检索结果-南通市图书馆

Micromorphology of Surface Crusts in the Knersvlakte,South Africa

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Mountain science 2009年第2期6卷 189-196页

作者： Sarah-Jane C.Fox Anthony J.Mills Rosa M.Poch department of soil {2. Stellenbosch UniversityStellenbosch South Africa department of Environment and soil {2. University of LleidaRovira Roure 191 Lleida

soils in the Knersvlakte are particularly prone to crusting and have lower inherent infiltrability than other soils across western southern Africa. Micromorphological techniques were used to examine the structure and porosity of soil crusts in the Knersvlakte to ascertain why crusting is so intense in this region. Quantile regression using boundary lines was employed to examine the relationships between infiltrability and soil properties for all samples （n = 67）. This analysis showed that infiltrability is potentially maximal at low water- dispersible ＇clay plus silt＇ content and low silt content （r^2.= 0.72.and 0.64; respectively, n = 67）（Figure 2.. The strength of crusts, pH, EC, clay mineralogy, and water-dispersible clay, silt and ＇clay plus silt＇ content were compared, and a pore analysis using optical microscopy was undertaken on images of six soil thin sections （n = 6）（circular and parallel polarizers）. Pore analysis was further undertaken on five horizontal slices of equal dimensions taken through each soil thin section. The porosity samples with low infiltrability （〈 100 mm·hr^-1, n = 4） had greater crust strength, lower porosity （both total and in the least porous slice） and greater water-dispersible ＇day plus silt＇ and silt content than the porosity samples with high infiltrability （〉 100mm·hr^-1, n = 2.. The porosity samples with low infiltrability showed a trend of lower pH and greater water dispersible clay percentage. Porosity varied within the porosity samples due to the presence of dense clay/silt bands （〈 0.5 mm in width） with relatively few air vesicles. The porosity samples with horizontal slices of low porosity （but large numbers of air vesicles） had low infiltrability, while those without slices of low porosity （and relatively few air vesicles） had high infiltrability. We conclude that the intense crusting and resultant low infiltrability of soils in the Knersvlakte appears to be related to the formation of thin, dense clay/silt bands in the

关键词： Infiltrability optical microscopy porosity air vesicles

Tissue-specific expression of glutathione S-transferases induced by 2.tridecanone or quercetin in cotton bollworms, Helicoverpa armigera (Hübner)

在线全文

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2005年第11期15卷 988-992页

作者： TANG Fang, LIANG Pei and GAO Xiwu (department of Entomology, China agricultural {2., Beijing 100094, China) department of Entomology China Agricultural University Beijing 100094 China

The tissue-specific expression of glutathione S-transferases (GSTs) in the cotton bollworm and the expression level induced by 2.tridecanone and quercetin were examined using the methods of biochemistry and the quantitative PCR. The relative expression level of GST mRNA was unanimous with the GSTs activity conjugaging with 1-chloro-2. 4-dimitro-benzene (CDNB) in fat bodies, midguts, heads and integuments of cotton bollworms. The GSTs activity in fat bodies was the highest, then midguts, heads and integuments in turn, which was in consistent with the relative expression level of GST mRNA. The specific activity of GSTs and the relative expression level of GST mRNA could be significantly induced by 2.tridecanone and quercetin, and after the induction the order of the GSTs activity and the relative expression level of GST mRNA in the above four tissues in cotton bollworms was not different from the control. The induction of GSTs by 2.tridecanone was stronger than by quercetin in all four tissues, which was in accordance with the relative expression level of GST mRNA. It suggested that the increase of GSTs activity induced by plant allelochemicals was associated with the elevated expression of GST mRNA in cotton bollworms.

关键词： Helicoverpa armigera glutathione S-transferase tissue-specific expression plant allelochemicals.

Salt Contents in soils Under Plastic Greenhouse Gardening in China

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Pedosphere 2001年第4期11卷 359-367页

作者： LIWENQING S．VANDERZEE 等 CollegeofResourcesandEnvironment ShandongAgriculturalUniversityTainan271018（China） Sub－departmentofsoil{2.andPlantNutrition WageningenAgriculturalUniversityP.O.Box80056700EC

Field experiments were conducted on three main soils, brown soil, meadow soil and cinnamon soil, of Shandong Province to study the effect of plastic greenhouse gardening on soil salt contents. As compared to the open fields, the soil nutrient contents in the fields under plastic greenhouse gardening all increased significantly. The organic matter, quickly available N and P increases were extremely significant and the quickly available K increase was also significant. Along with the nutrient increases the soil salt contents increased clearly in all the soils investigated not only in the top layer but also in the deeper layers, being extremely significant in the 0～10 cm layer and significant in the 10～40 cm layers. The salt contents in the plastic greenhouses had significant correlations with the soil available nitrogen and phosphorous. soils with longer plastic greenhouse gardening time tended to have more salt. The plastic greenhouse soils contained less CO-3～(2.) and much more NO-3 than the open soils, which indicated a higher influence of human intervention in plastic greenhouses. Among the constituent ions, Cl～(-), NO-3～(-) , Ca～(2.) and Mg～(2.) had positive while HCO-3～(-) had negative significant or extremely significant correlations with total salt, with correlation coefficients being 0.66*, 0.80**, 0.92.*, 0.80** and -0.64* , respectively. Nitrate decreased from the top to deeper layers both in the plastic greenhouses and in the open fields. The plastic greenhouse soils contained much more nitrate than the open fields in every layer and even the nitrate contents of the 80～l00 cm layer were still several times those of the top layer in the open fields. The main reason for the salt increases was considered to be the inappropriate fertilization and selective absorption of nutrients by plants in the plastic greenhouses. The methods recommended to avoid soil salt increase in the plastic greenhouses were to apply fertilizers rationally according to the soils, veget

关键词： fertilization nitrate plastic greenhouse salt content vegetable

Environmental Factors Affecting Chromium-Manganese Oxidation-Reduction Reactions in soil

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2011年第1期21卷 84-89页

作者： D.O.P.TREBIEN L.BORTOLON M.J.TEDESCO C.A.BISSANI F.A.O.CAMARGO department of agricultural Engineering Federal University of Santa Catarina department of soil {2. Federal University of Rio Grande do Sul

Disposal of chromium （Cr） hexavalent form, Cr（Ⅵ）, in soils as additions in organic fertilizers, liming materials or plant nutrient sources can be dangerous since Cr（Ⅵ） can be highly toxic to plants, animals, and humans. In order to explore soil conditions that lead to Cr（Ⅵ） generation, this study were performed using a Paleudult （Dystic Nitosol） from a region that has a high concentration of tannery operations in the Rio Crande do Sul State, southern Brazil. Three laboratory incubation experiments were carried out to examine the influences of soil moisture content and concentration of cobalt and organic matter additions on soil Cr（Ⅵ） formation and release and manganese （Mn） oxide reduction with a salt of chromium chloride （CrCl3） and tannery sludge as inorganic and organic sources of Cr（Ⅲ）, respectively. The amount of Cr（Ⅲ） oxidation depended on the concentration of easily reducible Mn oxides and the oxidation was more intense at the soil water contents in which Mn（Ⅲ/Ⅳ） oxides were more stable. Soluble organic compounds in soil decreased Cr（Ⅵ） formation due to Cr（Ⅲ） complexation. This mechanism also resulted in the decrease in the oxidation of Cr（Ⅲ） due to the tannery sludge additions. Chromium（Ⅲ） oxidation to Cr（Ⅵ） at the solid/solution interface involved the following mechanisms： the formation of a precursor complex on manganese （Mn） oxide surfaces, followed by electron transfer from Cr（Ⅲ） to Mn（Ⅲ or Ⅳ）, the formation of a successor complex with Mn（Ⅱ） and Cr（Ⅵ）, and the breakdown of the successor complex and release of Mn（Ⅱ） and Cr（Ⅵ） into the soil solution.

关键词： cobalt Cr(VI) oxidation Mn oxides soil moisture tannery sludge

Mechanisms of Difference in Mn Efficiency Between Wheat and Oilseed Rape

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2000年第3期10卷 213-220页

作者： FANGZHENG ZHANGFUSUO MountainousDistrictInstituteofHebeiagriculturaluniversity Baoding071001China departmentofPlantNutrition ChinaAgriculturalUniversityBeijing100094China

By solution culture experiment, three wheat genotypes (Ttiticum aestivum L.) and two oilseed rape genotypes (Brassica napus L.) differing in Mn efficiency under Mn-deficient conditions were used to study mechanisms of the difference in Mn efficiency between wheat and oilseed rape. The results showed that there were significant differences in the abilities of MnIV reduction and acidification in root rhizosphere between the two species. Compared with wheat, oilseed rape had much higher reducing capacity and intensity of rhizosphere acidification under Mn-deficient conditions. Moreover, the higher ratio of functional leaves Mn/old leaves Mn in oilseed rape than in wheat was also an important factor for the different Mn efficiencies between the two species.

关键词： genotypic difference mechanism Mn efficiency oilseed rape whL

Influence of Chelating Agents on Chromium Fate in Sediment

在线全文

学校读者我要写书评

暂无评论

Pedosphere 1996年第2期6卷 163-166页

作者： WANG XIAOCHANG SUN JINHE ZHANG QINZHENG CAO ZHIHONG and CHEN ZIYUAN(Institute of soil science,Academia Sinica,Nanjing 2.0008 China)(Zhejiany {2. university,Hangzhou 31002. China) Institute of soil science Academia Sinica Nanjing 210008 China Zhejiang agricultural university Hangzhou 310029 China

A laboratory investigation on reaction between chelating agents and chromium was conducted to evaluate the effect of chelating agents on the adsorption and desorption of chromium in sediment. The amount of adsorbed chromium(VI) in sediment decreased slightly by 5%-10% because of addition of chelating *** agents inhibited the remodel of Cr(Ⅲ) by sediment from solutions and the inhibiting effect was in the order:citric acid > tartaric acid > EDTA, salicylic *** effect of chelating agents on desorption of chromium in sediment was observed.

关键词： adsorption chelating agent Cr desorption sediment

Studies on the quality improvement of frozen semen of bull with treatment of helium-neon laser

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Lasers 1993年第6期 87-90页

作者： Wenbin Yue, Kelu Li(Animal science department, {2. agricultural university, taigu, {2. 030801 China)Jianxin Lu ({2. Animal Husbandry Bureau,China)Chaohui Huo(Biological Drugs Manufacturing Plant of Veterinary Medicine, {2. Province,China)

Studies on the improvement of the quality of bull’s forzen semen witht reatment of He-Ne laser are presented. It is found experimently that the quality of forzen semen is greatly improved with proper irradiation dose of laser. For two treated groups with 2.7J/cm~2.and 4.5J/cm~2.doses, the unfrozen vitality, respiration, fructose utilization and ~32.i intake are much higher (p2.7J/cm~2.dose. The mechanism on the improvement of semon quality with laser irradiation is investigated.

关键词： Bull frozen semen Helium-neon laser

Polymorphisms of three gene-derived STS on pig chromosome 13q41 are associated with susceptibility to enterotoxigenic Escherichia coli F4ab/ac in pigs

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science China(Life sciences) 2008年第7期51卷 614-619页

作者： HUANG Xiang 1 ,REN Jun 1 ,YAN XueMing 1,2.,PENG QiuLing 1 ,TANG Huan 1 ,ZHANG Bo 1 ,JI HuaYuan 1 , YANG ShuJin1&HUANG LuSheng 1 1Key Laboratory for Animal Biotechnology of Jiangxi Province and the Ministry of Agriculture of China,Jiangxi agricultural university, Nanchang 330045,China 2.2. of Biology,Nanchang university of science and Technology,Nanchang 330038,China 1. Key Laboratory for Animal Biotechnology of Jiangxi Province and the Ministry of Agriculture of China Jiangxi Agricultural University Nanchang 330045 China 2. department of Biology Nanchang University of Science and Technology Nanchang 330038 China

Neonatal diarrhea caused by enterotoxigenic Escherichia coli(ETEC)F4 is a common and serious disease,resulting in significant economical loss in the pig *** locus encoding ETEC F4 receptor has been mapped to pig chromosome(SSC)13q41,and one of the most significantly linked markers is *** this study,we selected three genes including SLC12.8,MYLK and KPNA1 from a chromosomal region flanking S0075 on SSC13 to develop pig specific sequence tagged sites(STS). Seven single nucleotide polymorphisms were identified in the three pig STS using DNA of four full-sib susceptible and resistant animals in a White Duroc×Erhualian *** grandparents,parents and 755 offspring in the intercross were genotyped for three polymorphisms,including SLC12.8 g.159A>G,MYLK g.1673A>G and KPNA1 g.306A>***-based transmission disequilibrium test(TDT) revealed that all polymorphisms and the corresponding haplotypes are significantly associated with ETEC F4ab/ac(especially F4ac)brush border adhesion phenotypes,indicating that these polymor- phism are in linkage disequlibrium with causal mutation(s)of the gene encoding ETEC F4ab/ac receptor. Our results strengthen the evidence for the involvement of SSC13q41 in high acquiring risk of ETEC F4ab/ac infection,and provide novel polymorphic markers for fine mapping of the ETEC F4ab/ac receptor locus.

关键词： pig SSC13q41 sequence tagged sites(STS) Escherichia coli(ETEC)F4ab/ac susceptibility

Cobalt in alluvial Egyptian soils as affected by industrial activities

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental sciences 2002年第1期14卷 34-38页

作者： Ensegam A.M. Zohny (Physics department, Faculty of science, Cairo {2., Beni Swif Branch, Egypt) Physics department Faculty of Science Cairo University Beni-Swif branch Egypt

Twenty five surface (0—2. cm) soil samples were collected from different locations in Egypt representing non polluted, moderately and highly polluted soils. The aim of this study was to evaluate total Co content in alluvial soils of Delta in Egypt using the delayed neturen activation analysis technique (DNAA). The two prominent gamma ray lines at 1173 2.and 1332. 5 keV was efficiently used for 60 Co determination. Co content in non polluted soil samples ranged between 13 12.to 2. 2. ppm Co with an average of 18 16±4.38 ppm. Cobalt content in moderately polluted soils ranged between 2. 5 to 30 00 ppm with an average of 2. 3±1.3 ppm. The highest Co levels (ranged from 36 to 64 69 ppm with an average of 51 9±9.5); were observed in soil samples collected from, either highly polluted agricultural soils due to prolonged irrigation with industrial wastewater or surface soil samples from industrial sites.

关键词： cobalt neturen activation analysis technique (DNAA) surface soil sample industrial activities