全文获取类型
收费全文 | 155597篇 |
免费 | 15351篇 |
国内免费 | 9225篇 |
专业分类
电工技术 | 12156篇 |
技术理论 | 3篇 |
综合类 | 12340篇 |
化学工业 | 22587篇 |
金属工艺 | 9941篇 |
机械仪表 | 10805篇 |
建筑科学 | 12245篇 |
矿业工程 | 5105篇 |
能源动力 | 4489篇 |
轻工业 | 10291篇 |
水利工程 | 3656篇 |
石油天然气 | 7766篇 |
武器工业 | 1877篇 |
无线电 | 18542篇 |
一般工业技术 | 16388篇 |
冶金工业 | 6881篇 |
原子能技术 | 1888篇 |
自动化技术 | 23213篇 |
出版年
2024年 | 637篇 |
2023年 | 2025篇 |
2022年 | 4361篇 |
2021年 | 6092篇 |
2020年 | 4579篇 |
2019年 | 3657篇 |
2018年 | 4073篇 |
2017年 | 4825篇 |
2016年 | 4516篇 |
2015年 | 6630篇 |
2014年 | 8223篇 |
2013年 | 9695篇 |
2012年 | 11622篇 |
2011年 | 12281篇 |
2010年 | 11569篇 |
2009年 | 11281篇 |
2008年 | 10925篇 |
2007年 | 10468篇 |
2006年 | 9593篇 |
2005年 | 8067篇 |
2004年 | 5800篇 |
2003年 | 5089篇 |
2002年 | 5081篇 |
2001年 | 4454篇 |
2000年 | 3178篇 |
1999年 | 2678篇 |
1998年 | 1656篇 |
1997年 | 1475篇 |
1996年 | 1263篇 |
1995年 | 1005篇 |
1994年 | 810篇 |
1993年 | 579篇 |
1992年 | 437篇 |
1991年 | 349篇 |
1990年 | 287篇 |
1989年 | 239篇 |
1988年 | 175篇 |
1987年 | 121篇 |
1986年 | 99篇 |
1985年 | 41篇 |
1984年 | 46篇 |
1983年 | 26篇 |
1982年 | 33篇 |
1981年 | 24篇 |
1980年 | 28篇 |
1979年 | 13篇 |
1978年 | 10篇 |
1976年 | 7篇 |
1959年 | 10篇 |
1951年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
时尚与传统交织的当下,我们已经迎来12年一遇的传统农历新年--金猪年的到来,环顾大街小巷,到处都充满了喜气祥和的节日气氛,采购礼品也被提上了日程. 相似文献
62.
StructureandMagneticPropertiesofLaCo_(13-X)M_XIntermetallicCompoundsWUJianMin;LIFeng;TAILiChiandZHEMGQunStructureandMagneticP... 相似文献
63.
Centralized and distributed automated guided vehicle system (AGVS) models for materials handling, and the model for part processing are integrated into a single coherent model. This formulation can be used to collectively schedule and control the entire flexible manufacturing system (FMS) as opposed to the traditional separate scheduling of part processing and material handling. The two AGVS models are based on Petri nets and can be directly used in the scheduling method that uses Petri nets for formulation and heuristic search for solution. This method employs a global search to seek the optimal operation of an entire FMS. Scheduling examples are presented and the method compares favorably with the results simulated using heuristic dispatch rules 相似文献
64.
Jyh-Ming Wang Sung-Chuan Fang Wu-Shiung Feng 《Solid-State Circuits, IEEE Journal of》1994,29(7):780-786
Two new methods are proposed to implement the exclusive-OR and exclusive-NOR functions on the transistor level. The first method uses non-complementary signal inputs and the least number of transistors. The other one improves the performance of the prior method but two more transistors are utilized. Both of them have been fully simulated by HSPICE on a SUN SPARC 2 workstation 相似文献
65.
A powerful concept to cope with resource limitations and information redundancy in wireless sensor networks is the use of collaboration groups to distill information within the network and suppress unnecessary activities. When the phenomena to be monitored have large geographical extents, it is not obvious how to define these collaboration groups. This article presents the application of geometric duality to form such groups for sensor selection and non-local phenomena tracking. Using a dual-space transformation, which maps a non-local phenomenon (e.g., the edge of a half-plane shadow) to a single point in the dual space and maps locations of distributed sensor nodes to a set of lines that partitions the dual space, one can turn off the majority of the sensors to achieve resource preservation without losing detection and tracking accuracy. Since the group so defined may consist of nodes that are far away in physical space, we propose a hierarchical architecture that uses a small number of computationally powerful nodes and a massive number of power constrained motes. By taking advantage of the continuity of physical phenomena and the duality principle, we can greatly reduce the power consumption in non-local phenomena tracking and extend the lifetime of the network. 相似文献
66.
坐标旋转法的收敛性,误差估计及扩展 总被引:1,自引:0,他引:1
谷峰 《数值计算与计算机应用》2006,27(1):1-8
本文通过推广正规序列的定义,得到一个不等式,由此证明了统一计算初等函数数值的坐标旋转法的收敛性,作了误差估计,并拓广了所计算的函数范围,成为快速计算所有初等函数的统一算法. 相似文献
67.
It is demonstrated for the first time that long nanowires with radii as small as 30 nm can be manufactured with a conventional coupler fabrication rig. The temporal deterioration of nanowire optical properties has been studied and correlated with its mechanical behaviour. The original transmission properties have been restored by a post-fabrication treatment. 相似文献
68.
介绍了平煤集团围绕以人为本的理念开展的提升理念、创新管理、加大投入和提高员工素质等一系列安全活动,为进一步抓好安全生产打下了坚实基础。 相似文献
69.
70.
A parametric interpolator with confined chord errors, acceleration and deceleration for NC machining 总被引:6,自引:0,他引:6
Tsehaw Yong Author Vitae Author Vitae 《Computer aided design》2003,35(13):1249-1259
Parametric interpolation has many advantages over linear interpolation in machining curves. Real time parametric interpolation research so far has addressed achieving a uniform feed rate, confined chord errors and jerk limited trajectory planning. However, simultaneous consideration of confined chord errors that respect the acceleration and deceleration capabilities of the machine has not been attempted. In this paper, the offline detection of feed rate sensitive corners is proposed. The velocity profile in these zones is planned so that chord errors are satisfied while simultaneously accommodating the machine's acceleration and deceleration limits. Outside the zone of the feed rate sensitive corners, the feed rate is planned using the Taylor approximation. Simulation results indicate that the offline detection of feed rate sensitive corners improves parametric interpolation. For real time interpolation, the parametric curve information can be augmented with the detected feed rate sensitive corners that are stored in 2×2 matrices. 相似文献