固体样品进样技术中汞量定标方法的研究

在原子吸收光谱分析中,固体样品直接进样是目前的研究课题之一。本文主要报道作者在分析汞中所进行的固体直接进样技术工作和讨论。在我们研制成功的KT—81型塞曼效应测汞仪中,针对元素汞蒸气压高的特点,用饱和汞蒸气作为汞量标准,实现了固体样品,如土壤、污泥、毛发、煤、食品等汞含量的直接进样测定。汞蒸气一次制备后可长期使用。分析汞时,只要用标准气体任意校验一次就可测量。1～2分钟能分析一个样品,S<0.3ng。r<5%。此法用NBS标准物质验证过。     

Effective potential for local composite operators and the problem of factorization of multi-field condensates

A new formulation of effective potential for local composite operators is given. The two-fermion condensate \(\langle \bar \Psi \Psi \rangle \) and four-fermion condensate \(\langle \bar \Psi \Psi \bar \Psi \Psi \rangle \) are calculated simultaneously in the Gross-Neveu model up to next-to-the-leading order in 1/N expansion. It is shown that factorization \(\langle \bar \Psi \Psi \bar \Psi \Psi \rangle = C_1 \langle \bar \Psi \Psi \rangle ^2 \) holds only in theN→∞ limit and the non-factorized part of \(\langle \bar \Psi \Psi \bar \Psi \Psi \rangle \) contributed by the order-1/N terms is comparable to \(C_1 \langle \bar \Psi \Psi \rangle ^2 \) when takingN=3.     

滚动轴承疲劳故障的在线监视和诊断技术

本文研究振动诊断方法在滚动轴承疲劳故障在线监视和诊断中的应用。 文中指出:通过在轴承寿命试验机上所作的大量试验发现,当轴承疲劳后,在作为其二次效应的振动信号中,除存在已为国内外学者指出并广为使用的“通过频率(又称冲击振动发生间隔频率)”和“高频冲击脉冲”两种信息特征外,还存在另一种位于中高频段的鲜为人知的重要信息特征——某“高频峰群”。 本文对该高频峰群的形成机理、影响因素及检测方法进行了初步研究,并利用这种新的信息特征研制了“以带通滤波器或以精化信息特征DDS模型谱分析法为主体的两种轴承疲劳故障在线监视和诊断装置。     

Exponential approximations in the classes of life distributions

In this paper we discuss the approximation of life distributions by exponential ones. The main results are: (1) F NBUE, where its mean is 1, we have , 0, where = 1 - ₂/2, ₂ being the second moment ofF. The inequality is sharp. (2) In the case ofFIFR, the upper bound is . (3) For the HNBUE class, the upper bound is min . Furthermore, the improved upper bound is . In addition, we show 0} |\bar G(t) - e^{ - t} | \leqslant \sqrt {\frac{\rho }{2}} $$ " align="middle" border="0"> , where (4) For the IMRL class, the upper bound is /(1+) ([1]). Here we give a simple proof.Project supported by the National Natural Science Fund of China.     

Determination of the partial electron capture- and spontaneous-fission half-lives of254No

The isotope²⁵⁴No was produced in the fusion reaction⁴⁸Ca +²⁰⁸Pb. Using the velocity filter SHIP and radiochemical techniques it was found that the nuclide²⁵⁴No with a half-life of 55 s decays byα, EC, and spontaneous-fission. Deduced partial half-lives are (61±2) s forα-decay, (550 _?160 ⁺³⁷⁰ ) s for EC and [2.2 _?1.0 ^+2.0 ]×10⁴ s for spontaneous fission.     

由肉桂酸生物合成L-苯丙氨酸

本文评述了Ｌ－苯丙氮酸的各种合成路线、国内外的研究现状及工业化情况，重点讨论了由肉桂酸和氨生物合成Ｌ－苯丙氨酸的路线，提出了在国内进一步工作的建议。     

平辊薄件轧制的刚塑性有限元计算

本文用钢塑性有限元方法,对平辊同步和异步薄件轧制进行了计算,求出力能参数、速度场和应力应变场,并对二者加以比较。之后,又对异步轧制的特征进行了分析。     

聚合物电致发光材料研究进展

本文较详细地综述了聚合物电致发光材料的研究进展，重点介绍了聚对苯撑乙烯（ＰＰＶ），并提出了有关聚合物电致发光材料及器件构造研究的一些观点。