金融发展、法治深化与上市企业风险承担

本文从上市企业风险承担的视角,研究了中国背景下的＂法与金融＂对企业行为的影响。研究发现,地区金融发展和法治深化均与上市企业风险承担水平负相关,而两者的交互项与上市企业风险承担水平正相关。上述发现在国有企业样本中更为显著。进一步研究表明,金融发展和法治深化能够通过影响债务融资结构,进而影响企业风险承担。本文的发现揭示了＂法与金融＂的发展在中国的经济转型进程中对激励企业成长的异质性作用。In view of risk-taking of listed finns, this paper explores the impact of ＂law and finance＂ on finn behavior under China background. Our findings indicate that both financial development and legal enforcement are negatively associated with finn risk-taking, while their interaction term is positively associated with finn risk-taking. These findings are more pronounced for state-owned finns. Further analyses indicate that financial development and legal enforcement can exert influence on finn risk-taking by affecting debt structure. Our findings reveal heterogeneous impacts of the development of ＂law and finance＂ on encouraging firm growth in China＇s transition economy

Isolation of Embryo Sac Cells of Lettuce(Lactuca sativa)

用酶解和解剖方法分离了莴苣的卵细胞,助细胞,中央细胞和合子。莴苣子房先在酶液中酶解40~50MIn,然后在不含酶的分离液中用解剖针解剖子房。在解剖出的胚囊中,可看到卵细胞,两个助细胞和中央细胞的轮廓。将胚囊的合点端切破,轻轻挤压胚囊的珠孔端,四个细胞即可逸出。在最佳条件下,90MIn可从40个子房中分离出29个胚囊,进一步从中分离出11个卵细胞。分离出的胚囊细胞用显微操作仪收集备用。莴苣卵细胞的成功分离为进行离体受精探索创造了条件。Viable egg cells,synergids,central cells and zygotes of lettuce (Lactuca sativa L.) were isolated using enzymatic digestion and mechanical dissection.The ovaries were digested in enzymatic solution for 40-50 min,and then transported into the isolation solution without enzymes to dissect.In the dissected embryo sacs,the outline of an egg cell,two synergids and a central cell could be observed.When dissected embryo sacs were sliced from the chalazal end,four cells could be released by gently pushing its micropylar end.In optimal condition,29 embryo sacs and 11 egg cells could be isolated from 40 ovaries during 90 min.The isolated egg cells could be collected using micromanipulator for preparation of molecular biology of egg cell of lettuce.The isolation of egg cell of lettuce will make a great chance for in vitro fertilization in a dicot plant.国家自然科学基金(30970275

基于复合型耦合器的新型透射式GT交错复用器及色散补偿

提出了基于复合型耦合器的透射式GT腔,并将其串入马赫-曾德尔干涉仪(MZI)的两臂上,得到了一种新型的交错复用器。推导了该器件的理论表达式,并进行了数值模拟。模拟结果表明,该交错复用器具有相当好的通带平坦性,大的通带带宽、截止度和阻带带宽。对该交错复用器进行了优化分析,发现腔数固定时,纹波带宽比越大(频谱越接近矩形方波),隔离度将越小。分析结果表明,可以通过增加腔的数量来解决纹波带宽与隔离度的矛盾,即交错复用器的频谱性能随着腔数的增加得以改善。相对于环形谐振腔辅助的交错复用器,该交错复用器不需要添加额外的相移器就能获得近似矩形的频谱,并且在整个工作波段范围具有很好的频谱均匀性。对于该器件的色散问题,提出了采用级联环形腔作为色散补偿器的补偿方案。模拟结果表明,级联环形腔能够很好地补偿该交错复用器的色散

Developing fast laboratory screening platform for sulfate dioxide in food by surface-enhanced Raman spectroscopy

基于表面增强拉曼光谱(SERS)的指纹图谱的高能量分辨率,以位于~630; cm~(-1)亚硫酸根的特征峰为定性和定量依据,本文开展了食品中滥用和非法添加二氧化硫的直接检测研究:一种检测流程实现了不同食品基质中二氧化硫的; 高灵敏检测,最低检出浓度达1 mg; kg~(-1)的水平.针对实际样本的传统蒸馏法前处理流程的一些不足以及SERS检测的指纹图谱优势,本文进行了三方面显著改进:; (1)碳酸钙和沸石取代氮气以提高二氧化硫的挥发提取效率; (2)草酸取代盐酸酸化蒸馏溶液,以有效避免挥发性强酸对操作环境的危害;; (3)氢氧化钠溶液代替乙酸铅溶液作为吸收液,以防止二次污染.环境友好、灵敏度高和不受基质干扰等特点使得本方法有望取代经典蒸馏法和比色法,用于食品; 中非法添加二氧化硫类添加剂的快速高效筛查.The direct detection of sulphur dioxide has been realized in various; food matrixes with high sensitivity and high selectivity, on the basis; of the integration of the high energy resolution of the finger-print; spectrum of surface-enhanced Raman spectroscopy and the universal but; easy-on-going pretreatment procedure. The characteristic peak of sulphur; dioxide at ~630 cm~(-1) was applied as the qualitative and quantitative; standard, which displayed a lowest detectable concentration at the 1 mg; kg~(-1) level for the spiked food samples. The key point of the high; sensitivity and selectivity is the effective pretreatment born out of; the standard distillation one, which has been improved in the three; parts. (1) Using CaCO_3 and Zeolite instead of N_2 gas as the bubbling; reagent. (2) Using oxalic acid as the acidic distillation solution to; eliminate the hazards from acid volatilization, such as hydrochloric; acid. (3) Using diluted sodium hydroxide solution as the absorption; reagent instead of lead acetate solution to avoid the secondary; pollution. With the three distinguished advantages of environment; friendly, high sensitivity and free of matrix interference, the proposed; method has great potential to replace the traditional ones for the fast; screening of the illegal or abused sulphur dioxide in food.国家自然科学基金; 福建省高校产学合作项目; 中央高校基本科研业务费专项资

异三核过渡金属配合物〔Fe2Ⅲ MⅡO（OOCC2H5）6L3〕（M=Co,Ni,Mn;L=C5 H5N,H2O）溶液行为的NMR和UV谱表征

A series of new heterotrinuclear transition-metal complexes [(Fe2MO)-M-I-O-I(OOCC2H5)(6)L-3] (M = Co, Ni, Mn; L = C5H5N, H2O) were synthesized and characterized. Their structures and dynamics in different solutions and temperatures were investigated by NMR and UV. Assignments of the H-1 NMR spectra were made on the basis of relative intensities, broadening, substitution with appropriate ligands and spin-lattice relaxation. Experimental results shows that there is antiferromagnetic exchange interaction among the three metal ions within M3O core. It is found that these complexes in DMSO, CD3CN, CDl(3) and CD3COCD3 solvents are stable at room temperature and their structures in solution are the same as their crystal ones. However, the complexes decomposed into carboxylic acid, pyridin and metal ions in water. The results may be helpful in guiding synthesis of similar complexes

1978～2008年中国湿地类型变化

分别基于美国陆地卫星(Landsat MSS/TM/ETM+)和中巴资源卫星(CBERS-02B)影像数据,以人工目视解译为主,完成了中国1978～2008年4期(基准年分别为1978,1990,2000和2008年)湿地遥感制图,并进行了大量的室内外验证.在此基础上,对我国湿地现状及近30年来湿地变化进行了初步分析,得到以下主要结论:(ⅰ)截止2008年,中国湿地面积约为324097km2,其中以内陆沼泽(35%)和湖泊湿地(26%)为主.(ⅱ)1978～2008年,中国湿地面积减少了约33%,而人工湿地增加了约122%.过去30年里湿地减少的速度大幅降低,由最初5523km2/a(1978～1990年)降为831km2/a(2000～2008年).(ⅲ)减少的自然湿地(包括滨海湿地和内陆湿地),其类型变化由湿地向非湿地转化的比例逐渐降低.初期(1978～1990年)几乎全部(98%)转换为非湿地;在1990～2000年间减少的自然湿地约有86%转化为非湿地,而在2000～2008年,这一比例下降为77%.(ⅳ)气候变化和农业活动是中国湿地变化的主要驱动因素,湿地变化在中国分为三大不同特征区域,即西部三省/自治区(西藏、新疆和青海)、北部两省/自治区(黑龙江和内蒙古)和其他省市区.其中西部区域尤其是青藏高原,湿地变化的驱动因子以气候增温为主;新疆湿地由于气候增温和农业活动共同作用造成变化不大.北部省/自治区的湿地变化则主要由农业活动引起;而其他省市区的湿地变化几乎完全受控于人类的农业经济活动