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1.
In this paper, we investigate the evolution of joint invariants under invariant geometric flows using the theory of equivariant moving frames and the induced invariant discrete variational complex. For certain arc length preserving planar curve flows invariant under the special Euclidean group , the special linear group , and the semidirect group , we find that the induced evolution of the discrete curvature satisfies the differential‐difference mKdV, KdV, and Burgers' equations, respectively. These three equations are completely integrable, and we show that a recursion operator can be constructed by precomposing the characteristic operator of the curvature by a certain invariant difference operator. Finally, we derive the constraint for the integrability of the discrete curvature evolution to lift to the evolution of the discrete curve itself. 相似文献
2.
Dr. Benson Joseph Suman Gomosta Dr. Rini Prakash Dr. Thierry Roisnel Prof. Ashwini K. Phukan Prof. Sundargopal Ghosh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(70):16824-16832
Treatment of Li[BH3ER] (E=Se or Te, R=Ph; E=S, R=CH2Ph) with [Cp*CoCl]2 led to the formation of hydridoborate complexes, [{CoCp*Ph}{Cp*Co}{μ-EPh}{μ-κ2-E,H-EBH3}], 1a and 1 b ( 1 a : E=Se; 1 b : E=Te) and a bis-hydridoborate species [Cp*Co{μ-κ2-Se,H-SeBH3}]2, 2 . All the complexes, 1 a , 1 b and 2 are stabilized by β-agostic type interaction in which 1 b represents a novel bimetallic borate complex with a rare B−Te bond. QTAIM analysis furnished direct proof for the existence of a shared and dative B-chalcogen and Co-chalcogen interactions, respectively. In parallel to the formation of the hydridoborate complexes, the reactions also yielded tetracyclic species, [Cp*Co{κ3-E,H,H-E(BH2)2-C5Me5H3}], 3 a and 3 b ( 3 a : E=Se and 3 b : E=S), wherein the bridgehead boron atoms are surrounded by one chalcogen, one cobalt and two carbon atoms of a cyclopentane ring. Molecules 3 a and 3 b are best described as the structural mimic of tetracyclo[4.3.0.02,4.03,5]nonane having identical structure and similar valence electron counts. 相似文献
3.
Torsten Roth Vladislav Vasilenko Callum G. M. Benson Hubert Wadepohl Dominic S. Wright Lutz H. Gade 《Chemical science》2015,6(4):2506-2510
A simple, “click” synthetic approach to a new type of hybrid phosph(III)azane/NHC system is described. The presence of the phosphazane P2N2 ring unit, with P atoms flanking the NCN fragment and with this ring perpendicular to the binding site of the NHC, provides unique opportunities for modifying the electronic and steric character of these carbenes. 相似文献
4.
Rotich A. Benson Nader M. A. Mohamed Mohamed Soliman Mohammed Hassan Mohsen A. Abou Mandour 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(1):23-27
Rapid determination of gross alpha and beta emitters in urine by liquid scintillation counting is discussed. This method is based on direct addition of urine into scintillation cocktail. 241Am, 239Pu and 90Sr were selected as model radionuclides. The LSA Hidex 300 SL equipped with Triple-Double-Coincidence-Ratio technique was used for sample measurement. The work focused on optimizing the LSC cocktail to urine volume ratio with respect to the model radionuclides. The overall efficiencies for 241Am, 239Pu and 90Sr were greater than 92 %; therefore, this method would be suitable for rapid determination of gross alpha/beta activity. 相似文献
5.
6.
David John Benson 《Archiv der Mathematik》2017,109(5):413-414
Let K be a field of characteristic zero, and let R be a ring containing K. Then either \(R^\times = K^\times \) or \(K^\times \) is a subgroup of infinite index in \(R^\times \). 相似文献
7.
Jordan De Jesus Silva Niccolò Bartalucci Benson Jelier Samantha Grosslight Tobias Gensch Claas Schünemann Bernd Müller Paul C. J. Kamer Christophe Copéret Matthew S. Sigman Antonio Togni 《Helvetica chimica acta》2021,104(12):e2100200
A synthetic method for the palladium-catalyzed cyanation of aryl boronic acids using bench stable and non-toxic N-cyanosuccinimide has been developed. High-throughput experimentation facilitated the screen of 90 different ligands and the resultant statistical data analysis identified that ligand σ-donation, π-acidity and sterics are key drivers that govern yield. Categorization into three ligand groups – monophosphines, bisphosphines and miscellaneous – was performed before the analysis. For the monophosphines, the yield of the reaction increases for strong σ-donating, weak π-accepting ligands, with flexible pendant substituents. For the bisphosphines, the yield predominantly correlates with ligand lability. The applicability of the designed reaction to a wider substrate scope was investigated, showing good functional group tolerance in particular with boronic acids bearing electron-withdrawing substituents. This work outlines the development of a novel reaction, coupled with a fast and efficient workflow to gain understanding of the optimal ligand properties for the design of improved palladium cross-coupling catalysts. 相似文献
8.
A phenomenological high strain rate model with failure for ice 总被引:3,自引:0,他引:3
Kelly S. Carney David J. Benson Paul DuBois Ryan Lee 《International Journal of Solids and Structures》2006,43(25-26):7820-7839
9.
10.
Koushik Saha Benson Joseph Rongala Ramalakshmi Dr. R. S. Anju Dr. Babu Varghese Prof. Sundargopal Ghosh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(23):7871-7878
Thermolysis of [Cp*Ru(PPh2(CH2)PPh2)BH2(L2)] 1 (Cp*=η5‐C5Me5; L=C7H4NS2), with terminal alkynes led to the formation of η4‐σ,π‐borataallyl complexes [Cp*Ru(μ‐H)B{R‐C=CH2}(L)2] ( 2 a – c ) and η2‐vinylborane complexes [Cp*Ru(R‐C=CH2)BH(L)2] ( 3 a – c ) ( 2 a , 3 a : R=Ph; 2 b , 3 b : R=COOCH3; 2 c , 3 c : R=p‐CH3‐C6H4; L=C7H4NS2) through hydroboration reaction. Ruthenium and the HBCC unit of the vinylborane moiety in 2 a – c are linked by a unique η4‐interaction. Conversions of 1 into 3 a – c proceed through the formation of intermediates 2 a – c . Furthermore, in an attempt to expand the library of these novel complexes, chemistry of σ‐borane complex [Cp*RuCO(μ‐H)BH2L] 4 (L=C7H4NS2) was investigated with both internal and terminal alkynes. Interestingly, under photolytic conditions, 4 reacts with methyl propiolate to generate the η4‐σ,π‐borataallyl complexes [Cp*Ru(μ‐H)BH{R‐C=CH2}(L)] 5 and [Cp*Ru(μ‐H)BH{HC=CH‐R}(L)] 6 (R=COOCH3; L=C7H4NS2) by Markovnikov and anti‐Markovnikov hydroboration. In an extension, photolysis of 4 in the presence of dimethyl acetylenedicarboxylate yielded η4‐σ,π‐borataallyl complex [Cp*Ru(μ‐H)BH{R‐C=CH‐R}(L)] 7 (R=COOCH3; L=C7H4NS2). An agostic interaction was also found to be present in 2 a – c and 5 – 7 , which is rare among the borataallyl complexes. All the new compounds have been characterized in solution by IR, 1H, 11B, 13C NMR spectroscopy, mass spectrometry and the structural types were unequivocally established by crystallographic analysis of 2 b , 3 a – c and 5 – 7 . DFT calculations were performed to evaluate possible bonding and electronic structures of the new compounds. 相似文献