新型高吸油性树脂材料研究进展

对高吸油性树脂的聚合工艺、吸油机理及性能指标等进行了综合评述,概述了单体配比、交联剂用量、引发剂及分散剂等影响因素对树脂吸油性能的影响,并对高吸油材料的再生和应用前景进行了展望.     

基于预编码的正交频分复用雷达通信一体化信号设计

针对正交频分复用(orthogonal frequency division multiplexing,OFDM)雷达通信一体化信号中的通信信息影响其探测性能的问题,提出一种基于预编码的OFDM雷达通信一体化信号形式.利用具有较好相关特性的伪随机序列对一体化信号的通信信息进行预编码,以提高一体化信号的模糊函数性能,进而...     

HIV preferentially infects HIV-specific CD4+ T cells

HIV infection is associated with the progressive loss of CD4(+) T cells through their destruction or decreased production. A central, yet unresolved issue of HIV disease is the mechanism for this loss, and in particular whether HIV-specific CD4(+) T cells are preferentially affected. Here we show that HIV-specific memory CD4(+) T cells in infected individuals contain more HIV viral DNA than other memory CD4(+) T cells, at all stages of HIV disease. Additionally, following viral rebound during interruption of antiretroviral therapy, the frequency of HIV viral DNA in the HIV-specific pool of memory CD4(+) T cells increases to a greater extent than in memory CD4(+) T cells of other specificities. These findings show that HIV-specific CD4(+) T cells are preferentially infected by HIV in vivo. This provides a potential mechanism to explain the loss of HIV-specific CD4(+) T-cell responses, and consequently the loss of immunological control of HIV replication. Furthermore, the phenomenon of HIV specifically infecting the very cells that respond to it adds a cautionary note to the practice of structured therapy interruption.     

伴随对及其构造

先讨论伴随对定义及其等价条件,给出伴随对存在的一个充分条件;其次讨论40个模糊蕴涵算子和40个模糊圈乘算子的性质,并给出由模糊蕴涵算子构造模糊圈乘算子的方法;最后讨论40个算子对构成伴随对的情况.     

Calcium regulation of molluscan myosin ATPase in the absence of actin

In the myosin-linked regulatory mechanism typified by the molluscan scallop adductor muscle, contraction is controlled by Ca2+ binding to sites on the thick filament protein, myosin. The regulatory light chains of myosin heads are involved directly in this mechanism and early studies suggested that, in the absence of Ca2+, these subunits prevent the interaction of a myosin-adenosine nucleotide complex with the actin-containing thin filament. Subsequently, Ashiba et al. reported that the steady-state ATPase of molluscan myosin exhibits a limited degree of Ca2+ activation in the absence of actin. Recently, however, we have shown that steady-state ATPase activity in relaxing conditions is dominated by the unregulated molecules in the myosin preparation. Single-turnover kinetic methods are required to monitor the highly suppressed ATPase activity of the regulated population. Using the latter approach, we report here that scallop myosin ATPase is reduced about 100-fold on removal of Ca2+. The regulatory light chains maintain the relaxed state via conformational changes which suppress the product release steps, irrespective of the presence of actin.     

一种基于网络图的电路状态方程列写方法

提出一种应用图论建立电路状态方程的方法，通过具体例子进一步介绍了建立图并由图得到状态方程的步骤。与其它同类方法相比，该方法更直观简捷，且无限制条件，可应用于任何电路。可看出，动态分析对于复杂电路是一种有效的方法。     

Optical properties of NdxGd1−xAl3(BO3)4 crystal

The optical properties of Nd x Gd 1-x Al\-3(BO\-3)\-4 (NGAB) crystal are reported. The refractive index of it were mesured by V_prism method. The absorption spectra and the flourescence specra of NGAB were also obtained. The optical parameters of NGAB were calculated following J_O theory, the three optical parameters are Ω 2 =1 805×10 -20 , Ω 4=1 85×10 -20 , Ω 6=3 793×10 -20 (RMS=1 4×10 -7 ) and β c( 4F 3/2 → 4I 11/2 ) is about 0 53.     

Myeloid leukaemia inhibitory factor maintains the developmental potential of embryonic stem cells

Embryonic stem (ES) cells, the totipotent outgrowths of blastocysts, can be cultured and manipulated in vitro and then returned to the embryonic environment where they develop normally and can contribute to all cell lineages. Maintenance of the stem-cell phenotype in vitro requires the presence of a feeder layer of fibroblasts or of a soluble factor, differentiation inhibitory activity (DIA) produced by a number of sources; in the absence of DIA the ES cells differentiate into a wide variety of cell types. We recently noted several similarities between partially purified DIA and a haemopoietic regulator, myeloid leukaemia inhibitory factor (LIF), a molecule which induces differentiation in M1 myeloid leukaemic cells and which we have recently purified, cloned and characterized. We demonstrate here that purified, recombinant LIF can substitute for DIA in the maintenance of totipotent ES cell lines that retain the potential to form chimaeric mice.