, during corticogenesis, dopamine receptors of the D1 class are abundant in the embryonic primate cerebral wall. In the present study, we expand these findings by identifying the cellular elements of the fetal occipital cerebral wall expressing D1 and D5 subtypes of the D1 dopamine receptor class. We have examined tissue from monkey fetuses collected at 70, 90 and 120 days of gestation using antibodies directed against C-termini of the D1 and D5 dopamine receptors. At all three embryonic ages studied, we found D1 and D5 receptors expressed by multiple cell types of the embryonic cerebral wall. Both D1 and D5 receptor proteins are produced by pyramidal neurons of the cortical plate and by a variety of interstitial neurons of the subplate and intermediate zones. D1 and D5 receptors are also present in cells of the proliferative ventricular and subventricular zones, some of which were identified as dividing cells. In addition, D1 and D5 receptors are detectable in the protoplasmic astroglial and ependymal cells distinguishable in monkey fetuses collected at 120 days of gestation. Some cellular elements of the embryonic monkey cerebral wall express only one subtype of the D1 dopamine receptor class. For example, embryonic Cajal-Retzius neurons in the marginal zone and migrating neurons in the intermediate zone are immunoreactive only to D5 antisera. In contrast, radial glia can be labeled only with D1 receptor-specific antisera. Finally, only D1 receptors are detectable in the blood vessels penetrating the embryonic monkey cerebral wall. Based on these observations, we propose that dopamine receptors of the D1 class play an important role in regulating cerebral cortical formation and that D1 and D5 receptor subtypes may participate in regulation of different aspects of this process. 相似文献
208.
多灰度级显示器上的曲线绘制 总被引:1,自引:0,他引:1
光栅扫描显示器的屏幕是由位置固定的,离散的象素点所组成的,因而在其上生成的曲线只能是实际曲线的某种近似表示,并不是很美观的,例如有曲线的阶梯效应及曲线亮度不均度等问题,该文说明利用多灰度光栅显露器可以在一定程度上解决这些问题,并且用给出的主些算法绘制曲线时,可以较好地解决上述问题,这些算法在动画制作中也可有典型的应用。 相似文献
209.
The narrow pore-size distribution of activated carbon fibres (ACF) limits their application in the fields concerning larger
molecules, such as liquid adsorption and catalyst support. On the addition of carbon particles and organic materials to polyacrylonitrile
fibres, and after stabilizing and activating, the mesoporosity in the resultant ACF has been obviously increased. Among these
additives, carbon black gives the best effect. With 1 wt% carbon black I in precursor and on activating at 880°C for 30 min,
a mesoporosity of 48.2% (total pore volume 0.704 ml g-1, mesopore volume 0.340 ml g-1) has been obtained. The mechanism of
mesopore formation is also discussed.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
210.
Design of finite-length metal-clad optical waveguide polarizer 总被引:1,自引:0,他引:1
Chyong-Hua Chen Likarn Wang 《Quantum Electronics, IEEE Journal of》1998,34(7):1089-1097
The performance of optical metal-clad waveguide polarizers is analyzed in this paper with a view to optimizing the extinction ratio, a condition for which power of the TM mode is completely attenuated is identified here. In general, such a condition corresponding to an infinitely high extinction ratio can be met for a wide range of buffer layer thicknesses by selection of metal film thickness and polarizer length. When a very thick (e.g., semi-infinitely thick) metal film is used, the aforementioned condition can be met with a properly chosen buffer layer thickness and polarizer length. The numerical results show that all the polarizers designed here for realization of infinitely high extinction ratios have either quite low or reasonably acceptable attenuations for the TE mode 相似文献