全文获取类型
收费全文 | 3524篇 |
免费 | 122篇 |
国内免费 | 27篇 |
专业分类
化学 | 2480篇 |
晶体学 | 19篇 |
力学 | 53篇 |
数学 | 552篇 |
物理学 | 569篇 |
出版年
2024年 | 5篇 |
2023年 | 27篇 |
2022年 | 65篇 |
2021年 | 97篇 |
2020年 | 86篇 |
2019年 | 105篇 |
2018年 | 118篇 |
2017年 | 80篇 |
2016年 | 136篇 |
2015年 | 127篇 |
2014年 | 145篇 |
2013年 | 200篇 |
2012年 | 239篇 |
2011年 | 259篇 |
2010年 | 172篇 |
2009年 | 112篇 |
2008年 | 242篇 |
2007年 | 242篇 |
2006年 | 214篇 |
2005年 | 189篇 |
2004年 | 148篇 |
2003年 | 119篇 |
2002年 | 99篇 |
2001年 | 44篇 |
2000年 | 30篇 |
1999年 | 36篇 |
1998年 | 34篇 |
1997年 | 21篇 |
1996年 | 32篇 |
1995年 | 23篇 |
1994年 | 29篇 |
1993年 | 15篇 |
1992年 | 11篇 |
1991年 | 11篇 |
1989年 | 8篇 |
1988年 | 11篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 9篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1981年 | 6篇 |
1980年 | 9篇 |
1979年 | 8篇 |
1977年 | 5篇 |
1976年 | 12篇 |
1975年 | 11篇 |
1973年 | 7篇 |
1972年 | 4篇 |
1954年 | 5篇 |
排序方式: 共有3673条查询结果,搜索用时 0 毫秒
51.
Dr. Pavel K. Mykhailiuk Prof. Dr. Rene M. Koenigs 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(1):89-101
Diazoacetonitrile (N2CHCN) is a small reactive diazoalkane. It has been synthesized for the first time already in 1898 by Theodor Curtius, however, did not gain much recognition in organic synthesis until recently. Only in 2015, after introduction of in situ and flow protocols for the safe generation of diazoacetonitrile, it started gaining popularity. In this minireview, the synthetic properties and applications of this valuable reagent are discussed. 相似文献
52.
53.
54.
Pavel Exner Takashi Ichinose Hagen Neidhardt Valentin A. Zagrebnov 《Integral Equations and Operator Theory》2007,57(1):67-81
We introduce a new product formula which combines an orthogonal projection with a complex function of a non-negative operator.
Under certain assumptions on the complex function the strong convergence of the product formula is shown. Under more restrictive
assumptions even operator-norm convergence is verified. The mentioned formula can be used to describe Zeno dynamics in the
situation when the usual non-decay measurement is replaced by a particular generalized observables in the sense of Davies. 相似文献
55.
Let D be a simply laced Dynkin diagram of rank r whose affinization has the shape of a star (i.e., D4,E6,E7,E8). To such a diagram one can attach a group G whose generators correspond to the legs of the affinization, have orders equal to the leg lengths plus 1, and the product of the generators is 1. The group G is then a 2-dimensional crystallographic group: G=Z??Z2, where ? is 2, 3, 4, and 6, respectively. In this paper, we define a flat deformation H(t,q) of the group algebra C[G] of this group, by replacing the relations saying that the generators have prescribed orders by their deformations, saying that the generators satisfy monic polynomial equations of these orders with arbitrary roots (which are deformation parameters). The algebra H(t,q) for D4 is the Cherednik algebra of type C∨C1, which was studied by Noumi, Sahi, and Stokman, and controls Askey-Wilson polynomials. We prove that H(t,q) is the universal deformation of the twisted group algebra of G, and that this deformation is compatible with certain filtrations on C[G]. We also show that if q is a root of unity, then for generic t the algebra H(t,q) is an Azumaya algebra, and its center is the function algebra on an affine del Pezzo surface. For generic q, the spherical subalgebra eH(t,q)e provides a quantization of such surfaces. We also discuss connections of H(t,q) with preprojective algebras and Painlevé VI. 相似文献
56.
A.M. Khvedelidze D.M. Mladenov H.-P. Pavel G. Röpke 《The European Physical Journal C - Particles and Fields》2002,24(1):137-141
The Hamiltonian reduction of classical SU(2) Yang–Mills field theory to the equivalent unconstrained theory of gauge invariant local dynamical variables is generalized
to the case of nonvanishing -angle. It is shown that for any -angle the elimination of the pure gauge degrees of freedom leads to a corresponding unconstrained non-local theory of self-interacting
second rank symmetric tensor fields, and that the obtained classical unconstrained gluodynamics with different -angles are canonically equivalent as on the original constrained level.
Received: 16 November 2001 / Published online: 5 April 2002 相似文献
57.
Jan Wild Jiří Macl Hana Šíchová Pavel Boháček Jarmila Prachařová Pavel Kubát Svatopluk Civiš 《Czechoslovak Journal of Physics》1997,47(10):1025-1030
Bi(Pb)–Sr–Ca–Cu–O layers were prepared by laser ablation in air, that is without using a vacuum chamber. At this method a much higher density of pulse energy of laser beam is required (10–30 J cm–2) in comparison with the standard method (1–3 J cm–2). The mentioned condition has specific effects on the nature of the transport of material from the target. As follows from the electron microprobe analysis of the layers, the starting composition of the transported material is identical with that of the superconducting phase sintered in the target; one exception represents Pb, the content of which in the transported material is lower. The image of the process is complemented by UV/VIS spectroscopy scans of the plasma plume. 相似文献
58.
Krzysztof Pomorski José M. Blanco Pavel V. Kostryukov Artur Dobrowolski Bo?ena Nerlo-Pomorska Micha? Warda Zhi-Gang Xiao Yong-Jing Chen Li-Le Liu Jun-Long Tian Xin-Yue Diao Qiang-Hua Wu 《中国物理C(英文版)》2021,45(5):054109-054109-11
Fission properties of the actinide nuclei are deduced from theoretical analysis. We investigate potential energy surfaces and fission barriers and predict the fission fragment mass yields of actinide isotopes. The results are compared with experimental data where available. The calculations were performed in the macroscopic-microscopic approximation with the Lublin-Strasbourg Drop (LSD) for the macroscopic part, and the microscopic energy corrections were evaluated in the Yukawa-folded potential. The Fourier nuclear shape parametrization is used to describe the nuclear shape, including the non-axial degree of freedom. The fission fragment mass yields of the nuclei considered are evaluated within a 3D collective model using the Born-Oppenheimer approximation. 相似文献
59.
Bi Dongxue Sverbil Pavel P. Voinov Yury P. Wu Mengyuan 《Journal of Russian Laser Research》2021,42(6):671-676
Journal of Russian Laser Research - We discuss the use of high-pressure high-temperature (HPHT) diamonds for the determination of trace amounts of various Raman active substances. The amount of the... 相似文献
60.
We study the partial differential equation which arose originally as a scaling limit in the study of interface fluctuations in a certain spin system. In that application x lies in R, but here we study primarily the periodic case × R S1. We establish existence, uniqueness, and regularity of solutions, locally in time, for positive initial data in H1(S1), and prove the existence of several families of Lyapunov functions for the evolution. From the latter we establish a sharp connection between existence globally in time and positivity preservation: if [0], T*) is a maximal half open interval of existence for a positive solution of the equation, with T* < ∞, then limtT* w(t,·) exists in C1(S1) but vanishes at some point. We show further that if T* > (1 + √3)/16π2 √3 then T* = ∞ and limt∞ w(t,.) exists and is constant. We discuss also some explicit solutions and propose a generalization to higher dimensions. © 1994 John Wiley & Sons, Inc. 相似文献