全文获取类型
收费全文 | 5756篇 |
免费 | 786篇 |
国内免费 | 470篇 |
专业分类
电工技术 | 776篇 |
技术理论 | 1篇 |
综合类 | 585篇 |
化学工业 | 271篇 |
金属工艺 | 508篇 |
机械仪表 | 530篇 |
建筑科学 | 409篇 |
矿业工程 | 294篇 |
能源动力 | 114篇 |
轻工业 | 29篇 |
水利工程 | 126篇 |
石油天然气 | 128篇 |
武器工业 | 79篇 |
无线电 | 1281篇 |
一般工业技术 | 480篇 |
冶金工业 | 159篇 |
原子能技术 | 135篇 |
自动化技术 | 1107篇 |
出版年
2024年 | 17篇 |
2023年 | 69篇 |
2022年 | 133篇 |
2021年 | 159篇 |
2020年 | 180篇 |
2019年 | 157篇 |
2018年 | 149篇 |
2017年 | 206篇 |
2016年 | 234篇 |
2015年 | 258篇 |
2014年 | 390篇 |
2013年 | 353篇 |
2012年 | 448篇 |
2011年 | 473篇 |
2010年 | 355篇 |
2009年 | 372篇 |
2008年 | 396篇 |
2007年 | 492篇 |
2006年 | 391篇 |
2005年 | 311篇 |
2004年 | 263篇 |
2003年 | 226篇 |
2002年 | 163篇 |
2001年 | 145篇 |
2000年 | 113篇 |
1999年 | 101篇 |
1998年 | 83篇 |
1997年 | 80篇 |
1996年 | 48篇 |
1995年 | 51篇 |
1994年 | 44篇 |
1993年 | 30篇 |
1992年 | 33篇 |
1991年 | 19篇 |
1990年 | 22篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1976年 | 1篇 |
1965年 | 1篇 |
1964年 | 2篇 |
1960年 | 1篇 |
1956年 | 2篇 |
1955年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有7012条查询结果,搜索用时 15 毫秒
1.
介绍了尿素装置中3起液位仪表失真案例,分析了故障现象和设备工况,确定失真原因,采取了相应的处理措施,解决了仪表故障。 相似文献
2.
ABSTRACTThe RF output power dissipated per unit area is calculated using Runge-Kutta method for the high-moderate-moderate-high (n+-n-p-p+) doping profile of double drift region (DDR)-based impact avalanche transit time (IMPATT) diode by taking different substrate at Ka band. Those substrates are silicon, gallium arsenide, germanium, wurtzite gallium nitride, indium phosphide and 4H-silicon carbide. A comparative study regarding power dissipation ability by the IMPATT using different material is being presented thereby modelling the DDR IMPATT diode in a one-dimensional structure. The IMPATT based on 4H-SiC element has highest power density in the order of 1010 Wm?2 and the Si-based counterpart has lowest power density of order 106 Wm?2 throughout the Ka band. So, 4H-SiC-based IMPATT should be preferable over others for the power density preference based application. This result will be helpful to estimate the power density of the IMPATT for any doping profile and to select the proper element for the optimum design of the IMPATT as far as power density is concerned in the Ka band. Also, we have focused on variation of power density with different junction temperatures and modelled the heat sink with analysis of thermal resistances. 相似文献
3.
研究了由J.Bourgoin和M.Lannoo提出的半导体内Jahn-Teller畸变效应的计算理论。应用Bourgoin和Lannoo的方法研究了含中心氮杂质金刚石结构的Jahn-Teller畸变问题,计算了34C+N簇团的T2模耦合沿%111&晶向的Jahn-Teller畸变效应,结果与实验相符。 相似文献
4.
5.
6.
全尾砂高水固化材料在下向充填采矿法中的应用 总被引:1,自引:1,他引:0
全尾砂高水固化材料是20世纪80年开发出来的矿山新型充填材料,本文简要介绍了全尾砂高固化材料下向进路式充填采矿法的充填工艺技术,并与带钢筋混凝土假顶的下向进路式水硫充填法进行了经济比较。 相似文献
7.
8.
Serran G.; Fernandez Y.; Marshall W. L.; Mann R. E. 《Canadian Metallurgical Quarterly》2003,34(4):368
How critical is the therapeutic alliance in the treatment of sexual offenders? To date such process issues have been neglected in the field of sex offender treatment. This article reviews the literature on the influence on behavior change of therapist features, clients' perceptions, and the therapeutic alliance. Among the many therapist features identified as helpful are empathy, warmth, and being directive and rewarding. Therapists who are aggressively confrontational appear not to foster beneficial changes in their clients. These issues are directly related to treatment issues faced by therapists who work with sexual offenders, such as dealing with cognitive distortions, lack of empathy, and lack of motivation to change. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
10.
A prospective investigation of the impact of childhood sexual abuse on the development of sexuality.
Noll Jennie G.; Trickett Penelope K.; Putnam Frank W. 《Canadian Metallurgical Quarterly》2003,71(3):575
The sexual attitudes and activities of 77 sexually abused and 89 comparison women (mean age=20.41, SD=3.38) were assessed 10 years after disclosure in a longitudinal, prospective study of the long-term effects of childhood sexual abuse. Abused participants were more preoccupied with sex, younger at first voluntary intercourse, more likely to have been teen mothers, and endorsed lower birth control efficacy than comparison participants. When psychological functioning earlier in development was examined, sexual preoccupation was predicted by anxiety, sexual aversion was predicted by childhood sexual behavior problems, and sexual ambivalence (simultaneous sexual preoccupation and sexual aversion) was predicted by pathological dissociation. Findings also indicate that biological father abuse may be associated with greater sexual aversion and sexual ambivalence. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献