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991.
煤部分气化燃烧集成系统最优化模型及其求解 总被引:1,自引:1,他引:1
运用已有的基础动力学数据,将流化床气化过程用全混流模型描述,同时认为部分气化煤焦的燃烧速率相当快,其产生的电能只与燃烧的炭量成线性关系,不受其他因素的影响,在此简化条件的基础上建立了一个部分气化、燃烧集成优化的经济评价模型。通过对模型的模拟计算发现:煤部分气化、燃烧集成优化是可行的,采用这一集成技术在提高煤炭利用率的同时,也可提高经济效益;1000℃时,三种煤的最优气化率在60%~80%之间,活性好的神木煤其最优部分气化率最高;提高气化温度,可以提高煤焦最优气化率,从而可提高总体经济效益。 相似文献
992.
对硝基苯酚臭氧化反应动力学研究 总被引:6,自引:0,他引:6
在T=298K,pH=2.1~6,采用停流光谱仪研究了对硝基苯酚与臭氧在水溶液中的臭氧化反应动力学。实验结果表明,对硝基苯酚臭氧化总的反应是2级,对臭氧浓度和对硝基苯酚浓度分别为1级。臭氧化反应速率常数随溶液pH值的增大而增大;T=298K时,当pH值从2.1变化到6,总的反应速率常数从5.88×104L(mol·s)-1增大到1.56×106L(mol·s)-1。为了验证其适用性,对臭氧在搅拌釜中在对硝基苯酚溶液中的吸收过程进行了模拟。采用MATLAB软件求解臭氧在搅拌釜中在对硝基苯酚溶液中吸收过程的质量平衡方程,模拟得到了吸收过程中臭氧和对硝基苯酚浓度的变化,并与实验值进行了比较。结果表明,在85%的对硝基苯酚降解之前,模拟值和实验值能很好地一致。在反应末期,模拟值和实验值出现了一定的偏差。 相似文献
993.
研究了不同外加剂对陶瓷釉面表面性质的影响。研究表明 ,外加剂的加入可改变陶瓷釉面的表面张力 ,即影响液体对陶瓷釉面的润湿性能。在所选择的外加剂中 ,降低陶瓷釉面表面张力最强的为PbO ,其合适的加入量为 1.5 %。 相似文献
994.
The anionic polymerization of lauryllactam was initiated at 270°C using sodium hydride as an initiator and N,N′‐ethylene‐bisstearamide (EBS) as an activator (NaH:EBS molar ratio of 2). Polymerization occurred in less than 2 min and was successfully performed in an internal mixer and a twin‐screw extruder with corotating intermeshing screws (Werner & Pfleiderer ZSK 25). The content of residual monomer, as determined by thermogravimetric analysis, was lower than 0.5 wt %. Molecular weight, as measured by size exclusion chromatography, was governed by the lauryllactam:NaH molar ratio calculated on a Mn of 25 kg/mol at a constant NaH:EBS molar ratio of 2. Blends were prepared in situ by polymerization of lauryllactam solutions of various polymers. When poly(ethylene‐co‐butylacrylate) (Lotryl®; Atofina) was dissolved in lauryllactam, rubber‐toughened polyamide 12 blends were obtained. Mechanical properties of the injection‐molded polymers were examined by stress–strain as well as notched Charpy impact tests at different temperatures. Blend morphologies were imaged by scanning electron microscopy (SEM). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 344–351, 2003 相似文献
995.
996.
Coordination between strategic forest management and tactical logistic and production planning in the forestry supply chain 总被引:1,自引:0,他引:1
Jiehong Kong Mikael Rönnqvist 《International Transactions in Operational Research》2014,21(5):703-735
In this paper, we study the coordination mechanism in the forestry supply chain between strategic forest management and tactical production planning. We first formulate an integrated model to establish a theoretical benchmark for performance of the entire supply chain. It is a mixed integer programming model that involves harvesting, bucking, transportation, production, and sales decisions for both tactical and strategic planning levels. We then present two sequential approaches S‐A and S‐B where the coordination is done through internal pricing. S‐A is the approach currently used in practice where harvesting in the forest is the main driver of the supply chain activities and internal pricing is introduced to control bucking decision in a separate stage. In contrast, S‐B takes downstream demand information into consideration and internal pricing directly influences harvesting decision in the first stage. In order to find the appropriate setting of internal pricing that leads to the system optimum, we suggest two heuristics H‐I and H‐II. The internal pricing in H‐I is based on dual values and in H‐II, it is derived from a Lagrangian decomposition. A real‐life case study in the Chilean forestry industry is used to compare the results of different approaches. It is shown that the new sequential approach S‐B generates as good feasible solution as that obtained from the integrated approach but in much less time. Both heuristics H‐I and H‐II bring about near‐optimal feasible solutions. H‐II also provides optimistic bound of the optimal objective function value, which can be used as a measure of the solution quality. 相似文献
997.
针对高维数据导致的维数灾难问题,提出了一种基于面向分类准则的维数约简方法。所提准则使每个训练样本在特征空间中与同类样本尽可能接近,而与异类样本尽可能疏远。首先对每个训练样本定义同类样本加权平均距离和异类样本加权平均距离。然后基于上述两个概念分别定义总体同类距离和总体异类距离。以最小化总体同类距离和最大化总体异类距离为目的提出了面向分类的准则(Classification Oriented Criterion,COC)。最后,基于面向分类的准则推导出了一种新的维数约简方法。在公共人脸数据库ORL和Yale上的实验表明所提方法性能优于有代表性的维数约简方法。 相似文献
998.
999.
T. Lesage C. Verrier P. Bazin J. Saussey S. Malo C. Hedouin G. Blanchard M. Daturi 《Topics in Catalysis》2004,(1):31-36
In situ FT-IR spectroscopy coupled with mass spectrometry have been used to study the mechanism of nitrates formation and reduction over a common Pt–Rh/Ba/Al2O3 NO
x
storage catalyst, compared with a different alumina-based compound.The experimental device used consists of a transmission reactor cell (having a very small dead volume) dedicated to the evolution of surface species, and of a mass spectrometer combined with a FT-IR micro-cell for gas analysis, allowing time resolved analysis in stationary and transient conditions.At the first time the nitration properties of the catalysts under a lean flow have been studied in the appropriate temperature window (473–673 K). The dynamics of nitrates formation has been pointed out, as well as the different coordination sites on the compounds surface. Then the catalysts have been alternatively exposed to rich and lean flows very close to the real exhaust composition. This has allowed the identification of reduction pathway, active sites, intermediate species and by-products for NO
X
-trap reaction. In particular, we have differentiated the role of the support and of the noble metal in the mechanism, as well as of isocyanate adspecies and ammonia among the detected species. The very high NO
X
storage properties and the selectivity (near 100%) in nitrogen of the newly designed catalyst have been pointed out. 相似文献
1000.