全文获取类型
收费全文 | 3812篇 |
免费 | 109篇 |
国内免费 | 4篇 |
专业分类
化学 | 2920篇 |
晶体学 | 19篇 |
力学 | 39篇 |
数学 | 407篇 |
物理学 | 540篇 |
出版年
2023年 | 28篇 |
2022年 | 38篇 |
2021年 | 61篇 |
2020年 | 56篇 |
2019年 | 58篇 |
2018年 | 49篇 |
2017年 | 57篇 |
2016年 | 94篇 |
2015年 | 115篇 |
2014年 | 107篇 |
2013年 | 218篇 |
2012年 | 287篇 |
2011年 | 307篇 |
2010年 | 148篇 |
2009年 | 109篇 |
2008年 | 268篇 |
2007年 | 268篇 |
2006年 | 265篇 |
2005年 | 230篇 |
2004年 | 169篇 |
2003年 | 148篇 |
2002年 | 114篇 |
2001年 | 91篇 |
2000年 | 96篇 |
1999年 | 34篇 |
1998年 | 24篇 |
1997年 | 30篇 |
1996年 | 40篇 |
1995年 | 33篇 |
1994年 | 28篇 |
1993年 | 21篇 |
1992年 | 35篇 |
1991年 | 23篇 |
1990年 | 20篇 |
1989年 | 13篇 |
1988年 | 16篇 |
1987年 | 12篇 |
1986年 | 10篇 |
1985年 | 29篇 |
1984年 | 16篇 |
1983年 | 9篇 |
1982年 | 17篇 |
1981年 | 11篇 |
1980年 | 19篇 |
1979年 | 12篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1974年 | 7篇 |
1972年 | 9篇 |
排序方式: 共有3925条查询结果,搜索用时 46 毫秒
1.
2.
3.
Synthesis,Electronic Properties and WOLED Devices of Planar Phosphorus‐Containing Polycyclic Aromatic Hydrocarbons
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. François Riobé Rózsa Szűcs Dr. Pierre‐Antoine Bouit Dr. Denis Tondelier Bernard Geffroy Fátima Aparicio Julia Buendía Prof. Luis Sánchez Prof. Régis Réau Prof. László Nyulászi Prof. Muriel Hissler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(17):6547-6556
We describe the synthesis and the physical properties of polyaromatic hydrocarbons (PAHs) containing a phosphorus atom at the edge. In particular, the impact of the successive addition of aromatic rings on the electronic properties was investigated by experimental (UV/Vis absorption, fluorescence, cyclic voltammetry) and theoretical studies (DFT). The physical properties recorded in solution and in the solid state showed that the P‐containing PAHs exhibit properties expected for an emitter in white organic light‐emitting diodes (WOLEDs). 相似文献
4.
5.
The function lattice, or generalized Boolean algebra, is the set of ℓ-tuples with the ith coordinate an integer between 0 and a bound ni. Two ℓ-tuples t-intersect if they have at least t common nonzero coordinates. We prove a Hilton–Milner type theorem for systems of t-intersecting ℓ-tuples.Received September 29, 2004 相似文献
6.
Y. A. Coutinho J. A. Martins Simões C. M. Porto 《Zeitschrift fur Physik C Particles and Fields》1997,73(4):705-709
In this paper we investigate the effects of heavy Majorana neutrinos in the reaction e + e ? → W + W ?. We consider neutrino masses in the 1–10 TeV region. We show that at LEP II and NLC energies it is possible to use this processes to verify indirect evidence of heavy neutral particles with mixing angles of the order sin2 α = 0.01. We discuss the unitarity restrictions that can be obtained for vector singlet and fermion-mirror-fermion models. 相似文献
7.
One of the shortcomings of R&D evaluation is a lack of emphasis on analytical assessment of the value of an on-going R&D project. This paper addresses the problem concerning the distributive aspect of access to superior knowledge. Decision tree analysis and probability models appear to be appropriate tools for assessing the values of an intermediate result and patent reward of a firm's R&D decision in an environment of perfect information and oligopolistic competition. The assessed values are used as minimum prices acceptable to the firm when the knowledge is disseminated to the public. This paper will attempt to resolve this problem through the determination of the appropriate values of the reservation price of the first-stage invention in terms of the final reward and of a patent reward for which the inventor is willing to apply. 相似文献
8.
Carolina Pereira De Souza Margareth Spangler Andrade Bernardo Ruegger Almeida Neves 《Microscopy and microanalysis》2002,8(6):509-517
In this work, effective, yet simple, recycling mechanisms for used scanning probe microscopy (SPM) tips were implemented. Comprising a tip profile characterization methodology and specific cleaning procedures, which decontaminate SPM tips whether the contamination nature is known or not, such routes were optimized during numerous tests with brand new, previously used, and already discarded categories of SPM tips. The results show that if the used tip suffered contamination only, but no physical damages, during its scanning lifetime, it becomes readily available for reutilization after the cleansing process, characterizing a recycling route. On the other hand, if the tip went through wear and breakages during its utilization, it still can be decontaminated, but may not be directly reutilized due to its inadequate physical profile. Nevertheless, the methodology developed in this work may yet be applied as part of a more complex recycling route. 相似文献
9.
Chi Kin Chau Kwang Mong Sim 《Operations Research Letters》2003,31(5):327-334
By showing that there is an upper bound for the price of anarchyρ(Γ) for a non-atomic congestion game Γ with only separable cost maps and fixed demands, Roughgarden and Tardos show that the cost of forgoing centralized control is mild. This letter shows that there is an upper bound for ρ(Γ) in Γ for fixed demands with symmetric cost maps. It also shows that there is a weaker bound for ρ(Γ) in Γ with elastic demands. 相似文献
10.
Jien Wu Xiao-Fang Cheng Leslie J. Harrison Swee-Hock Goh Keng-Yeow Sim 《Tetrahedron letters》2004,45(52):9657-9659
Examination of the aerial parts of a Chinese herbal medicine yielded a novel metabolite, perforatumone 1, which is characterized by its unique carbon skeleton. Its structure was determined by detailed spectroscopic analysis. 相似文献