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排序方式: 共有167条查询结果,搜索用时 31 毫秒
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对四川地区江河上数座水电站坝基砂层的26组动力三轴试验资料进行了统计分析,基于动剪应力比法的液化判别方法推导了的地震液化的极限状态方程,使用蒙特卡洛随机抽样的方法计算了砂层液化的失效概率,并对某水电站的厂房地基砂层的液化可靠度进行了计算分析。研究表明,统计按粉砂样总体和中细砂样总体划分较为合理;砂层的动剪应力比可采用正态分布;电站砂层地基地震液化的最危险工况为,闸坝盖重加稳定的向上渗流及遭遇Ⅶ度地震荷载,为高液化风险,其液化概率随埋深加大而增大,最危险部位为砂层底板,对坝基砂层应进行抗液化处理。 相似文献
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对从煤液化残渣中萃取出的沥青类物质进行了固体13C-CP/MAS NMR分析、元素分析、红外光谱分析(FT-IR)和光电子能谱(XPS)分析,得到煤液化沥青的芳香结构单元信息及相关结构参数信息。结果表明,煤液化沥青芳香桥碳与周碳之比为0.115,芳香碳原子的存在形式以苯结构为主;脂肪结构多以甲基和环状亚甲基形式存在;氧主要以羰基、酯基的形式存在;氮主要以吡咯的形式存在。利用结构参数和分析表征结果构建了煤液化沥青的大分子结构模型,并运用13C-NMR预测软件ACD/CNMR Predictor计算了煤精制沥青大分子结构模型的13C化学位移。根据计算结果对大分子结构模型进行了修正,获得了与实验谱图吻合较好的大分子结构模型。 相似文献
4.
以N-叔丁基-α-苯基硝酮(PBN)为自由基结合剂,采用间歇式高温高压反应釜对玉米秸秆纤维素进行超临界乙醇液化,考察PBN用量(浓度)和反应温度(活性)对纤维素液化产物及生物油中主要化合物分布的影响。结果表明,在320℃,仅有超临界乙醇作用,生物油收率为37.17%,挥发分收率高达50.08%;随着PBN用量增加到0.4 g,生物油收率最高提升至48.35%,挥发分最低下降到35.65%。在超临界乙醇和PBN作用下,随着反应温度从250℃升高至340℃,纤维素转化率从23.10%急剧增加至88.92%,生物油收率从19.18%上升到最高48.35%(320℃)后略有下降,挥发分也从6.03%急剧上升至50.28%。GC-M S结果显示,酯类、酮类、烃类、醇类、酸类及苯类化合物是生物油的主要成分,各组分的最高相对含量分别为27.91%、15.77%、13.44%、12.42%、16.07%、19.81%。实验结果证实了PBN对纤维素超临界乙醇液化产物及生物油组分分布产生了较明显的影响,尤其能通过与含苯基、乙基等活性碎片结合促进挥发分与生物油之间的转化,且PBN用量及液化温度的改变可以促使生物油中主要化合物发生不同程度的相互转化。 相似文献
5.
Cellulose liquefaction in acidified ethylene glycol 总被引:3,自引:0,他引:3
Wood pulp cellulose was used in a study of its catalyzed liquefaction in the presence of ethylene glycol, p-toluene sulfonic acid monohydrate or sulphuric acid being the catalysts. For this study, microcrystalline cellulose, Whatman
filter paper no. 1 and cotton linters with molar masses of 76,000, 699,000 and 1,910,000 g mol−1, respectively were used. This liquefaction was studied by gravimetric determinations, by X-ray diffraction analysis of the
residual cellulose and by monitoring of the molar mass decrease over different time intervals, using size-exclusion chromatography.
The disordered regions, even of cellulose with the highest molar mass degraded in the initial minute of liquefaction. However,
the highly ordered cellulose regions remained relatively stable for a longer time. None the less, partial degradation of the
highly ordered regions of the cellulose was achieved. 相似文献
6.
Summary Hydroaromatics (partially hydrogenated polycyclic aromatic hydrocarbons) generated in the course of the process play an important role in the catalytic hydroliquefaction of coal. A difficult analytical task is to identify and to quantify these hydroaromatics among the preponderant polycyclic aromatic hydrocarbons. Generally speaking, the method carried out uses the specific separation of hydroaromatic by charge transfer chromatography. Structural identification is effected by using gas chromatography, alone or coupled with mass spectrometry, and HPLC on amino bonded phase with UV detection.As an aid to obtaining the standard compounds that are essential in that work, this paper describes the application of the above analytical procedure to the catalytic hydrogenation products (RhCl3/NaBH4 and Pd/C) of benzo(a) and benzo(e)pyrenes. 相似文献
7.
This paper presents a micromechanical study on the behavior of granular materials under confined shear using a three-dimensional Discrete Element Method (DEM). We consider rotational resistance among spherical particles in the DEM code as an approximate way to account for the effect of particle shape. Under undrained shear, it is found rotational resistance may help to increase the shear strength of a granular system and to enhance its resistance to liquefaction. The evolution of internal structure and anisotropy in granular systems with different initial conditions depict a clear bimodal character which distinguishes two contact subnetworks. In the presence of rotational resistance, a good correlation is found between an analytical stress-force-fabric relation and the DEM results, in which the normal force anisotropy plays a dominant role. The unique properties of critical state and liquefaction state in relation to granular anisotropy are also explored and discussed. 相似文献
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Fei Yu Roger Ruan Xiangyang Lin Yuhuan Liu Rong Fu Yuhong Li Paul Chen Yinyu Gao 《Applied biochemistry and biotechnology》2006,130(1-3):563-573
The purpose of this research was to study the kinetics of liquefaction of crop residues. The liquefaction of corn stover in
the presence of ethylene glycol and ethylene carbonate using sulfuric acid as a catalyst was studied. It was found that the
liquefaction yield was a function of ratio of solvent to corn stover, temperature, residence time, and amount of catalyst.
Liquefaction of corn stover was conducted over a range of conditions encompassing residence times of 0–2.5 h, temperatures
of 150–170°C, sulfuric acid concentrations of 2–4% (w/w), and liquefaction reagent/corn stover ratio of 1–3. The liquefaction
rate constants for individual sets of conditions were examined using a first-order reaction model. Rate constant increased
with the increasing of liquefaction temperature, catalyst content, and liquefaction reagent/corn stover ratio. Reuse of liquefied
biomass as liquefying agent was also evaluated. When using recycled liquefied biomass instead of fresh liquefaction reagent,
the conversion is reduced. It appeared that 82% of liquefaction yield was achieved after two times of reuse. 相似文献