全文获取类型
收费全文 | 519830篇 |
免费 | 14884篇 |
国内免费 | 5482篇 |
专业分类
电工技术 | 13466篇 |
技术理论 | 11篇 |
综合类 | 6924篇 |
化学工业 | 80533篇 |
金属工艺 | 19835篇 |
机械仪表 | 18446篇 |
建筑科学 | 20176篇 |
矿业工程 | 3942篇 |
能源动力 | 14097篇 |
轻工业 | 50254篇 |
水利工程 | 5006篇 |
石油天然气 | 7995篇 |
武器工业 | 704篇 |
无线电 | 68654篇 |
一般工业技术 | 89743篇 |
冶金工业 | 80435篇 |
原子能技术 | 6769篇 |
自动化技术 | 53206篇 |
出版年
2022年 | 4303篇 |
2021年 | 6585篇 |
2020年 | 4794篇 |
2019年 | 4951篇 |
2018年 | 6741篇 |
2017年 | 7201篇 |
2016年 | 6999篇 |
2015年 | 7213篇 |
2014年 | 10529篇 |
2013年 | 25338篇 |
2012年 | 16603篇 |
2011年 | 21664篇 |
2010年 | 17385篇 |
2009年 | 18861篇 |
2008年 | 19894篇 |
2007年 | 19805篇 |
2006年 | 18629篇 |
2005年 | 17242篇 |
2004年 | 15125篇 |
2003年 | 14355篇 |
2002年 | 13665篇 |
2001年 | 13764篇 |
2000年 | 13027篇 |
1999年 | 14069篇 |
1998年 | 26744篇 |
1997年 | 19999篇 |
1996年 | 16066篇 |
1995年 | 12812篇 |
1994年 | 11249篇 |
1993年 | 10524篇 |
1992年 | 8030篇 |
1991年 | 7481篇 |
1990年 | 6956篇 |
1989年 | 6570篇 |
1988年 | 6229篇 |
1987年 | 5159篇 |
1986年 | 5028篇 |
1985年 | 6138篇 |
1984年 | 5700篇 |
1983年 | 4906篇 |
1982年 | 4574篇 |
1981年 | 4499篇 |
1980年 | 4250篇 |
1979年 | 4110篇 |
1978年 | 3789篇 |
1977年 | 4569篇 |
1976年 | 6129篇 |
1975年 | 3124篇 |
1974年 | 3016篇 |
1973年 | 2899篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
S.K. Vimala Bharathi M. Maria Leena J.A. Moses C. Anandharamakrishnan 《International Journal of Food Science & Technology》2020,55(3):1238-1245
The usage of cling wraps is emerging as an easy and cost-effective approach to protect fresh-cut fruits and vegetables from dust, whilst improving visual appeal on retail counters. This study focused on developing an alternate, protein-based packaging material as a food grade cling wrap for food packaging applications. Zein-based cling wraps were produced, and their physical and mechanical characteristics were evaluated and compared with conventionally used chitosan biopolymer films and commercial synthetic polymer films. Antioxidant potential of the prepared films was studied, and the effectiveness of the developed films as anti-browning cling wraps was evaluated using studies conducted on fresh-cut apple slices at ambient conditions. Anti-browning effects were in par with polymeric counterparts; however, zein cling wraps could better prevent weight loss in apple slices. Zein-based films can be adopted as biodegradable food grade cling wraps as an alternative to chitosan and synthetic polymeric materials. 相似文献
182.
183.
184.
Application of high‐temperature Fenton oxidation for the treatment of sulfonation plant wastewater
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)
185.
Crespo Juan-José Sánchez José L. Alfaro-Cortés Francisco J. Flich José Duato José 《The Journal of supercomputing》2021,77(11):12826-12856
The Journal of Supercomputing - Deadlock-free dynamic network reconfiguration process is usually studied from the routing algorithm restrictions and resource reservation perspective. The dynamic... 相似文献
186.
A device able to electrokinetically concentrate cationic samples has many potential medical and industrial applications, but until now has remained undeveloped due to the lack of a commercial anion-permselective material leading to a prohibitively complex fabrication procedure. Herein, a novel multiscale-porous anion exchange membrane (MP-AEM) that enables the convenient and scalable electrokinetic concentration of cationic species is proposed. A mechanically enhanced multiscale-porous structure with a solid framework is realized by adopting polyester resin as an additive to overcome the intrinsic limitations of the AEM material. The scalable MP-AEM-embedded electrokinetic concentrator is devised based on the peculiar properties of the MP-AEM that for allow both ion and fluid transport. With the MP-AEM, the concentrator is fabricated in a highly streamlined manner consisting only of a simple insertion and assembly. The concentration performance of the MP-AEM-embedded electrokinetic concentrator is demonstrated with a positively charged fluorescent dye and a fluorescein-labeled protein, and the results show enrichment factors of 250 and 500, respectively. The MP-AEM makes cationic electrokinetic concentration more accessible and scalable, thereby enabling further progress in a wide range of fields. 相似文献
187.
We show that in the presence of magnetic field, two superconducting phases with the center-of-mass momentum of Cooper pair parallel to the magnetic field are induced in Dresselhaus spin–orbit-coupled superconductor. Specifically, at small magnetic field, the center-of-mass momentum is induced due to the energy-spectrum distortion and no unpairing region with vanishing singlet correlation appears. We refer to this superconducting state as the drift-BCS state. By further increasing the magnetic field, the superconducting state falls into the Fulde–Ferrell state with the emergence of the unpairing regions. The observed abrupt enhancement of the center-of-mass momenta and suppression on the order parameters during the transition indicate the occurrence of a first-order phase transition. Enhanced Pauli limit and hence enlarged magnetic-field regime of the Fulde–Ferrell state, due to the spin-flip terms of the spin–orbit coupling, are revealed. We also address the triplet correlations induced by the spin–orbit coupling, and show that the Cooper-pair spin polarizations, generated by the magnetic field and center-of-mass momentum with the triplet correlations exhibit totally different magnetic-field dependences between the drift-BCS and Fulde–Ferrell states. 相似文献
188.
189.
Yao Dajie Liu Xiaofei Wu Jian 《International Journal of Control, Automation and Systems》2020,18(9):2251-2258
International Journal of Control, Automation and Systems - In this paper, the tracking problem for a class of uncertain nonlinearly parameterized systems with input delay based the adaptive... 相似文献
190.
H.C. Weigele L. Gygax A. Steiner B. Wechsler J.-B. Burla 《Journal of dairy science》2018,101(3):2370-2382
Lameness is one of the most prevalent diseases affecting the welfare of cows in modern dairy production. Lameness leads to behavioral changes in severely lame cows, which have been investigated in much detail. For early detection of lameness, knowledge of the effects of moderate lameness on cow behavior is crucial. Therefore, the behavior of nonlame and moderately lame cows was compared on 17 Swiss dairy farms. On each farm, 5 to 11 nonlame (locomotion score 1 of 5) and 2 to 7 moderately lame (locomotion score 3 of 5) cows were selected for data collection in two 48-h periods (A, B) separated by an interval of 6 to 10 wk. Based on visual locomotion scoring, 142 nonlame and 66 moderately lame cows were examined in period A and 128 nonlame and 53 moderately lame cows in period B. Between these 2 periods, the cows underwent corrective hoof trimming. Lying behavior, locomotor activity, and neck activity were recorded by accelerometers (MSR145 data logger, MSR Electronics GmbH, Seuzach, Switzerland), and feeding and rumination behaviors by noseband sensors (RumiWatch halter, ITIN + HOCH GmbH, Liestal, Switzerland). Furthermore, visits to the brush and the concentrate feeder, and the milking order position were recorded. In comparison with nonlame cows, moderately lame cows had a longer lying duration, a longer average lying bout duration, and a greater lateral asymmetry in lying duration. Average locomotor activity, locomotor activity during 1 h after feed delivery or push-ups, and average neck activity were lower in moderately lame cows. Eating time and the number of eating chews (jaw movements) were reduced in moderately lame compared with nonlame cows, whereas no effect of moderate lameness was evident for ruminating time, number of ruminating chews and boluses, and average number of ruminating chews per bolus. Moderately lame cows visited the concentrate feeder and the brush less frequently, and they were further back in the milking order compared with nonlame cows. In conclusion, nonlame and moderately lame cows differed in a biologically relevant way in many of the behavioral variables investigated in this study. Therefore, the use of these behavioral changes seems to be promising to develop a tool for early lameness detection. 相似文献