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51.
氯盐腐蚀条件下钢筋混凝土结构抗力衰减模型研究 总被引:1,自引:0,他引:1
采用改进的Fick第二扩散定律来描述混凝土内氯离子的扩散过程,从而可以预测混凝土内钢筋开始锈蚀的时间;建立了均匀腐蚀、点腐蚀以及两者同时存在条件下的钢筋腐蚀速度模型,为结构抗力衷减规律的研究奠定了基础。算例表明建立的模型是合理的。 相似文献
52.
本文提出了一种水闸老化的模糊集合论评估方法。该方法是:首先把水闸分解成部件,然后就每个部件的安全性、适用性和耐久性及其所属的若干单因素评估指标,计算出部件老化的综合隶属度,再用系统综合的方法评出整个水闸的老化级别。本方法的绝大多数数据都来源于实际检测资料,并以现行标准和规范作为准绳进行评估,因而得出的评估结构比较准确。 相似文献
53.
开发了新的高精度钢与钢管混凝土(concrete-filled steel tube,CFST)的损伤与性能退化模型,研究了钢管混凝土柱在超高轴压下的抗震性能及其退化规律,基于该退化本构模型开发了纤维有限元仿真程序.基于长周期地震波峰值速度,分析了高层钢管混凝土框架在长周期地震作用下的倒塌行为.通过建立了高层CFST框... 相似文献
54.
《Structure and Infrastructure Engineering》2013,9(2):99-110
Concrete structures in the atmosphere may suffer from the problem of steel corrosion induced by the carbonation process. Most of previous research on concrete carbonation problems has been performed on the macro-scale. These studies did not consider the influence of the aggregates, which should be involved on meso-scale. In order to extend the present studies on the problems of concrete carbonation from macro-scale to meso-scale, an improved method to simulate the random aggregate structure (RAS) in concrete has been proposed. This method can be divided into two steps: the process of RAS in a three-dimensional model, and the process of numerical analysis in a cross-section. In this method, the effect of the randomness on the results of RAS is analysed. Based on the mass conservation law and kinetic model of chemical reactions, a simplified numerical model of concrete carbonation is developed. The effect of the key parameters in this model such as effective diffusion coefficient of CO2 and carbonation reaction constant is discussed. The comparison of the simulations of concrete carbonation process on macro-scale and meso-scale is discussed as well. Finally, an application of the method to determine the proper composition of concrete in the practical engineering is presented. 相似文献
55.
Swift Joshua K.; Callahan Jennifer L.; Heath Christopher J.; Herbert Gregory L.; Levine Jason C. 《Canadian Metallurgical Quarterly》2010,47(2):235
While previous research on deterioration has focused on identifying individuals at risk for negative outcomes, little is known about the nature or pattern by which deterioration occurs. The problem of deterioration is especially salient in training clinics; a setting in which higher deterioration rates have been reported. Two studies were designed to test the applicability of the phase model to deterioration in a training clinic and to replicate the model with a training clinic referral-base sample. In Study 1, the course of therapy was monitored for 135 clients. For the 38 clients who deteriorated during therapy, a model where increased symptoms (demediation) reliably preceded both decreased functioning (dehabilitation) and decreased well-being (demoralization) was found. In Study 2, the same three phases were prospectively monitored for 914 undergraduate students on a weekly basis throughout a single semester. For the 158 individuals who deteriorated during this time, a model where demediation reliably preceded dehabilitation, which preceded demoralization was found. These results have clinical implications for the use of tailored intervention strategies focusing on the deterioration phases. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
56.
近年来国内钢铁市场的迅猛发展,导致钢铁工业上游市场的原燃材料价格不断暴涨。广钢为缓解上游成本压力,在工艺上采取了一系列措施以应对原燃料劣化问题,确保高炉顺行。 相似文献
57.
《Structure and Infrastructure Engineering》2013,9(11):1080-1092
Corrosion of embedded carbon steel is a leading factor in deterioration of ageing conventional reinforced concrete structures. Methods to accurately predict remaining capacity of corrosion damaged elements, especially shear capacity, are lacking. In this paper, ACI-AASHTO approach, strut and tie method, modified compression field theory, and Response 2000? were used to predict the shear strength of corrosion damaged and undamaged test beams. The methods were modified to account for the corrosion induced damage to both the concrete section and stirrups. Each of the methods considered, with the proposed modifications, reasonably estimated the remaining shear capacity of large-size laboratory specimens subjected to accelerated corrosion of embedded stirrups. 相似文献
58.
59.
Pellicle formation,microbial succession and lactic acid utilisation during the aerobic deteriorating process of Sichuan pickle
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Yu Rao Yang Qian Xiao She Jiantao Yang Penghui He Yunlu Jiang Meng Wang Wenliang Xiang 《International Journal of Food Science & Technology》2018,53(3):767-775
The pellicles formation, microbial changes and lactic acid utilisation during the aerobic deterioration of Sichuan pickle were discussed in this study. By plate counting, chemical detection and HPLC analysis, the aerobic deterioration of Sichuan pickle was featured by microbial growth, pellicle formation, lactic acid decrease and pH elevation. Bacteria dominated in pellicles and the pellicles present morphological change from smooth to wrinkly along with the aerobic deteriorating process. Nine species of bacteria were identified and responsible for the pellicle formation. Combined with Lactobacillus plantarum, eight pellicle‐forming bacteria were the dominant lactic acid consuming organisms in deteriorating Sichuan pickle. Especially under the harsh acid condition of the early deteriorating period, Lb. plantarum, pellicle‐forming bacteria Bacillus amyloliquefaciens, B. subtilis and Citrobacter freundii participated in the pellicles, utilised lactic acid and increased the brine pH effectively. Sequence analysis of 16S rDNA libraries suggested that the resulting pH of 4.8–5.0 initiated the growth of more undesirable organisms, and the pellicle bacterial diversity changed greatly compared with that in the early deteriorating period. The study indicated the important role of pellicles in the initiation of Sichuan pickle's aerobic deterioration and enhanced our ability to understand and potentially control the aerobic deterioration. 相似文献
60.
本文扼要论述了食用油脂的劣化现象、油脂自动氧化的机理、影响油脂劣化的因素、油脂稳定性的试验方法、油脂氧化程度的测定方法、油脂劣化的防止措施及开展迷迭香天然食用抗氧化剂研究的必要性。 相似文献