全文获取类型
收费全文 | 204205篇 |
免费 | 1714篇 |
国内免费 | 592篇 |
专业分类
化学 | 102382篇 |
晶体学 | 3341篇 |
力学 | 9291篇 |
综合类 | 5篇 |
数学 | 22472篇 |
物理学 | 69020篇 |
出版年
2021年 | 1658篇 |
2020年 | 1797篇 |
2019年 | 2000篇 |
2018年 | 2700篇 |
2017年 | 2602篇 |
2016年 | 3766篇 |
2015年 | 2305篇 |
2014年 | 3616篇 |
2013年 | 9086篇 |
2012年 | 7241篇 |
2011年 | 8739篇 |
2010年 | 6043篇 |
2009年 | 5911篇 |
2008年 | 7913篇 |
2007年 | 8083篇 |
2006年 | 7728篇 |
2005年 | 6895篇 |
2004年 | 6431篇 |
2003年 | 5654篇 |
2002年 | 5493篇 |
2001年 | 6427篇 |
2000年 | 4934篇 |
1999年 | 3799篇 |
1998年 | 3039篇 |
1997年 | 3046篇 |
1996年 | 2795篇 |
1995年 | 2615篇 |
1994年 | 2464篇 |
1993年 | 2342篇 |
1992年 | 2692篇 |
1991年 | 2674篇 |
1990年 | 2603篇 |
1989年 | 2396篇 |
1988年 | 2451篇 |
1987年 | 2449篇 |
1986年 | 2280篇 |
1985年 | 2961篇 |
1984年 | 3215篇 |
1983年 | 2631篇 |
1982年 | 2801篇 |
1981年 | 2771篇 |
1980年 | 2637篇 |
1979年 | 2727篇 |
1978年 | 2823篇 |
1977年 | 2822篇 |
1976年 | 2888篇 |
1975年 | 2670篇 |
1974年 | 2645篇 |
1973年 | 2776篇 |
1972年 | 1763篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
81.
E. A. Ekimov E. L. Gromnitskaya D. A. Mazalov A. F. Pal’ V. V. Pichugin S. Gierlotka B. Palosz J. A. Kozubowski 《Physics of the Solid State》2004,46(4):755-757
Superhard nanodiamond-SiC ceramics are prepared by infiltrating liquid Si into porous nanodiamond compacts under pressure.
Synthesized samples are 2.2 mm thick and 3–4 mm in diameter. The effect of particle size of dynamically synthesized nanodiamond
powders on silicon infiltration and SiC phase formation is studied. It is established that silicon does not penetrate into
the pores of nanodiamond powders if the original particle size is smaller than 0.5–1.0 μm. The critical pore size for infiltration
is 100–200 nm. A study of the microstructure of the samples showed the presence of the nanometer-and submicron-scale SiC phase.
The ultrasound velocities are measured in the prepared compacts, and the elastic moduli are calculated.
__________
Translated from Fizika Tverdogo Tela, Vol. 46, No. 4, 2004, pp. 734–736.
Original Russian Text Copyright ? 2004 by Ekimov, Gromnitskaya, Mazalov, Pal’, Pichugin, Gierlotka, Palosz, Kozubowski. 相似文献
82.
83.
Technical Physics - Analytical models for the magnetization vector field B m in a uniaxial ferromagnetic film are studied. Some of them are found to closely approximate B m even if the quality... 相似文献
84.
85.
The study of the effect of a perfectly conducting plane placed at a certain distance from the surface of a potassium niobate crystal on the characteristics of the generalized Rayleigh and Gulyaev-Bleustein surface waves is continued. In addition, the effect of an infinitely thin conducting layer applied to the surface of the piezoelectric on the characteristics of these waves is analyzed. It is found that a variation in the conductance of this layer can produce a result that completely differs from the result obtained when a perfectly conducting plane is moved toward the surface, although the extreme states of these actions (electrically open and short-circuited surfaces) are identical. A possible physical explanation of this difference is proposed. 相似文献
86.
O. V. Kirichenko D. Krstovska V. G. Peschansky 《Journal of Experimental and Theoretical Physics》2004,99(1):217-223
Thermoelectric effects are investigated theoretically in layered conductors with a quasi-two-dimensional electron energy spectrum of arbitrary type in a strong magnetic field. It is shown that, at temperatures sufficiently low for quantization of the orbital motion of charge carriers in a magnetic field to be required, there exist giant quantum oscillations of the thermoelectric field. Thermoelectric emf is studied as a f unction of the orientation of the magnetic field with respect to the layers; experimental investigation of this function allows one to determine the velocity distribution of conduction electrons on the Fermi surface. 相似文献
87.
S. A. Sadovsky Yu. V. Kharlov A. L. S. Angelis E. Gładysz-Dziaduś V. L. Korotkikh G. Mavromanolakis A. D. Panagiotou 《Physics of Atomic Nuclei》2004,67(2):396-405
A phenomenological model for describing the production of Centauro events in relativistic heavy-ion collisions is discussed. The model provides quantitative predictions for kinematical variables, for the baryon number, and for the masses of a Centauro fireball and of its decay products. A Centauro fireball decays predominantly into nucleons, strange hyperons, and possibly strangelets. Centauro events in Pb + Pb collisions at the LHC energy are simulated for the CASTOR detector. The signatures of these events are discussed in detail. 相似文献
88.
M. I. Adamovich V. Bradnova S. Vokal S. G. Gerasimov V. A. Dronov P. I. Zarubin A. D. Kovalenko K. A. Kotel'nikov V. A. Krasnov V. G. Larionova F. G. Lepekhin A. I. Malakhov G. I. Orlova N. G. Peresadko N. G. Polukhina P. A. Rukoyatkin V. V. Rusakova N. A. Salmanova B. B. Simonov M. M. Chernyavsky M. Haiduc S. P. Kharlamov L. Just 《Physics of Atomic Nuclei》2004,67(3):514-517
New results concerning the topology of the fragmentation of relativistic nuclei 7Li and 10B are presented. A program is proposed for studying the cluster structure of stable and radioactive nuclei. The use of emulsions in the investigation of nuclear clustering in the fragmentation of light nuclei at energies are in excess of 1 GeV per nucleon is discussed. 相似文献
89.
Peixiang Xing Gilles P. Robertson Michael D. Guiver Serguei D. Mikhailenko Serge Kaliaguine 《Journal of polymer science. Part A, Polymer chemistry》2004,42(12):2866-2876
A series of sulfonated poly(aryl ether ketone)s (SPAEKs) were prepared by aromatic nucleophilic polycondensation of 2,6‐dihydroxynaphthalene with 5,5′‐carbonyl‐bis(2‐fluorobenzenesulfonate) and 4,4′‐difluorobenzophenone. The structure and degree of sulfonation (DS) of the SPAEKs were characterized using 1H NMR spectroscopy. The experimentally observed DS values were close to the expected values derived from the starting material ratios. The thermal stabilities of the SPAEKs were characterized by thermogravimetric analysis, which showed that in acid and sodium salt forms they were thermally stable in air up to about 240 and 380 °C, respectively. Transparent membranes cast from the directly polymerized SPAEKs exhibited good mechanical properties in both dry and hydrated states. The dependence of water uptake and of membrane swelling on the DS at different temperatures was studied. SPAEK membranes with a DS from 0.72 to 1.60 maintained adequate mechanical properties after immersion in water at 80 °C for 24 h. The proton conductivity of SPAEK membranes with different degrees of sulfonation was measured as a function of temperature. The proton conductivity of the SPAEK films increased with increased DS, and the highest room temperature conductivity (4.2 × 10?2 S/cm) was recorded for a SPAEK membrane with a DS of 1.60, which further increased to 1.1 × 10?1 S/cm at 80 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2866–2876, 2004 相似文献
90.
G. Ullrich D. Herzog R. Liska P. Burtscher N. Moszner 《Journal of polymer science. Part A, Polymer chemistry》2004,42(19):4948-4963
Camphorquinone (CQ), a widely used photoinitiator (PI) in dental applications, was covalently bonded to aromatic amines to enhance the rate of electron and proton transfer effect due to the close vicinity of the diketone and the amine group. 10‐bromocamphorquinone and 10‐bromomethylcamphorquinone were selected as suitable precursors for esterification with the carboxyl group containing aromatic amines based on 4‐dimethylaminobenzoic acid. Properties of the new photoinitiating systems were investigated by UV spectroscopy and differential scanning photocalorimetry in lauryl acrylate. Compared to physical mixtures, in all cases similar or even better performance was obtained. Surprisingly, 10‐acetyl derivatives 7 – 9 and 18 especially, were found to be highly reactive. Compared to CQ/ethyl 4‐dimethylaminobenzoate, the rate of photopolymerization was increased by a factor of up to 2. Intramolecular reaction was confirmed by photo‐differential scanning calorimetry experiments with varying PI concentrations. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4948–4963, 2004 相似文献