全文获取类型
收费全文 | 183463篇 |
免费 | 926篇 |
国内免费 | 293篇 |
专业分类
化学 | 91684篇 |
晶体学 | 2678篇 |
力学 | 9577篇 |
综合类 | 7篇 |
数学 | 21701篇 |
物理学 | 59035篇 |
出版年
2020年 | 1915篇 |
2019年 | 2361篇 |
2018年 | 3499篇 |
2017年 | 3639篇 |
2016年 | 4270篇 |
2015年 | 1902篇 |
2014年 | 3677篇 |
2013年 | 7236篇 |
2012年 | 5668篇 |
2011年 | 6762篇 |
2010年 | 5638篇 |
2009年 | 5794篇 |
2008年 | 6494篇 |
2007年 | 6452篇 |
2006年 | 5716篇 |
2005年 | 5062篇 |
2004年 | 4896篇 |
2003年 | 4455篇 |
2002年 | 4608篇 |
2001年 | 5062篇 |
2000年 | 3738篇 |
1999年 | 2866篇 |
1998年 | 2643篇 |
1997年 | 2502篇 |
1996年 | 2289篇 |
1995年 | 2106篇 |
1994年 | 2070篇 |
1993年 | 2092篇 |
1992年 | 2111篇 |
1991年 | 2438篇 |
1990年 | 2372篇 |
1989年 | 2434篇 |
1988年 | 2304篇 |
1987年 | 2340篇 |
1986年 | 2171篇 |
1985年 | 2714篇 |
1984年 | 2757篇 |
1983年 | 2371篇 |
1982年 | 2431篇 |
1981年 | 2321篇 |
1980年 | 2126篇 |
1979年 | 2468篇 |
1978年 | 2621篇 |
1977年 | 2719篇 |
1976年 | 2814篇 |
1975年 | 2605篇 |
1974年 | 2521篇 |
1973年 | 2698篇 |
1972年 | 2192篇 |
1971年 | 2003篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
981.
T. V. Gubaidulina N. I. Chistyakova V. S. Rusakov 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(9):1269-1272
Natural and synthetic layered iron hydroxysulfides: tochilinite and valleriite, have been investigated by Mössbauer spectroscopy. Tochilinite, magnetite, troilite, and pyrite phases were found in the products of tochilinite synthesis under different conditions. The relative contents of the phases found are determined as functions of the relative magnesium content in the initial mixture. Crystallochemical identification of the 57Fe subspectra of valleriite has been performed. 相似文献
982.
K. Olimov K. G. Gulamov V. V. Lugovoi S. L. Lutpullaev Kh. K. Olimov V. I. Petrov 《Physics of Atomic Nuclei》2007,70(11):1977-1979
983.
An interrogator of Bragg sensors based on a narrow-band tunable erbium laser is developed. The laser characteristics enable one to interrogate up to 45 temperature sensors in a range of 100°C with an error of no greater than 1°C. 相似文献
984.
New results are presented of an experimental investigation of the spectrum of 36P → 37P two-photon microwave transition in Rydberg atoms of sodium in a constant electric field. Depending on the conditions of excitation of the initial 36P state (the constant electric field is switched on either before or after the exciting laser pulse) and polarization of laser radiation, a strong variation is observed of the amplitudes of individual two-photon transitions between the fine-structure Stark components of the 36P and 37P states. This effect is an analog of the Paschen-Back effect in a strong magnetic field and is due to the break of L-S coupling and to the variation of the wave functions of Rydberg electrons in an electric field. It is also found that the break of L-S coupling affects considerably the shape of double Stark resonance arising upon intersection of the virtual intermediate level of two-photon transition with the real intermediate 37S level. 相似文献
985.
V. B. Sokolov A. N. Chekhlov T. A. Epishina I. V. Martynov 《Russian Chemical Bulletin》1992,41(2):236-240
The O-(arylcarbamoyl)butyrhydroximoyl chlorides were synthesized, and the x-ray structural analysis (XSA) of one of them — O-(o-tolylcarbamoyl)butyrhydroximoyl chloride — was performed. It was established from the data of the XSA and the PMR spectra that all synthesized compounds are the Z isomers.Institute of Physiologically Active Substances, Russian Academy of Sciences, 142432 Chernogolovka. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 315–319, February, 1992. 相似文献
986.
The emission characteristics of a transverse volume discharge in a He: HCl = 10: 1 mixture at a total pressure of 1–8 kPa were investigated. The plasma volume was 18 × 2.2 × 1 cm3, the interelectrode distance was d=2.2 cm, and the charging voltage of the main storage capacitor was 5–10 kV. The emission characteristics of the discharge were studied in the spectral range of 500–1000 nm. This type of discharge can be used in pulsed dry-etching plasmochemical reactors. The density of atomic chlorine radicals in the plasma was optimized in terms of the pressure of the initial working He-HCl mixture by measuring the relative radiation intensity of the Cl 837(5)-nm spectral line. The density of molecular radicals can be monitored indirectly by recording radiation from the excited chlorine-free decomposition products of HCl molecules (the Hα 656-nm line). 相似文献
987.
V. N. Esenin A. A. Stepanov L. I. Denisovich 《Russian Journal of Applied Chemistry》2006,79(12):1957-1963
Electrochemical procedure for express evaluation of the corrosion effect of aqueous glycol solutions on the metallic construction materials for cooling systems was studied. This procedure was used to develop new coolant formulations. 相似文献
988.
Crystallization of Ca(HCOO)2 from aqueous solutions was studied and conditions under which an ultrapure product can be obtained were determined. 相似文献
989.
We have studied hydrogen adsorption on the Ge(1 1 1) c(2 × 8) surface using scanning tunneling microscopy (STM) and angle-resolved photoelectron spectroscopy (ARPES). We find that atomic hydrogen preferentially adsorbs on rest atom sites. The neighbouring adatoms appear higher in STM images, which clearly indicates a charge transfer from the rest atom states to the adatom states. The surface states near the Fermi-level have been followed by ARPES as function of H exposure. Initially, there is strong emission from the rest atom states but no emission at the Fermi-level which confirms the semiconducting character of the c(2 × 8) surface. With increasing H exposure a structure develops in the close vicinity of the Fermi-level. The energy position clearly indicates a metallic character of the H-adsorbed surface. Since the only change in the STM images is the increased brightness of the adatoms neighbouring a H-terminated rest atom, we identify the emission at the Fermi-level with these adatom states. 相似文献
990.
D. Chiladze J. Carbonell S. Dymov V. Glagolev M. Hartmann V. Hejny A. Kacharava I. Keshelashvili A. Khoukaz H.R. Koch V. Komarov P. Kulessa A. Kulikov G. Macharashvili Y. Maeda T. Mersmann S. Merzliakov S. Mikirtytchiants A. Mussgiller M. Nioradze H. Ohm F. Rathmann R. Schleichert H.J. Stein H. Ströher Yu. Uzikov S. Yaschenko C. Wilkin 《Physics letters. [Part B]》2006