用二乙氨二硫代甲酸银分光光度法测定畜禽饮用水中的砷     

帕提曼·卡吾力  刘敏跃 《饲料工业》2011,32(9)

畜禽饮用水中砷在锌和酸作用产生新生态氢。在碘化钾和氯化亚锡存在下,使五价砷还原为三价砷。三价砷与新生态氢生成砷化氢气体。通过乙酸铅棉花去除硫化氢的干扰,然后与溶于三乙醇胺-三氯甲烷中的二乙氨基二硫代甲酸银作用,生成棕红色的胶态银,比色定量。结果试样含砷量m与吸光度B呈良好的线形关系,其回归方程为m=3.884 6×B-0.215 2,相关系数r=0.999 3,检出限为0.01 mg/l,对畜禽饮用水中的砷进行测定,相对标准偏差1.3。结论:方法灵敏,结果准确,适用于畜禽饮用水中砷的快速测定。  相似文献   

Prevalence and shedding patterns of Campylobacter spp. in longitudinal studies of kennelled dogs     

Parsons BN  Williams NJ  Pinchbeck GL  Christley RM  Hart CA  Gaskell RM  Dawson S 《Veterinary journal (London, England : 1997)》2011,190(2):249-254

Dog ownership is considered a risk factor for campylobacteriosis in humans. This study investigated the prevalence and shedding of Campylobacter spp. in kennelled dogs. Faecal samples (n=399) were collected in longitudinal studies from 52 dogs in two kennels. Campylobacter spp. were isolated using charcoal-based selective agars and direct PCR. The prevalence of Campylobacter spp. in dogs in boarding kennels ranged from 46% (95% CI 22, 72) on entry, to 50% (95% CI 30, 70) overall, and in dogs in 'rescue' kennels from 68% (95% CI 49, 84) on entry to 73% (95%, CI 56, 87) overall. C. upsaliensis was isolated from 62% (95% CI 48, 73) of the dogs, whilst C. jejuni was isolated from 15% (95% CI 7, 26) of animals. The majority of infected dogs entered the kennels already carrying Campylobacter spp., and remained infected throughout their stay. However, in some cases, shedding appeared to commence after kennelling. Given that the prevalence of C. upsaliensis and C. jejuni was relatively high in dogs from both boarding and rescue kennels, such animals may pose a zoonotic risk.  相似文献   

不同密度和果穗数对日光温室番茄冠层光合及产量的影响   总被引：3，自引：1，他引：2  

王强  王浩  闫鹏  阿不力肯木·沙土尔  热汗古丽·买合木提  艾尼瓦尔·克然木 《北方园艺》2011,(15):84-87

以“保红一号”番茄为试材,采用单干整枝方式研究不同密度和果穗数对日光温室番茄功能叶片冠层光合速率、叶绿素含量及产量的影响.结果表明:番茄净光合速率、叶绿素含量在植株上、中、下部冠层间随不同密度的冠高和叶位差异明显.中、上部净光合速率、叶绿素含量高,下部低,3 000株/667m2(留5穗果)各冠层叶位间叶绿素含量与净光合速率呈正相关,表现出冠层净光合速率、叶绿素含量和产量最高.表明适合阿克苏地区冬春茬日光温室番茄生产的适宜密度为3 000株/667m2(留5穗果),总产量最高,达到7 806.3 kg/667m2.  相似文献   

Comparison of accelerator mass spectrometry with gas chromatography for the determination of pesticide residues in individual items in the diets of wild birds and mammals     

Brown P  Garner C  Glass R  Ridgway C  Hart A 《Journal of agricultural and food chemistry》2004,52(12):3693-3701

Methods to refine the assessment of exposure of wild birds and mammals to pesticides required measurement of pesticide residues in very small samples of their diets. Sample sizes were in the 1-100 mg range, and the target residue for measurement was 0.01 mg/kg. Gas chromatography-mass spectrometry (GC-MS) with large volume injection was compared with the use of an accelerator mass spectrometer (AMS) to measure residues of pesticide labeled at near-background levels with carbon-14. The GC-MS method was able to detect residues down to 0.1 ng per item of diet, and the AMS detected the radiolabel down to 1 mBq (0.06 disintegration per minute, 1 ng of pesticide at the specific activity used) per sample. The target residue level was achieved by the GC-MS method for samples down to 10 mg. The GC method appeared to be best suited to monitoring residues in field studies, and the AMS shows great potential for use in laboratory experiments concerning pesticide degradation.  相似文献   

Enzyme-linked immunosorbent assay for screening aflatoxin B1 in cottonseed products and mixed feed: collaborative study     

D L Park  B M Miller  L P Hart  G Yang  J McVey  S W Page  J Pestka  L H Brown 《Journal of the Association of Official Analytical Chemists》1989,72(2):326-332

A joint AOAC/IUPAC (International Union of Pure and Applied Chemistry) interlaboratory study of an enzyme-linked immunosorbent screening assay (ELISA) for aflatoxins was conducted in laboratories in Canada, France, Japan, South Africa, Switzerland, The Netherlands, Tunisia, and the United States. Twenty-eight samples of raw and roasted peanuts, corn, whole cottonseed, cottonseed meal, ammoniated cottonseed meal, and poultry feed containing various quantities of natural aflatoxins and supplemented when appropriate with aflatoxin B1 were distributed to participating laboratories for testing. The assay is based on conjugation of pure aflatoxin B1 to an enzyme and the competition between this conjugate and (free) aflatoxins in the product for aflatoxin-specific antibodies coated onto microtiter well walls. After a wash step to remove all unbound aflatoxins, a substrate, added to each well, is catalyzed from a colorless to a green solution by any bound enzyme-conjugated aflatoxin B1 present. The intensity of the color decreases as the amount of free aflatoxin B1 in the product increases. Overall correlation was good between ELISA and thin-layer chromatographic (TLC) results for cottonseed products and mixed feed. Variable results were reported for corn and peanut product samples. Although some positive samples (greater than 15 ng/g) of cottonseed products and mixed feed were reported to contain less than 15 ng/g by visual determination, a review of data for absorbance measurements showed that the contamination level was close to the greater than or equal to 15 ng/g standard and would not have been reported as negative under routine screening.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

The correlation between in-situ,real-time aerosol photoemission intensity and particulate polycyclic aromatic hydrocarbon concentration in combustion aerosols     

K. M. Hart  St. R. McDow  W. Giger  D. Steiner  H. Burtscher 《Water, air, and soil pollution》1993,68(1-2):75-90

Aerosol photoemission (APE) has been found to be an excellent surrogate measure of particulate PAH concentration in combustion aerosols under a variety of laboratory and field conditions. Samples of oil stove, automobile exhaust, and urban air particulate matter were concurrently analyzed for aerosol photoemission intensity and particulate PAH concentration. In-situ, real-time analysis of the particulate matter was performed by UV-induced electron photoemission. Two photon energies, 4.9 and 6.7 eV, were chosen for irradiation. The latter energy was more sensitive and less selective. Particulate PAH concentrations were determined by collecting the particulate matter on a filter, solvent extracting the filter, and analyses of the extracts by gas chromatography / mass spectroscopy. Linear correlations (0.84≤r²≤1.00) were observed between aerosol photoemission intensities and the sum of particulate PAH concentrations for laboratory and field studies under a wide variety of conditions. The studies performed to date cover a dynamic range of three orders of magnitude (1 to 1000 ng / m³). The time resolution is in the order of a few seconds.  相似文献   

陕西省神木县2012年土地利用结构特征分析     

陈利利  张建军  张亭亭  郭敏杰  木热提江·阿不拉  蔺鹏飞  于艺鹏  张晓萍 《中国水土保持科学》2015,13(1):59-67

以位于晋陕蒙接壤区的陕西省神木县为例,选取相关定量指标,对其2012年土地利用结构特征进行分析,结果表明:1)神木县和各乡镇土地利用均以中低覆盖度草地为主,景观基质为草地。2)神木县土地利用类型齐全度低,集中化程度高,组合类型少,土地利用程度低;西北部风沙草滩区乡镇较东南部丘陵沟壑区乡镇土地利用类型齐全度高,集约化水平低,土地整体功能强,组合类型数多;乡镇间不同土地利用类型的区位意义与该乡镇的矿藏开发、风景名胜区、地形地貌和植被区系等有很大关系。3)神木县土地利用类型的空间结构表现出农地、居民地和工矿用地等受人类活动影响越强烈的地类,其分维数越小、形状指数越大、形状越简单的特征。因此,神木县未来土地利用需要增加有效植被盖度,进一步使陡坡农地退耕,加强未利用地的开发以及工矿用地复垦,改善县域生态环境,从而保证土地利用可持续发展。  相似文献   

3株塔克拉玛干沙漠藻的分子鉴定与分析     

依里夏提·地里夏提  艾山江  吾甫尔·米吉提 《安徽农业科学》2015,(18)

以从新疆塔克拉玛干沙漠中分离纯化的3株藻种为研究对象,研究温度和不同培养基对这3个品系生长的影响,并采用扫描电镜图和光学显微镜结合的方法对其形态进行初步鉴定,进一步采用18S r DNA基因数据对其进行分子鉴定。结果可以看出,Y1在20~30℃环境中都能生长,30℃生长最佳,最佳培养基为BG11培养基;Y2和Y3在改良型TAP培养基中生长最佳,它们的最适生长温度分别为25~30℃和30℃。利用Gen Bank中绿藻门不同科属种类序列的18S核糖体RNA,结合Olmos的文献,设计18S r DNA特异性引物进行PCR扩增。测序后经Blast对比、系统发育树及遗传距离分析,结合扫描电镜图和光学显微镜结果得知Y1为丝藻属、Y2为衣藻、Y3为绿球藻。  相似文献   

Effect of gonadectomy on subsequent development of age-related cognitive impairment in dogs.     

B L Hart 《Journal of the American Veterinary Medical Association》2001,219(1):51-56

OBJECTIVE: To determine whether gonadectomy predisposes dogs to development of age-related behavioral changes linked to cognitive impairment. DESIGN: Cohort study. ANIMALS: 29 sexually intact male dogs, 63 spayed female dogs, and 47 castrated male dogs 11 to 14 years old. PROCEDURE: Information on possible impairments in 4 behavioral categories linked to cognitive impairment (orientation in the home and yard, social interactions, house training, and sleep-wake cycle) was obtained from owners of the dogs by use of a structured telephone interview format. A second interview was performed 12 to 18 months after the initial interview, and differences in responses were evaluated. RESULTS: Sexually intact male dogs were significantly less likely than neutered dogs to progress from mild impairment (i.e., impairment in 1 category) to severe impairment (i.e., impairment in > or = 2 categories) during the time between the first and second interviews. This difference was not attributable to differences in ages of the dogs, duration of follow-up, or the owners' perceptions of the dogs' overall health. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the presence of circulating testosterone in aging sexually intact male dogs may slow the progression of cognitive impairment, at least among dogs that already have signs of mild impairment. Estrogens would be expected to have a similar protective role in sexually intact female dogs; unfortunately, too few sexually intact female dogs were available for inclusion in the study to test this hypothesis. There may be a need to evaluate possible methods for counteracting the effects of loss of sex hormones in gonadectomized dogs.  相似文献   

位于导体壁中的非圆截面等离子体的伸长度对等离子体稳定性的影响     

恰汗·合孜尔  冯波 《新疆农业大学学报》2006,29(4):66-69

通过引入Cap-cyclide坐标，针对位于导体壁中的非圆截面等离子体的任意伸长度，不使用任何近似的方法，求得了等离子体的稳定解析解。进而利用计算机对解析结果进行数值计算，分析和讨论了位于导体壁中的非圆截面等离子体的伸长度对等离子体稳定性的影响。  相似文献