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The concentration of Fe(II) ion is determined by chelation with 2-nitroso-5-diehtylaminophenol and liquid-liquid extraction into chloroform. Light absorption at 780 nm is measured with a thermal lens spectrophotometer equipped with a semiconductor laser as a light source. The enhancement factor achieved experimentally is 47. The detection limit of Fe(II) ion is 8.1 × 10?9 M, which is 3–4 times better than that obtained by conventional absorption spectrometry, and is governed by the background signal originating from Fe(II) impurity in the reagent. 相似文献
94.
The ion transfer of creatinine (CRE) at a polarized nitrobenzene (NB)/water (W) interface has been studied. When the pH of the W phase is in the range of 1.2 to 4.0, a well‐defined voltammetric wave is observed for a simple transfer of CRE+ (protonated form) at the NB/W interface. This transfer reaction has been applied to develop an amperometric method for the determination of CRE in urine. In this system, the NB/W interface is covered with a dialysis membrane to prevent possible interference from urine proteins. The concentration of CRE in a urine control has successfully been determined. 相似文献
95.
A new partitioning scheme for the total energy of molecules is presented. In the scheme, the Hartree-Fock total energy of a molecular system is represented as the sum of one- and two-center terms exactly. The present method provides physically reasonable behavior for a wide range of interactions, and intermolecular interaction is treated equivalently with intramolecular interaction. The method is applied to analysis on the inter- and intramolecular interactions of molecular complexes both in gas phase and in aqueous solution. The results strongly indicate that the present method is a powerful tool to understand not only the bonding nature of molecules but also interaction between molecules. 相似文献
96.
SN1‐SN2 and SN2‐SN3 mechanistic changes revealed by transition states of the hydrolyses of benzyl chlorides and benzenesulfonyl chlorides 下载免费PDF全文
Shinichi Yamabe Guixiang Zeng Wei Guan Shigeyoshi Sakaki 《Journal of computational chemistry》2014,35(15):1140-1148
Hydrolysis reactions of benzyl chlorides and benzenesulfonyl chlorides were theoretically investigated with the density functional theory method, where the water molecules are explicitly considered. For the hydrolysis of benzyl chlorides (para‐Z? C6H4? CH2? Cl), the number of water molecules (n) slightly influences the transition‐state (TS) structure. However, the para‐substituent (Z) of the phenyl group significantly changes the reaction process from the stepwise (SN1) to the concerted (SN2) pathway when it changes from the typical electron‐donating group (EDG) to the typical electron‐withdrawing one (EWG). The EDG stabilizes the carbocation (MeO? C6H4? CH2+), which in turn makes the SN1 mechanism more favorable and vice versa. For the hydrolysis of benzenesulfonyl chlorides (para‐Z? C6H4? SO2? Cl), both the Z group and n influence the TS structure. For the combination of the large n value (n > 9) and EDG, the SN2 mechanism was preferred. Conversely, for the combination of the small n value and EWG, the SN3 one was more favorable. © 2014 Wiley Periodicals, Inc. 相似文献
97.
Naoki Kondo Shigeki Kobayashi Hiroyuki Sakaki 《Physica E: Low-dimensional Systems and Nanostructures》2006,32(1-2):49
The self-organized crystal growth of semiconductor quantum rings has opened a new possibility to study and exploit optical transitions between ring-shaped quantum states. In such states, orbital angular momenta of particle envelope functions are well-defined. We investigate theoretically the intraband interlevel transitions between such states and examine the possibility of electrical multipole radiations (EMRs). Selections rules due to envelope function quantum numbers are deduced. To enhance the EMR efficiency, we propose a novel coupled dot–ring structure, by which the lowest allowed EMR can be selected and manipulated, allowing the efficient radiation of multipole photons. 相似文献
98.
Kazuhide Ichikawa Ayumu Wagatsuma Yusaku I. Kurokawa Shigeyoshi Sakaki Akitomo Tachibana 《Theoretical chemistry accounts》2011,130(2-3):237-250
We study the electronic structure of two types of transition metal complexes, the inverted-sandwich-type and open-lantern-type, by the electronic stress tensor. In particular, the bond order $b_\varepsilon$ measured by the energy density which is defined from the electronic stress tensor is studied and compared with the conventional MO-based bond order. We also examine the patterns found in the largest eigenvalue of the stress tensor and corresponding eigenvector field, the ??spindle structure?? and ??pseudo-spindle structure??. As for the inverted-sandwich-type complex, our bond order $b_\varepsilon$ calculation shows that relative strength of the metal-benzene bond among V, Cr, and Mn complexes is V?>?Cr?>?Mn, which is consistent with the MO-based bond order. As for the open-lantern-type complex, we find that our energy density-based bond order can properly describe the relative strength of Cr?CCr and Mo?CMo bonds by the surface integration of the energy density over the ??Lagrange surface?? which can take into account the spatial extent of the orbitals. 相似文献
99.
We explored the interactions of gas molecules such as H2, CH4, C2H4, C2H6, CO2, and CS2 sandwiched by two pyrazine (Pz) molecules, which were employed as a model of organic linker in the Hofmann-type metal?Corganic framework (MOF). The MP2.5/aug-cc-pVTZ method was employed here, because this method presents almost the same binding energy as that calculated by the CCSD(T)/aug-cc-pVDZ with MP2.5-evaluated basis set extension effects to aug-cc-pVTZ basis set. The binding energy of the gas molecule increases in the order H2?<?CH4?<?CO2?<?C2H4????C2H6?<?CS2. The energy decomposition analysis of the interaction energy indicates that the electrostatic term presents the largest contribution to the interaction energy at the Hartree?CFock level. However, the dispersion interaction provides dominant contribution to the total binding energy at correlated level. We newly found a linear correlation between the z-component of polarizability of gas molecules and dispersion energy, where the z-axis was taken to be perpendicular to two Pz rings. These results are useful for understanding and predicting the binding energy of the gas molecule with the organic linkers of MOF. 相似文献
100.
Keisuke Umakoshi Prof. Dr. Keizo Saito Yasuhiro Arikawa Dr. Masayoshi Onishi Prof. Shoji Ishizaka Dr. Noboru Kitamura Prof. Dr. Yoshihide Nakao Dr. Shigeyoshi Sakaki Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(17):4238-4242
Swap the coins! The Pt2Au2, Pt2Au2Cu2, and Pt2Au2Ag2 complexes of 3,5‐dimethylpyrazolate exhibit yellow‐green, orange, and sky‐blue luminescence, respectively (see figure). The emission energies of Pt2Au2M2 complexes can be controlled by the change of the third coinage metal ions M. The Pt2Au2M2 complexes take the cis configuration with respect to the Au2M2 plane.