402 resultados para 1266


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IEECAS SKLLQG

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The hydroconversion of n-paraffins is a key reaction in hydrodewaxing of lubricating base oil. In this paper, we investigate the performance of Pt/SAPO-11 catalysts for isomerization of n-paraffins by the model compound of n-dodecane. Under this experimental condition, yields of feed isomers as well as cracking products are a function of the total n-dodecane conversion. Primary products are methylundecane while multi-brancheds and cracking products are formed in successive reactions. The result shows that the addition of Sn increases the selectivity for isomerization reaction. The most ideal experimental data for hydroconversion of n-dodecane is that the selectivity of isomerized products gets 90% when conversion of n-dodecane is 90% for the Sn-promoted Pt/SAPO-11 catalyst.

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本文以生态经济学理论为基础,以农业经济学、资源经济学、环境经济学、决策学的基本原理为指导,从实事求是的科学态度出发,]以大量的事实为依据,从系统的观点,动态的角度分析了农业可持续发展的起源、经验教训、发展的必然性,结合国外农业的研究探讨了农业可持续发展的涵义、目标、不同观点及产生背景,研究了农业可持续发展的作用及意义。

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以牛血清白蛋白(BSA)为模型药物,研究了一种新型载药微球的水包油包固体(S/O/W)乳化法.用纳米尺寸的SiO2吸附溶液中的BSA,得到粒径约为30nm的含药粒子,再用PLGA包裹含药粒子.考察不同制备条件对载药量和包封率的影响,并与传统的双乳法(W/O/W)进行了对比,发现该制备方法提高了药物的载药量(由2.5%到3.1%)和包封率(由72%到90%以上),同时提高了药物活性.

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The crystal structures of EtEDTB.1.4C(2)H(5)OH.5H(2)O 1 and H4EtEDTB(ClO4)(4).C2H5OH 2 (EtEDTB = N, N,N',N'-tetrakis[2-(1-ethylbenzimidazolyl)methyl]-1,2-ethanediamine) have been determined by single-crystal X-ray diffraction method. Compound 1 crystallizes in the space group P(1) over bar with a = 11.489(2), b = 11.866(3), c = 12.002(3) Angstrom, alpha = 97.47(2), beta = 114.564(13), gamma = 114.11(2)degrees, V = 1266.6(5) Angstrom(3), Z = 1, M-r = 847.48, D-c = 1.111 g/cm(3), F(000) = 456 and mu(MoKalpha) = 0.076 mm(-1). A total of 5207 reflections were measured for 1, of which 4323 were independent. The structure of 1 was solved by direct methods and refined by full-matrix least-squares technique to the final R = 0.0706 and wR = 0.1802 for 1318 observed reflections with I > 2sigma(I). In the structure of 1, centrosymmetric EtEDTB molecules are linked by hydrogen bonds through water and ethanol to form 2-dimensional network. Compound 2 crystallizes in the space group C2/c with a = 24.260(5), b = 13.040(3), c = 17.680(4) Angstrom, beta = 97.50(3)degrees, V = 5545.2(2) Angstrom(3), Z = 4, M-r = 1140.80, D-c = 1.366 g/cm(3), F(000) = 2384 and mu(MoKalpha) = 0.289 mm(-1).

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研究了在盐酸介质中 NO2与中性红的亚硝化反应。结果表明,在0.048mol/L的盐 酸介质中,NO2与中性红反应生成无荧光的物质,NO2在40-240 μg/L范围内与荧光猝灭程 度成正比,常见的共存离子不干扰其测定。所拟方法用于水样中NO2的测定,结果满意。

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有机锡化合物被广泛用作塑料制品中的稳定剂、船舶油漆的防污剂、工业催化剂、农林业杀虫杀菌剂以及用于木材的防腐保存等,已经引起严重的环境污染。世界上许多国家纷纷制定相应的法规对其使用加以禁止或限制。我国目前还没有明确的限制有机锡使用的法律法规,缺少有机锡污染的第一手资料,更没有长期的控制、监测与研究计划。由于有机锡的种类繁多,理化性质存在差别,所以在提取、分离和测定中均存在较大的困难。从我国这方面己有的工作来看,缺乏各种高选择性的分离方法和高灵敏度的检测方法是制约这项研究广泛开展的原因之一。有机锡的痕量与超痕量分析技术是当今环境和食品安全分析领域的前沿技术。 本论文利用高效液相色谱和电感耦合等离子体质谱联用技术建立了海洋环境中多种有机化合物的同时快速检测方法;发展了多种海洋环境样品中有机锡的前处理技术;研究了有机锡在海洋生物中的分布、代谢及降解过程中化学形态的变化;同时发展了海洋环境中多种痕量元素的快速检测方法。所建立的高效液相色谱和电感耦合等离子体质谱联用技术可同时、快速分析5种有机锡的形态(三甲基锡TMT、二苯基锡DPhT、二丁基锡DBT、三丁基锡TBT和三苯基锡TPhT),其检出限均低于0.3μg/L。 用所建立方法对南海海洋生物样品中的有机锡污染进行了研究,利用SPSS软件对检测结果进行了探讨,发现在所研究海洋生物样品的97.2%中可检出丁基锡和苯基锡化合物,其浓度分布处于该化合物检出限~1487.8ng/g范围内。其中,贝类样品中总有机锡的平均浓度为416.9ng/g,远远高于鱼类样品中总有机锡的平均浓度(211.9ng/g)。海洋生物中存在高浓度的有机锡说明本海域有机锡污染严重,已经对生态环境造成了严重影响,危害到人类生活。其主要的污染源是防污涂料的应用,目前紧迫的问题是采取必要的措施来控制有机锡的使用。 本工作建立了海水样品和沉积物样品中五种有机锡的简单快速萃取方法。采用加入2%的环庚三烯酚(tropolone)的二氯甲烷CH2Cl2对海水中的有机锡进行萃取,大大提高了有机锡的萃取率,减少了萃取的时间,二苯基锡(DPhT)、二丁基锡(DBT)、三丁基锡(TBT)和三苯基锡(TPhT)的萃取率均在80%以上,仅三甲基锡(TMT)的萃取率较低(在50%左右),究其原因,可能是因为在萃取的过程中三甲基锡(TMT)产生了降解。采用流动相和0.2%环庚三烯酚酮(tropolone)对沉积物国际标准物质PACS-2进行超声萃取及高速离心后,用所建方法进行了分析。结果表明,测定值与标准值吻合。研究表明,所建立的方法可用于实际环境沉积物中有机锡的形态分析。 本文建立了流动注射与电感耦合等离子体质谱联用技术直接同时测定海水中多种痕量元素的方法。该方法采用痕量进样技术,能够有效地减少海水中Na,Mg, Ca和Cl等大量基体元素对待测痕量元素测定的干扰,减少这些元素在电感耦合等离子体采样锥上的盐沉积,可以同时测量海水中的V、Cr、Mn、Fe、Co、Ni、Cu、Zn、As、Mo、Cd、Pb,Hg和U等痕量级元素。用所建的方法测定南海海域海水中的重金属元素,发现Cd,Cr,As等有毒有害元素的污染很轻,均符合Ⅰ级海水的限量。 在海洋沉积物样品处理研究中,本工作改进了不需要赶走HF酸就可以对沉积物消解完全的密闭容器消解法,由于减少了赶走HF酸的步骤,使消解的时间由原来的二十个小时降低为十个小时,大大降低了消解的时间。采用该样品消解方法,并用ICP-MS测定了南黄海海域沉积物中锡及其他重金属元素的含量。建立了微波消解-ICP-MS测定海洋生物中锡、砷、镉、汞及铅等有害重金属元素的分析方法,并用于南黄海7个及南海海域29个海产品中的测定。测定结果表明海洋生物中上述有毒有害元素有不同程度的超标问题;不同种类,不同产地的海洋生物中重金属元素的含量有一定的差别,这些研究结果为海产品安全质量控制提供了有价值的科学信息。 在上述各章工作的基础上,本文研究了有机锡在海洋生物中的分布、代谢及降解过程,并初步建立了高效液相-电喷雾-飞行时间质谱(LC-APCI-TOF-MS)测定有机锡的方法,可对未知的有机锡化合物进行结构表征。有机锡在贝类中不同的组织显示,其内脏中有机锡的含量高于肌肉中有机锡含量。常规的煮、炸、蒸及微波的烹饪方式并不能降解海产品中的有机锡化合物。

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Five minor sesquiterpenes (1-5) with two novel carbon skeletons, together with a minor new oplopane sesquiterpene ( 6), have been isolated from the brown alga Dictyopteris divaricata. By means of spectroscopic data including IR, HRMS, 1D and 2D NMR, and CD, their structures including absolute configurations were assigned as (+)-(1R, 5S, 6S, 9R)3- acetyl-1-hydroxy-6-isopropyl-9-methylbicyclo[4.3.0] non-3-ene ( 1), (+)-(1R, 3S, 4S, 5R, 6S, 9R)-3-acetyl-1,4-dihydroxy-6- isopropyl-9-methylbicyclo[4.3.0] nonane (2), (+)-(1R, 3R, 4R, 5R, 6S, 9R)-3-acetyl-1,4-dihydroxy-6-isopropyl-9-methylbicyclo[ ;4.3.0] nonane ( 3), (+)-(1S, 2R, 6S, 9R)-1-hydroxy-2-(1-hydroxyethyl)-6-isopropyl-9-methylbicyclo[4.3.0] non-4-en-3-one (4), (-)-( 5S, 6R, 9S)-2-acetyl-5-hydroxy-6-isopropyl-9-methylbicyclo[4.3.0] non-1-en-3-one ( 5), and (-)-( 1S, 6S, 9R)- 4-acetyl- 1-hydroxy-6-isopropyl-9-methylbicyclo[ 4.3.0] non-4-en-3-one ( 6). Biogenetically, the carbon skeletons of 1-6 may be derived from the co-occurring cadinane skeleton by different ring contraction rearrangements. Compounds 1-6 were inactive (IC50 > 10 mu g/mL) against several human cancer cell lines.

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Grazing animal excrement plays an important role in nutrient cycling and redistribution in grazing ecosystems, due to grazing in large areas and return in small areas. To elucidate the changes to the soil and pasture caused by sheep urine, fresh dung, and compost patches, a short- term field experiment using artificially placed pats was set up in the autumn of 2003 in the Inner Mongolian steppe. Urine application significantly increased soil pH during the first 32 days in soil layers at depths of both 0 - 5 cm and 5 - 15 cm. Rapid hydrolysis of urea gave large amounts of urine- nitrogen ( N) as ammonium ( NH4+) in soil extracts and was followed by apparent nitrification from day 2. Higher inorganic N content in the urine- treated soil was found throughout the experiment compared with the control. No significant effects of sheep excrement on soil microbial carbon ( C) and soil microbial N was found, but microbial activities significantly increased compared with the control after application of sheep excrement. Forty- six percent of dung- N and 27% of compost- N were transferred into vegetation after the experiment. The results from this study suggest that large amounts of nutrients have been lost from the returned excrement patches in the degraded grassland of Inner Mongolia, especially from sheep urine- N.

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提出一种用水平导轨上 4个滑块作为原动件的混合型 4自由度并联平台机构 ,该机构的动平台能够实现 2个方向的移动以及绕 2个方向轴线的转动。研究了该机构的运动学建模方法 ,给出了运动学正逆解 ,并阐述了其应用前景

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The most widespread rock associations in the Western Block of North China Craton are khondalites distributed mainly in Jining, Liangcheng and Datong. A large quantitiy of garnet-bearing granites are contained in the khondalites. A great deal of research has been carried out on them by previous researchers. Studies of these garnet-bearing granites consist essentially of structural characteristics, petrography and geochemistry, and finally geochronological determinations. Summing up these researches, it will not be difficult to see that all of these authors have regarded these large numbers of garnets (up to 20%) contained in granites as crystallized products from magmas, but they have not proved this from petrological perspective. Theoretically, there are possibly three kinds of petrogenesis as to these garnets. The first one is that they have been transferred to the granites from khondalites by melt when anatexis happened to khondalites, and they, in essence, are residual metamorphic garnets; The second one is that when the khondalites were being melted, these garnets were produced from biotite dehydration melting, and the newly formed garnets intruded together with the melt and eventually molded the garnet-bearing granites. Garnets of this possible kind either showed independent crystals, or garnets from khondalites took place secondary growth under favorable temperature and pressure conditions for their crystallization; The last possibility is that these garnets were crystallized from magmas in which suitable pressure, temperature and composition were available. These garnets, generally, should be fine-grained. The aim of this study is, through examining the mineral chemistry of the garnets and the whole rock chemistry, to ascertain under which kind of mechanism, in the world, did these garnets form? Besides, we try to calculate the temperatures under which khondalites began melting and reactions of the garnets and the cooled melts happened by garnet-biotite thermometry. The whole rock chemistry analyses of the garnet-bearing granites tell us that all the samples are strongly peraluminous (A/CNK greater than 1.1) on the A/NK vs. A/CNK plot. On the SiO2-K2O plot, the granites are mainly constrained to be high-K calc-alkaline and calc-alkaline series, consistent with previous researches. On the ACF((Al2O3-Na2O-K2O)-FeO(T)-CaO) discrimination plot, all the six garnet-bearing granite samples drop into the area of S-type granites. The relationship between CaO/Na2O and SiO2 shows that the overwhelming majority of garnet-bearing granites have a CaO/Na2O value over 0.3, revealing that they probably come from metagreywacke precursors or mediate-felsic orthogeneisses compositionally similar to them. Detailed EPMA analyses conducted on the garnets contained in the garnet-bearing granites show that all the garnets are dominated by almandine and pyrope, which occupy 92-96% (Weight Percentage) of each garnet analyzed, typical of granulite facies. Their chemical composition is entirely different from those crystallized in magmas, but extremely similar to those of typical granulite facies metapelites in khondalites and typical granulites, indicating all the garnets to be metamorphogenic. In addition, REEs distribution patterns of the garnets are totally different from typical biotite granites and peraluminous granites. In other words, both LREE and HREE of our garnets are evidently lower than those from these two kinds of rocks. Moreover, compared to the REE pattern of the garnets from typical amphibolites, LREE content of our garnets is obviously higher and HREE content is a little lower. However, REE patterns of our garnets are completely in harmony with those of garnets from typical granulites. So, the REE patterns of garnets, again, prove that all the garnets we studied are metamorphogenic. Biotites appear in two forms, being as inclusions in the garnet and as selvages immediately adjacent to the garnet, respectively. Two reactions and their corresponding temperatures, with the help of petrography and Garnet-Biotite geothermometers, could be obtained, which are Bt+ Pl+ Qtz→Kfs+ Opx+ Grt+ melt as positive reaction and Kfs+ Grt+ melt→Bt+ Pl+ Qtz as reverse reaction, respectively. Summing up the discussion above, we declare that the garnet-bearing granites distributed in the Western Block of North China Craton are the mixture of melts and restites resulted from biotite dehydration melting. The garnets contained in the restites are the products from biotite dehydration melting and restites from the khondalites, respectively.

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Jones, David, '?The Lord did give me a particular honour to make [me] a peacemaker?: Howel Harris, John Wesley and Methodist infighting, 1739-1750', Bulletin of the John Rylands, University Library of Manchester (2003) 85(2-3) pp.73-88 RAE2008