陕西咸阳人工林地土壤干层研究

IEECAS SKLLQG

束流调制器物理机制与电子学设计

兰州重离子回旋加速器装置H IRFL在某种工作模式下,需要对束流在时间上进行调制,以避免束流对输运线造成损伤;并在加速器引出的束流能量较高且流强很大时,采用束流调制器可使调束在较低的流强下进行,而不必改变加速器的参数。调制器由加装在束运管道上的两个平行电极与相应的电子学电路组成。为满足调制脉冲前后沿的时间要求,电子学设计着重考虑展宽电压放大器频带低品质因数电路设计。

大兴安岭呼中林区火烧迹地粗木质残体特征

对大兴安岭呼中林区不同年份火烧迹地的粗木质残体特征进行了研究.结果表明:呼中林区火烧迹地粗木质残体贮量在24.87～180.98m3.hm-2,其中倒木和枯立木分别为6.03～93.91m3.hm-2和15.29～138.37m3.hm-2,且不同年份火烧迹地之间差异显著;倒木、枯立木所占比例分别为24.26%～86.00%和14.01%～75.4%,且不同年份火烧迹地之间差异显著;倒木和枯立木的优势径级分别为2.50～20cm和1.50～15m,优势长度分别为2.50～15cm和5～20m;随着火烧迹地的恢复,粗木质残体贮量的动态变化不明显.粗木质残体特征与火前林分条件和火烧强度密切相关.

Magnetic microsphere and its use in biochemical separation and analysis

Magnetic microsphere comprises a magnetically responsive metal or metal oxide core surrounded by a polymer shell with active groups. Nowadays, methods of directly coating polymer, monomer polymerazation, impregnation, extrusion and biological synthesis are generally used to prepare magnetic particles. This kind of superparamagnetic microspheres can be attached to chemical, biochemical and biological substances by their active groups, then applying a magnetic field to separate from the media. Preparation and utilization of magnetic microspheres in immunoassay, nucleic acid hybrization assay, gene sequencing, cell isolation, enzyme immoblization, receptor isolation and other Gelds are reviewed with 44 references in this paper. Also, the further development is outlooked.

磁微球及其在生化分离分析中的应用

磁微球是以金属或金属氧化物为核,外面包被带有活性基团物质的一种新型生物分离材料.目前制备磁微球的方法有包埋法、聚合法、浸渍法、挤压法和生物合成法等.这种微球通过其活性基团与化学、生化和生物物质连接后,利用其顺磁性外加一定磁场可实现与介质分离.本文全面地介绍了磁微球的制备,详尽评述了其在免疫分析、核酸杂交分析、基因测序、细胞分离、酶的固定、受体分离等各个领域的应用.

Analysis of tandem repeats in the genome of Chinese shrimp Fenneropenaeus chinensis

Through random sequencing, we found a total of 884000 base-pairs (bp) of random genomic sequences in the genome of Chinese shrimp (Fenneropenaeus chinensis). Using bio-soft Tandem Repeat Finder (TRF) software, 2159 tandem repeats were found, in which there were 1714 microsatellites and 445 minisatellites, accounting for 79.4% and 20.6% of repeat sequences, respectively. The cumulative length of repeat sequences was found to be 116685 bp, accounting for 13.2% of the total DNA sequence; the cumulative length of microsatellites occupied 9.78% of the total DNA sequence, and that of minisatellites occupied 3.42%. In decreasing order, the 20 most abundant repeat sequence classes were as follows: AT (557), AC (471), AG (274), AAT (92), A (56), AAG (28), ATC (27), ATAG (27), AGG (18), ACT (15), C (11), AAC (11), ACAT (11), CAGA (10), AGAA (9), AGGG (7), CAAA (7), CGCA (6), ATAA (6), AGAGAA (6). Dinucleotide repeats, not only in the aspect of the number, but also in cumulative length, were the preponderant repeat type. There were few classes and low copy numbers of repeat units of the pentanucleotide repeat type, which included only three classes: AGAGA, GAGGC and AAAGA. The classes and copy numbers of heptanucleotide, eleven-nucleotide and thirteen-nucleotide primer-number-composed repeats were distinctly less than that of repeat types beside them.

两种红树林植物海漆和海桑化学成分研究

本论文对两种红树林植物海漆 (Excoecaria agallocha L.) 和海桑（Sonneratia caseolaris L.）的化学成分进行了系统研究。 采用常规的硅胶柱层析、制备薄层层析、凝胶 Sephadex LH-20 柱层析、MCI柱层析、反相硅胶柱层析、半制备型 HPLC 以及重结晶等手段，从海漆 (Excoecaria agalloch L. ) 中分离得到 40 个化合物，从海桑（Sonneratia caseolaris L.）中分离得到 30 个化合物。利用各种现代波谱技术 (IR、UV、ESI-MS、EI-MS、1D-NMR、2D-NMR等) 及其化学物理性质，确定了海漆中 32 个化合物的结构，其中包括 1 个新的三萜天然产物以及 15 个首次从海漆中报道的化合物；确定了海桑中 27 个化合物的结构，其中包括 1 个新化合物和一个首次报道其碳谱数据的化合物。本文为首次报道海桑的化学成分研究。 对海漆和海桑粗提物及分离得到的部分化合物进行了抗肝癌细胞毒活性筛选，化合物S22表现出较强活性，其IC50为2.8 μg/mL；海漆和海桑粗提物及其它部分单体化合物只表现出微弱活性；阳性对照丝裂霉素C的IC50为1.1 μg/mL。 对分离得到的部分样品还进行了抗菌活性测试，各样品在测试浓度下对测试菌均未表现出明显的抗菌活性。 首次研究了海漆挥发性成分及其季节性变化。利用水蒸汽法提取了不同季节海漆的挥发性成分，通过GC-MS鉴定其化学组成，发现脂肪酸、二萜和倍半萜是海漆挥发性成分的主要组成，不同季节的挥发性成分差异较大。

大黄属植物地上部分蒽醌类物质的提取工艺

本发明涉及一种利用大黄属植物地上部分提取蒽醌类物质的工艺，该工艺设备简便、溶剂低廉、可回收重复利用，工艺提取效率高，所得提取液安全、纯度高。

压力和铁含量对铁方镁石(Mg1-xFex)O(x<=0.25)弹性常数影响的第一性原理研究

By first principle methods based on density functional theory (DFT),the equation of state(EOS) and elastic constants of both periclase and ferropericlase are calculated. The pressure and iron doping effects on the elastic constants of ferropericlase are investigated systematically. Firstly, we calculate the elastic constants of periclase and compare the obtained results with experimental data and other theoretical calculations, which shows a encouraging consistence and demonstrates the practicability of first-principle methods. Secondly, by adding iron into periclase crystal model, we build up ferropericlase with iron contents ranging from 0% to 25% mole percent. The corresponding elastic constants are calculated in a large pressure range(0~120GPa). Emphatically, the strong correlation of 3d electrons in transitional elements, such as iron, is difficult to treat in first-principle methods for a long time. The current solution is to make additional correction. During the initial stage of this study, the strong correlation of 3d electrons in iron is not considered, and we observed that addition of iron decreases the volume of ferropericlase, which is totally contradictory to the experimental data. By applying LDA+U approximation in order to solve the strongly correlated 3d electron of iron, we observed the expansion of volume by iron as expected. On the basis of the LDA+U approximation, the elastic constants of ferropericlase are calculated. After a detailed analysis of data obtained from theoretical calculations, we have reached the following conclusions:(1)pressure imposes positive effects on all elastic constants, and the degree of effects is C11>C12>C44. (2) Iron has no distinctive effects on C11 and C12, although some fluctuations are observed around 60GPa. However, iron has obvious softening effects on C44 The softening effects on C44 are intensified as pressure increases. Above the 100GPa, the effects increase greatly, even surpasses the pressure's positive effects in ferropericlase crystal models with iron mole percent of having 12.5%, 18.75% and 25% iron content. (3)As to the modulus deprived from elastic constants, iron has no effect on the adiabatic bulk module BS, only a little fluctuation around 60GPa. We find iron's softening effects on shear modulus G. (4)We find out that, compared with low iron content, elastic constants with iron content approaching 25mole% is consistently fluctuated，which may be caused by the limitations of the LDA+U approximation method itself. (5)We investigate the pressure and Fe doping effects on elastic anisotropy factor（A=(2C44+C12-C11)/C11） of ferropericlase and find out that iron contents will lower the critical isotropic pressure. At the same pressure, when the pressure is below the isotropic pressure, iron softens the anisotropy factor ; when pressure surpasses the isotropic pressure, iron increases the anisotropy factor.