全文获取类型
收费全文 | 14678篇 |
免费 | 596篇 |
国内免费 | 4篇 |
专业分类
化学 | 8156篇 |
晶体学 | 46篇 |
力学 | 268篇 |
数学 | 2008篇 |
物理学 | 4800篇 |
出版年
2023年 | 115篇 |
2021年 | 126篇 |
2020年 | 187篇 |
2019年 | 119篇 |
2018年 | 161篇 |
2017年 | 160篇 |
2016年 | 376篇 |
2015年 | 354篇 |
2014年 | 338篇 |
2013年 | 656篇 |
2012年 | 633篇 |
2011年 | 803篇 |
2010年 | 340篇 |
2009年 | 307篇 |
2008年 | 707篇 |
2007年 | 703篇 |
2006年 | 665篇 |
2005年 | 557篇 |
2004年 | 429篇 |
2003年 | 419篇 |
2002年 | 376篇 |
2001年 | 355篇 |
2000年 | 285篇 |
1999年 | 226篇 |
1998年 | 193篇 |
1997年 | 206篇 |
1996年 | 207篇 |
1995年 | 194篇 |
1994年 | 172篇 |
1993年 | 204篇 |
1992年 | 203篇 |
1991年 | 164篇 |
1990年 | 143篇 |
1989年 | 130篇 |
1988年 | 120篇 |
1987年 | 130篇 |
1986年 | 143篇 |
1985年 | 156篇 |
1984年 | 188篇 |
1983年 | 165篇 |
1982年 | 173篇 |
1981年 | 187篇 |
1980年 | 166篇 |
1979年 | 153篇 |
1978年 | 171篇 |
1977年 | 166篇 |
1976年 | 143篇 |
1975年 | 137篇 |
1974年 | 127篇 |
1973年 | 115篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
A calibration technique for the constant-temperature hot-wire anemometer is presented, which is based on traversing the probe
through the boundary layer of a flat plate while simultaneously performing fluctuation measurements. The free stream Mach
number was M = 2.54, and the Reynolds number Red, based on wire diameter, ranged from 9 to 23. A comparison of the sensitivity values obtained with the aid of such a calibration
procedure — under the condition of neglecting low temperature loadings (t<0.6) — agrees well with sensitivities determined with free-stream data-The use of a modified transfer function for correcting
the power spectra of flow perturbations revealed a conformity of wide parts of the corrected spectra with the Kolmogorov decay.
The fluctuation levels of total temperature and mass flux were computed for the boundary layer of a flat plate.
This work was presented at the International Conference on the Methods of Aerophysical Research ICMAR 2007, which was held
in Novosibirsk on 5–10 February 2007. 相似文献
53.
Let R be a local ring and let (x
1, …, x
r) be part of a system of parameters of a finitely generated R-module M, where r < dimR
M. We will show that if (y
1, …, y
r) is part of a reducing system of parameters of M with (y
1, …, y
r) M = (x
1, …, x
r) M then (x
1, …, x
r) is already reducing. Moreover, there is such a part of a reducing system of parameters of M iff for all primes P ε Supp M ∩ V
R(x
1, …, x
r) with dimR
R/P = dimR
M − r the localization M
P of M at P is an r-dimensional Cohen-Macaulay module over R
P.
Furthermore, we will show that M is a Cohen-Macaulay module iff y
d is a non zero divisor on M/(y
1, …, y
d−1) M, where (y
1, …, y
d) is a reducing system of parameters of M (d:= dimR
M). 相似文献
54.
55.
J. Walz S. B. Ross C. Zimmermann L. Ricci M. Prevedelli T. W. Hänsch 《Hyperfine Interactions》1996,100(1):133-144
Experiments with electrons and ions in a combined trap are reported. The unique capability to confine particles with opposite charge and very different mass simultaneously in the same spatial region makes the combined trap a promising device for future synthesis of antihydrogen. 相似文献
56.
A quick sample preparation method was used for the determination of sulphur and trace metals in oil and oily products by the ICP with a minitorch. Stable aqueous emulsions of oils and oil products were made by using two kinds of emulsifiers (one with low sulphur content, the other sulfonated). Aqueous standard solutions can be used for the preparation of calibration solutions. The contents of S, Al, Cr, Cu, Fe, Mg, Ni and Pb in aqueous emulsions were determined and the results were in good agreement with the composition of oil standard solutions used for control analysis procedure. 相似文献
57.
We introduce triplet spaces for symmetric relations with defect index (1, 1) in a Pontryagin space. Representations of Pontryagin spaces by spaces of vector-valued analytic functions are investigated. These concepts are used to study 2×2-matrix valued analytic functions which satisfy a certain kernel condition. 相似文献
58.
59.
T.R. Saitoh N. Hashimoto G. Sletten R.A. Bark S. Törmänen M. Bergström K. Furuno K. Furutaka G.B. Hagemann T. Hayakawa T. Komatsubara A. Maj S. Mitarai M. Oshima J. Sampson T. Shizuma P.G. Varmette 《The European Physical Journal A - Hadrons and Nuclei》1998,3(3):197-199
High-spin states in 181Ta have been studied via the 176Yb(11B,α2n) reaction at 52 MeV using the PEX array and at 57 MeV using the NORDBALL array, with α-particle detection. The previously
known, Kπ=(7/2)+ ground state band and Kπ=(9/2)− band have been extended to spins (29/2)+ and (31/2)−, respectively. Two new one-quasiparticle bands, the Kπ=(5/2)+ band built on the known (5/2)+ isomer and a Kπ=((1/2)−) band have been observed. Two other rotational bands with three-quasiparticle structure, Kπ=(15/2)− and ((19/2)+ with π(7/2)[404]ν2(1/2)[510](9/2)[624] and π(9/2)[514]ν2(1/2)[510](9/2)[624] configurations, respectively, have been newly observed. The half-life of the Kπ=((19/2)+) bandhead which decays to the head of the (15/2)− band has been measured to be 140(36) ns. However, transitions from the ((19/2)+) state to the (15/2)− band have not been observed.
Received: 26 August 1998 相似文献
60.
A. Bachem W. Hochstättler B. Steckemetz A. Volmer 《Computational Optimization and Applications》1996,6(3):213-225
We report on computational experience with an implementation of three algorithms for the general economic equilibrium problem. As a result we get that the projection algorithm for variational inequalities increases the size of solvable models by a factor of 5–10 in comparison with the classical homotopy method. As a third approach we implemented a simulated annealing heuristic which might be suitable to estimate equilibria for very large models.Supported by the German Research Association (Deutsche Forschungsgemeinschaft, SFB 303). 相似文献