共查询到20条相似文献，搜索用时 140 毫秒
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分析了混凝土结构常见的缺陷,详细介绍了传统加固方法;常规加固方法包括粘钢加固法、预应力加固法、外包钢加固法、置换加固法及间接加固法;新型加固方法包括绕丝加固法、粘贴钢筋加固法、玻璃钢筋加固法、玻璃钢加固法及碳纤维加固法;并对未来加固技术进行了展望. 相似文献
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本文用样线法对北京山区的灌草丛草地进行了测定。用并行指示种分析法、多元聚类法及传统分类法对其进行了分类,并对这三种方法对该类草地的分类结果进行了比较分析,结果说明并行指示种分析法较其余两种方法为好。 相似文献
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用HPLC-MS/MS研究动物毛发中克伦特罗的残留及代谢规律 总被引：4，自引：0，他引：4
研究建立了高效液相色谱-串联质谱(HPLC-MS/MS)测定毛发中盐酸克伦特罗残留的方法。猪毛发以0.1moL/L盐酸溶液提取,MCX固相萃取柱净化,流动相溶解定容。以SB-C18柱为分离柱,1%乙酸水溶液和甲醇(60∶40,V∶V)作为流动相,MS/MS进行定性和定量分析。在优化条件下的最低检出限为0.05μg/kg,定量限为0.2μg/kg。毛发样品中添加不同浓度盐酸克伦特罗,测得回收率在79.0%～86.2%之间,变异系数均低于15.2%。应用该方法研究了盐酸克伦特罗在猪毛发中的代谢并初步探讨其代谢机理。结果表明:在较高饲喂浓度(10mg/kg)时,用药5d后,黑色猪毛发有少量盐酸克伦特罗残留,而白色猪毛发中未检出。从第7天起猪毛发中盐酸克伦特罗蓄积量逐渐增加,最高蓄积浓度为4852.5μg/kg。 相似文献
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高效液相色谱-串联质谱法研究猪毛发中克仑特罗和莱克多巴胺的残留及代谢规律 总被引：1，自引：1，他引：0
建立了高效液相色谱-串联质谱(HPLC-MS/MS)同时检测猪毛发中克仑特罗和莱克多巴胺残留的方法。猪毛发经1 mol/L氢氧化钠溶液水解、乙酸乙酯萃取、MCX固相萃取柱净化,流动相溶解后用HPLC-MS/MS进行检测。克仑特罗在1.9～463.2 ng/mL浓度范围内线性关系良好(R2=0.999 0);回收率为83.3%～86.6%,相对标准偏差为6.7%～9.2%;检出限为0.3μg/kg,定量限为0.8μg/kg。莱克多巴胺在2.8～562.9 ng/mL浓度范围内线性关系良好(R2=0.999 2);回收率为83.4%～88.4%,相对标准偏差为7.2%～9.6%;检出限为0.4μg/kg,定量限为1.2μg/kg。应用该方法研究了克仑特罗、莱克多巴胺在猪毛发中的代谢规律并进行了猪毛发样品检测。结果喂药7 d至停药21 d猪毛发中均检出克仑特罗、莱克多巴胺残留;检测猪毛发样品25份,1份样品检出克仑特罗,残留量为58.68μg/kg。 相似文献
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β-激动剂克伦特罗在猪肝脏和肌肉组织中的残留 总被引：8，自引：0，他引：8
本文报道用高效液相色谱法检测β 肾上腺素能激动剂（克伦特罗Ｃｌｅｎｂｕｔｅｒｏｌ）在猪肝脏和背最长肌中的残留量。在肥育猪日粮中添加３ｍｇ／ｋｇ克伦特罗,试验期３０天,停药０、１、２、３、４天屠宰取肝脏和肌肉样。组织经匀浆浓缩提取,色谱条件为：ＣＬＣ ＯＤＳ色谱柱;以２０ｍｍｏｌ／ＬＫＨ２ＰＯ４＋３０μｍｏｌ／ＬＥＤＴＡ（ｐＨ３．９）乙腈＝８２１８（Ｖ／Ｖ）为流动相;紫外检测波长为２４３ｎｍ。结果表明,克伦特罗最低检测限为２ｎｇ／ｇ。停药当天（０天）肝脏和肌肉组织残留量分别为２０８．５ｎｇ／ｇ和１０．０ｎｇ／ｇ。停药后残留量迅速下降,肌肉在停药后第２天即检测不出,而肝脏要到第４天才检测不出。 相似文献
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气相色谱-质谱法同时测定猪肝中盐酸克伦特罗、莱克多巴胺残留 总被引：5，自引：1，他引：5
猪肝用乙酸乙酯、盐酸溶液提取后，经SCX固相萃取柱净化、BSTFA衍生化，定容后用气相色谱-质谱（GC／MS）外标法测定。测定结果表明：采用该方法，猪肝中盐酸克伦特罗和莱克多巴胺的检出限分别为0．3、1．0ng／g。盐酸克伦特罗在3．0～300ng／mL范围内与峰面积具有良好的线性关系，平均回收率为85．6％；莱克多巴胺在10～1000ng／mL范围内与峰面积具有良好的线性关系，平均回收率为76．6％。该方法简便可靠、干扰小、灵敏度高，可用作猪肝中克伦特罗和莱克多巴胺残留的同时测定。 相似文献
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克伦特罗检测方法研究进展 总被引：4，自引：0，他引：4
本文对β2肾上腺素受体激动剂克伦特罗的检测方法进行了综述,对各种方法优缺点作了简单地说明.其中酶联免疫分析法是目前克伦特罗最佳残留筛选检测法,高效液相色谱法、液相色谱-质谱法和气相色谱-质谱法是检测饲料及动物组织中克伦特罗残留的最终确认分析方法. 相似文献
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盐酸克伦特罗在羊主要脏器中残留量消除规律的研究 总被引：1，自引：0，他引：1
本试验对盐酸克伦特罗在休药期肉羊眼睛、心脏、肾脏、肺脏、脾脏等组织中的残留规律进行了研究。选择24头体重为(30±5)kg健康肉羊进行试验,在饲料中添加50 μg/kg盐酸克伦特罗,连续饲喂35 d后休药,通过液相色谱—质谱联用/质谱检测休药期肉羊组织中克伦特罗含量,研究其残留量消除规律。试验结果表明,肉羊眼睛中有高浓度的盐酸克伦特罗残留且其在肝脏中消除较慢;停药第14天眼睛中盐酸克伦特罗的浓度仍为42.42～63.48 μg/kg,脾脏中盐酸克伦特罗消除速度是最快的;停药3 d时,检测不到盐酸克伦特罗的残留量(低于检出限0.07 μg/kg),故眼睛可用作检测盐酸克伦特罗在肉羊生产上非法使用的靶标。 相似文献
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Harkins JD Robinson NE Woods WE Lehner AF Smith MD Gates RS Fisher M Tobin T 《Journal of veterinary pharmacology and therapeutics》2000,23(4):251-260
Clenbuterol, a beta2 agonist/antagonist, is the only bronchodilator approved by the US Food and Drug Administration for use in horses. The Association of Racing Commissioners International classifies clenbuterol as a class 3 agent, and, as such, its identification in post-race samples may lead to sanctions. Anecdotal reports suggest that clenbuterol may have been administered by intratracheal (IT) injection to obtain beneficial effects and avoid post-race detection. The objectives of this study were (1) to measure the pharmacological efficacy of IT dose of clenbuterol and (2) to determine the analytical findings in urine in the presence and absence of furosemide. When administered intratracheally (90 microg/horse) to horses suffering from chronic obstructive pulmonary disease (COPD), clenbuterol had effects that were not significantly different from those of saline. In parallel experiments using a behavior chamber, no significant effects of IT clenbuterol on heart rate or spontaneous locomotor activity were observed. Clenbuterol concentrations in the urine were also measured after IT dose in the presence and absence of furosemide. Four horses were administered i.v. furosemide (5 mg/kg), and four horses were administered saline (5 mL). Two hours later, all horses were administrated clenbuterol (IT, 90 microg), and the furosemide-treated horses received a second dose of furosemide (2.5 mg/kg, i.v.). Three hours after clenbuterol dose (1 h after hypothetical 'post-time'), the mean specific gravity of urine samples from furosemide-treated horses was 1.024, well above the 1.010 concentration at which furosemide is considered to interfere with drug detection. There was no interference by furosemide with 'enhanced' ELISA screening of clenbuterol equivalents in extracted and concentrated samples. Similarly, furosemide had no effect on mass spectral identification or quantification of clenbuterol in these samples. These results suggest that the IT dose of clenbuterol (90 microg) is, in pharmacological terms, indistinguishable from the dose of saline, and that, using extracted samples, clenbuterol dose is readily detectable at 3 h after dosing. Furthermore, concomitant dose of furosemide does not interfere with detection or confirmation of clenbuterol. 相似文献
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G. RE P. BADINO M. DACASTO F. DI CARLO C. GIRARDI 《Journal of veterinary pharmacology and therapeutics》1993,16(3):328-334
The effects of a 3-day intramuscular (i.m.) administration of clenbuterol (25 μ.g/ Kg), propranolol (12 mg/kg), clenbuterol (25 μg/kg) plus propranolol (12 mg/ Kg) and estradiol (0.5 μg) upon the female reproductive system were investigated in immature Sprague-Dawley rats. Clenbuterol and estradiol treatments induced a significant increase in uterus weight and in relative uterus weight, whereas in the groups treated with propranolol and clenbuterol plus propranolol no differences were detected versus controls. The uterine estrogen receptor levels were significantly increased by clenbuterol administration. In the rats dosed with propranolol and clenbuterol plus propranolol, no modifications occurred in estrogen receptor concentrations when compared with control values. Uterine progesterone receptors were never significantly affected by any of the considered treatments. Data obtained indicate that clenbuterol treatment induces an increase in uterus weight and in estrogen receptor levels and that these effects are regulated by acute beta-adrenergic stimulation, as the contemporaneous administration of high doses of a beta-blocker inhibit such effects. 相似文献