全文获取类型
收费全文 | 396篇 |
免费 | 21篇 |
国内免费 | 9篇 |
专业分类
化学 | 295篇 |
晶体学 | 1篇 |
力学 | 14篇 |
数学 | 33篇 |
物理学 | 83篇 |
出版年
2023年 | 1篇 |
2022年 | 8篇 |
2021年 | 16篇 |
2020年 | 19篇 |
2019年 | 16篇 |
2018年 | 19篇 |
2017年 | 10篇 |
2016年 | 19篇 |
2015年 | 14篇 |
2014年 | 21篇 |
2013年 | 44篇 |
2012年 | 38篇 |
2011年 | 36篇 |
2010年 | 28篇 |
2009年 | 19篇 |
2008年 | 25篇 |
2007年 | 17篇 |
2006年 | 21篇 |
2005年 | 11篇 |
2004年 | 9篇 |
2003年 | 5篇 |
2002年 | 8篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
排序方式: 共有426条查询结果,搜索用时 46 毫秒
121.
Badrnezhad Ramin Pourfarzad Hamed Madram Ali Reza Ganjali Mohammad Reza 《Russian Journal of Electrochemistry》2019,55(4):272-280
Russian Journal of Electrochemistry - The present paper aims to compare the corrosion protection performance of electrodeposited Ni?P with Ni–P–C nanocomposite coatings in 3.5 wt... 相似文献
122.
Using Ag nanoparticles on basalt fibers as a thermal and chemical resistant surface is a novel method for Suzuki coupling reactions. The characterization of this catalyst was done with various analytical tools. It was used as a heterogeneous catalyst and separated from the reaction medium easily. Also, it is economically advantageous, and we use it several times without reducing its catalytic activity. 相似文献
123.
Ramin Okhrati 《Applied Mathematical Finance》2019,26(2):101-130
We investigate hedging the risk of delayed data in certain defaultable securities through the local risk minimization approach. From a financial point of view, this indicates that in addition to the risk of default, investors also face incomplete accounting data. In our analysis, the delay is modelled by a random time change, and different levels of information, including the full market’s, management’s, and investors’ information, are distinguished. We obtain semi-explicit solutions for pseudo locally risk minimizing hedging strategies from the perspective of investors where the results are presented according to the solutions of partial differential equations. In obtaining the main results of this paper, we apply a filtration expansion theorem that determines the canonical decomposition of stopped special semimartingales in an enlarged filtration of investors’ information. 相似文献
124.
125.
Narges Oliyaei Aboulfazl Barati Taghi Miri 《Journal of Macromolecular Science: Physics》2015,54(7):761-770
Concentrated suspensions of sulfonated polyacrylamide (SPA)/Na+-montmorillonite (Na-MMT) were prepared and their stability and steady shear rheological properties were described as a function of nanoparticle and polymer concentration and temperature. The results showed that the Na-MMT nanoparticles suspensions were stable in the absence and presence of SPA and no sedimentation was seen. The Z-average particle sizes for the SPA/Na-MMT suspensions increased in the presence of SPA. Rheological investigations showed that the SPA solutions and SPA/Na-MMT suspensions displayed non-Newtonian behavior in almost the whole range of shear rate. All the suspensions exhibited a shear-thinning flow character as shear rate increased. The flow curves indicated the shear viscosity and stress of the samples were decreased with increasing nanoparticles concentration up to 1.5 wt%, but for Na-MMT loading greater than 1.5 wt% there was an increase in shear viscosity and stress of the suspensions. Increasing of SPA concentration had more effect on increasing the rheological properties of SPA/Na-MMT suspensions than increasing of nanoclay content. Shear viscosity and stress of the suspensions increased with increasing SPA concentration and decreased with increasing temperature from 50°C to 70°C. 相似文献
126.
Prussian blue modified carbon ionic liquid electrodes (PB‐CILEs) were fabricated using chemical and electrochemical procedures. Chemically fabricated PB‐CILE exhibited an excellent sensitivity (0.0866 μA μM?1), low detection limit (0.01 μM) and two linear ranges (0.01–1 and 1–600 μM) toward hydrogen peroxide. Then, glucose oxidase (GOx) was immobilized on the surface of PB‐CILE to fabricate glucose biosensor using three different procedures involving cross linking with glutaraldehyde (GLU) and bovine serum albumin (BSA), entrapment into the Nafion matrix and covering with a sol‐gel layer. Glucose biosensor fabricated using cross linking procedure showed the best sensitivity (0.0019 μA μM?1) and operational stability for glucose. 相似文献
127.
Maximum trapping efficiency in optical tweezers occurs close to the coverslip because spherical aberration owing to a mismatch in the refractive indices of the specimen (water) and the immersion oil dramatically decreases the trap efficiency as the trap depth increases. Measuring the axial trap efficiency at various tube lengths by use of an oil-immersion objective has shown that such an aberration can be balanced by another source of spherical aberration, leading to a shift in the position of the maximum efficiency in the Z direction. For a 1.1 microm polystyrene bead we could achieve the maximal efficiency at a depth of 70 microm, whereas the trap was stable up to a depth of 100 microm. 相似文献
128.
129.
Various aryl aldehydes underwent prompt one pot conversion into the corresponding nitriles in high yields by reacting with hydroxylamine hydrochloride supported on melamine formaldehyde under microwave irradiation in the presence of ammonium acetate as catalyst. 相似文献
130.
Irradiation (λ =313 nm) of the 4-pyrrolin-3-ones 1a–1c in acetone-, 3-pentanone-and cyclopentanone solution affords the title compounds 2 , formally via H-abstrac-tion by the excited ketone and recombination of the radical pair formed. 相似文献