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排序方式: 共有4862条查询结果,搜索用时 15 毫秒
1.
Xiehuan Li Dan Ye 《International Journal of Adaptive Control and Signal Processing》2022,36(1):104-121
In this article, the memory-based dynamic event-triggered controller design issue is investigated for networked interval type-2 (IT2) fuzzy systems under non-periodic denial-of-service (DoS) attacks. For saving limited network bandwidth, a novel memory-based dynamic event-triggered mechanism (DETM) is proposed to schedule data communication. Unlike existing event-triggered generators, the developed memory-based DETM can utilize a series of newly released signals and further save network resources by introducing interval dynamic variables. Moreover, to improve design flexibility, an IT2 fuzzy controller with freely selectable fuzzy rule number and premise membership functions (MFs) is synthesized. Then, a new switched time-delay system with imperfectly matched MFs is established under the consideration of memory-based DETM and DoS attacks simultaneously. Besides, based on the property of MFs, the boundary information of membership grades and slack matrices are introduced in the stability analysis. Furthermore, by using a piecewise Lyapunov–Krasovskii method, membership-functions-dependent criteria are deduced to ensure the asymptotic stability of built fuzzy switched systems. Finally, the effectiveness of proposed control strategies is demonstrated by simulation examples. 相似文献
2.
To design robust interval observers for uncertain continuous‐time linear systems, a new set‐integration approach is proposed to compute trajectory tubes for the estimation error. Because this approach, the order‐preserving condition on the dynamics of the estimation error is no longer required. Therefore, synthesis methods can be used to compute observer gains that reduce the impact of the system uncertainties on the accuracy of the estimated state enclosures. The performance of the proposed approach is showcased through illustrative numerical examples. 相似文献
3.
准噶尔盆地南缘中、下组合构造普遍位于中浅层砾岩层之下,砾岩层具有横向展布范围广且不规则、纵横向速度变化大等特点,严重制约中、下组合目标的精细落实。因此,搞清砾岩层结构及分布特征,对下伏构造形态和高点位置的准确落实尤为重要。结合微测井、钻井、测井资料以及地震剖面对准噶尔盆地南缘四棵树地区中浅层砾岩层结构特征进行分析,对低速和高速砾岩层的顶底界面进行识别刻画,并分区、分段建立了砾岩层时深关系曲线,用于指导深度域下组合构造成图和叠前深度偏移中浅层速度模型的建立。实例应用证明,南缘四棵树地区中浅层砾岩层识别刻画对准确落实构造目标,提高地震剖面成像品质至关重要,同样也可以在准噶尔盆地南缘其他类似地区进行推广应用。 相似文献
4.
IntroductionThe main purpose of this cross-sectional study was to investigate whether visual discomfort acts as a mediating factor between perceived visual ergonomic working conditions and self-rated visual performance among office workers who carry out administrative tasks and computer-based work at the Swedish Tax Agency.MethodsA questionnaire was sent to 94 office workers addressing: 1) perceived visual quality of the visual display units; 2) prevalence of eye symptoms; and 3) self-rated visual performance. Eighty-six persons (54 women (63%), 31 men (36%), and 1 of unspecified sex) answered the questionnaire. Multiple regression analysis investigated the association between visual ergonomic working conditions and visual performance, both with and without visual discomfort as a mediator.ResultsThe group mean of the Indexed survey questions indicated a reasonably good quality of visual ergonomic working conditions, a relative absence of eye symptoms, and acceptable self-rated visual performance. Results from multiple regression analysis showed a significant association between perceived visual ergonomic working conditions and self-rated visual performance (r2 = 0.30, β = 0.327, p < 0.01). When visual discomfort was used as a mediator, the association between perceived visual ergonomic working conditions and self-rated visual performance remained the same (r2 = 0.32, β = 0.315, p < 0.01).DiscussionIt was remarkable to discover that self-rated visual performance was independent of visual discomfort. Possible explanations include exposure factors not included in the current study, such as dry air and sensory irritation in the eyes, psychosocial stress, time spent performing near work activities, or time exposed to visually deficient working conditions.Relevance to industryThe strong connection between satisfaction with visual ergonomic working conditions and productivity in this study has implications for workplace profitability and staff satisfaction. If productivity is enhanced by better visual ergonomic working conditions, then managers of workplaces may be able to improve work outcomes by optimizing the physical work environment. 相似文献
5.
同时考虑性能极限状态随机性及相关性,提出结构系统多维易损性评估方法。开展增量动力分析获取极限状态阈值样本,构造多维性能极限状态方程,创新地提出二维性能极限状态带确定结构失效域,借助区间估计确定某一置信水平下极限状态带上、下界,利用相关系数定量描述极限状态相关程度。开展非线性动力时程分析获取需求参数,建立结构多维概率地震需求模型,以桥梁系统为例计算多维易损性置信区间,开展易损性敏感性分析。结果表明性能极限状态带可较好解决极限状态随机性问题,多维易损性区间长度随极限状态带置信度的下降而变窄;随着极限状态相关系数的增加,极限状态相关性变弱,易损性评估结果偏小,产生非保守估计,不利于结构风险控制。 相似文献
6.
7.
M. Abdulkareem A. Ganiyu O. Nathaniel I. Mallum W. Dunu 《Materialwissenschaft und Werkstofftechnik》2021,52(10):1064-1072
Various damage detection methods have been proposed by several researchers in the past few decades. Amongst them, the efficiency of mode shapes in detecting damage has been demonstrated by many researchers when further processed. In most cases, the processing involves expansion or reduction of the mode shape data. However, vital information that are damage-prints are often lost during processing of the mode shape data. In addition, most of these processes involve long and complex computation, thus, leading to inaccurate damage identification. In this study, a simple and fast damage identification technique is proposed to identify damage in beam structures. Interval analysis is applied to the mode shapes of a beam structure in the damaged and undamaged states. The interval situations of each of the beam's segment via mode shape are derived to obtain the upper and lower bounds and the derived bounds are compared. To establish a relationship for identify the damaged point, a possibility of damage existence is defined for each segment of the beam structure. The mode shape increment is defined as the increase in the mode shape value. Furthermore, a damage measure index that provide enhance damage information is obtained as the product of the possibility of damage existence and mode shape increment. A numerical model of a simply supported steel beam is applied to demonstrate this method by imposing damage through thickness reduction of elements in segments. In addition, a parametric analysis is carried out to evaluate noise effect by considering varying damage severities and different noise levels. The results showed that this method is simple and provides considerable accurate results. 相似文献
8.
9.
In this paper, the problem of mining complex temporal patterns in the context of multivariate time series is considered. A new method called the Fast Temporal Pattern Mining with Extended Vertical Lists is introduced. The method is based on an extension of the level‐wise property, which requires a more complex pattern to start at positions within a record where all of the subpatterns of the pattern start. The approach is built around a novel data structure called the Extended Vertical List that tracks positions of the first state of the pattern inside records and links them to appropriate positions of a specific subpattern of the pattern called the prefix. Extensive computational results indicate that the new method performs significantly faster than the previous version of the algorithm for Temporal Pattern Mining; however, the increase in speed comes at the expense of increased memory usage. 相似文献
10.
为解决翻领松量计算精准性及翻折领通用结构设计方法的问题,提出了一种基于翻领松量结构模型的翻折领结构设计方法。通过构建翻领松量结构模型确定了翻领松量计算系数,对6种不同状态下的翻领间隙量变化进行数据统计分析,依据翻领间隙回归系数模型确定了翻领松量计算给定常数,运用SPSS统计软件对实验数据进行了相关性分析、回归分析、配对样本T检验,并推导出翻领松量计算公式。实验结果表明:使用该公式计算的翻领松量提高了翻折领结构造型的准确性,基于翻领松量结构模型的翻折领结构设计方法可以满足不同翻折领领型结构设计要求。 相似文献