全文获取类型
收费全文 | 313922篇 |
免费 | 1568篇 |
国内免费 | 738篇 |
专业分类
化学 | 143216篇 |
晶体学 | 4297篇 |
力学 | 18704篇 |
综合类 | 7篇 |
数学 | 59208篇 |
物理学 | 90796篇 |
出版年
2020年 | 2488篇 |
2019年 | 3014篇 |
2018年 | 14613篇 |
2017年 | 14590篇 |
2016年 | 11469篇 |
2015年 | 3407篇 |
2014年 | 5038篇 |
2013年 | 9740篇 |
2012年 | 11311篇 |
2011年 | 19215篇 |
2010年 | 12891篇 |
2009年 | 13451篇 |
2008年 | 14988篇 |
2007年 | 16957篇 |
2006年 | 7899篇 |
2005年 | 8018篇 |
2004年 | 7943篇 |
2003年 | 7844篇 |
2002年 | 7112篇 |
2001年 | 6951篇 |
2000年 | 5248篇 |
1999年 | 3949篇 |
1998年 | 3659篇 |
1997年 | 3398篇 |
1996年 | 3155篇 |
1995年 | 2813篇 |
1994年 | 2700篇 |
1993年 | 2778篇 |
1992年 | 2830篇 |
1991年 | 3164篇 |
1990年 | 3040篇 |
1989年 | 3130篇 |
1988年 | 2930篇 |
1987年 | 2902篇 |
1986年 | 2745篇 |
1985年 | 3374篇 |
1984年 | 3460篇 |
1983年 | 2966篇 |
1982年 | 3062篇 |
1981年 | 2911篇 |
1980年 | 2684篇 |
1979年 | 3027篇 |
1978年 | 3280篇 |
1977年 | 3377篇 |
1976年 | 3369篇 |
1975年 | 3152篇 |
1974年 | 3112篇 |
1973年 | 3263篇 |
1972年 | 2604篇 |
1971年 | 2382篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
101.
A. I. Vinogradov 《Journal of Mathematical Sciences》2007,140(5):646-654
An estimate of the remainder in the spectral decomposition of the generalized ζ function is given, which is more precise than
the known ones. This paper is a continuation of a previous paper published in one of the preceding issues. Bibliography: 1
title.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 330, 2006, pp. 77–92. 相似文献
102.
103.
I. P. Raevskii L. A. Reznichenko M. P. Ivliev V. G. Smotrakov V. V. Eremkin M. A. Malitskaya L. A. Shilkina S. I. Shevtsova A. V. Borodin 《Crystallography Reports》2003,48(3):486-490
(Na, K)NbO3 crystals with a perovskite structure and a KNbO3 content up to 40 mol % were grown from flux with the use of the solvent NaBO2. The dielectric measurements of the crystals grown revealed phase transitions that had never been observed before in ceramic samples. 相似文献
104.
105.
J. Kircher M. Cardona M. Alouani S. Gopalan O. Jepsen O. K. Andersen
E. Kaldis
J. Karpinski S. Rusieki 《Physica C: Superconductivity and its Applications》1992,200(3-4):413-417We report results of ellipsometric measurements of the dielectric tensor of YBa2Cu4O8 as well as calculations employing density functional theory in the local density approximation (LDA). For the computation of the one-electron eigenvalues and states the linear-muffin-tin-orbital method (LMTO) was used. Measured and calculated results show good agreement. In particular, the calculation predicts different band structures for YBa2Cu3O7 and YBa2Cu4O8 in the vicinity of the Fermi energy which lead to significant differences in the optical spectra. One such difference is a region of small ε2 in the near infrared which is a fingerprint of the high (relative to the top of the highest fully occupied band) Fermi energy as compared to the situation in YBa2Cu3O7. Our experimental results confirm the theoretical findings. 相似文献
106.
V. D. Levchenko A. I. Morozov A. S. Sigov 《Journal of Experimental and Theoretical Physics》2002,94(5):985-991
Multilayer ferromagnet-layered antiferromagnet (Fe/Cr) structures frustrated because of roughness of interlayer boundaries were studied by mathematical modeling methods. The phase diagram of a three-layer system (plotted as film thickness versus the degree of roughness of the interfaces) was obtained, and the order parameter distributions in each phase were determined. The character of phase transitions in this system was studied. The applicability range of the Slonczewski magnetic proximity model was determined. 相似文献
107.
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
108.
This Review discusses the synthesis and characterization by our Group of new antibiotics belonging to the class of penicillins, cephalosporins and rifamycins with ferrocenyl and 1, 1′-ferrocenilene residues in the molecule. As reactants for 6-aminopenicillanic acid (6-APA) and 7-aminocephalosporanic acid (7-ACA) the following were used: 1, 1-bis(chlorocarbonyl)ferrocene, ferrocenyl sulfochloride, 1, 1′-ferrocenylenedisulfochloride and thioglycolic acids S-modified with ferrocene. In the synthesis of rifamycins, the hydrazides of the thioglycolic acids, S-modified with ferrocene, were employed as nucleophilic agents. The synthesized intermediates were characterized by elemental analysis, TLC, IR, UV and 1H NMR spectra. The characterization of new antibiotics was made by TLC, IR and UV spectral analysis. Biological activity was tested on Gram-negative and Gram-positive bacteria. Good activity is reported towards Gram-positive bacteria in the case of derivatives containing residues of thioglycolic acid S-modified with ferrocene, the antibacterial activity being similar to that of amoxicillin, carbenicillin and cephalothin. All compounds are inactive towards Gram-negative bacteria. 相似文献
109.
D. A. Rakhimov M. Kh. Malikova A. A. Vakhabov I. O. Ruziev T. R. Abdurakhmanov 《Chemistry of Natural Compounds》1995,31(2):260-261
Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 313–314, March–April, 1995. Original article submitted November 7, 1994. 相似文献
110.
I. A. Semaev 《Mathematical Notes》1991,50(4):1055-1058
Translated from Matematicheskie Zametki, Vol. 50, No. 4, pp. 102–107, October, 1991. 相似文献