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Fei Lu Ding Yi Shoujie Liu Fei Zhan Bo Zhou Lin Gu Dmitri Golberg Xi Wang Jiannian Yao 《Angewandte Chemie (International ed. in English)》2020,59(40):17712-17718
A dual‐site catalyst allows for a synergetic reaction in the close proximity to enhance catalysis. It is highly desirable to create dual‐site interfaces in single‐atom system to maximize the effect. Herein, we report a cation‐deficient electrostatic anchorage route to fabricate an atomically dispersed platinum–titania catalyst (Pt1O1/Ti1?xO2), which shows greatly enhanced hydrogen evolution activity, surpassing that of the commercial Pt/C catalyst in mass by a factor of 53.2. Operando techniques and density functional calculations reveal that Pt1O1/Ti1?xO2 experiences a Pt?O dual‐site catalytic pathway, where the inherent charge transfer within the dual sites encourages the jointly coupling protons and plays the key role during the Volmer–Tafel process. There is almost no decay in the activity of Pt1O1/Ti1?xO2 over 300 000 cycles, meaning 30 times of enhancement in stability compared to the commercial Pt/C catalysts (10 000 cycles). 相似文献
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“能量”是学生认识化学变化的重要维度,本实验借助手持红外热成像仪“看到”化学反应中的能量变化。在实验中通过拍摄等量的不同酸溶液与氢氧化钠溶液混合反应时的热成像图,从“温度”高低间接反映出热量变化,从宏观的能量变化建立模型,推理微观的成键、断键等过程,探究酸碱中和反应过程的放热以及弱酸电离过程的吸热,并培养学生的证据推理能力和科学探究意识。 相似文献
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在物理实验教学中,教师通过对实验的改进优化、比较分析、探索探究和创新设计,可以达到对学生思维的求异性、类比性、深刻性和发散性的培养的作用.本文主要对实验教学过程中如何培养学生的创新思维能力谈谈体会· 相似文献
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一个创新网络动态性的仿真模型 总被引:2,自引:0,他引:2
李金华 《数学的实践与认识》2008,38(10):13-21
提出了一个关于创新网络动态性研究的仿真模型,模型较为全面地考察了网络的形成过程和不同的角色在创新和网络中的作用,研究结论指出:网络的形成是由于创新主体为适应创新的复杂性而寻求资源互补效应的动态相互作用的结果,中小型企业的个体在网络演化的早期和中期起了重要的作用,合作体的作用主要发挥在中后期. 相似文献
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针对惯例复制过程中与外部情景难以匹配的复制困境,分析了常规惯例复制和柔性惯例复制对知识转移的单独以及联合作用的关系悖论,对比分析作用机制在网络闭合性和环境不确定性约束下的权变性影响。以研发密集型企业为对象,运用多元回归分析进行实证检验。结果表明:网络闭合性和环境不确定性是惯例复制对知识转移的单独以及联合作用的权变条件;网络闭合性强化了常规惯例复制机制的促进作用,但限制了柔性惯例复制机制的效能发挥;环境不确定性削弱了常规惯例复制机制的促进作用,对柔性惯例复制机制的作用效果不显著;网络闭合性低或环境不确定性低时,两种惯例复制机制的联合作用相互补充,而网络闭合性高或环境不确定性高时,两种惯例复制机制相互替代。研究结论有助于揭示惯例复制的权变作用,对提升技术创新网络的知识转移效率具有重要意义。 相似文献
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Arun S. Mujumdar 《Transport in Porous Media》2007,66(1-2):3-18
Over the past three decades there has been nearly exponential growth in drying R&D on a global scale. Although thermal drying
had always been the workhorse of almost all major industrial sectors, the need for and opportunities in basic as well as industrial
research became clear only after the energy crisis of the early 1970s. Although the price of oil did drop subsequently the
awareness of the significance of improving the drying operation to save energy, improve product quality as well as reduce
environmental effect remained and indeed has flourished over recent years. New drying technologies, better operational strategies
and control of industrial dryers, as well as improved and more reliable scale-up methodologies have contributed to better
cost-effectiveness and better quality dried products. Yet there is no universally or even widely applicable drying theory
on the horizon. Most mathematical models of drying remain product-equipment specific for a variety of reasons. In this paper,
we examine the role of innovation in drying in various industrial sectors, e.g. paper, wood, foods, agriculture, waste management,
etc. Progress made over the past three decades and the challenges ahead are outlined. Some areas in need of further research
are identified. Examples of intensification of innovation in dryer designs via mathematical modeling are discussed. Finally,
the need for closer interaction between academia and industry is stressed as the key to successful drying R&D in the coming
decade. 相似文献
30.
Near infrared (NIR) spectrometry was used for the rapid characterization of quality parameters in desi chickpea flour (besan). Partial least square regression, principal component regression (PCR), interval partial least squares (iPLS), and synergy interval partial least squares (siPLS) were used to determine the protein, carbohydrate, fat, and moisture concentrations of besan. Spectra were collected in reflectance mode using a lab-built predispersive filter-based instrument from 700 to 2500?nm. The quality parameters were also determined by standard methods. The root mean square error (RMSE) for the calibration and validation sets was used to evaluate the performance of the models. The correlation coefficients for moisture, fat, protein, and carbohydrates in chickpea flour exceeded 0.96 using PLS and PCR models using the full spectral range. Wavelengths from 2100 to 2345?nm had the lowest RMSE for quality parameters by iPLS. The error was further decreased by 0.41, 0.1, and 1.1% for carbohydrates, fats, and proteins by siPLS. The NIR spectral regions yielding the lowest RMSE of prediction were 1620–2345?nm for carbohydrates, 1180–1590?nm and 1860–2094?nm for fat, and 1700–2345?nm for proteins. The study shows that chickpea flour quality parameters were accurately determined using the optimized wavelengths. 相似文献