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排序方式: 共有1437条查询结果,搜索用时 93 毫秒
931.
932.
Zhang Yunxia Li Tielong Jin Zhaohui Wang Wei Wang Shuaima 《Frontiers of Environmental Science & Engineering in China》2007,1(4):466-470
Denitrification of nitrate in groundwater using iron nanoparticles has received increasing interest in recent years. In order
to fabricate iron nanoparticles with homogeneously spherical shape and narrow size distribution, a simple and “green” method
was developed to synthesize iron nanoparticles. The conventional microemulsion methods were modified by applying Span 80 and
Tween 60 as mixed surfactants. The maximum content of water in the Water-in-oil (W/O) microemulsion and its appropriate forming
conditions were found, and then the microemulsion system consisting of saturated Fe2+ solution was used to synthesize α-Fe ultrafine particles by redox reaction. The nanoparticles were characterized by using
powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the average diameter of the
particle is about 80–90 nm. The chemical activity of the obtained iron nanoparticles was studied by the denitrification experiment
of nitrate. The results show that under the experimental conditions, iron removed most of the 80 mg/L nitrate within 30 min.
The mass balance of nitrate reduction with nanoscale Fe indicates that endproducts are mainly ammonia. Two possible reaction
pathways for nitrate reduction by nanoscale iron particles have been proposed in this work.
__________
Translated from Chemical Journal of Chinese Universities, 2006, 27(4): 672–675 [译自: 高等学校化学学报] 相似文献
933.
研究了硒化合物对长春花(C.roseus)细胞悬浮生长的影响.在pH5.5培养介质中,当Se(Ⅵ)>0.5ppm或Se(Ⅳ)>0.6ppm时,将抑制C.roseus细胞悬浮生长,其致死浓度分别是100ppm Se(Ⅵ)和2.0ppm Se(Ⅳ).C.roseus对硒化合物有效强的富集作用.硒化合物的毒性和培养介质的pH值有关.在本试验条件下,硒酸钠和亚硒酸钠对Hg2+无拮抗作用. 相似文献
934.
A routine study of the fetal karyotype was performed on samples obtained at 64 fetoscopic procedures. In 13 cases only pure amniotic fluid was available for the cultures, while in the remaining 51 cases the chromosome analysis was carried out on PHA-stimulated lymphocyte microcultures set up with any excess fetal blood above the requirements for globin-chain synthesis. Karyotype could be determined on fetal lymphocytes in 44 cases (86 per cent). All the fetuses were chromosomally normal. This experience shows that cytogenetic analysis using microaliquots of fetal blood is a relatively simple technique which should be introduced into routine prenatal diagnosis by fetoscopy. 相似文献
935.
介绍了炼化废水的特点及以A/O法为核心的污水处理设施的运行状况,探讨生产中存在的问题,并进行相应的改造,通过优化运行,使出水达标排放。 相似文献
936.
Menkes X-linked disease, a copper disturbance syndrome, is detectable in cell cultures. Prenatal findings in two at-risk foetuses suggested that prenatal diagnosis was also feasible. In this study, we report substantial evidence that therapeutic abortion can be limited to hemizygous males. Forty-two at-risk pregnancies from 21 European families and 1 Canadian family were monitored with 64Cu-uptake into cultured amniotic fluid cells. In 10 pregnancies with a male karyotype an affected foetus was predicted on the basis of the copper studies. The pregnancies were terminated and the diagnosis was in each case confirmed by a markedly increased placenta copper content. Fourteen male foetuses were predicted to be unaffected and none of them has developed signs of Menkes disease after birth. In 6 of these cases the diagnosis was checked in the newborn boy by placenta copper measurements, and they all had copper concentrations within normal limits. Eighteen pregnancies with a female karyotype were also studied. 9 females could be identified as carriers on the basis of the tissue culture studies or raised placenta copper values. 相似文献
937.
A simple high resolution technique for human chromosomes is described for fibroblasts obtained from amniotic fluid cell cultures. The application and clinical significance of this technique in prenatal diagnosis is discussed. 相似文献
938.
用土柱环流装置作连续富集培养,分离到一株总状共头霉(Syncephalastrum racemosum),表现有转化杀苗剂甲霜灵的能力。当培养液中甲霜灵浓度在10μg/ml以下时,培养21天后甲霜灵含量减少80%以上。实验证明,这一菌株不能利用甲霜灵作为其生长碳源,在培养过程中甲霜灵的苯环结构并未分解。属于共代谢作用。 相似文献
939.
940.
在分析图书馆文化和图书馆能力的基础上,说明了图书馆文化和图书馆能力的辩证关系,进而探讨了图书馆文化在图书馆能力建设中是原动力,是一种心理和思想协调,强调的是人的发展,因而,体现了图书馆文化在图书馆能力建设中的价值. 相似文献