全文获取类型
收费全文 | 11921篇 |
免费 | 1041篇 |
国内免费 | 341篇 |
专业分类
化学 | 4604篇 |
晶体学 | 58篇 |
力学 | 581篇 |
综合类 | 30篇 |
数学 | 4479篇 |
物理学 | 3551篇 |
出版年
2023年 | 75篇 |
2022年 | 167篇 |
2021年 | 175篇 |
2020年 | 212篇 |
2019年 | 277篇 |
2018年 | 238篇 |
2017年 | 217篇 |
2016年 | 365篇 |
2015年 | 303篇 |
2014年 | 387篇 |
2013年 | 966篇 |
2012年 | 486篇 |
2011年 | 566篇 |
2010年 | 414篇 |
2009年 | 686篇 |
2008年 | 782篇 |
2007年 | 869篇 |
2006年 | 713篇 |
2005年 | 517篇 |
2004年 | 504篇 |
2003年 | 449篇 |
2002年 | 293篇 |
2001年 | 305篇 |
2000年 | 301篇 |
1999年 | 264篇 |
1998年 | 308篇 |
1997年 | 173篇 |
1996年 | 195篇 |
1995年 | 194篇 |
1994年 | 197篇 |
1993年 | 151篇 |
1992年 | 147篇 |
1991年 | 95篇 |
1990年 | 93篇 |
1989年 | 103篇 |
1988年 | 91篇 |
1987年 | 97篇 |
1986年 | 83篇 |
1985年 | 104篇 |
1984年 | 89篇 |
1983年 | 63篇 |
1982年 | 117篇 |
1981年 | 86篇 |
1980年 | 78篇 |
1979年 | 53篇 |
1978年 | 73篇 |
1977年 | 65篇 |
1976年 | 70篇 |
1975年 | 10篇 |
1973年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
N. S. Kazak E. G. Katranji I. A. Utkin A. A. Ryzhevich A. N. Khilo 《Journal of Applied Spectroscopy》2004,71(5):697-701
The phenomenon of self-diffraction of Bessel light beams (BLB) in a nonlinear liquid medium has been studied experimentally and theoretically for the first time. Diffraction maxima which do not correspond to integer orders for an induced periodic structure have been registered. It has been shown that the appearance of these maxima is due to the initial BLB modulation, which can be caused by the departure of the axicon refracting surface from the ideal conical surface, as well as by the imperfection of the form of the Gaussian beam incident on the axicon. 相似文献
52.
53.
Sylvia Pulmannová 《International Journal of Theoretical Physics》2003,42(5):907-919
Tensor products of quantum logics and effect algebras with some known problems are reviewed. It is noticed that although tensor products of effect algebras having at least one state exist, in the category of complex Hilbert space effect algebras similar problems as with tensor products of projection lattices occur. Nevertheless, if one of the two coupled physical systems is classical, tensor product exists and can be considered as a Boolean power. Some applications of tensor products (in the form of Boolean powers) to quantum measurements are reviewed. 相似文献
54.
55.
D. Behera T. Mohanty S. K. Dash T. Banerjee D. Kanjilal N. C. Mishra 《Radiation measurements》2003,36(1-6):125-129
Swift heavy ions (SHI) with electronic energy loss exceeding a value of 14.4 keVnm−1 create amorphized latent tracks in YBCO type superconductors. In the low fluence regime of an ion beam where tracks do not overlap, a decrease of the superconducting transition temperature as probed through resistivity studies, is not expected due to availability of percolating current paths. The present study however shows Tc decrease by about 1–3 K in thin films of YBCO when irradiated by 250 MeVAg ions at 79 K at a fluence of 5×1010–1×1012 ionscm−2. The highest fluence used in the present study is three times less than the fluence where track overlapping becomes significant. The Tc tends to increase towards the preirradiation value on annealing the films at room temperature. To explain this unusual result, we consider the effect of ion irradiation in inducing materials modification not only through creation of amorphized latent tracks along the ion path, but also through creation of atomic disorder in the oxygen sublattice in the Cu–O chains of YBCO by the secondary electrons. These electrons are emitted radially from the tracks during the passage of the SHI. Considering the correlation between the charge state of copper and its oxygen coordination, we show in particular that the latter process is a consequence of the inelastic interaction of the SHI induced low-energy secondary electrons with the YBCO lattice, which result in chain oxygen disorder and Tc decrease. 相似文献
56.
A. Vukics H. Ritsch 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(3):585-599
We present a framework for efficiently performing Monte Carlo
wave-function simulations in cavity QED with moving particles. It
relies heavily on the object-oriented programming paradigm as realised
in C++, and is extensible and applicable for simulating open
interacting qua
ntum dynamics in general. The user is provided with a
number of “elements”, e.g. pumped moving particles, pumped lossy
cavity modes, and various interactions to compose complex interacting
systems, which contain several particles moving in electromagnetic
fields of various configurations, and perform wave-function
simulations on such systems. A number of tools are provided to
facilitate the implementation of new elements. 相似文献
57.
M. Feng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(3):371-377
The Raman interaction of a ultracold ion trapped with two travelling wave lasers is studied analytically with series solutions,
in the absence of the rotating wave approximation (RWA) and without restrictions of both the Lamb-Dicke limit and the weak
excitation regime. The comparison is made between our solutions and those obtained under the RWA in order to demonstrate the
validity region of the RWA. As a practical example, the preparation of Schr?dinger-cat states is proposed beyond the weak
excitation regime, using our calculations.
Received 12 March 2001 and Received in final form 16 October 2001 相似文献
58.
M. C. Crabb 《Journal of Fixed Point Theory and Applications》2007,2(2):171-193
We describe an equivariant version (for actions of a finite group G) of Dold’s index theory, [10], for iterated maps. Equivariant Dold indices are defined, in general, for a G-map U → X defined on an open G-subset of a G-ANR X (and satisfying a suitable compactness condition). A local index for isolated fixed-points is introduced, and the theorem
of Shub and Sullivan on the vanishing of all but finitely many Dold indices for a continuously differentiable map is extended
to the equivariant case. Homotopy Dold indices, arising from the equivariant Reidemeister trace, are also considered.
相似文献
59.
60.
Experiments for the determination of mono-, di and tri-butyltin (MBT, DBT and TBT) by hydride generation/gas chromatography/atomic absorption spectrometry in various matrices (sediment, suspended matter, mussel, algae and water) have revealed that poor butyltin recoveries are obtained in sediments displaying high sulphur and hydrocarbon contents; very poor recoveries were also observed for TBT in sediments with high chlorophyll pigment contents as well as in algal samples. It was however not clear whether the hydride generatin was inhibited by these infering compounds, as was previously assumed in the case of hydrocarbons, or whether interferences affected the atomization rate. Further studies were performed to solve this problem in order to validate this method in the case of analyses of, for example, oil-contaminated sediment and algae. This paper presents the results obtained. It is concluded here that the poor recoveries were due to an inhibition of hydride generation rather than to interference at the atomization stage. 相似文献