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621.
An asymptotic method of analysis of fluctuations in systems far from equilibrium is developed. A systematic singular perturbative expansion of the equation for the generating function is set up, using as smallness parameter the inverse of the size of the system. Static and time-dependent properties are analysed before, near and at a bifurcation point, both for homogeneous and inhomogeneous fluctuations. The connection with critical phenomena near equilibrium is also discussed. 相似文献
622.
M. Mansour 《International Journal of Theoretical Physics》1998,37(9):2403-2408
This paper describes the infinite oscillatoralgebra deformation along the lines of thestar-deformation method. Realization of a q-deformedcenterless Virasoro algebra and SUq(2)algebra are obtained. 相似文献
623.
624.
The effect of deformation on the nucleus-nucleus optical model potential and how it produces pockets
M. Ismail M. Rashdan Amand Faessler M. Trefz H. M. M. Mansour 《Zeitschrift für Physik A Hadrons and Nuclei》1986,323(4):399-405
A recently derived nucleon-nucleon interaction has been used to calculate both the real and imaginary parts of the optical-model potential for the two nuclear pairs Pb+U and U+U. Three different bombarding energies per projectile nucléon (6 MeV, 11.8 MeV and 20.9 MeV) have been considered. We found a dramatic dependence of both the real and imaginary parts of the optical-model potential on relative orientation of the colliding nuclei. For the two considered pairs we predicted pockets whose depths depend strongly on orientation. 相似文献
625.
626.
627.
The mononuclear Au(I) complex, Au(Spy)(PPh2py) (1), has been synthesized and characterized structurally. The complex possesses the expected linear coordination geometry with a S-Au-P bond angle of 176.03(6) degrees and no evidence of aurophilic interactions between nearest neighbor Au(I) ions in the solid state. Protonation of the pendant pyridyl groups of 1 leads to the formation of the H-bonded dimer [(Au(SpyH)(PPh2py))2](PF6)2 (2), which has also been structurally characterized. A linear coordination geometry at the Au(I) ions in 2 with a S-Au-P bond angle of 173.7(2) degrees is augmented by evidence of a strong aurophilic interaction with a Au...Au distance of 2.979(1) A. The pendant pyridyl groups of 1 have also been used to bind Cu(I) by reactions with [Cu(NCMe)4](PF6) and Cu(P(p-tolyl)3)2(NO3) leading to the formation of the heterobimetallic complexes [(AuCu(mu-Spy)(mu-PPh2py))2](PF6)2 (3) and [AuCu(P(p-tolyl)3)2(mu-Spy)(mu-PPh2py)](NO3) (4), respectively. A structure determination of 3 reveals a tetranuclear complex composed of two AuCu(mu-Spy)(mu-PPh2py)+ units held together by bridging thiolate ligands. A strong metal-metal interaction is noted between the two different d10 ions with nearest Au-Cu distances averaging 2.6395 A. The S-Au-P bond angles in 3 deviate slightly from linearity due to the Au...Cu interactions, while the coordination geometries at Cu(I) are distorted tetrahedral consisting of the two pyridyl nitrogen atoms, a bridging thiolate sulfur, and the interacting Au(I) ion. While mononuclear complex 1 is only weakly emissive in the solid state and in fluid solution, complexes 2-4 show stronger photoluminescence in the solid state and rigid media at 77 K, and in fluid solution. The emission maxima for 2-4 in ambient temperature fluid solution are 470, 635, and 510 nm, respectively. A tentative assignment of the emitting state as a S(p pi)-->Au LMCT transition is made on the basis of previous studies of Au(I) thiolate phosphine complexes. Shifts of lambda em result from the influence of H bonding or Cu(I) coordination on the filled thiolate orbital energy, or on the effect of metal-metal interaction on the Au(I) acceptor orbital energy. Crystal data for Au(Spy)(PPh2py) (1): triclinic, space group P1 (No. 2), with a = 8.3975(4) A, b = 11.0237(5) A, c = 12.4105(6) A, alpha = 98.6740(10) degrees, beta = 105.3540(10) degrees, gamma = 110.9620(10) degrees, V = 995.33(8) A3, Z = 2, R1 = 3.66% (I > 2 sigma(I)), wR2 = 9.04% (I > 2 sigma(I)) for 2617 unique reflections. Crystal data for [(Au(SpyH)(PPh2py))2](PF6)2 (2): triclinic, space group P1 (No. 2), with a = 14.0284(3) A, b = 14.1093(3) A, c = 15.7027(2) A, alpha = 97.1870(10) degrees, beta = 96.5310(10) degrees, gamma = 117.1420(10) degrees, V = 2692.21(9) A3, Z = 2, R1 = 7.72% (I > 2 sigma(I)), wR2 = 15.34% (I > 2 sigma(I)) for 5596 unique reflections. Crystal data for [(AuCu(mu-Spy)(mu-PPh2py))2](PF6)2 (3): monoclinic, space group P2(1)/c (No. 14), with a = 19.6388(6) A, b = 16.3788(4) A, c = 17.2294(5) A, beta = 91.48 degrees, V = 5540.2(3) A3, Z = 4, R1 = 3.99% (I > 2 sigma(I)), wR2 = 8.38% (I > 2 sigma(I)) for 10,597 unique reflections. 相似文献
628.
The radiosensitivity of codling moth, Cydia pomonella (L.), eggs in different stages of development was studied. Eggs ranging in age from 1–24 to 97–120 h were exposed, at 24 h intervals, to gamma radiation doses ranging from 10 to 350 Gy. The effects of gamma radiation on egg hatch, pupation and adult emergence was examined. Results showed that the radiosensitivity of codling moth eggs decreased with increasing age. Egg hatch in 1–24 h old eggs was significantly affected at 20 Gy dose and at 60 Gy dose, egg hatch decreased to about 1%. At the age of 25–48 h, however, egg hatch at 60 Gy dose was about 10%, and egg sensitivity to gamma irradiation decreased significantly in the 49–72 h age group; 60 Gy dose had no significant effect on egg hatch. Eggs irradiated few hours before hatch (at the blackhead stage), were the most resistant ones; 100 Gy had no significant effect on egg hatch and at 350 Gy dose over 56% of the eggs hatched. When adult emergence was used as a criterion for measuring effectiveness, however, the effect of gamma radiation was very sever. A dose of 60 Gy completely prevented adult emergence and at 100 Gy dose all resulted larvae died before pupation. 相似文献
629.
Robert W. Hay Mansour M. Hassan David E. Fenton Brian P. Murphy 《Transition Metal Chemistry》1994,19(5):559-560
Summary The kinetics of the acid dissociation of the copper(II) complex of the 15-membered N3O2 donor macrocycle [prepared by reaction of 2,6-bis(2-aminophenoxymethyl)-pyridine with glyoxal in the presence of a manganese(II) template followed by reduction of the two imine linkages with NaBH4] was studied over an acidity range (0.01–0.5 mol dm-3 [H+]) at 25 °C and I = 1.0 mol dm-3 by stopped-flow methods. A biphasic reaction was observed at 752 nm, the first reaction being complete within 20 ms at 25 °C and too rapid to study in detail. The second reaction shows a good first order dependence on the hydrogen ion concentration over the whole acidity range and k
obs=k0+k
H[H+], where k
0 = 0.52 s-1 and k
H = 40.2 dm3 mol-1 s-1 at 25 °C. The k
0 term represents a small but significant solvolytic reaction. The mechanism of the acid-catalysed dissociation is discussed. 相似文献
630.
A one-step synthesis of 2-methylthio-6-oxopyrimidine derivatives: Preparation of fused pyrimidinones
Condensation of a ternary mixture of ethyl cyanoacetate, S-methylisothiourea and aromatic aldehydes in pyridine afforded directly the 4-aryl-5-cyano-2-methylthio-6-oxopyrimidines IV in good yields. Alkylation of IV with alkyl halides in alkaline medium yielded the 1-alkyl derivatives V. The methylthio group in IV and V could be eliminated by aniline, hydrazine and phenylhydrazine and the corresponding 2-anilino, VII, 2-hydr-azino, VIIIa,b, and 2-phenylhydrazino, VIIIc,d, derivatives were obtained. Compounds VIIIa,b could be cyclised with nitrous acid to give the 3-cyano-4-phenyltetrazolo[1,5-a]pyrimidine-2-one (Xa) and the 1-methyl analogue Xb, respectively. Some derivatives of VIII were prepared to help in elucidating the structures. 相似文献