全文获取类型
收费全文 | 1405篇 |
免费 | 50篇 |
国内免费 | 8篇 |
专业分类
化学 | 987篇 |
晶体学 | 12篇 |
力学 | 54篇 |
数学 | 155篇 |
物理学 | 255篇 |
出版年
2024年 | 5篇 |
2023年 | 21篇 |
2022年 | 43篇 |
2021年 | 59篇 |
2020年 | 55篇 |
2019年 | 62篇 |
2018年 | 55篇 |
2017年 | 38篇 |
2016年 | 59篇 |
2015年 | 47篇 |
2014年 | 61篇 |
2013年 | 145篇 |
2012年 | 117篇 |
2011年 | 87篇 |
2010年 | 70篇 |
2009年 | 53篇 |
2008年 | 54篇 |
2007年 | 46篇 |
2006年 | 53篇 |
2005年 | 31篇 |
2004年 | 35篇 |
2003年 | 27篇 |
2002年 | 21篇 |
2001年 | 21篇 |
2000年 | 21篇 |
1999年 | 15篇 |
1998年 | 7篇 |
1997年 | 9篇 |
1996年 | 4篇 |
1995年 | 10篇 |
1994年 | 12篇 |
1992年 | 4篇 |
1989年 | 5篇 |
1987年 | 9篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1974年 | 10篇 |
1971年 | 4篇 |
1960年 | 5篇 |
1959年 | 3篇 |
1958年 | 2篇 |
排序方式: 共有1463条查询结果,搜索用时 171 毫秒
951.
Design of a Simple Integrated Coupler for SPP Excitation in a Dielectric Coated Ag Thin Film
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A simple integrated coupler is proposed for the efficient excitation of surface plasmon polariton (SPP) mode in a thin metal film. The SPP mode is generated in a single Ag-dielectric interface by the incident field and coupled with an Ag thin film. The coupling efficiency at different wavelengths using two different dielectrics, gallium lanthanum sulfide (GLS) and aluminum gallium arsenide (AIGaAs) is calculated by analyzing the SPP propagation dynamics with the finite difference time domain method. A maximum coupling efficiency of 70~ is obtained at a wavelength of 46Ohm when GLS is used, whereas the corresponding value obtained for A1GaAs is 60~o at 56Onto. The proposed structure can be used to excite SPPs in a nano-thin film from an external bulky source and is easier to fabricate since a single interface metal-dielectric configuration is used to excite the metal-thin film. 相似文献
952.
S. Zia M. Amin U. Manzoor A. S. Bhatti 《Applied Physics A: Materials Science & Processing》2014,115(1):275-281
We demonstrate the synthesis, characterization and application of pure and tin (Sn) doped zinc oxide (ZnO) nanostructures with unique optical properties. Pencil-shaped nanorods were synthesized using a mixture of pure ZnO and carbon as starting material. The growth mechanism of these nanorods is discussed in detail. Sn-doped ultra-long belt-shape ZnO structures show many different colors in a single belt under fluorescent light in an optical microscope. These different colors are attributed to the presence of different defects in the ZnO lattice. X-ray diffraction and UV–VIS spectroscopy results are in good agreement with each other. A major application for these belts is likely to be in a single-particle sensor. A single belt based UV sensor is also fabricated and the results suggest that these photoconducting belts can serve as highly sensitive UV-light detectors. 相似文献
953.
Abadie J Abbott BP Abbott R Abernathy M Accadia T Acernese F Adams C Adhikari R Ajith P Allen B Allen GS Ceron EA Amin RS Anderson SB Anderson WG Antonucci F Arain MA Araya MC Aronsson M Arun KG Aso Y Aston SM Astone P Atkinson D Aufmuth P Aulbert C Babak S Baker P Ballardin G Ballmer S Barker D Barnum S Barone F Barr B Barriga P Barsotti L Barsuglia M Barton MA Bartos I Bassiri R Bastarrika M Bauchrowitz J Bauer TS Behnke B Beker MG Belletoile A Benacquista M Bertolini A Betzwieser J 《Physical review letters》2011,107(27):271102
The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. Finding no evidence to support the detection of GWs, we present 90% confidence level (C.L.) upper-limit maps of GW strain power with typical values between 2-20×10(-50) strain(2)?Hz(-1) and 5-35×10(-49) strain(2)?Hz(-1)?sr(-1) for pointlike and extended sources, respectively. The latter result is the first of its kind. We also set 90% C.L. limits on the narrow-band root-mean-square GW strain from interesting targets including Sco X-1, SN 1987A and the Galactic center as low as ≈7×10(-25) in the most sensitive frequency range near 160 Hz. 相似文献
954.
955.
Mathematical modeling of methane-fed anode-supported micro-tubular solid-oxide fuel cell (MT-SOFC) is developed. Steam reforming
of methane is considered in two cases of: direct internal reforming (DIR) and gradual internal reforming (GIR). The polarization
curves and temperature distribution of a cell fed with three variations of fueling (i.e., DIR and GIR of methane and pure
hydrogen) are compared with each other. The simulation results are verified through temperature and performance measurements
of a MT-SOFC sample operating on above three variations of fueling. In DIR operating condition, a drop in the anode gas temperature
at a short distance after entering the cell takes place which results in high temperature gradient. In GIR operating condition,
the temperature distribution in axial direction is steadier. The ohmic loss is lower in the case of pure hydrogen fuel than
internal reforming of methane, but the concentration loss is lower in methane-fed operating conditions. 相似文献
956.
A series of 2,3-dihydroquinazolin-4(1H)-ones have been synthesized in good to excellent yields through direct cyclocondensation of anthranilamide and aryl aldehydes or ketones in water or methanol under mild conditions.The reaction was efficiently promoted by 10 mol%sulfamic acid(SA,H2NSO3H) and the catalyst could be recovered easily after the reactions and reused without evident loss of reactivity. 相似文献
957.
The aim of this work was to devise a one‐step purification procedure for monoclonal antibodies (MAbs) of IgG class by immobilized metal affinity chromatography (IMAC). Therefore, several stationary phases were prepared containing immobilized metal chelates in order to study the chromatographic behaviour of MAbs against wild‐type amidase from Pseudomonas aeruginosa. Such MAbs adsorbed to Cu(II), Ni(II), Zn(II) and Co(II)–IDA agarose columns. The increase in ligand concentration and the use of longer spacer arms and higher pH values resulted in higher adsorption of MAbs into immobilized metal chelates. The dynamic binding capacity and the maximum binding capacity were 1.33 ± 0.015 and 3.214 ± 0.021 mg IgG/mL of sedimented commercial matrix, respectively. A KD of 4.53 × 10−7 m was obtained from batch isotherm measurements. The combination of tailor‐made stationary phases of IMAC and the correct selection of adsorption conditions permitted a one‐step purification procedure to be devised for MAbs of IgG class. Culture supernatants containing MAbs were purified by IMAC on commercial‐Zn(II) and EPI‐30–IDA–Zn(II) Sepharose 6B columns and by affinity chromatography on Protein A‐Sepharose CL‐4B. This MAb preparation revealed on SDS–PAGE two protein bands with Mr of 50 and 22 kDa corresponding to the heavy and light chains, respectively. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
958.
Antimony trisulphide (Sb2S3) films were prepared by thermal evaporation technique on n-type single crystal Si substrates to fabricate p-Sb2S3/n-Si heterojunctions. The electrical transport properties of the p–Sb2S3/n-Si heterojunctions were investigated by current–voltage (I–V) and capacitance–voltage (C–V) measurements. The temperature-dependent I–V characteristics revealed that the forward conduction was determined by multi-step tunnelling current and the activation energy of saturation current was about 0.54 eV. The 1/C2–V plots indicated the junction was abrupt and the junction built-in potential was 0.6 V at room temperature and decreased with increasing temperature. The solar cell parameters have been calculated for the fabricated cell as Voc = 0.50 V, Jsc = 14.53 mA cm−2, FF = 0.32 and η = 4.65% under an illumination of 50 mW cm−2. 相似文献
959.
This work aims at evaluating the mechanical behavior of sisal fiber reinforced cement mortar. The composite material was produced from a mixture of sand, cement, and water. Sisal fibers were added to the mixture in different lengths. Mechanical characterization of both the composite and the plain mortar was carried out using three point bend, compression, and impact tests. Specimens containing notches of different root radii were loaded in three point bending in an effort to determine the effect of the fibers on the fracture toughness of the material. The results obtained indicate that, while fiber reinforcement leads to a decrease in compressive strength, J-integral calculations at maximum load for the different notch root radii have indicated, particularly for the case of long fibers, a significant superiority of the reinforced material in comparison with the plain cement mortar, in consistence with the impact test data. 相似文献
960.
Abdol. R. Hajipour Amin Zarei Leila Khazdooz Seied A. Pourmousavi Bi Bi F. Mirjalili A. E. Ruoho 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):2029-2034
Direct sulfonylation of aromatic rings with aryl or alkyl sulfonic acid supported P2O5/Al2O3 (w/w 50%) under heterogeneous conditions in short reaction time and high yields. 相似文献