利用高能中微子探索宇宙线起源之谜

<正>一、引言早在1912年,科学家就观测到了宇宙线,其主要成分是质子(约90%)和氦核(约9%)的高能微观粒子。迄今为止,观测到的宇宙射线中最高能量接近3×10²⁰电子伏特,约等于48焦耳,相当于一颗时速150千米的网球的动能。一个直径远远小于原子的微观粒子被加速到如此惊人的宏观能量,比地球上最大的粒子加速器LHC所能产生的最高能量大7到8个量级。这让我们很自然地产生疑问：如此高能的宇宙线来自哪里？它们是怎么被加速到这么高能量的？     

THERMODYNAMIC AND PARTICLE-DYNAMIC STUDIES ON SYNTHESIS OF SILICA NANOPARTICLES USING MICROWAVE-INDUCED PLASMA CVD

1. Introduction1.1 Silica nanoparticles and synthesis methods Silica (SiO2) nanoparticles are widely used in industry asan active filler for polymer reinforcement, a rheologicaladditive in fluids, a free flow agent in powders, and anagent for chemical mechanical polishing during IC (inte-grated circuit) fabrication (Sniegowski & de Boer, 2000).Silica powder is also used for producing silicon carbide(Koc & Cattamanchi, 1998) or opaque silica aerosols (Leeet al., 1995). Many methods can …     

OFDMA中继系统中基于QoS保证的资源分配算法

研究了 OFDMA 中继下行链路通信系统中的动态资源分配问题,提出了一种可以保证用户最低 QoS 需求的资源分配算法.首先在简化资源优化问题的过程中,采用等功率分配方法以降低算法复杂度,然后通过拉格朗日松弛优化方法推导出了子载波分配和中继选择最优解,并在此基础上引入用户速率权衡因子,根据速率权衡因子越大的用户,越具有选择子载波和中继的优先权这一准则进行子载波分配和中继选择.仿真结果表明:新算法能够获得较高的系统容量,同时也能很好地保证不同用户的最低速率需求.     

基于傅里叶模方法的KDP晶体镀膜减反技术

 采用傅里叶模方法,分析了单点金刚石铣削后KDP晶体表面小尺度波纹的周期和幅值对单层增透膜折射率、厚度以及透射率的影响。研究表明：膜层最佳折射率在1.22左右,在此折射率条件下,保证透射率大于99%的单层增透膜的理想厚度范围应为180~220 nm,并且折射率和膜厚值的选取基本不受晶体表面小尺度波纹周期和幅值的影响。若只考虑SPDT法加工后KDP晶体表面小尺度波纹周期和幅值的实际范围,透射率基本不受波纹周期的影响,但却会随波纹幅值的增大而加速下降。理想镀膜条件下透射率最大值大于99%,并且通常在99.67%~99.94%之间。     

Synthesis and gelation behaviors of five new dimeric cholesteryl derivatives

Five new diacid amides of di-cholesteryl L-glycinates were designed and prepared.The compounds with linkers containing 0,1, 2,3,or 4 methylene units are denoted as 1,2,3,4,and 5,respectively.Their gelation behaviors in 25 solvents were tested as novel low-molecular-mass organic gelators(LMOGs).It was shown that the length of the linker connecting the two-cholesteryl residues in a gelator plays a crucial role in the gelation behavior of the compound.1 gels 11 of the 25 solvents tested at a concentration lowe...     

CHARACTERIZATIONS AND RELATIONSHIPS BETWEEN OUTDOOR AND INDOOR BIOAEROSOLS IN AN OFFICE BUILDING

1.IntroductionBioaerosolsaremicroorganismsorparticles,gases,vapors,orfragmentsofbiologicalorigin(i.e.,aliveorreleasedfromalivingorganism)thatexistintheair.Bioaerosolsareeverywhereintheenvironment.Underfavorableconditions,bioaerosolsareabletogrowandpropagateonavarietyofbuildingmaterialsandindoorsurfaces,causingindoorairpollution.Therefore,owingtotheirubiquitouspresenceinnature,bioaerosolsasapollutionsourcearealmostinevitableinarangeofenclosedenvironmentsandincommunityair(Kodama&McGee,1986;Lig…     

Synthesis and Crystal Structure of Triethyl 1,2,2-triphenylpyrrolidine-3,4,5-tricarboxylate,A Proline Derivative

１ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｒｅｃｅｎｔｙｅａｒｓ，ｏｕｒｒｅｓｅａｒｃｈｇｒｏｕｐｈａｓｓｔｕｄｉｅｄｓｙｓｔｅｍａｔｉｃａｌｙｃｙｃｌｏａｄｄｉｔｉｏｎｒｅａｃ ｔｉｏｎｓｏｆｔｈｅＣ＝Ｎｄｏｕｂｌｅｂｏｎｄｓｉｎｔｈｅｂｅｎｚｏｈｅｔｅｒｏａ...