全文获取类型
收费全文 | 3206篇 |
免费 | 138篇 |
国内免费 | 7篇 |
专业分类
化学 | 2377篇 |
晶体学 | 37篇 |
力学 | 36篇 |
数学 | 427篇 |
物理学 | 474篇 |
出版年
2023年 | 16篇 |
2022年 | 25篇 |
2021年 | 40篇 |
2020年 | 58篇 |
2019年 | 60篇 |
2018年 | 27篇 |
2017年 | 39篇 |
2016年 | 92篇 |
2015年 | 96篇 |
2014年 | 117篇 |
2013年 | 156篇 |
2012年 | 164篇 |
2011年 | 211篇 |
2010年 | 140篇 |
2009年 | 108篇 |
2008年 | 169篇 |
2007年 | 182篇 |
2006年 | 150篇 |
2005年 | 147篇 |
2004年 | 130篇 |
2003年 | 103篇 |
2002年 | 108篇 |
2001年 | 65篇 |
2000年 | 60篇 |
1999年 | 46篇 |
1998年 | 66篇 |
1997年 | 46篇 |
1996年 | 48篇 |
1995年 | 70篇 |
1994年 | 59篇 |
1993年 | 56篇 |
1992年 | 39篇 |
1991年 | 45篇 |
1990年 | 35篇 |
1989年 | 30篇 |
1988年 | 22篇 |
1987年 | 20篇 |
1986年 | 22篇 |
1985年 | 34篇 |
1984年 | 31篇 |
1983年 | 20篇 |
1982年 | 19篇 |
1981年 | 16篇 |
1980年 | 20篇 |
1979年 | 20篇 |
1978年 | 13篇 |
1977年 | 16篇 |
1975年 | 10篇 |
1973年 | 16篇 |
1972年 | 8篇 |
排序方式: 共有3351条查询结果,搜索用时 15 毫秒
51.
52.
53.
Continuing the recent work of the second author, we prove that the diophantine equation
for has exactly 12 solutions except when , when it has 16 solutions. If denotes one of the zeros of , then for we also find all with .
54.
The quantum group IGL
q
(N), the inhomogenization of GL
q
(N), is formulated with
-matrices. Theq-deformed universal enveloping algebra is constructed as the algebra of regular functionals in this formulation and contains the partial derivatives of the covariant differential calculus on the quantum space. 相似文献
55.
56.
Franck-Condon factor distributions for bound-to-continuum transitions of one-dimensional vibrational states are calculated
by a) using numerical integration, b) employing a finite number of square integrable harmonic oscillator functions. The methods
are generally applicable to any kind of bound or repulsive potential involved. Results are presented and compared to model
potential calculations previously reported by Krüger [1]. 相似文献
57.
Haiges R Vij A Boatz JA Schneider S Schroer T Gerken M Christe KO 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(2):508-517
The highly explosive molecules As(N(3))(3) and Sb(N(3))(3) were obtained in pure form by the reactions of the corresponding fluorides with (CH(3))(3)SiN(3) in SO(2) and purification by sublimation. The crystal structures and (14)N NMR, infrared, and Raman spectra were determined, and the results compared to ab initio second-order perturbation theory calculations. Whereas Sb(N(3))(3) possesses a propeller-shaped, pyramidal structure with perfect C(3) symmetry, the As(N(3))(3) molecule is significantly distorted from C(3) symmetry due to crystal packing effects. 相似文献
58.
X-Ray Structural Analyses of Cyclododecasulfur (S12) and Cyclododecasulfur-1-Carbon-disulfide (S12 · CS2) S12 · CS2 crystallizes in space group R&3macr;m–D with hexagonal lattice constants a = 1066.8(3), c = 1155.1(4) pm, Z = 3, dcalc. = 2.04 g · cm?3. The S12 molecules occupy sites of D3d symmetry with bond distance (dss) of 205.4(1) pm, bond angles (α) of 105.80(5) and 106.65(6)º and torsional angle (τ) of 87.20(7)º. The CS2 molecule interacts only very weakly with the S12 units. S12 crystallizes in space group Pnnm–D with lattice constants a = 472.5(2), b = 910.4(3), c = 1453.2(3) pm, Z = 2, dcalc = 2.045 g · cm?3. The molecules with mean parameters d = 205.2 pm, α 106.6º, τ 88.0º occupy sites of C2h symmetry. 相似文献
59.
A chemo- and regioselective cross-coupling reaction of the functionalized aryl triflate 5 with octylmagnesium bromide catalyzed by cheap, nontoxic, and environmentally benign Fe(acac)(3) sets the basis for a practical and scaleable synthesis of the octylbenzene derivative 6, which serves as a key building block for the preparation of FTY720 (1). This 2-amino-1,3-propanediol derivative shows highly promising immunosuppressive properties and is currently in human clinical phase III trials. 相似文献
60.
LoSecco JM Bionta RM Biewitt G Bratton CB Casper D Chrysicopoulou P Claus R Cortez BG Errede S Foster GW Gajewski W Ganezer KS Goldhaber M Haines TJ Jones TW Kielczewska D Kropp WR Learned JG Lehmann E Park HS Reines F Schultz J Seidel S Shumard E Sinclair D Sobel HW Stone JL Sulak L Svoboda R van der Velde JC Wuest C 《Physical review letters》1985,54(21):2299-2301