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1.
Using the polyglycol gel method, a series of Pr2 − x
SrxCoO4 ± y
(0.2 ≤ x ≤ 1.0) mixed oxides were prepared, and their catalytic activities were studied in the test reaction of NO reduction by CO.
The solid-state physicochemical properties, including crystal structure, defect structure, IR spectrum, valence state of B-site
ions, nonstoichiometry oxygen (y), oxygen species, and redox properties, were characterized by means of XRD, IR, TPD, TPR,
XPS, and chemical analysis. The results show that all mixed oxides display a K2NiF4 structure. When x = 0.2 and 1.0, the obtained samples still have little uncertain mixed oxides; however, the mixed oxides (x = 0.4, 0.6, 0.8) all represent a single A2BO4 phase. With the increase of x, lattice parameters, unit-cell volume, and average crystalline size decrease gradually, whereas microstrain density, the
concentration of Co3+, the amounts of lattice oxygen released and the concentration of oxygen vacancy increase. The catalytic activities of Pr2 − x
SrxCoO4 ± y
catalysts for NO reduction by CO are closely correlated with oxygen vacancy and the concentration of Co3+.
Published in Russian in Kinetika i Kataliz, 2006, Vol. 47, No. 3, pp. 431–437.
The text was submitted by the authors in English. 相似文献
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基于密度泛函理论研究了非对称双笼型单分子溶剂化电子e-@C24F22(NH)2C20F18(1、2 和3), 进一步展示了我们提出的一种新型电子异构体——(非对称型的)笼间电子迁移异构体. 1、2 和3 具有显著不同的偶极矩. 由于都存在两个氧化还原中心, 它们属于一种非金属型的新型Robin-Day II-III 分子. 对于1 和3, 额外电子分别定域在C24F22和C20F18笼里(Robin-Day II); 对于2, 额外电子则离域于两个非对称的笼中(Robin-Day III). 值得注意的是, 在y 轴方向上外加-0.0004和-0.0008 a.u.的临界电场(Ec)时可分别使1 的额外电子从C24F22笼中部分和全部地迁移到C20F18笼中, 即实现从1 到2 再到3 的转化; 当Ec为0.0004 a.u.时, 3 的额外电子从C20F18笼中全部迁移到了C24F22笼中, 即3 未经过2 直接转化成了1. 相似文献
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使用SAC/SAC-CI和D95++, 6-311++g, 6-311++g**及D95(d)基组, 分别对BF分子的基态X1Σ+、第一简并激发态A1Π和第二激发态B1Σ+的平衡结构和谐振频率进行优化计算. 对所有计算结果进行比较, 得出6-311++g**基组为最优基组. 运用6-311++g**基组和SAC方法对基态X1Σ+, SAC-CI方法对激发态A1Π和B1Σ+进行单点能扫描计算, 并用正规方程组拟合Murrell-Sorbie函数, 得到相应电子态的势能函数解析式, 由得到的势能函数计算了与X1Σ+, A1Π和B1Σ+态相对应的光谱常数, 结果与实验数据较为一致. 相似文献
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Xiaochun Zhou Xiaojun Wang 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(13):2033-2036
A modified low temperature solid state process has been proposed to systematically synthesize europium-doped yttrium phosphate-vanadates with general formula Y0.48Li1.5V1 ? x P x O4:Eu3+ (x = 0.2, 0.4, 0.6). All the Y0.48Li1.5V1 ? x P x O4:Eu3+ products were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The excitation and emission spectra were measured at room temperature. Y0.48Li1.5V1 ? x P x O4:Eu3+ show the characteristic missions of Eu3+ (5 D 0?7 F 1, 2, 3, 4 transitions dominated by 5 D 0?7 F 2), intensities of the products were sensitive to the x value, and the x value had an obvious influence on the (5 D 0?7 F 2)/(5 D)0?7 F 1) intensity ratio of Eu3+. In addition, incorporation of Li+ ions in the phosphors reduce the amount of Y2O3, lower the cost of production, and cause a new phase Li3VO4. 相似文献
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An unprecedented 4f-5d material(La6Hg5Br26)[4(HgBr2)](2Br)(1)was syn-thesized by hydrothermal reactions and structurally characterized by single-crystal X-ray diffraction method.Complex 1 crystallizes in the Pbam space group of orthorhombic system with a=13.0980(10),b=13.6650(9),c=28.010(2)?,V=5013.4(6)?^3,Br36Hg9La6,Mr=5515.53,Z=2,Dc=3.613 g/cm^3,μ(MoKα)=29.457 mm^–1 and F(000)=4598.Compound 1 is characteristic of a two-dimensional(2D)layered structure.The photoluminescent measurements with solid-state samples reveal that compound 1 has a strong emission in the green region of light spectrum.It has remarkable CIE chromaticity coordinates of(0.2499,0.3589).A wide optical band gap of 3.41 eV is discovered by the solid-state UV/vis diffuse reflectance spectrum.The variable-temperature magnetic susceptibility obeys the Curie-Weiss law(cm=c/(T–q))with C=2.48 K and a negative Weiss constantθ=–169.07 K as revealed by the magnetic measurements,indicating the existence of an antiferromagnetic interaction in compound 1. 相似文献
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以烟酰胺和硝酸铕为原料,采用热溶剂法合成了烟酰胺-铕配合物的微纳米球。其结构和性能经红外光谱(IR)、热重(TG)、扫描电镜(SEM)、X-射线衍射(XRD)、元素分析(EDS)和荧光检测等表征。研究结果表明:配合物含有碳、氧、氮和铕等元素,其红外光谱图与烟酰胺配体有明显的差异;配合物的质量在250℃和550℃条件下出现了明显的下降,下降率分别为15%和19%; SEM照片显示配合物为大小不均一的微纳米球,且具有较好的荧光发光性能,发射峰位于579 nm, 591 nm, 612 nm, 618 nm, 693 nm和699 nm。烟酰胺配体和烟酰胺-铕配合物对肺癌人肺泡基底上皮细胞(A549细胞)的活性影响趋势一致,随着药物浓度升高,该细胞活性没有发生明显变化。 相似文献
9.
《Surface science》1989,220(1):L657-L666
The various modes of hydrogen uptake exhibited by Nd overlayers and Nd/Cu ultra thin alloy films on Cu(100) have been investigated by LEED, UPS, XPS and thermal desorption measurements. Ultra thin Nd overlayers exhibit very low sticking probabilities for H2 (~10−4) — far lower than the values characteristic of thick Nd films. This behaviour is associated with the unusual surface structure adopted by the rare earth when present as a very thin film. Codeposition of Nd and H2 leads to the formation of sorbed hydrogen and is accompanied by valence charge transfer from Nd to H. The kinetics of H2 desorption from alloy films and Nd overlayers are markedly different: this feature provides a sensitive test for the overlayer → alloy transformation. 相似文献
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