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91.
92.
基于轨迹线性化控制(TLC)理论提出了一种全驱动平流层飞艇轨迹跟踪控制设计的新方法.该方法由期望姿态生成、运动学控制和动力学控制3部分组成.首先利用期望轨迹的Frenet标架构造期望的艇体坐标系,导出期望姿态的计算公式;然后将系统运动学部分按照移动和转动分解,动力学部分按纵向与横向分解,将整个系统划分为4个回路,并分别用TLC理论进行控制设计,避免了设计时对全系统求逆的困难;最后给出了控制方法的计算步骤和平流层飞艇跟踪典型轨迹的仿真结果,结果验证了所提出方法的可行性. 相似文献
93.
The paper describes results of a longitudinal study of developments in the area of software product and process quality improvement within a Hungarian software company, IQSOFT Ltd. This company has been active in this area since 1993, trying to build, introduce and maintain an efficiently working quality management system which, e.g., fulfils the ISO 9001 requirements, allows steady software process improvement and, at the same time, conforms to company's own needs. Over the last eight years five phases could be distinguished. Each phase is described shortly, following the same structure, namely: basic starting points, key problem areas, literature consulted, activities and design executed, reflections on what happened and why. The lessons resulting from the analysis of this case have been formulated in terms of guidelines. We feel that these are applicable to any low maturity software development organisation embarking on a product or process quality improvement endeavour. These guidelines are developed around a framework containing the basic issues of software production (project management, technical processes and products). The guidelines advocate a careful step-by-step development of definitions, quality characteristics, and metrics related to these objects while at the same time developing and introducing the associated process. 相似文献
94.
A longitudinal assessment of the introduction of new office technologies into a multinational bank was conducted using both task diaries and semi-structured interviews. Task diaries were administered prior to the introduction of microcomputers, several months after the introduction and several years later. Semi-structured interviews were completed after the second task diary. The assessment provides evidence of how offices adapt to changing electronic tookits. The asssessment provides ergonomists with a usable list of taks activities and the effects on task variability of the adoption of microcomputers into the work routine. It shows that when support staff are asked to use a new computer they must choose what other tasks to cut back on, which has consequences for the overall work process. Overtime increased 170% after the introduction of the computer. In a culture where professional staff have high expectations of support staff this has consequences for working relationships in terms of perceptions of the computer's utility. Support staff and professional staff differ in perceptions of control, time-saving and ability to make corrections. The assessment demonstrates the importance of multiple measurement instruments in tracking the effects of technological change on the work process. In conclusion, it is noted that the introduction of new technologies into the office must be considered in the broader office context to avoid the unintended consequences often reported in other case studies. 相似文献
95.
G. J. Gruber 《Journal of Nondestructive Evaluation》1980,1(4):263-276
Shape and size are the most important defect characteristics that need to be determined for the reliable prediction of the remaining service lifetime of a defective structure or part. The analytical and supporting experimental results presented in this paper concern a general, pattern recognition-based, ultrasonic defect identification and sizing method. The satellite-pulse technique (SPT) is based on the interpretation, in terms of defect types (shapes) and dimensions, of the separation in time of arrival between the readily detected specularly reflected pulse and its generally ignored tip-diffracted or tangentially scattered satellite contained in the received waveform. Calibration procedures were also developed that enable the ultrasonic examiner to read the time scale of the oscilloscope for equivalent crack depth or void diameter as appropriate. 相似文献
96.
The present studies concentrated on predicting the remaining fatigue life for single fatigue cracks in the Paris regime of macrocrack propagation. Acoustic surface waves were used to interrogate the crack during cyclic fatigue. The inversion of the obtained scattering data provided crack depth and crack length as a function of the number of cycles applied in tension-tension fatigue. Auxiliary experiments were conducted to study the acoustic response of the crack to tensile and compressive loads, thought to open and close the crack. The technique may allow for new insights into the physics of the crack closure effect. 相似文献
97.
《Behaviour & Information Technology》2012,31(2):185-204
Researchers and practitioners in the field of information and communication technologies (ICT) have for a while been embracing the concepts of user and consumer experience as well as emotions in design, encouraging the industry to emphasise hedonic and symbolic qualities of products and services, over and beyond their utilitarian characteristics. However, the idea that mobile phone users, for instance, seek increasingly experience-rich, personalised products can not be taken for granted. Therefore, it is valuable to investigate the degree to which users really share designers' increasingly socio-emotional stances. The presented longitudinal study investigated users' mobile phone-related product meaning, particularly its development from 2004 to 2008. Product meaning was conceptualised in terms of an affective-cognizant choice mode dimension complemented by items capturing utilitarian, hedonic, and symbolic facets of the construct. The findings provide grounds for raising an important discussion about a possible pragmatic shift in product meaning, away from emotional and holistic, towards piecemeal and rational valuation. This would obviously challenge current design maxims. Linking these results to users' personality and mobile phone ownership history, subgroups with notably dissimilar product meaning development could be distinguished mainly with regard to levels of neuroticism, extraversion and brand loyalty – however, not gender. 相似文献
98.
《Behaviour & Information Technology》2012,31(12):1161-1171
The principal objective of this study was to gain insight into attitude changes occurring during IT acceptance from the perspective of elaboration likelihood model (ELM). In particular, the primary target of this study was the process of IT acceptance through an education program. Although the Internet and computers are now quite ubiquitous, and thus many people can come to an acceptance of IT organically – including acceptance of such products as new released online services or software, some software – most notably programming languages and spreadsheets – may require education programs, and the efficacy of that education may determine the rate of acceptance. Thus, education programs for such IT may be regarded as not only teaching and training how to use the product from a technical standpoint, but also as a process by which program participants are persuaded to have a positive attitude towards accepting the new IT. This study adopted an ELM based longitudinal approach to capture the changes in the roles of persuasion routes and attitude during IT acceptance – in this case, the education program. To validate empirically the suggested model, junior students majoring in business administration, all of whom were taking an Excel class, were surveyed twice – just after mid-term and just after their final exam. These data were analysed via partial least-square method to deduce some possible implications. Our results supported all the hypotheses put forward. 相似文献
99.
100.
本文主要介绍努尔加水库台阶式溢洪道的试验研究成果。通过模型试验,对单宽流量在24.17—118m3/s.m的台阶式溢洪道的台阶坡度,高度和水力特性认识更加深入。试验表明坡度较陡,单宽流量较小的情况下消能效果最好。研究工作对大单宽流量台阶溢洪道的推广应用具有较高的参考价值。 相似文献