全文获取类型
收费全文 | 92025篇 |
免费 | 19914篇 |
国内免费 | 2652篇 |
专业分类
电工技术 | 4175篇 |
技术理论 | 4篇 |
综合类 | 3918篇 |
化学工业 | 25400篇 |
金属工艺 | 3581篇 |
机械仪表 | 4451篇 |
建筑科学 | 6117篇 |
矿业工程 | 1819篇 |
能源动力 | 2519篇 |
轻工业 | 11207篇 |
水利工程 | 1386篇 |
石油天然气 | 3532篇 |
武器工业 | 475篇 |
无线电 | 13061篇 |
一般工业技术 | 17533篇 |
冶金工业 | 2997篇 |
原子能技术 | 673篇 |
自动化技术 | 11743篇 |
出版年
2024年 | 328篇 |
2023年 | 1195篇 |
2022年 | 2186篇 |
2021年 | 3148篇 |
2020年 | 3710篇 |
2019年 | 4909篇 |
2018年 | 4947篇 |
2017年 | 5447篇 |
2016年 | 5663篇 |
2015年 | 6572篇 |
2014年 | 6908篇 |
2013年 | 8441篇 |
2012年 | 6376篇 |
2011年 | 6165篇 |
2010年 | 5895篇 |
2009年 | 5565篇 |
2008年 | 5156篇 |
2007年 | 4746篇 |
2006年 | 4437篇 |
2005年 | 3748篇 |
2004年 | 2933篇 |
2003年 | 2668篇 |
2002年 | 2700篇 |
2001年 | 2317篇 |
2000年 | 2128篇 |
1999年 | 1614篇 |
1998年 | 900篇 |
1997年 | 749篇 |
1996年 | 654篇 |
1995年 | 549篇 |
1994年 | 467篇 |
1993年 | 295篇 |
1992年 | 246篇 |
1991年 | 178篇 |
1990年 | 153篇 |
1989年 | 111篇 |
1988年 | 76篇 |
1987年 | 76篇 |
1986年 | 63篇 |
1985年 | 31篇 |
1984年 | 22篇 |
1983年 | 22篇 |
1982年 | 15篇 |
1981年 | 24篇 |
1980年 | 19篇 |
1979年 | 10篇 |
1978年 | 5篇 |
1975年 | 3篇 |
1959年 | 4篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
首先从材料力学角度分析了抚顺石化公司干法腈纶装置原进口切断刀盘圆环失效的原因 ,认为此种切断刀盘圆环系二维增强结构层压板 ,层间没有纤维增强 ,需要解决由二维增强向三维增强的过渡。给出了改进办法 ,寻求到三维增强的替代材料。同时介绍了机械加工测试及在线实验 相似文献
995.
A new type of modified bismaleimide resin was obtained by copolymerization between tris(allylphenoxy)triazine monomer (TAPT) and an aromatic diamine‐chain‐extension bismaleimide [e.g., 4,4′‐diaminodiphenylmethane (DADPM)‐chain‐extension 4,4′‐bismaleimidodiphenylmethane (BMDPM)]. The new three‐component‐polymer system had good processibility and mechanical properties. Better results were obtained when the weight ratio of TAPT to the DADPM‐chain‐extension BMDPM resin was 30%. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 475–480, 2004 相似文献
996.
提出了一种基于熵权-云模型的方法,借鉴云模型的特点,在构建评价层次结构模型时,采用改进层次分析法结合信息熵确定各评价指标权重,以克服运用模糊层次综合分析法时权重受人为主观判断影响较大和模糊概念会丢失部分不确定性等问题,改进隶属函数对土石坝进行综合评价,并以某均质土石坝为例评价了大坝安全状态,分析表明该方法具有可行性。 相似文献
997.
This paper deals with the problem of H∞ filtering for discrete-time systems with stochastic missing measurements. A new missing measurement model is developed by decomposing the interval of the missing rate into several segments. The probability of the missing rate in each subsegment is governed by its corresponding random variables. We aim to design a linear full-order filter such that the estimation error converges to zero exponentially in the mean square with a less conservatism while the disturbance rejection attenuation is constrained to a given level by means of an H∞ performance index. Based on Lyapunov theory, the reliable filter parameters are characterised in terms of the feasibility of a set of linear matrix inequalities. Finally, a numerical example is provided to demonstrate the effectiveness and applicability of the proposed design approach. 相似文献
998.
This paper studies the consensus of a group of linear dynamic agents with a uniform communication delay and focuses on searching an allowable delay bound. As long as the delay is less than this bound, there exist linear feedback consensus protocols driving the multi-agent system to achieve consensus. Both fixed and switching topology cases are investigated. In both cases, the consensus problem is converted to the robust stability problem of corresponding uncertain state-delayed systems. By using Lyapunov–Krasovskii functional analysis, consensus conditions which contain the feedback gain conditions and delay conditions are proposed for systems over fixed and switching topologies, respectively. Furthermore, allowable delay bounds are obtained for both systems by solving the optimal robust stabilisation problems. Numerical examples are given to illustrate the results. 相似文献
999.
Image clustering methods are efficient tools for applications such as content-based image retrieval and image annotation. Recently, graph based manifold learning methods have shown promising performance in extracting features for image clustering. Typical manifold learning methods adopt appropriate neighborhood size to construct the neighborhood graph, which captures local geometry of data distribution. Because the density of data points’ distribution may be different in different regions of the manifold, a fixed neighborhood size may be inappropriate in building the manifold. In this paper, we propose a novel algorithm, named sparse patch alignment framework, for the embedding of data lying in multiple manifolds. Specifically, we assume that for each data point there exists a small neighborhood in which only the points that come from the same manifold lie approximately in a low-dimensional affine subspace. Based on the patch alignment framework, we propose an optimization strategy for constructing local patches, which adopt sparse representation to select a few neighbors of each data point that span a low-dimensional affine subspace passing near that point. After that, the whole alignment strategy is utilized to build the manifold. Experiments are conducted on four real-world datasets, and the results demonstrate the effectiveness of the proposed method. 相似文献
1000.
Jean‐Rémy Falleri Xavier Blanc Reda Bendraou Marcos Aurélio Almeida da Silva Cédric Teyton 《Software》2014,44(5):621-641
Ensuring models’ consistency is a key concern when using a model‐based development approach. Therefore, model inconsistency detection has received significant attention over the last years. To be useful, inconsistency detection has to be sound, efficient, and scalable. Incremental detection is one way to achieve efficiency in the presence of large models. In most of the existing approaches, incrementalization is carried out at the expense of the memory consumption that becomes proportional to the model size and the number of consistency rules. In this paper, we propose a new incremental inconsistency detection approach that only consumes a small and model size‐independent amount of memory. It will therefore scale better to projects using large models and many consistency rules. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献