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71.
Sandra Di Rocco 《manuscripta mathematica》1996,91(1):35-59
Let
be the set of surfaces,S, polarized by a k-very ample line bundle,L, with genus≤3k+1. All the elements (S, L) of
are listed. The classification of surfaces polarized by ak-very ample line bundle of degree ≤4k+4 is completed by proving that this class of surfaces is a subset of
. 相似文献
72.
Rocco J. A. F. F. Lima J. E. S. Frutuoso A. G. Iha K. Ionashiro M. Matos J. R. Suárez-Iha M. E. V 《Journal of Thermal Analysis and Calorimetry》2004,77(3):803-813
Thermal decomposition kinetics of solid rocket propellants based on hydroxyl-terminated polybutadiene-HTPB binder was studied
by applying the Arrhenius and Flynn-Wall-Ozawa's methods. The thermal decomposition data of the propellant samples were analyzed
by thermogravimetric analysis (TG/DTG) at different heating rates in the temperature range of 300-1200 K. TG curves showed
that the thermal degradation occurred in three main stages regardless of the plasticizer (DOA) raw material, the partial HTPB/IPDI
binder and the total ammonium perchlorate decompositions. The kinetic parameters E
a (activation energy) and A (pre-exponential factor) and the compensation parameter (S
p) were determined. The apparent activation energies obtained from different methods showed a very good agreement.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
73.
A series of 7-amino-1-cyclopropyl-1,4-dihydro-8-fluoro-4-oxo-1,6-naphthyridine-3-carboxylic acids has been prepared and evaluated for antibacterial activity. These compounds were prepared by the displacement of the chloro substituent from 7-chloro-1-cyclopropyl-1,4-dihydro-8-fluoro-4-oxo-1,6-naphthyridine-3-carboxylic acid employing the requisite nitrogen nucleophile to produce the title compounds. The naphthyridine acid was synthesized in ten steps from ethyl 2,4-dihydroxy-3-nitro-5-pyridinecarboxylate. The key step in the sequence was a Schiemann reaction carried out using the hexafluorophosphate salt of the diazonium ion derived from ethyl 3-amino-2,4-dichloro-5-pyridinecarboxylate. 相似文献
74.
Ch. Ristori P. A. Hervieux M. Maurel H. J. Andrä A. Brenac J. Crançon G. Lamboley Th. Lamy P. Perrin J. C. Rocco F. Zadworny B. A. Huber 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,22(1):425-430
We report on measurements of angular differential cross sections for the excitation of multiply charged ions by electron impact. An ion beam is crossed by an electron beam; electrons which are inelastically scattered at different angles are identified by their energy loss due to the excitation process. Absolute excitation cross sections are obtained by comparing the signals of the elastic and the inelastic electron-ion scattering. Results obtained for the 3s→3p excitation of Ar7+ are discussed. 相似文献
75.
Rocco Alessio Daniela Belli Dell'Amico Fausto Calderazzo Ulli Englert Alessandro Guarini Luca Labella Peter Strasser 《Helvetica chimica acta》1998,81(2):219-230
The reaction of CuO'Bu with CO2, and iPr2NH in the presence of PPh3, gives the dialkylcarbamato complex [Cu(O2CNiPr2)(PPh3)2] ( 1 ). The CO2/R2NH system (R = Me, Et) in an appropriate organic medium reacts with Ag2O giving the corresponding N,N-dialkylcarbamato complexes of analytical formula [Ag(C2CNR2)] (R = Me, 2 ; R = Et, 3 ). The methyl derivative 2 was characterized by X-ray diffraction methods. Crystal data of 2 : for [Ag2(O2CNMe2)2], C6H12Ag2N2O4, mol. wt. 391.9; monoclinic, space group P21/c, a = 12.08(1), b = 3.797(2), c = 11.316(7) Å, β = 113.37(6)°, V = 476.3 Å3, Z = 2, Dc = 2.732 g cm?3; μ(MoKα) = 40.64 cm?1, F(000) = 376.0; R = 0.059, Rw = 0.067; g.o.f. 1.27. The structure consists of dinuclear [(Ag2OCNMe2)2] units with slightly distorted linearly two-coordinated Ag-atoms containing bridging carbamato groups to form a substantially planar eight-membered ring with an intra-annular Ag? Ag distance of 2.837(2) Å; the dinuclear units are further joined by Ag? O bonds to form an infinite array. Compound 3 , which is presumably dinuclear, as suggested by cryoscopic measurements in benzene, undergoes a structural fission with PPh3, giving the mononuclear triphenylphosphine derivative [Ag(O2CNEt2)(PPh3)2] ( 4 ). The amine-catalyzed conversion of Ag2O into Ag2CO3, in the presence of the iPr2NH/CO2 system, is also reported. Cl-Exchange from [AuCl(PPh3)] with [Ag(O2CNEt2)] ( 3 ) gives the first N,N-dialkylcarbamato complex of gold, namely [Au(O2CNEt2)(PPh3)] ( 5 ), which crystallizes in the monoclinic system: C23H25AuNO2P · 0.5 C7H16, mol. wt. 625.5, space group P21/c; a = 13.212(5), b = 12.25(1), c = 16.795(6) Å, β = 109.09(2)°, V = 2568(2) Å3, Z = 4, Dc, = 1.618 g cm?3; μ(AgKα) = 31.40 cm?1, F(000) = 1236.0; R = 0.058; Rw = 0.064; g.o.f. 2.121. The compound contains two-coordinated Au-atom, namely to the P-atom and to the O-atom of the monodentate carbamato group, the P? Au? O bond angle being 174.7(3)°. The reaction with MeI showed these compounds to react predominantly at the carbamato O-atom giving the corresponding urethanes R2NCO2Me. Evidence was gathered for the transient coordination of CO to Ag in 3 . 相似文献
76.
The thiourea group has been exploited to link two or four carbohydrate units at the upper rim of tetrapropoxycalix[4]arene derivatives in the cone conformation. Two synthetic methodologies were used, the first one consisting of the condensation of di- and tetraminocalix[4]arenes with the isothiocyanate of monosaccharides in dry CH2Cl2 at room temperature and the second one exploiting the condensation of an aminolactoside with a calixarene isothiocyanate. The first method allows the glycoconjugates to be obtained in 75-80% overall yields. The disfunctionalized derivatives exist in a closed flattened cone conformation in CDCl3 and CD3OD due to the formation of intramolecular hydrogen bonds involving the thiourea groups which are broken in DMSO-d6 to give an open flattened cone conformation. The thiourea groups act not only as linkers but also as binding units for anionic substrates as evidenced by solution 1H NMR and ESI-MS experiments. Turbidimetric analysis indicates that the tetraglucoside and tetragalactoside clusters give specific interactions with Concanavalin A (Con A) and peanut lectin (PNA), respectively. Both features show that the neoglycoconjugates could also be used as site specific molecular delivery systems. 相似文献
77.
F. Bredice F.O. Borges H. Sobral M. Villagran-Muniz H.O. Di Rocco G. Cristoforetti S. Legnaioli V. Palleschi A. Salvetti E. Tognoni 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007
We present measurements of the Stark broadening of several Mn lines in the conditions of typical laser-induced plasmas. Single-and double-pulse Laser-Induced Breakdown spectroscopy (LIBS) configurations are studied on a series of Fe–Mn alloy samples with Mn concentration ranging from 6% to 30%. The effects of self-absorption on the measured line broadenings are discussed in detail. In particular, the experimental results evidence that self-absorption is much higher in laser-induced plasmas generated with double pulses, compared to the case of single pulse. After measurement of the electron density, the Stark coefficients of several neutral and ionic Mn lines are derived through the measure of the broadening in conditions of optically thin plasma. The results obtained for singly ionized Mn lines are compared with the theoretical and experimental data present in the literature. For the first time, experimental measurements of the Stark coefficient for several neutral Mn lines are also presented. 相似文献
78.
F. Bredice H. Sobral M. Villagran-Muniz H.O. Di Rocco G. Cristoforetti S. Legnaioli V. Palleschi A. Salvetti E. Tognoni 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007
A Nd:YAG laser pulse was focused, in air or on a Cu target, between the plates of a planar charged capacitor. The plasma generates a transient redistribution of the electrical charges on the plates that can be easily measured as a voltage drop across a resistor connected to the ground plate. At the same time, the Stark broadening of the Hα spectral line (656.3 nm) obtained from the optical emission spectrum of the plasma was measured. In this work, we show that the peak of electrical signal measured on the resistor is, in the energy range of our laser (30 mJ to 220 mJ) and at time delays typical of Laser-Induced Breakdown Spectroscopy applications (500–5000 ns), univocally related to the temporal evolution of the Stark broadening of the Hα line. Therefore, after a proper calibration depending on the material and the experimental geometry, the peak of the electrical signal can be used to predict the temporal evolution of the electron density of the generated plasma. 相似文献
79.
80.