全文获取类型
收费全文 | 9538篇 |
免费 | 1224篇 |
国内免费 | 1338篇 |
学科分类
工业技术 | 12100篇 |
出版年
2024年 | 55篇 |
2023年 | 143篇 |
2022年 | 177篇 |
2021年 | 226篇 |
2020年 | 304篇 |
2019年 | 319篇 |
2018年 | 289篇 |
2017年 | 387篇 |
2016年 | 476篇 |
2015年 | 459篇 |
2014年 | 606篇 |
2013年 | 833篇 |
2012年 | 708篇 |
2011年 | 782篇 |
2010年 | 603篇 |
2009年 | 652篇 |
2008年 | 642篇 |
2007年 | 692篇 |
2006年 | 554篇 |
2005年 | 525篇 |
2004年 | 424篇 |
2003年 | 344篇 |
2002年 | 264篇 |
2001年 | 253篇 |
2000年 | 219篇 |
1999年 | 164篇 |
1998年 | 142篇 |
1997年 | 131篇 |
1996年 | 105篇 |
1995年 | 89篇 |
1994年 | 90篇 |
1993年 | 87篇 |
1992年 | 62篇 |
1991年 | 60篇 |
1990年 | 51篇 |
1989年 | 29篇 |
1988年 | 12篇 |
1987年 | 18篇 |
1986年 | 8篇 |
1985年 | 12篇 |
1984年 | 14篇 |
1983年 | 21篇 |
1982年 | 10篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1965年 | 3篇 |
1964年 | 6篇 |
1962年 | 4篇 |
1958年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
根据某面板堆石坝施工期、蓄水初期以及几年来的沉降观测资料,对坝体填筑材料计算参数进行反馈分析,得出了能够反映坝体实际变形的弹塑性应力变形计算参数,有利于今后建立大坝变形预报模型,更准确地把握大坝实时运行状态。 相似文献
2.
Kruk Menno R.; Halász József; Meelis Wout; Haller József 《Canadian Metallurgical Quarterly》2004,118(5):1062
Aggressive behavior induces an adrenocortical stress response, and sudden stressors often precipitate violent behavior. Experiments in rats revealed a fast, mutual, positive feedback between the adrenocortical stress response and a brain mechanism controlling aggression. Stimulation of the aggressive area in the hypothalamus rapidly activated the adrenocortical response, even in the absence of an opponent and fighting. Hypothalamic aggression, in turn, was rapidly facilitated by a corticosterone injection in rats in which the natural adrenocortical stress response was prevented by adrenalectomy. The rapidity of both effects points to a fast, mutual, positive feedback of the controlling mechanisms within the time frame of a single conflict. Such a mutual facilitation may contribute to the precipitation and escalation of violent behavior under stressful conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
Across 2 experiments, a new experimental procedure was used to investigate attentional capture by animal fear-relevant stimuli. In Experiment 1 (N = 34), unselected participants were slower to detect a neutral target animal in the presence of a spider than a cockroach distractor and in the presence of a snake than a large lizard distractor. This result confirms that phylogenetically fear-relevant animals capture attention specifically and to a larger extent than do non-fear-relevant animals. In Experiment 2 (N = 86), detection of a neutral target animal was slowed more in the presence of a feared fear-relevant distractor (e.g., a snake for snake-fearful participants) than in presence of a not-feared fear-relevant distractor (e.g., a spider for snake-fearful participants). These results indicate preferential attentional capture that is specific to phylogenetically fear-relevant stimuli and is selectively enhanced in individuals who fear these animals. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
5.
本文提出励磁电流可自动控制的他励式双高调速系统设计方案。系统在提升特别是在下放重物时,具有较硬的机械性;在负载10-100%的变化范围内,可实现最大偏差Δnmax/nmin100%≤10%,调速范围D≥10;在满载运行条件下,可节约电能80%以上。 相似文献
6.
7.
8.
A Novel Segmentation and Feedback Model for Resolving Contention in Optical Burst Switching 总被引:2,自引:0,他引:2
A novel segmentation and feedback model (SFM) applied to resolve contention is proposed. Simulation and performance analyses show that the SFM effectively avoids contentions in optical burst switching (OBS). The long delay time of deflection routing and the immature technology of wavelength converters and optical buffers are not deployed in the SFM. The SFM does not only realize fast switching but also allows preemption by higher priority bursts. 相似文献
9.
行激励级电路的设计是完全为行输出级服务的,它实质上是行输出级电路设计的一个重要而不可分割的组成部分。因此行激励级电路的设计,自然采用了从显象管偏转线圈和行输出管到激励变压器和行激励级的倒推设计法。 相似文献
10.
This paper presents a highly stable steady-state torque control system with a feedback of a secondary current signal. The torque control system is constructed with a feedback of the secondary current (I2) signal using a quick response magnetic-field sensor constructed with an amorphous core multivibrator bridge, which can solve the secondary resistance change problem for temperature variation in the IM. Moreover, we added a state feedback to the system to improve the response speed for the unit step function of a torque order. The I2 sensor method has advantages especially at a low-speed range, in which conventional method using an integrator shows control errors. 相似文献