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A series of new o‐phenylenediamine (OPD)/o‐phenetidine (PHT) copolymers with partly phenazine‐like structures has been successfully synthesized at three polymerization temperatures by chemically oxidative polymerization in four different polymerization media. The molecular structures and properties of the resulting OPD/PHT polymers were investigated by IR, UV–vis and high‐resolution 1H NMR spectroscopies, and DSC, in order to ascertain the effect of reaction temperature, comonomer ratio and acid medium. The copolymerization mechanism of OPD with PHT monomers has been proposed. It is found that the statistical OPD/PHT copolymer obtained at a temperature of 118 °C has a higher degree of polymerization than that obtained at 12–17 °C. The OPD content in the copolymers calculated from NMR spectroscopic analysis is higher than that in the feed OPD content, whereas the OPD content calculated from element analysis is slightly lower than the feed OPD content. It can be predicted that denitrogenation takes place in the OPD units during the polymerization process at OPD/PHT molar ratios of 90/10 and 100/0. These OPD/PHT copolymers exhibit a much better solubility than the OPD homopolymer, hence suggesting an incorporation of PHT units into the phenazine structure of the homopolymer. The thermal behavior of the copolymers was also studied. Copyright © 2004 Society of Chemical Industry 相似文献
154.
Jun Rong Li Jun Wang Jia Rui Xu Ming Qiu Zhang Min Zhi Rong Qiang Zheng 《Composites Science and Technology》2006,66(16):3126-3131
The authors of this paper synthesized a series of amphiphilic triblock copolymers of polystyrene-b-poly(ethylene glycol)-b-polystyrene (PS-PEG-PS) having different PEG/PS ratios with nearly identical molecular weights of the entire copolymers. The interfacial interactions in the composites consisting of carbon black and the copolymers can thus be tailored. When these conducting composites are exposed to certain solvent vapors, their electrical resistances greatly increase, showing the gas sensitivity. The present work indicated that this switching behavior is controlled by the structural relaxation of the composites because matrix swelling acts as the main mechanism. The response time has been correlated with absolute temperature by Arrhenius equation, and the estimated activation energy reflects mobility of the fillers involved in the solvent induced expansion of the surrounding polymer. Therefore, by using the gas sensibility of the conductive composites, the structure evolution of the composite materials in solid state and the effect of filler/matrix interfacial interaction on the relaxation property of the matrix polymer has been inspected. It was found that lower activation energy represents stronger interfacial interaction in case good solvent of the matrix was used for the test. 相似文献
155.
设计了一种新结构的InGaAs/InP双异质结晶体管(DHBT),其中发射结采用δ掺杂和阻挡层结构,集电极采用N+掺杂复合结结构.考虑隧穿作用和发射结空间电荷区复合电流的影响,计算了δ掺杂浓度和N+、n-层厚度等参数变化对InGaAs/InP DHBT电流、I-V输出特性、电流增益的影响,计算结果表明,随着这些参数值增大,InGaAs/InP DHBT输出特性逐渐改善.当δ掺杂浓度大于2×1012cm-3时,电流增益趋于饱和. 相似文献
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157.
Guanghui Wang Lei Huang Rong Yu Nansheng Deng 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(5):601-608
BACKGROUND: Endocrine disruptors in the aquatic environment and their potential adverse effects are currently issues of concern. One of these endocrine disruptors is 2,2‐bis(4‐hydroxy‐3‐methylphenyl)propane (BPP). In this work the molecular recognition interaction of BPP with β‐cyclodextrin (β‐CD) was studied using IR spectroscopy and steady state fluorescence spectroscopy, and the photocatalytic degradation behaviour of BPP based on molecular recognition interaction was investigated in a TiO2/UV–visible (λmax = 365 nm) system. This might provide a new method for the treatment of some organic pollutants in wastewater. RESULTS: β‐CD reacts with BPP to form a 1:1 inclusion complex, the formation constant of which is 4.94 × 103 L mol?1. The photodegradation rate constant of BPP after molecular recognition by β‐CD showed a 1.42‐fold increase in the TiO2/UV–visible (λmax = 365 nm) system. The photodegradation of BPP depended on the concentration of β‐CD, the pH value, the gaseous medium and the initial concentration of BPP. The photodegradation efficiency of BPP with molecular recognition was higher than that without molecular recognition. After 100 min of irradiation the mineralisation efficiency of BPP after molecular recognition by β‐CD reached 94.8%, whereas the mineralisation efficiency of BPP before molecular recognition by β‐CD was only 40.6%. CONCLUSION: The photocatalytic degradation of BPP after molecular recognition by β‐CD can be enhanced in the TiO2/UV‐visible (λmax = 365 nm) system. This enhancement is dependent on the enhancement of the adsorption of BPP, the moderate inclusion depth of BPP in the β‐CD cavity and the increase in the frontier electron density of BPP after molecular recognition. Copyright © 2008 Society of Chemical Industry 相似文献
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159.
绿色理念的内涵拓展与绿色图书馆建设 总被引:1,自引:0,他引:1
绿色图书馆是图书馆学的一个新的研究方向和发展趋势.文章首先深刻挖掘绿色内涵的本质,阐述正确理解绿色图书馆的含义,接着探讨了绿色图书馆建设的要素取向,从而明确了现阶段发展绿色图书馆的必要性. 相似文献
160.
Guiying Li Ze He Taicheng An Xiangying Zeng Guoying Sheng Jiamo Fu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(7):1019-1026
BACKGROUND: To investigate the microbial degradation performance of organic pollutants in the atmosphere using a biotrickling filter, two microorganism strains, Bacillus cereus S1 and Bacillus cereus S2, were selected, identified and inoculated into a twin biotrickling filter for comparison. RESULTS: Both strains showed good performance towards the degradation of model organic pollutants when gas flow rates ranged from 100 to 600 L h−1. For S1, the total maximum removal efficiency (RE) of toluene was maintained nearly 100% not only at gas flow rates of 100 L h−1 corresponding to empty bed residence time (EBRT) 199.44 s, but also at gas flow rates of 200 L h−1 (EBRT = 99.72 s) and 300 L h−1 (EBRT = 66.48 s). However, S2 had a much lower degradation capability; near 100% removal efficiency was obtained only at the gas flow rate of 100 L h−1 although both bacteria belong to the same Bacillus cereus. With further increase in gas flow rate, the total REs for both S1 and S2 decreased slightly at first and then dropped sharply to 46% and 35%, respectively, at an EBRT of 33.24 s, corresponding to a gas flow rate of 600 L h−1. Starvation for between 2 and 10 days resulted in the re‐acclimation times of both strains ranging between 1.0 and 15.5 h. CONCLUSION: Strain S1 would be a better choice for inoculation into a biotrickling filter than strain S2, because of its much higher toluene removal capacity and rapid recovery to full performance. Copyright © 2008 Society of Chemical Industry 相似文献