全文获取类型
收费全文 | 37072篇 |
免费 | 4060篇 |
国内免费 | 2585篇 |
专业分类
电工技术 | 1766篇 |
技术理论 | 5篇 |
综合类 | 2825篇 |
化学工业 | 1583篇 |
金属工艺 | 1294篇 |
机械仪表 | 3976篇 |
建筑科学 | 1392篇 |
矿业工程 | 551篇 |
能源动力 | 636篇 |
轻工业 | 890篇 |
水利工程 | 535篇 |
石油天然气 | 670篇 |
武器工业 | 367篇 |
无线电 | 5068篇 |
一般工业技术 | 3795篇 |
冶金工业 | 1112篇 |
原子能技术 | 529篇 |
自动化技术 | 16723篇 |
出版年
2024年 | 126篇 |
2023年 | 502篇 |
2022年 | 879篇 |
2021年 | 957篇 |
2020年 | 1015篇 |
2019年 | 808篇 |
2018年 | 843篇 |
2017年 | 1197篇 |
2016年 | 1362篇 |
2015年 | 1474篇 |
2014年 | 2278篇 |
2013年 | 2168篇 |
2012年 | 2386篇 |
2011年 | 3018篇 |
2010年 | 2141篇 |
2009年 | 2110篇 |
2008年 | 2192篇 |
2007年 | 2470篇 |
2006年 | 2095篇 |
2005年 | 1765篇 |
2004年 | 1563篇 |
2003年 | 1533篇 |
2002年 | 1224篇 |
2001年 | 1002篇 |
2000年 | 919篇 |
1999年 | 863篇 |
1998年 | 899篇 |
1997年 | 691篇 |
1996年 | 574篇 |
1995年 | 460篇 |
1994年 | 359篇 |
1993年 | 315篇 |
1992年 | 272篇 |
1991年 | 208篇 |
1990年 | 171篇 |
1989年 | 127篇 |
1988年 | 150篇 |
1987年 | 60篇 |
1986年 | 86篇 |
1985年 | 108篇 |
1984年 | 82篇 |
1983年 | 57篇 |
1982年 | 32篇 |
1981年 | 32篇 |
1980年 | 15篇 |
1979年 | 20篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1974年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
141.
A. E. Isaev 《Measurement Techniques》2007,50(8):888-893
Methods of reducing the predominant components of uncertainty in standards of sound pressure in an aqueous medium in a free
field, and also methods of increasing the accuracy when the dimensions of the unit of a physical quantity are transferred
by the means employed in natural measurements are reviewed.
__________
Translated from Izmeritel’naya Tekhnika, No. 8, pp. 59–63, August, 2007. 相似文献
142.
143.
从含钴催化剂废料中回收氧化钴的研究 总被引:1,自引:0,他引:1
选用酸溶——沉淀化学法,对含钴催化剂废料提取氧化钴的实验研究。实验结果表明,回收氧化钴产品中含钴量71%,氧化钴的实收率85%。同时将铁回收为铁红产品(含Fe2O3≤65%),铁的实收率高达88%。其它的技术经济指标较高。这是一种工艺技术及设备可行的新途径。 相似文献
144.
Stephen Dain 《Color research and application》2007,32(6):428-432
There are anecdotal reports of color vision deficient medical practitioners (particularly deuteranopes) having difficulty in recognizing cyanosis. An understanding of the color changes in oxygenated blood has led to a better understanding of the lighting needs for hospitals. Using the same database, this article investigates the propensity for color vision deficient observers to make mistakes with cyanotic patients. The possibilities for helping the observer with appropriate color of lighting are considered. The spectral reflectances of blood at varying oxygenation levels previously reported were used 7 ; 8 to calculate chromaticity and lightness. The direction of the chromaticity change was compared with the protanopic and deuteranopic confusion lines. An attempt was made to identify sources that enhanced color changes for the color deficient. The color change of blood oxygenation is closely aligned with the confusion lines of congenital dichromats (particularly protanopia) showing the potential for difficulty in making this decision. No source could be demonstrated to solve the problem or even reduce it significantly. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 428–432, 2007 相似文献
145.
Diana Hurdowar-Castro Ioannis Tsanis Ilmar Simanovskis 《Journal of Great Lakes research》2007,33(1):232-252
A 3D transport model is used to perform a comparative analysis of several potential drinking water intakes located along the northwest shore of Lake Ontario between Toronto and Oshawa. The model is specifically used to assess each intake under both long- and short-term transport of a potential pollutant release from the Pickering Nuclear Generating Station and potential and actual pollutant releases from local land sources respectively. A model based on a 500 m grid resolution is calibrated using data collected in the aftermath of the 1992 tritium spill at the Pickering Nuclear Generation Station and subsequently used to simulate long-term transport. A model based on a 100 m grid resolution is verified using drogue studies and used to simulate short-term transport events. Both models are used to assess pollutant levels at each of nine potential intake locations under different wind scenarios and pollutant releases. Field data for the study included water quality and flow measurements from local sewers and rivers, and estimates of pollutant levels from the local waste water treatment plants. This paper describes the model setup for both the long-term and short-term transport models, calibration using field data, long-term transport modeling, short-term transport modeling, and the comprehensive analysis approach used to evaluate the nine potential intake locations proposed. Results indicated that four intakes in particular outperformed other intake locations by maintaining bottom pollutant levels within governmental standards and warning times that exceeded 20 hours. 相似文献
146.
Ralph W. Pridmore 《Color research and application》2007,32(3):208-222
A color stimulus may be characterized by three psychophysical dimensions (luminance, dominant wavelength, and purity), whose corresponding color attributes are lightness, hue, and chroma/colorfulness. The 3 × 3 matrix gives nine basic effects of the psychophysical dimensions on the color attributes (e.g. the effect of luminance on hue), but there are 49 possible combinations as more complex effects (e.g. the effect of luminance on hue and chroma, i.e. on chromaticity). Researching and quantifying such effects enables modelling of the underlying neural mechanisms and of color appearance. Using a simple nomenclature to identify the effects (e.g. Ph denotes the effect of Purity on hue), this paper briefly reviews and interrelates 15 of the commonest effects, giving new data or new graphical perspectives to clarify or fill gaps in the literature. Contrast and no‐contrast effects (stimuli viewed simultaneously or singly, respectively) are differentiated. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 208–222, 2007 相似文献
147.
We introduce an effective computer aided learning visual tool (CALVT) to teach graph-based applications. We present the robot motion planning problem as an example of such applications. The proposed tool can be used to simulate and/or further to implement practical systems in different areas of computer science such as graphics, computational geometry, robotics and networking. In the robot motion planning example, CALVT enables users to setup the working environment by creating obstacles and a robot of different shapes, specifying starting and goal positions, and setting other path or environment parameters from a user-friendly interface. The path planning system involves several phases. Each of these modules is complex and therefore we provide the possibility of visualizing graphically the output of each phase. Based on our experience, this tool has been an effective one in classroom teaching. It not only cuts down, significantly, on the instructor’s time and effort but also motivates senior/graduate students to pursue work in this specific area of research. 相似文献
148.
149.
150.
本文首先概述了编辑出版自动化技术的概念及最新进展,然后就其在医药专业期刊编辑部的初步应用进行了探讨,论述了计算机、网络、数据库技术在稿件的选题、组稿、编辑、审校、排版、印刷、出版中的具体应用,强调了构建基于网络的编辑出版自动化系统对期刊现代化建设的重要作用。 相似文献