全文获取类型
收费全文 | 3500篇 |
免费 | 236篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 19篇 |
综合类 | 6篇 |
化学工业 | 951篇 |
金属工艺 | 39篇 |
机械仪表 | 51篇 |
建筑科学 | 206篇 |
矿业工程 | 3篇 |
能源动力 | 56篇 |
轻工业 | 591篇 |
水利工程 | 37篇 |
石油天然气 | 18篇 |
无线电 | 142篇 |
一般工业技术 | 519篇 |
冶金工业 | 634篇 |
原子能技术 | 9篇 |
自动化技术 | 458篇 |
出版年
2023年 | 26篇 |
2022年 | 86篇 |
2021年 | 131篇 |
2020年 | 56篇 |
2019年 | 88篇 |
2018年 | 97篇 |
2017年 | 84篇 |
2016年 | 115篇 |
2015年 | 85篇 |
2014年 | 154篇 |
2013年 | 222篇 |
2012年 | 185篇 |
2011年 | 267篇 |
2010年 | 179篇 |
2009年 | 153篇 |
2008年 | 184篇 |
2007年 | 154篇 |
2006年 | 168篇 |
2005年 | 105篇 |
2004年 | 122篇 |
2003年 | 100篇 |
2002年 | 84篇 |
2001年 | 57篇 |
2000年 | 57篇 |
1999年 | 50篇 |
1998年 | 49篇 |
1997年 | 48篇 |
1996年 | 52篇 |
1995年 | 43篇 |
1994年 | 38篇 |
1993年 | 34篇 |
1992年 | 40篇 |
1991年 | 37篇 |
1990年 | 47篇 |
1989年 | 32篇 |
1988年 | 35篇 |
1987年 | 29篇 |
1986年 | 22篇 |
1985年 | 22篇 |
1984年 | 31篇 |
1983年 | 12篇 |
1982年 | 24篇 |
1980年 | 15篇 |
1979年 | 24篇 |
1978年 | 14篇 |
1977年 | 8篇 |
1975年 | 13篇 |
1974年 | 6篇 |
1971年 | 6篇 |
1969年 | 6篇 |
排序方式: 共有3739条查询结果,搜索用时 15 毫秒
91.
Jørgensen MB Faber A Jespersen T Hansen K Ektor-Andersen J Hansen JV Holtermann A Søgaard K 《Ergonomics》2012,55(7):762-772
This study evaluates the implementation of physical coordination training (PCT) and cognitive behavioural training (CBTr) interventions in a randomised controlled trial at nine cleaners' workplaces. Female cleaners (n = 294) were randomised into a PCT, a CBTr or a reference (REF) group. Both 12-week interventions were performed in groups guided by an instructor. Records were kept on intervention dose (adherence) unanticipated events at the work place (context) and quality of intervention delivery (fidelity). Participant adherence was 37% in the PCT and 49% in the CBTr interventions. Optimal implementation was reached by only 6% in PCT and 42% in the CBTr. Analysis of the barriers to successful implementation indicated that the intervention process is sensitive to unanticipated events. In order to succeed in improving the health of high-risk populations such as cleaners and to correctly interpret intervention effects, more research on implementation is needed. Trial registration: ISRCTN96241850. PRACTITIONER SUMMARY: Both physical coordination training and cognitive behavioural training are potential effective workplace interventions among low educated job groups with high physical work demands. However, thorough consideration should be given to feasibility in the design of interventions. The optimal intervention should be tailored to closely match the implementation context and be robust and flexible to minimise susceptibility to changes in work organisation. 相似文献
92.
Liu Grace T.; Ferguson Adam R.; Crown Eric D.; Bopp Anne C.; Miranda Rajesh C.; Grau James W. 《Canadian Metallurgical Quarterly》2005,119(2):538
Following spinal transection of the upper thoracic spinal cord, male Sprague-Dawley rats given legshock whenever a hindlimb is extended learn to maintain the leg in a flexed position. The region of the cord that mediates this instrumental learning was isolated using neuroanatomical tracing, localized infusion of lidocaine, and surgical transections. DiI and Fluoro-Gold microinjection at the site of shock application labeled motor neuron bodies of lamina IX in the lower lumbar region. Local application of the Na++ channel blocker lidocaine disrupted learning when it was applied over a region extending from the lower lumbar (L3) to upper sacral (S2) cord. The drug had no effect rostral or caudal to this region. Surgical transections as low as L4 had no effect on learning. Learning also survived a dual transection at L4 and S3, but not L4 and S2. The results suggest that the essential neural circuit lies between L4 and S3. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
93.
Nicole Altvater-Mackensen Gregor Balicki Lucie Bestakowa Bianca Bocatius Johannes Braun Lars Brehmer Verena Brune Kirstina Eigemeier F&#;sun Erdem Ralf Fritscher Anne Jacobs Bernd Klingsporn Marcin Kosinski Julia Kuntze Ju-Ra Lee Anna Osterhage Martin Probost Thorsten Risch Tobias Schmitt Wolfgang G. Stock Anja Sturm Katrin Weller Kerstin Werner 《Scientometrics》2005,63(3):463-529
Summary We operationalize scientific output in a region by means of the number of articles (as in the SciSearch database) per year and technology output by means of the number of patent applications (as in the database of the European Patent Office) per priority year. All informetric analyses were done using the DIALOG online-system. The main research questions are the following: Which scientific and technological fields or topics are most influent within a region and which institutions or companies are mainly publishing articles or holding patents? Do the distributions of regional science and technology fields and of publishing institutions follow the well-known informetric function? Are there - as it is expected - only few fields and few institutions which dominate the region? Is there a connection between the economic power of a region and the regional publication and patent output? Examples studied in detail are seven German regions: Aachen, Düsseldorf, Hamburg, Köln (Cologne), Leipzig - Halle - Dessau, München (Munich), and Stuttgart. Three different indicators were used, science and technology attraction of a region (number of scientific articles and patents), science and technology intensity (articles and patents per 1,000 inhabitants), and science and technology density (articles and patents per 1 billion EURO gross value added). Top region concerning both attraction and intensity is Munich, concerning density it is Aachen. 相似文献
94.
Andronescu Mirela Dees Danielle Slaybaugh Laura Zhao Yinglei Condon Anne Cohen Barry Skiena Steven 《Natural computing》2003,2(4):391-415
We present an efficient algorithm for determining whether all moleculesin a combinatorial set of DNA or RNA strandsare structure free, and thus availablefor bonding to their Watson-Crick
complements.This work is motivated by the goalof testing whether strands used in DNAcomputations or as molecular bar-codesare
structure free, where the strands areconcatenations of short words. We alsopresent an algorithm for determining whetherall
words in S*, for some finite setS of equi-length words, are structure free.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
95.
This article provides an overview of the factors that may contribute to the effective term of protection for a pharmaceutical product in the USA––by patent and by FDA market exclusivities, identifies public and commercial sources for collecting relevant patent term and exclusivity data, and provides a strategy for ensuring that the effective term of protection has been calculated accurately. 相似文献
96.
E. J. O'Brien, M. L. Rizzella, J. E. Albrecht, and J. G. Halleran (1998) demonstrated that, consistent with the memory-based text processing view, outdated or incorrect information can be reactivated through a passive resonance process. Once reactivated, this outdated information can still influence comprehension. R. A. Zwaan and C. J. Madden (2004) suggested that the O'Brien et al. findings resulted from problems with the materials used. The present authors show that the possible "problems" identified by Zwaan and Madden do not adequately explain the findings of O'Brien et al. and that Zwaan and Madden's Experiment 3 lacks sufficient control or power to support their alternative interpretation of O'Brien et al. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
97.
Zachary Finewax Demetrios Pagonis Megan S. Claflin Anne V. Handschy Wyatt L. Brown Olivia Jenks Benjamin A. Nault Douglas A. Day Brian M. Lerner Jose L. Jimenez Paul J. Ziemann Joost A. de Gouw 《Indoor air》2021,31(5):1323-1339
Humans spend approximately 90% of their time indoors, impacting their own air quality through occupancy and activities. Human VOC emissions indoors from exercise are still relatively uncertain, and questions remain about emissions from chlorine-based cleaners. To investigate these and other issues, the ATHLETic center study of Indoor Chemistry (ATHLETIC) campaign was conducted in the weight room of the Dal Ward Athletic Center at the University of Colorado Boulder. Using a Vocus Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (Vocus PTR-TOF), an Aerodyne Gas Chromatograph (GC), an Iodide-Chemical Ionization Time-of-Flight Mass Spectrometer (I-CIMS), and Picarro cavity ringdown spectrometers, we alternated measurements between the weight room and supply air, allowing for determination of VOC, NH3, H2O, and CO2 emission rates per person (emission factors). Human-derived emission factors were higher than previous studies of measuring indoor air quality in rooms with individuals at rest and correlated with increased CO2 emission factors. Emission factors from personal care products (PCPs) were consistent with previous studies and typically decreased throughout the day. In addition, N-chloraldimines were observed in the gas phase after the exercise equipment was cleaned with a dichlor solution. The chloraldimines likely originated from reactions of free amino acids with HOCl on gym surfaces. 相似文献
98.
99.
100.
Anne Hammond 《History of Photography》2013,37(4):388-391
Abstract In 1963, Clark Kerr, then President of the University of California, approached Ansel Adams and Nancy Newhall to participate in the centennial celebrations (in 1968) of the founding of the University. Adams's photographic work on the nme campuses in the years following resulted in the production of six thousand negatives, from which six hundred and five were produced as fine prints (placed in the University Archives at the Bancroft Library at Berkeley) and many others reproduced in the book, Fiat Lux (1968), with text by Nancy Newhall. In 1990, an exhibition consisting of one hundred of those photographs (to celebrate the twenty-fifth anniversary of the University of California at Irvine) toured the campuses of the University between January 1991 and May 1992, accompanied by the exhibition catalogue, Ansel Adams: Fiat Lux. 相似文献