一个长方体的长、宽、高分别是3x-4，2x和x，则它的体积等于（　　）
(3x-4)o2x=3x3-4x3
C．（3x-4）o2xox=6x3-8x2
D．2x（3x-4）=6x2-8x
根据题意得：（3x-4）o2xox=6x3-8x2；故选C．
试题“一个长方体的长、宽、高分别是3x-4，2x和x，...”；主要考察你对
等知识点的理解。
如下表所示，表中各方程是按照一定规律排列的．（1）解方程1，并将它的解填在表中的空白处：
6（x-2）-x=x（x-2）
x1=______，x2 =______
8（x-3）-x=x（x-3）
x1=4，x2 =6
10（x-4）-x=x（x-4）
x1=5，x2 =8
（2）若关于x的方程a（x-b）-x=x（x-b）（a＞6）的解是x1=6，x2=10，求a，b的值．该方程是不是（1）中所给出的一列方程中的一个方程？如果是，它是第几个方程？（3）请写出这列方程的第n个方程的解，并验证所写的解．
已知关于x的方程x2-ax-3a=0的一个根是-2，则它的另一个根是______；a=______．
若x=2是方程x2-3x+q=0的一个根．则q的值是______．
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旗下成员公司Join ResearchGate to access over 30 million figures and 100+ million publications – all in one place.Copy referenceCopy captionEmbed figurePublished in
Article & Jul 2013
& Berichte der deutschen chemischen Gesellschaft
+8 more authors...
ABSTRACT: Reactions in solvothermal conditions between hexanuclear rare earth complexes and H2bdc, where H2bdc symbolizes terephthalic acid, lead to a family of monodimensional coordination polymers in which hexanuclear complexes act as metallic nodes. The hexanuclear cores can be either homometallic with general chemical formula [Ln6O(OH)8(NO3)6](2+) (Ln = Pr-Lu plus Y) or heterometallic with general chemical formula [Ln6xLn'6-6xO(OH)8(NO3)6](2+) (Ln and Ln' = Pr-Lu plus Y). Whatever the hexanuclear entity is, the resulting coordination polymer is iso-structural to [Y6O(OH)8(NO3)2(bdc)(Hbdc)2·2NO3·H2bdc]∞, a coordination polymer that we have previously reported. The random distribution of the lanthanide ions over the six metallic sites of the hexanuclear entities is demonstrated by (89)Y solid state NMR, X-ray diffraction (XRD), and luminescent measurements. The luminescent and colorimetric properties of selected compounds that belong to this family have been studied. These studies demonstrate that some of these compounds exhibit very promising optical properties and that there are two ways of modulating the luminescent properties: (i) playing with the composition of the heterohexanuclear entities or (ii) playing with the relative ratio between two different hexanuclear entities. This enables the independent tuning of luminescence intensity and color.Article · May 2013 +1 more author...ABSTRACT: The luminescent properties of two families of heteronuclear lanthanide-containing coordination polymers are compared. These families have general chemical formulas [Ln2-2xLn'2x(ip)3(H2O)9·6H2O]∞ and [Ln2-2xLn'2x(aip)2(H2O)10·(aip)·4H2O]∞ where H2ip and H2aip stand for isophthalic acid and 5-amino-isophthalic acid, respectively, and where Ln and Ln' are one of the lanthanide ions between Sm(3+) and Dy(3+). Heteronuclear compounds that belong to each family are isostructural to the already reported homonuclear compounds [Gd2(ip)3(H2O)9·6H2O]∞ and [Eu2(aip)2(H2O)10·(aip)·4H2O]∞, respectively. These two crystal structures are very similar. However, despite similar chemical formulas, similar crystal structures, and similar hydration rates, these two families of compounds present very different luminescent properties that have thus been deeply investigated. This study demonstrates that these different optical behaviors can be attributed to the presence of a PET (photoinduced electron transfer) mechanism that is only present in the amino-isophthalate-containing coordination polymers.Article · Jan 2014 +1 more author...ABSTRACT: Reactions in water at room temperature between lanthanide ions and 5-hydroxy-1,3-benzene-di-carboxylic acid hereafter referred to as H2(hip) lead to a new family of lanthanide-based hetero-nuclear compounds with the general chemical formula [Ln2-2xLn2x′(hip)2(H2O)10,(hip),4H2O]∞ where Ln and Ln′ = Pr–Lu or Y and where 0 ≤ x ≤ 1. The physico-chemical properties of this family have been characterized by PXRD, TDXD, TG/TD, EDS, SEM, 89Y solid state NMR spectroscopy and optical spectroscopy. The luminescent properties of these compounds are studied in detail. This study reveals that the competition between intermetallic energy transfer and photo-induced electron transfer gives rise to complex multiple emission spectra. It is therefore possible, for some Ln/Ln′ compositions, to obtain green, yellow or red emission by tuning the excitation wavelength over a 50 nm range. From a global point of view, this study shows that this series of compounds could be of great interest as far as luminescent coordination polymers usable as taggants for the fight against counterfeiting are aimed.Article · Jun 2014 +1 more author...ABSTRACT: Because of their remarkable and unmatched optical and magnetic properties, the lanthanides are under the limelight when it comes to high technology. These elements are used in strategic applications such as optical glasses and lasers, telecommunications, lighting and displays, magnetic materials, hard-disk drives, security inks and counterfeiting tags, catalysis, biosciences, and medicine, to name but a few. Long considered as minor actors in transition-metal chemistry, they have now gained respect from coordination chemists who insert them into sophisticated functional and polyfunctional molecules and materials.
This minireview focuses on trivalent lanthanide ions and first summarizes first their basic properties. Then some classical aspects of their coordination chemistry are discussed, followed by macrocyclic chemistry, supramolecular chemistry and self-assembly processes. The last part of this contribution deals with coordination polymers and hybrid materials including potential applications.Article · Sep 2014 ABSTRACT: Luminescent lanthanide coordination polymers composed of lanthanide ions and organic joint ligands exhibit characteristic photophysical and thermostable properties that are different from typical organic dyes, luminescent metal complexes, and semiconductor nanoparticles. Various types of luminescent Eu(III) and Tb(III) coordination polymers have been reported to date. One-, two-, and three-dimensional alternating sequences of lanthanide ions and organic ligands exhibit remarkable characteristics as novel organic materials with various structures, and unique physical properties. In this review, the characteristic structures, photophysical properties, and photonic applications for organic display devices, triboluminescent materials, thermosensors, color and brightness tuning, new type organogels, future magneto-optical materials, luminescent organo-nanoparticles, and energy transfer process of lanthanide coordination polymers are introduced.Article · Nov 2014 ABSTRACT: A strategy to achieve the ratiometric thermometer by encapsulating luminescent perylene dye into the pores of an europium MOF is developed. The resulting MOF?dye thermometer exhibits highly temperature-dependent luminescence intensity ratio over the physiological temperature range, with a maximum sensiti-vity of 1.28% °C(-1) at 20 °C.
(C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Article · Jan 2015 +1 more author...
oror log in with3 - 4W tol = 1E – 4 ∫5 (2x2 + 3x + 4...
3 - 4 W tol = 1E – 4 ∫5 (2x2 + 3x + 4) dx1 f (x) AK4 CALC 4 ∫dx cvx+dv+e, b,f, bE-)w o f (x) X A Z, r, θ o – tol n tol 1E – 5 n o k o ∫b d f (x) dx + ∫ g (x) dxa c o b 2 × ∫ b f (x) dx log( a ∫ f (x) dxa o f(x), a, b, n ∫cos 0.5 (sin x + cos x) dx = sin 0. ∫ (sin x + cos x, sin 0.5 + cos 0.5, 5)5 o Σ 61
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我取消屏蔽了下列各一元二次不等式中，解集为空集的是
A．x2－2x+3&0
B．(x+4)(x－1)&0
C．(x+3)(x－1)&0
D．2x2－3x－2&0
试题“下列各一元二次不等式中，解集为空集的是
...”；主要考察你对
等知识点的理解。
下列说法“①任意两个正方形必相似；②如果两个相似三角形对应高的比为4：5，那么它们的面积比为4：5；③抛物线y=-（x-1）2+3对称轴是直线x=1，当x＜1时，y随x的增大而增大；④若
；⑤一元二次方程x2-x=4的一次项系数是-1；⑥
不是同类二次根式”中，正确的个数有（　　）个
请写出一个符合下列条件的一元二次方程：①有两个不相等实数根；②其中有一个解为x=1______．
已知y=mxm2-2m+2是关于x的二次函数，则m的值为______．
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