全文获取类型
收费全文 | 3722篇 |
免费 | 192篇 |
国内免费 | 25篇 |
专业分类
电工技术 | 53篇 |
综合类 | 30篇 |
化学工业 | 599篇 |
金属工艺 | 65篇 |
机械仪表 | 63篇 |
建筑科学 | 160篇 |
矿业工程 | 395篇 |
能源动力 | 41篇 |
轻工业 | 392篇 |
水利工程 | 521篇 |
石油天然气 | 51篇 |
无线电 | 182篇 |
一般工业技术 | 374篇 |
冶金工业 | 447篇 |
原子能技术 | 37篇 |
自动化技术 | 529篇 |
出版年
2023年 | 33篇 |
2022年 | 80篇 |
2021年 | 85篇 |
2020年 | 75篇 |
2019年 | 58篇 |
2018年 | 86篇 |
2017年 | 70篇 |
2016年 | 78篇 |
2015年 | 91篇 |
2014年 | 87篇 |
2013年 | 191篇 |
2012年 | 174篇 |
2011年 | 200篇 |
2010年 | 178篇 |
2009年 | 141篇 |
2008年 | 163篇 |
2007年 | 136篇 |
2006年 | 100篇 |
2005年 | 139篇 |
2004年 | 225篇 |
2003年 | 294篇 |
2002年 | 305篇 |
2001年 | 280篇 |
2000年 | 51篇 |
1999年 | 35篇 |
1998年 | 56篇 |
1997年 | 41篇 |
1996年 | 38篇 |
1995年 | 28篇 |
1994年 | 37篇 |
1993年 | 35篇 |
1992年 | 29篇 |
1991年 | 22篇 |
1990年 | 24篇 |
1989年 | 25篇 |
1988年 | 17篇 |
1987年 | 19篇 |
1986年 | 14篇 |
1985年 | 17篇 |
1984年 | 21篇 |
1983年 | 17篇 |
1982年 | 23篇 |
1981年 | 18篇 |
1980年 | 14篇 |
1979年 | 22篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1975年 | 6篇 |
1958年 | 6篇 |
排序方式: 共有3939条查询结果,搜索用时 15 毫秒
11.
传统对辊破碎机最普遍的两个特点是破碎比小和磨损率高,因而,使其不能经常在选矿流程中得到应用,它的很多优点却一直被人们所忽视。本文介绍一种被称为辊筒非圆柱形辊式破碎机(缩写为NCRC破碎机),其目的是克服传统对辊破碎机的以上缺点。NCRC破碎机具有两个交替排列的平面-凸圆面辊筒和平面-凹圆面辊筒组成,这两个奇特的辊筒外形增大了矿粒与辊筒之间的啮角,使得NCRC破碎机的破碎比比传统对辊机大,NCRC破碎机样机试验表明,即使对很硬的矿石也能获得破碎比大于10:1的结果。此外,幅地NCRC破碎机的破碎过程为对辊破碎机和颚式破碎机两种的联合作用,因而这种辊面外形变化的新式辊筒的磨损率得到降低。 相似文献
12.
13.
14.
Action calculi, which generalise process calculi such as Petri nets, π-calculusand ambient calculus, have been presented
in terms of action graphs. We here offer linear action graphs as a primitive basis for action calculi. This paper presents the category of embeddings of undirected linear
action graphs without nesting, using a novel form of graphical reasoning which simplifies some otherwise complex manipulations
in regular algebra. The results are adapted in a few lines to directed graphs. This work is part of a long-term search for
a uniform behavioural theory for process calculi.
Received October 2000 / Accepted in revised form April 2001 相似文献
15.
坦努尔坝是约旦的第一座RCC坝。该坝RCC铺筑采用斜层施工,提高工数50%。大坝上游面,下游台阶,阶梯式溢洪道,止水面以及RCC与坝肩石灰岩的交界面均采用GE-RCC。质量控制测试数据表明,该坝达到了国际大坝委员会会刊不久将发表的RCC坝质量标准的优良等级。 相似文献
16.
巴西的一个重要电力公司COPEL最近开发了一个水电站高级控制系统,这是在电力部门经受重大变革时期,提高水电竞争力的里程碑。 相似文献
17.
Krenz William Robin Michael Barez Shirin Stark Lawrence 《IEEE transactions on bio-medical engineering》1985,(10):817-825
A model of the pathways controlling the size of the human pupil is presented. Computer simulation of this model demonstrates the role played by each of the elements in the pupil pathways. Simulations of the effects of drugs and a few common abnormalities in the system also help to illustrate the workings of the internal processes. Computer models of this type can be used as teaching aids or as tools for testing of hypotheses regarding the system. 相似文献
18.
Nusslock Robin; Abramson Lyn Y.; Harmon-Jones Eddie; Alloy Lauren B.; Hogan Michael E. 《Canadian Metallurgical Quarterly》2007,116(1):105
On the basis of the behavioral approach system (BAS) dysregulation theory of bipolar disorder, this study examined the relation between occurrence of a BAS activation-relevant life event--goal striving--and onset of hypomanic and depressive episodes and symptoms. In particular, the authors examined the relation between preparing for and completing final exams (a goal-striving event) and onset of bipolar spectrum episodes and symptoms in college students with bipolar II disorder or cyclothymia (i.e., "soft" bipolar spectrum conditions). One hundred fifty-nine individuals with either a bipolar spectrum disorder (n=68) or no major affective psychopathology (controls; n=91) were further classified on the basis of whether they were college students (i.e., completed final exams). Consistent with the BAS dysregulation theory, preparing for and completing final exams was associated with an increase in hypomanic but not depressive episodes and symptoms in individuals with a soft bipolar spectrum diagnosis. Furthermore, self-reported BAS sensitivity moderated the presence of certain hypomanic symptoms during final exams. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
19.
Mulcahy Nicholas J.; Call Josep; Dunbar Robin I. M. 《Canadian Metallurgical Quarterly》2005,119(1):23
Two important elements in problem solving are the abilities to encode relevant task features and to combine multiple actions to achieve the goal. The authors investigated these 2 elements in a task in which gorillas (Gorilla gorilla) and orangutans (Pongo pygmaeus) had to use a tool to retrieve an out-of-reach reward. Subjects were able to select tools of an appropriate length to reach the reward even when the position of the reward and tools were not simultaneously visible. When presented with tools that were too short to retrieve the reward, subjects were more likely to refuse to use them than when tools were the appropriate length. Subjects were proficient at using tools in sequence to retrieve the reward. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
20.
在西西伯利亚俄罗斯油田开展了注凝析油开发稠油的研究,现场实验结果表明,注入25%的凝析油,可使其混合液粘度达到原高粘油粘度的1/60,以俄罗斯油田为例,探讨了注凝析油矿场试验的可行性,预测了凝析油的用量和可能产出的油量,并对原油外输提出了一系列更换工艺设备的要求。 相似文献