全文获取类型
收费全文 | 3113篇 |
免费 | 219篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 62篇 |
综合类 | 1篇 |
化学工业 | 798篇 |
金属工艺 | 42篇 |
机械仪表 | 72篇 |
建筑科学 | 151篇 |
矿业工程 | 1篇 |
能源动力 | 101篇 |
轻工业 | 245篇 |
水利工程 | 10篇 |
石油天然气 | 3篇 |
武器工业 | 1篇 |
无线电 | 292篇 |
一般工业技术 | 575篇 |
冶金工业 | 130篇 |
原子能技术 | 27篇 |
自动化技术 | 825篇 |
出版年
2024年 | 5篇 |
2023年 | 29篇 |
2022年 | 91篇 |
2021年 | 148篇 |
2020年 | 76篇 |
2019年 | 89篇 |
2018年 | 98篇 |
2017年 | 92篇 |
2016年 | 143篇 |
2015年 | 113篇 |
2014年 | 145篇 |
2013年 | 219篇 |
2012年 | 202篇 |
2011年 | 230篇 |
2010年 | 192篇 |
2009年 | 191篇 |
2008年 | 177篇 |
2007年 | 165篇 |
2006年 | 120篇 |
2005年 | 94篇 |
2004年 | 117篇 |
2003年 | 97篇 |
2002年 | 63篇 |
2001年 | 54篇 |
2000年 | 43篇 |
1999年 | 37篇 |
1998年 | 28篇 |
1997年 | 23篇 |
1996年 | 34篇 |
1995年 | 26篇 |
1994年 | 24篇 |
1993年 | 19篇 |
1992年 | 19篇 |
1991年 | 10篇 |
1990年 | 6篇 |
1989年 | 11篇 |
1988年 | 2篇 |
1987年 | 12篇 |
1986年 | 6篇 |
1985年 | 15篇 |
1984年 | 17篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1975年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有3336条查询结果,搜索用时 375 毫秒
111.
Daniela dell'Oro Francesco Casamassima Giuseppe Gesualdo Marco Iammarino Paolo Mambelli Valeria Nardelli 《International Journal of Food Science & Technology》2014,49(5):1391-1400
The aim of this study was to develop and validate an efficient analytical method based on gas chromatography/tandem mass spectrometry (GC/MS/MS) for detection and quantification of six pyrethroids residues (Phenothrin, Permethrin, Cyfluthrin, Cypermethrin, Deltamethrin and Fenvalerate) in chicken eggs. The method was based on a preliminary liquid–liquid extraction of albumen‐free yolk samples, followed by a clean‐up by solid‐phase extraction. GC/MS/MS analyses were carried out in the selected reaction monitoring mode. Validation parameters such as specificity, detection capability, decision limit, precision, recovery, stability and ruggedness were determined, resulting in compliance with Decision 2002/657/EC. No complicated apparatus are required; moreover, low volumes of organic solvents and a nonintensive manual labour are required. These low costs and simple procedure, based on rapid and safe operations, may represent a useful tool in the routine analysis of pyrethroids pesticides, in the place of the currently used conventional techniques. 相似文献
112.
Cinzia Stigliano Melissa D. Landis Daniel Y. Lee Paolo Decuzzi 《Small (Weinheim an der Bergstrasse, Germany)》2014,10(13):2688-2696
Hybrid PET/MRI scanners have the potential to provide fundamental molecular, cellular, and anatomic information essential for optimizing therapeutic and surgical interventions. However, their full utilization is currently limited by the lack of truly multi‐modal contrast agents capable of exploiting the strengths of each modality. Here, we report on the development of long‐circulating positron‐emitting magnetic nanoconstructs (PEM) designed to image solid tumors for combined PET/MRI. PEMs are synthesized by a modified nano‐precipitation method mixing poly(lactic‐co‐glycolic acid) (PLGA), lipids, and polyethylene glycol (PEG) chains with 5 nm iron oxide nanoparticles (USPIOs). PEM lipids are coupled with 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (DOTA) and subsequently chelated to 64Cu. PEMs show a diameter of 140 ± 7 nm and a transversal relaxivity r2 of 265.0 ± 10.0 (mM × s)?1, with a r2/r1 ratio of 123. Using a murine xenograft model bearing human breast cancer cell line (MDA‐MB‐231), intravenously administered PEMs progressively accumulate in tumors reaching a maximum of 3.5 ± 0.25% ID/g tumor at 20 h post‐injection. Correlation of PET and MRI signals revealed non‐uniform intratumoral distribution of PEMs with focal areas of accumulation at the tumor periphery. These long‐circulating PEMs with high transversal relaxivity and tumor accumulation may allow for detailed interrogation over multiple scales in a clinically relevant setting. 相似文献
113.
114.
Paolo E.Santangelo 《热科学学报(英文版)》2012,21(6):539-548
Pressure-swirl atomizers are often employed to generate a water-mist spray,typically employed in fire suppression.In the present study,an experimental characterization of dispersion(velocity and cone angle)and atomization(drop-size axial evolution)was carried out following a previously developed methodology,with specific reference to the initial region of the spray.Laser-based techniques were used to quantitatively evaluate the considered phenomena:velocity field was reconstructed through a Particle Image Velocimetry analysis;drop-size distribution was measured by a Malvern Spraytec device,highlighting secondary atomization and subsequent coalescence along the spray axis.Moreover,a comprehensive set of relations was validated as predictive of the involved parameters,following an inviscid-fluid approach.The proposed model pertains to early studies on pressure-swirl atomizers and primarily yields to determine both initial velocity and cone angle.The spray thickness is also predicted and a classic correlation for Sauter Mean Diameter is shown to provide good agreement with experimental results.The analysis was carried out at the operative pressure of 80 bar;two injectors were employed featuring different orifice diameters and flow numbers,as a sort of parametric approach to this spray typology. 相似文献
115.
116.
117.
Massimiliano Lanzi Francesco Paolo Di-Nicola Massimiliano Livi Luisa Paganin Fabio Cappelli Filippo Pierini 《Journal of Materials Science》2013,48(11):3877-3893
This article describes the preparation of thin films of conjugated polymers which can enhance their specific electrical conductivity by several orders of magnitude by changing their state from insulating to conducting materials. The examined polymers, i.e., a polyacetylenic and a polythiophenic derivative, are functionalized with thioalkylic side chains and are soluble in common organic solvents from which they lead to thick homogeneous films. The films can be deposited on different substrates, either rigid or flexible, and can be easily exposed to laser radiation to make them conductive. The process is irreversible, and the final conductivity is stable over time, even in the presence of high temperatures (up to 180 °C), moisture, and air. The high stability of treated samples, easy polymer synthesis and quick and inexpensive suitably tailored laser tracing procedure make these materials very promising for applications in organic electronics and in the development of new electronic circuitry. 相似文献
118.
Paolo Bergamo Giovanna Trinchese Chiara De Filippo Giorgio Gifuni Marcello Gaita Angelica Pignalosa Immacolata Donizzetti Rosalba Putti Rossella Di Palo Antonio Barletta Maria Pina Mollica 《Molecular nutrition & food research》2012,56(10):1596-1600
Dietary PUFA, mainly those of the n‐3 family, are known to play essential roles in the maintenance of energy balance and in the reduction of body fat deposition through the upregulation of mitochondrial uncoupling that is the main source of reactive oxygen species. We hypothesized that rat supplementation with raw donkey's milk (DM), characterized by low‐fat content and higher n3:n6 ratio, may affect energy balance, lipid metabolism, and prooxidant status as compared to animals treated with cow's milk. In the present study, the effects of drinking raw DM (for 4 weeks) on energy balance, lipid metabolism, antiinflammatory, and antioxidant/detoxifying defences was compared to that produced by rat intake of an iso‐energetic amount of raw cow's milk. The hypolipidemic effect produced by DM paralleled with the enhanced mitochondrial activity/proton leakage and with the increased activity or expression of mitochondrial markers namely, carnitine palmitoyl transferase and uncoupling protein 2. The association of decreased energy efficiency with reduced proinflammatory signs (TNF‐α and LPS levels) with the significant increase antioxidant (total thiols) and detoxifying enzyme activities (glutathione‐S‐transferase NADH quinone oxidoreductase) in DM‐treated animals, indicated that beneficial effects were attributable, at least in part, to the activation of nuclear factor 2 erythroid‐related factor 2 pathway. 相似文献
119.
Alberto Casagrande Joanna Jarmolowska Marcello Maria Turconi Pierpaolo Busan Piero Paolo Battaglini 《International journal of human-computer interaction》2018,34(12):1085-1104
One application of the P300 brain electric signal is sentence spelling, which enables subjects who have lost control of their motor pathways to communicate by selecting characters in a matrix containing all alphabet symbols. This technology still suffers from both low communication/high error rates. A P300 speller, named PolyMorph, which jointly introduces the selection matrix polymorphism (reducing the matrix size by removing useless symbols) and sentence-based predictions (which forecast words on the basis of language statistics) is presented. This is accomplished by using a custom dynamic knowledge-base, tailored to the subject lexicon, and updated in real time with the selections of the subject. The effectiveness of the presented speller is measured in vivo and in silico. The results suggest that the use of PolyMorph increases the number of spelt characters per time unit and reduces the error rate. 相似文献
120.
Adsorption Behavior of Halogenated Anesthetic and Water Vapor on Cr‐Based MOF (MIL‐101) Adsorbent. Part I. Equilibrium and Breakthrough Characterizations
下载免费PDF全文
![点击此处可从《化学,工程师,技术》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ye Hua Nicola Gargiulo Antonio Peluso Paolo Aprea Mladen Eić Domenico Caputo 《化学,工程师,技术》2016,88(11):1730-1738
A synthesized chromium‐based metal organic framework (Cr‐MOF) was used for the adsorption of halogenated anesthetics, i.e., sevoflurane (SF). Adsorption isotherm and breakthrough experiments involving SF (reference sorbate) and water vapor were measured at 298 K and atmospheric pressure on both Cr‐MOF and a commercially used reference adsorbent. The Cr‐MOF MIL‐101 showed a significantly higher SF adsorption capacity and much higher selectivity relative to water vapor compared to the reference adsorbent. Binary‐mixture breakthrough tests demonstrated a “roll‐up effect” for SF on the reference adsorbent while no such effect was observed on MIL‐101. 相似文献