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排序方式: 共有105条查询结果,搜索用时 15 毫秒
91.
Aequationes mathematicae - Schauder’s fixed point theorem and the Banach contraction principle are used to study the polynomial-like iterative functional equation $$\begin{aligned} \lambda... 相似文献
92.
93.
Ivana Tatárová Avinash P. Manian Barbora Široká Thomas Bechtold 《Cellulose (London, England)》2010,17(5):913-922
Swelling of regenerated cellulose in nonalkali aqueous solutions containing lithium chloride and urea (LiCl/urea/water) was
examined. The effect of solution concentration on fiber properties was studied using microscopy, weight gain (swelling), and
mechanical strength tests. The regenerated cellulose samples included lyocell fibers, viscose fibers, and fibers spun from
alkali. The change in the mechanical properties of treated fibers was smaller than that of fibers treated with alkali to the
same level of swelling. The degree of swelling in these solutions was related to the propensity for the formation of Li–cellulose
coordination complexes, and these were enhanced by reductions in both urea and water content. 相似文献
94.
95.
Pyridazineshavebeenfoundwideapplicationinchemistryofpharmaceuticalsandagrochemicals"',thereforemethodsofdirectintroductionofsubstituentsintopyridazineringareofgreatinterest3.Pyridazinebelongstohighlyelectrophilicheterocycles,itundergoesvariousnucleop... 相似文献
96.
Gan TH Hutchins DA Carpenter PW Wright WM 《The Journal of the Acoustical Society of America》2003,114(2):759-766
This paper describes the use of air-coupled ultrasonic tomography for the simultaneous measurement of flow and temperature variations in gases. Air-coupled ultrasonic transducers were used to collect through-transmission data from a heated gas jet. A transducer pair was scanned in two-dimensional sections at an angle to the jet, and travel time and amplitude data recorded along various paths in counter-propagating directions. Parallel-beam tomographic reconstruction techniques allowed images to be formed of variations in either temperature or flow velocity. Results have been obtained using heated jets, where it has been shown that it is possible to separate the two variables successfully. 相似文献
97.
Let (G, ·) be a group, (H, +) be an abelian group, and ${f:G\rightarrow H}$ . The second order Cauchy difference of f is $$C^{(2)}f(x,y,z)=f(xyz)-f(xy)-f(yz)-f(xz)+f(x)+f(y)+f(z).$$ The functional equation $$C^{(2)}f(x,y,z)=0$$ is studied. We present its general solution on free groups. Solutions on other selected groups are also given. 相似文献
98.
Lijun Liu Siva Krishna Karuturi Liap Tat Su Qing Wang Alfred Iing Yoong Tok 《Electrochemistry communications》2011,13(11):1163-1165
An electrochromic photonic crystal (EPC) display device that combines chemical (electrochromic) and physical (photonic) coloring mechanisms is reported for the first time. This EPC exhibits superior and versatile color tunability. The TiO2 inverse opals fabricated by atomic layer deposition are adopted as EPC material. Results show that the photonic band gaps selectively modified the optical properties of the EPC and enabled facile tuning of electrochromic colors. In addition, the reversible photonic and photonic modified electrochromic coloring states with insertion/extraction of lithium ions enable novel and promising approaches for future display applications. 相似文献
99.
Necdet Coşkun Fatma Tirli Tat 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):881-886
1,3-Dipolar cycloaddition of imidazoline 3-oxides 1 with methylisothiocyanate proceeds regio- and diastereoselectively to give tetrahydroimidazo[1,5- b ][1,2,4]oxadiazol-2(1 H )-thiones 3 in high yields. The cis configuration of the adducts were proved by our double cis elimination test as well as by NOESY experiments. The imidazooxadiazol-2-thiones 3a-e were treated with concentrated HCl in ethanol at 50°;C to give the corresponding 4 H -[1,2,4]oxadiazole-5-thione only in the cases where the substituent at C-6 is an aryl. 相似文献
100.
The development of reference material for four organochlorine pesticides, namely hexachlorobenzene and three isomers of hexachlorocyclohexane (alpha-hexachlorocyclohexane, beta-hexachlorocyclohexane and gamma-hexachlorocyclohexane), in a ginseng root sample is presented. Raw materials (Panax ginseng) were purchased from a local market and confirmed to contain certain levels of incurred organochlorine pesticide residues by a validated gas chromatography-mass selective detection method. A total of more than 300 bottles each containing 25 g of samples were prepared after the materials had been freeze-dried, milled and thoroughly mixed. The homogeneity and stability of samples from randomly selected bottles were verified and the reference values were characterized using a highly precise isotope dilution gas chromatography-mass spectrometry (ID-GCMS) method that was recently developed by our laboratory. The purity of standard organochlorine chemicals was determined against certified reference materials to establish the accuracy of the ID-GCMS analysis. The concentrations (+/- expanded uncertainty) of hexachlorobenzene, alpha-hexachlorocyclohexane, beta-hexachlorocyclohexane and gamma-hexachlorocyclohexane in the reference material were 0.198 +/- 0.015, 0.450 +/- 0.022, 0.213 +/- 0.011 and 0.370 +/- 0.032 mg kg(-1), respectively. A portion (70 bottles) of the samples was also used in a proficiency testing (PT) scheme for assessing the testing capabilities of field laboratories. The consensus mean values of the PT obtained from the 70 participants were on the same order but deviated by -2.7 to -14.1% from those of the assigned reference values. Because of the wide spread of participants' data (relative standard deviation ranging from 44 to 56%), the PT results were not included in the calculation of the assigned values of the reference materials. The materials served as suitable reference materials to ascertain the quality control and validation processes for the determination of organochlorine pesticides in herbal matrices. 相似文献