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排序方式: 共有124条查询结果,搜索用时 31 毫秒
71.
An improved, efficient preparation of 2‐(halomethyl)allyl carboxylates starting from diethyl bis(hydroxymethyl)malonate and hydrobromic acid is reported. The allylic halogen of 2‐(chloromethyl)acrylate and 2‐(bromomethyl)acrylate are readily exchanged during esterification. 相似文献
72.
Han‐Shiang Huag Shiu‐Huey Chou Trong‐Ming Don Wei‐Chi Lai Liao‐Ping Cheng 《先进技术聚合物》2009,20(12):1082-1090
Microporous membranes of a biodegradable polymer, poly(hydroxybutyric acid) (PHB), were prepared by a phase‐inversion process and their cell compatibility was evaluated in vitro. A ternary system, ethanol/chloroform/PHB, was employed to prepare the membranes, wherein ethanol and chloroform were served as the nonsolvent and solvent for PHB, respectively. In the phase‐inversion process, the polymer dissolution temperature was varied from 80 to 120°C to yield membranes with specific morphologies, such as globular particles, porous channels, etc. Moreover, cell viability was examined on the formed membranes. Two cell lines, osteoblast hFOB1.19 and fibroblast L929, were cultured in vitro. It was found that these two types of cells exhibited different responses on different membranes: the hFOB1.19 cells showed significant increase in cell proliferation with increase in surface roughness, whereas the L929 cells demonstrated an opposite trend, preferring to attach and grow on a flat surface. PHB membranes with different morphologies exhibit different cell compatibilities, which may be useful means for the architectural design of materials for tissue engineering. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
73.
Sheng‐Hsiung Yang Shiang‐Ying Chen Yu‐Chun Wu Chain‐Shu Hsu 《Journal of polymer science. Part A, Polymer chemistry》2007,45(15):3440-3450
A new series of poly(2,3‐diphenyl‐1,4‐phenylenevinylene) derivatives containing dendritic side groups were synthesized. Different generations of dendrons were integrated on the pendant phenyl ring to investigate their effect on optical and electrical properties of final polymers. Homopolymers can not be obtained via the Gilch polymerization because of sterically bulky dendrons. By controlling the feed ratio of different monomers during polymerization, dendron‐containing copolymers with high molecular weights were obtained. The UV–vis absorption and photoluminescent spectra of the thin films are pretty close; however, quantum efficiency is significantly enhanced with increasing the generation of dendrons. The electrochemical analysis reveals that hole‐injection is also improved by increasing dendritic generation. Double‐layer light‐emitting devices with the configuration of ITO/PEDOT:PSS/polymer/Ca/Al were fabricated. High generation dendrons bring benefit of improved device performance. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3440–3450, 2007 相似文献
74.
Chung‐Han Yu Min‐Shiang Kuo Ching‐Yi Chuang Gene‐Hsiang Lee Shao‐An Hua Prof. Bih‐Yaw Jin Prof. Dr. Shie‐Ming Peng 《化学:亚洲杂志》2014,9(11):3111-3115
Chirality control of helixes with the Δ (P) or Λ (M) form is interesting in various fields such as extended metal atom chains (EMACs), in which the metal backbones are helically wrapped by four ligands. Herein, we report two EMACs, Δ‐[Ni5((?)camnpda)4] and Λ‐[Ni5((+)camnpda)4], whose chiralities are controlled by chiral ligands with naphthyridine and camphorsulfonyl groups. There is a large energy difference (108 kcal mol?1) between the two helical structures with one chiral ligand. Furthermore, the electron communication between [Ni2]3+ units is more pronounced than in [Ni5(bna)4Cl2]2+ (bna=binaphthyridylamido). The results demonstrate control of small‐scale helical structure and set the stage for future development of chiral controlled base and nanoelectronic devices. 相似文献
75.
Dr. Liang‐Hsiang Chen Tarng‐Shiang Hu Dr. Peng‐Yi Huang Prof. Choongik Kim Ching‐Hao Yang Juin‐Jie Wang Dr. Jing‐Yi Yan Dr. Jia‐Chong Ho Dr. Cheng‐Chung Lee Prof. Ming‐Chou Chen 《Chemphyschem》2013,14(12):2772-2776
A solution‐processed anthradithiophene derivative, 5,11‐bis(4‐triethylsilylphenylethynyl)anthradithiophene (TESPE‐ADT), is studied for use as the semiconducting material in thin‐film transistors (TFTs). To enhance the electrical performance of the devices, two different kinds of solution processing (spin‐coating and drop‐casting) on various gate dielectrics as well as additional post‐treatment are employed on thin films of TESPE‐ADT, and p‐channel OTFT transport with hole mobilities as high as ~0.12 cm2 V?1 s?1 are achieved. The film morphologies and formed microstructures of the semiconductor films are characterized in terms of film processing conditions and are correlated with variations in device performance. 相似文献
76.
Keh-Dong Shiang 《Physics letters. A》1993,180(6):444-452
We propose in this paper a theoretical model to investigate surface self-diffusion of single adatoms on two different low-index planes, closely packed (001) and densely packed (111), of face-centered-cubic rhodium, nickel and copper metal crystals. Two realistic model potentials are applied to describe the interatomic interaction of the adatom-substrate systems. The first model is a Morse-type potential, which involves several empirical fittings of bulk of solid. The second, newly popular, potential was introduced by Sutton and Che, which incorporates many-body effects. With these potentials, conventional molecular dynamics (MD) is employed to obtain trajectories of the atoms. The average squared didplacements are computed for a range of initial kinetic energies, and the surface diffusion constants can be obtained by means of the Einstein relation. The estimated random walk exponential prefactors and activation energies exhibit an Arrhenius behavior, and are compared with previous results. 相似文献
77.
van der Klink JJ 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2001,148(1):147-154
It is shown that the NMR reciprocity theorem is a variant of a problem considered by Lorentz in 1895. This formulation is quite general and applies to electric-dipole-based as well as coil-based or resonator-based magnetic resonance probes. The reasoning is related to, but different from, the proof of the reciprocity theorem for radiofrequency networks and for transmit/receive antenna systems in telecommunications. The signal-to-noise ratio of the NMR experiment is also discussed in very general terms. 相似文献
78.
79.
Chih‐Ching Huang Prof. Yu‐Lun Hung Yen‐Chun Shiang Tai‐Yuan Lin Prof. Yu‐Shen Lin Chao‐Tsen Chen Prof. Huan‐Tsung Chang Prof. 《化学:亚洲杂志》2010,5(2):334-341
We have employed mannose‐modified gold nanodots (Man–Au NDs) as a luminescence sensor for the detection of the thyroid‐cancer marker thyroglobulin (Tg) in homogeneous solutions. The luminescent Man–Au NDs are prepared through the reaction of 2.9 nm‐diameter gold nanoparticles (Au NPs) with 11‐mercapto‐3,6,9‐trioxaundecyl‐α‐D ‐mannopyranoside (Man‐RSH) under the irradiation of a light‐emitting diode (LED). We have found that the irradiation enhances the quantum yield (~11 %), alters the emission wavelength and lifetimes, and shortens the preparation time. A luminescence assay has been developed for Tg based on the competition between Tg and Man–Au NDs for the interaction with the concanavalin A (Con A). Because luminescence quenching of the Man–Au NDs by Con A is inhibited by Tg selectivity, we have obtained a highly sensitive and selective assay for Tg. 相似文献
80.
A dedicated small‐angle X‐ray scattering beamline with a superconducting wiggler source at the NSRRC
Din‐Goa Liu Chien‐Hung Chang Chin‐Yen Liu Shih‐Hung Chang Jwei‐Ming Juang Yen‐Fang Song Kuan‐Li Yu Kuei‐Fen Liao Ching‐Shiang Hwang Hok‐Sum Fung Ping‐Chung Tseng Chi‐Yi Huang Liang‐Jen Huang Shih‐Chun Chung Mau‐Tsu Tang King‐Long Tsang Yu‐Shan Huang Chien‐Kuang Kuan Yi‐Chih Liu Keng S. Liang U‐Ser Jeng 《Journal of synchrotron radiation》2009,16(1):97-104
At the National Synchrotron Radiation Research Center (NSRRC), which operates a 1.5 GeV storage ring, a dedicated small‐angle X‐ray scattering (SAXS) beamline has been installed with an in‐achromat superconducting wiggler insertion device of peak magnetic field 3.1 T. The vertical beam divergence from the X‐ray source is reduced significantly by a collimating mirror. Subsequently the beam is selectively monochromated by a double Si(111) crystal monochromator with high energy resolution (ΔE/E? 2 × 10?4) in the energy range 5–23 keV, or by a double Mo/B4C multilayer monochromator for 10–30 times higher flux (~1011 photons s?1) in the 6–15 keV range. These two monochromators are incorporated into one rotating cradle for fast exchange. The monochromated beam is focused by a toroidal mirror with 1:1 focusing for a small beam divergence and a beam size of ~0.9 mm × 0.3 mm (horizontal × vertical) at the focus point located 26.5 m from the radiation source. A plane mirror installed after the toroidal mirror is selectively used to deflect the beam downwards for grazing‐incidence SAXS (GISAXS) from liquid surfaces. Two online beam‐position monitors separated by 8 m provide an efficient feedback control for an overall beam‐position stability in the 10 µm range. The beam features measured, including the flux density, energy resolution, size and divergence, are consistent with those calculated using the ray‐tracing program SHADOW. With the deflectable beam of relatively high energy resolution and high flux, the new beamline meets the requirements for a wide range of SAXS applications, including anomalous SAXS for multiphase nanoparticles (e.g. semiconductor core‐shell quantum dots) and GISAXS from liquid surfaces. 相似文献