全文获取类型
收费全文 | 1475篇 |
免费 | 24篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 9篇 |
综合类 | 7篇 |
化学工业 | 237篇 |
金属工艺 | 282篇 |
机械仪表 | 26篇 |
建筑科学 | 30篇 |
矿业工程 | 9篇 |
能源动力 | 12篇 |
轻工业 | 201篇 |
水利工程 | 8篇 |
石油天然气 | 5篇 |
无线电 | 45篇 |
一般工业技术 | 175篇 |
冶金工业 | 150篇 |
原子能技术 | 1篇 |
自动化技术 | 305篇 |
出版年
2023年 | 7篇 |
2022年 | 6篇 |
2021年 | 14篇 |
2020年 | 5篇 |
2019年 | 10篇 |
2018年 | 77篇 |
2017年 | 74篇 |
2016年 | 78篇 |
2015年 | 83篇 |
2014年 | 33篇 |
2013年 | 47篇 |
2012年 | 52篇 |
2011年 | 628篇 |
2010年 | 47篇 |
2009年 | 39篇 |
2008年 | 46篇 |
2007年 | 25篇 |
2006年 | 18篇 |
2005年 | 17篇 |
2004年 | 17篇 |
2003年 | 16篇 |
2002年 | 11篇 |
2001年 | 3篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 10篇 |
1997年 | 10篇 |
1996年 | 4篇 |
1995年 | 9篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 9篇 |
1990年 | 9篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 6篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1971年 | 2篇 |
排序方式: 共有1502条查询结果,搜索用时 245 毫秒
1.
2.
3.
4.
Wilcox Sara; Evenson Kelly R.; Aragaki Aaron; Wassertheil-Smoller Sylvia; Mouton Charles P.; Loevinger Barbara Lee 《Canadian Metallurgical Quarterly》2003,22(5):513
This study examined whether widowhood was associated with physical and mental health, health behaviors, and health outcomes using a cross-sectional (N=72,247) and prospective (N=55,724) design in women aged 50-79 years participating in the Women's Health Initiative observational study (85.4% White). At baseline, married women reported better physical and mental health and generally better health behaviors than widowed women. Whereas women who remained married over the 3-year period showed stability in mental health, recent widows experienced marked impairments and longer term widows showed stability or slight improvements. Both groups of widows reported more unintentional weight loss over the 3-year period. Changes in physical health and health behaviors were inconsistent, with generally small effect sizes. Findings underscore the resilience of older women and their capacity to reestablish connections, but point to the need for services that strengthen social support among women who have difficulty during this transition. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
Berninger Virginia W.; Vaughan Katherine; Abbott Robert D.; Brooks Allison; Abbott Sylvia P.; Rogan Laura; Reed Elizabeth; Graham Steve 《Canadian Metallurgical Quarterly》1998,90(4):587
Poor spellers in 2nd grade (n?=?128) participated in 24 20-min sessions that included (a) direct instruction in the alphabet principle (most frequent phoneme-spelling connections); (b) modeling of different approaches, singly and in combination, for developing connections between spoken and written words for 48 words ordered by sound-spelling predictability; and (c) practice in composing. Results of this multilayered intervention showed that (a) more than 1 way of developing sound-spelling connections is effective in teaching spelling but that after training in the alphabet principle, combining whole word and onset-rime training is most effective in achieving transfer of the alphabet principle across word contexts; (b) functional spelling units of not only a single letter but also 2 or more letters are important in beginning spelling; and (c) training in spelling transfers to composition and word recognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
6.
Conclusion Because of the success of this project as measured by the favorable comments of the participants as well as the increased
search activity, the Council on the Humanities awarded an additional $1000 to continue the project in the spring of 1985.
As an added feature of the new proposal, a workshop is planned for chairs of the various humanities departments as well as
other interested humanists. The aim will be to encourage them and their colleagues to increase their involvement in automated
literature searching, as well as to encourage their graduate students to use the service. With continued support, greater
awareness of the service, and more extensive coverage of existing and future databases,3 a steady increase in computer-assisted bibliographic searching among humanists is definitely possible. 相似文献
7.
Sylvia V A Uzochukwu Esther Balogh Owen G Tucknot Mervyn J Lewis Patrick O Ngoddy 《Journal of the science of food and agriculture》1994,64(4):405-411
Palm wine and pasteurised palm sap volatiles were collected, concentrated on a Tenax GC and analysed by gas chromatography and gas chromatography-mass spectrometry. Eighty-two components were identified: 47 esters, 9 alcohols, 5 acids, 6 carbonyls, 2 acetals, 4 terpenes and 9 hydrocarbons. These had all been found previously in conventional wines. Odour evaluation of the separated palm wine components as they eluted suggested that no one compound is responsible for the characteristic palm wine odour. The acetates of higher alcohols and the ethyl esters of straight-chain aliphatic C6-C10 acids seemed to be important and may play a big role in imparting the fruity nuances of characteristic palm wine odour. Their association with alcohols seemed also to be necessary for the expression of typical palm wine odour. The qualitative difference between palm sap aroma and palm wine aroma appeared to be due mainly to the presence of these esters and alcohols in palm wine and their apparent absence from palm sap, as well as to the presence of some low-boiling esters and alcohols in palm sap and their apparent absence from palm wine. 相似文献
8.
A. Alp Kindiroglu H. Yalcin O. Aran M. Hr��z P. Campr L. Akarun A. Karpov 《Pattern Recognition and Image Analysis》2012,22(4):527-536
This paper presents the design and evaluation of a multi-lingual fingerspelling recognition module that is designed for an information terminal. Through the use of multimodal input and output methods, the information terminal acts as a communication medium between deaf and blind people. The system converts fingerspelled words to speech and vice versa using fingerspelling recognition, fingerspelling synthesis, speech recognition and speech synthesis in Czech, Russian, and Turkish languages. We describe an adaptive skin color based fingersign recognition system with a close to real-time performance and present recognition results on 88 different letters signed by five different signers, using above four hours of training and test videos. 相似文献
9.
Magnetic particles diluted in liquid agglomerate in rod-like particle arrays if an external homogeneous magnetic field is
applied. This work introduces a method to specifically exploit particle–particle interaction to obtain flow control of magnetic
particles without changing the motion state of the carrier liquid. Experiments show the possibility to uncouple the particle
flux from the motion state of liquid. We show how this method may be applied to design a microfluidic geometry in which the
particle flow in a specific direction is either enabled or suppressed by the relative orientation of the fluid velocity and
the external field. 相似文献
10.
Marc Karle Johannes W?hrle Junichi Miwa Nils Paust G��nter Roth Roland Zengerle Felix von Stetten 《Microfluidics and nanofluidics》2011,10(4):935-939
We demonstrate controlled transport of superparamagnetic beads in the opposite direction of a laminar flow. A permanent magnet
assembles 200 nm magnetic particles into about 200 μm long bead chains that are aligned in parallel to the magnetic field
lines. Due to a magnetic field gradient, the bead chains are attracted towards the wall of a microfluidic channel. A rotation
of the permanent magnet results in a rotation of the bead chains in the opposite direction to the magnet. Due to friction
on the surface, the bead chains roll along the channel wall, even in counter-flow direction, up to at a maximum counter-flow
velocity of 8 mm s−1. Based on this approach, magnetic beads can be accurately manoeuvred within microfluidic channels. This counter-flow motion
can be efficiently be used in Lab-on-a-Chip systems, e.g. for implementing washing steps in DNA purification. 相似文献