全文获取类型
收费全文 | 109151篇 |
免费 | 3220篇 |
国内免费 | 1507篇 |
专业分类
电工技术 | 2216篇 |
技术理论 | 3篇 |
综合类 | 3919篇 |
化学工业 | 15633篇 |
金属工艺 | 6470篇 |
机械仪表 | 4627篇 |
建筑科学 | 4459篇 |
矿业工程 | 1297篇 |
能源动力 | 1774篇 |
轻工业 | 5226篇 |
水利工程 | 1681篇 |
石油天然气 | 1781篇 |
武器工业 | 206篇 |
无线电 | 12211篇 |
一般工业技术 | 19458篇 |
冶金工业 | 3712篇 |
原子能技术 | 516篇 |
自动化技术 | 28689篇 |
出版年
2024年 | 94篇 |
2023年 | 423篇 |
2022年 | 700篇 |
2021年 | 1099篇 |
2020年 | 854篇 |
2019年 | 650篇 |
2018年 | 15086篇 |
2017年 | 14097篇 |
2016年 | 10611篇 |
2015年 | 1570篇 |
2014年 | 1404篇 |
2013年 | 1668篇 |
2012年 | 4732篇 |
2011年 | 11050篇 |
2010年 | 9816篇 |
2009年 | 6969篇 |
2008年 | 8129篇 |
2007年 | 9168篇 |
2006年 | 1493篇 |
2005年 | 2494篇 |
2004年 | 2007篇 |
2003年 | 1946篇 |
2002年 | 1325篇 |
2001年 | 725篇 |
2000年 | 898篇 |
1999年 | 795篇 |
1998年 | 671篇 |
1997年 | 519篇 |
1996年 | 544篇 |
1995年 | 395篇 |
1994年 | 329篇 |
1993年 | 257篇 |
1992年 | 218篇 |
1991年 | 155篇 |
1990年 | 86篇 |
1989年 | 88篇 |
1988年 | 78篇 |
1987年 | 38篇 |
1986年 | 33篇 |
1968年 | 43篇 |
1967年 | 33篇 |
1966年 | 42篇 |
1965年 | 44篇 |
1960年 | 30篇 |
1959年 | 35篇 |
1958年 | 37篇 |
1957年 | 36篇 |
1956年 | 34篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Three interesterified vegetable oils (IVOs) prepared from palm, cottonseed, and olive oil, respectively, have been studied for application to Frankfurters. Beef fat (10%) was replaced by one of the IVOs at 20, 60 or 100%. Fatty acid composition of the lipid fraction in the Frankfurters and saturated/unsaturated ratios were established for all batches. We found that total or partial replacement of beef fat by IVOs did not lead to significant changes in appearance, colour, texture, flavour or sensory score. We conclude that IVOs may be successfully applied as beef fat substitutes in Frankfurters. 相似文献
82.
J-M Choe 《欧洲信息系统杂志》2002,11(2):142-158
This study empirically examined the organisational learning effects of the nonfinancial performance information provided by management accounting information systems (MAISs) under advanced manufacturing technology (AMT). In this study, a target costing system and the frequent and quick reporting of information were considered the facilitators of learning. First, we examined the relationships between AMT level and the amount of nonfinancial performance information produced by MAISs. The empirical results showed that there are significant positive relationships between the level of AMT and nonfinancial performance information. With a systems approach, we also proved the impact of the relationships among AMT levels, nonfinancial performance information and learning facilitators on the organisational performance of a firm. The results of our research suggest that under a high level of AMT, for the provision of information to result in an increase of performance through organisational learning, a target costing system must be introduced and a large amount of information should be provided frequently and quickly. The results of this study also showed that although AMT level may be low, fairly well-arranged facilitators and a moderately large amount of information may be necessary for the improvement of performance. In conclusion, effective organisational learning depends on the provision of relevant information as well as efficient learning support mechanisms. 相似文献
83.
GPS硬件由主机和副机两部分组成,本文以Sercel公司生产的NR102K型GPS全球定位系统为例,介绍了其主机和副机在野外施工中的常见故障和解决方法,具有一定的实用性。 相似文献
84.
85.
86.
研究开发出一种遥操作工程机器人系统,可以应用于诸如火灾现场的修复作业等广阔的领域.该系统由伺服控制的工程机器人、2根从远处操纵工程机器人的操纵杆、视频系统和6自由度运动模拟器组成.操作者坐于座椅上,座椅固定于运动模拟器的上方. 该系统需要解决的一个关键问题是如何使操纵者高质量地获得工作现场的临场运动感觉. 提出了一种6自由度临场运动感觉反馈方法,其信号源来自工程机器人上安装的6个加速度传感器. 该方法的有效性已为实验所证明,即应用6自由度运动模拟器不但可以高质量地模拟工程机器人单个自由度的运动:滚动、俯仰、转动以及前后、左右、上下的平移,而且可以高质量地模拟工程机器人的各种复合运动. 相似文献
87.
88.
PENGLiming MAOXiemin XUKuangdi DINGWenjiang 《稀有金属(英文版)》2002,21(1):62-66
In order to develop a new type of contact cable with high strength and high electrical conductivity, Cu-Cr alloy series were selected as materials and Cu-Cr alloy castings were produced by means of directional solidification continuous casting (DSCC) process. The results show that the fibrillar strengthening phase, 13-Cr, orderly arranges among the copper matrix phase along the wire direction; and a microstructure of in-situ composite forms, which retains the basic property of good conductivity of the copper matrix and meanwhile obtains the strengthening effect of [3-Cr phase. The production technology as well as the mechanical property, electrical property, and synthetic property of the in-situ composite contact cables was discussed. 相似文献
89.
Less may not be more,but it still counts: The state of social capital in Yeoville,Johannesburg 总被引:2,自引:2,他引:0
Kirsten Harrison 《Urban Forum》2002,13(1):67-84
90.
Yanqiu Shao Jiqing Han Ting Liu Yongzhen Zhao 《International Journal of Speech Technology》2007,10(1):45-55
In real speech, not like lexical words (LWs), prosodic words (PWs) are basic rhythmic units. The naturalness of a Text-to-Speech
(TTS) system is directly influenced by the segmentation of the PWs. Most of the PWs are the combination of several LWs. In
this paper, three Lexical Combination Models are proposed to combine LWs into PWs, including a Directed Acyclic Graph Model,
a Segmentation Model and a Markov Model (MM). To cope with the situation where some long LWs should be segmented into two
or more PWs, a Lexical Split Model (LSM) is applied to the long LWs. Experimental results prove that relatively constant results
with various training data can be obtained from a MM. The Transformation-Based Error Driven Learning (TBED) algorithm, for
its high performance of individual property, is applied in combination with the MM to improve the precision of PW segmentation.
Experiments show that among the three proposed models, the MM combined with TBED and LSM, leads to the best performance, in
which a precision of 93.00% and a recall of 93.23% are achieved. The perception test indicates that by using PWs as the lowest
prosodic units a speech sounds more natural and acceptable than by using LWs.
This paper is supported by NSFC Project (60503071); 973 Natural Basic Research Program of China (2004CB318102); Postdoctor
Science Foundation of P. R. China (20070420275). 相似文献