全文获取类型
收费全文 | 429423篇 |
免费 | 2774篇 |
国内免费 | 800篇 |
专业分类
化学 | 205109篇 |
晶体学 | 6851篇 |
力学 | 22660篇 |
综合类 | 6篇 |
数学 | 58812篇 |
物理学 | 139559篇 |
出版年
2021年 | 3932篇 |
2020年 | 4367篇 |
2019年 | 5225篇 |
2018年 | 7436篇 |
2017年 | 7713篇 |
2016年 | 10144篇 |
2015年 | 4984篇 |
2014年 | 9062篇 |
2013年 | 18213篇 |
2012年 | 14548篇 |
2011年 | 17049篇 |
2010年 | 13608篇 |
2009年 | 13834篇 |
2008年 | 16339篇 |
2007年 | 16045篇 |
2006年 | 14627篇 |
2005年 | 12806篇 |
2004年 | 12199篇 |
2003年 | 11235篇 |
2002年 | 11289篇 |
2001年 | 11704篇 |
2000年 | 9137篇 |
1999年 | 6873篇 |
1998年 | 6200篇 |
1997年 | 5990篇 |
1996年 | 5505篇 |
1995年 | 5046篇 |
1994年 | 5047篇 |
1993年 | 4929篇 |
1992年 | 5203篇 |
1991年 | 5523篇 |
1990年 | 5471篇 |
1989年 | 5391篇 |
1988年 | 5168篇 |
1987年 | 5247篇 |
1986年 | 4863篇 |
1985年 | 5923篇 |
1984年 | 6208篇 |
1983年 | 5412篇 |
1982年 | 5631篇 |
1981年 | 5223篇 |
1980年 | 4940篇 |
1979年 | 5525篇 |
1978年 | 5629篇 |
1977年 | 5709篇 |
1976年 | 5864篇 |
1975年 | 5526篇 |
1974年 | 5372篇 |
1973年 | 5698篇 |
1972年 | 4436篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
901.
The complete symmetry algebras of the Veselov-Novikov equation and of the modified Kadomtsev-Petviashvili equation are constructed. Some related questions are discussed.P. P. Shirshov Institute of Oceanology, Russian Academy of Sciences. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 95, No. 1, pp. 34–41, April, 1993. 相似文献
902.
903.
904.
905.
B. D. Symeopoulos P. G. Koutsoukos 《Journal of Radioanalytical and Nuclear Chemistry》1993,173(1):23-36
The formation of barium sulfate in aqueous media causes problems of insoluble scale formation. On the other hand, the coprecipitation of uranium and transuranium elements with barium sulfate has been suggested for the determination of these elements in environmental monitoring processes. Therefore, the study of barium sulfate crystal growth is required. The investigations done so far suffer from the low sensitivity of the analytical methods used. In the present work we have overcome this problem by using131Ba for the preparation of supersaturated solutions. Thus kinetics parameters such as induction time and precipitation rates were measured. The polynuclear mechanism was found to be operative at high and the spiral growth at low supersaturations. 相似文献
906.
Weak-signal methods are used to study long-term changes in the electrophysical and photoelectric properties of Si-SiO2 systems of n- and p-type semiconductors after the action of a steady magnetic field of 102 Oe. It is found that the field electrode can produce regions characterized by the anomalous recombination, migration, and
transformation of nonequilibrium charge carriers, leading to a quasi-oscillating change in the recombination activity of the
semiconducting system. It is observed that the magnetically induced changes in the system depend on the impurity of composition
of the semiconductor. The results obtained are attributed to the decomposition of the growth structures of complexes and subsequent
clustering of the decomposition products at elastic stress sinks.
Tomsk State Academy of Control Systems and Electronics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No.
2, pp. 62–66, February, 1997. 相似文献
907.
Triorganotin(IV) and triorganolead(IV) derivatives of the types Me3Sn(SCZ) and Ph3Pb(SCZ) (where SCZ? is the anion of a semicarbanzone ligand) have been synthesized by substitution reactions of trimethyltin chloride and triphenyl-lead chloride with semicarbazones derived from heterocyclic ketones. The resulting complexes have been characterized by elemental analyses, molecualr weight determinations and conductivity measurements. The mode of bonding has been established on the basis of infrared and 1H, 13C and 119Sn NMR spectroscopic studies. Some respresentative complexes have also been evaluated for their antimicrobial effects on different species of pathogenic fungi and bacteria; the results of these investigations have been reported in the present paper. 相似文献
908.
V. S. Zayachkivs'kii 《Journal of Mathematical Sciences》1993,66(6):2552-2555
We study the variety of divisors of a polynomial operator bundle and the action of the natural symmetry group on it—the group of invertible operators that commute with the linearizer of the bundle. It is established that the orbits can be parametrized by standard Young tableaux whose form and weight depend on the spectral parameters of the bundle and its divisors. We consider the question of existence of factorizations with prescribed spectral characteristics. The correspondence is given in terms of the Littlewood-Richardson combinatorial rule.Translated fromMatematicheskie Metody i Fiziko-Mekhanicheskie Polya, Issue 34, 1991, pp. 8–12. 相似文献
909.
910.