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1.
Ozonolysis of a Series of Methylated Alkenes: Reaction Rate Coefficients and Gas‐Phase Products 下载免费PDF全文
Tristan Braure Véronique Riffault Alexandre Tomas Romeo Iulian Olariu Cecilia Arsene Yuri Bedjanian Patrice Coddeville 《国际化学动力学杂志》2015,47(9):596-605
The gas‐phase ozonolysis of three methylated alkenes, i.e., trans‐2,2‐dimethyl‐3‐hexene (22dM3H), trans‐2,5‐dimethyl‐3‐hexene (25dM3H), and 4‐methyl‐1‐pentene (4M1P), has been investigated in the presence of sufficient hydroxyl radical scavenger in a laminar flow reactor at ambient temperature (296 ± 2 K) and P = 1 atm of dry air (RH ≤ 5%). Ozone levels in the reactor were monitored by an automatic analyzer. Alkene and gas‐phase product concentrations were determined via online sampling either on three‐bed adsorbent cartridges followed by thermodesorption and GC/FID‐MS analysis or on 2,4‐dinitrophenylhydrazine (DNPH) cartridges for subsequent HPLC/UV analysis. Reaction rate coefficients of (3.38 ± 0.12) × 10?17 for 22dM3H and (2.71 ± 0.26) × 10?17 for 25dM3H, both in cm3 molecule?1 s?1 units, have been obtained under pseudo–first‐order conditions. Primary carbonyl products have been identified for the three investigated alkenes, and branching ratios are reported. In the case of 4M1P ozonolysis, the yield of a Criegee intermediate was indirectly determined. Kinetics and product study results are compared to those of literature when available. This work represents the first investigation of reaction products in the ozonolysis of 22dM3H, 25dM3H, and 4M1P in a flow reactor. 相似文献
2.
In this paper we propose time-optimal convex hull algorithms for two classes of enhanced meshes. Our first algorithm computes the convex hull of an arbitrary set ofn points in the plane inO (logn) time on a mesh with multiple broadcasting of sizen×n. The second algorithm shows that the same problem can be solved inO (1) time on a reconfigurable mesh of sizen×n. Both algorithms achieve time lower bounds for their respective model of computation.This work was supported by NASA under grant NCCI-99.Additional support by the National Science Foundation under grant CCR-8909996 is gratefully acknowledged. 相似文献
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P. Mărginean I. Mercea V. Mercea A. Olariu 《Isotopes in environmental and health studies》2013,49(4):157-160
Es wird ein Heiβ-Kalt-System mit einfachem Durchfluβ der Fluide untersucht. Dabei wird gezeigt, daβ zwischen den Isotopenkonzentrationen des Gases und der Flüssigkeit lineare Beziehungen bestehen. Eine Möglichkeit zur experimentellen Bestimmung der realen Werte der Parameter der Kolonne wird angegeben. 相似文献
6.
Mendels P Bert F de Vries MA Olariu A Harrison A Duc F Trombe JC Lord JS Amato A Baines C 《Physical review letters》2007,98(7):077204
We report muon spin rotation measurements on the S=1/2 (Cu2+) paratacamite ZnxCu4-x(OH)6Cl2 family. Despite a Weiss temperature of approximately -300 K, the x=1 compound is found to have no transition to a magnetic frozen state down to 50 mK as theoretically expected for the kagomé Heisenberg antiferromagnet. We find that the limit between a dynamical and a partly frozen ground state occurs around x=0.5. For x=1, we discuss the relevance to a singlet picture. 相似文献
7.
Pengpeng Liu Dr. Patrik Neuhaus Dr. Dmitry V. Kondratuk Prof. T. Silviu Balaban Prof. Harry L. Anderson 《Angewandte Chemie (International ed. in English)》2014,53(30):7770-7773
α‐ and β‐Cyclodextrins have been used as scaffolds for the synthesis of six‐ and seven‐legged templates by functionalizing every primary CH2OH with a 4‐pyridyl moiety. Although these templates are flexible, they are very effective for directing the synthesis of macrocyclic porphyrin oligomers consisting of six or seven porphyrin units. The transfer of chirality from the cyclodextrin templates to their nanoring hosts is evident from NMR and circular dichroism spectroscopy. Surprisingly, the mean effective molarity for binding the flexible α‐cyclodextrin‐based template within the six‐porphyrin nanoring (74 M ) is almost as high as for the previously studied rigid hexadentate template (180 M ). The discovery that flexible templates are effective in this system, and the availability of a template with a prime number of binding sites, open up many possibilities for the template‐directed synthesis of larger macrocycles. 相似文献
8.
Silviu Polosan Tahsin J. Chow Taiju Tsuboi 《Journal of Physical Organic Chemistry》2008,21(4):315-320
Electronic states and their energies are calculated for a mixed‐ligand Ir(III) compound, (5‐chloro‐8‐hydroxyquinoline) bis(2‐phenylpyridyl) iridium (called IrQ(ppy)2‐5Cl) using time‐dependent density functional theory (TDDFT) calculations and are compared with the experimental result. A good agreement is obtained between the calculated and measured absorption spectra. The d‐πQ* molecular orbital transition gives the lowest‐energy triplet state absorption band. Its energy is estimated as 1.84 eV (671 nm), which is close to the absorption band position of 1.86 eV (666 nm) observed for IrQ(ppy)2‐5Cl doped in 4,4′‐N,N′‐dicarbazole‐biphenyl (CBP) host and of 1.88 eV (660 nm) observed for IrQ(ppy)2‐5Cl doped in polystyrene (PS). The second triplet state absorption band is caused by d‐πppy transition. Its position is calculated as 2.51 eV (494 nm). The dipole moment is estimated as 3.45 D, which is lower than the dipole moment of fac‐Ir(ppy)3. This is understood by a reduced charge transfer between Ir(III) and quinoline ligand. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
9.
Reda Moubah Silviu Colis Mathieu Gallart Guy Schmerber Pierre Gilliot Aziz Dinia 《Journal of luminescence》2012,132(2):457-460
Recent studies on the physical properties of Ca3Co2O6 nanometric samples have shown that their properties are significantly different from those of the bulk samples. The origin of this change is not trivial. We have carried out optical measurements on Ca3Co2O6 thin films with different thicknesses in order to characterize their electronic structure using optical spectroscopy measurements. The absorption spectra show a dependence on the film thickness that is correlated to the grain size in the polycrystalline layers. We found that the optical band gap increases from 1.3 to 1.55 eV when the thickness changes from 35 to 100 nm. The change in the band gap evolution with the film thickness is discussed in terms of both the amorphous effect and the grain size in the Ca3Co2O6 thin films. Finally, we show that these results are consistent with recent measurements concerning magnetic and electrical properties of Ca3Co2O6 nanometric samples. 相似文献