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排序方式: 共有185条查询结果,搜索用时 265 毫秒
1.
Most successful heuristics for solving 1||∑wjTj are based on swap moves. We present an algorithm which improves the complexity of searching the swap neighborhood from O(n3) to O(n2). We show that this result also improves the complexity of the recently developed dynasearch heuristics. 相似文献
2.
The aim of this paper is to study the laser-induced backside wet cleaning techniques for glass substrates. Two kinds of laser cleaning techniques are proposed in this study. The first involves applying an Nd:YAG laser to the backside of the substrate which is submerged in water. A metal plate is placed below the glass substrate. Most of the laser energy will be absorbed by the metal plate. The metal then vaporizes the water and generates a turbulent bubble flow. The bubble flow removes the alumina particles from the surface of the glass substrate. The second involves using a CO2 laser to generate turbulent bubble flow to remove the particles. Both methods were successfully demonstrated for the removal of submicron particles of 0.5 μm in size. The phenomena of bubble generation and diffusion are presented in the paper. Because the laser is applied to the backside of the substrate, the damage due to the laser heat can be significantly reduced. The quality and efficient of the backside processing is better than those of the front side processing. The proposed techniques have great potential to provide an improved solution for glass cleaning. 相似文献
3.
The article describes the synthesis and extraction properties of a new chiral calix[4]arene Schiff base ligand 5, which has been synthesized from 5,17-diformyl-25,27-bis-(4-nitrobenzyloxy)-26,28-dihidroxycalix[4]arene (4) by treatment with (S)-(-)-1-phenylethylamine. In this synthesis, it was thought to explore the role of chiral, as well as Schiff base sites in the recognition of targeted species ions (such as dichromate anions) as well as neutral/chiral molecules. At low pH, the ligand 5 is more effective for transferring the dichromate anions from an aqueous into a dichloromethane layer; may be due to the protonation of nitrogen atoms. The extraction properties of ligand 5 towards the some selected α -amino acid methylesters are also reported. However, the ligand 5 did not display any selectivity towards the selected α-amino acid methylesters. 相似文献
4.
We report herein the synthesis of a novel class of compounds, ethyl 4-oxo-4H-furo[3,2-c]pyran-6-yl carbonate, (7E)-7-[(dimethylamino)methylene]-4H-furo[3,2-c]pyran-4,6(7H)-dione, 5-oxo-N-phenyl-2,5-dihydro-4H-furo[3,2-b]pyrrole-4-carboxamide, and 5-oxo-N-phenyl-5,6-dihydro-4H-thieno[3,2-b]pyrrole-4-carboxamide starting from the corresponding acid derivatives. Intramolecular cyclization in the presence of thionyl chloride formed the target fused ring systems. Additional transformation was seen in the cyclization of furan-fused heterocycle. A mechanism was proposed based on experimental and computational findings. 相似文献
5.
The B,N-bifunctional catalyst homoboroproline has been applied to a catalytic asymmetric nitroalkene-Michael addition to β-nitrostyrene analogues, showing broad substrate tolerance, high conversions and moderate to good asymmetric induction. The ability of homoboroproline to act as an efficient catalyst based on enamine-formation of the secondary amine, coupled with intramolecular Lewis-acid chelation of the nitro function, in a non-FLP manner, to effect efficient and enantioselective catalysis via a proposed large 10-membered ring transition state is remarkable and reinforced by theoretical calculations. 相似文献
6.
At present, CNT supported catalysts were prepared by two different methods as NaBH4 reduction and dendrimer templated NaBH4 reduction method to observe the effect of preparation method on the sensitivity and activity of H2O2 reduction. Then, CNT supported PdxAuy bimetallic nanocatalysts having various atomic ratio were synthesized via novel dendrimer templated NaBH4 reduction method. The resulting materials were characterized employing XRD and TEM. Crystallite size of 10 %Pd0.7Au0.3/CNTdendrimer was obtained from XRD 17.1 nm and mean particle size obtained from TEM is about 15 nm. Moreover, the electrochemical behavior of these catalysts was characterized by cyclic voltammetry (CV) and chronoamperometry (CA) techniques. PdxAuy bimetallic nanocatalysts have excellent electrocatalytic properties and great potential for applications in electrochemical detection. The sensitivity and the limit of detection values for the prepared sensor with monometallic 10 % Pd/CNTdendrimer catalysts are 219.78 μA mM?1cm?2 and 2.6 μM, respectively. However, the sensor constructed with 10 %Pd0.7Au0.3/CNTdendrimer modified electrode has a very high sensitivity of 316.89 μA mM?1 cm?2 with a quick response time of 2 s and a wide linear range of 0.001–19.0 mM. In addition, the interference experiment indicated that the 10 % Pd0.7Au0.3/CNTdendrimer nanoparticles have good selectivity toward H2O2. 相似文献
7.
Gavrishchaka VV Ganguli GI Scales WA Slinker SP Chaston CC McFadden JP Ergun RE Carlson CW 《Physical review letters》2000,85(20):4285-4288
Linear theory analysis and particle-in-cell simulations show that a spatial transverse gradient in the ion drift parallel to the magnetic field, dV(di)/dx=Omega(i), where Omega(i) is the ion cyclotron frequency, can generate a broadband multimode spectrum extending from omegaOmega(i). Nonlinearly, these waves lead to multiscale spatially coherent structures, substantial cross-field transport, ion energization, and phase-space diffusion. Large spikes are formed in the parallel electric field time series. These signatures are similar to the Fast Auroral Snapshot satellite observations in the upward current region. 相似文献
8.
Ozlem Karahan Duygu Avci Vİktorya Avİyente 《Journal of polymer science. Part A, Polymer chemistry》2011,49(14):3058-3068
A series of alkyl α‐hydroxymethacrylate derivatives with various secondary functionalities (ether, ester, carbonate, and carbamate) and terminal groups (alkyl, cyano, oxetane, cyclic carbonate, phenyl and morpholine) were synthesized to investigate the effect of intermolecular interactions, H‐bonding, π–π interactions, and dipole moment on monomer reactivity. All of the monomers except one ester and one ether derivative are novel. The polymerization rates, determined by using photo‐DSC, showed the average trend (aromatic carbamate > hydroxyl > ester > carbonate ~ aliphatic carbamate ~ ether), with several exceptions due to the differences in terminal groups. There is a correlation between the chemical shift differences of the double bond carbons, the calculated dipole moments, and the reactivities only for nonhydrogen bonded monomers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
9.
Ozlem Yazici M. Reyhan Moroglu Husnu Cankurtaran Ozlem Cankurtaran Ferdane Karaman 《Mikrochimica acta》2008,160(4):441-445
The composites of graphite with Ardel?D-100 which is a trademark of a polyester of bisphenol-A with terephthalic and isophthalic acid were used as a sensing material
in a conductometric vapor sensor. The magnitudes of responses are increased in the order of benzene, isobutyl acetate, isoamyl
acetate, ethyl benzene and chloro benzene. This suggests that Ardel?D-100 can be used as a sensing material for chlorobenzene, ethyl benzene and isoamyl acetate. On the other hand, specific
retention volumes of the sensed vapors on Ardel?D-100 coated on graphite were determined by inverse gas chromatography at temperatures between 200 and 260 °C. The distribution
coefficient, K
s of the vapors between stationary and mobile phases in the column was obtained. It was revealed for the first time that the
logarithm of K
s of the solvents varies almost linearly with their responses based on conductometric resistance of the sensing polymer composite.
Subsequently, the study suggests that gas chromatographic retention data can be used in prediction of the conductometric responses
of a polymeric sensor to vapors.
Correspondence: Ferdane Karaman, Department of Chemistry, Yildiz Technical University, 34220 Istanbul-Esenler, Turkey 相似文献
10.
Two non-linear azide containing heteronuclear complexes: crystal structure and thermal decomposition
S. Öz R. Kurtaran C. Arıcı Ü. Ergun F. N. Dinçer Kaya K. C. Emregül O. Atakol D. Ülkü 《Journal of Thermal Analysis and Calorimetry》2010,99(1):363-368
Bis-N,N′(salicylidene)-2,2′-dimethyl-1,3-propanediamine (LDMH2) has a high tendency to form polynuclear complexes. Two trinuclear complexes were obtained using this ligand and azide ions;
(CuLDM)2 · Mn(N3)2 · (DMF)2, [(C19H20N2O2Cu)2 · Mn(N3)2 · (C3H7NO)2] and (CuLDM)2 · Cd(N3)2 · (DMF)2, [(C19H20N2O2Cu)2 · Cd(N3)2 · (C3H7NO)2]. The structures were identified with X-ray methods. TG and DSC methods were also employed to these complexes. Studies showed
the (CuLDM)2 · Mn(N3)2 · (DMF)2 and (CuLDM)2 · Cd(N3)2 · (DMF)2 to be non-linear. Also μ-bridges were not encountered for the azide ions but were seen to form between the Cu and other metal
via phenolic oxygens. Thermal analysis showed exothermic degradation of the azide ions destroying the trinuclear structure.
Although azide containing structures show explosive characteristics, this was not observed for the present compounds. 相似文献