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1.
Accurate and timely network traffic measurement is essential for network status monitoring, network fault analysis, network intrusion detection, and network security management. With the rapid development of the network, massive network traffic brings severe challenges to network traffic measurement. However, existing measurement methods suffer from many limitations for effectively recording and accurately analyzing big-volume traffic. Recently, sketches, a family of probabilistic data structures that employ hashing technology for summarizing traffic data, have been widely used to solve these problems. However, current literature still lacks a thorough review on sketch-based traffic measurement methods to offer a comprehensive insight on how to apply sketches for fulfilling various traffic measurement tasks. In this paper, we provide a detailed and comprehensive review on the applications of sketches in network traffic measurement. To this end, we classify the network traffic measurement tasks into four categories based on the target of traffic measurement, namely cardinality estimation, flow size estimation, change anomaly detection, and persistent spreader identification. First, we briefly introduce these four types of traffic measurement tasks and discuss the advantages of applying sketches. Then, we propose a series of requirements with regard to the applications of sketches in network traffic measurement. After that, we perform a fine-grained classification for each sketch-based measurement category according to the technologies applied on sketches. During the review, we evaluate the performance, advantages and disadvantages of current sketch-based traffic measurement methods based on the proposed requirements. Through the thorough review, we gain a number of valuable implications that can guide us to choose and design proper traffic measurement methods based on sketches. We also review a number of general sketches that are highly expected in modern network systems to simultaneously perform multiple traffic measurement tasks and discuss their performance based on the proposed requirements. Finally, through our serious review, we summarize a number of open issues and identify several promising research directions. 相似文献
2.
目前已有的代码坏味检测方法仅依赖于代码结构信息和启发式规则,对嵌入在不同层次代码中的语义信息关注不够,而且现有的代码坏味检测方法准确率还有进一步提升的空间.针对该问题,提出一种基于预训练模型和多层次信息的代码坏味检测方法 DeepSmell,首先采用静态分析工具提取程序中的代码坏味实例和多层次代码度量信息,并对代码坏味实例进行标记;然后通过抽象语法树解析并获取源代码中与代码坏味相关的层次信息,将其中的文本信息与度量信息相结合生成数据样本;最后使用BERT预训练模型将文本信息转化为词向量,应用GRU-LSTM模型获取层次信息之间潜在的语义关系,并结合CNN模型与注意力机制检测代码坏味.在实验中,选取JUnit、Xalan和SPECjbb2005等24个大型实际应用程序构建训练集和测试集,并对特征依恋、长方法、数据类和上帝类等4种代码坏味进行检测.实验结果表明, DeepSmell与目前已有的检测方法相比在平均查全率和F1值上分别提高了9.3%和10.44%,同时保持了较高的查准率, DeepSmell可以有效地实现代码坏味检测. 相似文献
3.
Erick B. F. Galante Nathalie Mai Melissa K. Ladyman Philip P. Gill Frederic Coulon 《Journal of Energetic Materials》2021,39(1):85-99
ABSTRACT Energetic materials are often disposed by open-burning or open-detonation as it is a cost-effective and efficient means of destroying explosive material, and often minimizes the need to transport hazardous explosives to treatment facilities. This practice is often scrutinized for the negative environmental impact of the odorous and unsightly toxic gaseous emissions as well as the resulting deposition residues, which often contain unburned energetic materials. With the increasing use of Insensitive High Explosive compositions in munitions, it is essential that the potential environmental impact of their disposal is assessed before their extensive use to prevent the kind of contamination incidents experienced with legacy explosives. Therefore, the aim of this work was to develop a controlled laboratory experiment to identify the gaseous emissions and the energetic material residues that are generated through the combustion of the IHE components 3-nitro-1,2,4-triazol-5-one (NTO), 2,4-dinitroanisole (DNAN), and 1,3,5-trinitroperhydro-1,3,5-triazine (RDX). A sealed vial containing small (mg) quantities of energetic material was heated until the energetic material combusted. Gas chromatography/mass spectrometry (GCMS) was used to calculate the oxygen consumption and to identify the gases that were generated. The solid residues were analyzed by high-performance liquid chromatography (HPLC) to quantify unburned energetic material. Results showed that DNAN was the most resistant to burning, thus leaving significant quantities of unreacted starting material in the vial. An interesting observation for the IHE formulation was that DNAN also inhibited the combustion of NTO and RDX. The gases emitted during the open burning of IHE components and mixtures included CO, CO2, and N2O as expected, but the proportions differed when the components and mixture were compared, reflecting the influence of DNAN on the burning behavior. From our data, we concluded that open-burning DNAN-based formulations is an environmentally unfavorable waste-management practice for the disposal of IHEs mainly due to generation of solid residues as well as unburnt DNAN. 相似文献
4.
2021年开始实施的《民法典》对我国矿业权制度进行了系统性治理。在权利性质方面,《民法典·物权编》确立了采矿权的用益物权属性,有助于《矿产资源法》的相关修订消除矿业权制度与物权因素的冲突。在矿业权流转方面,《民法典》绿色原则的确立,使符合生态资源保护成为矿业权流转合同的生效要件;而矿业权的得丧变更需符合物权变动的区分原则,从许可制转向登记制,突出了行政许可因素的剥离。《民法典·侵权责任编》则对采矿挖掘等行为造成的环境损害责任如何认定与分配损失,确立了"绿色原则"指导下的生态损害赔偿规则与集体诉讼制度。 相似文献
5.
代码重用攻击的实施过程较为繁杂,通常需要一些工具辅助人工来完成gadget序列的构建,但现有的自动化构建工具效率较低。在分析Ropper、angrop和BOPC等典型开源gadget工具语义分析内容的基础上,总结gadget语义分析应包含的要素,提出一种基于表达式树的gadget语义分析方法。通过表达式树变体描述寄存器和内存读写的表达式信息,提高gadget语义分析的效率。实现一个gadget搜索与语义分析工具SemExpr,针对现有gadget工具难以进行对比分析的问题,设计能对多种gadget工具进行效率和效能分析的实验系统gadgetAnalysis。基于该系统进行实验,结果表明,SemExpr工具能够权衡效率和效能,取得较好的语义分析效果。 相似文献
6.
7.
Against the backdrop of global climate change and in regards of urban sustainable development, enhancing climate resilience has become a critical strategy in adapting climate change for urban areas, where blue-green infrastructure is considered an important means. Although existing studies mention that blue-green infrastructure (BGI) can promote urban resilience by increasing its own diversity, flexibility, redundancy, modularization, and decentralization, questions like where to promote, by what specific means to promote and to what extent it could promote to are still lack of scientific exploration, leading insufficient support for applying resilience theory into planning and design practice. This research recognizes the role of BGI in building climate resilience in the key fields of functioning–urban floods, sea level rise, and high temperature and heat waves–and summarizes that the common functioning mechanisms include the biophysical properties of BGI, forming modular units with other infrastructures of similar functions, and the reliance on networked structures to help the system restore its physical functions and social connections as quickly as possible after disturbances and attacks. This paper also analyzes possible obstacles that hinder the promotion of BGI solutions–the lack of data support to BGI functioning mechanism, the lack of comprehensive assessment on ecological-social-economic benefits, and the difficulty in gaining confidence from decision-makers and the public. Finally, this paper proposes countermeasures from aspects of theoretical development, planning practice, and implementation and management, in order to offer insights for building urban climate resilience. 相似文献
8.
Jiacheng CHEN 《景观设计学(英文)》2021,9(2):120
The Black Dirt Region in the State of New York has been well-known for the unique taste of its onions, which is attributed to the organic matter that weighs over 80% in the soil. In recent years, however, the rigid economic pattern restrains the development of this area. In the meantime, local agricultural production is more and more vulnerable to flooding. When this region is labeled as “highly productive of crops,” the persistent factors that have been shaping the black-dirt landscape are omitted. The other name of the place, “the Drowned Lands,” may better capture its entangled relationship with water. In this article, hydrogeological dynamics and human desire are regarded as the factors that sustain landscape continuity and stability. Based on the research on historical sedimentation in the Drowned Lands, this article attempts to delineate a local scenario of covert landscape evolution since the Last Glacial Maximum. The proposal initiates a composite pathway of ecological functions and touristic values in the agricultural region. Within a series of “landscape prompts,” a lesser-known tale of local geology and prehistoric culture is told. Through design interventions, alternative possibilities of rural landscape are tested, embedded meaning of the agricultural land becomes tangible, and a more adaptive human–land relationship is restored. 相似文献
9.
Tao Chen Meiqing Fu Rui Liu Xuanhua Xu Shenbei Zhou Bingsheng Liu 《International Journal of Project Management》2019,37(3):485-500
Due to the increasing complexity and flexibility of business activities, project-based organizations have become common. In such organizations, project management competencies, which refer to a collection of knowledge, personal attitudes, skills, and relevant experience, are core assets that must be taken seriously. Formalized project management career paths have been widely implemented in the construction industry. However, most recent studies treat project management competencies as static constructs and fail to consider their dynamic changes as a career path advances. To fill this gap in the literature, this study conducted an empirical examination of project management competencies integrated with a career model for the construction industry. First, key project management competencies are identified through a literature review. Then, a project management career model for large Chinese construction companies is developed based on an empirical investigation of six large Chinese construction companies from various sectors. Moreover, a quantitative analysis is performed to explore how these competencies dynamically change as position levels rise in the career model. The research findings indicate that significant differences in project management competencies exist at different levels of the career model. However, the distribution remains steady at different project management position levels for conceptual and organizational competencies, human competencies, and technical competencies. 相似文献
10.
Detecting change areas among two or more remote sensing images is a key technique in remote sensing. It usually consists of generating and analyzing a difference image thus to produce a change map. Analyzing the difference image to obtain the change map is essentially a binary classification problem, and can be solved by optimization algorithms. This paper proposes an accelerated genetic algorithm based on search-space decomposition (SD-aGA) for change detection in remote sensing images. Firstly, the BM3D algorithm is used to preprocess the remote sensing image to enhance useful information and suppress noises. The difference image is then obtained using the logarithmic ratio method. Secondly, after saliency detection, fuzzy c-means algorithm is conducted on the salient region detected in the difference image to identify the changed, unchanged and undetermined pixels. Only those undetermined pixels are considered by the optimization algorithm, which reduces the search space significantly. Inspired by the idea of the divide-and-conquer strategy, the difference image is decomposed into sub-blocks with a method similar to down-sampling, where only those undetermined pixels are analyzed and optimized by SD-aGA in parallel. The category labels of the undetermined pixels in each sub-block are optimized according to an improved objective function with neighborhood information. Finally the decision results of the category labels of all the pixels in the sub-blocks are remapped to their original positions in the difference image and then merged globally. Decision fusion is conducted on each pixel based on the decision results in the local neighborhood to produce the final change map. The proposed method is tested on six diverse remote sensing image benchmark datasets and compared against six state-of-the-art methods. Segmentations on the synthetic image and natural image corrupted by different noise are also carried out for comparison. Results demonstrate the excellent performance of the proposed SD-aGA on handling noises and detecting the changed areas accurately. In particular, compared with the traditional genetic algorithm, SD-aGA can obtain a much higher degree of detection accuracy with much less computational time. 相似文献