全文获取类型
收费全文 | 22092篇 |
免费 | 662篇 |
国内免费 | 71篇 |
专业分类
电工技术 | 312篇 |
综合类 | 40篇 |
化学工业 | 3994篇 |
金属工艺 | 439篇 |
机械仪表 | 542篇 |
建筑科学 | 1061篇 |
矿业工程 | 54篇 |
能源动力 | 416篇 |
轻工业 | 2399篇 |
水利工程 | 162篇 |
石油天然气 | 41篇 |
武器工业 | 1篇 |
无线电 | 2002篇 |
一般工业技术 | 3353篇 |
冶金工业 | 4698篇 |
原子能技术 | 243篇 |
自动化技术 | 3068篇 |
出版年
2023年 | 90篇 |
2022年 | 186篇 |
2021年 | 330篇 |
2020年 | 220篇 |
2019年 | 286篇 |
2018年 | 376篇 |
2017年 | 306篇 |
2016年 | 432篇 |
2015年 | 334篇 |
2014年 | 519篇 |
2013年 | 1182篇 |
2012年 | 848篇 |
2011年 | 1112篇 |
2010年 | 866篇 |
2009年 | 847篇 |
2008年 | 938篇 |
2007年 | 929篇 |
2006年 | 780篇 |
2005年 | 731篇 |
2004年 | 618篇 |
2003年 | 539篇 |
2002年 | 534篇 |
2001年 | 474篇 |
2000年 | 452篇 |
1999年 | 490篇 |
1998年 | 1298篇 |
1997年 | 840篇 |
1996年 | 642篇 |
1995年 | 492篇 |
1994年 | 404篇 |
1993年 | 430篇 |
1992年 | 288篇 |
1991年 | 218篇 |
1990年 | 241篇 |
1989年 | 225篇 |
1988年 | 235篇 |
1987年 | 176篇 |
1986年 | 176篇 |
1985年 | 236篇 |
1984年 | 206篇 |
1983年 | 157篇 |
1982年 | 140篇 |
1981年 | 181篇 |
1980年 | 162篇 |
1979年 | 179篇 |
1978年 | 114篇 |
1977年 | 179篇 |
1976年 | 221篇 |
1975年 | 113篇 |
1973年 | 108篇 |
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
991.
The influence of temperature on the impact behavior of unidirectional glass fiber-epoxy composite was studied in the range of −20 and 150°C using a 3-point drop weight test at a constant impact velocity of 2.2 m/s (5 mph). The impact energy per unit deformed volume was found to be very sensitive to the ratio length/thickness of the specimens. When the ratio was 4, the impacted specimens exhibited extensive delamination (shear failure) and the energy absorbed by the composite was about 14 MJ/m3 between −20 and 100°C, and 18 MJ/m3 at 150°C. At length/thickness above 16 the failure was mostly in tension, and the impact energy approached a constant value of about 3.5 MJ/m3, independent of temperature. 相似文献
992.
Tingting Gu Jesper Just Katrine Tang Stenz Yan Yan Peter Sieljacks Jakob Wang Thomas Skjaerlund Groennebaek Jesper Emil Jakobsgaard Emil Rindom Jon Herskind Anders Gravholt Thomas Ravn Lassen Mathias Jrgensen Rikke Bk Eugenio Gutirrez-Jimnez Nina Kerting Iversen Peter Mondrup Rasmussen Jens Randel Nyengaard Malene Mller Jrgensen Frank de Paoli Hans Erik Btker Jrgen Kjems Kristian Vissing Kim Ryun Drasbek 《International journal of molecular sciences》2022,23(6)
Ischemic conditioning and exercise have been suggested for protecting against brain ischemia-reperfusion injury. However, the endogenous protective mechanisms stimulated by these interventions remain unclear. Here, in a comprehensive translational study, we investigated the protective role of extracellular vesicles (EVs) released after remote ischemic conditioning (RIC), blood flow restricted resistance exercise (BFRRE), or high-load resistance exercise (HLRE). Blood samples were collected from human participants before and at serial time points after intervention. RIC and BFRRE plasma EVs released early after stimulation improved viability of endothelial cells subjected to oxygen-glucose deprivation. Furthermore, post-RIC EVs accumulated in the ischemic area of a stroke mouse model, and a mean decrease in infarct volume was observed for post-RIC EVs, although not reaching statistical significance. Thus, circulating EVs induced by RIC and BFRRE can mediate protection, but the in vivo and translational effects of conditioned EVs require further experimental verification. 相似文献
993.
994.
Jochen Aβfalg 《国际自动化与计算杂志》2007,4(2):141-148
This paper presents an internal model approach for modeling and diagnostic functionality design for nonlinear systems operating subject to single- and multiple-faults. We therefore provide the framework of structured augmented state models. Fault characteristics are considered to be generated by dynamical exosystems that are switched via equality constraints to overcome the augmented state observability limiting the number of diagnosable faults. Based on the proposed model, the fault diagnosis problem is specified as an optimal hybrid augmented state estimation problem. Sub-optimal solutions are motivated and exemplified for the fault diagnosis of the well-known three-tank benchmark. As the considered class of fault diagnosis problems is large, the suggested approach is not only of theoretical interest but also of high practical relevance. 相似文献
995.
996.
Jie Yuan Ning Song Nabil Farhat Jan Van der Spiegel 《Analog Integrated Circuits and Signal Processing》2009,59(3):287-300
The clustering of spatio-temporal patterns are essential for many applications. Established from the biological analogy of
the cortex, the parametrically coupled logistic map network (PCLMN) provides a viable solution to the clustering problem.
To engineer for a single-chip spatio-temporal pattern clustering system, the highly modular PCLMN is designed in analog circuit.
In this paper, the 0.6 μm 5 V CMOS design of the processing element is presented. The analog design employs self-calibration
techniques to improve the accuracy and robustness of the nonlinear circuits. A fabricated element covers a die area of 0.55
mm2, and consumes 240 mW power at 5 V supply. After calibration, simulation and testing results show that the element fulfills
the system-level requirement of the Cort-X model for driving signals up to 1 MHz. 相似文献
997.
In this paper we investigate the position of a review network within a research specialty; the network of scholars who write
reviews of their colleagues’ work. This is one of the voluntary activities that researchers perform as a prerequisite for
the functioning of the invisible college. We compare this network to other networks within the specialty, and this allows
us to distinguish various roles: stars, influentials, members, reviewers and juniors. As scholars are characterized by different role-configurations, the invisible college becomes stratified. We discuss the
implications for the development of a referee factor and review factor, norms for refereeing and reviewing, and the development
of systems-based research evaluations. 相似文献
998.
In this article, we extend the classical maximal covering model in a competitive environment by including a price decision.
We formulate a revenue maximization model and propose two procedures to solve it. By a careful examination of the relationships
between the maximal covering problems for different prices, we reveal interesting properties of the deduced revenue maximization
model, leading to a full enumeration solution approach. With the help of two more properties we develop a second, more intelligent
solution procedure. Computational experiments show promising results for a small, medium and large case study. 相似文献
999.
Utilisation possibility of Enterococcus faecalis isolates from neonate's faeces for production of fermented sausages as starter cultures 下载免费PDF全文
Hoa Van Ba Hyun‐Woo Seo Soo‐Hyun Cho Yoon‐Seok Kim Jin‐Hyoung Kim Beom‐Young Park Hyun‐Wook Kim Jun‐Sang Ham Pil‐Nam Seong 《International Journal of Food Science & Technology》2017,52(7):1660-1669
This study aimed at assessing the utilisation possibility of Enterococcus faecalis as starter cultures for production of fermented sausages. The E. faecalis isolates isolated from faeces samples of 5‐day‐old healthy newborn babies, identified by 16SrDNA sequencing and free from virulence determinants as proven by genomic sequencing, were used for fermented sausages production as starter culture. Six treatments (four inoculated with four different E. faecalis isolates, one with commercial starter culture and one control) were prepared. The inoculation with E. faecalis showed a stronger acidification compared with the control. The treatments with E. faecalis showed significantly higher flavour and acceptability scores in comparison with the control or commercial starter culture. Both of commercial starter culture and E. faecalis were positive with tyramine. Apart from the amine production, the inoculation with E. faecalis generally improved the acidifying activity and flavour of the products, suggesting their application potentials in fermented sausages production as starter cultures. 相似文献
1000.
With increased interest in energy efficiency in recent years, energy efficiency portfolio standards (EEPS) have gained popularity in state policymaking. This analysis employed New Jersey specific data to compare two incentive based approaches to EEPS implementation: rebates and white certificates. Quantitative modeling suggests that white certificate approaches that depend on market-clearing prices generate much larger upfront incentive outlays than rebate programs. They do not however increase societal burden. Both programs overcome high upfront efficiency measure costs and both recoup the expenses over the long run. Administration costs and participation rates can affect this dynamic however and require additional research to determine which approaches are most cost effective for various energy efficiency measures. 相似文献