全文获取类型
收费全文 | 980篇 |
免费 | 26篇 |
国内免费 | 2篇 |
专业分类
化学 | 585篇 |
晶体学 | 8篇 |
力学 | 48篇 |
数学 | 187篇 |
物理学 | 180篇 |
出版年
2023年 | 12篇 |
2022年 | 14篇 |
2021年 | 27篇 |
2020年 | 17篇 |
2019年 | 18篇 |
2018年 | 10篇 |
2017年 | 14篇 |
2016年 | 28篇 |
2015年 | 31篇 |
2014年 | 31篇 |
2013年 | 64篇 |
2012年 | 70篇 |
2011年 | 68篇 |
2010年 | 47篇 |
2009年 | 34篇 |
2008年 | 50篇 |
2007年 | 46篇 |
2006年 | 42篇 |
2005年 | 35篇 |
2004年 | 26篇 |
2003年 | 32篇 |
2002年 | 24篇 |
2001年 | 21篇 |
2000年 | 11篇 |
1999年 | 9篇 |
1997年 | 11篇 |
1996年 | 12篇 |
1995年 | 13篇 |
1994年 | 19篇 |
1993年 | 10篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 10篇 |
1989年 | 3篇 |
1988年 | 8篇 |
1987年 | 9篇 |
1986年 | 3篇 |
1985年 | 10篇 |
1984年 | 13篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 7篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1974年 | 7篇 |
1973年 | 6篇 |
1966年 | 3篇 |
排序方式: 共有1008条查询结果,搜索用时 468 毫秒
1.
2.
We report on the realization and characterization of electro-responsive and pressure sensitive polydimethylsiloxane (PDMS) conductive photonic structures combined with the reconfigurable properties of short pitch cholesteric liquid crystals (aligned in Grandjean configuration). By combining ion-implantation process and surface chemistry functionalization, we have overcome the insulating properties of PDMS and induced long range organization of cholesteric liquid crystals, thus controlling both diffraction and selective Bragg reflection of light by means of external perturbations (electric field, pressure). We have characterized our devices in terms of morphological, optical and electro-optical properties. 相似文献
3.
4.
5.
M.C. Ubaldi V. Stasi U. Colombo D. Piccinin M. Martinelli 《Photonics and Nanostructures》2007,5(2-3):145-148
Roughness reduction of a submicron waveguide profile in chemically amplified negative resist is here performed by proper selection of an alkali-based developer, taking into account that its smaller molecules lead to smoother resist surface by altering the developing mechanism of aggregate extraction performed with standard quaternary ammonium hydroxide. Roughness is then analyzed by means of classical Atomic Force Microscope inspection; furthermore, a non-invasive line edge roughness analysis approach based on top-down scanning electron microscope acquisition gives comparable results, in terms of standard deviation and molecular aggregate periodicity. 相似文献
6.
Modern trends in designing mechatronic systems call for a synergic design of the separated subsystems (mechanic, electronic parts, control modules, etc.) concurring to the overall performance. Following this point of view, this paper presents a control oriented model and a nonlinear control design for a Common Rail injection system. First a model is developed, which is tuned in a virtual simulation environment, representing the injection system in details in a reliable replication of reality. Then a sliding mode control is developed. Both the model of the injection process and of the control law are validated by a virtual detailed simulation environment. The prediction capability of the model and the control efficiency are clearly shown. 相似文献
7.
8.
Substrate relaxation is shown to play an important role in the 1 : 2 regular chemisorption of hydrogen atoms above alternate carbon atoms in a graphite monolayer. Binding energy, population analysis and electron density maps show that the direct HC bond is strengthened on relaxation. 相似文献
9.
A multiresidue method for isolation and liquid chromatographic determination of oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) in milk is presented. The sensitivity of the method is adequate to meet the needs of regulatory agencies. The European Community established 100 micrograms/kg as the maximum residue limit (MRL) in milk for TC, CTC, and OTC. Recoveries exceeded 80% for all tetracyclines at all levels, with good precision. Correlation coefficients of standards curves for individual tetracyclines isolated from fortified samples ranged from 0.991 for CTC to 0.998 for OTC. Other antibiotics that might interfere with analysis did not interfere with elution times of OTC, TC, and CTC. The procedure is rapid, precise, and quantitative and requires minimal preparation and minimal use of organic solvents. It can be applied to routine surveillance programs. We can prepare 10 samples for analysis in about 1.45 h. 相似文献
10.