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71.
Formation of transmission holographic polymer dispersed liquid crystal gratings was studied for matrix components of trimethylolpropane
triacrylate:trimethoxysilylmethyl methacrylate:1-vinyl-2-pyrrolidone (reactive diluent) in the range from 80:10:10,wt% to
10:80:10,wt% and E7 as nematic liquid crystal under the irradiation with Nd-YAG laser (532,nm).
The optimum concentration of E7 in the recording solution was 35,wt% (65,wt% of matrix components) in presence of small amounts
of radical photo-initiator system (Rose Bengal 0.05,wt%, NPG 0.1,wt%). When the concentration of methacrylate in matrix components
was low (< 30%), gratings with apparently high diffraction efficiency could be fabricated both for trimethoxysilylmethyl methacrylate
(cross-linkable by hydrolysis) and trimethylsilylmethyl methacrylate (non-cross-linkable by hydrolysis), although transiently
high initial diffraction efficiency was observed by the non-equilibrium initial photo-polymerization of cross-linking components.
Distinct difference was seen at higher concentration (> 50,wt%) of the methacrylates. Contrary to that gratings with reasonably
high and stable diffraction efficiency were successfully fabricated with trimethoxysilylmethyl methacrylate, gratings with
only low diffraction efficiency were obtained for non-cross-linkable trimethylsilylmethyl methacrylate.
With higher concentration of photo-sensitizer and photo-initiator (0.2,wt%; 1.0,wt%), and shorter irradiation time, gratings
with high diffraction efficiency could be fabricated only for the photo-initiator system of 3,3′-carbonylbis(7-diethylaminocoumarin)
and diphenyliodonium hexafluorophosphate with shorter induction period (∼174,s).
Grating with diffraction efficiency of 72% was obtained with trimethoxysilylpropyl acrylate (80,wt% in the matrix component)
and 35,wt% E7. By increasing the concentration of diphenyliodonium hexafluorophosphate to 2,wt%, diffraction efficiency increased
to 85% and induction period was shortened to 129,s, and low volume shrinkage of 8% was attained via simultaneous radical cross-linking
of trimethylolpropane triacrylate and siloxane network formation of trimethoxysilyl groups of trimethoxysilylmethyl acrylate
by atmospheric moisture catalyzed by cationic species produced from the initiator system.
In SEM morphology, although gratings formed with high concentration of trimethoxysilylpropyl acrylate had some cracks in polymer
matrix, the largest grating spacing indicating the lowest volume shrinkage and very regular and well-defined gratings were
observed. 相似文献
72.
采用激光染料DCM、向列相液晶TEB30A、手性剂S-811、聚乙烯醇(PVA), 通过微胶囊法制备了聚合物分散胆甾相液晶薄膜, 测量激光辐射谱, 研究了其激光辐射机理和温度调谐特性. 利用正交偏光显微镜观察器件织构, 看到液晶微滴分散均匀, 尺寸较大, 约为80 μm, 并且微滴中液晶分子呈现平面态排列织构. 以532 nm的Nd:YAG固体激光器作为抽运源, 测得在634.5 nm和680.2 nm波长处出现了尖锐的激光辐射峰, 线宽分别约为0.25 nm, 0.29 nm. 并与染料掺杂胆甾相液晶激光器件进行比较. 升高器件温度, 其输出激光波长蓝移, 获得666.7 nm至643.9 nm共22.8 nm的调谐范围. 由实验结果分析得出, 激光辐射机理为光子禁带末端激光, 出射波长分别对应光子禁带的两个边沿. 相似文献
73.
建立了一整套Rh簇高分散催化剂的制备技术和方法,制备出了分散的Rh_2/Al_2O_3和Rh_4/Al_2O_3簇催化剂。H_2化学吸附表明这些样品具有很高的金属分散度,且分散度随Rh簇担载量的增加而降低。CO吸附态测定表明,当簇合物的Rh担载量(w%Rh)为0.7%时分散度最高。CO分子在催化剂上只有一种吸附方式─—孪生吸附,实现了CO吸附态的“分离”,即催化剂上只存在一种吸附中心。表明催化剂的金属粒度已达到均一。这一结果还表明可通过原子簇衍生催化剂的方法来控制CO分子在Rh催化剂上的吸附方式。催化剂制备过程的原位红外光谱测试结果表明:Rh簇与γ-Al_2O_3作用形成高分散是一个很快的过程。 相似文献
74.
Laurent?GaillonEmail author Juliette?Sirieix-Plenet Pierre?Letellier 《Journal of solution chemistry》2004,33(11):1333-1347
At room temperature, the 1-decyl-3-methylimidazolium bromide (DMImBr) is a long alkyl chain imidazolium ionic liquid miscible with water and forming a gel zone between 5 and 40% w/w H2O. We measured the density of the liquid mixtures of water and DMImBr. We determined the apparent molar volume of the molten salt for dilute solutions. For the concentrated solutions the partial molar volume of each component was evaluated by a perturbation method. These results are shown to be substantially different from those obtained with a short chain bromide ionic liquid, 1-butyl-3-methylimidazolium bromide (BMImBr). The amphiphilic ionic liquid (DMImBr) has been shown to form micelles and its critical micelle concentration (cmc) has been determined. Below the cmc, the Debye–Hückel limiting law for 1:1 electrolytes describes very accurately the behavior of low concentrations of the DMImBr salt in water. Above the cmc, the partial molar volume of the micellized monomer was approximately equal to the molar volume of the pure fused salt. The partial molar volume of water in these mixtures was similar to that of pure water. The concentrated solutions behave like mixtures of interpenetrated phases. 相似文献
75.
A. Sánchez A. Zapardiel F.López de Prado E. Bermejo M. Moreno J. A. Pérez‐López M. Chicharro 《Electroanalysis》2007,19(16):1683-1688
A new analytical methodology for the electrochemical detection of the herbicide maleic hydrazide (3,6‐dihydroxypyridazine) by flow injection analysis is presented. This method is supported by the novel application of a palladium‐dispersed carbon paste electrode as an amperometric sensor for this herbicide. Maleic hydrazide shows anodic electrochemical activity on carbon‐based electrodes (glassy carbon or carbon paste electrodes) in all the pH range. This electrochemical activity is enhanced using metal‐dispersed carbon paste electrodes, especially at Pd‐dispersed CPE which displays good oxidation signals at 690 mV (0.050 M phosphate buffer pH 7.0), 140 mV lower than at unmodified electrodes. Under the optimized conditions, the electroanalytical performance of Pd‐dispersed CPE in flow injection analysis was excellent, with good reproducibility (RSD 3.3%) and a wide linear range (1.9×10?7 to 1.0×10?4 mol L?1). A detection limit of 1.4×10?8 mol L?1 (0.14 ng maleic hydrazide) was obtained for a sample loop of 100 μL at a fixed potential of 700 mV in 0.050 M phosphate buffer solution at pH 7.0 and a flow rate of 2.0 mL min?1. The proposed method was applied for the maleic hydrazide detection in natural drinking water samples. 相似文献
76.
M. V. Tsodikov O. V. Bukhtenko O. G. Ellert I. A. Petrunenko A. S. Antsyshkina G. G. Sadikov Yu. V. Maksimov Yu. V. Titov V. M. Novotortsev 《Russian Chemical Bulletin》1995,44(8):1396-1400
Two new compounds have been obtained by the synthesis of heteronuclear iron-yttrium acetylacetonate, using the modified electrochemical dissolution of the [YFe2] alloy. One of these compounds, with the Fe(acac)2 · 2H2O composition, has been studied by X-ray diffraction analysis. X-ray diffraction data: a=11.002(5), b=5.412(2), c=11.179(5) Å;=106.39(4)°;V=638.6 Å3, space group P21/c, Z=2. According to the data on magnetic susceptibility, Mössbauer spectroscopy, and X-ray electron microanalysis, single crystals of this complex are covered with an amorphous film containing finely dispersed [Y1–aFea]n clusters and, probably, superparamagnetic -Fe2O3 species. The second oligomeric acetylacetonate complex contains ions of high-spin two-valence iron, yttrium, and finely dispersed ferromagnetic [Y1–aFea)n intermetallide clusters.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1454–1458, August, 1995.The studies were financially supported by the International Science Foundation (Grants Nos. MI 8000, MI 8300). 相似文献
77.
采用配有441.6 nm滤光片的光差示扫描量热仪研究了3,3'-羰基双(7-二乙胺香豆素)(KCD)/N-甲基二乙醇胺(MDEA)/2-(4-甲氧苯基)-4,6-双(三氯甲基)-1,3,5-三嗪(TA)三元引发剂引发丙烯酸酯/液晶复合体系光聚合动力学行为. 结果表明, 在KCD/MDEA复合引发剂中添加TA, 显著提高了丙烯酸酯/液晶复合体系的最大光聚合速率[Rp(max)]和单体转化率, 当TA质量分数为0.5%时, 体系的Rp(max)和单体转化率分别提高了100%和69%. 同时, 随着光照强度的增加, 该体系的Rp(max)和单体转化率呈增大的趋势, 当光强从1.5 mW/cm+2提高到35.2 mW/cm+2时, 其Rp(max)和最终单体转化率分别提高了2.5和2.8倍. 相似文献
78.
79.
G. Cipparrone A. Mazzulla F. P. Nicoletta L. Lucchetti F. Simoni 《Optics Communications》1998,150(1-6):297-304
We report a detailed investigation on holographic grating formation in dye-doped polymer dispersed liquid crystals. Both optical and scanning electron microscope measurements have been carried out. All the experimental data support the idea that a photorefractive-like effect is the basic mechanism of the optical storage effect, while it is demonstrated that neither droplets' size or shape effects, nor dye or polymer reorientation are involved in the process. 相似文献
80.
In this paper we develop an approach to design a three-phase, gas–solid–liquid flow system that transports pneumatically scarified solid particles, including sticky ones, through a vertical pipe. The proposed system permits the introduction and maintenance of a liquid film that coats the pipe’s inner wall and acts as a lubricant that ensures sticky particles continue to move upward without permanently adhering to the pipe wall. The system’s operating conditions fall within the boundaries of the annular dispersed region on a typical flow pattern map of vertical flow of a gas–liquid mixture. High gas superficial velocities combined with low liquid superficial velocities characterize such a region. A combination of a modified one-dimensional, two-fluid annular dispersed flow model and a one-dimensional pneumatic conveying model is shown to describe this transport process satisfactorily. Solution of the combined models produces all the necessary design parameters including power requirements and superficial velocities of the two-fluid media needed to transport a given amount of solid particles. Results of model calculations are compared with rare three-phase flow data obtained prior to the development of the present model, by an independent experimental team that used the physical conditions of the present approach. Reasonable agreement justifies the use of the combined model for engineering design purposes. 相似文献