全文获取类型
收费全文 | 30478篇 |
免费 | 1036篇 |
国内免费 | 13篇 |
专业分类
化学 | 20943篇 |
晶体学 | 226篇 |
力学 | 560篇 |
数学 | 4142篇 |
物理学 | 5656篇 |
出版年
2023年 | 253篇 |
2022年 | 171篇 |
2021年 | 341篇 |
2020年 | 508篇 |
2019年 | 458篇 |
2018年 | 673篇 |
2017年 | 617篇 |
2016年 | 1190篇 |
2015年 | 954篇 |
2014年 | 951篇 |
2013年 | 1997篇 |
2012年 | 2211篇 |
2011年 | 2377篇 |
2010年 | 1336篇 |
2009年 | 1071篇 |
2008年 | 1978篇 |
2007年 | 1943篇 |
2006年 | 1693篇 |
2005年 | 1523篇 |
2004年 | 1231篇 |
2003年 | 953篇 |
2002年 | 841篇 |
2001年 | 645篇 |
2000年 | 556篇 |
1999年 | 411篇 |
1998年 | 293篇 |
1997年 | 208篇 |
1996年 | 334篇 |
1995年 | 219篇 |
1994年 | 221篇 |
1993年 | 265篇 |
1992年 | 235篇 |
1991年 | 154篇 |
1990年 | 137篇 |
1989年 | 119篇 |
1988年 | 121篇 |
1987年 | 121篇 |
1986年 | 115篇 |
1985年 | 177篇 |
1984年 | 143篇 |
1983年 | 119篇 |
1982年 | 103篇 |
1981年 | 98篇 |
1980年 | 76篇 |
1979年 | 93篇 |
1978年 | 80篇 |
1977年 | 73篇 |
1976年 | 76篇 |
1975年 | 70篇 |
1973年 | 81篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
171.
V. V. Glagolev R. M. Lebedev G. D. Pestova S. S. Shimansky M. Kravčíková M. Seman L. Šándor A. Dirner J. Hlaváčová G. Martinská J. Urbán K. U. Khairetdinov H. Braun J. P. Gerber P. Juillot A. Michalon A. K. Kacharava Z. P. Menteshashvili N. S. Nioradze Z. R. Salukvadze T. Sobczak J. Stepaniak 《Zeitschrift fur Physik C Particles and Fields》1993,60(3):421-425
4He-p collisions at two values of4He momenta 8.6 GeV/c and 13.6 GeV/c as well as the3He-p collisions at 13.5 GeV/c have been studies using the one-meter JINR hydrogen bubble chamber. Total, elastic, topological and reaction cross sections have been measured. The cross sections have been determined on a sample of minimum biased events. 相似文献
172.
X-ray photoelectron and Auger spectroscopies were used to examine surface bonding and overlayer growth during palladium and copper deposition onto films of fullerene, C60 The results were consistent with metal cluster formation on C60. The observed positive core electron binding energy shifts in small metallic clusters supported on C60 were shown to originate in metal-fullerene interaction accompanied by charge transfer. Palladium-fullerene intermixing at temperatures as low as ss 50°C was observed for small Pd coverages. 相似文献
173.
Vladimír Janiš 《International Journal of Theoretical Physics》1993,32(10):1893-1895
We show that the Boolean power of an orthomodular latticeL is atomic if and only if bothL and the underlying Boolean algebraB are atomic. We describe the set of all atoms in the Boolean power. 相似文献
174.
This paper presents the results of plasma temperature and pressure calculations in the parallel plate accelerator during the accelerating process. The plasma pressure is calculated by means in Dalton's law. 相似文献
175.
Francisco Eduardo de Sousa Filho João Hermínio da Silva Antônio Álamo Feitosa Saraiva Deyvid Dennys S. Brito Bartolomeu Cruz Viana Bruno Tavares de Oliveira Abagaro Paulo de Tarso Cavalcante Freire 《Brazilian Journal of Physics》2011,41(4-6):275-280
X-ray diffraction was combined with X-ray energy-dispersion, Fourier-transform infrared, and Raman spectroscopies to study the fossilization of a Cretaceous specimen of the plant Brachyphyllum castilhoi, a fossil from the Ipubi Formation, in the Araripe Sedimentary Basin, Northeastern Brazil. Among the possible fossilization processes, which could involve pyrite, silicon oxide, calcium oxide, or other minerals, we were able to single out pyritization as the central mechanism producing the fossil, more than 100 million years ago. In addition to expanding the knowledge of the Ipubi Formation, this study shows that, when combined with other experimental techniques, Raman spectroscopy is a valuable tool at the paleontologist’s disposal. 相似文献
176.
M. Bello-Jiménez C. Cuadrado-Laborde A. Diez J. L. Cruz M. V. Andrés A. Rodríguez-Cobos 《Applied physics. B, Lasers and optics》2013,110(1):73-80
Active mode-locking of long-cavity all-fiber ring laser based on broad bandwidth in-fiber acousto-optic modulator (AOM) is reported. The proposed AOM combines the advantages of intermodal coupling induced by standing flexural acoustic waves in a double-ended tapered fiber. We focus our attention on the effects of large tapered transitions to improve the bandwidth modulation. Our approach permits the implementation of broad modulation bandwidth (13 nm), high modulation depth (50 %), and low optical loss (1.1 dB) in an 80-μm configuration. The effects of the AOM in the laser performance are also investigated. Transform-limit optical pulses of 25 ps temporal width and 2.7 W peak power were obtained at 2.46 MHz repetition rate. 相似文献
177.
Mariana Orellana Federico García Florencia A. Teppa Pannia Gustavo E. Romero 《General Relativity and Gravitation》2013,45(4):771-783
The effects implied for the structure of compact objects by the modification of General Relativity (GR) produced by the generalization of the Lagrangian density to the form $f(R)=R+\alpha R^2$ , where $R$ is the Ricci curvature scalar, have been recently explored. It seems likely that this squared-gravity may allow heavier Neutron Stars (NSs) than GR. In addition, these objects can be useful to constrain free parameters of modified-gravity theories. The differences between alternative gravity theories are enhanced in the strong gravitational regime. In this regime, because of the complexity of the field equations, perturbative methods become a good choice to treat the problem. Following previous works in the field, we performed a numerical integration of the structure equations that describe NSs in $f(R)$ -gravity, recovering their mass-radius relations, but focusing on particular features that arise from this approach in the profiles of the NS interior. We show that these profiles run in correlation with the second-order derivative of the analytic approximation to the Equation of State (EoS), which leads to regions where the enclosed mass decreases with the radius in a counter-intuitive way. We reproduce all computations with a simple polytropic EoS to separate zeroth-order modified gravity effects. 相似文献
178.
Nati Salvadó Salvador Butí Marine Cotte Gianfelice Cinque Trinitat Pradell 《Applied Physics A: Materials Science & Processing》2013,111(1):47-57
A representative selection of green paintings from fifteenth century Catalonia and the Crown of Aragon are analyzed by a combination of synchrotron radiation microanalytical techniques including FTIR, XRD, and XRF. The green pigments themselves are found to be a mixture of copper acetates/basic copper acetates and basic copper chlorides. Nevertheless, a broader range of green shades were obtained by mixing the green pigment with yellow, white, and blue pigments and applied forming a sequence of micrometric layers. Besides the nature of the pigments themselves, degradation and reaction products, such as carboxylates, formates and oxalates were also identified. Some of the copper based compounds, such as the basic copper chloride, may be either part of the original pigment or a weathering product. The high resolution, high brilliance, and small footprint of synchrotron radiation proved to be essential for the analysis of those submillimetric paint layers made of a large variety of compounds heterogeneous in nature and distribution and present in extremely low concentrations. 相似文献
179.
L. Ortíz 《General Relativity and Gravitation》2013,45(2):427-448
We review the relation between AdS spacetime in 1 $+$ 2 dimensions and the BTZ black hole (BTZbh). Later we show that a ground state in AdS spacetime becomes a thermal state in the BTZbh. We show that this is true in the bulk and in the boundary of AdS spacetime. The existence of this thermal state is tantamount to say that the Unruh effect exists in AdS spacetime and becomes the Hawking effect for an eternal BTZbh. In order to make this we use the correspondence introduced in algebraic holography between algebras of quasi-local observables associated to wedges and double cones regions in the bulk of AdS spacetime and its conformal boundary respectively. Also we give the real scalar quantum field as a concrete heuristic realization of this formalism. 相似文献
180.
Paolo Muratore-Ginanneschi Carlos Mejía-Monasterio Luca Peliti 《Journal of statistical physics》2013,150(1):181-203
We derive the equations governing the protocols minimizing the heat released by a continuous-time Markov jump process on a one-dimensional countable state space during a transition between assigned initial and final probability distributions in a finite time horizon. In particular, we identify the hypotheses on the transition rates under which the optimal control strategy and the probability distribution of the Markov jump problem obey a system of differential equations of Hamilton-Jacobi-Bellman-type. As the state-space mesh tends to zero, these equations converge to those satisfied by the diffusion process minimizing the heat released in the Langevin formulation of the same problem. We also show that in full analogy with the continuum case, heat minimization is equivalent to entropy production minimization. Thus, our results may be interpreted as a refined version of the second law of thermodynamics. 相似文献