999 resultados para 32-310


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IEECAS SKLLQG

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研究通过测量中子和γ剂量当量率估算 5 2MeV/u32 S束轰击Ta靶时的中子与γ光子产额的方法 ,并给出了估算结果。

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利用32P同位素示踪法对白浆土中P肥利用率进行了研究.结果表明,在岗地白浆土上,表层土壤表现出一定程度的供P不足现象,白浆层土壤有效P含量严重缺乏.表层土壤中当季P肥利用率的变幅范围为6.09~12.35%,白浆层土壤P肥利用率为13%左右.施用有机肥能明显提高白浆土OlsenP的含量,加速土壤本身P的活化,各种有机物中,以猪粪对土壤潜在P的活化效果最好.将OlsenP与X值、A值比较,认为OlsenP是评价白浆上P肥力简便易行的可靠指标.

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采用光解试验,研究了紫外照射与纳米TiO2联合作用下,土壤表层中苯并[a]芘(BaP)的降解动力学;同时考察了催化剂的浓度、土壤pH、腐植酸和光质对BaP的光催化降解的影响。结果表明,土壤中BaP的光催化降解表现为准一级动力学。催化剂TiO2可以明显地促进土壤中BaP的光降解,较少量的催化剂(0.5%)使光解的半衰期从363.22h减少到103.26h。H+和OH-离子对BaP的催化光解起促进作用,在酸性和碱性土壤中BaP光催化降解高于中性土壤,酸性土壤中的降解速率最快。腐殖质吸收紫外光照射时,产生的活性氧中间产物能够攻击BaP,添加腐植酸能增加土壤表层中BaP的光催化降解。BaP的光解半衰期从无外加腐植酸的89.34h,减少到添加浓度分别为5、10、20和40mg·kg-1的29.37、32.69、35.73和38.51h。BaP的催化降解随波长的增加而降低,在波长254、310和365nm下,BaP降解的一级动力学常数分别为0.0078h-1、0.0061h-1和0.005h-1。

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对以实验数据为基础建立的初步空间模型进行了验证 ,并用 Maunder和 Mauring的线性回归模型对苇田子模型进行了修正。模拟结果显示 ,辽河三角洲 8万 hm2 苇田每年灌期大约可以去除 32 0 0~ 4 0 0 0 t总氮和 80 t的活性磷 ,但这仅相当于其潜力的 1 /1 0。因此 ,运用河口湿地作为富含营养物质河水入海前的最后过滤屏障 ,对于防止近海水体的富营养化具有重要意义。

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Calixarene-capped Co-32 clusters are constructed by a sodalite Co-24(II) cage and an encapsulated Co-8(III) cube. The spherical units are arranged into three isomeric structures, two of which are stacked by the bcc lattices and the third of which is assembled by the cubic closest packing of the spherical units.

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The effect of doping with various amount of Sb (0.06-0.32) to (Bi,Pb):Sr:Ca:Cu = 1:1:1:1 system were studied with XRD and Tc measurements. The presence of Sb promotes the conversion of low Tc phase (2212 phase) to high Tc phase (2223 phase) and at around Sb = 0.18 the 2212 phase nearly completely disappears; but at the same time a new phase of unknown structure appears even with Sb = 0.06 showing that the incorporation of Sb into the Bi-based superconducting phase is of very low concentration. Tc measurements show that the optimum concentration of Sb-doping is around 0.10 and that unknown phase has an adverse effect to the superconducting properties; a composition disproportion at the surface of pellet was observed.

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根据天然草地退化程度的差异,采用松耙+补播+施肥+封育(退化较严重的草地)、封育+施肥(轻度退化草地)等措施,植物群落物种组成、多样性等特征值及其植被盖度发生明显变化.研究第2年结果表明,物种数封育+施肥处理最高(32种),对照居中(26种),补播+施肥处理最低(13种);多样性指数大小依次为封育+施肥(3.126)、对照(2.819)、补播+施肥(1.494);均匀度指数大小依次为封育+施肥(0.902)、对照(0.865)、补播+施肥(0.582);群落总盖度大小依次为封育+施肥(85.9%)、补播+施肥(79.7%)、对照(72.9%);补播+施肥+封育处理后地上生物量最大(460.65 g/m2),原生植被+封育+施肥处理居中(310.14 g/m2),对照最低(178.96 g/m2);地下生物量大小依次为封育+施肥(6 920.37 g/m2)、补播+施肥(1 458.96 g/m2)、对照(828.91 g/m2);补播+施肥+封育处理优良牧草较对照提高近50倍,杂草类减少82.81%,封育+施肥处理较对照良牧草比例提高48倍,杂草类比例减少80.46%.半人工草地通过灭除杂草和施肥相结合的示范试验表明:单纯进行灭杂,地上生物量减少,灭杂和施肥相结合不仅可提高地上生物量,而且可提高优良牧草的比例;不同处理区土壤养分含量各不相同,其中封育+施肥处理全氮、全碳、有机碳最高,对照居中,补播+施肥较低.

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2004

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BACKGROUND:The Framingham Heart Study (FHS), founded in 1948 to examine the epidemiology of cardiovascular disease, is among the most comprehensively characterized multi-generational studies in the world. Many collected phenotypes have substantial genetic contributors; yet most genetic determinants remain to be identified. Using single nucleotide polymorphisms (SNPs) from a 100K genome-wide scan, we examine the associations of common polymorphisms with phenotypic variation in this community-based cohort and provide a full-disclosure, web-based resource of results for future replication studies.METHODS:Adult participants (n = 1345) of the largest 310 pedigrees in the FHS, many biologically related, were genotyped with the 100K Affymetrix GeneChip. These genotypes were used to assess their contribution to 987 phenotypes collected in FHS over 56 years of follow up, including: cardiovascular risk factors and biomarkers; subclinical and clinical cardiovascular disease; cancer and longevity traits; and traits in pulmonary, sleep, neurology, renal, and bone domains. We conducted genome-wide variance components linkage and population-based and family-based association tests.RESULTS:The participants were white of European descent and from the FHS Original and Offspring Cohorts (examination 1 Offspring mean age 32 +/- 9 years, 54% women). This overview summarizes the methods, selected findings and limitations of the results presented in the accompanying series of 17 manuscripts. The presented association results are based on 70,897 autosomal SNPs meeting the following criteria: minor allele frequency [greater than or equal to] 10%, genotype call rate [greater than or equal to] 80%, Hardy-Weinberg equilibrium p-value [greater than or equal to] 0.001, and satisfying Mendelian consistency. Linkage analyses are based on 11,200 SNPs and short-tandem repeats. Results of phenotype-genotype linkages and associations for all autosomal SNPs are posted on the NCBI dbGaP website at http://www.ncbi.nlm.nih.gov/projects/gap/cgi-bin/study.cgi?id=phs000007.CONCLUSION:We have created a full-disclosure resource of results, posted on the dbGaP website, from a genome-wide association study in the FHS. Because we used three analytical approaches to examine the association and linkage of 987 phenotypes with thousands of SNPs, our results must be considered hypothesis-generating and need to be replicated. Results from the FHS 100K project with NCBI web posting provides a resource for investigators to identify high priority findings for replication.