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171.
We have developed a selective low-temperature synthesis of fac and mer tris-cyclometalated Ir(III) complexes. The chloro-bridged dimers [Ir(CwedgeN)2Cl]2 (CwedgeN = cyclometalating ligand) are cleaved in coordinating solvents like acetonitrile to give neutral Ir(CwedgeN)2(NCCH3)Cl species which in turn are reacted with AgPF6 to give hexafluorophosphate salts of the bis-acetonitrile species [Ir(CwedgeN)2(NCCH3)2]PF6 for CwedgeN = 2,2'-thienylpyridine (thpy) and 2-phenylpyridine (ppy). These bis-acetonitrile complexes are excellent starting materials for the synthesis of tris-Ir(III) complexes. The complexes of the general formula fac-Ir(CwedgeN)3 were synthesized with the ligands thpy and ppy at 100 degrees C in o-dichlorobenzene from the corresponding [Ir(CwedgeN)2(NCCH3)2]PF6 complexes. The reaction of [Ir(CwedgeN)2(NCCH3)2]PF6 with thpy at room temperature did not give the expected tris complex but instead gave [Ir(thpy)2(N,S-thpy)]PF6, with the third chelating ligand complexed through the sulfur atom of the thiophene ring. [Ir(thpy)2Cl]2, [Ir(ppy)2Cl]2, Ir(thpy)2(NCCH3)Cl, [Ir(thpy)2(NCCH3)2]PF6, [Ir(ppy)2(NCCH3)2]PF6, and [Ir(thpy)2(N,S-thpy)]PF6 were structurally characterized by X-ray crystallography. Additionally, hydroxy-bridged dimers, [Ir(CwedgeN)2(OH)]2, were synthesized as starting materials for the selective synthesis of mer-Ir(CwedgeN)3 complexes at 100 degrees C in o-dichlorobenzene. A mechanism is proposed that may account for the selectivity observed in the formation of the mer-Ir(CwedgeN)3 and fac-Ir(CwedgeN)3 isomers in previous studies and the studies presented here. 相似文献
172.
Jalkanen JP Halonen M Fernández-Torre D Laasonen K Halonen L 《The journal of physical chemistry. A》2007,111(49):12317-12326
The adsorption of silver and gold atoms, and M2, M6, and M13 (M=Ag or Au) clusters on the (0001) graphite surface has been investigated computationally using the density functional theory (DFT) with periodic boundary conditions and plane wave basis functions. The surface has been modeled as a single carbon sheet. The role of dispersion forces has been studied with an empirical classical model. The results show that the clusters avoid hollow sites on the graphite surface, and that the metal atoms favor atop and bond sites. Large structural changes are observed in octahedral M6 and icosahedral M13 clusters on the graphite surface when compared with gas-phase geometries. The results also indicate that if accurate results are required, the dispersion forces between metal and carbon atoms should be included in the studied systems. 相似文献
173.
Adipic and malonic acid aqueous solutions: surface tensions and saturation vapor pressures 总被引:1,自引:0,他引:1
Riipinen I Koponen IK Frank GP Hyvärinen AP Vanhanen J Lihavainen H Lehtinen KE Bilde M Kulmala M 《The journal of physical chemistry. A》2007,111(50):12995-13002
The surface tension of adipic aqueous solutions was measured as a function of temperature (T=278-313 K) and adipic acid mole fraction (X=0.000-0.003) using the Wilhelmy plate method. A parametrization fitted to these data is presented. The evaporation rates of binary water-malonic and water-adipic acid droplets were measured with a TDMA technique at different temperatures (T=293-300 K) and relative humidities (58-80%), and the saturation vapor pressures of subcooled liquid malonic and adipic acids were derived from the data using a binary evaporation model. The temperature dependence of the vapor pressures was obtained as least-squares fits to the derived vapor pressures: ln(Psat,l) (Pa)=220.2389-22634.96/T (K)-26.66767 ln T (K) for malonic acid and ln(Psat,l) (Pa)=140.6704-18230.97/T (K)-15.48011 ln T (K) for adipic acid. 相似文献
174.
The first synthetic route to amaminol A with use of an organocatalytic intramolecular Diels-Alder reaction is reported. The absolute stereochemistry is proven with a crystallographic image of a cyclic carbamate of amaminol A. 相似文献
175.
Inside Cover: Efficient Self‐Assembly of Di‐, Tri‐, Tetra‐, and Hexavalent Hosts with Predefined Geometries for the Investigation of Multivalency (Chem. Eur. J. 37/2015)
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176.
Natalia Tong-Ochoa Kari Kopra Markku Syrjänpää Nicolas Legrand Harri Härmä 《Analytica chimica acta》2015
Protein post-translational modifications (PTMs) are regulatory mechanisms carried out by different enzymes in a cell. Kinase catalyzed phosphorylation is one of the most important PTM affecting the protein activity and function. We have developed a single-label quenching resonance energy transfer (QRET) assay to monitor tyrosine phosphorylation in a homogeneous high throughput compatible format. Epidermal growth factor receptor (EGFR) induced phosphorylation was monitored using Eu3+-chelate labeled peptide and label-free phosphotyrosine specific antibody in presence of a soluble quencher molecule. In the QRET kinase assay, antibody binding to phosphorylated Eu3+-peptide protects the Eu3+-chelate from luminescence quenching, monitoring high time-resolved luminescence (TRL) signals. In the presence of specific kinase inhibitor, antibody recognition and Eu3+-chelate protection is prevented, allowing an efficient luminescence quenching. The assay functionality was demonstrated with a panel of EGFR inhibitors (AG-1478, compound 56, erlotinib, PD174265, and staurosporine). The monitored IC50 values ranged from 0.08 to 155.3 nM and were comparable to those found in the literature. EGFR activity and inhibition assays were performed using low nanomolar enzyme and antibody concentration in a 384-well plate format, demonstrating its compatibility for high throughput screening (HTS). 相似文献
177.
178.
Water Structure Recovery in Chaotropic Anion Recognition: High‐Affinity Binding of Dodecaborate Clusters to γ‐Cyclodextrin
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Khaleel I. Assaf Merve S. Ural Dr. Fangfang Pan Tony Georgiev Prof. Svetlana Simova Prof. Kari Rissanen Prof. Detlef Gabel Prof. Werner M. Nau 《Angewandte Chemie (International ed. in English)》2015,54(23):6852-6856
Dodecaborate anions of the type B12X122? and B12X11Y2? (X=H, Cl, Br, I and Y=OH, SH, NH3+, NR3+) form strong (Ka up to 106 L mol?1, for B12Br122?) inclusion complexes with γ‐cyclodextrin (γ‐CD). The micromolar affinities reached are the highest known for this native CD. The complexation exhibits highly negative enthalpies (up to ?25 kcal mol?1) and entropies (TΔS up to ?18.4 kcal mol?1, both for B12I122?), which position these guests at the bottom end of the well‐known enthalpy‐entropy correlation for CDs. The high driving force can be traced back to a chaotropic effect, according to which chaotropic anions have an intrinsic affinity to hydrophobic cavities in aqueous solution. In line with this argument, salting‐in effects revealed dodecaborates as superchaotropic dianions. 相似文献
179.
Superchiral Pd3L6 Coordination Complex and Its Reversible Structural Conversion into Pd3L3Cl6 Metallocycles
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Dr. Ondřej Jurček Pia Bonakdarzadeh Dr. Elina Kalenius Dr. Juha Matti Linnanto Dr. Michael Groessl Dr. Richard Knochenmuss Prof. Janne A. Ihalainen Prof. Kari Rissanen 《Angewandte Chemie (International ed. in English)》2015,54(51):15462-15467
Large, non‐symmetrical, inherently chiral bispyridyl ligand L derived from natural ursodeoxycholic bile acid was used for square–planar coordination of tetravalent PdII, yielding the cationic single enantiomer of superchiral coordination complex 1 Pd3 L 6 containing 60 well‐defined chiral centers in its flower‐like structure. Complex 1 can readily be transformed by addition of chloride into a smaller enantiomerically pure cyclic trimer 2 Pd3 L 3Cl6 containing 30 chiral centers. This transformation is reversible and can be restored by the addition of silver cations. Furthermore, a mixture of two constitutional isomers of trimer, 2 and 2′ , and dimer, 3 and 3′ , can be obtained directly from L by its coordination to trans‐ or cis‐N‐pyridyl‐coordinating PdII. These intriguing, water‐resistant, stable supramolecular assemblies have been thoroughly described by 1H DOSY NMR, mass spectrometry, circular dichroism, molecular modelling, and drift tube ion‐mobility mass spectrometry. 相似文献
180.
Joakim M. Johansen Martti Aho Kari Paakkinen Raili Taipale Helge Egsgaard Jon G. Jakobsen Flemming J. Frandsen Peter Glarborg 《Proceedings of the Combustion Institute》2013,34(2):2363-2372
Studies of the release of critical ash-forming elements from combustion of biomass are typically conducted with small sample masses under well controlled conditions. In biomass combustion on a grate, secondary recapture and release reactions in the fuel-bed may affect the overall release and partitioning of these elements. Earlier work by the authors on the release of K, Cl, and S from a high-chlorine biomass (corn stover) in a lab-scale setup is, in the present work, supplemented with novel results from a bench-scale fixed bed reactor and a 100 kW moving grate pilot facility. The results from the bench-scale reactor indicate that S and K release are not significantly affected by secondary reactions, while Cl is partly recaptured by secondary reactions in the char. A linear increase in K-release was observed from 50% at 906 °C to almost 80 wt.% at 1234 °C when firing only corn stover. A similar release profile was observed for Cl, from 65% to nearly 100%. Complete release of S was achieved at 1234 °C with a linear increase from 70% at 906 °C. Co-combustion of corn stover with low-Cl wood chips served to increase the bed temperature, resulting in complete and close to complete release of Cl and S, respectively. An increase in the relative K-release was observed when increasing the wood chip fraction from 40% to 100% (energy basis). Pilot scale flue gas results indicate that the share of Cl released as HCl decreases towards 0% as the share of wood chips is increased towards 100%. Hence, co-combustion of corn stover with wood chips is expected to decrease the absolute release of KCl due to the lower feedstock quantity of Cl, however, increase the relative release of Cl as KCl. 相似文献