全文获取类型
收费全文 | 50412篇 |
免费 | 5234篇 |
国内免费 | 2865篇 |
专业分类
电工技术 | 4095篇 |
技术理论 | 4篇 |
综合类 | 6435篇 |
化学工业 | 3247篇 |
金属工艺 | 1103篇 |
机械仪表 | 2780篇 |
建筑科学 | 5915篇 |
矿业工程 | 2484篇 |
能源动力 | 1686篇 |
轻工业 | 5392篇 |
水利工程 | 2757篇 |
石油天然气 | 5510篇 |
武器工业 | 1006篇 |
无线电 | 2986篇 |
一般工业技术 | 3404篇 |
冶金工业 | 1681篇 |
原子能技术 | 458篇 |
自动化技术 | 7568篇 |
出版年
2024年 | 267篇 |
2023年 | 731篇 |
2022年 | 1356篇 |
2021年 | 1649篇 |
2020年 | 1773篇 |
2019年 | 1454篇 |
2018年 | 1432篇 |
2017年 | 1570篇 |
2016年 | 1960篇 |
2015年 | 2003篇 |
2014年 | 3295篇 |
2013年 | 3008篇 |
2012年 | 3899篇 |
2011年 | 3997篇 |
2010年 | 2904篇 |
2009年 | 3021篇 |
2008年 | 2766篇 |
2007年 | 3462篇 |
2006年 | 3027篇 |
2005年 | 2721篇 |
2004年 | 2174篇 |
2003年 | 1879篇 |
2002年 | 1425篇 |
2001年 | 1255篇 |
2000年 | 1016篇 |
1999年 | 875篇 |
1998年 | 650篇 |
1997年 | 606篇 |
1996年 | 476篇 |
1995年 | 400篇 |
1994年 | 297篇 |
1993年 | 236篇 |
1992年 | 161篇 |
1991年 | 160篇 |
1990年 | 104篇 |
1989年 | 114篇 |
1988年 | 64篇 |
1987年 | 41篇 |
1986年 | 36篇 |
1985年 | 23篇 |
1984年 | 29篇 |
1983年 | 31篇 |
1982年 | 18篇 |
1981年 | 15篇 |
1980年 | 8篇 |
1979年 | 12篇 |
1978年 | 11篇 |
1977年 | 11篇 |
1959年 | 9篇 |
1956年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
DING Jun 《数字社区&智能家居》2008,(14)
本文主要针对目前网站上常用的查询系统所存在的某些常见问题而提出了一种新的查询设计思路,这种新的设计思路主要是在客户端利用JavaScript脚本语言对用户设置的查询条件进行预处理,让用户设置的条件以两种形式出现在系统中,一种形式方便方便用户阅读和理解,另一种形式用于真正的数据查询;此外,通过脚本语言将用户设置的查询条件保存于页面上列表中,用户可以随意组合现有的条件形成更为复杂的查询条件;同时用户也可以在列表中随意选择某个条件执行数据查询。 相似文献
62.
Robert Cummins 《Minds and Machines》1991,1(1):31-42
In response to Michael Morris, I attempt to refute the crucial second premise of the argument, which states that the formality condition cannot be satisfied non-stipulatively in computational systems. I defend the view of representation urged in Meaning and Mental Representation against the charge that it makes content stipulative and therefore irrelevant to the explanation of cognition. Some other reservations are expressed. 相似文献
63.
刘树国 《沈阳工程学院学报(自然科学版)》2012,8(2):116-121
由于施工放样原因,双曲线冷却塔风筒发生移位变形,筒壁出现初始几何缺陷,偏差超出规范允许值,造成冷却塔应力状态改变.利用冷却塔专用计算软件对冷却塔结构进行静力计算,根据计算的内力对强度进行验算,分析初始几何缺陷对冷却塔应力状态的影响,评价冷却塔结构安全性及是否需要进行加固处理,并对冷却塔后期维护提出建议. 相似文献
64.
《国际计算机数学杂志》2012,89(8):1366-1374
In this study we are concerned with the local convergence of a Newton-type method introduced by us [I.K. Argyros and D. Chen, On the midpoint iterative method for solving nonlinear equations in Banach spaces, Appl. Math. Lett. 5 (1992), pp. 7–9.] for approximating a solution of a nonlinear equation in a Banach space setting. This method has also been studied by Homeier [H.H.H. Homeier, A modified Newton method for rootfinding with cubic convergence, J. Comput. Appl. Math. 157 (2003), pp. 227–230.] and Özban [A.Y. Özban, Some new variants of Newton's method, Appl. Math. Lett. 17 (2004), pp. 677–682.] in real or complex space. The benefits of using this method over other methods using the same information have been explained in [I.K. Argyros, Computational theory of iterative methods, in Studies in Computational Mathematics, Vol. 15, C.K. Chui and L. Wuytack, eds., Elsevier Science Inc., New York, USA, 2007.; I.K. Argyros and D. Chen, On the midpoint iterative method for solving nonlinear equations in Banach spaces, Appl. Math. Lett. 5 (1992), pp. 7–9.; H.H.H. Homeier, A modified Newton method for rootfinding with cubic convergence, J. Comput. Appl. Math. 157 (2003), pp. 227–230.; A.Y. Özban, Some new variants of Newton's method, Appl. Math. Lett. 17 (2004), pp. 677–682.]. Here, we give the convergence radii for this method under a type of weak Lipschitz conditions proven to be fruitful by Wang in the case of Newton's method [X. Wang, Convergence of Newton's method and inverse function in Banach space, Math. Comput. 68 (1999), pp. 169–186 and X. Wang, Convergence of Newton's method and uniqueness of the solution of equations in Banach space, IMA J. Numer. Anal. 20 (2000), pp. 123–134.]. Numerical examples are also provided. 相似文献
65.
《国际计算机数学杂志》2012,89(5):1097-1121
This paper presents the mechanical quadrature methods (MQMs) for solving the boundary integral equations of steady-state anisotropic heat conduction equation on the smooth domains and polygons, respectively. The costless and high-accurate Sidi–Israeli quadrature formula are applied to deal with the integrals in which the kernels have a logarithmic singularity. Especially, the Sidi transformation is used for the polygon cases in order to obtain a rapid convergence by degrading the singularity at the corners on the boundary. The convergence and stability of the MQMs solution are proved based on Anselone's collective compact theory. In addition, asymptotic error expansion of the MQMs shows that the approximation order is of O(h3), where h is the partition size of the boundary. Finally, numerical examples are tested and results verify the theoretical analysis. 相似文献
66.
为了提高评教数据在教学管理中的利用率,更加有效地为学校的决策服务。本文在研究了数据仓库、OLAP分析、数据挖掘技术的基础上,设计和实现了评教系统,实现了对评教数据的综合分析和深入挖掘。使用该系统后,教学管理部门改变了对评教数据的使用方式,提高了利用率,认识和理解更加深人和全面。 相似文献
67.
中央部门机关政府采购绩效评价,应该以党和国家关于缋效管理和政府采购的一系列重要文件为指导,针对政府采购工作全过程,以绩效目标为牵引,以绩效指标和评价标准为重点,以完善的评价组织方法为推动力,贴近实际、注重实效,按照事前、事中、事后三个阶段,客观评定中央部门机关政府采购工作投入产出比,以及工作的效益和效率情况,为政府采购工作的开展提供借鉴. 相似文献
68.
69.
《Ergonomics》2012,55(9):1394-1406
As with most machines, the integral safety mechanism on firearms is vital to injury or fatality free operation. Presently, there is little or no standardisation in the design of these mechanisms. In this investigation, five existing designs found on both military and commercial rifles were evaluated ergonomically to determine the most effective characteristics for incorporation into future designs. The designs were evaluated experimentally on ease of use, visual effectiveness and operational impact. Three groups, representing a total of 30 subjects with widely varying experience, were selected. Results strongly suggest that safeties whose actuators are mounted within easy reach of the trigger finger are preferred and have the least operational impact. Subjects also preferred and were more adept at recognising safety status when the indicator was located on the receiver/barrel along the normal line of sight. Subjects more often correctly identified safety status when the indicator utilised colouring, was clearly marked and/or was in the normal line of sight. The results of this research prove that ergonomics can contribute to the understanding of firearm safety dynamics. The two essential components of safety mechanism design identified in this investigation, unambiguous status visibility and impact-free operation, are also likely to have implications in non-firearm safety mechanism design. This is particularly true for devices whose inadvertent operation can cause injury, as well as systems in which operational effectiveness can be jeopardised when attentiveness or operational control are lost in the process of actuating a poorly designed safety mechanism. 相似文献
70.
感官评定是控制烹饪菜品质量的重要途径之一,文章以川菜代表性菜品——鱼香肉丝为评定对象,选取色、香、味、形、质等因素并设置合理的权重,对同一试验小组A、B、C、D、E等5道鱼香肉丝菜肴进行模糊数学综合评定。试验结果表明,用模糊数学综合评判法,能客观而准确地区分出不同烹饪菜肴的差异程度和等级,即5道鱼香肉丝感官评定等级从高到低为:C〉D〉E〉A〉B。 相似文献