Frequency synthesizer of short-wave SFH/MFSK system

The technology of DDS-driven PLL is introduced and a new scheme of frequency synthesizer which is suitable for SW SFH/MFSK System is presented in this paper. Based on the special requirement of SW communication, a model of the scheme is given and the results show that the frequency synthesizer has small frequency insteval (≤0.1 Hz), short switch pierod (<200 ms) and high frequency stability as crystal oseillator. Supported by the National Nature Science Foundation of China and the Advanced Research Foundation of National Defence Gan Liangcai: born in 1941, Professor     

Role of PHABULOSA and PHAVOLUTA in determining radial patterning in shoots

The upper side of the angiosperm leaf is specialized for efficient capture of sunlight whereas the lower side is specialized for gas exchange. In Arabidopsis, the establishment of polarity in the leaf probably requires the generation and perception of positional information along the radial (adaxial versus abaxial or central versus peripheral) dimension of the plant. This is because the future upper (adaxial) side of the leaf develops from cells closer to the centre of the shoot, whereas the future under (abaxial) side develops from cells located more peripherally. Here we implicate the Arabidopsis PHABULOSA and PHAVOLUTA genes in the perception of radial positional information in the leaf primordium. Dominant phabulosa (phb) and phavoluta (phv) mutations cause a dramatic transformation of abaxial leaf fates into adaxial leaf fates. They do so by altering the predicted sterol/lipid-binding domains of ATHB14 and ATHB9, proteins of previously unknown function that also contain DNA-binding motifs. This change probably renders the protein constitutively active, implicating this domain as a central regulator of protein function and the PHB and PHV proteins as receptors for an adaxializing signal.     

同向双螺杆挤出熔融理论研究中对啮合区的处理

对啮合区的处理是同向双螺杆挤出理论研究中的难点之一。采用能量法计算啮合区对熔融过程的影响,并将这一影响引入熔融过程的非啮合区理论模型中,获得了比较接近实测数据的计算结果。     

Shor整数分解量子算法的加速实现

基于半经典量子Fourier变换的实现方法,提出了整数k的3元二进制表示生成向量和生成函数概念,构造了生成函数的真值表,证明了由其逐比特生成的整数k的3元二进制表示向量是整数k的一种NAF表示,且表示中非0元个数的最大值为[(「logk■+1)2],并基于此重新设计了Shor算法的量子实现线路.与Parker的Shor算法量子实现线路相比,计算资源大体相同(所需的基本量子门数量均为O(「logN■3),所需的量子比特数量前者较后者多2量子比特),但实现速度提高了2倍.     

负载AlCl3于离子交换树脂固体超强酸催化剂的研制

研制了一种在磺酸型阳离子交换树脂上负载ＡｌＣｌ３的固体超强酸催化剂,以产品的含铝量作为检验指标,研究了反应温度、时间及不同种类阳离子树脂的对负载ＡｌＣｌ３量的影响,研制出一种含Ａｌ１．４０％的固体超强酸催化剂。     

线粒体参与了三尖杉酯碱诱导的HL-60细胞凋亡

用流式光度术研究了三尖杉酯碱诱导人早幼粒白血病ＨＬ－６０细胞及其转染了ｂｃｌ－２基因的细胞株ＨＬ－６０／Ｂｃｌ－２线粒体膜电势的变化,数据表明线粒体损伤介导了ＨＴ诱导的ＨＬ－６０细胞的凋亡过程。     

柘林湾赤潮与Fe、Mn、Se和营养盐指数的关系

１９９７年底广东省柘林湾发生褐囊藻（Ｐｈａｅｏｃｙｓｔｉｓ ｐｏｕｃｈｅｔｉｉ）赤潮期间,水体、沉积物和赤潮生物中Ｆｅ、Ｍｎ的质量含量很高。借且叶绿素ａ与海洋初级生产力呈正相关性,探讨了褐囊藻赤潮与Ｆｅ、Ｍｎ、Ｓｅ的质量浓度和营养盐综合指数的关系。     

ATR/ATM-mediated phosphorylation of human Rad17 is required for genotoxic stress responses.

Genotoxic stress triggers the activation of checkpoints that delay cell-cycle progression to allow for DNA repair. Studies in fission yeast implicate members of the Rad family of checkpoint proteins, which includes Rad17, Rad1, Rad9 and Hus1, as key early-response elements during the activation of both the DNA damage and replication checkpoints. Here we demonstrate a direct regulatory linkage between the human Rad17 homologue (hRad17) and the checkpoint kinases, ATM and ATR. Treatment of human cells with genotoxic agents induced ATM/ATR-dependent phosphorylation of hRad17 at Ser 635 and Ser 645. Overexpression of a hRad17 mutant (hRad17AA) bearing Ala substitutions at both phosphorylation sites abrogated the DNA-damage-induced G2 checkpoint, and sensitized human fibroblasts to genotoxic stress. In contrast to wild-type hRad17, the hRad17AA mutant showed no ionizing-radiation-inducible association with hRad1, a component of the hRad1-hRad9-hHus1 checkpoint complex. These findings demonstrate that ATR/ATM-dependent phosphorylation of hRad17 is a critical early event during checkpoint signalling in DNA-damaged cells.     

小麦谷蛋白亚基与品质的关系

小麦的品质分营养品质和加工品质,其中,加工品质的好坏是小麦品质好坏的最重要指标之一。国内外自1979年至今,对品质的研究发现,5＋10谷蛋白亚基是影响小麦加工品质的主要因素。国内对其研究的深入以及杂交时配合力对其的影响和低分子量谷蛋白亚基对品质的影响构成了我国目前小麦品质育种和品质改良的理论基础。     

聚甘氨酸修饰碳纤维微电极差示脉冲伏安法测定尿酸

研究聚甘氨酸修饰碳纤维微电极（CFME）的电化学性质和在抗坏血酸存在下测定尿酸的分析方法,以及尿酸在聚合膜电极上反应的动力学参数。在选定的条件下,尿酸和抗坏血酸的峰电位分别为0.33V和0.03V,两峰电位差达300mV,可以有效地避免抗坏血酸对尿酸测定的干扰。该方法可用于实际尿样中尿酸的测定。