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991.
Thermal runaway evaluation of α-methylstyrene and trans-β-methylstyrene with benzaldehyde 总被引:2,自引:2,他引:0
S. -Y. Lin J. -M. Tseng M. -K. Lee T. -C. Wu C. -M. Shu 《Journal of Thermal Analysis and Calorimetry》2009,95(2):559-563
Styrene is an important chemical in the petrochemical industry. In recent years, there have been sporadic releases, runaway
reactions, fires, and thermal explosion accidents incurred by styrene and its derivatives worldwide. The purpose of this study
was to estimate the impact of styrene and its derivatives of α-methylstyrene (AMS) and trans-β-methylstyrene (TBMS) contacting with benzaldehyde. Experiments were carried out to evaluate the thermokinetic parameters
estimated by differential scanning calorimetry (DSC) and thermal activity monitor III (TAM III). TAM III was used to determine
the fundamental thermokinetics under various isothermal temperatures, 80, 90 and 100°C. This autocatalytic reaction was demonstrated
in thermal curves. After styrene was contacted with benzaldehyde, the exothermic onset temperature (T
0) and the total heat of reaction (Q
total) were altered by DSC tests. When benzaldehyde is mixed with AMS and TBMS, the reaction time will be shorter but the enthalpy
reduced, as revealed by TAM III tests.
As AMS and TBMS, respectively, were contacted with benzaldehyde, both exothermic phenomena were changed during the reaction
excursion. According to the results of this research, an operator should dictate the oxygen concentration in order to avoid
any potential hazards during handling and transportation. 相似文献
992.
C. -W. Chang Y. -C. Chou J. -M. Tseng M. -Y. Liu C. -M. Shu 《Journal of Thermal Analysis and Calorimetry》2009,95(2):639-643
Many concerns over unsafe or unknown properties of multi-walled carbon nanotubes (MWNTs) have been raised. The thermal characteristics
regarding stability would represent potential hazards during the production or utilization stage and could be determined by
calorimetric tests for various thermokinetic parameters. Differential scanning calorimetry (DSC) was employed to evaluate
the thermokinetic parameters for MWNTs at various compositions.
Thermoanalytical curves showed that the average heat of decomposition (ΔH
d) of the MWNTs samples in a manufacturing process was about 31,723 J g−1, by identifying them as an inherently hazardous material. In this study, significant thermal analysis appeared in the presence
of sulfuric acid (H2SO4). From the DSC experiments, the purification process of MWNTs could induce an unexpected reaction in the condition of batch
addition with reactants of H2SO4. The results can be applied for designing emergency relief system and emergency rescue strategies during a perturbed situation
or accident. 相似文献
993.
Yun‐Peng Diao Kun Li Shan‐Shan Huang Xiao‐Hong Shu Ke‐Xin Liu Xu‐Ming Deng 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(2):m82-m85
In the mixed‐ligand metal–organic polymeric compound poly[[μ2‐1,4‐bis(imidazol‐1‐yl)benzene](μ2‐terephthalato)dizinc(II)], [Zn2(C8H4O4)2(C12H10N4)]n or [Zn2(bdc)2(bib)]n [H2bdc is terephthalic acid and bib is 1,4‐bis(imidazol‐1‐yl)benzene], the asymmetric unit contains one ZnII ion, with two half bdc anions and one half bib molecule lying around inversion centers. The ZnII ion is in a slightly distorted tetrahedral environment, coordinated by three carboxylate O atoms from three different bdc anions and by one bib N atom. The crystal structure is constructed from the secondary building unit (SBU) [Zn2(CO2)2N2O2], in which the two metal centers are held together by two bdc linkers with bis(syn,syn‐bridging bidentate) bonding modes. The SBU is connected by bdc bridges to form a two‐dimensional grid‐like (4,4)‐layer, which is further pillared by the bib ligand. Topologically, the dinuclear SBU can be considered to be a six‐connected node, and the extended structure exhibits an elongated primitive approximately cubic framework. The three‐dimensional framework possesses a large cavity with dimensions of approximately 10 × 13 × 17 Å in cross‐section. The potential porosity is filled with mutual interpenetration of two identical equivalent frameworks, generating a novel threefold interpenetrating network with an α‐polonium topology [Abrahams, Hoskins, Robson & Slizys (2002). CrystEngComm, 4 , 478–482]. 相似文献
994.
Gabriel Wittum 《计算数学(英文版)》2009,(5):563-572
In this paper, we obtain optimal error estimates in both L^2-norm and H(curl)-norm for the Nedelec edge finite element approximation of the time-harmonic Maxwell's equations on a general Lipschitz domain discretized on quasi-uniform meshes. One key to our proof is to transform the L^2 error estimates into the L^2 estimate of a discrete divergence-free function which belongs to the edge finite element spaces, and then use the approximation of the discrete divergence-free function by the continuous divergence-free function and a duality argument for the continuous divergence-free function. For Nedelec's second type elements, we present an optimal convergence estimate which improves the best results available in the literature. 相似文献
995.
Let \({\varphi: \mathbb{P}^N_K\to\mathbb{P}^N_K}\) be a morphism of degree d ≥ 2 defined over a field K that is algebraically closed field and complete with respect to a nonarchimedean absolute value. We prove that a modified Green function \({\hat{g}_\varphi}\) associated to \({\varphi}\) is Hölder continuous on \({\mathbb{P}^N(K)}\) and that the Fatou set \({\mathcal{F}(\varphi)}\) of \({\varphi}\) is equal to the set of points at which \({\hat{g}_\Phi}\) is locally constant. Further, \({\hat{g}_\varphi}\) vanishes precisely on the set of points P such that \({\varphi}\) has good reduction at every point in the forward orbit \({\mathcal{O}_\varphi(P)}\) of P. We also prove that the iterates of \({\varphi}\) are locally uniformly Lipschitz on \({\mathcal{F}(\varphi)}\) . 相似文献
996.
997.
研究了一类时滞离散神经网络指数稳定及鲁棒稳定问题.结合线性矩阵不等式技术,构造了一个新的广义李亚普诺夫函数,得到了新的指数稳定条件.数值算例表明与以往文献中的结果相比,新准则具有较弱的保守性. 相似文献
998.
In this paper, we discuss the G-decomposition of λKv into 6-circuits with two chords. We construct some holey G-designs using sharply 2-transitive group, and present the recursive structure by PBD. We also give a unified method to construct G-designs when the index equals the edge number of the discussed graph. Finally, the existence of G-GDλ(v) is given. 相似文献
999.
A new fixed point theorem and the selection property for upper semi-continuous set-valued mappings in abstract convexity space are established. As their applications the existence of Nash equilibrium for n-person non-cooperative generalized games is proved. 相似文献
1000.
Abe M Hattori M Takegami A Masuyama A Hayashi T Seki S Tagawa S 《Journal of the American Chemical Society》2006,128(24):8008-8014
A detailed study of the regioselectivity of 1,2-oxygen migration was conducted using the unsymmetrically substituted singlet 2,2-dialkoxy-1,3-diarylcyclopentane-1,3-diyls 5. The alkoxy group selectively migrates to the electron-donating p-methoxyphenyl-substituted carbon. The regioselective migration of oxygen clearly indicates a hyperconjugative resonance structure, that is, zwitterionic characteristics, in singlet 2,2-dialkoxy-1,3-diyls. This represents the first attempt to experimentally probe the contribution of hyperconjugation to stabilizing the singlet state. 相似文献