全文获取类型
收费全文 | 8612篇 |
免费 | 254篇 |
国内免费 | 62篇 |
专业分类
化学 | 5819篇 |
晶体学 | 84篇 |
力学 | 260篇 |
综合类 | 1篇 |
数学 | 1324篇 |
物理学 | 1440篇 |
出版年
2022年 | 82篇 |
2021年 | 82篇 |
2020年 | 156篇 |
2019年 | 112篇 |
2018年 | 85篇 |
2017年 | 95篇 |
2016年 | 190篇 |
2015年 | 153篇 |
2014年 | 197篇 |
2013年 | 397篇 |
2012年 | 457篇 |
2011年 | 560篇 |
2010年 | 282篇 |
2009年 | 226篇 |
2008年 | 495篇 |
2007年 | 456篇 |
2006年 | 446篇 |
2005年 | 450篇 |
2004年 | 432篇 |
2003年 | 285篇 |
2002年 | 310篇 |
2001年 | 90篇 |
2000年 | 85篇 |
1999年 | 66篇 |
1998年 | 79篇 |
1997年 | 99篇 |
1996年 | 139篇 |
1995年 | 85篇 |
1994年 | 69篇 |
1993年 | 96篇 |
1992年 | 68篇 |
1991年 | 81篇 |
1990年 | 82篇 |
1989年 | 59篇 |
1988年 | 75篇 |
1987年 | 63篇 |
1986年 | 57篇 |
1985年 | 113篇 |
1984年 | 131篇 |
1983年 | 93篇 |
1982年 | 114篇 |
1981年 | 108篇 |
1980年 | 95篇 |
1979年 | 84篇 |
1978年 | 111篇 |
1977年 | 94篇 |
1976年 | 82篇 |
1975年 | 71篇 |
1974年 | 71篇 |
1973年 | 60篇 |
排序方式: 共有8928条查询结果,搜索用时 15 毫秒
21.
Joseph Barback 《Mathematical Logic Quarterly》1997,43(1):83-91
In this paper we present a collection of results related to the comparability of summands property of regressive isols. We show that if an infinite regressive isol has comparability of summands, then every predecessor of the isol has a weak comparability of summands property. Recently R. Downey proved that there exist regressive isols that are both hyper-torre and cosimple. There is a surprisingly close connection between non-recursive recursively enumerable sets and particular retraceable sets and regressive isols. We apply the theorem of Downey to show that among the regressive isols that are related to recursively enumerable sets there are some with a new property. 相似文献
22.
23.
Hua Zhang Nabil A. Amro Robert Elghanian Joseph Fragala 《Applied Surface Science》2006,253(4):1960-1963
A method, combining micro-contact printing (μCP), wet chemical etching and reactive ion etching (RIE), is reported to fabricate microstructures on Si and SiOx. Positive and negative structures were generated based on different stamps used for μCP. The reproducibility of the obtained microstructures shows the methodology reported herein could be useful in Micro-Electro-Mechanical Systems (MEMS), optical and biological sensing applications. 相似文献
24.
The incidence of the cutaneous malignant melanoma is increasing rapidly in the world [Ferlay J, Bray F, Pisani P, et al. GLOBOCAN 2000: Cancer incidence, mortality and prevalence worldwide, Version 1.0 IARC Cancer Base no. 5. Lyon: IARC Press, 2001]. The therapeutic address requires a method having high sensitivity and capability to diagnose such disease at an early stage. We introduce a new diagnostic method based on non-linear methodologies. In detail we suggest that fractal as well as noise and chaos dynamics are the most important components responsible for genetic instability of melanocytes. As consequence we introduce the new technique of the variogram and of fractal analysis extended to the whole regions of interest of skin in order to obtain parameters able to identify the malignant lesion. In a preliminary analysis, satisfactory results are reached. 相似文献
25.
26.
27.
Joseph B. Schlenoff W. Jack Rink Lawrence Seger 《Physica C: Superconductivity and its Applications》1991,180(5-6):387-393
Single crystals and polycrystalline pellets of the high-temperature cuprate superconductor Bi2Sr2Ca1Cu2O8 were doped at room temperature by electrochemical reduction at > 95% Coulombic efficiency using lithium dopant ions in propylene carbonate electrolyte. Cyclic voltammetry and potential step measurements on single crystals suggest an unusual reduction mechanism, with a diffusion coefficient for Li+ in the c-axis direction of bulk superconductor of ca. 3 × 10−11 cm2s−1. Sintered pellets of polycrystalline powder could be doped more rapidly, with an apparent diffusion coefficient of 7 × 10−8 cm2s−1. X-ray susceptibility analysis show extensive disordering occurs on heavy Li doping, with a first-order transition from a crystalline/superconducting to an amorphous/non-superconducting phase. Single, crystals of Bi2Sr2Ca1Cu2O8 exhibited a color change on reduction from metallic gray to golden bronze. The reduced material was highly air-sensitive, forming a hydroxide surface film on exposure to ambient atmosphere. 相似文献
28.
29.
Francis J. Narcowich Joseph D. Ward Holger Wendland. 《Mathematics of Computation》2005,74(250):743-763
In this paper we discuss Sobolev bounds on functions that vanish at scattered points in a bounded, Lipschitz domain that satisfies a uniform interior cone condition. The Sobolev spaces involved may have fractional as well as integer order. We then apply these results to obtain estimates for continuous and discrete least squares surface fits via radial basis functions (RBFs). These estimates include situations in which the target function does not belong to the native space of the RBF.
30.
In this paper a new proof of an identity of Giacomin, Olla, and Spohn is given. The identity relates the 2 point correlation function of a Euclidean field theory to the expectation of the Green's function for a pde with random coefficients. The Euclidean field theory is assumed to have convex potential. An inequality of Brascamp and Lieb therefore implies Gaussian bounds on the Fourier transform of the 2 point correlation function. By an application of results from random pde, the previously mentioned identity implies pointwise Gaussian bounds on the 2 point correlation function. 相似文献