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31.
本文提出了铀(Ⅵ)-5-Br-PADAP-磺基水杨酸三元配合物的极谱配位吸附波。在pH为7.5-8.2的醋酸、三乙醇胺、乙醇底液中,该波的峰电位在-0.6855V(vs.SCE)。在1.00×10UP>-7UP>-1.00×10UP>-5UP>mol·dmUP>-3UP>范围内,铀(Ⅵ)浓度与峰电流呈线性关系。对极谱波的电流、电位性质进行了研究,测定了配合物的组成、表观稳定常数和离解及生成速率常数。 相似文献
32.
Lorraine P. McDonnell Bushnell Eric R. Evitt Robert G. Bergman 《Journal of organometallic chemistry》1978,157(4):445-456
Reactions of η5-cyclopentadienylbis(triphenylphosphine)cobalt(I) (5) with several 2,n-alkadiynes (2) were investigated. Each of these reactions leads initially to a material in which one of the acetylene functional groups is π-coordinated to cobalt; this complex then undergoes conversion to a metallocycle. In cases where the two acetylene functions are connected by three- and four-carbon bridges (2b, 2c), metallocycles formed by intramolecular reaction of two acetylene functions in the same molecule may be isolated. In cases where the acetylene functions are joined by larger or smaller bridges, the reactions are more complex, and both inter- and intramolecular metallocycles are formed. Reactions of 5 with 1,8-bis(trimethylsilyl)-1,7-octadiyne (16) gives an isolable crystalline mono-acetylene complex (17), this material is stable in the solid state but undergoes conversion to metallocycle (18) in benzene solution. The relationship of these results to the mechanism of the CpCo(CO)2-catalyzed benzocycloalkene synthesis is discussed; it is suggested that intramolecular metallocycles are intermediates in reactions leading to benzocyclopentanes and -cyclohexenes, but intermolecular metallocycles are probably involved in reactions leading to benzocyclobutenes. 相似文献
33.
E.H. Appelman B. Beagley D.W.J. Cruickshank A. Foord S. Rustad V. Ulbrecht 《Journal of Molecular Structure》1976,35(1):139-148
The molecular structure of FBrO3 has been studied by gas-phase electron diffraction. Least-squares refinements of the molecular geometry using fixed spectroscopic amplitudes revealed two geometrical minima. Initially, the amplitudes employed were derived from diagonal force fields obtained by spectroscopic least-squares refinements to fit observed and calculated wave numbers; for each geometry there are two spectroscopic minima. In the lowest geometrical minimum the wave number agreement is poor, however, the introduction of the ∠OBrO/∠FBrO interaction force constant removed the discrepancies; the resulting force field is F(Br-O) = 6.92 ± 0.02 mdyn Å?1F(Br-F) = 3.22 ± 0.03 mdyn Å?1, F(∠OBrO) = 1.06 ± 0.02 mdyn Å, F(∠FBrO) = 0.81 ± 0.03 mdyn Å, F(∠OBrO/∠FBrO) = ?0.19 ± 0.02 mdyn Å. In the corresponding geometrical minimum rg(Br-O) = 1.582 ± 0.001 Å, rg(Br-F) = 1.708 ± 0.003 Å, rα(∠OBrO) = 114.9 ± 0.3°, rα(∠FBrO) = 103.3 ± 0.3°. Perpendicular amplitude correction coefficients, calculated for each force field employed, were used throughout to relate the interatomic distances through the rα-structure. The geometries of the rαo- and re-structures are estimated. 相似文献
34.
Bromoacetyl chloride and bromoacetyl bromide are studied by gas phase electron diffraction at nozzle-tip temperatures of 70°C and 77°C, respectively. Both compounds exist as mixtures of anti and gauche conformers. The mole fraction anti, with uncertainties estimated at 2σ, was found to be 0.474(0.080) for bromoacetyl chloride and 0.615(0.069) for bromoacetyl bromide. The results for the distance (ra)and angle (∠α) parameters, with parenthesized uncertainties of 2σ including estimated uncertainty in the electron wave length and correlation effects are as follows: (1) bromoacetyl chloride, r(C-H) = 1.086(0.062) Å, r(CO) = 1.188(0.009) Å, r(C-C) = 1.519(0.018) Å, r(C-Cl) = 1.789(0.011) Å, r(C-Br) = 1.935(0.012) Å, ∠C-CO = 127.6(1.3)°, ∠C-C-Cl = 111.3(1.1)°, ∠C-C-Br = 111.0(1.5)°, ∠H-C-H = 109.5°(assumed), /o (gauche torsion angle relative to 0° for the anti form) = 110.0°(assumed); (2) bromoacetyl bromide, r(C-H) =1.110(0.088) Å, r(C=O) = 1.175(0.013) Å, r(C-C) = 1.513(0.020) Å, r(CO-Br) = 1.987(0.020) Å, r(CH2-Br) = 1.915(0.020) Å, ∠C-CO = 129.4(1.7)°, ∠CH2-CO-Br = 110.7(1.5)°, ∠CO-CH2-Br = 111.7(1.8)°, ∠H-C-H = 109.5°(assumed), ∠ø (gauche torsion angle relative to 0° for the anti form) = 105.0°(assumed). The structural results are discussed in connection with the structures of related molecules. 相似文献
35.
The reactions of Fe(CO)5, Fe(CO)4P(C6H5)3, M(CO)6 (M W, Mo, Cr), and (CH3C5H4Mn(CO)3 with KH and several boron and aluminium hydrides were investigated. Iron pentacarbonyl was converted quantitatively to K+Fe(CO)4-(CHO) by hydride transfer from KBH(OCH3)3 allowing isolation of [P(C6H5)3]2-Nn+Fe(CO)4(CHO)? in 50% yield. Lower yields were obtained with LiBH(C2H5)3, and other hydride sources gave little or no formyl product. The stability of Fe(CO)4(CHO)? in THP was found to depend on the cation, decreasing in the order [P(C6H5)3]2N+ > K+ > Na+ > Li+. No formyl complexes were isolated and no spectroscopic evidence for formyl formation was observed in the reactions of the other transition metal carbonyls with several hydride sources. Fe(CO)4-P(C6H5)3 gave K2Fe(CO)4 when treated with KHB(OCH3)3. When treated with LiBH(C2H5)3, W(CO)6 gave a mixture of HW2(CO)10?and (OC)5W(COC2H5)?; the latter was methylated to give the carbene complex (OC)5WC(OCH3)C2H5. 相似文献
36.
Dhanpat Rai Yuanxian Xia Linfeng Rao Nancy J. Hess Andrew R. Felmy Dean A. Moore David E. McCready 《Journal of solution chemistry》2005,34(4):469-498
The objectives of this study were to address uncertainties in the solubility product of (UO2)3(PO4)2⋅4H2O(c) and in the phosphate complexes of U(VI), and more importantly to develop needed thermodynamic data for the Pu(VI)-phosphate system in order to ascertain the extent to which U(VI) and Pu(VI) behave in an analogous fashion. Thus studies were conducted on (UO2)3(PO4)2⋅4H2O(c) and (PuO2)3(PO4)2⋅4H2O(am) solubilities for long-equilibration periods (up to 870 days) in a wide range of pH values (2.5 to 10.5) at fixed phosphate concentrations of 0.001 and 0.01 M, and in a range of phosphate concentrations (0.0001–1.0 M) at fixed pH values of about 3.5. A combination of techniques (XRD, DTA/TG, XAS, and thermodynamic analyses) was used to characterize the reaction products. The U(VI)-phosphate data for the most part agree closely with thermodynamic data presented in Guillaumont et al.,(1) although we cannot verify the existence of several U(VI) hydrolyses and phosphate species and we find the reported value for formation constant of UO2PO−4 is in error by more than two orders of magnitude. A comprehensive thermodynamic model for (PuO2)3(PO4)2⋅4H2O(am) solubility in the H+-Na+-OH−-Cl−-H2PO−4-HPO2−4-PO3−4-H2O system, previously unavailable, is presented and the data shows that the U(VI)-phosphate system is an excellent analog for the Pu(VI)-phosphate system. 相似文献
37.
The microwave spectrum of N2D4 has been observed and analyzed. Based on five low-J rotational transitions the effective rotational constants are: A = 74712.9 ± 1.9 MHz, B = 18500.42 ± 0.46 MHz, and C = 18439.91 ± 0.46 MHz. The quadrupole coupling constants of the 14N nuclei are Xaa = 4.23 ± 0.04 MHz, Xbb = 1.98 ± 0.05 MHz, and Xcc = ?2.25 ± 0.05 MHz. Using the observed ground state inversion splittings for N2D4 and N2H4 the barrier to inversion of a single amino group is computed to be 5.00 kcal mol?1. 相似文献
38.
The Electron impact mass spectra of (CO)3 MC6H5—X complexes (M = Cr, W; X = OCH3, OC4H9, CO2CH3, CO2C4H9) were recorded. From metastable transitions and by high-resolution measurements complete fragmentation diagrams were obtained; in some cases comparative structure determinations of fragment ions were carried out by collisional activation. The fragmentation of the tungsten complexes considerably differs from that of the chromium compounds. The differences may be attributed to the stronger-electrophilic character as well as to the more pronounced tendency of tungsten to attain higher oxidation states. 相似文献
39.
The paper analyses the convergence of sequences of control polygons produced by a binary subdivision scheme of the form
相似文献
40.
Conclusion Nous espérons avoir convaincu le lecteur qu'il peut être utile de considérer la classe de Maslov comme une classe bornée. Dans [Gh], nous avons montré que la classe d'Euler bornée pour un groupe d'homéomorphismes directs du cercle rend compte de la dynamique topologique de ce groupe. Existe-t-il un résultat analogue pour Sp(2n,)? En d'autres termes, soit un groupe discret et 1, 2 deux représentations de dans Sp(2n,). On suppose que les cocycles
1
*
et
2
*
définissent la même classe bornée. Que peut-on en conclure sur 1 et 2?Par ailleurs, l'article [At l] traite aussi d'invariants sur SL(2,) différents de ceux que nous avons considérés, comme par exemple les fonctionsL de Shimizu. Est-il possible de les faire rentrer naturellement dans notre cadre?
相似文献 |