全文获取类型
收费全文 | 44186篇 |
免费 | 4888篇 |
国内免费 | 3609篇 |
专业分类
电工技术 | 6155篇 |
综合类 | 4396篇 |
化学工业 | 6883篇 |
金属工艺 | 1523篇 |
机械仪表 | 1606篇 |
建筑科学 | 5017篇 |
矿业工程 | 2209篇 |
能源动力 | 1525篇 |
轻工业 | 5341篇 |
水利工程 | 2445篇 |
石油天然气 | 1778篇 |
武器工业 | 387篇 |
无线电 | 1975篇 |
一般工业技术 | 3801篇 |
冶金工业 | 1161篇 |
原子能技术 | 284篇 |
自动化技术 | 6197篇 |
出版年
2024年 | 282篇 |
2023年 | 896篇 |
2022年 | 1246篇 |
2021年 | 1528篇 |
2020年 | 1715篇 |
2019年 | 1657篇 |
2018年 | 1525篇 |
2017年 | 1657篇 |
2016年 | 1767篇 |
2015年 | 1844篇 |
2014年 | 2545篇 |
2013年 | 2823篇 |
2012年 | 2998篇 |
2011年 | 3244篇 |
2010年 | 2375篇 |
2009年 | 2686篇 |
2008年 | 2409篇 |
2007年 | 2876篇 |
2006年 | 2539篇 |
2005年 | 2189篇 |
2004年 | 1869篇 |
2003年 | 1495篇 |
2002年 | 1245篇 |
2001年 | 1065篇 |
2000年 | 982篇 |
1999年 | 937篇 |
1998年 | 735篇 |
1997年 | 628篇 |
1996年 | 546篇 |
1995年 | 445篇 |
1994年 | 396篇 |
1993年 | 326篇 |
1992年 | 320篇 |
1991年 | 202篇 |
1990年 | 132篇 |
1989年 | 116篇 |
1988年 | 80篇 |
1987年 | 61篇 |
1986年 | 46篇 |
1985年 | 28篇 |
1984年 | 47篇 |
1983年 | 36篇 |
1982年 | 37篇 |
1981年 | 14篇 |
1980年 | 19篇 |
1979年 | 19篇 |
1978年 | 11篇 |
1977年 | 7篇 |
1955年 | 3篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
11.
Docherty Nancy M.; Cohen Alex S.; Nienow Tasha M.; Dinzeo Thomas J.; Dangelmaier Ruth E. 《Canadian Metallurgical Quarterly》2003,112(3):469
This study examined the degree to which different types of communication disturbances in the speech of 48 schizophrenia patients and 28 controls were variable and state related versus stable and traitlike. Clinically rated formal thought disorder and 5 types of referential disturbance showed substantial stability within participants over time. The sixth type of referential disturbance, the vague reference, was not stable over time. Formal thought disorder was associated with the severity of core psychotic symptoms in patients, whereas referential disturbances showed little or no association with positive or negative symptom severity. Furthermore, changes in psychotic symptoms over time were accompanied by corresponding changes in formal thought disorder but not referential disturbances. These results support the idea that some types of referential disturbances are traitlike and may be reflective of vulnerability as well as manifest illness. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
12.
13.
本文对原始状态和在火力发电厂使用不同时间的高这热器102钢管进行了显微组织和相结构变化规律的探讨和研究。显微组织研究表明,102钢管在高温高压下长期运行过程中,使用温度对显微组织和碳化物相有明显影响,而使用时间对其影响不如温度影响强烈。碳化物颗粒图象分析表明,碳化物随着使用时间缓慢长大,而新的碳化物不沉淀,使颗粒总数不断增加,颗粒,间距逐渐缩小。X射线衍射数据证明,钢管在高温长期使用过程中,MC相 相似文献
14.
对于遂昌金矿合理的采场结构参数,目前没有理想的确定方法。本文联系上盘围岩的构造裂隙,矿房的支护形式等提出采场稳定跨度判断指标。经40个采场的检验,值信度达97.5%。 相似文献
15.
How to Control Robots Interacting with Dynamic Environment 总被引:7,自引:0,他引:7
Miomir Vukobratović 《Journal of Intelligent and Robotic Systems》1997,19(2):119-152
The goal of this paper is to shed light on the control problem of constrained robot motion from the aspect of the dynamical nature of the environment with which the robot is in contact. Therefore, the criticism of traditional hybrid control which allows position/force feedback loops to split into independent control with respect to position and force, is not the main point we want to make. Reference to the papers written by the founders of hybrid control and their numerous followers served only to better understand the reason and motivation for suggesting a different approach to control of robots interacting with environment.The paper has a predominantly review character, based on recently published work. It also contains some new, unpublished results in the framework of the unified approach to the position/force control of robots, proposed by the present author and his co-workers. By pointing to the possibility of introducing an environment dynamics in the contact tasks of the machining type, the author emphasizes that the proposed dynamically interactive control can be applied to a completely different class of tasks, in which a contact is made between the system (constructions or structure) and very specific kinds of dynamic environments. 相似文献
16.
介绍了有机EL在稳定性及寿命方面的最新研究动态,着重描述了器件功能层组合的相互接触、阴极、空穴传输层玻璃化温度和驱动条件等对有机EL稳定性和寿命的影响。 相似文献
17.
单元系T—p相图的数学结构 总被引:1,自引:0,他引:1
作者以化学元素的稳定单质为基准,推演出了任意物质M_i(相态Ω)的热力学生成活度{相态Ω)的函数形式:?D_Ω数值的大小体现着相态Ω的热力学相对稳定性.根据集合论原理沿D(稳定性)座标取极大值的方法把物理性质互不连续的各个异相态连结在一起,建立了单元系在T-p面上的优势分布方程(PSDE):■作者以H_2O为实例,计算了T-p相图,与实验相图基本一致. 相似文献
18.
The paper addresses the design of two-level power system stabilizers using an optimal reduced order model whose state variables are torque angles and speeds. The reduced order model retains their physical meaning and is used to design a two-level linear feedback controller that takes into account the realities and constraints of electrical power systems. The two-level control strategy is used, and a global control signal is generated from the output variables to minimize the effect of interactions. The effectiveness of this controller is evaluated and a multimachine system is given as an example to illustrate the advantages of the proposed method. Responses of the system with a two-level scheme and an optimal reduced order scheme are included for comparative analysis. 相似文献
19.
门式脚手架在已建高层建筑外装修中的应用 总被引:1,自引:0,他引:1
介绍门式脚手架在已建高层建筑外排栅中的整体搭设和应用实例。 相似文献
20.
The effect of a range of organic additives on the thermal stability of poly(vinyl chloride), both with and without a chloroparaffin extender, was studied using a number of experimental techniques. Of the additives used the best overall balance was provided by pentaerythritol, which increased stability when the extender was present and had no effect when it was absent. The congo red test emerged as the most suitable technique, being consistent and inexpensive and able to screen several additives simultaneously. Isothermal differential thermal analysis correlated with the congo red test but required more expensive equipment, was time-consuming and demanded good mixing of the poly(vinyl chloride) compound to give reproducible results. Thermogravimetry was not sufficiently sensitive and the heat stability test was the least useful of all. 相似文献