全文获取类型
收费全文 | 488篇 |
免费 | 23篇 |
国内免费 | 1篇 |
专业分类
化学 | 401篇 |
晶体学 | 2篇 |
力学 | 1篇 |
数学 | 9篇 |
物理学 | 99篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 13篇 |
2015年 | 15篇 |
2014年 | 7篇 |
2013年 | 9篇 |
2012年 | 40篇 |
2011年 | 38篇 |
2010年 | 21篇 |
2009年 | 11篇 |
2008年 | 40篇 |
2007年 | 44篇 |
2006年 | 38篇 |
2005年 | 29篇 |
2004年 | 29篇 |
2003年 | 29篇 |
2002年 | 16篇 |
2001年 | 14篇 |
2000年 | 11篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1992年 | 10篇 |
1991年 | 4篇 |
1990年 | 9篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有512条查询结果,搜索用时 31 毫秒
41.
A. Casaburi M. Ejrnaes F. Mattioli A. Gaggero R. Leoni N. Martucciello S. Pagano M. Ohkubo R. Cristiano 《Journal of nanoparticle research》2011,13(11):6121-6131
The recent progress in the nanofabrication of superconducting films opens the road toward detectors with highly improved performances.
This is the case for superconducting nano-striplines where the thickness and the width are pushed down to the extreme limits
to realize detectors with unprecedented sensitivity and ultra fast response time. In this way quantum detectors for single
photons at telecommunication wavelengths and for macromolecules such as proteins can be realized. As is often the case in
applied nanotechnology, it is a challenge to make devices with the necessary macroscopic dimensions that are needed to interface
present technologies, while maintaining the performance improvements. For nano-stripline detectors, both the fast temporal
response and the device sensitivity is generally degraded when the area is increased. Here, we present how such detectors
can be scaled up to macroscopic dimensions without losing the performance of the nano-structured active elements by using
an innovative configuration. In order to realize ultrathin superconducting film the nano-layer is growth with a careful setup
of the deposition technique which guarantees high quality and thickness uniformity at the nano-scale size. The active nano-strips
are defined with the state-of-the-art electron beam nanolithography to achieve a highly uniform linewidth. We present working
detectors based on nano-strips with thicknesses 9–40 nm and widths of 100–1000 nm which exhibit unprecedented speed and area
coverage (40 × 40 μm2 for single photon detectors and 1 × 1 mm2 for single molecule detectors) based on niobium nitride thus enabling practical use of this nanotechnology. 相似文献
42.
43.
M Tanaka M Takahashi E Kuwahara O Koyama K Ohkubo T Yotsuyanagi 《Chemical & pharmaceutical bulletin》1992,40(6):1559-1562
The effects of dipotassium glycyrrhizinate (GLYK) on the dissolution behavior and bioavailability of amphotericin B (AMB) were investigated. The mixtures of AMB and GLYK were prepared at different molar ratios by lyophilization. Lyophilization resulted in amorphous AMB either alone or in the mixture. Dissolution rates of AMB of the mixtures were markedly faster than that of lyophilized AMB alone, which was followed by a decrease of dissolution. The initially-enhanced dissolution rate was likely to be due to the improvement of surface wettability of drug particles with GLYK rather than the amorphous state of AMB. A phase solubility study of AMB with GLYK indicated that the increasing solubility was caused by micellar solubilization. The in vitro release rate of AMB from suppositories containing the lyophilized mixtures was significantly accelerated by increasing the amount of GLYK. The rectal absorption of AMB from suppositories containing either the drug alone, a physical mixture or a lyophilized mixture was studied using rabbits. The absorption of the mixture (AMB/GLYK = 1/9) was about 35 times greater in the area under the serum concentration-time curve (0-24 h) than that of lyophilized AMB alone. These results suggest that GLYK is useful for improving the dissolution property of AMB and the bioavailability of the drug incorporated in suppositories. 相似文献
44.
In the (6Li,d) reaction on36Ar, the strongly excited seventeen levels were observed at excitation energies above 11 MeV in40Ca. On the basis of the result of the DWBA analysis, these levels may correspond to the members of the higher nodal α-clusterK n =O+ band with prinicpal quantum numberN=14. 相似文献
45.
Y. Kamii I. Waki H. Fujioka M. Oshima H. Miki M. Okuyama 《Applied Surface Science》2002,190(1-4):348-351
Electrical characteristics of Mg-doped p-GaN activated with Ni catalytic layers have been investigated by means of temperature-dependent Hall effect measurements. It has been revealed that the Ni layer on GaN enhances activation of the acceptor in the whole annealing temperature range. This enhancement is remarkable especially at temperatures below 500 °C and can be attributed to the catalytic effect for the hydrogen desorption. We have found that the donor concentrations in the samples activated with the Ni catalysts are also higher than those activated without Ni. This is probably due to the catalytic effect of Ni for the nitrogen desorption. In addition, it has been found that the ionization energies of the Mg acceptors in GaN activated with the Ni layer are decreased from 170 to 118 meV as the acceptor concentration increases. 相似文献
46.
The energy spectrum and α-spectroscopic factors of40Ca are calculated by using an α+36Ar orthogonality condition model. Overall agreement is obtained with the experimental data. The model successfully produces the parity-doubletK π=O + and O? α+36Ar cluster bands. It is shown that the coexistence and interference of α-cluster states and shell-model states are indispensable to understand the structure of40Ca. 相似文献
47.
W. Sato H. Ueno A. Taniguchi Y. Itsuki Y. Kasamatsu A. Shinohara K. Asahi Y. Ohkubo 《Journal of Radioanalytical and Nuclear Chemistry》2007,272(3):665-668
The time-differential perturbed angular correlation (TDPAC) method was applied to a study on the behavior of 140Ce atoms implanted in highly oriented pyrolytic graphite (HOPG). Exponential-type gradual attenuation of the directional anisotropy
of the relevant γ-ray cascade was observed in the perturbation patterns. From temperature dependence of the relaxation rate,
a thermally activated dynamic motion of the probe atoms was suggested. 相似文献
48.
Shuichi Ban Yoshiki Takano Naoki Ohkubo Hisanobu Hoya Yumiko Takahashi Kouichi Takase Kazuko Sekizawa 《Hyperfine Interactions》2005,165(1-4):95-99
The transition metal phosphorus trichalcogenides MnPS3 and the FePS3 are CdCl2 type layered compounds, where the transition metal ions form a hexagonal lattice. While these compounds order anti-ferromagnetically at low temperature, the magnetic structures are different. We have reported that these mixtures Mn0.5Fe0.5PS3 is a spin glass with a glass transition temperature T g=33.7 K. Then, in this work, we report that the results of the temperature variation of the 57Fe Mössbauer spectra of FePS3 and Mn0.5Fe0.5PS3, in detail. In the anti-ferromagnetic state of FePS3, the hyperfine magnetic field H int increases with decreasing temperature and the Isomer shift I. S. increases slightly with decreasing temperature. However in Mn0.5Fe0.5PS3, the two broadened peaks are observed and the two peaks became a single peak with decreasing temperature at about 50.0 K, which is higher than T g=33.7 K. In the spin glass Mn0.5Fe0.5PS3, the Mössbauer spectra suggest that the magnetic interactions exist far above T g. 相似文献
49.
It is suggested that weak coupling picture for theα-cluster states holds not only in the44Ti~40Ca region but also in the upper part of thesd-shell region. To confirm this experimentally, theα-clustering aspects of38Ar is investigated. 相似文献
50.
Coronenetetraimide‐Centered Cruciform Pentamers Containing Multiporphyrin Units: Synthesis and Sequential Photoinduced Energy‐ and Electron‐Transfer Dynamics 下载免费PDF全文
Prof. Taku Hasobe Koichi Ida Dr. Hayato Sakai Prof. Kei Ohkubo Prof. Shunichi Fukuzumi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(31):11196-11205
A series of coronenetetraimide (CorTIm)‐centered cruciform pentamers containing multiporphyrin units, in which four porphyrin units are covalently linked to a CorTIm core through benzyl linkages, were designed and synthesized to investigate their structural, spectroscopic, and electrochemical properties as well as photoinduced electron‐ and energy‐transfer dynamics. These systems afforded the first synthetic case of coroneneimide derivatives covalently linked with dye molecules. The steady‐state absorption and electrochemical results indicate that a CorTIm and four porphyrin units were successfully characterized by the corresponding reference monomers. In contrast, the steady‐state fluorescence measurements demonstrated that strong fluorescence quenching relative to the corresponding monomer units was observed in these pentamers. Nanosecond laser flash photolysis measurements revealed the occurrence of intermolecular electron transfer from triplet excited state of zinc porphyrins to CorTIm. Femtosecond laser‐induced transient absorption measurements for excitation of the CorTIm unit clearly demonstrate the sequential photoinduced energy and electron transfer between CorTIm and porphyrins, that is, occurrence of the initial energy transfer from CorTIm (energy donor) to porphyrins (energy acceptor) and subsequent electron transfer from porphyrins (electron donor) to CorTIm (electron acceptor) in these pentamers, whereas only the electron‐transfer process from porphyrins to CorTIm was observed when we mainly excite porphyrin units. Finally, construction of high‐order supramolecular patterning of these pentamers was performed by utilizing self‐assembly and physical dewetting during the evaporation of solvent. 相似文献