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排序方式: 共有903条查询结果,搜索用时 31 毫秒
101.
T. Kozik J. Buschmann K. Grotowski H. J. Gils N. Heide J. Kiener H. Klewe-Nebenius H. Rebel S. Zagromski A. J. Cole S. Micek 《Zeitschrift für Physik A Hadrons and Nuclei》1987,326(4):421-428
Intermediate mass fragment cross-sectionsσ(E, θ, 4≤Z≤11) have been measured in the reaction6Li+46Ti at 156 MeV incident energy. A simple sequential binary decay model describes most of theZ>8 data as evaporation from the compound nucleus. The complete fusion cross-section is also well reproduced. An intermediate velocity source model (β=2β CN, T=7 MeV) has been used in order to explain the small angle and Z≤8 data which indicate aZ ?4.1 dependence. 相似文献
102.
Yang Cai Zhenzhen Mo Nalaka S. Rannulu Bing Guan Srinivasan Kannupal Bruce C. Gibb Richard B. Cole 《Journal of mass spectrometry : JMS》2010,45(3):235-240
Electrospray‐generated precursor ions usually follow the ‘even‐electron rule’ and yield ‘closed shell’ fragment ions. We characterize an exception to the ‘even‐electron rule.’ In negative ion electrospray mass spectrometry (ES‐MS), 2‐(ethoxymethoxy)‐3‐hydroxyphenol (2‐hydroxyl protected pyrogallol) easily formed a deprotonated molecular ion (M‐H)? at m/z 183. Upon low‐energy collision induced decomposition (CID), the m/z 183 precursor yielded a radical ion at m/z 124 as the base peak. The radical anion at m/z 124 was still the major fragment at all tested collision energies between 0 and 50 eV (Elab). Supported by computational studies, the appearance of the radical anion at m/z 124 as the major product ion can be attributed to the combination of a low reverse activation barrier and resonance stabilization of the product ions. Furthermore, our data lead to the proposal of a novel alternative radical formation pathway in the protection group removal of pyrogallol. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
103.
Lan-Ying Qin Andrew G. Cole Marc-Raleigh Brescia Joan J. Zhang James R. Wareing Juerg Zimmermann John J. Baldwin 《Tetrahedron letters》2010,51(34):4486-4489
A facile synthesis of novel 2-amino-6-arylmethyl-7-carboxamido-7,8-dihydropyrimido[5,4-f][1,4]thiazepin-5-ones is described. The synthesis was developed on solid phase and was applied to provide a series of analogs in good yield. The key reactions are acylation of a cysteine derivative with 2,4-dichloropyrimidine-5-carbonyl chloride followed by cyclization to generate a 6-arylmethyl-7-carboxamido-2-chloro-7,8-dihydropyrimido[5,4-f][1,4]thiazepin-5-one, which is further derivatized with an amine to give the desired 2-amino-6-arylmethyl-7-carboxamido-7,8-dihydropyrimido[5,4-f][1,4]thiazepin-5-one. 相似文献
104.
Megan A. Cole Christopher N. Bowman 《Journal of polymer science. Part A, Polymer chemistry》2013,51(8):1749-1757
Polysiloxanes are commonly used in a myriad of applications, and the “click” nature of the thiol‐ene reaction is well suited for introducing alternative functionalities or for crosslinking these ubiquitous polymers. As such, understanding of the thiol‐ene reaction in the presence of silicones is valuable and would lead to enhanced methodologies for modification and crosslinking. Here, the thiol‐ene reaction kinetics were investigated in functionalized oligosiloxanes having varying degrees of thiol functionalization (SH), π–π interactions (from diphenyls, DP), and ene types (C?C). In the ene‐functionalized oligomers, π–π interactions were controlled through the use of dioctyl repeats (DO). The polymerization rate and rate‐limiting steps were determined for all systems containing an allyl‐functionalized oligomer, and rates ranging from 0.10 to 0.54 mol L?1 min?1 were seen. The rate‐limiting step varied with the oligomer composition; examples of rate‐limited propagation (5:3:2 C?C:DP:DO/1:1 SH:DP) or chain transfer (5:3:2 C?C:DP:DO/3:1 SH:DP) were found in addition to cases with similar reaction rate constants (5:2:3 C?C:DP:DO/1:1 SH:DP). None of the siloxanes were found to exhibit autoacceleration despite their relatively high viscosities. Instead, the allyl‐, vinyl‐, and acrylate‐functionalized siloxanes were all found to undergo unimolecular termination based on their high α scaling values (0.98, 0.95, and 0.82, respectively) in the relation Rp ∝ Riα. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
105.
The structures of trimethylene oxide and sulphide have been studied by the nematic liquid crystal N.M.R. method. Corrections for the ring puckering motion have been applied and structures determined in conjunction with data from microwave spectroscopic studies. Improved results are obtained if a third motional constant is included in the analysis. 相似文献
106.
A new synthetic protocol for catalysing CO2 hydrogenation to formic acid under mild conditions is reported, and the CO2 hydrogenation is efficiently achieved by dcpe‐rhodium‐nitrosyl catalyst precursors, Rh(NO)(dcpe) (1) (dcpe = 1,2‐dicyclohexylphosphinoethane) and Rh(III)(NO)(dcpe)Cl2 (2). The catalytic activity of 1 is noteworthy for being able to proceed in the absence of protic conditions. Compound 2 is characterized by NMR, IR and X‐ray crystallography. In particular, 2 is observed to bear a bent NO ligand with a Rh–N–O angle of 115.7(3)°, representing one of the smallest M–N–O angles known. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
107.
Julian D. Cole 《Theoretical and Computational Fluid Dynamics》1998,10(1-4):91-104
The hodograph method is used to formulate several design problems in transonic flow using small-disturbance theory. Analytical
and numerical methods give solutions to several optimum critical airfoil designs with different constraints on the tail angle.
Special airfoil shapes flying at free-stream Mach number one are designed. The problem of constructing a shock-free body of
revolution at subsonic speed but having a supersonic zone is formulated in the hodograph and solved numerically.
Received 10 January 1997 and accepted 14 April 1997 相似文献
108.
109.
110.
R. Aryaeinejad E. L. Reber J. K. Jewell J. D. Cole M. W. Drigert 《Journal of Radioanalytical and Nuclear Chemistry》2005,264(1):155-162
Summary In this work, prompt gamma-rays emitted by thermal neutron-induced fission decay using fast coincidence techniques are used to identify both light and heavy fragments and obtain gamma-ray signatures and radiation multiplicity. The measurements were carried out with 235U and 239Pu targets using the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory. This study reports the recent results of a preliminary analysis of experimental data collected from the induced fission of 235U and 239Pu. In this paper, we discuss how these results could be used to characterize an unknown sample of fissile material. 相似文献