全文获取类型
收费全文 | 346篇 |
免费 | 13篇 |
专业分类
化学 | 238篇 |
晶体学 | 1篇 |
力学 | 2篇 |
数学 | 34篇 |
物理学 | 84篇 |
出版年
2023年 | 2篇 |
2022年 | 10篇 |
2021年 | 12篇 |
2020年 | 14篇 |
2019年 | 7篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 15篇 |
2015年 | 7篇 |
2014年 | 10篇 |
2013年 | 16篇 |
2012年 | 16篇 |
2011年 | 19篇 |
2010年 | 9篇 |
2009年 | 7篇 |
2008年 | 15篇 |
2007年 | 17篇 |
2006年 | 14篇 |
2005年 | 11篇 |
2004年 | 13篇 |
2003年 | 10篇 |
2002年 | 10篇 |
2001年 | 10篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 11篇 |
1993年 | 3篇 |
1992年 | 9篇 |
1990年 | 5篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1966年 | 2篇 |
1965年 | 2篇 |
1964年 | 2篇 |
1938年 | 4篇 |
1935年 | 2篇 |
1934年 | 2篇 |
1932年 | 1篇 |
1930年 | 3篇 |
1929年 | 3篇 |
1927年 | 1篇 |
排序方式: 共有359条查询结果,搜索用时 15 毫秒
351.
352.
T. Ida K. Ishibashi K. Tsukagoshi B. W. Alphenaar Y. Aoyagi 《Superlattices and Microstructures》2000,27(5-6)
Transport measurements on a bundle of single-walled carbon nanotubes have been made below 4.2 K as a function of side gate and source–drain bias voltage. The transport of an individual nanotube is described by the Coulomb blockade effect. The zero-dimensional quantum states of the nanotube become clear for measurements of large bias voltage. In addition, we present preliminary results of microwave application to the SWNT dot, and the results can be qualitatively explained by classical coupling to the dot. 相似文献
353.
Sol-gel process has gained tremendous attention in past decades for the preparation of pure and composite material for numerous
applications. Organically modified sol-gel glasses (ormosils) have hybrid properties of rigid inorganic silica matrix and
organic functionalities. Ormosils provide ambient environment for bio-molecules encapsulation and such systems have been used
widely for biosensor applications. Biological elements including enzymes, antibodies, antigens, DNA, whole cells, tissues,
proteins, biologically derived material, and biomimetic materials provide the possibility of biological recognition to the
device and transducer to detect the biological signals with the help of associated electronics and software to amplify these
signals into a readable form for the user. In this review we report on the formation of sol-gel based composite materials
primarily on ormosil along with carbon nano tubes, metal nano particles, mediators, inorganic complexes, polymers, ionomers
and biological materials and cite the electrochemical sensor/biosensor system based on it. 相似文献
354.
Ida BN Fudacz PS Pulsifer DH Standard JM 《The journal of physical chemistry. A》2006,110(17):5831-5838
A series of donor-acceptor complexes containing sulfur trioxide have been studied in the gas and condensed phases using density functional theory. The condensed phase is represented using the polarizable continuum model. The systems investigated include complexes of nitrogen-containing donor molecules, (CH(3))(n)H(3-n)N (n = 0-3), with SO(3) and complexes of oxygen-containing donor molecules, (CH(3))(m)H(2-m)O (m = 0-2), with SO(3). Significant differences are observed between the gas- and condensed-phase properties of the complexes as a result of the ability of the condensed-phase medium to support higher charge separation between the donor and acceptor. The gas/condensed-phase behavior of two nitrogen-containing complexes, (CH(3))H(2)N-SO(3) and (CH(3))(2)HN-SO(3), has been investigated for the first time. These complexes exhibit properties intermediate to the previously observed H(3)N-SO(3) and (CH(3))(3)N-SO(3) complexes. Systematic trends in the gas- and condensed-phase structure and properties have been observed as methyl groups are added to the donor molecule. In addition, two oxygen-containing complexes, CH(3)OH-SO(3) and (CH(3))(2)O-SO(3), have been characterized for the first time. The differences between the gas- and condensed-phase properties of the oxygen-containing complexes are, in many cases, larger than those of the nitrogen-containing complexes, and therefore they represent an intriguing new class of complexes for potential experimental observation. Finally, a strong correlation between the charge transfer and binding energy has been obtained for both the nitrogen- and oxygen-containing complexes of sulfur trioxide. 相似文献
355.
Ida S Araki K Unal U Izawa K Altuntasoglu O Ogata C Matsumoto Y 《Chemical communications (Cambridge, England)》2006,(34):3619-3621
Multilayer oxide films consisting of a TiO-Eu3+-TiO-Tb3+-NbO-Tb3+-NbO-Eu3+ unit which was prepared by the layer-by-layer technique, showed photoluminescence with a high intensity containing both red and green lights. 相似文献
356.
Carbon nanotubes (CNT) polymer composites have shown potential applications for sensor/biosensor fabrication. Methods for
preparation, characteristics are highlighted and future aspects are explored. Various analytes and polymeric materials have
been cited to prove the importance of polymer/CNT composite systems in sensor technology. 相似文献
357.
Nonylphenols ethoxylates (NPEs) are surface active agents (surfactants) commonly used in cleaning products, in industrial processes, agricultural formulations and paints. They are found in sewage, municipal wastewaters and industrial effluents, and as contaminants in water bodies. Accumulating data suggest that exposure to NPEs can adversely affects functional properties of the neurologic, reproductive, immune, and endocrine systems. In order to examine whether NPEs exert similar damaging effects on the cardiovascular system, we used an amphibian model to examine the ultrastructural alterations of the ventricular myocardium following exposure to NPEs. Adult Lissotriton italicus in the aquatic phase were exposed to NPE10 (100 μg/L, ppb) for 96 h. Heart specimens were collected from a total of 10 individuals and processed for scanning and transmission electron microscopy. Our ultrastructural examinations demonstrated that amphibian ventricle is susceptible to the effects of NPEs. The most pronounced alterations were observed in the membrane compartments of both myocardial and endothelial cells as demonstrated by the presence of swollen mitochondria with disrupted cristae and dilated rough endoplasmic reticulum. We suggest that destabilization of the lipid milieu within membranes might represent one of the potential mechanisms by which NPEs exert their toxic effects on amphibian heart. 相似文献
358.
359.
UV-vis spectra of homopolymers and copolymers of 2-aminobenzoic acid (OAB) and 2-methoxyaniline (OMA) were analyzed in order to obtain information about the oxidation state and proton doping level of these polymers. Dimethyl sulfoxide (DMSO) was used as a solvent in which protonated forms of polyanilines are preserved and a mixture of N-methyl-2-pyrrolidone and triethylamine (0.5 %) as a solvent (NMP/TEA) in which polyanilines are assumed to be non-protonated. Polymers were prepared in the emeraldine salt form, externally doped with HCl. It was found that only external doping is eliminated in NMP/TEA while internal doping by carboxylate groups bound in OAB units remains operative. Since doped quinoid units do not contribute to the quinoid band (Q-band at 630 nm), the intensity ratio of the Q-band and benzenoid band (B-band at 320 nm) cannot be simply correlated with the oxidation state of poly(OMA-co-OAB) copolymers in contrast to poly(OMA) and polyaniline. Spectra of copolymers with less than 60 % of OMA units as well as those of poly(OAB) in DMSO and NMP/TEA are almost identical due to internal doping, which is proposed to lead to structures in which main-chain protons are coulombically bound with immobile carboxylate anions. In the spectra of copolymers with less than 60 % of OMA units, a well-resolved band occurs at 500 nm, which can be ascribed to alternating or close-to-alternating sequences of OMA and OAB units. 相似文献