共查询到20条相似文献,搜索用时 125 毫秒
1.
采用碳化酸溶法消解环烷酸盐 ,其特点是采用了硝酸 ,高氯酸消解试样 ,消解速度快 ,且不发生爆炸。用本法测定环烷酸盐中的钴 ,方法快速 ,准确 ,效果良好 ,RSD为 0 5 7%。 相似文献
2.
用溶胶 凝胶法以磷钼酸 (MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2 催化剂 .使用ICP、XRD、TG DTA、IR、TPD MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能 .杂多钼酸盐与TiO2 通过O2 -在TiO2 表面发生了键合 .在 6 2 3K下 ,杂多阴离子仍保持原有的Keggin结构 .CO2 在Lewis酸位Ni(Ⅱ )和Lewis碱位Ni-O -Mo的桥氧协同作用下生成CO2 卧式吸附态Ni(Ⅱ )←O - (CO)← (O--Ni) .丙烯有多种吸附态在催化剂上吸附 .在 5 6 3K、1MPa和空速 15 0 0h-1的反应条件下 ,丙烯的摩尔转化率为 3.2 % ,产物MAA选择性为 95 % . 相似文献
3.
氢化物发生-原子荧光法研究天然水体中亚硒酸盐的微生物转化 总被引:4,自引:0,他引:4
用氢化物发生-原子荧光法测定天然水体中亚硒酸盐的微生物转化产物-单质硒Se°(S)的挥发态硒(Vse)。主要产物为单质硒,加入碳源促进亚硒酸盐的转化。 相似文献
4.
5.
6.
巴比妥类及其混合药物鉴定的谱学研究 总被引:1,自引:0,他引:1
本文用红外光谱、质谱对巴比妥类即巴比妥、烯丙异丙巴比妥、异戊比妥、速可眠、苯巴比妥标准混合药物进行了研究,为巴比妥类及其混合物组成的鉴定提供了快速、简化的有效分析方法,并对中毒实例进行了检测。 相似文献
7.
高效液相色谱法测定富马酸异哌丙吡仑 总被引:2,自引:0,他引:2
采用高效液相色谱法测定富马酸异哌丙吡仑的含量。色谱柱为 DIKMATMRPC18(4 .6 mm× 2 0 cm,5 μm) ,流动相为乙腈 - 0 .5 %十二烷基硫酸钠 -三乙胺 (5 5∶ 4 5∶ 0 .2 ) ,用冰醋酸调 p H值至 7.0± 0 .1;流速为 1.0 m L/ min,检测波长为 2 6 5 nm。该方法回收率为 99.8% ,RSD=0 .4 4%。富马酸异哌丙吡仑在浓度为0 .0 5 92 8— 0 .1383mg/ m L范围内线性关系良好。相关系数为 r=0 .9997。该方法操作简便 ,结果准确可靠。 相似文献
8.
WANG Li-ying XU Yan JIANG Zhen-dong XU Yong XIANG Sheng GUO Xin-yu WU Xue-min 《光谱学与光谱分析》2018,38(11):3401-3406
采用傅里叶变换红外光谱、X射线光电子能谱和扫描电子显微镜相结合的方式,从微观角度研究梳状聚羧酸盐分散剂在吡唑醚菌酯颗粒表面的吸附性能,为聚羧酸盐分散剂在吡唑醚菌酯悬浮剂中的应用提供理论依据。研究结果表明:吡唑醚菌酯吸附聚羧酸盐分散剂后,红外谱图未出现新的吸收峰,聚羧酸盐分散剂与吡唑醚菌酯之间主要是物理吸附,范德华力是聚羧酸盐分散剂与吡唑醚菌酯颗粒表面结合的主要作用力。吡唑醚菌酯颗粒吸附聚羧酸盐分散剂后,吡唑醚菌酯颗粒界面的N和Cl电子峰强度减弱,C和O电子峰强度明显增强,还出现了Na的电子峰,这主要是聚羧酸盐分散剂中C,O和Na的贡献,说明聚羧酸盐分散剂在吡唑醚菌酯颗粒表面形成了良好的吸附。并以Cl元素为特征元素,计算出聚羧酸盐分散剂在吡唑醚菌酯颗粒表面的吸附层厚度约为1.22 nm。用扫描电子显微镜研究了样品的形貌,吸附聚羧酸盐分散剂后,原本光滑的吡唑醚菌酯颗粒表面吸附了很多细小的颗粒,且有序分布,这是由于分散剂疏水集团对吡唑醚菌酯颗粒形成了包覆,亲水基团充分外露,从而有效阻止吡唑醚菌酯颗粒间的团聚,提高了吡唑醚菌酯悬浮剂的物理稳定性。 相似文献
9.
10.
11.
Inhaled corticosteroids (ICS) have become the prevalent treatment in asthmatics. Hazards to voice are under-recognized. A total of 38 patients with voice complaints associated with the use of ICS were assessed by 79 strobovideolaryngoscopy (SVL) examinations, 24 single and 14 multiple SVL. Hoarseness and dysphonia were the primary reasons for referral. The ICS initially used most frequently was Advair Diskus (fluticasone propionate and salmeterol-inhalation powder-[IP]) in 22 patients, followed by Flovent (fluticasone propionate inhalation aerosol-pressurized metered-dose inhaler-[PMDI]) in 11. Duration of ICS usage varied from 2 weeks to 4-5 years. Higher dosage and frequency of use exacerbated problems. Hazards to voice previously unrecognized by real-time indirect mirror or fiberoptic laryngoscopy were identified by meticulous attention to SVL abnormalities. There was essentially no difference in occurrence of abnormalities whether analyzed from the perspective of the initial 38 or all 79 examinations. These included abnormal mucosal wave symmetry/periodicity (76-63%), phase closure (74-63%), glottic closure (63-59%), mucosal wave amplitude/magnitude (50-35%), supraglottic hyperactivity (39-25%), mucosal quality (34-34%), and glottic plane (10-5%).Candidiasis of the larynx was infrequently observed. Fluticasone ICS were a cause of steroid inhaler laryngitis, and the best treatment was their avoidance or cessation. Further prospective studies ideally might include SVL documented as a pretherapy baseline and then repeated in each ICS patient who developed hoarseness/dysphonia. 相似文献
12.
J. Kadeřávek J. Kozempel M. Štícha J. Petrášek M. Jirsa P. Taimr L. Lešetický 《Czechoslovak Journal of Physics》2006,56(1):D711-D717
Two retinol derivatives, 4-[(131I)-4-iodobenzoyloxy]retinol propionate and 4-[(131I)-3-iodobenzylcarbamoyl]retinol propionate, were synthesized and their biodistribution in rats was studied in vivo by the whole body scintigraphy. 相似文献
13.
The structural transformations that occur when thermal treatments turn cerium propionate into nanocrystalline ceria have been
analysed with thermoanalytical techniques (TG, DTA and MS) and with structural and magnetic characterization (HRTEM, SQUID
and XRD) of the final and intermediate products. Attention has been paid to what occurs during the decomposition of propionate
and how the process is affected by the furnace atmosphere (oxidizing or inert). In an oxidizing atmosphere, the decomposition
of cerium propionate is triggered by the oxidation of Ce3+ to Ce4+. This reaction entails the loss of large unoxidized propionate fragments of the propionate ligands. As decomposition proceeds,
the carbonaceous residue makes the oxygen transport inside the material more difficult and decomposition becomes diffusion
limited. At this point, extensive oxidation of the residue begins until it is completely removed. Crystallization of CeO2 occurs simultaneously with decomposition. In these conditions, crystalline nanoparticles (diameter of 3–5 nm) can be obtained
at a temperature as low as 300 °C. In an inert atmosphere, decomposition occurs in three steps. During the first step, one
of the three propionate ligands is lost, with little oxidation of Ce3+, and is substituted by a hydroxyl group. The second step entails the loss of the remaining ligands with a substantial oxidation
of Ce3+ to Ce4+. After this step, the intermediate product is, proposed as, a mixture of amorphous Ce(OH)3 and Ce(OH)4. Finally, the third step leads to conversion of the Ce hydroxide into crystalline CeO2. In an inert atmosphere, the process is less reproducible than in air and a carbonaceous residue remains in the product. 相似文献
14.
Abstract In the forestomaches of ruminants the carbohydrates of the diet are transformed by microbiotic fermentation via pyruvate into short chain-fatty acids (acetate, propionate, and with less quantity butyrate). Since carbohydrates, i.e. glucose, cannot penetrate the rumen epithelium, metabolically needed glucose must be resynthesized intermediary mainly from propionate by gluconeogenesis. Lactose in milk of lactating cows is formed up to 98% from glucose of that origin [1]. Glucose absorption is possible in the small intestine, but contrary to monogastric animals, this is without quantitative relevance. Therefore, an experimentally found higher abundance of 13C in lactose of about 3‰, compared with milk-fat [2], is not explainable only by passing on the well known isotopic differences between carbohydrates and fat in the diet. According to the conclusion of De NIRO and EPSTEIN [3], who identified the decarboxylation of pyruvate to be the relevant step of 13C depletion in fat in cultures of Escheria coli, we assume an isotopic shift between propionate and acetate produced by the ruminal microorganisms using pyruvate as the last common precursor of both fatty acids. In vitro-investigation of 13C/12C - ratios in CO2 produced during the decarboxylation of pyruvate in fresh rumen-fluid, confirmed the responsibility of that enzyme-reaction for isotope fractionation also in the multiple-step-system of ruminal carbohydrate conversion. 相似文献
15.
Isa Illyas Md Sharif Sharifah Norain Mohd Hashim Norhayati Ghani Sulaiman Ab 《Ionics》2015,21(10):2949-2958
Ionics - A mercury(II) sensor was developed by using single-walled carbon nanotube (SWCNT) paste electrode modified with layered double Zn/Al hydroxide-3(4-methoxyphenyl)propionate nanocomposite... 相似文献
16.
以竹炭为固相萃取材料,建立了顺序注射在线微填充柱固相萃取分离富集痕量铋的方法,吸附在微填充柱上的铋(络合物)可用稀硝酸溶液(2.5 mol·L-1)洗脱回收.洗脱液与硼氢化钠溶液混合进行氢化物发生(HG)反应,氢化物经气液分离后与原子荧光(AFS)联用,或直接将洗脱液引入电感耦合等离子体质谱(ICP-MS),实现了对生... 相似文献
17.
Besides the enhancing effect caused by some anions, the depressing effect by formate, acetate, propionate and van-ad ate ions on the AA-determination of thallium at a relatively low temperature is presented. 相似文献
18.
基质固相分散高效液相色谱法检测河豚毒素 总被引:1,自引:0,他引:1
建立了河豚鱼肉中河豚毒素的基质固相分散萃取的提取方法,并采用高效液相色谱-二极管阵列检测器进行测定。通过样品前处理的优化,确立选取0.5g样品与2.0g阳离子交换(SCX)吸附剂混合研磨,并采用10mL 5%氨水:甲醇溶液(5:95,V/V)作为洗脱剂。经HPLC-PDA检测,结果表明,河豚毒素在1—100mg/L浓度范围内呈现良好的线性关系(R2=0.9990),检出限为3.8ng,定量下限为12.7ng;加标回收率为77.9%—108.1%,RSD为2.23%—5.45%。该方法操作简单、耗时少,符合河豚毒素分析检测的要求。 相似文献
19.
Tadahiro Nakamoto Motomi Katada Satoshi Kawata Susumu Kitagawa Hirotoshi Sano Michiko Konno 《Hyperfine Interactions》1994,93(1):1567-1572
Mixed-valence trinuclear iron propionates [Fe
2
III
FeIIO(C2H5CO2)6(py)3]npy, wheren=0, 1.5, were synthesized and the structure of the pyridine-solvated complex was determined by single-crystal X-ray diffraction. Mössbauer spectra of the solvated propionate complex showed a temperature-dependent mixed-valence state related to phase transitions, reaching an almost delocalized valence state at room temperature. On the other hand, the non-solvated propionate showed a remarkable change of the spectral shape related to a phase transition, remaining in a localized valence state at higher temperatures up to room temperature. 相似文献
20.
电感耦合等离子体-原子发射光谱法快速测定土壤中全硫 总被引:1,自引:0,他引:1
以王水溶样,电感耦合等离子体-原子发射光谱法快速测定土壤中全硫。方法检出限为0.03μg/g。对实际样品进行连续7次测定,方法精密度为1.18%—1.88%,回收率为97%—108%。经国家标准物质验证,结果与标准值相符。方法快速、准确。 相似文献