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排序方式: 共有362条查询结果,搜索用时 15 毫秒
271.
以CuZnAl复合氧化物为催化剂,以空气为氧化剂,在固定床反应器中进行了模拟汽油中正戊硫醇的催化空气氧氧化脱除反应.考察了空速、氧气/硫比和反应温度等因素对脱除正戊硫醇效果的影响.结果表明,正戊硫醇的脱除可以在重时空速为50~70h-1,反应温度为150和300℃下高效地进行,在100h内正戊硫醇的转化率维持在90%以上.正戊硫醇氧化在150℃下发生二聚生成二聚物;在300℃下反应初期以深度氧化生成SO2为主,但随着反应时间的延长深度氧化反应逐渐减弱而二聚反应逐渐增强. 相似文献
272.
火焰原子吸收光谱法对铁扫帚根中六种微量元素的测定 总被引:2,自引:0,他引:2
用火焰原子吸收光谱法直接测定了铁扫帚根Fe、Cu、Mg、Ca、Mn、Zn 6种微量元素。结果表明,所测定的铁扫帚中含有丰富的人体必需微量元素,采用此法回收率在96.0%~106.0%之间,方法简单、准确,结果令人满意。 相似文献
273.
Yunpeng Xu Pingwei Cai Kai Chen Qingsong Chen Prof. Dr. Zhenhai Wen Prof. Long Chen 《Angewandte Chemie (International ed. in English)》2023,62(18):e202215584
Covalent organic frameworks (COFs), thanks to their adjustable porous structure and abundant build-in functional motifs, have been recently regarded as promising electrode materials for a variety of batteries. There still remain grand opportunities to further utilizing their merits for developing advanced COFs-based batteries. In this paper, we propose a hybrid acid/alkali all-COFs battery by coupling pyrene-4,5,9,10-tetraone based COF cathode with anthraquinone based COF anode. In such a hybrid acid/alkali all-COFs battery, the cathodic COF favorably works in acid with a relatively positive potential, while the anodic COF preferably runs in alkali with a relatively negative potential. It thus can deliver a decently high discharge capacity of 92.97 mAh g−1 with a wide voltage window of 2.0 V, and exhibit high energy density of 74.2 Wh kg−1 along with a considerable cyclic stability over 300 cycles. The development of the proof-of-concept all-COFs battery may drive forward the improvement of newly cost-effective and performance-reliable energy storage devices. 相似文献
274.
Wu Qingsong 《Acta Mechanica Sinica》1988,4(3):239-247
In this paper, the random choice method (RCM) with an operator-splitting technique is applied to the numerical simulation
of shock propagation down a tube of changing area with a nonuniform steady flow and the flow properties behind the shock.
The change rules of the shock strength and flow properties behind it are obtained, and the results are analysed. 相似文献
275.
Shangyou Zhang Zhimin Zhang Qingsong Zou 《Numerical Methods for Partial Differential Equations》2017,33(6):1859-1883
We propose a local postprocessing method to get a new finite element solution whose flux is conservative element‐wise. First, we use the so‐called polynomial preserving recovery (postprocessing) technique to obtain a higher order flux which is continuous across the element boundary. Then, we use special bubble functions, which have a nonzero flux only on one face‐edge or face‐triangle of each element, to correct the finite element solution element by element, guided by the above super‐convergent flux and the element mass. The new finite element solution preserves mass element‐wise and retains the quasioptimality in approximation. The method produces a conservative flux, of high‐order accuracy, satisfying the constitutive law. Numerical tests in 2D and 3D are presented.© 2017 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 33: 1859–1883, 2017 相似文献
276.
建立了用凝胶渗透色谱(GPC)去脂、气相色谱-负化学电离源-质谱(GC-NCI-MS)测定人乳中多溴联苯醚(PBDEs)、德克隆(DP,包括syn-DP和anti-DP)、五溴甲苯(PBT)、六溴苯(HBB)和多氯联苯(PCBs)的方法。人乳样品中加入内标13C12-BDE-139、13C12-BDE-209、13C10-syn-DP、13C12-PCBs(13C12-CB-81,77,123,118,114,105,126,167,156,157,169,189),空白样品还额外加入PBT和HBB,经过加酸去蛋白质、液液萃取、GPC去脂、酸性硅胶柱净化后,定量测定。人乳样品中13C12-BDE-139、13C12-BDE-209、13C10-syn-DP、13C12-PCBs的加标回收率分别为112.9%±14.0%、99.3%±12.7%、80.5%±17.9%、64.6%±2.4%,空白样品中PBT和HBB的加标回收率分别为102.8%±18.0%和88.1%±14.4%,各卤代化合物检出限范围为0.33~333.3pg/m L。应用本方法对人乳样品进行检测,均没有检出CB-77,81,169、BDE-154,85、syn-DP、anti-DP。∑9PCBs(CB-123,118,114,105,126,167,156,157,189)、∑8PBDEs(BDE-28,47,100,99,153,183,190,209)、PBT、HBB浓度范围分别为:0.11~0.22、4.9~7.9、0.0037~0.0056和0.0053~0.021ng/m L。 相似文献
277.
278.
279.
NUMERICAL SIMULATION OF PARTICLE MOTION IN TURBO CLASSIFIER 总被引:3,自引:0,他引:3
Ning xu Guohua Li Zhichu Huang 《中国颗粒学报》2005,3(5):275-278
Research on the flow field inside a turbo classifier is complicated though important. According to the stochastic trajectory model of particles in gas-solid two-phase flow, and adopting the PHOENICS code, numerical simulation is carried out on the flow field, including particle trajectory, in the inner cavity of a turbo classifier, using both straight and backward crooked elbow blades. Computation results show that when the backward crooked elbow blades are used, the mixed stream that passes through the two blades produces a vortex in the positive direction which counteracts the attached vortex in the opposite direction due to the high-speed turbo rotation, making the flow steadier, thus improving both the grade efficiency and precision of the turbo classifier. This research provides positive theoretical evidences for designing sub-micron particle classifiers with high efficiency and accuracy. 相似文献
280.