全文获取类型
收费全文 | 7559篇 |
免费 | 1231篇 |
国内免费 | 912篇 |
专业分类
电工技术 | 355篇 |
综合类 | 1049篇 |
化学工业 | 145篇 |
金属工艺 | 221篇 |
机械仪表 | 538篇 |
建筑科学 | 976篇 |
矿业工程 | 263篇 |
能源动力 | 70篇 |
轻工业 | 247篇 |
水利工程 | 175篇 |
石油天然气 | 541篇 |
武器工业 | 75篇 |
无线电 | 713篇 |
一般工业技术 | 380篇 |
冶金工业 | 221篇 |
原子能技术 | 42篇 |
自动化技术 | 3691篇 |
出版年
2024年 | 22篇 |
2023年 | 78篇 |
2022年 | 187篇 |
2021年 | 214篇 |
2020年 | 289篇 |
2019年 | 248篇 |
2018年 | 247篇 |
2017年 | 277篇 |
2016年 | 334篇 |
2015年 | 317篇 |
2014年 | 477篇 |
2013年 | 468篇 |
2012年 | 655篇 |
2011年 | 742篇 |
2010年 | 556篇 |
2009年 | 583篇 |
2008年 | 606篇 |
2007年 | 650篇 |
2006年 | 508篇 |
2005年 | 443篇 |
2004年 | 378篇 |
2003年 | 326篇 |
2002年 | 220篇 |
2001年 | 186篇 |
2000年 | 161篇 |
1999年 | 112篇 |
1998年 | 68篇 |
1997年 | 65篇 |
1996年 | 44篇 |
1995年 | 45篇 |
1994年 | 50篇 |
1993年 | 24篇 |
1992年 | 25篇 |
1991年 | 23篇 |
1990年 | 11篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1955年 | 1篇 |
排序方式: 共有9702条查询结果,搜索用时 15 毫秒
11.
It has been reported that it is harder to switch to a strong, well-practiced task from a weaker, less-practiced task than vice versa. Three experiments replicated this surprising asymmetry and investigated how it is affected by a reduction in interference between tasks. Experiment 1 progressively delayed the onset of the stimulus attribute associated with the stronger task. Experiments 2 and 3 separated the response sets of the tasks. Both manipulations reduced, without eliminating, interference of the stronger with the weaker task but reversed the asymmetry of switch costs, resulting in a larger cost of switching to the weaker task. The results are interpreted in terms of a model of the interactions between control input, task strength, and task priming. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
12.
提高定制产品物料需求预测准确性是提高企业竞争能力的必由之路。通过某公司提高定制产品物料需求预测准确性的具体项目实践,介绍了关于提高物料需求预测准确性的具体措施。通过建立一种能为各部门所共同接受的产品语言来加强各部门的信息交流,并减少从客户的实际需求到物料预测之间的中间环节来提高整个物料预测的准确性,并以实例验证其有效性。 相似文献
13.
The engineering and management of human safety is an important societal objective that includes extensive efforts by governments, both legislative and administrative, to enhance the health and safety of the public. Although the achievement of safety goals depend primarily on individuals and organizations responsible for safety, much support is drawn from expertise in diverse scientific and engineering disciplines. The activities range from structural safety (dams, tunnels, bridges to tall buildings) to safe operation of hazardous industrial installations (energy generation facilities, LNG terminals, petrochemical plants) to transportation systems (airline, rail, car safety) to technologies designed to minimize adverse impacts on the environment. All these activities are crucially concerned with risk: with the likelihood and the probable effects of various measures on life and health. We have developed a unified rationale and a clear basis for effective strategic management of risk across diverse sectors. Safety is an important objective in society but it is not the only one. The allocation of society's resources devoted to safety must be continually appraised in light of competing needs, because there is a limit on the resources that can be expended to extend life. The paper presents the Life Quality Index (LQI) as a tool for the assessment of risk reduction initiatives that would support the public interest and enhance safety and quality of life. The paper provides an intuitive reformulation of the LQI as equivalent to a valid utility function that is consistent with the principles of rational decision analysis. The LQI is further refined to consider the issues of discounting of life years, competing background risks, and population age and mortality distribution. The LQI is applied to quantify the societal willingness-to-pay, which is an acceptable level of public expenditure in exchange for a reduction in the risk of death that results in improved life-quality. 相似文献
14.
化学结构式的拓扑描述 总被引:1,自引:0,他引:1
化学结构式的拓扑描述,是化学信息计算机化的手段之一。这里系统地建立了一整套的连接表(三类:紧缩连接表、冗余连接表、和连接方阵),用来进行结构式中原子之间连接关系的拓扑描述,对分子结构进行数值化。同时,阐述了连接表唯一化的方法,并介绍了不同类型连接表之间的转换关系和还原为平面结构式图形的绘图程序。 相似文献
15.
16.
17.
Keh-Shin Lii 《时间序列分析杂志》1985,6(3):153-169
Abstract. A distributed lag model with a rational transfer function is considered. We have demonstrated that the C -table can be used to determine the orders of the rational transfer function and the Padé table can be used to estimate the parameters of an identifiable transfer function. In case the model is not uniquely identified, the C -table reduces possible competing models to only a few for further examination. Padé approximant gives consistent initial values for possibly more efficient iterative procedures to estimate the coefficients of the identified model. Some asymptotic results on the estimation of the C -table and the Padé table are given. A few examples are presented to demonstrate the effectiveness of the method. 相似文献
18.
19.
属性识别理论在黄前水库水质评价中的应用 总被引:6,自引:0,他引:6
本文根据属性识别理论,探讨了水库水质的综合评价模型,应用此模型对黄前水库的水质进行评价,结果与灰色关联度法基本相同,比较符合实际情况。同时该方法简单、易懂,更适合于有标准的系统质量评价问题。 相似文献
20.