全文获取类型
收费全文 | 624篇 |
免费 | 14篇 |
国内免费 | 7篇 |
专业分类
化学 | 458篇 |
晶体学 | 9篇 |
力学 | 16篇 |
数学 | 44篇 |
物理学 | 118篇 |
出版年
2022年 | 5篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2017年 | 8篇 |
2016年 | 5篇 |
2015年 | 12篇 |
2014年 | 16篇 |
2013年 | 38篇 |
2012年 | 21篇 |
2011年 | 33篇 |
2010年 | 22篇 |
2009年 | 20篇 |
2008年 | 33篇 |
2007年 | 34篇 |
2006年 | 33篇 |
2005年 | 28篇 |
2004年 | 36篇 |
2003年 | 21篇 |
2002年 | 17篇 |
2001年 | 15篇 |
2000年 | 16篇 |
1999年 | 5篇 |
1998年 | 8篇 |
1997年 | 8篇 |
1996年 | 15篇 |
1995年 | 9篇 |
1994年 | 10篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 10篇 |
1988年 | 9篇 |
1987年 | 4篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1976年 | 3篇 |
1975年 | 7篇 |
1974年 | 8篇 |
1973年 | 3篇 |
1971年 | 4篇 |
1970年 | 5篇 |
1961年 | 3篇 |
排序方式: 共有645条查询结果,搜索用时 15 毫秒
61.
T.Nakagawa M.Kidera Y.Higurasi J.Ohnishi T.Kageyama T.Aihara A.Goto Y.Yano 《中国物理 C》2007,31(Z1):133-136
We measured the main plasma parameters(density of electron,temperature of electron and ion confinement time)and beam intensity of various heavy ions as a function of B_(min).The B_(min) strongly affects the field gradient at the resonance zone,consequently the plasma parameters and beam intensity are changed. Based on these experimental results,we started to construct new 18GHz ECRIS and make a detailed design of the 28GHz SC-ECRIS for RIKEN RI beam factory project. 相似文献
62.
63.
Masafumi Yano Yorichika Okino Yuji Ichihara Masakazu Tatsumi Munetaka Oyama Kazunobu Sato Takeji Takui 《Polyhedron》2009,28(9-10):1764-1767
Three highly π-extended tetraaryl-1,3-phenylenediamines for charged high-spin molecular systems were successfully synthesized using Suzuki coupling. Their electrochemical and spectroscopic properties were also examined. They showed blue fluorescence. The dications derived from highly π-extended tetraaryl-1,3-phenylenediamines were generated and characterized by electron transfer stopped-flow method. 相似文献
64.
65.
Hidekazu Miyaji Junko Fujimoto Riho Mabuchi Moeno Okumura Shoichiro Goto Youtaro Honda 《Tetrahedron letters》2017,58(37):3623-3627
A novel molecular sensor using anthracene bearing two amidopyridines emits blue fluorescence in the presence of succinic acid and green fluorescence in the presence of malonic acid, and its fluorescence intensity increased upon binding. Using this molecular sensor, we succeeded in detecting the difference of one carbon atom between succinic acid and malonic acid with the naked-eye. Furthermore, when methylmalonic acid was dissolved in urine to provide a model system for methylmalonic aciduria, the fluorescence changed from blue to green, and methylmalonic acid was successfully detected with the naked-eye. 相似文献
66.
Lisman Suryanegara Antonio Norio Nakagaito Hiroyuki Yano 《Cellulose (London, England)》2010,17(4):771-778
Polylactic acid (PLA) in a crystallized state has mechanical properties at high temperatures superior to PLA in an amorphous state. However, a long annealing time is required to fully crystallize PLA. In this study, microfibrillated cellulose (MFC)-reinforced partially crystallized PLA composites were produced, with the goal of reducing the time required to fabricate PLA parts. A series of PLA/MFC composites at a fiber content of 10 wt% from degree of crystallinity (Xc) 0 to 43% was obtained by annealing at 80 °C. Although the annealing time required to obtain a composite (Xc: 17%) was only around one-seventh of the 20 min needed to fully crystallize neat PLA (Xc: 41%), both materials had comparable rigidity above the glass transition temperature (T g) and creep deformation at around T g. These results showed that partially crystallized PLA/MFC composite can replace fully crystallized neat PLA. 相似文献
67.
Bending tests and X-ray diffraction studies were conducted on oven-dried wood samples (Picea jezoensis Carr.) treated with various concentrations of aqueous NaOH solution to investigate the influence of alkali treatment on the
longitudinal contraction, bending properties, and cellulose structure. The length of the wood samples decreased and the density
increased at NaOH concentrations greater than 10%. The Young’s modulus and the specific Young’s modulus decreased and the
strain at yield increased for the same concentration range. However, the stress at yield was almost constant for all concentration
ranges. X-ray diffraction analysis showed that lattice transformation from cellulose I to cellulose II did not occur during
alkali treatment and the crystallinity index decreased at NaOH concentrations greater than 10%. The crystallinity index was
linearly correlated with the changes in longitudinal contraction and the bending properties, which indicates that the increase
in the proportion of amorphous components of the cellulose influences the longitudinal contraction and the bending properties
of wood samples during alkali treatment. 相似文献
68.
This study examined the relationship between the functions of plant cells and the characteristics of cellulose microfibril
aggregates in the cell walls. For this purpose, the mature bamboo (Phyllostachys pubescens) culm was separated into fiber and parenchyma cells, and then the morphological and physical properties of the cellulose
microfibril aggregates isolated from both cells were compared. SEM observations revealed that both fiber and parenchyma cells
consist of similar microfibril aggregates approximately 15–20 nm in width. Moreover, X-ray analysis and the tensile tests
of the sheets prepared from the microfibril aggregates showed that the cellulose microfibrils isolated from fiber and parenchyma
cells had almost the same cellulose crystallinity and longitudinal Young’s modulus in the dry state. These results suggest
that all the cellulose microfibrils synthesized in the same individual exhibit the same characteristics in the dry state regardless
of cell function. 相似文献
69.
The inelastic collisional effect on a shock layer of a dilute granular gas with a heated wall is numerically studied. To investigate
the inelastic collisional effect via the gain term in the inelastic Boltzmann equation on the shock layer, an inelastic Bhatnagar-Gross-Krook
(BGK) type equation, whose loss term is equivalent to that in the inelastic Boltzmann equation, is formulated on the basis
of the kinetic theory of the granular gas. The inelastic BGK-type equation formulated for a hard-sphere particle is generalized
to that for an inverse power law (IPL) molecule. Numerical results in a weakly inelastic regime confirm the nonequilirium
contribution to the cooling rate, when the collision frequency depends on the particle velocity. The profile of the negative
high-velocity tail of the distribution function in the generation regime of the shock wave obtained by the Direct Simulation
Monte Carlo method is higher than that obtained by the proposed BGK-type equation when the collision frequency depends on
the particle velocity because of the inelastic collisional effect via the gain term in the inelastic Boltzmann equation, which
is not included in the proposed BGK-type equation. 相似文献
70.
B. Shinozaki S. Takada N. Kokubo K. Makise K. Mitsuishi K. Yamada K. Yano H. Nakamura 《Physica C: Superconductivity and its Applications》2011,471(21-22):717-720
In order to investigate the relation among the superconducting transition Tc, carrier density n, resistivity ρ and the microstructure in the polycrystalline (In2O3)1?x–(ZnO)x films, we prepared specimen films by post annealing of amorphous films with x = 0.025 at various annealing temperature Ta and for annealing time ta = 1 h and 4 h. As for microstructures, we have investigated the distribution of elements by scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS). We have found followings: (1) The annealed films clearly show the superconductivity of which Tc depends on Ta, ta and n. This indicates that the superconductivity is determined by the combination of crystallinity and carrier density. (2) The data on STEM–EELS spectra mapping of indium plasmon indicate that droplets of the pure indium phase exist inside a film, where the distribution of these droplets dispersed. Therefore, it seems that droplets do not form an electrical conducting path, that is, it is possible that observed superconductivity is due to intrinsic characteristic of polycrystalline (In2O3)1?x–(ZnO)x films. 相似文献