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91.
92.
We have studied the mean free path of He fragments from projectile beams of Ar, Fe and Kr of energy 1 ? E ?2A GeV at different distances from their production point and found that they are the same, independent of their (i) energy, (ii) target size, (iii) target excitation, (iv) He multiplicities and (v) production angles. 相似文献
93.
C. Jagannath E.R. Youngdale D.M. Larsen R.L. Aggarwal P.A. Wolff 《Solid State Communications》1982,43(4):267-270
The technique of four-wave mixing spectroscopy has been utilized to study the magnetic field dependence of the valley-orbit splitting, 4△(B), of As donors in Ge at 1.8°K for ⊥ [111]. The upper ground level, ls(T2), splits into two levels, one of “high” and the other of “low” diamagnetism. For donor concentration ND ? 5 × 1015 cm-3 we have measured the diamagnetism and g-factor for the high diamagnetism level (g ? 1.07) as a function of (< 7 T). Transitions originating from both spin-up and spin-down levels are observed, indicating that the spins are heated during the 100 n-sec laser pulse. Excellent agreement between measured and theoretical values of 4▽(B) is found (employing no adjustable parameters) if magnetic field compression of the wavefunction is taken into account. 相似文献
94.
95.
It is analytically shown that the position of the Fourier transform of the speckle pattern produced by a coherently illuminated, diffusely reflecting surface depends upon its angle of illumination. A method is proposed to measure small changes in this angle by doubly exposing the photographic plate with the original and laterally displaced Fourier transforms of the object speckle. The method is well suited for accurate measurements of the wedge angle and tilt of optical surfaces and to determine variations in refractive index or temperature of axially symmetric phase objects. 相似文献
96.
97.
Sanz D Claramunt RM Singh SP Kumar V Aggarwal R Elguero J Alkorta I 《Magnetic resonance in chemistry : MRC》2005,43(12):1040-1043
The combined use of 1H NMR spectroscopy with theoretical calculations of chemical shifts (GIAO) and coupling constants (B3LYP/6-311 ++G**) of a 5-hydroxy-5-trifluoromethyl-Delta2-isoxazoline has enabled solving the problem of the assignments of the diastereotopic protons in this compound. This result has been extended to 5-hydroxy-5-trifluoromethyl-Delta2-pyrazolines and the corresponding 5-trichloromethyl derivatives. 相似文献
98.
Metal(II) complexes of N-(thiophene-2-carboxamido)salicylaldimine (H2TCS) of types M(H2TCS)2Cl2 [M = Ni, Cu and Zn], M(HTCS)Cl [M = Co, Ni and Cu], M(HTCS)2 [M = Mn, Fe, Co, Ni, Cu and Zn], M(TCS)·xH2O [M = Mn, Co and Ni, x = 2; M = Cu, x = 0], Ni(TCS)py2 and Cu(TCS)py have been prepared. Elemental analyses, molar conductance, magnetic moment, electronic, IR and ESR spectral studies have been used to characterize these complexes. The different modes of chelation of the ligand and the stereochemistry of the complexes are discussed. 相似文献
99.
100.
Aggarwal LP Borissevitch IE 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,63(1):227-233
The dynamics of aggregation of meso-tetrakis (p-sulfonatofenyl) porphyrin (TPPS4) in function of its concentration, pH and ionic strength was studied by optical absorption, fluorescence and resonance light scattering (RLS) techniques. In the region of pH, where TPPS4 exists in biprotonated form, the addition of NaCl induces the TPPS4 aggregation due to the formation of the "cloud" of counter ions around the TPPS4 molecule thus reducing electrostatic repulsion between the porphyrin molecules. The formation of this "cloud" shifts the pKa value to acid region (from 5.0 in the absence of salt to 4.5 at [NaCl] = 0.4 M), reduces the TPPS4 absorption in all spectral range and quantum yield and lifetime of fluorescence (from 0.27 to 0.17 and from 4.00+/-0.04 to 3.00+/-0.03 ns in the absence of salt and in the presence of NaCl, respectively). The aggregation process involves two successive stages: initially H aggregates are formed, which in time are transformed in J ones. The existence of these two stages was confirmed by the fluorescence and RLS data. The kinetics of the formation of J aggregates is characterized by the induction time t1 and the average growth time t2, which depend on both TPPS4 and salt concentrations. The induction period t1 appears as a result of initial formation of H aggregates and their successive transformation in J ones. At very high TPPS4 concentrations, the J aggregates are united in more complex structures such as hollow cylinders or helixes. 相似文献