全文获取类型
收费全文 | 95007篇 |
免费 | 3449篇 |
国内免费 | 2466篇 |
专业分类
化学 | 36490篇 |
晶体学 | 961篇 |
力学 | 7676篇 |
综合类 | 104篇 |
数学 | 33597篇 |
物理学 | 22094篇 |
出版年
2024年 | 79篇 |
2023年 | 414篇 |
2022年 | 661篇 |
2021年 | 752篇 |
2020年 | 752篇 |
2019年 | 752篇 |
2018年 | 10946篇 |
2017年 | 10692篇 |
2016年 | 6874篇 |
2015年 | 1696篇 |
2014年 | 1319篇 |
2013年 | 1609篇 |
2012年 | 5343篇 |
2011年 | 11901篇 |
2010年 | 6627篇 |
2009年 | 6954篇 |
2008年 | 7615篇 |
2007年 | 9693篇 |
2006年 | 1137篇 |
2005年 | 2122篇 |
2004年 | 2103篇 |
2003年 | 2461篇 |
2002年 | 1506篇 |
2001年 | 635篇 |
2000年 | 642篇 |
1999年 | 574篇 |
1998年 | 533篇 |
1997年 | 479篇 |
1996年 | 514篇 |
1995年 | 388篇 |
1994年 | 301篇 |
1993年 | 292篇 |
1992年 | 210篇 |
1991年 | 197篇 |
1990年 | 206篇 |
1989年 | 169篇 |
1988年 | 134篇 |
1987年 | 111篇 |
1986年 | 116篇 |
1985年 | 105篇 |
1984年 | 73篇 |
1983年 | 66篇 |
1982年 | 71篇 |
1981年 | 57篇 |
1980年 | 56篇 |
1979年 | 47篇 |
1914年 | 45篇 |
1912年 | 40篇 |
1909年 | 42篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
331.
Oleg Safronov 《Arkiv f?r Matematik》2004,42(2):363-377
We study the spectral properties of Jacobi matrices. By combining Killip's technique [12] with the technique of Killip and
Simon [13] we obtain a result relating the properties of the elements of Jacobi matrices and the corresponding spectral measures.
This theorem is a natural extension of a recent result of Laptev-Naboko-Safronov [17].
The author thanks Sergei Naboko for useful discussions and Barry Simon for pointing out the conjecture. 相似文献
332.
On the characterisation of paired monotone metrics 总被引:1,自引:1,他引:0
Paolo Gibilisco Tommaso Isola 《Annals of the Institute of Statistical Mathematics》2004,56(2):369-381
Hasegawa and Petz introduced the notion of paired monotone metrics. They also gave a characterisation theorem showing that
Wigner-Yanase-Dyson metrics are the only members of the paired family. In this paper we show that the characterisation theorem
holds true under hypotheses that are more general than those used in the above quoted references. 相似文献
333.
334.
Let A be a Weil algebra. The bijection between all natural operators lifting vector fields from m-manifolds to the bundle functor K
A
of Weil contact elements and the subalgebra of fixed elements SA of the Weil algebra A is determined and the bijection between all natural affinors on K
A
and SA is deduced. Furthermore, the rigidity of the functor K
A
is proved. Requisite results about the structure of SA are obtained by a purely algebraic approach, namely the existence of nontrivial SA is discussed. 相似文献
335.
Influence of Turbid Medium Parameters on Back Scattered Intensity and Pulsewidth of Picosecond Pulse
In this paper, we simulate a practical in vivo technique in which is produced influence of turbid medium parameters on backscattered intensity and pulsewidth of picosecond for turbid tissue surface of a semiinfinite medium by a small narrow linewidth laser beams. It is shown that the interaction of the ultra short pulse and the turbid tissue is very used as researching the optical parameters of the turbid medium. 相似文献
336.
Richard P. Stanley 《Israel Journal of Mathematics》2004,143(1):317-339
We survey three recent developments in algebraic combinatorics. The first is the theory of cluster algebras and the Laurent
phenomenon of Sergey Fomin and Andrei Zelevinsky. The second is the construction of toric Schur functions and their application
to computing three-point Gromov-Witten invariants, by Alexander Postnikov. The third development is the construction of intersection
cohomology for nonrational fans by Paul Bressler and Valery Lunts and its application by Kalle Karu to the torich-vector of a nonrational polytope. We also briefly discuss the “half hard Lefschetz theorem” of Ed Swartz and its application
to matroid complexes.
Partially supported by NSF grant #DMS-9988459. 相似文献
337.
Mieko Tanaka-Yamawaki 《Annals of the Institute of Statistical Mathematics》2003,55(2):437-446
Contrary to the common sense in economics and financial engineering, price fluctuations at very fine level of motion exhibit
various evidences against the efficient market hypothesis. We attempt to investigate this issue by studying extensive amount
of foreign currency exchange data for over five years at the finest level of resolution. We specifically focus on the proposed
stability in binomial conditional probabilities originally found in much smaller examples of financial time series. In order
to handle very large data, we have written an efficient program in C that automatically generates those conditional probabilities.
It is found that the stability is maintained for extremely large time duration that covers almost the entire period. Based
on the length of conditions for which the conditional probabilities are distinguishable each other, we identify the length
of memory being less than 3 movements. 相似文献
338.
All homothetic self-similar solutions of the Brans-Dicke scalar field in three-dimensional spacetime with circular symmetry
are found in closed form. 相似文献
339.
Fabio Scardigli 《Foundations of Physics》2007,37(8):1278-1295
The Titius–Bode law for planetary distances is reviewed. A model describing the basic features of this rule in the “quantum-like”
language of a wave equation is proposed. Some considerations about the ’t Hooft idea on the quantum behavior of deterministic
systems with dissipation are discussed. 相似文献
340.
The crystallization behavior of miscible syndiotactic polystyrene (sPS) and atactic polystyrene (aPS) blends with different sPS/aPS weight ratios was investigated in supercritical CO2 by using Fourier‐transform infrared spectroscopy, differential scanning calorimetry, and wide‐angle X‐ray diffraction. Supercritical CO2 and aPS exhibited different effects on the conformational change of sPS and competed with each other. Increasing the content of amorphous aPS in the blends made its effect on the conformational change of sPS gradually surpass that of supercritical CO2. Supercritical CO2 favored the formation of the helical conformation of sPS in lower temperature range and the all trans planar conformation in higher temperature range, instead of forming the latter one only in higher temperature range in ambient atmosphere. However, increasing aPS content in the blends pushed the range for forming the helical conformation to lower temperature and made the all trans planar conformation dominant in aPS/sPS 25/75 blend after treating in supercritical CO2 above 60 °C. The all trans planar zigzag conformation was more favorable than the helical conformation after mixing aPS in sPS in supercritical CO2. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1755–1764, 2007 相似文献