全文获取类型
收费全文 | 339024篇 |
免费 | 3367篇 |
国内免费 | 993篇 |
专业分类
化学 | 171468篇 |
晶体学 | 5444篇 |
力学 | 15723篇 |
综合类 | 7篇 |
数学 | 39724篇 |
物理学 | 111018篇 |
出版年
2021年 | 3239篇 |
2020年 | 3506篇 |
2019年 | 3907篇 |
2018年 | 5307篇 |
2017年 | 5545篇 |
2016年 | 7601篇 |
2015年 | 4352篇 |
2014年 | 7278篇 |
2013年 | 16343篇 |
2012年 | 13027篇 |
2011年 | 15625篇 |
2010年 | 11396篇 |
2009年 | 11167篇 |
2008年 | 13815篇 |
2007年 | 13818篇 |
2006年 | 12797篇 |
2005年 | 11173篇 |
2004年 | 10340篇 |
2003年 | 9121篇 |
2002年 | 9046篇 |
2001年 | 10497篇 |
2000年 | 7748篇 |
1999年 | 6053篇 |
1998年 | 5054篇 |
1997年 | 4898篇 |
1996年 | 4594篇 |
1995年 | 3943篇 |
1994年 | 3899篇 |
1993年 | 3766篇 |
1992年 | 4154篇 |
1991年 | 4368篇 |
1990年 | 4145篇 |
1989年 | 4035篇 |
1988年 | 3818篇 |
1987年 | 3947篇 |
1986年 | 3705篇 |
1985年 | 4698篇 |
1984年 | 4723篇 |
1983年 | 3916篇 |
1982年 | 4023篇 |
1981年 | 3748篇 |
1980年 | 3689篇 |
1979年 | 3951篇 |
1978年 | 3938篇 |
1977年 | 3940篇 |
1976年 | 3907篇 |
1975年 | 3706篇 |
1974年 | 3635篇 |
1973年 | 3667篇 |
1972年 | 2609篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
In this paper, the NO-to-NO
2
conversion in various gaseous mixtures is experimentally investigated. Streamer coronas are produced with a dc-superimposed high-frequency ac power supply (10–60 kHz). According to NO
x
removal experiments in N
2
+NO
x
and N
2
+O
2
+NO
x
gaseous mixtures, it is supposed that the reverse reaction NO
2
+ONO+O
2
may not only limit NO
2
production in N
2
+NO
x
mixtures, but also increase the energy cost for NO removal. Oxygen could significantly suppress reduction reactions and enhance oxidation processes. The reduction reactions, such as N+NON
2
+O, induce negligible NO removal provided the O
2
concentration is larger than 3.6%. With adding H
2
O into the reactor, the produced NO
2
per unit removed NO can be significantly reduced due to NO
2
oxidation. NH
3
injection could also significantly decrease the produced NO
2
via NH and NH
2
- related reduction reactions. Almost 100% of NO
2
can be removed in gaseous mixtures of N
2
+O
2
+H
2
O+NO
2
with negligible NO production. 相似文献
992.
993.
R. G. Mirskov S. V. Basenko V. Yu. Vitkovskii I. A. Gebel' N. K. Yarosh M. G. Voronkov 《Russian Chemical Bulletin》1989,38(3):597-600
Conclusions Alkoxychlorosilanes react with trimethylacyloxysilanes to give the difficultly accessible alkoxy(acyloxy)silanes of general formula (RO)nSi(OCOR)4-n (n=1–3) in 60–80% yields.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 671–674, March, 1989. 相似文献
994.
995.
996.
997.
Conclusions A convenient method of preparing organochlorohydridesilanes by selective chlorination of organohydridesilanes with stannic chloride was proposed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2114–2117, September, 1967. 相似文献
998.
Podberezskaya N. V. Batsanova L. R. Egorova L. S. 《Journal of Structural Chemistry》1965,6(6):815-818
Journal of Structural Chemistry - 相似文献
999.
Evolution of Statistical Ensembles of Microdomains on the Surface of Films of Rigid-Chain Polyimide during Thermal Imidization 总被引:1,自引:0,他引:1
Bronnikov S. V. Sukhanova T. E. Goikhman M. Ya. 《Russian Journal of Applied Chemistry》2003,76(6):967-971
Statistical ensembles of microdomains formed on the surface of polyimide films based on pyromellitic dianhydride and 2,7-diaminofluorene during thermal imidization were described in terms of the model of reversible aggregation using the electron-microscopic data. Parameters of the statistical distribution were determined for each ensemble depending on the film heating temperature. 相似文献
1000.
Kopeikin V. V. Valueva S. V. Kipper A. I. Filippov A. P. Khlebosolova E. N. Borovikova L. N. Lavrent'ev V. K. 《Russian Journal of Applied Chemistry》2003,76(5):818-821
The nanostructures formed by reduction of Se(IV) in the selenite-ascorbate redox system in an aqueous solution of supermacromolecular polycation, poly[trimethyl(methacryloyloxyethyl)ammonium] methyl sulfate, were studied by static and dynamic optical scattering and flow birefringence. 相似文献