全文获取类型
收费全文 | 435451篇 |
免费 | 5503篇 |
国内免费 | 1230篇 |
专业分类
化学 | 233785篇 |
晶体学 | 6489篇 |
力学 | 18765篇 |
综合类 | 13篇 |
数学 | 49929篇 |
物理学 | 133203篇 |
出版年
2021年 | 3763篇 |
2020年 | 4186篇 |
2019年 | 4519篇 |
2018年 | 5853篇 |
2017年 | 5744篇 |
2016年 | 8831篇 |
2015年 | 5564篇 |
2014年 | 8543篇 |
2013年 | 20187篇 |
2012年 | 15650篇 |
2011年 | 19263篇 |
2010年 | 13499篇 |
2009年 | 13354篇 |
2008年 | 17650篇 |
2007年 | 17543篇 |
2006年 | 16253篇 |
2005年 | 14552篇 |
2004年 | 13524篇 |
2003年 | 11892篇 |
2002年 | 11729篇 |
2001年 | 13429篇 |
2000年 | 10086篇 |
1999年 | 7917篇 |
1998年 | 6569篇 |
1997年 | 6314篇 |
1996年 | 6081篇 |
1995年 | 5470篇 |
1994年 | 5392篇 |
1993年 | 5197篇 |
1992年 | 5828篇 |
1991年 | 5925篇 |
1990年 | 5664篇 |
1989年 | 5473篇 |
1988年 | 5494篇 |
1987年 | 5375篇 |
1986年 | 5091篇 |
1985年 | 6562篇 |
1984年 | 6695篇 |
1983年 | 5306篇 |
1982年 | 5388篇 |
1981年 | 5369篇 |
1980年 | 4955篇 |
1979年 | 5355篇 |
1978年 | 5491篇 |
1977年 | 5386篇 |
1976年 | 5330篇 |
1975年 | 4918篇 |
1974年 | 4887篇 |
1973年 | 4881篇 |
1972年 | 3455篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
Mathematical Notes - 相似文献
982.
Chi-Kwong Li Ilya M. Spitkovsky 《Journal of Mathematical Analysis and Applications》2003,282(1):329-340
Existence of the fractional powers is established in Banach algebra setting, in terms of the numerical ranges of elements involved. The behavior of the spectra and (for Hermitian ∗-algebras satisfying some additional hypotheses) the ∗-numerical range under taking these powers also is investigated. 相似文献
983.
A simple procedure for the synthesis of an important standard, isotopically enriched methylmercury, which is not commercially available, has been established successfully. The isotopically enriched standard synthesized is utilized in conventional isotope dilution mass spectrometry (IDMS), as well as in speciated IDMS (SIDMS), for determination of the true concentration of methylmercury in environmental samples. The CH3201Hg+ standard has been synthesized from commercially available 201HgO and tetramethyltin. The synthesis time required is 1 h at 60°C. The product is highly pure, yielding more than 90% as 201Hg in CH3201Hg+. Hazardous dimethylmercury does not occur during this synthesis procedure. The product synthesized was analyzed using high‐performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (ICP‐MS) and ICP‐MS alone in order to determine its concentration, isotopic composition and purity. The stability of the product was also evaluated for over 6 months and found to be stable at 4°C in the dark. The isotopically enriched methylmercury synthesized can be used in SIDMS and IDMS analyses as a standard. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
984.
I. L. Bataronov A. M. Roshchupkin 《Journal of Applied Mechanics and Technical Physics》1991,32(2):259-265
Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 2, pp. 127–134, March–April, 1991. 相似文献
985.
986.
987.
M.K. Gupta Vijay Gupta Manoj Kumar 《Journal of Mathematical Analysis and Applications》2007,330(2):799-816
In the present paper we introduce a new family of linear positive operators and study some direct and inverse results in simultaneous approximation. 相似文献
988.
989.
M. I. Kurkin 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(11):1607-1609
The conditions of compatibility of the magnetic sublattice hypothesis with the requirements of quantum theory have been derived. These conditions imply the presence of (even weak) magnetic anisotropy and a macroscopic number of spins in the sublattice. 相似文献
990.