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911.
Determination of bioavailable fractions of Zn, Cu, Ni, Pb and Cd in soils and sludges by atomic absorption spectrometry 总被引:1,自引:0,他引:1
The single extraction procedures validated by the standards, measurement and testing programme (formerly BCR), extraction with 0.05 mol l−1 EDTA and 0.43 mol l−1 acetic acid, have been applied to reference materials of soils and sludges with certified total values of elements, in order to determine bioavailable contents of Cd, Cu, Ni, Pb and Zn. These soils, which represent uncontaminated pedologically different types of soils from Slovakia and sludges from city water treatment are characterized for the bioavailable fraction of the metals using the procedures followed by SM&T Programme. Concentrations of the elements under the study in the extracts were determined by flame (FAAS) using calibration curves in appropriate extractants and by electrothermal (ETAAS) atomic absorption spectrometry, using technique of standard additions for the evaluation of the results. The accuracy of the extraction procedures and determinations of the elements in the extracts was controlled using CRM 483 certified for EDTA- and acetic acid-extractable contents of Cd, Cu, Ni, Pb and Zn in sewage sludge amended soil. 相似文献
912.
1 INTRODUCTION Cyanide, CN, is an important free-radical mole-cule of one carbon chemistry, organic chemistry, free-radical chemistry and cosmochemistry. And the im-portant industrial processes, such as the Andrussovreaction, depend on the reactivity of CN bond[1]. Thechemistry of cyanide is also important in the surfacechemistry of a number of C- and N-containing sys-tems[1, . During the past decade, the adsorption of 2]CN and CN-containing molecules on transition metalsurfa… 相似文献
913.
Two kinds of complexes [Ni(DETA)2]3[SiNiW11O39]·2.5H2O (DETA=diethylenetriamine) (1) and [H2en]2[Ba0.15(H2O)2(Hen2)]H1.7[SiNaW11O39]·2H2O (2) were obtained from the hydrothermal reaction and characterized by single crystal X-ray diffraction analysis and IR spectra. Crystal data: C24H83N18Ni4O41.5SiW11 (1), monoclinic, Pn, a=10.926(2) Å, b=23.022(5) Å, c=13.221(3) Å, β=94.27(3)°, V=3316.4(11) Å3, Z=2; C8H46.7N8Ba0.15NaO43SiW11 (2), monoclinic, P21, a=12.840(3) Å, b=11.174(2) Å, c=16.693(3) Å, β=91.14(3)°, V=2394.4(8) Å3, Z=2. Both of them consists of one mono-substituted Keggin unit [SiMW11O39](8−n)− (MNi, Na, n=2, 1) obtained by metal atom substituting for a W atom from the plenary anion [SiW12O40]4−. This unit then connects with other adjacent units via M-O-W bridges constructing an infinitely one-dimensional chain-like structure in which the metal cation and polyanion alternate. Moreover, both of Ni or Na atoms are in a distorted octahedral environment with six oxygen atoms and occupy one position in the oxometalate shell of the Keggin structure. 相似文献
914.
Wiesława Ferenc Agnieszka Walków-Dziewulska Maria Wojciechowska J. Sarzyński 《Journal of Thermal Analysis and Calorimetry》2006,86(2):359-364
Physico-chemical properties of 4-chloro-2-nitrobenzoates of Co(II),
Ni(II), and Cu(II) were studied. The complexes were obtained as mono- and
trihydrates with a metal ion to ligand ratio of 1:2. All analysed 4-chloro-2-nitrobenzoates
are polycrystalline compounds with colours depending on the central ions:
pink for Co(II), green for Ni(II), and blue for Cu(II) complexes. Their thermal
decomposition was studied only in the range of 293–523 K, because it
was found that on heating in air above 523 K 4-chloro-2-nitrobenzoates decompose
explosively. Hydrated complexes lose crystallization water molecules in one
step and anhydrous compounds are formed. The final products of their decomposition
are the oxides of the respective transition metals. From the results it appears
that during dehydration process no transformation of nitro group to nitrite
takes place. The solubilities of analysed complexes in water at 293 K are
of the order of 10–4–10–2
mol dm–3. The magnetic moment values of Co2+,
Ni2+ and Cu2+ ions in
4-chloro-2-nitrobenzoates experimentally determined at 76–303 K change
from 3.89 to 4.82 μB for Co(II) complex, from 2.25
to 2.98 μB for Ni(II) 4-chloro-2-nitrobenzoate,
and from 0.27 to 1.44 μB for Cu(II) complex. 4-chloro-2-nitrobenzoates
of Co(II), and Ni(II) follow the Curie–Weiss law. Complex of Cu(II)
forms dimer. 相似文献
915.
将Ni(teta)(ClO4)2 (teta=5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane)的DMF溶液和K3[Fe(CN)6]的水溶液在填充了琼脂冻胶的U型管中通过扩散反应, 得到了标题化合物(H2teta)2{[Ni(teta)][Fe(CN)6]2}•17H2O, 该化合物晶体属三斜晶系, 空间群P1, 晶胞参数为a=0.9998(2) nm, b=1.5514(3) nm, c=1.6647(4) nm, α=114.15(2)°, β=100.91(2)°, γ=93.42(2)°, V=2.2863(10) nm3, z=1, Dc=1.196 g•cm-3, F(000)=890, μ=5.84 cm-1, GOF=0.894, R1=0.0582, wR2=0.1446 [I>2σ(I)]. 该化合物的基本单元由2个[H2teta]2+阳离子、1个{[Ni(teta)][Fe(CN)6]2}4-阴离子和17个水分子组成, 它们之间通过N—H…N氢键而形成具有二维平面结构的超分子化合物. 1.8~300 K变温磁化率研究表明, 化合物中三核体系Fe (s=1/2)-Ni (s=1)-Fe (s=1/2)中心原子间通过氰基桥联而发生强的铁磁相互作用, 磁参数J=4.33 cm-1, g=2.6, θ=60 K. 通过TG-DTG测定了配合物的热稳定性. 相似文献
916.
Ni/Al2O3催化剂上甲烷三重整制合成气 总被引:3,自引:4,他引:3
制备了负载于大孔容、高比表面的γ-Al2O3载体上的Ni基催化剂.采用固定床流动反应装置,考察了催化剂焙烧温度、反应条件(反应温度、压力、空速以及反应原料气组成)对甲烷三重整反应(TRM)制合成气的催化性能的影响.结果表明,650℃焙烧的催化剂具有较好的稳定性.在常压、850℃、10080h-1、n(CH4)/n(CO2)/n(H2O)/n(O2)=1/0.48/0.54/0.1的条件下,CH4转化率达到95.4%,CO2转化率达到84.6%,在此条件下连续运行9h未见活性下降.TRM反应适宜于在高温、低压下进行,原料组成的变化不会影响CH4转化率,但会影响CO2转化率和产物合成气的n(H2)/n(CO)比. 相似文献
917.
Ni2P/TiO2的制备及其对苯加氢反应的催化性能 总被引:2,自引:1,他引:2
采用程序升温还原方法制备了TiO2负载的晶态Ni2P催化剂。用X射线衍射(XRD)及低温N2吸附(BET)等技术对样品的物相、比表面积等性质进行了表征。以苯气相加氢为模型反应考察了Ni2P/TiO2催化剂加氢性能,并对Ni2P负载量、前驱体中P的质量分数对催化剂的物相及性能的影响进行了研究。实验结果表明, TiO2负载的晶态磷化镍催化剂上,Ni2P是主要物相。Ni2P/TiO2催化剂对苯加氢反应具有较高的活性、选择性以及良好的稳定性能。Ni2P/TiO2制备对催化剂的性能有影响。Ni2P负载量增加,催化剂的活性先升高后降低,Ni2P负载量为12%时催化剂活性较高。催化剂前驱体中P的质量分数越高,制备出的催化剂对苯加氢反应的稳定性越好,但随前驱体中P的质量分数增加,催化反应的活性先升高,后降低。与Ni2P/SiO2比较,Ni2P/TiO2催化剂具有较高的活性和稳定性。 相似文献
918.
Synthesis and structural studies of Co(II) and Ni(II) complexes of glutaric- and adipic dihydrazides
Glutaric dihydrazide (GDH) and adipic dihydrazide (ADH) have been found to react with Co(II) chloride and Ni(II) chloride and nitrate in ethanolic solution to form complexes of the general empirical compositionsMLCl2,ML
2Cl2 and [NiL
2(H2O)2] (NO3)2 whereM=Co(II), Ni(II) andL=GDH,ADH. Tetrahedral geometry has been proposed for 11 complexes of Co(II) and octahedral geometry for the remaining complexes based on measurements of molar conductance, magnetic susceptibility, electronic and ir spectra.
Synthese und Struktur von Co(II)- und Ni(II)-Komplexen von Glutarsäure- und Adipinsäuredihydraziden
Zusammenfassung Glutarsäuredihydrazid (GDH) und Adipinsäuredihydrazid (ADH) bilden mit Co(II)-Chlorid und Ni(II)-Chlorid bzw.-Nitrat in ethanolischer Lösung Komplexe der generellen ZusammensetzungenMLCl2,ML 2Cl2 und [NiL(H2O)2] (NO3)2, mitM=Co(II), Ni(II) undL=GDH,ADH. Für 11-Komplexe von Co(II) wird eine tetragonale Geometrie, für alle anderen Komplexe eine oktaedrische Geometrie vorgeschlagen. Die Basis dazu lieferten Messungen der molaren Leitfähigkeit, der magnetischen Suszeptibilität und der UV- bzw. IR-Spektren.相似文献
919.
Irradiations of Ni/TiO2 catalyst by UV in hydrogen at 77 K produced not only Ni+ ions on the catalyst surface, but also Ni3+ and Ti3+ species in bulk or near the interface between nickel and titania. These photo-generated species were detected and characterized by low temperature electron paramagnetic resonance (EPR) spectroscopy. Relative spin concentrations of the photogenerated paramagnetic species (Nin+ and Ti3+) varied with the nickel content in titania. A high nickel content in the sample resulted in a high peak intensity ratio of Nin+ to Ti3+. It was found that the photoinduced self-redox reaction of Ni2+ ions to form Ni+ and Ni3+ ions has a priority over the photoreduction of Ti4+ to Ti3+ ions. The characteristic EPR spectrum of the Ni3+ (3d7) ions with g1 = 2.268, g2 = 2.237, and g3 = 2.045 indicates that the Ni3+ ions are most likely located in the substitutional sites of TiO2, possibly near the surface rutile phase. The Ni+ species (3d9) with g4 = 2.130 and g1 = 2.063 are on the surface of TiO2. Both Ni+ and Ni3+ ions are quite stable in hydrogen. The Ni3+ ions seem to be responsible for anchoring the nickel ions onto titania and stablizing the Ni+ species on the surface. The Ni+ ions are thus free from oxygen poisoning and still show a high activity toward olefin oligomerization. 相似文献
920.
The First Oxoferrate(I): On the Constitution of K3[FeO2] and K3[NiO2] Garnet-red single crystals of K3[FeO2] were obtained for the first time by heating intimate mixtures of K6[CdO4] and CdO (molar ratio 1:1.16) in closed Fe-cylinders at 450°C during 40 d. The same way of preparation via “reaction with the cylinder surface” was applied to prepare similarly coloured single crystals of K3[NiO2] (K6CdO4 in closed Ni-cylinders at 500°C during 49 d). The structure determination by four circle diffractometer data (MoKα , K3[FeO2]: 731 out of 731 Io(hkl), R = 5.76%, Rw = 5.33%, K3[NiO2]: 755 out of 755 Io(hkl), R = 8.70%, Rw = 4.25%) confirms the space groups P 41212 and P 43212, respectively. K3[FeO2]: a = 604.2(2) pm, c = 1 402.7(3) pm, Z = 4 K3[NiO2]: a = 603.6(1) pm, c = 1 405.2(2) pm, Z = 4. (powder data, standard deviations in parentheses) Essential feature of the structure are the dumb-bell-like anions [O? M? O]3? (M = Fe, Ni). Their arrangement corresponds to a stuffed derivative of the KrF2-type. Magnetic properties of K3[FeO2] were determined and cover the monovalence of Fe. MAPLE-calculations reveal the strong coincidence of monovalent VIIIb-cations. 相似文献