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101.
We analyse the overall birefringence which arises from the combined effects of Faraday rotation (non-reciprocal) and bending stress (reciprocal) applied to a monomode optical fibre loop. The theory is substantiated by numerical evaluations and appropriate experimental data are reported. These indicate how it is possible to build non-reciprocal birefringent components, i.e. rotators and isolators, by means of monomode coils. 相似文献
102.
Marek L. Główka Henryk Krawczyk Ryszard Bodalski Valerio Bertolasi 《Journal of chemical crystallography》1989,19(4):701-705
The crystals (C16H18NO2P,M
r=287.30) are orthorhombic, space group Pbca witha=8.200(2),b=14.857(2), andc=24.396(5)Å,V=2972.1 Å3,Z=8,D
x=1.284 mg m–3,(MoK)=0.71069 Å,=1.90 cm–1,F(000)=216,T=295K. FinalR=0.044 for 1673 observed reflections collected on a diffractometer. Structure solved by direct methods.Cis-junction and double bond in the six-membered ring cause its almost ideal sofa conformation. The two neighboring methyl groups are cis, and cyano substituent is in an equatorial position. There is a shortintramolecular H(o-phenyl)O(endocyclic) contact of 2.53(3)Å and the phenyl ring is in a less favorable rotational orientation due to molecular packing. 相似文献
103.
C-Galactosyl and C-ribosyl β-amino acids were prepared by one-pot InCl3-catalyzed Mannich-type three-component condensation (3CC) by combining the corresponding formyl C-glycoside, p-methoxybenzyl amine, and a ketene silyl acetal. In each case the reaction was highly stereoselective and afforded only one single product in good to excellent yields. 相似文献
104.
Sandro Calogero Paolo Ganis Valerio Peruzzo Giuseppe Tagliavini 《Journal of organometallic chemistry》1980,191(2):381-390
The halogenocarboxylates (cyclo-C6H11)3SnO2CR′, (R′ = CH3, CH2Cl, CHCl2, CCl3 and CF3) have been prepared, and characterized by Mössbauer and IR spectroscopy. The crystal structure of (cyclo-C6H11)3SnO2CCF3 has been determined by X-ray analysis. The crystals are orthorhombic, space group Pcmn, with unit cell parameters a 14.390 ± 0.004, b, 13.427 ± 0.004, c 11.516 ± 0.003 Å. The structure was resolved by Patterson methods and refined to an R value of 0.147. The coordination about the tin atom can be considered distorted trigonal-pyramidal or distorted tetrahedral. Mössbauer data are explained in terms of distortions of bond angles about the tin atom. 相似文献
105.
Ulderico Mazzi Edoardo Roncari Roberto Rossi Valerio Bertolasi Orazio Traverso Luciano Magon 《Transition Metal Chemistry》1980,5(1):289-293
Summary The reactions of ReOX3(PPh3)2 (X = CI or Br) withN-methylsalicylideneimine (Me-saIH),N-phenylsalicylideneimine (Ph-saIH),N,N-ethylenebis(salicyli(leneimine) [(SaIH)2en] and 8-hvdroxyquinoline (Oxinell) are here reported. They give rise to the ReOX2(Me-sal)PPh2. ReOX-(Me-sal)2, ReOX2(Ph-sal)PPh3, ReOX(Ph-sal),, Re2O2X4-(Sal2en)(PPh3)2, ReOX2(Oxine)PPh, and ReOX(Oxine)2 complexes. 相似文献
106.
Giuliana Biagi Irene Giorgi Oreste Livi Federica Pacchini Valerio Scartoni Oreste Leroy Salerni 《Journal of heterocyclic chemistry》2004,41(4):575-580
A suitably substituted pyrimidine 1 was converted to a number of title compounds. Nucleophilic substitu tion involving the chlorine atoms in 1 by treatment with phenylmethanethiol yielded 2 or 3 , depending on the reaction temperature. Treatment of 3 with an amine afforded 6‐phenylmethanesulfanyl‐N4‐substituted‐2‐phenyl‐pyrimidine‐4,5‐diamines 4–7 . These pyrimidines were converted into 2‐phenylpurines 8–11 and 2‐phenyl‐8‐azapurines 12–14 , by treatment with triethyl orthoformate in the presence of hydrochloric acid (or acetic anhydride), or with potassium nitrite and acetic acid respectively. The thioether function on C(6) was then converted into a sulfonyl group by oxidation with m‐chloroperoxybenzoic acid affording purines 15–18 and their 8‐azaanalogs 19–21 ; these compounds, as crude products, were treated with an amine to yield the corresponding adenines 22–25 or 8‐azaadenines 26–31. All reactions were performed under conditions com patible with the possible use of a thiomethyl resin in place of phenylmethanethiol to bind the pyrimidine ring of 1 to a solid phase. 相似文献
107.
Valerio Di Lisio Elisa Sturabotti Iolanda Francolini Antonella Piozzi Andrea Martinelli 《Journal of Polymer Science.Polymer Physics》2019,57(3):174-181
The effect of the annealing few degrees above the glass transition temperature (Tda = 62 °C) on the physical aging (Tpa = 51 °C) of amorphous quenched poly(l ‐lactide) is investigated by an implementation of variable temperature Fourier transform infrared (FTIR). By using a temperature program composed of a linear heating ramp superimposed to a temperature modulation (modulated temperature FTIR), the reversing and nonreversing intensity variation of selected bands, related to high‐energy gg and low‐energy gt conformers, is investigated. It is observed that the annealing above T g changes irreversibly the conformation distribution of the liquid polymer. The glasses obtained from annealed and nonannealed liquids behave differently, evolving in the physical aging toward their own liquid state and retaining the memory of their original condition before the vitrification. The recovery through T g of the relaxation occurred in the physical aging depends not only from aging conditions but also by the thermal history of the sample above the Tg. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 174–181 相似文献
108.
109.
Valerio Faraoni 《General Relativity and Gravitation》2010,42(4):851-860
Harrison’s argument against the interpretation of the cosmological redshift as a Doppler effect is revisited, exaggerated,
and discussed. The context, purpose, and limitations of the interpretations of this phenomenon are clarified. 相似文献
110.
The synthesis of 1,4-dihydro-2-methyl- and 1,4-dihydro-1,2-dimethyl-4-oxo-nicotinic acids was accomplished following a route other than Ochiai's procedure, which yielded the isomer 1,6-dihydro-2-methyl-6-oxo-nicotinic acid ethyl ester, and not the 4-oxo-derivative, as reported. Analytical data confirmed the identity of the two isomer oxo-nicotinic acids. UV-vis and potentiometric preliminary data showed that Al(III) does not form complexes with 1,6-dihydro-2-methyl-6-oxo-nicotinic acid ethyl ester in solution, as expected, but with 1,4-dihydro-2-methyl-4-oxo-nicotinic acid. 相似文献