全文获取类型
收费全文 | 341581篇 |
免费 | 34244篇 |
国内免费 | 25553篇 |
专业分类
电工技术 | 44325篇 |
技术理论 | 30篇 |
综合类 | 40732篇 |
化学工业 | 21251篇 |
金属工艺 | 11576篇 |
机械仪表 | 27240篇 |
建筑科学 | 30750篇 |
矿业工程 | 13091篇 |
能源动力 | 13850篇 |
轻工业 | 8887篇 |
水利工程 | 14482篇 |
石油天然气 | 13526篇 |
武器工业 | 5530篇 |
无线电 | 31825篇 |
一般工业技术 | 22700篇 |
冶金工业 | 11303篇 |
原子能技术 | 3531篇 |
自动化技术 | 86749篇 |
出版年
2024年 | 1416篇 |
2023年 | 3913篇 |
2022年 | 7718篇 |
2021年 | 9294篇 |
2020年 | 10021篇 |
2019年 | 7930篇 |
2018年 | 7449篇 |
2017年 | 9883篇 |
2016年 | 11555篇 |
2015年 | 12831篇 |
2014年 | 21242篇 |
2013年 | 19696篇 |
2012年 | 25105篇 |
2011年 | 26821篇 |
2010年 | 20596篇 |
2009年 | 20922篇 |
2008年 | 21270篇 |
2007年 | 25964篇 |
2006年 | 23077篇 |
2005年 | 20486篇 |
2004年 | 16724篇 |
2003年 | 14941篇 |
2002年 | 11497篇 |
2001年 | 9619篇 |
2000年 | 8057篇 |
1999年 | 6415篇 |
1998年 | 5031篇 |
1997年 | 4082篇 |
1996年 | 3697篇 |
1995年 | 3150篇 |
1994年 | 2613篇 |
1993年 | 1784篇 |
1992年 | 1514篇 |
1991年 | 1129篇 |
1990年 | 901篇 |
1989年 | 751篇 |
1988年 | 507篇 |
1987年 | 309篇 |
1986年 | 207篇 |
1985年 | 212篇 |
1984年 | 202篇 |
1983年 | 135篇 |
1982年 | 133篇 |
1981年 | 96篇 |
1980年 | 97篇 |
1979年 | 90篇 |
1978年 | 48篇 |
1977年 | 34篇 |
1976年 | 26篇 |
1959年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
Hui-Chih Wang 《Behaviour & Information Technology》2014,33(10):1082-1092
For decades, the marketing guidelines of enterprise software providers have focused on those managers who are likely to be more innovative in adopting new information systems. The current study argues that this approach demands improvements for two reasons: (1) this tactic may be biased, since past studies have only examined the single trait of innovativeness and its impact on an individual adoption intention and (2) the organisational implementation intention might be more important than the individual adoption intention, but the former has been largely ignored in the existing literature. Based on the case of business intelligence (BI) systems and data from 62 senior managers, this study is a pioneer in that it empirically reveals that managers’ individual adoption intention is distinct from their organisational implementation intention. Further, while managers’ innovativeness may be a significant determinant of their individual adoption intention towards BI systems, the issue of whether managers actually implement BI systems in their organisations is dominated by their involvement characteristics. Fruitful suggestions are proposed for practitioners and scholars. 相似文献
142.
Philip K Gbor 《Chemical engineering science》2004,59(10):1979-1987
The shrinking core model (SCM) is widely used to model fluid-solid reactions such as the leaching of metals from minerals. In most cases, however, the particle size distribution (PSD) of the solid material was disregarded. In this paper the erroneous shift in the control regime when neglecting PSD was quantified and the dependence of the shift on the coefficients of variation (CV) and the type of PSD was analysed. By coupling the SCM with a Gamma PSD, it was found that neglecting the PSD would shift the control regime from chemical reaction to inert/ash layer diffusion, when the CV was between 0.7 and 1.2. For a system controlled by liquid film diffusion, neglect of the PSD, would shift the control regime to chemical reaction when CV is between 0.3 and 0.7 or to inert/ash layer diffusion when CV is greater (0.9-1.5). It was therefore postulated that some researchers had unknowingly made invalid conclusions about the control regime due to the neglect of PSD. However, an inert/ash layer diffusion-controlled process was insensitive to the neglect of PSD. When CV<0.3, neglect of the PSD would not cause any erroneous shifts, irrespective of the control regime. Experimental data confirmed the observation. For a given CV, the deviation in the fraction reacted from the mono-PSD increases with CV and decreases with time. The maximum deviation, which occurs at the beginning, is about 10% with a gamma PSD of CV=0.3. The percent deviation is dependent of the type of PSDs. Gamma PSD gives the lowest deviation while Gaudin-Schuhmann results in the largest deviation (maxi. ∼19%, with CV=0.3) in the first half of dissolution process. Log-normal distribution gives a larger deviation than gamma but quickly approaches the latter with time. The deviation for Rosin-Rammler is between log-normal and Gaudin-Schuhmann. For systems with CV less than 0.3, the SCM can be fairly used without considering PSD. When CV is greater than 0.3, particularly in the early stage of a dissolution process with a PSD other than gamma, PSD should be included to avoid substantial errors. 相似文献
143.
144.
近年来,高职院校都比较注重特色专业的建设。其中,特色专业建设的监控体系也受到了高职院校的重视,并取得了一定的效果,同时,也给其他院校提供了有价值的参考和借鉴。但由于在认识水平、管理水平和教学水平等方面仍有一些问题,导致在监控过程和措施实施方面还存在许多疏漏,有待完善。 相似文献
145.
物联网技术作为一项新兴的技术,已经成为了研究人员研究的热点。智能家居作为物联网的一个重要的分支,几年来发展迅猛,为人们提供了理想的家居环境。人们追求更加理想的生活环境,为了满足人们的追求,我们设计了一款基于zigbee技术的智能化窗帘。该系统是基于zigbee技术的的一款可以无线通信的智能化窗帘。采用的是TI公司的cc2530的zigbee片上应用系统。通过无线传输技术、传感技术等实现窗帘的智能控制。 相似文献
146.
为了使传统的审核过程信息化、数字化,对硕士学位授权点审核系统将要实现的管理功能进行分析,并介绍了开发技术和发布平台的设计,以及在建设过程中要解决的关键性问题。该系统开发之后,已在本省上线并运行,效果良好。希望该系统的设计、实现和实际运行能够为其他兄弟省份提供借签。 相似文献
147.
线性动态系统模型结合稀疏编码实现异常事件检测。线性动态系统可有效地捕捉动态纹理在时间和空间的转移信息,描述视频的时空小块。然而,线性动态系统属于非欧氏空间,无法直接用传统的稀疏编码进行异常检测。基于约束凸优化公式,将相似性变换与稀疏编码结合,可实现线性动态系统稀疏编码的优化求解。实验表明,所提出的方法具有更好的性能。 相似文献
148.
本文设计并实现了基于J2EE的高校教师业务管理系统.文章详细讨论了系统实现的业务模型、功能模型等需求分析过程,以及系统架构、通用查询框架、基于角色访问控制策略的“用户一角色.功能模块”的权限管理系统设计与实现等关键技术. 相似文献
149.
150.
The use of colorimetry within industry has grown extensively in the last few decades. Central to many of today's instruments is the CIE system, established in 1931. Many have questioned the validity of the assumptions made by Wright1 and Guild,2 some suggesting that the 1931 color‐matching functions are not the best representation of the human visual system's cone responses. A computational analysis was performed using metameric data to evaluate the CIE 1931 color‐matching functions as compared to with other responsivity functions. The underlying assumption was that an optimal set of responsivity functions would yield minimal color‐difference error between pairs of visually matched metamers. The difference of average color differences found in the six chosen sets of responsivity functions was small. The CIE 1931 2° color‐matching functions on average yielded the largest color difference, 4.56 ΔE. The best performance came from the CIE 1964 10° color‐matching functions, which yielded an average color difference of 4.02 ΔE. An optimization was then performed to derive a new set of color‐matching functions that were visually matched using metameric pairs of spectral data. If all pairs were to be optimized to globally minimize the average color difference, it is expected that this would produce an optimal set of responsivity functions. The optimum solution was to use a weighted combination of each set of responsivity functions. The optimized set, called the Shaw and Fairchild responsivity functions, was able to reduce the average color difference to 3.92 ΔE. In the final part of this study a computer‐based simulation of the color differences between the sets of responsivity functions was built. This simulation allowed a user to load a spectral radiance or a spectral reflectance data file and display the tristimulus match predicted by each of the seven sets of responsivity functions. © 2002 Wiley Periodicals, Inc. Col Res Appl, 27, 316–329, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10077 相似文献