全文获取类型
收费全文 | 681篇 |
免费 | 42篇 |
国内免费 | 2篇 |
专业分类
化学 | 360篇 |
晶体学 | 4篇 |
力学 | 23篇 |
数学 | 106篇 |
物理学 | 232篇 |
出版年
2024年 | 3篇 |
2023年 | 15篇 |
2022年 | 16篇 |
2021年 | 21篇 |
2020年 | 25篇 |
2019年 | 20篇 |
2018年 | 27篇 |
2017年 | 24篇 |
2016年 | 48篇 |
2015年 | 34篇 |
2014年 | 28篇 |
2013年 | 50篇 |
2012年 | 42篇 |
2011年 | 54篇 |
2010年 | 42篇 |
2009年 | 27篇 |
2008年 | 25篇 |
2007年 | 22篇 |
2006年 | 25篇 |
2005年 | 17篇 |
2004年 | 8篇 |
2003年 | 10篇 |
2002年 | 15篇 |
2001年 | 11篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 9篇 |
1995年 | 3篇 |
1994年 | 9篇 |
1993年 | 16篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 11篇 |
1989年 | 5篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有725条查询结果,搜索用时 390 毫秒
161.
162.
A Fast and Facile Fabrication of PTFE Based Superhydrophobic and Ultra Wideband Angle Insensitive Anti‐Reflection Coatings (Phys. Status Solidi RRL 6/2018)
下载免费PDF全文
![点击此处可从《固体物理学:研究快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
163.
164.
Nano-sized polyacrylonitrile (PAN) particles were prepared under the catalytic effect of in situ developed CoCl2/EDTA complex with ammonium persulfate as the initiator in the absence of any added emulsifier. The emulsion polymerization was studied at varying concentrations of the initiator, monomer, complex and solvent over a temperature range of 30-70oC. The overall activation energy (Ea, 49.79 kJ/mol), energy of dissociation of initiator (Ed, 82.68 kJ/mol), number of micelles (0.163 x 1018) and the viscosity average molecular weight of the polymer were computed. The distribution of particle sizes was determined by transmission electron microscopy (TEM). It was found that the oil-in-water polymerization was stabilized by the presence of the CoCl2/EDTA in situ complex reducing the particle size into the nano order. The average diameters of PAN nano particles, obtained by TEM, were in the range of 50–150 nm at the maximum conversion. The experimental particle size was mainly dependent on the concentration of the complex and temperature. 相似文献
165.
We propose a new scheme for measuring scale elasticity of production based on a new cost efficiency model developed in Tone
(2002). Comparing our model with classical model we establish the superiority of our model over the latter based on the premise
that the classical estimates of cost efficiency and scale elasticity can be illusory. 相似文献
166.
Labanya Bhattacharya Smruti R. Sahoo Sagar Sharma Sridhar Sahu 《International journal of quantum chemistry》2019,119(18):e25982
We report a density functional theory study of the effect of electron-withdrawing groups such as –F, –CN, –NO2 on the geometrical, optoelectronic, intramolecular charge transfer (ICT), and photovoltaic properties of (E)-1,2-bis(5-alkyl-[2,3′-bithiophene]-2′-yl)ethene (TVT-T) based donor-acceptor (D-A) copolymers with different acceptor units, that is, benzo[c][1,2,5]thiadiazole, benzo[c][1,2,5]oxadiazole, and benzo[c][1,2,5]selenadiazole. The computed optical absorption spectra of the designed compounds lie in the visible and near-infrared regions. Of all the studied copolymers, -CN substituted and Se-based compound displays the lowest HOMO-LUMO (E H - L) gap and optical band gap (E opt). The exciton binding energy (E b) is found to be smaller for O-incorporated compounds and -CN substituted copolymer as well, inferring more ICT. The electron-hole coherence concentrated over the D-A units is nearly the same for -CN and -NO2 substituted compounds, but larger in -F derivatives, indicating weak electron-hole coupling in the formers. Comparatively larger dipole moment (6.421 Debye-9.829 Debye) and charge transfer length (D CT) (1.976 Å-3.122 Å) for -CN derivatives lead to enhanced ICT properties. The designed donors yield good hole mobilities (0.127-6.61 cm2 V−1 s−1) and the predicted power conversion efficiencies are calculated to be as high as ~6%-7% for –CN and –NO2 substituted compounds. 相似文献
167.
G. S. Sahoo S. P. Tripathy S. Paul S. D. Sharma D. S. Joshi T. Bandyopadhyay 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(3):1289-1293
The neutron dose is estimated by linear energy transfer (LET) spectrometry method for two reactions, viz. 1H+9Be and 1H+12C at 20 MeV proton energy using CR-39 track detectors. The LET spectrum is generated from the major, minor radii of each track and thickness of removed surface from each side of the detector due to chemical etching. Microdosimetric distributions of absorbed dose and dose equivalents are obtained from the LET spectrum. The absorbed dose and dose equivalent per incident proton obtained from the LET spectra are found to be about 12.5 and 8 times higher in 1H+9Be reaction than 1H+12C reaction. 相似文献
168.
169.
Priyadarshini S. Sahoo Anuradha Panigrahi Sunanda K. Patri Rasm N. P. Choudhary 《Central European Journal of Physics》2010,8(4):639-642
A polycrystalline sample, Ba3Sr2DyTi3V7O30, with tungsten bronze structure was prepared by a mixed-oxide method at high temperature (950°C). Preliminary structural analysis of the compound showed an orthorhombic crystal structure at room temperature. Surface morphology of the compound was studied by scanning electron microscopy. The dielectric anomaly at 321°C may be attributed to the ferro-paraelectric phase transitions. This was also confirmed from the appearance of a hysteresis loop. The nature of variation of the ac conductivity and value of activation energy at different temperature regions, suggest that the conduction process is of mixed-type (i.e., ionic-polaronic and space charge generated from the oxygen ion vacancies). 相似文献
170.