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71.
John R. Tate Katherine Kantardjieff Guy Crundwell Larry M. Mink 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(9):m485-m486
In the title compound, [PtBr2(C48H36N4O4)]·0.896CHCl3·0.569CH3CN, the centrosymmetric metal complex is octahedral, with the porphyrin ring essentially planar and the Br atoms occupying axial positions. The two independent methoxyphenyl substituents are tilted at angles of 89.0 and 67.0° with respect to the porphyrin plane. The Pt—N distances are 2.035 (4) and 2.036 (4) Å and the Pt—Br distance is 2.4666 (6) Å. Chloroform and acetonitrile solvent molecules, exhibiting substantial disorder, occupy positions between the porphyrin molecules. This is the first crystal and molecular structure of a PtIV–porphyrin complex to be reported. 相似文献
72.
Newer reversed-phase column technologies that incorporate polar groups either by an endcapping procedure or by embedding them into the stationary phase ligand have been receiving much attention in the literature for their robustness when highly aqueous conditions are used. We investigated their ability to accurately determine the chromatographic hydrophobicity value log k'w. The non-linear deviations of retention data as mobile phase conditions approach zero percent modifier are a large source of error when extrapolating to log k'w values using the linear solvent strength model. Here, we compare a conventional reversed-phase stationary phase with others that have incorporated either polar embedded or polar endcapped phases, along with a hybrid-based particle derivatized with a polar embedded ligand. Our results show that polar endcapped phases perform very similarly to the conventional phase and do not show any improved ability for determining log k'w, but polar embedded phases have reduced curvature in the data, and therefore result in less error in extrapolation. We also investigated the solubility parameter model and the [ET(30)] model for their extrapolation efficiency, and have concluded that the [ET(30)] model shows the least error when extrapolating the data. 相似文献
73.
Ueno Y Tate A Niwa O Zhou HS Yamada T Honma I 《Analytical and bioanalytical chemistry》2005,382(3):804-809
The gas selectivities of highly ordered mesoporous silicates and commercially-obtained porous silicates with respect to benzene, toluene and xylene were studied. After studying the porosities, pore uniformities, and surface silanol structures of the silicates and their relationships to gas selectivity in detail, we found that we could achieve high benzene selectivity by controlling the micropore size (less than 1 nm). Concluding that mesoporous silicate has a suitable micropore size and structure for benzene selectivity, we also observed that mesoporous silicate SBA-16 exhibited a high (>6) benzene selectivity from toluene and xylene even in a pseudo-atmospheric environment. A benzene detection limit of about 100 ppb was achieved by introducing SBA-16 into a microfluidic device originally developed for the separate detection of benzene, toluene, and xylene gases. 相似文献
74.
T. A. Antkowiak A. E. Oberster A. F. Halasa D. P. Tate 《Journal of polymer science. Part A, Polymer chemistry》1972,10(5):1319-1334
Addition of polar modifiers to alkyllithium-initiated homopolymerizations of butadiene causes substantial changes in the microstructure of the polymers produced. These changes are shown to depend not only on the concentration of modifier, but also on the polymerization temperature. The combined effects of modifier concentration and reaction temperature have been considered, and a method is presented for quickly determining the proper conditions for preparation of a polybutadiene of any 1,2-microstructure within a range of 10–80%. It is also shown that in anionic polar-modified copolymerizations of butadiene–styrene, the reaction temperature is again critical. Within a certain concentration range of modifier, the temperature will influence the rate of styrene incorporation or the randomness of styrene units in the resulting copolymers. 相似文献
75.
Busch GK Tate EW Gaffney PR Rosivatz E Woscholski R Leatherbarrow RJ 《Chemical communications (Cambridge, England)》2008,(29):3369-3371
We report an effective strategy for generating N-terminal cysteinyl proteins by proteolytic cleavage using the enzyme 3C pro, suitable for a wide range of applications via native chemical ligation. 相似文献
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Dr. Gregory B. Craven Dr. Dominic P. Affron Dr. Charlotte E. Allen Dr. Stefan Matthies Dr. Joe G. Greener Dr. Rhodri M. L. Morgan Prof. Edward W. Tate Prof. Alan Armstrong Dr. David J. Mann 《Angewandte Chemie (International ed. in English)》2018,57(19):5257-5261
Cysteine‐reactive small molecules are used as chemical probes of biological systems and as medicines. Identifying high‐quality covalent ligands requires comprehensive kinetic analysis to distinguish selective binders from pan‐reactive compounds. Quantitative irreversible tethering (qIT), a general method for screening cysteine‐reactive small molecules based upon the maximization of kinetic selectivity, is described. This method was applied prospectively to discover covalent fragments that target the clinically important cell cycle regulator Cdk2. Crystal structures of the inhibitor complexes validate the approach and guide further optimization. The power of this technique is highlighted by the identification of a Cdk2‐selective allosteric (type IV) kinase inhibitor whose novel mode‐of‐action could be exploited therapeutically. 相似文献
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