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881.
Toshiyuki Fujii Akihiro Uehara Yoshihiro Kitatsuji Hajimu Yamana 《Journal of Radioanalytical and Nuclear Chemistry》2014,301(1):293-296
Coordination circumstance of neptunyl ion in concentrated CaCl2 solutions was analyzed by Raman spectrometry. Besides the symmetric stretch (ν1) mode of NpO2 + and NpO2 2+, the asymmetric stretch (ν3) mode of NpO2 + was found. The Raman intensity of the ν3 mode increased with the concentration of CaCl2 in the system. This would be attributable to the cation–cation interaction between Np(V) and Ca(II). 相似文献
882.
Yoshinori Okuno Shigeki Isomura Akihiro Nishibayashi Aiko Hosoi Kei Fukuyama Masashi Ohba 《合成通讯》2014,44(19):2854-2860
A convenient and efficient esterification method that used a modified Yamaguchi reagent (2,4,6-trichlorobenzoyl chloride–4-dimethylaminopyridine) and avoided use not only of intractable acid chloride but also of acid anhydrides was proposed. The reaction mechanism was described by Fourier transform infrared spectroscopy and supported by a density functional theory calculation. 相似文献
883.
Halogen‐ and Hydrogen‐Bonded Salts and Co‐crystals Formed from 4‐Halo‐2,3,5,6‐tetrafluorophenol and Cyclic Secondary and Tertiary Amines: Orthogonal and Non‐orthogonal Halogen and Hydrogen Bonding,and Synthetic Analogues of Halogen‐Bonded Biological Systems 下载免费PDF全文
Akihiro Takemura Linda J. McAllister Sam Hart Natalie E. Pridmore Dr. Peter B. Karadakov Dr. Adrian C. Whitwood Prof. Dr. Duncan W. Bruce 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6721-6732
Co‐crystallisation of, in particular, 4‐iodotetrafluorophenol with a series of secondary and tertiary cyclic amines results in deprotonation of the phenol and formation of the corresponding ammonium phenate. Careful examination of the X‐ray single‐crystal structures shows that the phenate anion develops a C?O double bond and that the C?C bond lengths in the ring suggest a Meissenheimer‐like delocalisation. This delocalisation is supported by the geometry of the phenate anion optimised at the MP2(Full) level of theory within the aug‐cc‐pVDZ basis (aug‐cc‐pVDZ‐PP on I) and by natural bond orbital (NBO) analyses. With sp2 hybridisation at the phenate oxygen atom, there is strong preference for the formation of two non‐covalent interactions with the oxygen sp2 lone pairs and, in the case of secondary amines, this occurs through hydrogen bonding to the ammonium hydrogen atoms. However, where tertiary amines are concerned, there are insufficient hydrogen atoms available and so an electrophilic iodine atom from a neighbouring 4‐iodotetrafluorophenate group forms an I???O halogen bond to give the second interaction. However, in some co‐crystals with secondary amines, it is also found that in addition to the two hydrogen bonds forming with the phenate oxygen sp2 lone pairs, there is an additional intermolecular I???O halogen bond in which the electrophilic iodine atom interacts with the C?O π‐system. All attempts to reproduce this behaviour with 4‐bromotetrafluorophenol were unsuccessful. These structural motifs are significant as they reproduce extremely well, in low‐molar‐mass synthetic systems, motifs found by Ho and co‐workers when examining halogen‐bonding interactions in biological systems. The analogy is cemented through the structures of co‐crystals of 1,4‐diiodotetrafluorobenzene with acetamide and with N‐methylbenzamide, which, as designed models, demonstrate the orthogonality of hydrogen and halogen bonding proposed in Ho’s biological study. 相似文献
884.
Dr. Satoshi Takeya Dr. Hiroshi Fujihisa Dr. Akihiro Hachikubo Dr. Hirotoshi Sakagami Dr. Yoshito Gotoh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(51):17207-17213
To understand host–guest interactions of hydrocarbon clathrate hydrates, we investigated the crystal structure of simple and binary clathrate hydrates including butane (n‐C4H10 or iso‐C4H10) as the guest. Powder X‐ray diffraction (PXRD) analysis using the information on the conformation of C4H10 molecules obtained by molecular dynamics (MD) simulations was performed. It was shown that the guest n‐C4H10 molecule tends to change to the gauche conformation within host water cages. Any distortion of the large 51264 cage and empty 512 cage for the simple iso‐C4H10 hydrate was not detected, and it was revealed that dynamic disorder of iso‐C4H10 and gauche‐nC4H10 were spherically extended within the large 51264 cages. It was indicated that structural isomers of hydrocarbon molecules with different van der Waals diameters are enclathrated within water cages in the same way owing to conformational change and dynamic disorder of the molecules. Furthermore, these results show that the method reported herein is applicable to structure analysis of other host–guest materials including guest molecules that could change molecular conformations. 相似文献
885.
Bissan Ghaddar Joe Naoum-Sawaya Akihiro Kishimoto Nicole Taheri Bradley Eck 《European Journal of Operational Research》2015
Dynamic pricing has become a common form of electricity tariff, where the price of electricity varies in real time based on the realized electricity supply and demand. Hence, optimizing industrial operations to benefit from periods with low electricity prices is vital to maximizing the benefits of dynamic pricing. In the case of water networks, energy consumed by pumping is a substantial cost for water utilities, and optimizing pump schedules to accommodate for the changing price of energy while ensuring a continuous supply of water is essential. In this paper, a Mixed-Integer Non-linear Programming (MINLP) formulation of the optimal pump scheduling problem is presented. Due to the non-linearities, the typical size of water networks, and the discretization of the planning horizon, the problem is not solvable within reasonable time using standard optimization software. We present a Lagrangian decomposition approach that exploits the structure of the problem leading to smaller problems that are solved independently. The Lagrangian decomposition is coupled with a simulation-based, improved limited discrepancy search algorithm that is capable of finding high quality feasible solutions. The proposed approach finds solutions with guaranteed upper and lower bounds. These solutions are compared to those found by a mixed-integer linear programming approach, which uses a piecewise-linearization of the non-linear constraints to find a global optimal solution of the relaxation. Numerical testing is conducted on two real water networks and the results illustrate the significant costs savings due to optimizing pump schedules. 相似文献
886.
Benini Francesco Eager Richard Hori Kentaro Tachikawa Yuji 《Communications in Mathematical Physics》2015,337(3):1241-1253
We consider the spectrum of discrete Schrödinger operators with Sturmian potentials and show that for sufficiently large coupling, its Hausdorff dimension and its upper box counting dimension are the same for Lebesgue almost every value of the frequency. 相似文献
887.
Takeshi Uda Toshiyuki Fujii Yasuhiko Iwadate Akihiro Uehara Hajimu Yamana 《无机化学与普通化学杂志》2013,639(5):765-769
Raman spectra of rare earth (REE: rare earth elements) trichloride (REE = Y, La, Ce, Pr, Sm, Gd, Dy, or Yb) dissolved in alkali chloride eutectic melts (LiCl‐KCl, LiCl‐RbCl, and LiCl‐CsCl) were measured at 793 K. The spectra showed polarized peaks centered around 240–270 cm–1, which were identified as the totally symmetric stretching vibration (ν1) of the octahedral REECl63–. The ν1 frequency increased with the polarizing power of the trivalent REE ions. The change in the ν1 frequency was found to be larger for lighter lanthanides. This was attributable to the distortion of the Oh symmetry of REECl63–. 相似文献
888.
Poly(L‐lactic acid) (PLLA) was mixed with a few weight percent of magnesium or calcium hydrogen phosphate to improve the thermal property. Calcium hydrogen phosphate as an additive to PLLA was found to be more effective in increasing the glass transition point (Tg) than magnesium hydrogen phosphate, which was investigated by the differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Studies on the coordination structure for the polymer complex (ca‐(plla)) confirmed by infrared (IR) spectroscopy and extended X‐ray absorption fine structure (EXAFS) indicated that calcium ion radius would be suitable for the coordination with carbonyl groups of polymer chains. 相似文献
889.
Takumi Nakanishi Yuta Hori Shuqi Wu Hiroyasu Sato Atsushi Okazawa Norimichi Kojima Yusuke Horie Hajime Okajima Akira Sakamoto Yoshihito Shiota Kazunari Yoshizawa Osamu Sato 《Angewandte Chemie (International ed. in English)》2020,59(35):14781-14787
A proton–electron coupling system, exhibiting unique bistability or multistability of the protonated state, is an attractive target for developing new switchable materials based on proton dynamics. Herein, we present an iron(II) hydrazone crystalline compound, which displays the stepwise transition and bistability of proton transfer at the crystal level. These phenomena are realized through the coupling with spin transition. Although the multi‐step transition with hysteresis has been observed in various systems, the corresponding behavior of proton transfer has not been reported in crystalline systems; thus, the described iron(II) complex is the first example. Furthermore, because proton transfer occurs only in one of the two ligands and π electrons redistribute in it, the dipole moment of the iron(II) complexes changes with the proton transfer, wherein the total dipole moment in the crystal was canceled out owing to the antiferroelectric‐like arrangement. 相似文献
890.
Toshihide Taniguchi Mitsutaka Imoto Motonori Takeda Takeo Nakai Masatoshi Mihara Toshiyuki Iwai Takatoshi Ito Takumi Mizuno Akihiro Nomoto Akiya Ogawa 《Heteroatom Chemistry》2015,26(6):411-416
A new method for the hydrolysis of diazonium salts, without the formation of tar, was developed. A two‐phase system consisting of cyclopentyl methyl ether (CPME) and water is very effective for the hydrolysis of diazonium salts. Using this solvent system, the diazonium salt prepared from 3‐(4‐nitrophenoxy)aniline gave 3‐(4‐nitrophenoxy)phenol in high yield (96%) within 20 min. The synthesized phenol is an industrially important raw material in polymer syntheses. Furthermore, the use of the present two‐phase system of CPME and water successfully brought about the efficient conversions of several m‐substituted anilines into the corresponding m‐substituted phenols. This is the first example of hydrolysis of diazonium salts using the two‐phase system (CPME and water). 相似文献