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排序方式: 共有209条查询结果,搜索用时 31 毫秒
1.
Hua Zhang Nabil A. Amro Robert Elghanian Joseph Fragala 《Applied Surface Science》2006,253(4):1960-1963
A method, combining micro-contact printing (μCP), wet chemical etching and reactive ion etching (RIE), is reported to fabricate microstructures on Si and SiOx. Positive and negative structures were generated based on different stamps used for μCP. The reproducibility of the obtained microstructures shows the methodology reported herein could be useful in Micro-Electro-Mechanical Systems (MEMS), optical and biological sensing applications. 相似文献
2.
A.R. Phani 《Applied Surface Science》2006,253(4):1873-1881
The structural properties of fluorine containing polymer compounds make them highly attractive materials for hydro-oleophobic applications. However, most of these exhibit low surface energy and poor adhesion on the substrates. In the present investigation, crack free, smooth and uniform thin films of poly[4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole]-co-tetrafluoroethylene (TFD-co-TFE) with good adhesion have been deposited by wet chemical spin-coating technique on polished AISI 440C steel substrates. The as-deposited films (xerogel films) have been subjected to annealing for 1 h at different temperatures ranging from 100 to 500 °C in an argon atmosphere. The size growth of the nano-hemispheres increased from 8 nm for xerogel film to 28 nm for film annealed at 400 °C. It was found that as the annealing temperature increased from 100 to 400 °C, nano-hemisphere-like structures were formed, which in turn have shown increase in the water contact angle from 122° to 147° and oil (peanut) contact angle from 85° to 96°. No change in the water contact angle (122°) has been observed when the films deposited at room temperature were heated in air from 30 to 80 °C as well as exposed to steam for 8 days for 8 h/day indicating thermal stability of the film. 相似文献
3.
Eun-Ku Lee Kwang-Deog Jung Oh-Shim Joo Yong-Gun Shul 《Reaction Kinetics and Catalysis Letters》2004,83(1):25-30
The room temperature wet catalytic oxidation was conducted in a batch reactor with V/MgO catalyst. The XRD study of the catalyst
used indicated that V/MgO could not only oxidize H2S to sulfur selectively, but also prevent the sulfidation of metal oxide
effectively at the room temperature. The XPS study indicated that the H2S oxidation with V/MgO could proceed by a redox mechanism
(V5+↔ V4+) and that V3+ formation (V4+→ V3+), was responsible for the deactivation of V/MgO.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
4.
This paper mainly deals with the design and synthesis of a novel styrene-butadieneblock copolymer. When this copolymer is used in the tread portion of tyres, it can improvewet skid resistance and reduce rolling resistance without sacrificing its general physical-mechanical properties. The visco-elastic curve of tire tread using the novel copolymer asits rubber portion was showed. Reactivity ratios for two monomers in the polymerizingsystem were calculated. The diagrams of differelitial, integral and finite difference calculithroughout the whole molecular chain were presented. The influence of the micro- andmacro-structure of the copolymer chain on wet skid resistance and rolling resistance wasdiscussed 相似文献
5.
Mohammad Ali Zolfigol Khodabakhsh Niknam Mojtaba Bagherzadeh Arash Ghorbani‐Choghamarani Nadiya Koukabi Maryam Hajjami Eskandar Kolvari 《中国化学会会志》2007,54(5):1115-1118
Tribromoisocyanuric acid (TBCA) and Oxone®‐MX systems were used as effective oxidizing agents for the oxidation of thiols to their corresponding disulfides under mild conditions at room temperature with good to excellent yields. 相似文献
6.
The main approaches that have been taken to chemically modify polymer surfaces are introduced and reviewed. These are wet chemical oxidation, plasma treatment, classical organic chemistry, and attachment of polymer chains. The extent to which each of these approaches can produce the specific modifications desired is discussed, and any unwanted effects that commonly occur are cited. Finally, the need for using several methods of surface analysis in concert to obtain adequate surface characterization is described. 相似文献
7.
8.
利用湿法反应制备的LiV3O8的锂离子扩散特性 总被引:4,自引:0,他引:4
利用V2O5•nH2O湿凝胶和Li2CO3作原料,通过溶液反应和低温焙烧的方法合成了用于锂离子电池正极的LiV3O8.对其前驱体和产品分别进行DTA-TG、XRD表征.LiV3O8用作锂离子电池正极的电化学性能利用恒电流充放电测试进行研究.实验表明活性材料LiV3O8具有较高的充放容量和良好的循环性能.LiV3O8电极的锂离子化学扩散系数由恒电位间歇滴定技术(PITT)来确定,其值依据Li1+xV3O8中x值的不同在10-8~10-10 cm2•s-1的变化范围内.获得的锂离子的扩散活化能为:Ea=25~42 kJ•mol-1(x=0.18~2.5).认为锂离子扩散的最大活化能是由锂离子在Li4V3O8相中的扩散决定的. 相似文献
9.
The High Pressure Asher (HPA-S) was adapted with a Teflon liner for pressurized wet digestion in open vessels. The autoclave was partly filled with water containing 5% (vol/vol) hydrogen peroxide. The digestion vessels dipped partly into the water or were arranged on top of the water by means of a special rack made of titanium or PTFE-coated stainless steel. The HPA-S was closed and pressurized with nitrogen up to 100 bars. The maximum digestion temperature was 250 °C for PFA vessels and 270 °C for quartz vessels. Digestion vessels made of quartz or PFA-Teflon with volumes between 1.5 mL (auto sampler cups) and 50 mL were tested. The maximum sample amount for quartz vessels was 0.5–1.5 g and for PFA vessels 0.2–0.5 g, depending on the material. Higher sample intake may lead to fast reactions with losses of digestion solution. The samples were digested with 5 mL HNO3 or with 2 mL HNO3+6 mL H2O+2 mL H2O2. The total digestion time was 90–120 min and 30 min for cooling down to room temperature. Auto sampler cups made of PFA were used as digestion vessels for GFAAS. Sample material (50 mg) was digested with 0.2 mL HNO3+0.5 mL H2O+0.2 mL H2O2. The analytical data of nine certified reference materials are also within the confidential intervals for volatile elements like mercury, selenium and arsenic. No cross contamination between the digestion vessels could be observed. Due to the high gas pressure, the diffusion rate of volatile species is low and losses of elements by volatilisation could be observed only with diluted nitric acid and vessels with large cross section. In addition, cocoa, walnuts, nicotinic acid, pumpkin seeds, lubrication oil, straw, polyethylene and coal were digested and the TOC values measured. The residual carbon content came to 0.2–10% depending on the sample matrix and amount. 相似文献
10.
Bo?AndreassonEmail author Jennie?Forsstr?m Lars?W?gberg 《Cellulose (London, England)》2005,12(3):253-265
It has been shown, in the present investigation, that the two methods used to investigate the pore size distribution of unbleached
chemical pulps, i.e. inverse size exclusion chromatography (ISEC) and nuclear magnetic resonance (NMR), give different average
pore radius for the pores inside the fibre wall. This is due to the way in which these experiments are performed and the sensitivity
of the methods to different types of pores in the cell wall. It was also shown that the two methods gave different results
when changing the pH and the ionic strength of the pulp suspension. The pore radius, as detected with ISEC, decreased with
both increasing ionic strength and decreasing pH, indicating a loose structure of the exterior of the fibrillar network. However,
the pore radius as detected with NMR, was virtually unaffected when increasing the ionic strength, indicating a very rigid
structure of the interior of the fibre wall. Decreasing pH though, lead to a decrease in pore radius indicating that upon
protonation of the carboxylic groups in the fibre wall, the electrostatic repulsion is diminished and the average pore radius
decreases. The NMR technique was also used to study wet strength aid penetration into the fibre wall. It was shown that wet
strength aids with a small molecular weight, penetrated the fibre wall, as detected by a decrease in pore radius. It was also
shown that addition of different wet strength aids increased the tensile index of the sheet and decreased the fibre strength,
measured as zero span-strength of the sheets. 相似文献