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101.
102.
Summary The gases evolved from geothermal fields, after condensation of H2O, CO2, H2S and NH3 in caustic solution, contain He, H2, Ar, O2, N2, CH4 and higher hydrocarbons. The analysis for the major components in these residual gas mixtures can be achieved by use of two simple gas chromatographs in parallel, and using 5Å molecular sieve. The separation of He and H2 to baseline is achieved by using low temperatures (30°C) coupled with a relatively long column; and the difficult separation of Ar and O2 is achieved by use of a cryogenically cooled column. The use of switching valves to backflush and bypass columns ensures that a minimum time for analysis can be achieved whilst retaining baseline separations of the He/H2 and Ar/O2 pairs. 相似文献
103.
介孔分子筛上的蛋白质直接电化学 总被引:2,自引:0,他引:2
将介孔分子筛用于不同含血红素蛋白质的直接电子传递研究,分别研究了辣根过氧化物酶、血红蛋白和肌红蛋白在六方介孔硅(HMS)上的直接电化学,探讨了介孔分子筛与这些蛋白质间的相互作用,构建了过氧化氢和亚硝酸根的新型的生物传感器. 这些工作扩展了HMS在蛋白质固定、直接电子传递研究和无试剂生物传感器制备方面的应用. 相似文献
104.
M.A. Zanjanchi Sh. Sohrabnejad 《Journal of inclusion phenomena and macrocyclic chemistry》2003,46(1-2):43-49
The intercalation of methylene blue into mordenite zeolite was studied by diffuse reflectance spectroscopy. Methylene blue was incorporated into mordenite by ion exchange in the aqueous phase. Samples of sodium, calcium and protonated mordenite were subjected to methylene blue loading. The DR spectra observed shortly after mixing the dye with sodium mordenite are those of aggregated species adsorbed on the surface. The period of intercalation is very short (1 h) for protonated mordenite and is too long for calcium mordenite (7 days). The hydrated mordenite samples containing intercalated methylene blue show two 660 and 610 nm bands which are assigned to monomeric and dimeric species of methylene blue, respectively. Upon dehydration a new band at 745 nm is observed which corresponds to the protonated dye molecule. The intensity of this band increases with severity of dehydration. Those dehydrated samples containing merely aggregated dye molecules adsorbed on the surface do not show the 745 nm band. The protonation of methylene blue is reversible by the dehydration-hydration process. 相似文献
105.
106.
Jacek Michalik Marek Danilczuk Janusz Turek Jaroslaw Sadlo 《Research on Chemical Intermediates》2007,33(8):793-806
This paper presents studies on paramagnetic intermediates, free atoms and radicals produced in γ-irradiated molecular sieves and their reactions with adsorbate molecules or exchangeable cations. Four different systems
have been investigated using EPR spectroscopy, Na-A/CH4, AgNa-A/CH3OH, Ag-SAPO-11/C2H4 and AgCs-rho/NH3. It was found that methyl radicals are formed in two different sites in Na-A/CH4 and in one of them they are stable at room temperature. The formation of Ag·CH2OH+ radical cation with one-electron bond between silver and carbon has been established in AgNa-A/CH3OH by EPR experiments with [13C]CH3OH and DFT calculations. In Ag-SAPO-11/C2H4 the stabilisation of biligand silver/ethylene complex, Ag0(C2H4)2 was postulated based on EPR and DFT results. Tetrameric silver clusters (Ag
4
3+
) produced radiolytically in AgCs-rho/NH3 strongly interact with two ammonia molecules as was deduced from the changes in superhyperfine structure of high-field EPR
line of Ag
4
3+
pentet for zeolite exposed to [14N]NH3 and [15N]NH3. The presented examples clearly show that the combination of radiation methods with EPR technique is very useful to study
the structure and reactivity of paramagnetic intermediates. 相似文献
107.
Mohamed Elanany Bao-Lian Su Daniel P. Vercauteren 《Journal of molecular catalysis. A, Chemical》2007,270(1-2):295-301
The hydrothermal genesis of AlPO4-5, in the presence of four different organic templates, viz., methyldicyclohexylamine (MCHA), triethylamine (TEA), tripropylamine (TPA), and tetraethylammonium hydroxide (TEAOH), has been monitored by XRD. It is shown that TEAOH has the best templating ability to the formation of AlPO4-5 structure under the different synthesis conditions considered in this study. Density functional calculations on periodic models of AlPO4-5 indicate the strongest nonbonding interaction energy between the template and the framework in the case of TEAOH. Therefore, a new approach correlating the nonbonding interaction energy to the template ability to form a porous structure is proposed as a step toward a better understanding of the role of the organic template in the synthesis of porous molecular sieves. 相似文献
108.
109.
The Difference Between Consecutive Primes, II 总被引:6,自引:0,他引:6
The authors sharpen a result of Baker and Harman (1995), showingthat [x, x + x0.525] contains prime numbers for large x. Animportant step in the proof is the application of a theoremof Watt (1995) on a mean value containing the fourth power ofthe zeta function. 2000 Mathematical Subject Classification:11N05. 相似文献
110.
A scheme to obtain approximate analytical functions for the atomic distributed multipole moments of the crystallographically different atoms within aluminosilicate and aluminophosphate sieves is discussed. Respective atomic multipole moments are derived within the CRYSTAL95 ab initio periodic Hartree–Fock code with different basis sets, from minimal STO‐3G to 6‐21G*. In order to illustrate the possible applications, distributed analyses are carried out for various structural models from all‐siliceous zeolites and aluminophosphates with ratio Al/P=1 to hydrogen forms of aluminosilicates. Simple approximate forms based on charge and geometry coordinates are proposed for the high‐order moments of each atom, which are further required for the calculation of the electrostatic field within the structures. The possibility to use this analytical approach to evaluate the electrostatic field within embedded cluster models is also shortly discussed. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 83: 70–85, 2001 相似文献