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181.
Chemically modified zeolite Y (NaY) particles and their resulting modified electrodes were prepared with acridinium (AcH+), iron(II) and 1,10‐phenanthroline (phen) for energetic studies. According to diffuse reflectance absorption spectroscopy and cyclic voltammetry, AcH+ and Fe(phen)32+ were successfully entrapped in the zeolite particles. Transient emission spectra measurements showed that the life time of AcH+* in the zeolite particles (to 35 ns; λex 365 nm; λem 500 nm) was greatly reduced upon incorporating Fe(phen)32+ and Fe2+. The fast de cay of AcH+*(NaY) suggested that a reductive quench was likely to take place in the zeolite particle. Probably due to a size‐exclusion effect, the bulky electron donor, N, N‐diethyl‐2‐methyl‐1,4‐phenylenediamine (DEPD), revealed a difficulty in reaching the photosensitizer, AcH+, in side the zeolite particle. As a consequence, the in significant photocurrent for the oxidation of DEPD was from the NaY|AcH+ electrode. However, if Fe2+ and Fe(phen)32+ were incorporated, the photocurrent would become more significant. Closer examinations, in addition, showed that the photooxidaton of DEPD occurred more rapidly on the NaY|AcH+|Fe(phen)32+ electrode, compared to the NaY|AcH+|Fe2+ electrode. This difference apparently results from a greater gap in energetics between DEPD and Fe(phen)33+(NaY) than that between DEPD and Fe3+(NaY). Due to this effect, a greater amount of indophenol blue, derived from the coupling reaction of the oxidized DEPD with 1‐naphthol, was formed and de posited on the NaY|AcH+|Fe(phen)32+modified electrode. Thanks to this photo‐induced charge‐transfer reaction, the NaY|AcH+|Fe(phen)32+ particle showed an application potential in image recording. 相似文献
182.
Synthesis and characterisation of chemically crosslinked N-vinyl pyrrolidinone (NVP) based hydrogels
Declan M. Devine 《European Polymer Journal》2005,41(6):1272-1279
Crosslinked complexes of polyvinyl pyrrolidinone-polyacrylic acid (PVP-PAA) were prepared from a mixture of NVP, AA and ethyleneglycol dimethacrylates. The FTIR spectra of PVP-PAA copolymer complexes indicates both hydrogen bonded and non-hydrogen bonded PVP. Swelling of the PVP-PAA complex in a higher pH medium is significantly different from results in low pH solutions. Above the critical pH of the copolymer the carboxylic acid group of AA ionize. Therefore there is a reduction in the intermolecular bonding and so the hydrogels tend to swell to a greater degree yielding higher ‘water content’ and ‘water uptake’ values. The rheometry results indicated that there was a significant difference in the comparative gel strength at different pHs due to the increased water uptake. It was also found that by varying the molecular weight of the crosslinking agent an increase in comparative gel strength could be achieved. 相似文献
183.
C60敏化的顺 1,4 聚丁二烯的光氧化周涛陈双基(信阳师范学院化学系河南464000)(北京大学分校化学系北京100083)李子臣周锡煌李福绵(北京大学化学系北京100871)关键词C60,顺 1,4 聚丁二烯,光氧化自从能以宏观量制备C60... 相似文献
184.
Determination of Levamisole in Sheep Muscle Tissue by High-Performance Liquid Chromatography and Photo Diode Array Detection 总被引:1,自引:0,他引:1
A high-performance liquid chromatographic method for the determination of levamisole (LVM) residues in sheep muscle tissue
is described. LVM was extracted with ethyl acetate under alkaline conditions and cleanup was performed by liquid-liquid partition
between organic-basic and organic-acid medium. Finally, levamisole was back extracted with chloroform carefully transferred
into a clean glass vial and evaporated to dryness at 50 °C under a gentle stream of nitrogen. The remaining dry residue was
dissolved in the mobile phase used, filtered and an aliquot was injected automatically into the chromatograph for analysis.
Chromatography was performed on a Zorbax?SB-C18 column at 50 °C and detection by a PDA detector monitored at λmax 220 nm. The mobile phase was a mixture of 0.1 % trifluoroacetic acid (v/v) pH 2.0 and acetonitrile-methanol 3 : 2 (v/v) in a combination of 30 : 70 (v/v) and a flow rate of 1.0 mL min−1, delivered isocratically. This analytical method was validated by assessing recovery efficiency using spiked muscle tissue
samples with standard solutions in methanol at four fortification levels of 1/2 MRL, 1 MRL, 2 MRL and 4 MRL and five times
for each concentration (n = 5). Mean recovery (R%) achieved for muscle tissue was 75.65 ± 2.74% with an acceptable Relative Standard Deviation RSD%
= 10.4. The same method was used also for the analysis of kidney, liver and fat (perirenal) and the recoveries found were
70.25 ± 1.07% (RSD% = 1.52), 72.37 ± 3.6% (RSD% = 4.97) and 69.44 ± 2.22% (RSD% = 3.19), respectively. The limit of detection
(LOD) for muscle tissue was found to be 2.0 μg kg−1 and the limit of quantification (LOQ) 5.0 μg kg−1.
Revised: 4 and 24 January 2006 相似文献
185.
Experimental analysis and optimization of a photo resist coating process for photolithography in wafer fabrication 总被引:3,自引:0,他引:3
This investigation is applied the Taguchi method and combination the analysis of variance (ANOVA) to the photo resist (PR) coating process for photolithography in wafer manufacturing. Plans of experiments via nine experimental runs are based on the orthogonal arrays. In this study, the thickness mean and the uniformity of thickness of the PR are adopted as the quality targets of the PR coating process. This partial factorial design of the Taguchi method provides an economical and systematic method for determining the applicable process parameters. Furthermore, the ANOVA prediction of the thickness mean and the uniformity of thickness for the PR has been applied in terms of the PR temperature, chamber humidity, spinning rate, and dispensation rate by means of the designs of experiments (DOE) method. The PR temperature and the chamber humidity are found to be the most significant factors in both the thickness mean and the uniformity of thickness for a PR coating process. Finally, the sensitivity study of optimum process parameters was also discussed. 相似文献
186.
The Photo‐Dehydro‐Diels–Alder (PDDA) reaction is shown to be a versatile method for the preparation of highly functionalized naphthalenes. Thus, ketones 1 could be cyclized to the 1H‐benzo[g]isochromen‐4‐(3H)‐ones 11 and 12 , mostly in good yields. The influence of various substituents on the regioselectivity of the reaction was investigated, and the mechanism is discussed based on theoretical calculations. 相似文献
187.
188.
189.
Cu/ZnO-NiO上光促表面催化二氧化碳和水反应规律的研究 总被引:9,自引:0,他引:9
采用溶胶-凝胶法制备出摩尔分数为0.5%Cu/ZnO-1.5%NiO的n-p复合半导体材料,利用XRD,TEM,IR,UV-Vis和TPD技术对材料结构、吸光性能和化学吸附性能进行了表征,研究了该材料上CO2和H2O的光促表面催化反应(PSSR)规律.结果表明,所制备的材料能够明显促进PSSR的进行,室温条件下即有CH3OH,CH4和CO生成.讨论了温度对PSSR的影响规律.根据实验结果,得出CO2在材料表面的剪式和卧式吸附态分别为CH4和CH3OH的前驱物,并对PSSR机理进行了讨论. 相似文献
190.
端基含己氧基偶氮苯基元的一代光致变色液晶碳硅烷树状物的光响应行为研究 总被引:2,自引:0,他引:2
研究了端基含己氧基偶氮苯基元新的一代碳硅烷光致变色液晶树状物G1及其偶氮基元化合物M3在各种溶液中的反顺光异构化反应速率常数、光回复异构化反应速率常数、热回复异构化反应速率常数、量子产率、活化能和异构转换率.G1和M3的光致变色速率常数为0.1s-1,比对应的光致变色液晶聚硅氧烷的光响应速度快107倍. 相似文献