全文获取类型
收费全文 | 2257篇 |
免费 | 82篇 |
国内免费 | 5篇 |
专业分类
化学 | 1384篇 |
晶体学 | 5篇 |
力学 | 69篇 |
数学 | 459篇 |
物理学 | 427篇 |
出版年
2024年 | 2篇 |
2023年 | 26篇 |
2022年 | 45篇 |
2021年 | 62篇 |
2020年 | 57篇 |
2019年 | 65篇 |
2018年 | 36篇 |
2017年 | 31篇 |
2016年 | 98篇 |
2015年 | 74篇 |
2014年 | 82篇 |
2013年 | 122篇 |
2012年 | 185篇 |
2011年 | 161篇 |
2010年 | 92篇 |
2009年 | 100篇 |
2008年 | 139篇 |
2007年 | 135篇 |
2006年 | 124篇 |
2005年 | 97篇 |
2004年 | 108篇 |
2003年 | 78篇 |
2002年 | 95篇 |
2001年 | 29篇 |
2000年 | 20篇 |
1999年 | 19篇 |
1998年 | 24篇 |
1997年 | 13篇 |
1996年 | 25篇 |
1995年 | 19篇 |
1994年 | 24篇 |
1993年 | 21篇 |
1992年 | 11篇 |
1991年 | 11篇 |
1990年 | 10篇 |
1989年 | 14篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 13篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1973年 | 2篇 |
1966年 | 3篇 |
排序方式: 共有2344条查询结果,搜索用时 31 毫秒
71.
Maria Ana Castro Adrian E. Roitberg Fabio D. Cukiernik 《Journal of computational chemistry》2013,34(15):1283-1290
A classical molecular mechanics force field, able to simulate coordination polymers (CP) based on ruthenium carboxylates (Ru2(O2CReq)4Lax) (eq = equatorial group containing aliphatic chains, Lax= axial ligand), has been developed. New parameters extracted from experimental data and quantum calculations on short aliphatic chains model systems were included in the generalized AMBER force field. The proposed parametrization was evaluated using model systems with known structure, containing either short or long aliphatic chains; experimental results were reproduced satisfactorily. This modified force field, although in a preliminary stage, could then be applied to long chain liquid crystalline compounds. The resulting atomistic simulations allowed assessing the relative influence of the factors determining the CP conformation, determinant for the physical properties of these materials. © 2013 Wiley Periodicals, Inc. 相似文献
72.
Jessica Walkenhorst Umberto De Giovannini Alberto Castro Angel Rubio 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(5):128
Recent advances in laser technology allow us to follow electronic motion at its natural time-scale with ultra-fast time resolution, leading the way towards attosecond physics experiments of extreme precision. In this work, we assess the use of tailored pumps in order to enhance (or reduce) some given features of the probe absorption (for example, absorption in the visible range of otherwise transparent samples). This type of manipulation of the system response could be helpful for its full characterization, since it would allow us to visualize transitions that are dark when using unshaped pulses. In order to investigate these possibilities, we perform first a theoretical analysis of the non-equilibrium response function in this context, aided by one simple numerical model of the hydrogen atom. Then, we proceed to investigate the feasibility of using time-dependent density-functional theory as a means to implement, theoretically, this absorption-optimization idea, for more complex atoms or molecules. We conclude that the proposed idea could in principle be brought to the laboratory: tailored pump pulses can excite systems into light-absorbing states. However, we also highlight the severe numerical and theoretical difficulties posed by the problem: large-scale non-equilibrium quantum dynamics are cumbersome, even with TDDFT, and the shortcomings of state-of-the-art TDDFT functionals may still be serious for these out-of-equilibrium situations. 相似文献
73.
Dr. Peter Wick Dr. Anna E. Louw‐Gaume Dr. Melanie Kucki Prof. Harald F. Krug Prof. Kostas Kostarelos Prof. Bengt Fadeel Prof. Kenneth A. Dawson Dr. Anna Salvati Prof. Ester Vázquez Dr. Laura Ballerini Dr. Mauro Tretiach Dr. Fabio Benfenati Dr. Emmanuel Flahaut Dr. Laury Gauthier Prof. Maurizio Prato Dr. Alberto Bianco 《Angewandte Chemie (International ed. in English)》2014,53(30):7714-7718
74.
Paula A. Delgado Piotr Matloka Fabio Zuluaga Kenneth B. Wagener 《Journal of polymer science. Part A, Polymer chemistry》2012,50(3):431-440
Acyclic diene metathesis (ADMET) polymerization has been used in the synthesis of telechelic materials using alkoxy‐functionalized carbosiloxane or oligo(oxyethylene)‐based polymers, varying from internal to terminal cured materials or the combination of them. Previous investigations demonstrated that introduction of chain‐end crosslinking improves the stress–strain behavior of such materials. A series of saturated and unsaturated carbosiloxane and oligo(oxyethylene)‐based polymers were synthesized by ADMET polymerization using silacyclobutane as chain‐end, thermally induced crosslinker. The carbosiloxane derivatives presented pure amorphous behavior, whereas the oligo(oxyethylene) polymers were semicrystalline. The thermal curing process was monitored by differential scanning calorimetry via the exotherm between 160 and 210 °C. Mechanical properties on thermoset polymers were measured, where cured polymers showed moduli from 0.6 to 9.3 MPa, tensile strengths from 0.3 to 1.0 MPa, and elongations from 12 to 76%. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
75.
76.
Marco Lopez Fabio Sacconi Matthias Auf der Maur Alessandro Pecchia Aldo Di Carlo 《Optical and Quantum Electronics》2012,44(3-5):89-94
In this work electronic and optoelectronic properties of InGaN/GaN nanocolumn quantum disk LEDs have been studied with the multiscale simulation tool tiberCAD. Calculations have been performed with an atomistic tight-binding model. Results shows that emission energies have a minor dependence on the nanocolumn dimension while In concentration in the active region is a critical parameter. 相似文献
77.
78.
79.
Carlos Raimundo Andrade Lima Jefferson da Silva Martins Caroline Pinheiro Luis Fernando de Avila Roberto Rosas Pinho Maria Luiza Miranda Rocco Wilson de Souza Melo Fabio Zappa 《Journal of Polymer Science.Polymer Physics》2019,57(15):967-972
Photopolymerization is a phenomenon that is the basis of much of today's microfabrication technology and intense research is conducted to improve its control and the characteristics of end products for a variety of applications. The design of microscopic structures often relies on the accurate knowledge and modeling of photopolymer's behavior upon exposure, i.e. the Dill parameters, for each radiation species of interest and therefore the development of flexible characterization techniques is of great importance. SU‐8 is a popular compound that is representative of a whole class that relies on cationic polymerization, where an acid is obtained via photolysis of an onium salt during exposure. Here we report on the observation of SbF6? via laser desorption mass spectrometry on SU‐8 exposed to UV light at the wavelength of 365 nm and demonstrate that the yield of this counter‐anion as a function of exposure is consistent with the Dill C parameter value available in the literature. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 967–972 相似文献
80.
Meccanica - The advancement of manufacturing techniques has led to a rapid increase in the design and fabrication of periodic and architectured materials for a variety of dynamics and wave... 相似文献