用环形激波聚焦实现爆轰波直接起爆的数值模拟

利用基元反应模型和有限体积法对环形激波在可燃气体中聚焦实现爆轰波直接起爆进行了数值模拟.研究结果表明,标准状态下的氢气-空气混合气体在马赫数为3.1以上的环形激波聚焦产生的高温高压区作用下会诱发可燃气体的直接起爆形成爆轰波,爆轰波与激波和接触间断相互作用产生了复杂的波系结构;爆轰波爆点位置在对称轴上并不是固定的点,而是随着初始激波马赫数的变化而发生移动;可燃气体初始温度和压力对起爆临界马赫数都有影响,但是初始温度的影响大得多.

Influence of threshold stress on the estimation of the Weibull statistics

The influence of threshold stress on the estimation of the Weibull statistics is discussed in terms of the Akaike information criterion. Numerical simulations show that, if sample data are limited in number and threshold stress is not too large, the two-parameter Weibull distribution is still a preferred choice. For example, the fit of strength data of glass and ceramics to the two- and three-parameter Weibull distributions is compared.

不同长度β_2整合素_M亚基与ICAM-1的亲和性比较

国家自然科学基金项目(30730032/10702075)

Dynamic full-range Fourier-domain optical coherence tomography using sinusoidal phase-modulating interferometry

We propose a technique for dynamic full-range Fourier-domain optical coherence tomography by using sinusoidal phase-modulating interferometry, where both the full-range structural information and depth-resolved dynamic information are obtained. A novel frequency-domain filtering algorithm is proposed to reconstruct a time-dependent complex spectral interferogram from the sinusoidally phase-modulated interferogram detected with a high-rate CCD camera. By taking the amplitude and phase of the inverse Fourier transform of the complex spectral interferogram, a time-dependent full-range cross-sectional image and depth-resolved displacement are obtained. Displacement of a sinusoidally vibrating glass cover slip behind a fixed glass cover slip is measured with subwavelength sensitivity to demonstrate the depth-resolved dynamic imaging capability of our system. (c) 2007 Society of Photo-Optical Instrumentation Engineers.

High-efficiency diffraction gratings in fused silica at the wavelength of 632.8 nm

We describe high-efficiency diffraction gratings fabricated in fused silica at the wavelength of 632.8 nm by rigorous coupled-wave analysis (RCWA). High-density holographic gratings, if the groove density falls within the range of 1575-1630 lines/mm and the groove depth within the range of 1.1-1.3 microns, can realize high diffraction efficiencies at the wavelength of 632.8 nm, e.g., the first Bragg diffraction efficiency can theoretically achieve more than 93% both in TE- and TM-polarized incidences, which greatly reduces the polarization-dependent losses. Note that with different groove profiles further optimized, the maximum efficiency of more than 99.69% can be achieved for TM-polarized incidence, or 97.81% for TE-polarized incidence.

Infrared broadband emission of bismuth-doped barium-aluminum-borate glasses

We report near infrared broadband emission of bismuth-doped barium-aluminum-borate glasses. The broadband emission covers 1.3 mum window in optical telecommunication systems. And it possesses wide full width at half maximum (FWHM) of similar to 200nm and long lifetime as long as 350 mus. The luminescent properties are quite sensitive to glass compositions and excitation wavelengths. Based on energy matching conditions, we suggest that the infrared emission may be ascribed to P-3(1) --> P-3(0) transition of Bi+. The broad infrared emission characteristics of this material indicate that it might be a promising candidate for broadband optical fiber amplifiers and tunable lasers. (C) 2005 Optical Society of America.

辽宁省抚须石新世木化石群的初步研究

我国古新世植物化石发现较少，因而目前对古新世的植被面貌;生态环境等植物学;植物地理学和地质学方面的认识尚感不足。抚顺古新过木化石群的研究提供了这方面的新资料无疑在植物学;质植物地理学和地质学等方面都有一定意义。 本研究表明，抚顺古新世木化石群皆由松柏目Pinales裸子植物组成，共有三科七属七种和三个未定种。其中杉科Taxodiaceae三属三种和一个未定种，松科Pinaceae和柏科Cupressaceae各二属二种和一个未定种。共有四个新种。本化石群的地质时代被确定为古新世。通过对此化石植物群的研究，作者认为右新世时抚顺地区存在着以杉和柏科植物为主体的北亚热带一北温暖带边缘地带暖性针叶林。根据孢粉资料(木化石未见)同时还有繁盛的被子植物存在。当时当地的生态环境类似我国现今长江流域南部偏北地带，如川鄂;江浙一带的山地，系属亚热带山区气候。 此外，根据新的化石资料，本文还对扁柏型木属Chamaecyparioxylon做了补充修正，报导了木化石中真菌菌丝的发现。它被初步鉴定为藻状菌纲毛霉目 Mucorales真菌。

涡鞭毛虫类的染色质碱性蛋白研究及其进化地位的重新认识

通过对涡鞭毛虫这一特殊生物类群的染色质碱性蛋白研究的综述,并结合作者近来的工作和国际上有关的最新进展,对这类生物染色质碱性蛋白的特殊性和多样性进行了阐述。在此基础上对这类生物进化地位及系统发育进行了探讨。认为其染色质碱性蛋白不应是组蛋白的祖先蛋白,相反,它们是一些由于次生的原因而替代了组蛋白的碱性蛋白,并由于替代蛋白的不同而形成了它们的次生多样性;其染色质的特性即是由此而形成的与真细菌类核体的趋同相似性;其进化地位并非以前所认为的位于原核生物向真核生物的过渡环节,这类生物应是在真核细胞的基础上由于次生原因而形成的特殊类群;其系统发育也正是这一次生物进化过程的反映。

宁夏新建二代防护林网蛀干害虫发生特点和危害特性

本文以宁夏银川二代林网中林分和害虫调查资料为基础 ,研究了二代林网主要蛀干害虫——光肩星天牛 (Anoplophora glabripennis Mostch)和木蠹蛾 [Cossus cossus ori-entalis Gaede &H olcocerus vicarius(Walker) ]分别在新疆杨林和刺槐林中因不同的树龄、径粗、林向、郁闭度、林地类型 (林缘和林内 )而呈现出的相应发生特点和为害特性。结果显示 ,新疆杨大于 6年生、胸径超过 1 2 cm径阶受光肩星天牛危害频率高 ;实验用片林林缘到林内 2 m范围内新疆杨受光肩星天牛危害显著高于林内 ,而东、西、南、北 4个方向 ,以东边受害最轻 ;与其它树种组成的混交林林缘同样重于林内。刺槐易受木蠹蛾危害的树龄和径节分别是 6 a～ 1 2 a和 1 2 cm～ 2 0 cm;刺槐片林无论是纯林还是混交林均为林缘重于林内。以上蛀干害虫对树龄和径粗均有较强的一致性选择

滇池控藻围隔中水生植物和浮游藻类对不同形态铁浓度的影响

运用围隔试验来研究围隔生态系统内浮游藻类的组成和数量以及水生植物变化对不同形态铁浓度的影响,再反过来探讨微量元素铁在蓝藻水华暴发过程中对水生植物和浮游藻类生态生理的作用,从而为探索治理蓝藻水华的新途径提供基础证据。从2003年6月至10月,定期采样测定了控藻围隔水体中的亚铁、颗粒态铁(>0.22μm)、小胶体态铁(0.22～0.025μm)、溶解态铁(<0.025μm)的浓度和叶绿素a的浓度,同时对浮游藻类进行了组成鉴定和细胞计数。结果表明,不同形态的铁之间是可以相互转化的,胶体态铁比颗粒态铁活跃,是溶解

鱊头槽绦虫原尾蚴皮层的超微结构观察

利用透射电镜观察了头槽绦虫 (Bothriocephalusacheilognathi)原尾蚴皮层的超微结构。头槽绦虫原尾蚴的皮层为典型的合胞体结构。皮层表面有浓密的微毛与少量的突起。与成虫相比 ,原尾蚴的微毛长而且粗 ,呈现单态性 ,推测在进入终末宿主的过程中有脱落和再生现象。突起分布在头部与体侧 ,含有较少的电子致密颗粒。在原尾蚴皮层细胞质中观察到三种腺细胞的分泌过程 ,即顶分泌、外分泌和微分泌过程。原尾蚴身体后部观察到尾钩和穿刺腺管道的开口。在核周区和纤维层下可见发育较好的环肌与纵肌。本文还对原

ALGAL GROWTH POTENTIAL AND NUTRIENT LIMITATION IN SPRING IN THREE-GORGES RESERVOIR, CHINA

In China, especially in Three-Gorges Reservoir, our knowledge of the algal growth potential and nutrient limitation was still limited. In the spring of 2006, the water column ratios of total nitrogen/total phosphorus were investigated and algal bioassays performed to determine algal growth potential of waters and nutrient limitation of mainstream and Xiangxi Bay of Three-Gorges Reservoir. The results showed sampling sites in mainstream were co-limited by N and P or P-limited alone, and sites in Xiangxi Bay were N-limited alone. Fe likely played an important role in determining the appearance and disappearance of algal blooms of Three-Gorges Reservoir. Native algae, Pseudokirchneriella subcapitata and Cyclotella meneghiniana, had high growth potential in Three-Gorges Reservoir.