992 resultados para orientamento :: 365 :: Geoingegneria
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The Nernstian plots in a spectropotentiostatic experiment for complex electrode processes were studied theoretically. The plots are linear for an electron transfer process coupled with a preceding or succeeding chemical reaction, and the electron stoichio
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In this pare earth-HEDTA-serine (Ser) ternary system has been studied by potentiometric titration at 25 degrees C with an ionic strength of 0.15 mol.L-1 (NaCl). The excitation and fluorescence spectra of TbCl3, Tb-Ser, Tb-HEDTA and Tb-HEDTA-Ser have hem determined at room temperature. The stability constants of these ternary complexes have been obtained, It lieu been found that Tb-HEDTA-Ser ternary system exhibit characteriatic fluorescence spectrum of Tb3+ sensitized by two ligands,The results mean that the chemical hood between the control ion and the ligand in this ternary system is predominantly ionic in character,and the energy transfer from ligand to Tb8+ is performed by a kind of abort-range electron exchange action.
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氨基多羧酸是镧、锕系元素促排剂,氨基酸是重要的生物配体。稀土-氨基多羧酸-氨基酸三元体系的研究对探索稀土在人体内代谢及其生物效应具有重要意义,其次,多元配位体系荧光研究亦是令人感兴趣的课题。有关稀土-氨基多羧酸-氨基酸三元体系研究不多,稀土-N-羟乙基乙二胺三乙酸(HEDTA)-丝氨酸(Ser)三元体系研究尚未见报导。本文用pH电位法和荧光光谱研究了稀土(除钷外镧系元素及钇)-HEDTA-Ser三元体系的配位作用,考察了铽配合物配体敏化荧光光谱特点。
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以UV-365型分光光度计测量单掺或多掺过渡金属Fe、Ti、Cr、Ni、V、Co等20个人工刚玉样品的透射光谱。给出着色离子在刚玉中调色和补色的试验结果。着色离子在刚玉中透射光谱可通过分散离子的电子跃迁或不同价态间电荷传输来解释。掺有Fe或Ni合成刚玉经γ辐照后变为黄色,其辐照效应通过黄色的蓝宝石色心理论加以解释。
Formation and early development of tetraspores of Polysiphonia urceolata (Rhodomelaceae, Rhodophyta)
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Polysiphonia urceolata is one type of potential commercial red seaweeds used for breeding and cultivation, because of its significant biochemical and biomedical application. However, the information of breeding and seedling incubation for cultivation is limited, especially the early development. In this study, tetrasporohyte and gametophyte of P. urceolata were taken as the study materials in Huiquan Bay, Qingdao, China. The cleaned and sterilized tetrasporophytes and gametophytes were pre-cultured in sterilized seawater, then nurtured at 18A degrees C, 25 mu mol photons m(-2) s(-1) in 12:12 h (light:dark) photoperiod. Continuous observation under microscope showed that the early development consists of bipolar division stage and seedling stage. In the division stage, tetraspores germinate into bipolar sporelings that further differentiate into a colorless rhizoidal portion and a lightly pigmented upright shoot. The lightly pigmented rhizoidal cell develops to a rhizoid and the larger pigmented cell transforms to an erect axis. In the seedling stage, several quasi-protuberances appear on the erect axis and form juvenile seedlings. The results demonstrate the culture of P. urceolata from tetraspores under laboratory conditions.
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In this study, we chronicle the establishment of a novel transformation system for the unicellular marine green alga, Dunaliella salina. We introduced the CaMV35S promoter-GUS construct into D. saliva with a PDS1000/He micro-particle bombardment system. Forty eight h after transformation, via histochemical staining, we observed the transient expression of GUS in D. salina cells which had been bombarded under rupture-disc pressures of 450 psi and 900 psi. We observed no GUS activity in either the negative or the blank controls. Our findings indicated that the micro-particle bombardment method constituted a feasible approach to the genetic transformation of D. salina. We also conducted tests of the cells' sensitivity to seven antibiotics and one herbicide, and our results suggested that 20 mu g/ ml of Basta could inhibit cell growth completely. The bar gene, which encodes for phosphinothricin acetyltransferase and confers herbicide tolerance, was introduced into the cells via the above established method. The results of PCR and PCR-Southern blot analyses indicated that the gene was successfully integrated into the genome of the transformants.
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Large-insert bacterial artificial chromosome (BAC) libraries are necessary for advanced genetics and genomics research. To facilitate gene cloning and characterization, genome analysis, and physical mapping of scallop, two BAC libraries were constructed from nuclear DNA of Zhikong scallop, Chlamys farreri Jones et Preston. The libraries were constructed in the BamHI and MboI sites of the vector pECBAC1, respectively. The BamHI library consists of 73,728 clones, and approximately 99% of the clones contain scallop nuclear DNA inserts with an average size of 110 kb, covering 8.0x haploid genome equivalents. Similarly, the MboI library consists of 7680 clones, with an average insert of 145 kb and no insert-empty clones, thus providing a genome coverage of 1.1x. The combined libraries collectively contain a total of 81,408 BAC clones arrayed in 212 384-well microtiter plates, representing 9.1x haploid genome equivalents and having a probability of greater than 99% of discovering at least one positive clone with a single-copy sequence. High-density clone filters prepared from a subset of the two libraries were screened with nine pairs of Overgos designed from the cDNA or DNA sequences of six genes involved in the innate immune system of mollusks. Positive clones were identified for every gene, with an average of 5.3 BAC clones per gene probe. These results suggest that the two scallop BAC libraries provide useful tools for gene cloning, genome physical mapping, and large-scale sequencing in the species.
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滤食性贝类以水体中的浮游植物和有机碎屑为主要食物,养殖海域的初级生产力水平、水动力学特性等生态环境因子的差异,不仅直接影响养殖贝类的产量,而且也与贝类养殖活动对生态环境的压力密切相关。由于养殖的种类、密度、方式及养殖海域的特性不同,关于贝类对生态环境的影响往往有不同的结果。本文以我国北方大连獐子岛扇贝底播海区和荣成桑沟湾贝类筏式养殖区为研究对象,采用现场调查、室内受控实验及生态数值模型模拟方法,分析研究了滤食性贝类对海域生态系统的影响,对这两个海域贝类养殖的生态容量进行了初步的评价。 主要结果: 1. 獐子岛海域底播贝类养殖活动对该海域生态系统的影响较小。非参数统计—符号检验的结果显示,养殖区与非养殖区之间的溶解性无机氮、磷酸盐浓度、氮磷摩尔比及浮游植物群落结构没有统计学上的差异(p>0.05)。但是从变化的趋势上来看,贝类养殖活动对水域环境的某些参数有一定程度的影响。例如,獐子岛底播贝类养殖海域的溶解性无机氮以氨氮为主,可能与贝类的代泄活动有关;不论是叶绿素浓度,还是网采浮游植物的生物量都是贝类高密度养殖区<贝类低密度养殖区<非养殖区(7月份除外),这种趋势可能与贝类的摄食压力有关。 桑沟湾各环境指标表现出明显的区域性。除春季外,非养殖区的DIN浓度高于各养殖区。在春季和冬季,贝类区的磷酸盐浓度显著降低;而硅酸盐浓度在夏季和秋季显著增大。综合分析DIN、PO4-P及SiO3-Si三个参数的四季变化,海带区、贝藻区及贝类区发生显著性变异的概率分别为25%,42%和50%,贝类区的变异较大。浮游植物、小型浮游动物的生物多样性指数都是以非养殖区为最高,贝类区的多样性指数最低。尤其是浮游动物的丰度,贝类区显著低于非养殖区。 2. 利用挪威的MOM (Modelling-Ongrowing fish farms-Monitoring)评价系统,评价了桑沟湾长期大规模的贝藻筏式养殖活动对底质环境的压力。在桑沟湾设10个取样站位,共获得66个底泥样品。比较了MOM-B评价系统的3组参数的季节变化特性。结果显示,底质条件属于1级,说明桑沟湾贝藻长期大规模的养殖活动对底质环境的压力较低。结合桑沟湾的环境及养殖特点,分析了压力较低的原因。 3. 经计算,2006年中国海水养殖的贝类和藻类使用浅海生态系统的碳可达396万吨,并通过收获从海中移出至少136.9万吨的碳。从1995年至2006年,养殖大型藻类和贝类累计移出的碳分别约为365万吨和893万吨,总计达1258万吨。证明了浅海的贝类和藻类养殖活动直接或间接地使用了大量的海洋碳,提高了浅海生态系统吸收大气CO2的能力。 4. 采用模拟现场生物沉积法测定了虾夷扇贝的滤水率、摄食率等生理指标及其与贝类个体大小、水温的关系。虾夷扇贝单位个体的滤水率与组织干重的关系符合幂函数方程CR=a×DWb,b值在0.45~0.65范围内;水温对虾夷扇贝滤水率的影响极其显著(p<0.01),温度(T)与滤水率(CR)呈抛物线的关系:CR=-0.0009T2+0.0188T-0.0306,水温为10℃时,虾夷扇贝的滤水率、摄食较大。 5. 采用模拟现场流水法测定了3种滤食性贝类的食物选择性。紫贻贝、长牡蛎及栉孔扇贝分别对直径4m, 6m 和 8m颗粒的保留效率达到最大值;对小颗粒(直径2m)的保留效率分别为17%, 19% 和 8%。栉孔扇贝对食物数量和质量浓度的变化相对敏感,随着数量浓度的增加,栉孔扇贝倾向于摄食较大的颗粒;随着颗粒食物质量浓度的增加,倾向于摄食较小的颗粒。 6. 獐子岛海域四个航次的调查结果显示,叶绿素浓度在1.23~2.85mg.m-3范围内,均值为1.78±0.57 mg.m-3;初级生产力的变化范围为30.4~117.0 mg C. m-2.d-1,平均值为76.6±41.9 mg C. m-2.d-1。通过虾夷扇贝生物量断面调查,获得了虾夷扇贝的壳高频率分布情况,7月份的众数值出现在100 mm,10月份壳高的众数值为80 mm。利用以上测定的虾夷扇贝的滤水率等基本生物学特性,结合虾夷扇贝的年产量、海域面积和有关的水文状况等数据,计算了滤水效率、摄食压力、调节比率3个食物限制性指标参数,全年的均值分别为0.048, 0.31和 0.16,都小于1,说明目前该海域虾夷扇贝的养殖量未达到养殖容量。 7. 利用STELLA软件,建立的桑沟湾贝藻养殖的数值模型,模拟了叶绿素a浓度及氮磷营养盐的周年变化情况,及其对贝类养殖生物量变化的响应。以叶绿素a浓度为指标,初步探讨了桑沟湾贝类的生态容量。
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Preliminary genetic linkage maps were constructed for the Pacific abalone (Haliotis discus hannai Ino) using amplified fragment length polymorphism (AFLP), randomly amplified polymorphic DNA (RAPD), and microsatellite markers segregating in a F, family. Nine microsatellite loci, 41 RAPD, and 2688 AFLP markers were genotyped in the parents and 86 progeny of the mapping family. Among the 2738 markers, 384 (including 365 AFLP markers, 10 RAPD markers, and 9 microsatellite loci) were polymorphic and segregated in one or both parents: 241 in the female and 146 in the male. The majority of these markers, 232 in the female and 134 in the male, segregated according to the expected 1:1 Mendelian ratio (alpha = 0.05). Two genetic linkage maps were constructed using markers segregating in the female or the male parent. The female framework map consisted of 119 markers in 22 linkage groups, covering 1773.6 cM with an average intermarker space of 18.3 cM. The male framework map contained 94 markers in 19 linkage groups, spanning 1365.9 cM with an average intermarker space of 18.2 cM. The sex determination locus was mapped to the male map but not to the female map, suggesting a XY-male determination mechanism. Distorted markers showing excess of homozygotes were mapped in clusters, probably because of their linkage to a gene that is incompatible between two parental populations.
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针对我国目前草原生态建设中存在的一些理论和实践问题,如草原退化的面积和程度,造成退化原因的作用和权重等不确定性问题;载畜量及其估测的理论基础问题;“围封转移”和“春季休牧”措施的理论基础以及草原生态系统多功能等问题.认为这些问题将严重困扰着我国草业能否健康、和谐的可持续发展,因此在研究我国草业发展战略时,必须面对并迫切需要解决.
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大量研究结果证实,人体摄入的碘80 %以上来自于食品,因此,碘缺乏病病区的形成应归因于植物含碘量的区域性差异。植物中的碘来自于大气和土壤,至今科学尚不能搞清在不同情况下,哪一部分碘占据主要部分。土壤中的碘与成土母岩中的碘含量基本无关,土壤碘含量主要决定于母岩风化产物对大气干湿沉降碘的吸收和保持能力。限于植物和大气中碘测定的困难,在碘的地球化学与碘缺乏病病区成因的问题上,目前仍有许多未解之谜。笔者提出,土壤中某种形态的碘可能以气态挥发并在近地大气层富集,存在植物吸收利用这一部分碘的条件的地区,不会有碘缺乏病的流行。
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北部湾发育一系列上新世玄武岩,其全岩K—Ar年龄为5.9—2.4Ma,是伴随北部湾盆地拉张而形成的一次较大规模的岩浆活动。岩石化学和微量元素地球化学研究表明,该玄武岩属于碱性玄武岩系,具有OIB型微量元素配分模式,形成于较均一的地幔源区,具有以EM2型地幔端元为主、混有HIMU和EMl型端元的地幔源区性质,形成于地幔柱或地幔热点的构造环境。北部湾盆地与红河剪切断裂带具有相同的地幔源区,而与受太平洋板块影响的地幔源区差别较大。玄武岩形成和北部湾盆地拉张主要受印度板块向欧亚板块俯冲导致的红河断裂带大规模剪切走滑控制,5Ma左右红河断裂带由左行走滑剪切转变为右行走滑剪切的构造性质转换可能是导致地幔异常扰动和岩浆活动的地球动力学机制。
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通过对老厂银铅锌多金属矿床地质地球化学特征的系统总结,并与相关海相火山岩块状硫化物矿床的对比,认为矿床期后岩浆热液叠加特征明姓,矿体直接容矿围岩为火山-沉积岩,矿床属火山.沉积岩容矿的块状硫化物矿床。为介于典型的火山岩容矿的块状硫化物矿床(VHMS)和典型沉积岩容矿的海底喷气沉积矿床(SEDEX)之间的过渡类型,其矿化特征与新疆可可塔勒铅锌矿床(伊比利亚型)相类似.
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REE geochemistry data from the Fanshan alunite deposit indicated that its ore-forming materials came chiefly from the country rocks, with δCe〉0 for alunite ores. According to the differences in δEu, the alunite ores were divided into three types: weak negative Eu anomaly, weak positive Eu anomaly and remarkable positive Eu anomaly. The phenomena of Ce-enrichment in the ores indicated that the Fanshan alunite deposit was formed in an oxidizing environment. Variations in fO2 are corresponding to those in δEu: Eu anomaly varies from negative to positive with increasing fO2. And two other important factors may impact the occurrence of Eu anomalies: the contents of alkaline feldspar and the protolith structure in the mineralization period.