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71.
This article examines the differential formation of online news startups in Toulouse, France, and Seattle, United States. While Seattle is home to many startups, in Toulouse there have been just 4—and only 1 continues publishing. Drawing on Bourdieu's field theory, we argue that amount and types of capital held by journalists in the 2 cities varied as a result of differences in journalism's position in the field of power. These differences shaped the extent of startup formation in each city and structured journalists' capacities to convert their capital into the resources needed to form startups (e.g., funding, credentials, partnerships). These findings are positioned in relation to literatures on journalism innovation and comparative media. 相似文献
72.
Koichi Fujiwara Manabu Kano Shinji Hasebe 《Chemometrics and Intelligent Laboratory Systems》2010,101(2):130-274
The individuality of production devices should be taken into account when soft-sensors are designed for parallelized devices. Since it is expressed as differences of the correlation among measured variables, it is useful to cluster samples on the basis of the correlation among variables for adopting a multi-model approach. In addition, changes in process characteristics can be coped with in the same way. In the present work, a new clustering method, referred to as NC-spectral clustering, is proposed by integrating the nearest correlation (NC) method and spectral clustering. Spectral clustering is a graph partitioning method that can be used for sample classification when an affinity matrix of a weighted graph is given. The NC method can detect samples that are similar to the query from the viewpoint of the correlation without a teacher signal. In the proposed method, the NC method is used for constructing the weighted graph that expresses the correlation-based similarities between samples and the constructed graph is partitioned by using spectral clustering. In addition, a new soft-sensor design method is proposed on the basis of the proposed NC-spectral clustering. The usefulness of the proposed methods is demonstrated through a numerical example and a case study of parallelized batch processes. The performance of the proposed correlation-based method is better than that of the conventional distance-based methods. 相似文献
73.
The present study is concerned with the human factors that contribute to violations in aviation maintenance. Much of our previous research in this area has been based on safety climate surveys and the analysis of relations among core dimensions of climate. In this study, we tap into mainstream psychological theory to help clarify the mechanisms underlying the links between climate and behavior. Specifically, we demonstrate the usefulness of Ajzen's (1991, 2001) Theory of Planned Behavior (TPB) to understanding violation behaviors in aircraft maintenance. A questionnaire was administered to 307 aircraft maintenance workers. Constructs measured by the survey included perceptions of management attitudes to safety, own attitudes to violations, intention to violate, group norms, workplace pressures, and violations. A model based on the TPB illustrated hypothetical connections among these variables. Path analyses using AMOS suggested some theoretically justifiable modifications to the model. Fit statistics of the revised model were excellent with intentions, group norms, and personal attitudes combining to explain 50% of the variance in self-reported violations. The model highlighted the importance of management attitudes and group norms as direct and indirect predictors of violation behavior. We conclude that the TPB is a useful tool for understanding the psychological background to the procedural violations so often associated with incidents and accidents. 相似文献
74.
《Advanced Powder Technology》2023,34(5):104005
One of the problems for the efficient operation of large industrial silos is that it is difficult to check the volume of the materials that remain inside the silo at any given time. This problem is more pronounced when materials from two or more sources are stored in a multiple-outlet silo, so that the profile of the mixed loading surface, i.e., the interface between materials from different sources, is not visible. To date, no research addressing this problem has been conducted. Therefore, this study proposes a model to predict the profiles of the top and mixed loading surfaces using the simple kinematic theory and considering the effect of the angle of repose on the shape of the top surface. The accuracy of the proposed prediction model was verified by comparing actual profiles of the top and mixed loading surfaces with those predicted by the model when materials were discharged from a multiple-outlet hopper with discharge sequences varying from the left, central, and right outlets. The results showed that the proposed model adequately predicted the profiles with relatively negligible errors. 相似文献
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77.
为解决卷烟企业成品自动化物流系统中双工位穿梭车搬运能力不足等问题,利用约束理论(Theory of Constraints,TOC)从检测器件设置、技术参数、物流工艺、自动控制、计算机调度等环节进行了综合优化改进:①通过现场试验测试优化穿梭车及其接口设备的技术参数;②把火警物流作业工艺流程改为消防报警联动;③穿梭车的启停、加减速由伺服控制器控制改为PLC控制;④穿梭车作业调度由先到先搬运策略改为数学模型优化调度.应用效果表明,改进后双工位穿梭车系统实际生产测试搬运能力由86.0盘/小时提高到133.7盘/小时,比生产额定需求能力118.6盘/小时高出15.1盘/小时.系统运行稳定可靠,有效解决了双工位穿梭车系统能力的瓶颈问题,提高了系统的有效作业率. 相似文献
78.
针对空压机控制系统中的节能减排、均衡调度和管网压力波动等问题,提出了空压机联动控制的多目标优化调度模型,并以改进惯性权重的粒子群算法进行求解。以灰色系统理论中的灰色关联度作为改进粒子群算法的适应度函数,对影响空压机联动系统的机组功耗、生产均衡调度和管网压力波动等多目标进行了优化求解。引入的非线性动态调整惯性权重策略改进了算法的全局收敛能力,有效地提高了粒子搜索过程中的智能性。通过某饮料罐装车间的技术改造,证明了本算法的有效性。 相似文献
79.
草珊瑚多糖对经脂多糖刺激的RAW264.7巨噬细胞的免疫调节作用研究 总被引:4,自引:0,他引:4
为研究草珊瑚多糖对RAW264.7巨噬细胞的免疫调节作用,建立LPS刺激的RAW264.7细胞模型,通过MTT法测定,观察草珊瑚多糖对RAW264.7细胞增殖影响并评价细胞毒性。同时,对草珊瑚多糖抑制模型细胞炎症因子一氧化氮(NO)表达及吞噬活性进行研究。结果表明,草珊瑚多糖可显著抑制RAW264.7细胞增殖水平,其细胞毒性分级为1级或以下。同时,草珊瑚多糖可显著抑制模型细胞NO表达及巨噬细胞吞噬活性。此研究将为深入研究草珊瑚抗炎活性作用机制及草珊瑚资源开发提供理论依据。 相似文献
80.
亲水性物质降低低糖果脯水分活性的研究 总被引:6,自引:0,他引:6
低糖果脯的保存期欲达12个月以上需使其水分活性(AW)降至0.65以下。通过研究不同浓度的柠檬酸、丙二醇等亲水性物质对低糖果脯AW的影响,复合亲水性物质降低低糖果脯AW的能力,以及同一亲水性物质对杏脯、山楂脯等低糖果脯AW的影响,最后明确亲水性物质与低糖果脯AW的关系。 相似文献