159 resultados para 341.2422
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用电子束加热沉积法(EBD)制备了厚度420um的ZnIn2ZTe4薄膜。研究了最佳成膜工艺条件和性能,用电子能谱(XPS)分析了ZuIn2Te4薄膜的组成、结构和状态;典型ZnIn2Te4膜最佳参数为:电阻率ρ为3.2×10-1Ω·cm,Hall迁移率是79cm2V-1s-1,载流子浓度是1.58×1017cm-3,禁带宽度(Eg)是2.33eV;探讨了ZuIn2Te4膜导电机理,制作了ZuIn2Te4-Si太阳能电池。
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测定了酸性水溶液中甘氨酸、丝氨酸和天冬氨酸稀土络合物(Ln=La、Pr、Nd、Eu、Tb、Dy、Ho、Er、Tm和Yb)的~(13)C诱导位移。对位移试剂的分析指出,三种氨基酸通过α-羧基以双齿形式配位于稀土,配位键长为0.23nm~0.25nm,天冬氨酸的y-羧基也是配位基团。由本文与文献中已报道的各种氨基酸稀土络合物的~(13)C诱导位移的系统分析表明,配体~(13)C超精细偶合常数A值和结构因子G值有如下规律:(1)│A(C_0)│<│A(C_α)│;A(C_0)为正,A(C_α)为负;(2)│G(C_0)│>│G(C_α)│;配体碳核的G均为负值。
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结合膜的形态结构研究了以 LiCl为添加剂制得的疏水 PVDF膜的膜蒸馏性能。与来用水溶液高分子添加剂制得的PVDF微孔膜相比,膜蒸馏性能有了较大提高,尤其具有更高的截留率。制得的微孔膜的蒸馏通量已接近商品膜的膜蒸馏通量,表明以LiCl为添加剂制得的PVDF疏水微孔膜是一种适用于膜蒸馏的较理想的疏水微孔膜。
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介绍了p-n结电容测量方法。通过测量C-V特性研究了Cds太阳电池的热处理及上栅过程,分析并讨论了p-n结的变化与电池不稳定的关系。初步研究了扩散电位的测定问题。
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Matrix-bound phosphine was determined in the Jiaozhou Bay coastal sediment, in prawn-pond bottom soil, in the eutrophic lake Wulonglan, in the sewage sludge and in paddy soil as well. Results showed that matrix-bound phosphine levels in freshwater and coastal sediment, as well as in sewage sludge, are significantly higher than that in paddy soil. The correlation between matrix bound phosphine concentrations and organic phosphorus contents in sediment samples is discussed.
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Three new bromophenols C-N coupled with nucleoside base derivatives (1-3) and three new brominated 1,2,3,4-tetrahydroisoquinolines (5-7, together with a new brominated tyrosine derivative (4, have been isolated from polar fractions of an ethanolic extract of the red alga Rhodomela confervoides. By spectroscopic and chemical methods including HRMS and 2D NMR data, their structures were determined as 7-[3-bromo-2-(2,3-dibromo-4,5-dihydroxybenzyl)-4,5-dihydroxybenzyl]-3,7-dihydro-1H-purine-2,6-dione (1), 7-(2,3-dibromo-4,5-dihydroxybenzyl)-3,7-dihydro-1H-purine-2,6-dione (2, 9-[3-bromo-2-(2,3-dibromo-4,5-dihydroxybenzyl)-4,5-dihydroxybenzyl]adenine (3), (-)-8S-(3-bromo-5-hydroxy-4-methoxy)phenylalanine (4), (-)-3S-8-bromo-6-hydroxy-7-methoxy-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (5), methyl (-)-3S-8-bromo-6-hydroxy-7-methoxy-1,2,3,4-tetrahydroisoquinoline-3-carboxylate (6), and methyl (-)-3S-6-bromo-8-hydroxy-7-methoxy-1,2,3,4-tetrahydroisoquinoline-3-carboxylate (7). Compounds 5-7 were semisynthesized by using 4 as the starting material.
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Two different stocks (A and B) of the bay scallop Argopecten irradialls irradians (Lamarck, 1819) were used to test mass selection on growth. Stock A was a descending stock from the initial introduction from U.S.A. in 1982, which had been cultured in China for about 20 years. Stock B was the third generation from a recent introduction from U.S.A. in 1999. Truncation selection was conducted by selecting the largest 11% scallops in shell length from Stock A and the largest 12.7% scallops from Stock B as parents for the respective selected groups. Before the removal of parents for truncation selection, equal numbers of scallops were randomly chosen from Stock A and B to serve as parents for the control groups. Offspring from the four groups were reared under the same hatchery, nursery, and grow-out conditions. Values of response to selection and realized heritability at larvae, spat and grow-out stages for Stock B were all significantly (P < 0.001) higher than its counterpart for Stock A. For Stock A, no significant response to selection was observed (P > 0.05) at any stage, and the realized heritability for shell length was 0.015 +/- 0.024 for larvae, 0.040 +/- 0.027 for spat, and 0.080 +/- 0.009 for grow-out, respectively. For Stock B, however, significant (P < 0.05) response to selection was observed, and the realized heritability for shell length was 0.511 +/- 0.010 for larvae, 0.341 +/- 0.022 for spat, and 0.338 +/- 0.015 for grow-out. On average, responses to selection at the three stages for Stock B was 30 x, 7.1 x, and 3 x higher than its counterpart for Stock A, respectively. Accordingly, realized heritability at above stages for Stock B was 33 X, 7.5 x, and 3.2 X higher than its counterpart for Stock A, respectively. Differences in response to selection and realized heritability between the two stocks are presumably due to differences in genetic variability. As the 20th generation from the initial introduction consisted of only 26 scallops, Stock A is known to be highly inbred, while inbreeding in Stock B is negligible. (C) 2004 Elsevier B.V. All rights reserved.
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Three kinds of Schiff bases of carboxymethyl chitosan (CMCTS) were prepared, and their antifungal activities were assessed according to Jasso de Rodriguez's method. The results indicated that 2-(2-hydroxybenzylideneamino)-6-carboxymethylchitosan (HNCMCTS) and 2-(5-chloro-2-hydroxybenzylideneamino)-6-carboxymethylchitosan (HCCMCTS) had better inhibitory effects than those of chitosan or CMCTS against Fusarium oxysporium f. sp. vasinfectum, Alternaria solani, and Valsa mali. (c) 2005 Elsevier Ltd. All rights reserved.
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对海北定位站分布的金露梅灌丛草甸、矮嵩草草甸、藏嵩草沼泽化草甸3种高寒植被类型群落结构、感热(H)和潜热(LE)通量比较观测表明,3种植被类型年地上净初级生产力表现出矮嵩草草甸(318.600 g/m~2)>藏嵩草沼泽化草甸(258.341 g/m~2)>金露梅灌丛草甸(217.6 g/m~2).植物种类组成有矮嵩草草甸(54种)>金露梅灌丛草甸(47种)>沼泽草甸(24种).3种植被类型区近地表大气能量交换过程中,LE和H的月际变化明显,而且随植被类型的不同月际变化差异显著.3种不同植被类型在年内均表现出H+L E>0,表明在青海海北高寒草甸地区,太阳辐射强烈,近地层湍流输送明显,地表为-热源.3类型高寒草甸植被的年地上净生产量基本与波文比(β)呈现正效应,与LE+H呈现明显的反效应.植物种类组成基本与LE+H有反效应,与β呈明显的正效应.
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为了解青海省春小麦收割后田间堆放期间产量和品质的变化,选择近年育成的春小麦品种“高原205”(白粒,易穗发芽)、“高原115”(紫黑色小麦)、“高原448”(红粒)和“高原314”(白粒)以及曾为青海省主栽品种的“青春533”(红粒)为材料,收割后以农民常用的田间堆放方式进行堆放,每隔9d对其进行采样,测定产量、SDS沉淀值和降落数值的变化。结果表明,随着堆放时间的延长,收获产量逐步下降,平均产量从第1次采样(Od)时的504g/m^2减少到63d后的384g/m^2,收获产量平均值与取样时间直线回归F值为20.91,大于F0.01(6.90);SDS沉淀值变化较小,F值为0.90,小于F0.05(2.13);降落数值在取样时间点上差异极显著.F值等于46,72,大于F0.01(2.87)。高原205的降落数值一直呈现下降趋势,而高原448、高原115、高原314和青春533的变化是在O~18d间上升,然后下降。总体而言,田间堆放对收获产量和品质不利。
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分析高寒草甸不同土地利用格局下土壤CO2的释放量大小表明,在植物生长季的5~9 月,土壤CO2 释放量大小排序为:金露梅灌丛草甸(1871.40g/ m2) > 矮嵩草草甸(1769.63g/ m2) > 退化金露梅灌丛草甸(1495.60g/m2) > 退化矮嵩草草甸(1191.26g/ m2) ;而在植物非生长季的10月到翌年4月,其土壤CO2 释放量大小与植物生长季略有差异, 表现出矮嵩草草甸(661.46g/ m2 ) > 金露梅灌丛草甸( 550.90g/ m2 ) > 退化矮嵩草草甸(502.50g/ m2) > 退化金露梅灌丛草甸(384.50g/ m2) 的特点;全年内表现为矮嵩草草甸(2431.09g/ m2 ) > 金露梅灌丛草甸(2422.30g/ m2) > 退化金露梅灌丛草甸(1880.10g/ m2 ) > 退化矮嵩草草甸(1694.06g/ m2 ) . 高寒草甸地区不同土地利用格局土壤CO2 释放数量的差异及季节变化,不仅与各利用格局的土壤生物活性及土壤物理化学性状有关,而且与气象条件(特别是温度) 及其土壤冬季冻结期长短关系极为密切。
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To characterize evapotranspiration (ET) over grasslands on the Qinghai-Tibetan Plateau, we examined ET and its relevant environmental variables in a Kobresia meadow from 2002 to 2004 using the eddy covariance method. The annual precipitation changed greatly, with 554, 706, and 666 mm a(-1) for the three consecutive calendar years. The annual ET varied correspondingly to the annual precipitation with 341, 407, and 426 mm a(-1). The annual ET was, however, constant at about 60% of the annual precipitation. About 85% annual ET occurred during the growing season from May to September, and the averaged ET for this period was 1.90, 2.23, and 2.22 mm/d, respectively for the three consecutive years. The averaged ET was, however, very low (< 0.40 mm/d) during the nongrowing season from October to April. The annual canopy conductance (gc) and the Priestley-Taylor coefficient (a) showed the lowest values in the year with the lowest precipitation. This study first demonstrates that the alpine meadow ecosystem is characterized by a low ratio of annual ET to precipitation and that the interannual variation of ET is determined by annual precipitation.
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给出了一种超高压输电线路巡检机器人控制系统的设计与实现方法.根据机器人的作业任务,提出了基于传感器信息、约束信息以及动作反馈信息作为输入,产生式系统作为动作输出的越障控制方式.仿真结果表明此方法对于机器人的越障过程是有效的.
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关于全球CO2汇的位置、大小、变化和机制目前仍不确定, 还存有争议. 在理论计算和野外观测数据证明的基础上发现, 可能存在一种由全球水循环产生的重要的CO2汇(以溶解无机碳-DIC的形式). 这个汇达到0.8013 Pg C/a(约占人类活动排放CO2总量的10.1%, 或占所谓的遗漏CO2汇的28.6%), 它是由水对CO2的溶解吸收形成的, 并随着碳酸盐的溶解及水生植物光合作用对CO2的消耗的增加而显著增加. 这部分汇中有0.5188 Pg C/a通过海上降水(0.2748 Pg C/a)和陆地河流(0.244 Pg C/a)进入海洋, 有0.158 Pg C/a再次释放进入大气, 还有0.1245 Pg C/a储存在陆地水生生态系统中. 因此, 净沉降是0.6433 Pg C/a. 随着全球变暖引起的全球水循环的加强、CO2和大气圈中碳酸盐粉尘的增加, 还有造林地区的增多(会引起土壤CO2的增加进而导致水中DIC浓度的增大), 这部分汇也可能增加.
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本文研究了4价阳离子Zr、Hf在水合氧化铁(HFO)上的吸附及其在胶体/溶液界面的分异行为。研究结果表明:等价元素Zr、Hf在HFO上的吸附是非线性的,在吸附和共沉淀过程中二者发生了分异,Zr的吸附能力要大于Hf;pH<6时,固相中Zr/Hf比值随pH的升高迅速降低,而在天然水体pH范围内(pH≥6),Zr、Hf的吸附量Q及Zr/Hf比值则不随pH发生变化,显示了Zr、Hf在表生环境中的相对惰性行为。本研究为吸附/解吸或水/粒相互作用导致Zr、Hf在地表环境的分异提供了实验证据。