全文获取类型
收费全文 | 473096篇 |
免费 | 5329篇 |
国内免费 | 1583篇 |
专业分类
化学 | 255688篇 |
晶体学 | 6740篇 |
力学 | 21253篇 |
综合类 | 15篇 |
数学 | 53438篇 |
物理学 | 142874篇 |
出版年
2021年 | 3316篇 |
2020年 | 3686篇 |
2019年 | 3998篇 |
2018年 | 4904篇 |
2017年 | 4793篇 |
2016年 | 7687篇 |
2015年 | 5173篇 |
2014年 | 7680篇 |
2013年 | 20764篇 |
2012年 | 16113篇 |
2011年 | 19865篇 |
2010年 | 13316篇 |
2009年 | 13323篇 |
2008年 | 18149篇 |
2007年 | 18242篇 |
2006年 | 17390篇 |
2005年 | 15798篇 |
2004年 | 14452篇 |
2003年 | 12688篇 |
2002年 | 12430篇 |
2001年 | 13977篇 |
2000年 | 10773篇 |
1999年 | 8408篇 |
1998年 | 6854篇 |
1997年 | 6888篇 |
1996年 | 6455篇 |
1995年 | 5958篇 |
1994年 | 5645篇 |
1993年 | 5402篇 |
1992年 | 6110篇 |
1991年 | 6189篇 |
1990年 | 5703篇 |
1989年 | 5589篇 |
1988年 | 5630篇 |
1987年 | 5549篇 |
1986年 | 5201篇 |
1985年 | 7173篇 |
1984年 | 7436篇 |
1983年 | 6001篇 |
1982年 | 6507篇 |
1981年 | 6244篇 |
1980年 | 6244篇 |
1979年 | 6361篇 |
1978年 | 7187篇 |
1977年 | 6856篇 |
1976年 | 6519篇 |
1975年 | 6122篇 |
1974年 | 6067篇 |
1973年 | 6234篇 |
1972年 | 4039篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
V. O. Kur'yanov T. F. Zhelobetskaya A. E. Zemlyakov V. Ya. Chirva 《Chemistry of Natural Compounds》1993,29(1):103-106
The synthesis has been effected of derivatives of MDP having a spacer with an amino or carboxy group. The final stage of the synthesis was the condensation of Boc-L-Ala-D-iGln with 6-aminohexanol (followed by the two-stage replacement of the hydroxy by an azido group) or with benzyl 6-aminohexanoate.Simferopol' State University. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 122–125, January–February, 1993. 相似文献
992.
Published in Teoreticheskaya i Matematicheskaya Fizika, Vol. 95, No. 2, pp. 183–186, May, 1993. 相似文献
993.
Modeling and numerical simulations of the convective flows induced by the vibration of the monocrystal during crystal growth have been performed for two configurations simulating the Cz and FZ methods. This permitted to emphasize the role of different vibrational mechanisms in the formation of the average flows. It is shown that an appropriate combination of these mechanisms can be used to counteract the usual convective flows (buoyancy- and/or thermocapillary-driven) inherent to crystal growth processes from the liquid phase. While vibrational convection is rather complex due to these identified mechanisms, the new modeling used in the present paper opens up very promising perspectives to efficiently control heat and mass transfer during real industrial applications of crystal growth from the liquid phase. 相似文献
994.
995.
996.
997.
D. I. Zhukhovitskii 《Journal of Experimental and Theoretical Physics》2002,94(2):336-344
Numerical experiments showed that the number-of-bonds distribution of particles that form a fairly large molten argon-like cluster was bimodal. This result was interpreted as a consequence of the formation of two “phases, ” namely, particles inside the cluster and a monolayer of particles lying above the others. Particle chains were shown to be formed near the surface of the cluster. Splitting off of separate particles from them was the most probable mechanism of vaporization. Model concepts that described the dependences observed in numerical experiments were developed. 相似文献
998.
B. Pignataro L. Chi S. Gao B. Anczykowski C. Niemeyer M. Adler H. Fuchs 《Applied Physics A: Materials Science & Processing》2002,74(3):447-452
Self-assembled oligomeric nanostructures consisting of bisbiotinylated DNA fragments connected by the protein streptavidin
(STV) are studied by dynamic scanning force microscopy (SFM) operating in air. A comparison of the images taken in repulsive
and attractive regimes is systematically made on DNA and STV structures. Stable and reproducible SFM images are obtained in
the attractive regime by using a special feedback circuit, called Q-control. On the other hand, when SFM is operating in the
repulsive regime, deformation of the structures that reduce the resolution and the image quality are clearly observable. The
heights of both DNA and STV have been measured as a function of the tip/molecule interaction forces. This study offers the
possibility to suggest a different mechanical behavior of DNA with respect to STV.
Received: 24 July 2001 / Accepted: 3 December 2001 / Published online: 4 March 2002 相似文献
999.
R. Gerbaldo G. Ghigo G. Giunchi L. Gozzelino F. Laviano E. Mezzetti 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(3):297-300
We present results from an extended magneto-optical (MO) analysis of two samples cut from high-density pellets of MgB2. The first sample was studied in order to show that no matter how large the sample is and despite the bulk granularity, the
material enters into a critical state in a crystal-like fashion. The second sample was chosen for the quantitative analysis.
A numerical approach based on an inverted 2D Biot-Savart model was used to calculate the current paths across the homogeneous
polycrystalline bulk, as well as in the vicinity and across some morphological defects. Local current densities in the homogeneous
part were estimated as a function of the applied magnetic field at different temperatures, in three regimes: below full penetration,
at full penetration and above full penetration, respectively. A hypothesis of interpretation of the apparent absence of magnetic
granularity inside the polycrystalline microstructure is presented. It is related to a critical state likely reached by a
network of strongly coupled Josephson junctions.
Received 31 May 2001 and Received in final form 5 December 2001 相似文献
1000.