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We presented the optical properties of a novel block copolymer containing chromophores, 2,5‐dimethoxy‐1,4‐di(α‐(2‐naphthalene vinylene)benzene (MDNVB) and spacers, tri(ethylene oxide) (TEO). The intrachain and interchain excitations due to the molecular aggregation are responsible for the significant bathochromic shift in the photoluminescence (PL) spectrum when going from the solution to the thin film. With a certain content of the polymer electrolyte, blue–green light‐emitting electrochemical cell based on this block copolymer was demonstrated with the turn‐on voltage of 2.5 V, the maximum electroluminescence (EL) efficiency of 1.2 cd/A, and the d.c. response time of less than 5 sec, indicating strongly that an improved morphology of the active layer is formed because of the effective TEO‐PEO interaction. Lowering the content of the polymer electrolyte results in a higher turn‐on voltage and smaller injection current; increasing the content leads to a considerable microscopic leaking current and lower EL efficiency of the device. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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聚呲咯循环伏安特性的光谱电化学分析 总被引:1,自引:0,他引:1
用循环伏安法研究导电聚吡咯膜的电化学特性时,人们发现有很大的充电电流的影响,这给循环伏安图的峰电流和峰电位带来一定的误差。在水溶液中进行研究时,H~+、OH~-和H_2O参与的付反应使得正确分析循环伏安图更为困难。为了排除达些干扰,本文根据聚吡咯可见-近红外区光吸收随扫描电位变化的特点,提出了一种获取循环伏安曲线的光谱电化学方法,并用这种方法研究了以Cl~-为对阴离子的导电聚吡咯PPy(Cl)在酸性水溶液中的循环伏安特性。 相似文献
225.
A study on the electrooxidative polymerization of pyrrole onto polyurethane-coated platinum electrodes and the electrochemical properties of the composite polyurethane/polypyrrole films (PU/PPy) as-prepared is presented. It is found that polypyrrole grows layer by layer from the polyurethane/platinum interface through the polyurethane matrix, and ca. 20 wt.% of polypyrrole will fill up the matrix. Cyclic voltemmograms show that the composite films are porous, and the reduction-reoxidation (redox) rate of the composite films is limited by the diffusion of counteranions through the films. Larger anion size leads to slower diffusion process. The composite films can also act as modified electrodes. 相似文献
226.
Lijun Huo Chang He Minfang Han Erjun Zhou Yongfang Li 《Journal of polymer science. Part A, Polymer chemistry》2007,45(17):3861-3871
A series of alternating copolymers of electron‐rich arylamine and electron‐deficient 2,1,3‐benzothiadiazole (BT), PV‐BT, DP‐BT, and TP‐BT, were synthesized by Heck coupling reaction. UV–vis absorption and fluorescence spectra show that the copolymerization of electron‐rich diphenylamine (DP), triphenylamine (TP), MEH‐PV (PV), and electron‐deficient BT results in low‐bandgap conjugated polymers. Within the three copolymers of PV‐BT, DP‐BT, and TP‐BT, TP‐BT possesses the highest hole mobility of 4.68 × 10? 5 cm2/V, as determined from the space charge limited current (SCLC) model. The bulk heterojunction‐typed polymer solar cells (PSCs) were fabricated with the blend of the copolymers and PCBM as the photosensitive layer. The power conversion efficiencies (PCE) of the PSCs based on PV‐BT, DP‐BT, and TP‐BT reached 0.26%, 0.39%, and 0.52%, respectively, under the illumination of AM 1.5, 100 mW/cm2. The results indicate that TP‐BT is a promising photovoltaic polymer for PSCs. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3861–3871, 2007 相似文献
227.
Meixiu Wan Weiping Wu Guangyi Sang Yingping Zou Yunqi Liu Yongfang Li 《Journal of polymer science. Part A, Polymer chemistry》2009,47(16):4028-4036
A novel conjugated polymer, poly(thienylene‐vinylene‐thienylene) with cyano substituent ( CN‐PTVT ) was synthesized via Stille coupling for the application in air stable field‐effect transistor and polymer solar cell. The polymer was characterized by 1H NMR, elemental analysis, UV‐vis absorption and photoluminescence spectroscopy, TGA, cyclic voltammetry and XRD analysis. CN‐PTVT exhibits a good thermal stability with 5% weight loss at 306 °C. The FET hole mobility of the polymer reached 5.9 × 10?3 cm2 V?1 s?1 with Ion/Ioff ratio of 4.9 × 104, which is one of the highest performance among the air‐stable amorphous polymers. The polymer solar cell based on CN‐PTVT as donor and PCBM as acceptor shows a relatively high open‐circuit voltage of 0.82 V and a power conversion efficiency of 0.3% under the illumination of AM1.5, 100 mW/cm2. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4028–4036, 2009 相似文献
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229.
Zhao Fuwen He Dan Xin Jingming Dai Shuixing Xue Han Jiang Li Wei Zhixiang Ma Wei Zhan Xiaowei Li Yongfang Wang Chunru 《中国科学:化学(英文版)》2019,62(6):790-796
In this work, four fused ring electron acceptors(FREAs), 2F-C5, 2F-C6, 2F-C8 and 2F-C10, are developed to investigate the effect of side-chain size on the molecular properties and photovoltaic performance of FREA systematically. The elongation of side-chains in the FREAs not only improves their solubility in the processing solvent, but also enhances their miscibility with the donor PBDB-T. It helps the FREA diffuse into the donor PBDB-T during film-formation, thus leading to the decrease in domain size and domain purity from PBDB-T:2F-C5 to PBDB-T:2F-C10 blend films in sequence. The smaller domain size affords more D/A interfaces to benefit exciton dissociation and inhibit monomolecular recombination. However, severe bimolecular recombination occurs when the domain purity decreases to a critical point. Due to the dual function of the increment of side-chain length, both short-circuit current density(J_(SC)) and fill factor(FF) of devices exhibit an evolution of first increasing then decreasing from 2F-C5, 2F-C6, 2F-C8 to 2F-C10 based OSCs. The PBDB-T:2F-C8 based OSCs get a fine balance in morphology with moderate domain size as well as high domain purity simultaneously for the least charge carrier recombination, thus achieving the highest power conversion efficiency of 12.28% with the best J_(SC)(21.27 mA cm~(-2)) and FF(71.96%). 相似文献
230.
In this note, the mixed unsteady stagnation-point boundary layer over a vertical plate with mass transfer in a fluid-saturated porous medium is revisited. Closed-form analytical solutions are found and presented for a special value of the flow unsteadiness parameter. Multiple solution branches are obtained for certain controlling parameters. These solutions might offer more insights into the mixed convection flow characteristics compared with the numerical solutions. 相似文献