全文获取类型
收费全文 | 39388篇 |
免费 | 4851篇 |
国内免费 | 3789篇 |
专业分类
电工技术 | 4272篇 |
技术理论 | 4篇 |
综合类 | 6856篇 |
化学工业 | 2151篇 |
金属工艺 | 746篇 |
机械仪表 | 3356篇 |
建筑科学 | 2079篇 |
矿业工程 | 1295篇 |
能源动力 | 1638篇 |
轻工业 | 1401篇 |
水利工程 | 1462篇 |
石油天然气 | 1489篇 |
武器工业 | 687篇 |
无线电 | 3202篇 |
一般工业技术 | 2570篇 |
冶金工业 | 983篇 |
原子能技术 | 265篇 |
自动化技术 | 13572篇 |
出版年
2024年 | 163篇 |
2023年 | 444篇 |
2022年 | 847篇 |
2021年 | 916篇 |
2020年 | 1134篇 |
2019年 | 1081篇 |
2018年 | 1026篇 |
2017年 | 1151篇 |
2016年 | 1426篇 |
2015年 | 1535篇 |
2014年 | 2186篇 |
2013年 | 2512篇 |
2012年 | 2804篇 |
2011年 | 3150篇 |
2010年 | 2404篇 |
2009年 | 2644篇 |
2008年 | 2714篇 |
2007年 | 3162篇 |
2006年 | 2937篇 |
2005年 | 2426篇 |
2004年 | 1951篇 |
2003年 | 1703篇 |
2002年 | 1370篇 |
2001年 | 1152篇 |
2000年 | 1022篇 |
1999年 | 861篇 |
1998年 | 695篇 |
1997年 | 501篇 |
1996年 | 412篇 |
1995年 | 351篇 |
1994年 | 316篇 |
1993年 | 205篇 |
1992年 | 171篇 |
1991年 | 133篇 |
1990年 | 111篇 |
1989年 | 116篇 |
1988年 | 68篇 |
1987年 | 37篇 |
1986年 | 27篇 |
1985年 | 24篇 |
1984年 | 24篇 |
1983年 | 19篇 |
1982年 | 12篇 |
1981年 | 13篇 |
1980年 | 10篇 |
1979年 | 11篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1975年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
正则模糊神经网络对一类连续模糊值函数的普遍近似性 总被引:5,自引:0,他引:5
本文讨论了正则模糊神经网络于对定义于区间[0,T0]上连续可减模糊值函数的普遍近似性,在此基础上,证明了[0,T0]上取值为三角形模糊连续递增函数可用正则模糊神经网络逼近到任意精度。 相似文献
182.
基于智能模糊控制策略的有源消声 总被引:3,自引:0,他引:3
有源消声是一种有效的低频噪声控制方法,由于空间有源消声过程具有时变性和非线性,传统的自适应算法不能进行很有效的控制。本文采用智能模糊控制策略,建立了基于智能模糊控制策略的有源消声系统,通过实验与传统自适应控制算法的消声效果作对比分析,证明智能模糊控制器不但控制速度快,易于实现,而且消声效果明显优于后者,具有较大的应用推广价值。 相似文献
183.
Jonas Sjberg Qinghua Zhang Lennart Ljung Albert Benveniste Bernard Delyon Pierre-Yves Glorennec Hkan Hjalmarsson Anatoli Juditsky 《Automatica》1995,31(12):1691-1724
A nonlinear black-box structure for a dynamical system is a model structure that is prepared to describe virtually any nonlinear dynamics. There has been considerable recent interest in this area, with structures based on neural networks, radial basis networks, wavelet networks and hinging hyperplanes, as well as wavelet-transform-based methods and models based on fuzzy sets and fuzzy rules. This paper describes all these approaches in a common framework, from a user's perspective. It focuses on what are the common features in the different approaches, the choices that have to be made and what considerations are relevant for a successful system-identification application of these techniques. It is pointed out that the nonlinear structures can be seen as a concatenation of a mapping form observed data to a regression vector and a nonlinear mapping from the regressor space to the output space. These mappings are discussed separately. The latter mapping is usually formed as a basis function expansion. The basis functions are typically formed from one simple scalar function, which is modified in terms of scale and location. The expansion from the scalar argument to the regressor space is achieved by a radial- or a ridge-type approach. Basic techniques for estimating the parameters in the structures are criterion minimization, as well as two-step procedures, where first the relevant basis functions are determined, using data, and then a linear least-squares step to determine the coordinates of the function approximation. A particular problem is to deal with the large number of potentially necessary parameters. This is handled by making the number of ‘used’ parameters considerably less than the number of ‘offered’ parameters, by regularization, shrinking, pruning or regressor selection. 相似文献
184.
本文对国内外电梯交通配置设计现状及发展趋势作了论述。指出了由统计特性描述进入到采用专家系统和模糊规则的动态特性描述这一总的发展趋势。 相似文献
185.
186.
187.
Jyh-Ping Hsu Shu-Chuan Yang Jung-Chieh Chen 《Journal of the Chinese Institute of Chemical Engineers》2007,38(5-6):409-418
The boundary effect and the presence of a nearby entity on the drag of a rigid entity is investigated by considering the movement of two identical, rigid, coaxial spheres normal to a plane in both a Newtonian and a Carreau fluid at a low to medium large Reynolds number. The parameters key to the phenomenon under consideration, including the nature of the fluid, the separation distance between two spheres, the distance between the near sphere and the plane, and the Reynolds number, on the drag coefficient are discussed. We show that the influence of a boundary on the drag coefficient is more important than that of the nature of a fluid and that of the separation distance between two spheres. The variation of the drag coefficient as a function of Reynolds number for a Carreau fluid is similar to that for a Newtonian fluid. Due to the shear-thinning nature of the former the drag coefficient in the former is smaller than that in the latter. The influence of the index parameter of a Carreau fluid becomes appreciable only if the Carreau number is sufficiently large. Correlations between the drag coefficient and the key parameters of a system are developed for the case when the Reynolds number is smaller than l. 相似文献
188.
本文介绍了模糊技术的发展和现状,以及在相关领域中的应用情况,并且讨论了模糊技术在我国的产业化方向等问题。 相似文献
189.
Anil Kumar 《加拿大化工杂志》1993,71(6):948-954
A new correlation is proposed to correlate the viscosities of salt solutions in aqueous, non-aqueous solvents and their mixtures. The correlation involves two parameters i.e. solvation number and ion-solvent interaction coefficient, which are well-documented quantities in the literature. The proposed correlation has been examined on the experimental viscosity data of salt solutions in aqueous, non-aqueous and their mixtures up to 473 K and 31 MPa pressure. The salts with various ionic charges were employed for testing the proposed correlation. Several non-aqueous solvents like dimethyl sulphoxide, alcohols and formamide were included for the data regression. The viscosities of these solutions can be correlated to within 0.7%. 相似文献
190.
利用模糊评判方法确定张东构造油藏储量计算的可靠程度 总被引:1,自引:0,他引:1
张巨河油田张东构造地处大港滩海交接处,海域部分探井少.目前用油藏描述方法计算的探明储量,其落实程度备受关注.储量落实程度的评价是一个多因素综合评判问题,而且这些因素还分属不同层次.模糊综合评判是应用较为广泛的模糊数学方法之一.该方法建立的综合评判涉及三个要素,即因素集、评判集和单因素评判,由此所构造的模糊评判关系是模糊综合评判的基础.本文用该方法对张东构造沙二段油藏的探明储量落实程度作了尝试性评价. 相似文献