全文获取类型
收费全文 | 3843篇 |
免费 | 182篇 |
国内免费 | 12篇 |
专业分类
化学 | 2812篇 |
晶体学 | 8篇 |
力学 | 141篇 |
数学 | 481篇 |
物理学 | 595篇 |
出版年
2023年 | 38篇 |
2022年 | 65篇 |
2021年 | 81篇 |
2020年 | 87篇 |
2019年 | 85篇 |
2018年 | 72篇 |
2017年 | 58篇 |
2016年 | 126篇 |
2015年 | 110篇 |
2014年 | 144篇 |
2013年 | 178篇 |
2012年 | 301篇 |
2011年 | 342篇 |
2010年 | 151篇 |
2009年 | 146篇 |
2008年 | 283篇 |
2007年 | 246篇 |
2006年 | 242篇 |
2005年 | 237篇 |
2004年 | 198篇 |
2003年 | 117篇 |
2002年 | 134篇 |
2001年 | 37篇 |
2000年 | 28篇 |
1999年 | 31篇 |
1998年 | 15篇 |
1997年 | 28篇 |
1996年 | 32篇 |
1995年 | 16篇 |
1994年 | 24篇 |
1993年 | 23篇 |
1992年 | 26篇 |
1991年 | 9篇 |
1990年 | 19篇 |
1989年 | 13篇 |
1988年 | 12篇 |
1986年 | 11篇 |
1985年 | 24篇 |
1984年 | 21篇 |
1983年 | 15篇 |
1982年 | 18篇 |
1981年 | 22篇 |
1980年 | 14篇 |
1979年 | 18篇 |
1978年 | 18篇 |
1977年 | 19篇 |
1976年 | 14篇 |
1975年 | 16篇 |
1974年 | 16篇 |
1973年 | 8篇 |
排序方式: 共有4037条查询结果,搜索用时 0 毫秒
101.
102.
103.
104.
105.
Dr. Julie Jung M. Ashraful Islam Dr. Vincent L. Pecoraro Dr. Talal Mallah Dr. Claude Berthon Dr. Hélène Bolvin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(66):15112-15122
Two series of lanthanide complexes have been chosen to analyze trends in the magnetic properties and crystal field parameters (CFPs) along the two series: The highly symmetric LnZn16(picHA)16 series (Ln=Tb, Dy, Ho, Er, Yb; picHA=picolinohydroxamic acid) and the [Ln(dpa)3](C3H5N2)3 ⋅ 3H2O series (Ln=Ce–Yb; dpa=2,6-dipicolinic acid) with approximate three-fold symmetry. The first series presents a compressed coordination sphere of eight oxygen atoms whereas in the second series, the coordination sphere consists of an elongated coordination sphere formed of six oxygen atoms. The CFPs have been deduced from ab initio calculations using two methods: The AILFT (ab initio ligand field theory) method, in which the parameters are determined at the orbital level, and the ITO (irreducible tensor operator) decomposition, in which the problems are treated at the many-electron level. It has been found that the CFPs are transferable from one derivative to another, within a given series, as a first approximation. The sign of the second-order parameter differs in the two series, reflecting the different environments. It has been found that the use of the strength parameter S allows for an easy comparison between complexes. Furthermore, in both series, the parameters have been found to decrease in magnitude along the series, and this decrease is attributed to covalent effects. 相似文献
106.
107.
Dr. Dhanaji V. Jawale Dr. Edmond Gravel Dr. Nimesh Shah Dr. Vincent Dauvois Prof. Dr. Haiyan Li Prof. Dr. Irishi N. N. Namboothiri Dr. Eric Doris 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7039-7042
Rhodium nanoparticles were anchored on carbon nanotubes and the resulting nanohybrid was studied as co‐catalyst, along with tert‐butylcatechol, for the dehydrogenation of various N‐heterocycles. The co‐catalytic system operates in high yields, under the mildest conditions reported so far, and can be applied to a wide variety of secondary amine‐containing scaffolds. 相似文献
108.
Vladimir Dolgovskiy Stéphane Schilt Nikola Bucalovic Gianni Di Domenico Serge Grop Benoît Dubois Vincent Giordano Thomas Südmeyer 《Applied physics. B, Lasers and optics》2014,116(3):593-601
We demonstrate the first ultra-stable microwave generation based on a 1.5-μm diode-pumped solid-state laser (DPSSL) frequency comb. Our system relies on optical-to-microwave frequency division from a planar-waveguide external cavity laser referenced to an ultra-stable Fabry–Perot cavity. The evaluation of the microwave signal at ~10 GHz uses the transportable ultra-low-instability signal source ULISS®, which employs a cryo-cooled sapphire oscillator. With the DPSSL comb, we measured ?125 dBc/Hz phase noise at 1 kHz offset frequency, likely limited by the photo-detection shot-noise or by the noise floor of the reference cryo-cooled sapphire oscillator. For comparison, we also generated low-noise microwave using a commercial Er:fiber comb stabilized in similar conditions and observed >20 dB lower phase noise in the microwave generated from the DPSSL comb. Our results confirm the high potential of the DPSSL technology for low-noise comb applications. 相似文献
109.
Vincent S. D. Voet Gerrit ten Brinke Katja Loos 《Journal of polymer science. Part A, Polymer chemistry》2014,52(20):2861-2877
Poly(vinylidene fluoride) (PVDF) has reached the second largest production volume of fluoropolymers in recent years, and its popularity can be ascribed to high thermal stability and chemical inertness combined with its ferroelectric behavior. Copolymerization of vinylidene fluoride with other monomers leads to a wide variety of products with modified or improved properties. Besides commercially available fluorinated random copolymers, well‐defined block‐, graft, and alternating copolymers based on PVDF received more attention in recent years. PVDF‐containing block copolymers that may self‐assemble into well‐ordered morphologies are of particular interest, being potential precursors for functional nanostructured materials applicable in membranes and electronics. This Highlight provides an overview of the routes developed towards these materials via conventional and controlled polymerization techniques. In addition, it discusses their nanoscopic phase behavior and current and potential applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2861–2877 相似文献
110.
Pierre Garcia Dr. Yannick Evanno Dr. Pascal George Dr. Mireille Sevrin Dr. Gino Ricci Prof. Dr. Max Malacria Dr. Corinne Aubert Prof. Dr. Vincent Gandon 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(14):4337-4344
An in‐depth study of the cobalt‐catalyzed [2+2+2] cycloaddition between yne‐ynamides and nitriles to afford aminopyridines has been carried out. About 30 nitriles exhibiting a broad range of steric demand and electronic properties have been evaluated, some of which open new perspectives in metal‐catalyzed arene formation. In particular, the use of [CpCo(CO)(dmfu)] (dmfu=dimethyl fumarate) as a precatalyst made possible the incorporation of electron‐deficient nitriles into the pyridine core. Modification of the substitution pattern at the yne‐ynamide allows the regioselectivity to be switched toward 3‐ or 4‐aminopyridines. Application of this synthetic methodology to the construction of the aminopyridone framework using a yne‐ynamide and an isocyanate was also briefly examined. DFT computations suggest that 3‐aminopyridines are formed by formal [4+2] cycloaddition between the nitrile and the intermediate cobaltacyclopentadiene, whereas 4‐aminopyridines arise from an insertion pathway. 相似文献