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991.
Chang Ho Lee Seung Hoon Ryu Se Young Oh 《Journal of Polymer Science.Polymer Physics》2003,41(21):2733-2743
We have synthesized a novel carrier‐transporting copolymer and a nonconjugated light‐emitting polymer. The carrier‐transporting copolymer has a triphenylamine moiety as a hole‐transporting unit and a triazine moiety as an electron‐transporting unit, both of which are located in the polymer side chain. The nonconjugated light‐emitting polymer has a perylene moiety, which acts as an emitting unit in the polymer side chain. These polymers are very soluble in most organic solvents, such as monochlorobenzene, tetrahydrofuran, chloroform, and benzene. A single‐layered electroluminescent device consisting of ITO/copolymer and emitting‐material 4‐(dicyanomethylene)‐2‐methyl‐6‐(4‐dimethylaminostyryl)‐4H‐pyran (DCM) or light‐emitting polymer)/Al mixtures exhibits maximum external quantum efficiency when the concentration of the emitting material is 30 wt %. The device emits red or blue light according to the emitting material. When CsF is used as the electron‐injecting material, the drive voltage decreases drastically to 7 V, and the highest quantum efficiency is 0.5%. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2733–2743, 2003 相似文献
992.
V. S. Kolosnitsyn E. V. Karaseva D. Y. Seung M. D. Cho 《Russian Journal of Electrochemistry》2002,38(12):1314-1318
The cycling of a sulfur electrode is studied in 1 M LiCF3SO3 solutions in sulfolane mixtures with ethers 1,2-dimethoxyethane, dioxolane, and tetrahydrofuran. The results suggest that the electrochemical behavior of sulfur is defined by the forms of existence of lithium polysulfides in the electrolyte. 相似文献
993.
Enhanced Pseudocapacitance in Multicomponent Transition‐Metal Oxides by Local Distortion of Oxygen Octahedra 下载免费PDF全文
Hyeon Jeong Lee Ji Hoon Lee Prof. Sung‐Yoon Chung Prof. Jang Wook Choi 《Angewandte Chemie (International ed. in English)》2016,55(12):3958-3962
Anomalously high pseudocapacitance of a metal oxide was observed when Ni, Co, and Mn were mixed in a solid solution. Analysis by X‐ray absorption near‐edge spectroscopy (XANES) identified a wider redox swing of Ni as the origin of the enlarged pseudocapacitance. Ab initio DFT calculations revealed that aliovalent species resulting from the copresence of multiple transition metals can generate permanent local distortions of [NiO6] octahedra. As this type of distortion breaks the degenerate eg level of Ni2+, the Jahn–Teller lattice instability necessary for the Ni2+/3+ redox flip can be effectively diminished during charge–discharge, thus resulting in the significantly increased capacitance. Our findings highlight the importance of understanding structure–property correlation related to local structural distortions in improving the performance of pseudocapacitors. 相似文献
994.
Elemental‐Sulfur‐Mediated Facile Synthesis of a Covalent Triazine Framework for High‐Performance Lithium–Sulfur Batteries 下载免费PDF全文
Dr. Siddulu Naidu Talapaneni Tae Hoon Hwang Sang Hyun Je Dr. Onur Buyukcakir Prof. Jang Wook Choi Prof. Ali Coskun 《Angewandte Chemie (International ed. in English)》2016,55(9):3106-3111
A covalent triazine framework (CTF) with embedded polymeric sulfur and a high sulfur content of 62 wt % was synthesized under catalyst‐ and solvent‐free reaction conditions from 1,4‐dicyanobenzene and elemental sulfur. Our synthetic approach introduces a new way of preparing CTFs under environmentally benign conditions by the direct utilization of elemental sulfur. The homogeneous sulfur distribution is due to the in situ formation of the framework structure, and chemical sulfur impregnation within the micropores of CTF effectively suppresses the dissolution of polysulfides into the electrolyte. Furthermore, the triazine framework facilitates electron and ion transport, which leads to a high‐performance lithium–sulfur battery. 相似文献
995.
Corrigendum: Tetrazole Photoclick Chemistry: Reinvestigating Its Suitability as a Bioorthogonal Reaction and Potential Applications 下载免费PDF全文
996.
The effect of uniform external electric field on the interactions between small aromatic compounds and an argon atom is investigated using post‐HF (MP2, SCS‐MP2, and CCSD(T)) and density functional (PBE0‐D3, PBE0‐TS, and vdW‐DF2) methods. The electric field effect is quantified by the difference of interaction energy calculated in the presence and absence of the electric field. All the post‐HF methods describe electric field effects accurately although the interaction energy itself is overestimated by MP2. The electric field effect is explained by classical electrostatic models, where the permanent dipole moment from mutual polarization mainly determines its sign. The size of π‐conjugated system does not have significant effect on the electric field dependence. We found out that PBE0‐based methods give reasonable interaction energies and electric field response in every case, while vdW‐DF2 sometimes shows spurious artifact owing to its sensitivity toward the real space electron density. © 2015 Wiley Periodicals, Inc. 相似文献
997.
Mei Itabashi Chigen Tsukamoto Ayaka Kurosaka Panneerselvam Krishnamurthy Tai-Sun Shin Seung Hwan Yang 《液相色谱法及相关技术杂志》2016,39(14):640-646
New saponin components, Sg-6 saponins, have been recently reported from the seeds of wild soybean (Glycine soja) which may have specific health benefits. To evaluate the possible health benefits, a large amount of Sg-6 saponins are needed, but general group A acetyl saponins and new Sg-6 saponins are eluted in overlapping peaks by ordinal preparative high-performance liquid chromatography and/or open column methods. A new method is proposed in this report. This method includes (1) deacetylation of group A acetyl saponins in alkali condition with KOH, (2) precipitation of Sg-6 saponins in acid condition with HCl, (3) recovery of Sg-6 saponins with aqueous methanol from the precipitate, and (4) elution of Sg-6 saponins by preparative reverse-phase open column. With this method, from 450?g of wild soybean whole seed powder, about 1?g of Sg-6 saponins (mixture of six components) was clearly separated from other saponins with 61% recovery. 相似文献
998.
Yeong-Soon Gal Sung-Ho Jin Won-Chul Lee Jong-Wook Park Kwon Taek Lim Won Seok Lyoo Sang Youl Kim 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(9):1447-1450
The electrooptical and electrochemical properties of a self-dopable ionic conjugated polyacetylene, poly(2-ethynylpyridinium-N-benzoylsulfonate)
(PEPBS), were studied. The photoluminescence spectra of the polymer showed that the photoluminescence peak was located at
545 nm corresponding to the photon energy of 2.27 eV. The cyclic voltammograms of the polymer exhibited reversible electrochemical
behaviors between the doped and undoped peaks. It was found from the dependence of the oxidation current density of the polymer
on scan rate that the kinetics of the redox process was diffusion-controlled. The electrical conductivity (σ) of undoped PEPBS
was 5.7 × 10−9 S/cm.
The text was submitted by the authors in English. 相似文献
999.
New chromogenic diazophenylcalix[4]arenes 1 and 2 were synthesized in cone conformation. Compound 1 with the ortho-carboxyl groups in CH3CN solution preferentially binds with alkaline earth and transition metal ions, whereas no significant changes in absorption spectra are observed in the presence of alkali metal ions. While 2 with the ortho-ester groups shows selective complexation properties towards transition metal ions over alkali and alkaline earth metal ions. The detection of metal ions gives rise to bathochromic shifts in the absorption spectra (from orange/yellow to red), which is clearly visible even to the naked eye. According to the selective color changes using both receptors upon cation complexation, one can set up a qualitative analytical routine to screen alkali, alkaline earth, and transition metal ions. 相似文献
1000.
Sang Wook Kang Dong Hoon Lee Jong Hyuk Park Kookheon Char Jong Hak Kim Jongok Won Yong Soo Kang 《Journal of membrane science》2008
The effect of ionic liquids on the formation of a partial positive charge on the surface of silver nanoparticle and its subsequent effect on facilitated olefin transport were investigated. Three different ionic liquids of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM+BF4−), 1-butyl-3-methylimidazolium triflate (BMIM+Tf−), and 1-butyl-3-methylimidazolium nitrate (BMIM+NO3−) were employed to control the positive charge density of the surface of silver nanoparticles. The positive charge density of the silver nanoparticles, as characterized by the binding energy of the silver atom, was in the following order: BMIM+BF4−/Ag ? BMIM+Tf−/Ag > BMIM+NO3−/Ag. This order was consistent with the tendency of ionic liquids to form free ions. The best separation performance for the propylene/propane mixtures was a mixed gas selectivity of 17 and a permeance of 7 GPU through a composite membrane consisting of BMIM+BF4−/Ag. A better separation performance for olefin/paraffin mixtures was observed with a higher positive charge density of the silver nanoparticles. It was therefore concluded that facilitated olefin transport was a direct consequence of the surface positive charge of the silver nanoparticles induced by ionic liquids. 相似文献