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91.
加快创新开发,开拓聚氯乙烯压力管道系统的新局面 总被引:5,自引:0,他引:5
近年来聚氯乙烯管道取得了重大进步。PVC-M管材(改性聚氯乙烯管材)、PVC-O管材(取向聚氯乙烯管材)兼有非凡的强度和韧度,和传统的硬聚氯乙烯管材比可以采用较高的设计应力,显著地节约材料。 相似文献
92.
The influences of nucleating agent content on crystallization peak temperature, crystallization curve shape, crystallization onset temperature, and crystallinity of a copolypropylene were studied in detail by differential scanning calorimetry. The results showed that crystallization onset temperature and crystallization peak temperature increased 17°C–22°C and 15°C–19°C, respectively, with increasing nucleating agent content. The behavior of the nucleating agent showed excellent efficiency. But the shape of the crystallization curve broadened with increasing nucleating agent content, and the crystallinity came to an extremum when the nucleating agent content was 0.2%. These results generally differed from those for crystallization of i‐PP by a nucleating agent. Modification of copolypropylene was studied by use of a nucleating agent, and the characteristics of the effects of the nucleating agent on copolypropylene were mastered. The results showed that the hardness of a copolypropylene improved observably. So the abrasion resistance of biaxially oriented polypropylene (BOPP) film for cigarette packaging was improved by adopting the modified copolypropylene as the skin‐layer heat‐seal material of BOPP film. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101:3915–3919, 2006 相似文献
93.
通量平衡分析是代谢工程研究中能够定量预测细胞内通量分布情况的有效工具,然而其预测准确性的前提是需要设计合理的代谢目标函数。研究了克雷伯氏杆菌歧化甘油生产1,3-丙二醇的代谢目标函数计算问题。该问题的数学形式是一个双层规划模型,首先应用线性规划的对偶理论将其转化为等价的单层非线性优化问题,然后采用非线性优化算法对其进行求解。与已有的研究结果相比,所提方法获得了克雷伯氏杆菌歧化甘油代谢的全局最优通量分布情况。 相似文献
94.
Raman spectra of virgin and damaged graphite edge planes 总被引:1,自引:0,他引:1
First-order Raman spectra of virgin and ion irradiated highly oriented pyrolytic graphite were performed along the basal and edge planes. Ion irradiation was performed in the low fluence regime (≈ 1012–1013 ions cm−2) using a 400 keV Ar+ beam in order to a introduce controlled amount of defects in the structure. Virgin edge Raman spectra reveal the presence of a 1351 cm−1 structure (D*) shifted 10 cm−1 away from the disorder induced D-line found upon irradiating or grinding the graphite surface.The 1351 cm−1 D* structure is then considered as the feature coming from the rupture of the D6h4 space group symmetry. A comparison between D* and the classical 1360 cm−1 D-line is discussed in terms of induced disorder. 相似文献
95.
Cloud Computing and Service Oriented Architectures have seen a dramatic increase of the amount of applications, services, management platforms, data, etc. gaining momentum for the necessity of new complex methods and techniques to deal with the vast heterogeneity of data sources or services. In this sense Quality of Service (QoS) seeks for providing an intelligent environment of self-management components based on domain knowledge in which cloud components can be optimized easing the transition to an advanced governance environment. On the other hand, semantics and ontologies have emerged to afford a common and standard data model that eases the interoperability, integration and monitoring of knowledge-based systems. Taking into account the necessity of an interoperable and intelligent system to manage QoS in cloud-based systems and the emerging application of semantics in different domains, this paper reviews the main approaches for semantic-based QoS management as well as the principal methods, techniques and standards for processing and exploiting diverse data providing advanced real-time monitoring services. A semantic-based framework for QoS management is also outlined taking advantage of semantic technologies and distributed datastream processing techniques. Finally a discussion of existing efforts and challenges is also provided to suggest future directions. 相似文献
96.
Yaokun Xiao Baicheng Weng Gang Yu Jinyin Wang Bonian Hu Zongzhang Chen 《Journal of Applied Electrochemistry》2006,36(7):807-812
This paper reports findings of an investigation of Pd–Ag alloy nanowires on the step edges of highly oriented pyrolytic graphite (HOPG) by electrochemical deposition at room temperature. Scanning electron microscopy (SEM) images reveal that these alloy nanowires (109–430 nm) are uniform in diameter, and have lengths up to 100–500 μm. The electrodeposition process involves the initial formation of nanowires induced at the step edges of the oxidized HOPG substrate at a very negative potential and subsequent growth at a constant low current density to coalesce the discontinuous nanowires. Alloy nanowires with a 20–25% silver content can be obtained when the ratio of Pd and Ag in the solution is carefully controlled. The SEM images demonstrate that the alloy nanowire arrays are continuous, parallel, ordered, well-aligned and have a narrow distribution of diameters. The Pd–Ag alloy nanowire arrays are promising materials for fabricating hydrogen nanosensors. 相似文献
97.
98.
Tapio Saarelainen 《通讯和计算机》2014,(2):124-132
The pace of war is increasing since militaries are adopting the ideas of NCW (network centric warfare). Therefore, the process of war has to be modeled into the BP (business process) in order to benefit from available resources in real-time. There is an increasing need to automate command and control tools utilized in military operations because of the versatility and increase d tempo of operations. Operations can be commanded and orchestrated with the assistance of SOA (service oriented architecture). SOA is currently seen as a technology that can satisfy these needs of NCO (network centric operations). The BPs are chains of logic that request SOA services. This paper argues that in the case of a military setting, in order to achieve maximum impact with minimal effort (cf. downsizing), military operations need to be modeled as BPs (e.g., a dismounted company attack). This asks for using a RM (resource manager), a scheduler and a BSS (battle secure scheduler) in allocating the requested services (e.g., processing a fire support order). In the future, a single FFW (future force warrior), an essential performer in military operations, can benefit from the BPs approach via enhanced performance, improved SA (situational awareness) and with decreased instances of fratricide. This introduced model examines war as a business process with the assistance of SOA and discusses how a business process--like orchestration of systems and services can improve the overall performance in given military settings. 相似文献
99.
100.
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