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921.
922.
用激光头和光敏电阻相结合进行人物进出计数功能;用温湿度传感器DHT11进行室内温湿度精确测量与温湿度超出预定值后自动将窗口打开关闭实现通风散热功能;用指纹模块识别收发室值班人员;用五路火焰传感器制作火灾报警系统。 相似文献
923.
Enhanced Electrochromism with Rapid Growth Layer‐by‐Layer Assembly of Polyelectrolyte Complexes
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Mengqi Cui Wee Siang Ng Xu Wang Peter Darmawan Pooi See Lee 《Advanced functional materials》2015,25(3):401-408
In this work, a facile method to deposit fast growing electrochromic multilayer films with enhanced electrochemical properties using layer‐by‐layer (LbL) self‐assembly of complex polyelectrolyte is demonstrated. Two linear polymers, poly(acrylic acid) (PAA) and polyethylenimine (PEI), are used to formulate stable complexes under specific pH to prepare polyaniline (PANI)/PAA‐PEI multilayer films via LbL deposition. By introducing polymeric complexes as building blocks, [PANI/PAA‐PEI]n films grow much faster compared with [PANI/PAA]n films, which are deposited under the same condition. Unlike the compact [PANI/PAA]n films, [PANI/PAA‐PEI]n films exhibit porous structure that is beneficial to the electrochemical process and leads to improved electrochromic properties. An enhanced optical modulation of 30% is achieved with [PANI/PAA‐PEI]30 films at 630 nm compared with the lower optical modulation of 11% measured from [PANI/PAA]30 films. The switching time of [PANI/PAA‐PEI]30 films is only half of that of [PANI/PAA]30 films, which indicates a faster redox process. Utilizing polyelectrolyte complexes as building blocks is a promising approach to prepare fast growing LbL films for high performance electrochemical device applications. 相似文献
924.
Transition‐Metal‐Free Magnesium‐Based Batteries Activated by Anionic Insertion into Fluorinated Graphene Nanosheets
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Considering resource abundance, high volumetric energy density, and safer anodic electroplating, the Mg‐based battery is thought to be one of the most promising systems beyond current Li‐ion batteries. However, the development of Mg batteries is hindered by the narrow electrochemical window of electrolytes as well as by inapplicable cathode frameworks. In this work, it is proposed, for the first time, to utilize a fast surface redox process to replace sluggish lattice migration for improving the kinetics of Mg batteries. Taking fluorinated graphene nanosheets (FGSs) as model material, a reversible capacity higher than 100 mAh g?1 is achieved in a pseudocapacitance behavior from 2.75 to 0.5 V. Different from traditional storage mechanisms, this proof‐of‐concept Mg/FGS system is activated by a prior anionic process followed by reversible cationic storage. The dilution of charge density by forming large‐sized monovalent complex cations and the easy access to surface redox sites are responsible for the negligible voltage polarization without an evident MgF2 nucleation phenomenon. 相似文献
925.
研究了一种基于紫外厚胶SU-8的亚毫米探针的加工工艺,通过溶液间的界面张力形成微球,再由深紫外光刻形成微柱。这种新技术利用紫外LIGA技术替代较为复杂昂贵的深反应离子刻蚀(DRIE)技术,使用甘油补偿紫外胶与空气之间的折射率差,使紫外光透过微球后依然可以曝光厚达几百微米SU-8胶形成微柱,并且提出原位放大接触点的对准方法,实现了微球与微柱的同轴。最终实现高深宽比的探针结构,可以作为关键部件应用于三坐标测量机。由于此工艺与传感器工艺相容,探针可以直接制作在集成了传感器的测头基底上,大幅减少了装配误差。 相似文献
926.
Xiangyu Cui Li Duan Jiaan Yan 《The Journal of the Operational Research Society》2015,66(10):1646-1655
Investigating the inverse problem of the classical Markowitz mean-variance formulation: Given a mean-variance pair, find initial investment levels and their corresponding portfolio policies such that the given mean-variance pair can be realized, we reveal that any mean-variance pair inside the reachable region can be achieved by multiple portfolio policies associated with different initial investment levels. Therefore, in the mean-variance world for a market of all risky assets, the common belief of monotonicity: ‘The larger you invest, the larger expected future wealth you can expect for a given risk (variance) level’ does not hold, which stimulates us to extend the classical two-objective mean-variance framework to an expanded three-objective framework: to maximize the mean and minimize the variance of the final wealth as well as to minimize the initial investment level. As a result, we eliminate from the policy candidate list the set of pseudo efficient policies that are efficient in the original mean-variance space, but inefficient in this newly introduced three-dimensional objective space. 相似文献
927.
928.
929.
射电精细结构是太阳爆发动态频谱图中一个重要的观测现象。为了达到更好提取精细结构轮廓,解读物理信息的目的。基于国家天文台怀柔观测站的2.6~3.8GHz频谱仪于2002年4月21日观测到的爆发现象,采用Levelset方法并加以改进,对原始图像进行轮廓提取,克服了以往此方法中存在遗漏检测的问题。此外对图像进行循环检测,取得了良好地检测结果。此后又对图像进行二值化提取,得到了二值化精细结构图像。最终统计出精细结构漂移率这一重要物理信息,为更好的理解太阳爆发机制提供了依据。 相似文献
930.
Yating Liu Yunhai Liu Xiaohong Cao Rong Hua Youqun Wang Cui Pang Ming Hua Xiaoyan Li 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(2):231-239
The cross-linked chitosan (CS) gels synthesized by using glutaraldehyde (GLA), epichlorohydrin (EC), and ethylene glycol diglycidyl
ether (EGDE) as cross-linkers respectively were used to investigate the adsorption of U(VI) ions in an aqueous solution. The
pure chitosan (PCS) and the cross-linked chitosan gels were characterized by FTIR and SEM analysis. The kinetic, thermodynamic
adsorption and adsorption isotherms of U(VI) ions onto unmodified and modified cross-linked chitosan were studied in a batch
adsorption experiments. The effect of pH, contact time and temperature on the adsorption capacity were also carried out. At
the optimum pH, the maximum adsorbed amount of PCS, GLACS, ECCS and EGDECS were 483.05, 147.05, 344.83 and 67.56 mg/g, respectively.
The uranium (VI) adsorption process of PCS and ECCS followed better with pseudo-second-order kinetic model, while GLACS and
EGDECS followed pseudo-first-order kinetic model well. The results obtained from the equilibrium isotherms adsorption studied
of U(VI) ions were analyzed in two adsorption models, namely, Langmuir and Freundlich isothms models, the results showed that
the Langmuir isotherm had better conformity to the equilibrium data. The thermodynamic parameters such as enthalpy (ΔHo), entropy (ΔSo), and Gibbs free energy (ΔGo) showed that the adsorption process was both spontaneous and endothermic. 相似文献