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91.
《Journal of Coordination Chemistry》2012,65(2):193-206
Interaction of dipropyltin(IV) with selected amino acids, peptides, dicarboxylic acids or DNA constituents was investigated using potentiometric techniques. Amino acids form 1?:?1 and 1?:?2 complexes and, in some cases, protonated complexes. The amino acid is bound to dipropyltin(IV) by the amino and carboxylate groups. Serine is complexed to dipropyltin(IV) with ionization of the alcoholic group. A relationship exists between the acid dissociation constant of the amino acids and the formation constants of the corresponding complexes. Dicarboxylic acids form both 1?:?1 and 1?:?2 complexes. Diacids forming five- and six-membered chelate rings are the most stable. Peptides form complexes with stoichiometric coefficients 111(MLH), 110(ML) and 11-1(MLH?1)(tin: peptide: H+). The mode of coordination is discussed based on existing data and previous investigations. DNA constituents inosine, adenosine, uracil, uridine, and thymine form 1?:?1 and 1?:?2 complexes and the binding sites are assigned. Inosine 5′-monophosphate, guanosine 5′-monophosphate, adenosine 5′-monophosphate and adenine form protonated species in addition to 1?:?1 and 1?:?2 complexes. The protonation sites and tin-binding sites were elucidated. Cytosine and cytidine do not form complexes with dipropyltin(IV) due to low basicity of the donor sites. The stepwise formation constants of the complexes formed in solution were calculated using the non-linear least-square program MINIQUAD-75. The concentration distribution of the various complex species was evaluated as a function of pH. 相似文献
92.
Yoshio Kobayashi Tsukasa Shirochi Takafumi Maeda Yusuke Yasuda Toshiaki Morita 《Surface and interface analysis : SIA》2013,45(9):1424-1428
This paper describes a metal–metal bonding technique using metallic Cu nanoparticles prepared in aqueous solution. A colloid solution of metallic Cu particles with a size of 54 ± 15 nm was prepared by reducing Cu2+ (0.01 M (CH3COO)2Cu) with hydrazine (0.6 M) in the presence of stabilizers (5 × 10?4 M citric acid and 5 × 10?3 M cetyltrimethylammonium bromide) in water at room temperature in air. Discs made of metallic materials (Cu, Ni/Cu, or Ag/Ni/Cu) were successfully bonded under annealing at 400 °C and pressurizing at 1.2 MPa for 5 min in H2 gas with help of the metallic Cu particle powder. Shear strength required for separating the bonded discs was 27.9 ± 3.9 for Cu discs, 28.1 ± 4.1 for Ni/Cu discs, and 13.8 ± 2.6 MPa for Ag/Ni/Cu discs. Epitaxial crystal growth promotes on the discs with a good matching for the lattice constants between metallic nanoparticles and metallic disc surfaces, which leads to strong bonding. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
93.
Pankaj Sehgal Manu Sharma Kim Lambertsen Larsen Reinhard Wimmer Hidekazu Doe Daniel E. Otzen 《Journal of Dispersion Science and Technology》2013,34(6):885-890
Interactions of γ-cyclodextrin (γ-CD) with the single and mixed micelles of sodium dodecyl sulfate (SDS) and sodium lauroyl sarcosine (SLAS) have been studied at different concentrations of γ-CD by using conductivity measurements. From conductivity data, the pure and mixed critical micellar concentration (cmc), the equivalent ionic conductivities of the monomeric species (Λ m), the associated species (Λ assc) and the micelle (Λ mic), the degree of counterion dissociation (χ) in the presence of γ-CD have been evaluated from the slope of the conductivity versus concentration plots for the pure and binary mixture of surfactants. From the dependence of cmc of the surfactantson γ-CD concentration, we have deduced the association constant (K) of surfactant-γ-CD inclusion complexes assuming 2:1 stoichiometry. Theories of Clint, regular solution, and Motomura's have been used for the evaluation of ideality or nonideality of the mixed system. Mixed micelles were found to be rich in SDS content in the presence and the absence of γ-CD. The cmc values have been used to evaluate the transfer of standard free energy of micelles (ΔG0 M,tr) from the aqueous medium to additive medium. 相似文献
94.
Pankaj Sehgal Manu Sharma Kim Lambertsen Larsen Reinhard Wimmer Daniel E. Otzen Hidekazu Doe 《Journal of Dispersion Science and Technology》2013,34(1):128-133
In this work, we have studied the influence of different concentrations of β‐Cyclodextrin (β‐CD) on the mixed micellization of anionic surfactants sodium dodecyl sulfate (SDS) and sodium lauroyl sarcosine (SLAS) at different SDS mole fractions (αSDS). From conductivity data, the critical micellar concentration (cmc), the equivalent ionic conductivities of the monomeric species (Λm), the associated species (Λassc) and the micelle (Λmic), the degree of counterion dissociation (α) in the presence of β‐CD were evaluated from the slope of the conductivity versus concentration plots for the pure and binary mixtures. The apparent cmc of the surfactants vary linearly with the β‐CD concentrations. From the dependence of cmc of the surfactants on β‐CD concentration, we have deduced the association constant (K) of surfactant‐β‐CD inclusion complexes assuming 1∶1 stoichiometry. Theories of Clint, Regular solution, and Motomura's have been used for the evaluation of ideality or nonideality of the mixed system. Mixed micelles were found to be rich in SDS content at the cmc in the presence and the absence of β‐CD. The cmc values have been used to evaluate the transfer of standard free energy of micelles (ΔG0 M,tr) from the aqueous medium to additive medium. 相似文献
95.
Two‐component relativistic density functional theory (DFT) with the second‐order Douglas–Kroll–Hess (DKH2) one‐electron Hamiltonian was applied to the calculation of nuclear magnetic resonance (NMR) shielding constant. Large basis set dependence was observed in the shielding constant of Xe atom. The DKH2‐DFT‐calculated shielding constants of I and Xe in HI, I2, CuI, AgI, and XeF2 agree well with those obtained by the four‐component relativistic theory and experiments. The Au NMR shielding constant in AuF is extremely more positive than in AuCl, AuBr, and AuI, as reported recently. This extremely positive shielding constant arises from the much larger Fermi contact (FC) term of AuF than in others. Interestingly, the absolute values of the paramagnetic and the FC terms are considerably larger in CuF and AuF than in others. The large paramagnetic term of AuF arises from the large d‐components in the Au dπ –F pπ and Au sdσ–F pσ molecular orbitals (MOs). The large FC term in AuF arises from the small energy difference between the Au sdσ + F pσ and Au sdσ–F pσ MOs. The second‐order magnetically relativistic effect, which is the effect of DKH2 magnetic operator, is important even in CuF. This effect considerably improves the overestimation of the spin‐orbit effect calculated by the Breit–Pauli magnetic operator. © 2013 Wiley Periodicals, Inc. 相似文献
96.
合成并表征了2个不对称大环双核铜配合物[Cu2(L1)Cl2]·CH3CN(1)和[Cu2(L2)Br2]·CH3CN·H2O(2)。配合物与CT-DNA的作用通过紫外-可见光谱,粘度实验,圆二色谱和凝胶电泳实验进行了研究。紫外-可见光谱的结果表明配合物与DNA的结合常数分别为6.2×105和7.2×105,圆二色谱的实验表明配合物能与DNA较好的结合,粘度实验表明配合物与DNA的结合为非典型的插入模式,凝胶电泳实验显示配合物通过氧化机理对DNA有较强的切割活性。 相似文献
97.
对于空心大球转子静电陀螺仪,转速接近静电支承系统(ESS)的剪切频率,一般采用磁场恒速控制方法,因而介绍了一种电场恒速控制方法,通过在支承电路中加入滤波器,来提高支承系统的力矩系数,从而利用支承系统构成了恒速控制系统。实验结果表明,系统的稳定性满足要求,恒速精度优于0.1Hz。 相似文献
98.
99.
TiNi形状记忆合金变形特性实验研究 总被引:2,自引:0,他引:2
给出了一种TiNi形状记忆合金(多晶)的单轴拉压、循环拉伸加卸载、形状记忆效果、恢复力、相变塑性变形及拉压。扭转比例、非比例加卸载的实验结果,实验结果显示,其变形特性非常不同于普通的弹塑性材料:如Bauschinger效果提前,甚至于会出现于卸载阶段;低温下的残余变形会在加热后消失;恒载下冷却时产生相当大的塑性变形(相变塑性变形)且在加热时消失等等。多轴加载实验结果表明,比例加载时该材料的加载屈服面及卸载屈服面都基本满足Mises准则,但非比例加载时则不然。 相似文献
100.
Eckhard Platen 《随机分析与应用》2015,33(4):573-608
We investigate the existence of affine realizations for Lévy driven interest rate term structure models under the real-world probability measure, which so far has only been studied under an assumed risk-neutral probability measure. For models driven by Wiener processes, all results obtained under the risk-neutral approach concerning the existence of affine realizations are transferred to the general case. A similar result holds true for models driven by compound Poisson processes with finite jump size distributions. However, in the presence of jumps with infinite activity we obtain severe restrictions on the structure of the market price of risk; typically, it must even be constant. 相似文献