全文获取类型
收费全文 | 609篇 |
免费 | 39篇 |
国内免费 | 2篇 |
专业分类
化学 | 405篇 |
晶体学 | 5篇 |
力学 | 7篇 |
数学 | 118篇 |
物理学 | 115篇 |
出版年
2023年 | 9篇 |
2022年 | 5篇 |
2021年 | 23篇 |
2020年 | 22篇 |
2019年 | 22篇 |
2018年 | 13篇 |
2017年 | 5篇 |
2016年 | 27篇 |
2015年 | 20篇 |
2014年 | 27篇 |
2013年 | 39篇 |
2012年 | 43篇 |
2011年 | 40篇 |
2010年 | 21篇 |
2009年 | 27篇 |
2008年 | 31篇 |
2007年 | 42篇 |
2006年 | 38篇 |
2005年 | 36篇 |
2004年 | 26篇 |
2003年 | 18篇 |
2002年 | 19篇 |
2001年 | 8篇 |
2000年 | 12篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 8篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有650条查询结果,搜索用时 15 毫秒
121.
J.A. Chaos J. Gonzalo C.N. Afonso J. Perrière M.T. García-González 《Applied Physics A: Materials Science & Processing》2001,72(6):705-710
Laser ablation of single-crystal LiNbO3 in a gas environment is used to grow films on (100) Si substrates heated to 650 °C. The film composition and crystallinity
are studied as a function of the nature (reactive, O2, or inert, Ar) and pressure of the gas environment applied during deposition and cooling-down processes, the laser energy
density and the target–substrate distance. Experimental results show that a gas pressure close to 1 mbar is required to produce
stoichiometric films in either O2 or Ar. The modification of the laser energy density and the target–substrate distance allows us to improve the crystallinity
of the films that become textured along the (006) direction. The influence of the experimental parameters on the film properties
is discussed in the frame of the formation of a blast wave, that leads to the focusing of the expanding Li species and thus,
to the increase of the Li content in the films.
Received: 8 February 2001 / Accepted: 9 February 2001 / Published online: 3 May 2001 相似文献
122.
Gonzalo Zaror Stephen J. Guastello 《Nonlinear dynamics, psychology, and life sciences》2000,4(1):113-119
Project examined the cross-cultural generalizability of a model for leadership emergence based on the rugged landscape self-organization and the swallowtail catastrophe. Twelve groups of eight Chilean university students played the Island Commission game and rated each other on leadership behavior at the end of the one-hour activity. Analysis confirmed the replication of dynamical structure and critical points obtained previously from a U.S. sample. 相似文献
123.
Pedro Morales‐Bonilla Andrea Prez‐Cardea Esther Quintero‐Mrmol Jos Luis Arias‐Tllez Gonzalo J. Mena‐Rejn 《Heteroatom Chemistry》2006,17(4):254-260
Seven 2‐amino‐4‐aryl‐1,3‐thiazoles ( 1a–g ) and their corresponding 2‐aminoacetyl ( 2a–g ) and 2‐aminoacetyl‐5‐bromo ( 3a–g ) derivatives were synthesized and tested in vitro against 11 reference strains, three Gram‐positive and four Gram‐negative bacteria, two yeasts, and two moulds. Toxicity of the compounds was also evaluated using the brine shrimp test. Compounds 1a, 1b, 1e–g , and 3b showed moderate antimicrobial activity at different concentrations. The results indicated that acetylation of the amino group and bromination at position 5 of the thiazole moiety cause lost of activity. Compounds 1a, 1e , and 1f showed toxicity to brine shrimp nauplii below 10 ppm. Most other compounds showed moderate toxicity, LD50 above 100 ppm. Structures of all compounds were confirmed by NMR and MS data. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:254–260, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20182 相似文献
124.
Nerea Ruiz del Árbol Carlos Sánchez-Sánchez Gonzalo Otero-Irurueta José I. Martínez Pedro L. de Andrés Ana C. Gómez-Herrero Pablo Merino Marten Piantek David Serrate Paolo Lacovig Silvano Lizzit José Alemán Gary J. Ellis María F. López José A. Martín-Gago 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(51):23420-23427
On-surface synthesis is emerging as a highly rational bottom-up methodology for the synthesis of molecular structures that are unattainable or complex to obtain by wet chemistry. Here, oligomers of meta-polyaniline, a known ferromagnetic polymer, were synthesized from para-aminophenol building-blocks via an unexpected and highly specific on-surface formal 1,4 Michael-type addition at the meta position, driven by the reduction of the aminophenol molecule. We rationalize this dehydrogenation and coupling reaction mechanism with a combination of in situ scanning tunneling and non-contact atomic force microscopies, high-resolution synchrotron-based X-ray photoemission spectroscopy and first-principles calculations. This study demonstrates the capability of surfaces to selectively modify local molecular conditions to redirect well-established synthetic routes, such as Michael coupling, towards the rational synthesis of new covalent nanostructures. 相似文献
125.
David Cáceres-Castillo Gonzalo J. Mena-Rejón Carolina S. Castro-Segura 《Molecular physics》2020,118(6)
A theoretical mechanistic investigation of the cycloaddition reaction of quercetine with 3,5-di-tert-butyl-o-quinone has been carry out employing density functional calculations at M06-2X/6-31G(d,p) level of theory. This computational study was performed in order to gain insight in the energetic and structural parameters that rule the observed experimental selectivity in the synthetised cyclodimers obtained under classical heating and microwave irradiation conditions and the influence of the solvent on their chemical reactivity. The effect of the solvent in the selectivity was studied implicitly using the polarisable continuum model in absence and presence of one explicit solvent’s molecule. The theoretical results explain the main issues of the classical heating and the MWI reaction and suggest that thermal effects are directly responsible for the reaction selectivity observed. The comparison of the mechanistic pathway and the non-covalent interactions, shows that a dioxane assisted mechanism can explain the observed experimental selectivity of the two synthetised compounds, thus the dioxane molecule play a catalytic role on this hetero Diels–Alder reaction. 相似文献
126.
J. Gonzalo R. Gómez San Román J. Perrière C.N. Afonso R. Pérez Casero 《Applied Physics A: Materials Science & Processing》1998,66(5):487-491
2 , Ar) in a broad pressure range (10-7–1 mbar) are correlated to the plasma expansion dynamics. It is found that the deposited films present an excess of Ba in
the intermediate pressure range (10-2<P<10-1 mbar) and a peaked distribution of Ba to Ti atoms ratio, that is not related to either the substrate temperature or the nature
of the gas environment. The results are discussed in terms of the dependence of the plume length (LP) on the gas pressure and the existence of scattering processes for distances (d) from the target lower than LP and the diffusion of the ejected species for LP<d.
Received: 7 November 1997/Accepted: 8 November 1997 相似文献
127.
The optical behavior of a four-level tripod-type atomic system in a ring resonator driven by a cavity field and two external coherent fields is studied. It is shown that the atomic response exhibits an ultra-sensitive switch from high absorption to nearly transparency by changing the value of one of the control fields. The optical bistable response can be controlled by means of the external fields. The system can flip from the lower to the upper branch of the hysteresis curve without changing the incident probe. Switching and information storage of a light signal are predicted under appropriate triggering of the auxiliary external optical signals. 相似文献
128.
The existence of an asymptotic average of linking numbers ofperiodic orbits of a basic set of an Axiom A flow in S3 or R3is proved. 相似文献
129.
Inside Back Cover: An Expanded Porphycene with High NIR Absorptivity That Stabilizes Two Different Kinds of Metal Complexes (Angew. Chem. Int. Ed. 10/2018)
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
130.
Gonzalo Contreras-Barandiarán 《Communications in Mathematical Physics》1990,133(1):197-215
We give a formula for the rates of escape for Julia sets with preperiodic critical points and forC
endomorphisms of the interval with non-flat pre-periodic critical points outside the basin of attracting periodic points.Research supported by CNPq, Brasil 相似文献