全文获取类型
收费全文 | 137909篇 |
免费 | 11046篇 |
国内免费 | 8340篇 |
专业分类
化学 | 69474篇 |
晶体学 | 1566篇 |
力学 | 6770篇 |
综合类 | 498篇 |
数学 | 13838篇 |
物理学 | 41072篇 |
无线电 | 24077篇 |
出版年
2023年 | 1841篇 |
2022年 | 2697篇 |
2021年 | 3597篇 |
2020年 | 3694篇 |
2019年 | 3831篇 |
2018年 | 4070篇 |
2017年 | 4060篇 |
2016年 | 5041篇 |
2015年 | 4097篇 |
2014年 | 5572篇 |
2013年 | 7423篇 |
2012年 | 8102篇 |
2011年 | 8317篇 |
2010年 | 6459篇 |
2009年 | 6541篇 |
2008年 | 6980篇 |
2007年 | 6538篇 |
2006年 | 6055篇 |
2005年 | 5357篇 |
2004年 | 4397篇 |
2003年 | 4061篇 |
2002年 | 4016篇 |
2001年 | 3541篇 |
2000年 | 2916篇 |
1999年 | 2531篇 |
1998年 | 2273篇 |
1997年 | 2037篇 |
1996年 | 1903篇 |
1995年 | 1600篇 |
1994年 | 1640篇 |
1993年 | 1481篇 |
1992年 | 1408篇 |
1991年 | 1416篇 |
1990年 | 1364篇 |
1989年 | 1200篇 |
1988年 | 1028篇 |
1987年 | 1025篇 |
1986年 | 956篇 |
1985年 | 979篇 |
1984年 | 970篇 |
1983年 | 855篇 |
1982年 | 831篇 |
1979年 | 808篇 |
1978年 | 815篇 |
1977年 | 814篇 |
1976年 | 921篇 |
1975年 | 817篇 |
1974年 | 846篇 |
1973年 | 848篇 |
1972年 | 755篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Yu V Sharvin 《Pramana》1987,28(5):592-592
Investigation of the galvanomagnetic properties of disordered metals in weak magnetic fields [r(H)?l, wherer(H) is the electron trajectory radius andl, the electron free path], proved to be one of the effective experimental methods of studying disordered metals. The phase difference between the interfering electron waves is affected by the presence of magnetic flux in the sample. One of the observable effects is the oscillatory magnetoresistanceK(H) of multiconnected samples predicted by Altshuleret al (1981). The period ofK(H) oscillations for the hollow cylinders, networks or chains with orifices cross-sections areasS isΔH=φ 0/2S [whereφ 0=hc/e]. The amplitude and the phase of the oscillations depend on the spin orbit interaction, the intensity of superconductive fluctuation etc. It should be noted that in small “mesoscopic” single loops the oscillations with the periodΔH?φ 0/S were also observed recently (see also Altshuleret al 1987 included in this issue). 相似文献
102.
103.
We demonstrate a method that permits to obtain generalized solutions for some quasilinear equations and systems of hyperbolic
type. The corresponding variational principle is constructed using the theory of equilibrium of a potential in an external
field.
Dedicated to the memory of B. M. Levitan
Supported by RFBR grants Nos. 05-01-00522 and NSh-1551.2003.1, by Program No. 1 of the Branch of Mathematics, Russian Academy
of Sciences, and by INTAS project No. 03-51-6637. 相似文献
104.
105.
V. Yu. Belashov 《Radiophysics and Quantum Electronics》2002,45(5):376-380
We consider generalizations of the earlier results, obtained for one-dimensional equations of the Kadomtsev–Petviashvili (KP) class, to two- and three-dimensional KP-class equations with an arbitrary nonlinearity index with allowance for the higher-order dispersion correction and terms describing dissipation and instability. The asymptotics of soliton and nonsoliton solutions are derived. Constructing phase portraits in the 8-dimensional space based on the results of a qualitative analysis of generalized Korteweg–de Vries (KdV) equations is discussed. 相似文献
106.
禹思敏 《电气电子教学学报》2002,24(2):29-32
对数字通信中MPSK系统的调制与解调问题进行了较为的分析,并以8PSK和循环码16PSK系统为例,阐述其调制器电路的逻辑设计方法。在此基础上给出了8PSK系统调制与解调的一种方案,讨论了循环码和自然二进制码16PSK系统的调制器的具体设计过程,该设计方法可应用于一般MPSK系统的逻辑设计。 相似文献
107.
A. I. Magunov A. Ya. Faenov I. Yu. Skobelev T. A. Pikuz E. Biémont P. Quinet F. Blasco C. Bonte F. Dorchies T. Caillaud F. Salin C. Stenz 《Journal of Experimental and Theoretical Physics》2002,95(6):998-1005
The satellite structure of 1s2p 1,3 P 1-1s 21 S 0 lines of the He-like argon ion in plasma produced by a 45-fs laser pulse in a gas-jet cluster target is measured with a high spectral resolution. Radiation transitions 2p → 1s from autoionizing states (AISs) are detected for ions ranging from Li-like to F-like. The spectrum observed is theoretically simulated with the use of the spectroscopic data for the AISs of multicharged ions obtained within the multiconfiguration relativistic Hartree-Fock method. Good agreement with experimental data is obtained when the main population channels of these states are taken into account for typical values of cluster-target plasma parameters. 相似文献
108.
An overview of theoretical and experimental studies of the coherent type-B e
+
e-pair production by photons in aligned crystals performed at Nuclear Physics Institute at Tomsk Polytechnic University is given. 相似文献
109.
M. A. Augustyniak-Jabłokow K. Łukaszewicz A. Pietraszko V. E. Petrashen Yu. V. Yablokov 《Physics of the Solid State》2002,44(8):1480-1483
The EPR spectra evolution of Cs2Zn1?x Cux(ZrF6)2 · 6H2O (x=0.01, 0.6, 0.8, and 1.0) in the temperature range 4.2–330 K and the x-ray structure analysis of the compound with x=1.0 in the range 150–327 K show that the Jahn-Teller (JT) complex Cu(H2O)6 coordination sphere undergoes a plastic deformation. The observed effect is due to the combined influence of small lattice strains existing in the paraphase and a new one appearing as a result of a ferroelastic phase transition and increasing with decreasing temperature below T c . It is proved that both cooperative interactions between JT complexes and ferroelastic strain stabilize a certain JT configuration. The problem of instability of a JT configuration compressed at T ~ 265 K is discussed. 相似文献
110.
Discharges with liquid nonmetallic electrodes of much interest for applications are investigated. It is found that a dc discharge between two streams of tap water in air at atmospheric pressure is stable at a currentof 40≤I≤100 mA. The discharge exists in the diffuse (volume) form with a relatively low current density (∼0.2 A/cm2) and a high (above one kilovolt) voltage drop across the air gap (∼1 cm) between the water electrodes. The current density and voltage depend only slightly on the discharge current. Probe measurements show that three regions can be distinguished in the discharge: two electrode regions (1–2 mm in length) and a discharge column with a constant electric field of ≈0.8 kV/cm (i.e., E/N≈20 Td, because the gas in the discharge is heated up to 1500–2000 K). The average electric field strength near the electrodes is E≈2–3×103 V/cm (E/N≈60–80 Td). The charged particle density in the column is n ∼ 1012 cm−3. The probe measurements of n agree with the previous microwave absorption measurements. The water vapor concentration in the column is also estimated from probe measurements. 相似文献