全文获取类型
收费全文 | 4271篇 |
免费 | 187篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 36篇 |
综合类 | 6篇 |
化学工业 | 945篇 |
金属工艺 | 41篇 |
机械仪表 | 77篇 |
建筑科学 | 355篇 |
矿业工程 | 12篇 |
能源动力 | 125篇 |
轻工业 | 465篇 |
水利工程 | 45篇 |
石油天然气 | 11篇 |
武器工业 | 1篇 |
无线电 | 284篇 |
一般工业技术 | 660篇 |
冶金工业 | 530篇 |
原子能技术 | 21篇 |
自动化技术 | 846篇 |
出版年
2023年 | 28篇 |
2022年 | 38篇 |
2021年 | 64篇 |
2020年 | 52篇 |
2019年 | 75篇 |
2018年 | 91篇 |
2017年 | 88篇 |
2016年 | 108篇 |
2015年 | 73篇 |
2014年 | 141篇 |
2013年 | 317篇 |
2012年 | 189篇 |
2011年 | 286篇 |
2010年 | 210篇 |
2009年 | 212篇 |
2008年 | 220篇 |
2007年 | 233篇 |
2006年 | 178篇 |
2005年 | 173篇 |
2004年 | 128篇 |
2003年 | 103篇 |
2002年 | 117篇 |
2001年 | 64篇 |
2000年 | 78篇 |
1999年 | 79篇 |
1998年 | 92篇 |
1997年 | 81篇 |
1996年 | 92篇 |
1995年 | 58篇 |
1994年 | 50篇 |
1993年 | 51篇 |
1992年 | 50篇 |
1991年 | 33篇 |
1990年 | 34篇 |
1989年 | 40篇 |
1988年 | 33篇 |
1987年 | 36篇 |
1986年 | 35篇 |
1985年 | 37篇 |
1984年 | 56篇 |
1983年 | 44篇 |
1982年 | 38篇 |
1981年 | 33篇 |
1980年 | 33篇 |
1979年 | 22篇 |
1978年 | 28篇 |
1977年 | 22篇 |
1976年 | 29篇 |
1975年 | 26篇 |
1973年 | 13篇 |
排序方式: 共有4460条查询结果,搜索用时 15 毫秒
141.
Careful selection of steaming and attrition conditions during thermo‐mechanical pretreatment can increase enzymatic conversion of softwood
下载免费PDF全文
![点击此处可从《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
142.
143.
Yuechen Qiao My Yang Ian A. Marabella Devin A.J. McGee Bernard A. Olson Montserrat Torremorell Christopher J. Hogan Jr. 《Indoor air》2021,31(6):2058-2069
Recirculating air purification technologies are employed as potential means of reducing exposure to aerosol particles and airborne viruses. Toward improved testing of recirculating air purification units, we developed and applied a medium-scale single-pass wind tunnel test to examine the size-dependent collection of particles and the collection and inactivation of viable bovine coronavirus (BCoV, a betacoronavirus), porcine respiratory coronavirus (PRCV, an alphacoronavirus), and influenza A virus (IAV), by a commercial air purification unit. The tested unit, the Molekule Air Mini, incorporates a MERV 16 filter as well as a photoelectrochemical oxidating layer. It was found to have a collection efficiency above 95.8% for all tested particle diameters and flow rates, with collection efficiencies above 99% for supermicrometer particles with the minimum collection efficiency for particles smaller than 100 nm. For all three tested viruses, the physical tracer-based log reduction was near 2.0 (99% removal). Conversely, the viable virus log reductions were found to be near 4.0 for IAV, 3.0 for BCoV, and 2.5 for PRCV, suggesting additional inactivation in a virus family- and genus-specific manner. In total, this work describes a suite of test methods which can be used to rigorously evaluate the efficacy of recirculating air purification technologies. 相似文献
144.
Negative‐imaginary systems are important in engineering practice as this class of systems appears quite often in practical problems, for example, lightly damped flexible structures with collocated position sensors and force actuators. In this paper, an analytical framework for robust performance of uncertain negative‐imaginary systems is proposed. The results are obtained by transforming negative‐imaginary systems into a bounded‐real framework via the positive‐real property. This paper deals with all the significant technical difficulties that appear due to the transformation and the punctured j ω‐axis frequency condition of negative‐imaginary systems. The problem is equivalently cast into a structured singular value condition that gives a quantitative performance test for this class of systems. This result also gives an analytical framework for robust stability when the perturbations are mixture of bounded‐real and negative‐imaginary uncertainties. A numerical example is presented to show the usefulness of the proposed methods. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
145.
Rudra P. Bhatta Mark Henderson Andreza Eufrasio Ian L. Pegg Biprodas Dutta 《Journal of Electronic Materials》2014,43(11):4056-4063
In thermopower measurements, microwires fabricated from as-purchased bulk PbTe exhibits p-type behavior between room temperature and ~600 K. At higher temperatures, it undergoes majority carrier inversion and exhibits n-type behavior. We report on the preparation and properties of potassium oxide and Zn-doped PbTe microwires, which exhibit stable p- and n-type behavior, respectively, between room temperature and 725 K. Thermoelectric figures of merit (ZT) are reported for device components prepared from bundles of such p- and n-type microwires in a glass matrix. 相似文献
146.
Bo Chen Teruo Hashimoto Frank Vergeer Andrew Burgess George Thompson Ian Robinson 《Progress in Organic Coatings》2014
The three-dimensional (3D) spatial structure of an iron oxide containing alkyd paint specimen has been investigated by serial block-face scanning electron microscopy (SBFSEM). The resultant images of the 3D structure clearly present the spatial distribution of the iron oxide pigment particles in the coating film and reveal the extent of aggregation of the particles in the matrix material. More than one-half of the iron oxide particles (in volume) had aggregated to form clusters of considerable sizes that follow a Gaussian spacing distribution in the measured coating film. Over 80% of the clusters have dimensions between 1.5 μm and 3.5 μm; also, pores are evident at the centres of clusters whose sizes are larger than 2 μm. The work demonstrated here reveals a new approach to fully characterize the 3D spatial structure of coatings and to explore their correlations with the performance of the materials. 相似文献
147.
148.
This paper provides an introduction and an editorial to this special issue of River Research and Applications by documenting the contributions made by Professor Geoffrey Petts to our interdisciplinary understanding of the functioning of rivers and their floodplains and their sustainable management. We outline Geoff's career, which framed not only his research but its communication through his inspirational teaching but also included very high level and innovative contributions to the management and development of several UK universities. We then explain how and why Geoff was an outstanding interdisciplinary river scientist and how he communicated his science through both integrative books and book chapters and also research papers that developed eight complementary research themes. Lastly, we introduce the papers in this special issue and show how they provide inputs to Geoff's areas of research interest. 相似文献
149.
This paper presents a practical procedure for obtaining creep‐free stress‐strain laws for steel exposed to fire, on the basis of codified stress‐strain laws that consider creep implicitly. The applicability of the proposed procedure has been tested on two commonly used stress‐strain laws for steel at elevated temperature, the Eurocode 3 law and a Ramberg–Osgood model, both of which have implicit consideration of creep. The simulation of two published steel coupon experiments on steel of grades S275 and S355 shows that both the Eurocode and Ramberg–Osgood stress‐strain laws produce inaccurate predictions of creep in fire at elevated temperatures. The proposed procedure was thereby used to extract the implicit creep according to the heating rates of the transient coupon tests and to derive the creep‐free stress‐strain laws. It has been shown that, by combining the creep‐free stress strain law obtained by the proposed methodology with an explicit creep model, a more realistic prediction of steel behaviour in the selected coupon test studies can be achieved. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
150.
While the issue of socialist heritage in Central and Eastern Europe has been extensively researched by scholars, this paper addresses an existing gap in theory and practice ? how safeguarding socialist cultural heritage (tangible and intangible) can be used in post-socialist towns that have little emblematic resources available today to pursue urban progress and prosperity. The paper focuses on the city of Velenje in Slovenia and its collectivist means of original production. Attention is drawn to both the importance of this aspect of its intangible cultural heritage, and the problematic nature of appealing to it, to underpin citizens’ engagement in a small-scale urban regeneration project. The paper offers insights about how using cultural heritage can be called upon to motivate citizens to participate in urban development and reform their urban identity, drawing on the recent past and living memory, through volunteered labour. 相似文献