全文获取类型
收费全文 | 2619篇 |
免费 | 67篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 46篇 |
综合类 | 9篇 |
化学工业 | 790篇 |
金属工艺 | 36篇 |
机械仪表 | 77篇 |
建筑科学 | 121篇 |
矿业工程 | 2篇 |
能源动力 | 100篇 |
轻工业 | 292篇 |
水利工程 | 11篇 |
石油天然气 | 6篇 |
武器工业 | 1篇 |
无线电 | 237篇 |
一般工业技术 | 462篇 |
冶金工业 | 86篇 |
原子能技术 | 19篇 |
自动化技术 | 395篇 |
出版年
2024年 | 40篇 |
2023年 | 43篇 |
2022年 | 152篇 |
2021年 | 180篇 |
2020年 | 80篇 |
2019年 | 81篇 |
2018年 | 86篇 |
2017年 | 75篇 |
2016年 | 88篇 |
2015年 | 75篇 |
2014年 | 117篇 |
2013年 | 176篇 |
2012年 | 117篇 |
2011年 | 185篇 |
2010年 | 138篇 |
2009年 | 121篇 |
2008年 | 124篇 |
2007年 | 110篇 |
2006年 | 90篇 |
2005年 | 72篇 |
2004年 | 70篇 |
2003年 | 60篇 |
2002年 | 56篇 |
2001年 | 34篇 |
2000年 | 26篇 |
1999年 | 29篇 |
1998年 | 30篇 |
1997年 | 33篇 |
1996年 | 24篇 |
1995年 | 17篇 |
1994年 | 16篇 |
1993年 | 14篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1985年 | 6篇 |
1984年 | 15篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1979年 | 10篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1974年 | 4篇 |
1967年 | 3篇 |
1966年 | 3篇 |
排序方式: 共有2690条查询结果,搜索用时 671 毫秒
991.
Bahman Delalat Chiara Cozzi Soraya Rasi Ghaemi Giovanni Polito Frederik H. Kriel Thomas Danny Michl Frances J. Harding Craig Priest Giuseppe Barillaro Nicolas H. Voelcker 《Advanced functional materials》2018,28(28)
Microfluidic 3D cell culture is a promising technology for the screening of drug toxicity profiles. In this study, a bioartificial liver consisting of a surface‐engineered microfluidic silicon chip with microtrenches mimicking hepatic sinusoids is shown to extend 3D primary hepatocyte culture and improve in vitro drug screening for hepatotoxicity, with respect to the state‐of‐the‐art literature on this subject. Primary hepatocytes hosted in the 3D heparin‐coated microtrenches (the bioartificial liver) secrete high levels of albumin and urea over 4 weeks. The cytotoxicity of common drugs, namely, acetaminophen, chlorpromazine, and tacrine, was assessed on primary hepatocytes both at day 1 and day 7. The results suggest that mimicking hepatic sinusoids using a microtrench format allows the maintenance of difficult‐to‐culture primary hepatocytes to be extended to 4 weeks and provides an alternative model to animal studies for the screening of the cytotoxicity of new drugs. 相似文献
992.
In parts manufactured by injection molding, the regions affected by the presence of a weld line show worse mechanical properties, especially in the case of fiber-reinforced thermoplastics. This is mainly due to the unfavorable reinforcement orientation in the proximity of the weld line. The position and shape of a weld line, which develops where two different flows converge during the mold filling phase, can be modified by generating a pressure unbalance between flow fronts during the packing phase. This phenomenon is also known as “inflow” in the literature. In this work, the inflow phenomenon was obtained using side features located near the weld line. Its effect on weld line morphology and fibers orientation was investigated. The experimental results show that the inflow can modify the weld line position and shape. Furthermore, it can reorient the fibers in the weld line region, increasing the load at break and stiffness of the weld line by 19% and 15%, respectively. These effects were numerically modeled with a maximum error of 4%. 相似文献
993.
Zlatica Marinković Giovanni Crupi Alina Caddemi Vera Marković Dominique M.M.-P. Schreurs 《International Journal of Numerical Modelling》2020,33(3):e2668
The purpose of this paper is to provide a comprehensive overview of the field-effect transistor (FET) small-signal modeling using artificial neural networks (ANNs). To gain an in-depth insight into how to effectively develop an ANN model, we present a comparative study on the application of the ANNs for modeling the scattering (S-) parameters of a variety of FET technologies versus bias point, ambient temperature, and geometrical dimensions. As will be shown, the main challenge consists of identifying the most appropriate ANN model for the specific case under study. This is because the performance of an ANN-based model can vary significantly, depending especially on the choice of the model structure and the size and parameters of the chosen ANN. In addition, the choice of the model is related directly to the behavior of the FET characteristics, which might greatly depend on the selected device technology and operating conditions. The analysis of the present comparative study allows understanding how to properly construct ANN models to perform at their best for a successful FET modeling. 相似文献
994.
Diego O. Sanchez Ramirez Monica Periolatto Riccardo A. Carletto Alessio Varesano Claudia Vineis Cinzia Tonetti Roberta Bongiovanni 《加拿大化工杂志》2020,98(7):1483-1494
Chitosan was grafted on the surface of a cotton gauze (20, 50, and 100 mg chitosan g−1 cotton) to improve its stability in aqueous solutions. The adsorption of hexavalent chromium ions from water on the grafted chitosan was evaluated to determine, by means of linear and nonlinear models, the kinetic and isotherm adsorption of the process. The kinetics of pseudo second-order, pseudo first-order, and adsorption isotherms type II were obtained, that is, a monolayer adsorption on nonporous adsorbents with physical adsorption was present. The most probable energy of adsorption corresponded to a physisorption with hydrogen bond interactions between chromium ions and ammonium groups. Moreover, three different cross-sectional areas of hexavalent chromium ions were calculated and used to estimate the specific surface area employed by active sites to adsorb metal ions in terms of chitosan or cotton mass. Finally, the percentage of the area occupied by chromium ions on the surface was estimated by dividing the resulting specific surface area in terms of cotton mass by the specific surface area of cotton reported in literature. As a result, it was determined that the occupied area is between 6% (for 20 mg chitosan g−1 cotton)-24% (for 100 mg chitosan g−1 cotton) from the total area of cotton. 相似文献
995.
996.
Nageshvar Patel Matteo Bergamaschi Massimo Cagnin Giovanni Bittante 《International Journal of Food Science & Technology》2020,55(3):1046-1056
Minerals in meat vary with different extrinsic and intrinsic sources; therefore, we aimed to quantify different sources of variation in mineral profile of beef. Longissimus thoracis muscle (N.182) from young bulls and heifers was analysed using ICP-OES for 6 macrominerals, 5 essential microminerals and 9 environmental microminerals. Results of mixed models show that breed and sex have little effect on mineral profile. Major sources of variation, such as farm, individual animal within farm and side/sample within animal, differed markedly from mineral to mineral, affecting reproducibility coefficients. Multivariate factor analysis revealed that five latent factors explained 69% of the co-variance of 20 minerals. The first was a quantitative factor, followed by others based on Na-Fe-Cu, on K-B-Pb, on Fe-Mn and on Zn content, respectively. In conclusion, minerals’ major source of variation depends on complex relationships between the animal’s genetics, physiology, farm environment, management and feeding, whose understanding is favoured by latent factor analyses. 相似文献
997.
Giovanni Venâncio Rogério C. Turchetti Edson T. Camargo Elias P. Duarte Jr 《International Journal of Network Management》2021,31(3):e2124
Software-defined networks (SDN) usually rely on a centralized controller, which has limited availability and scalability by definition. Although a solution is to employ a distributed control plane, the main issue with this approach is how to maintain the consistency among multiple controllers. Consistency should be achieved with as low impact on network performance as possible and should be transparent for controllers, without requiring any change of the SDN protocols. In this work, we propose VNF-Consensus, a virtual network function that implements Paxos to ensure strong consistency among controllers of a distributed control plane. In our solution, controllers can perform their control plane activities without having to execute the expensive tasks required to keep consistency. Experimental results are presented showing the cost and benefits of the proposed solution, in particular in terms of low controller overhead. 相似文献
998.
Zefang Hao;Yan Qu;Jiajun Huang;Giovanni Crupi;Jialin Cai; 《International Journal of Numerical Modelling》2024,37(2):e3204
In this paper, an automatic multi-objective particle swarm optimization (AMOPSO) method is developed for the design of Doherty power amplifiers (DPAs). In comparison to the well-known built-in optimizer available in commercial simulators, the proposed method not only reduces the optimization time, but also provides superior power added efficiency (PAE) for the final power amplifier. According to the reported measurements, the output PAE of the fabricated DPA exceeds 50% at 6 dB backoff, the saturated PAE is more than 61%, and the saturated output power (Pout) is over 43 dBm in the target frequency range of 1.9–2.1 GHz. As compared with existing optimization methods, the proposed method allows reducing optimization time by more than 37%. 相似文献
999.
Shuhao Cheng;Xiaoqiang Tang;Zlatica Marinković;Giovanni Crupi;Jialin Cai; 《International Journal of Numerical Modelling》2024,37(2):e3201
This paper presents a novel poly-harmonic distortion (PHD) model that incorporates the DC input and output bias voltages using Gaussian process regression (GPR). Simulation tests were conducted using a 10-W gallium nitride (GaN) HEMT transistor from Wolfspeed, and the model implementation test was performed in the Keysight Advanced Design System environment. The results showed that the GPR-based PHD model exhibited good performance in predicting both fundamental and harmonic behaviors over a wide range of bias variations with significant advantages over basic linear regression methods. Additionally, the model accurately predicted load-pull simulations. The measurement test was conducted using a 6-W GaN device, and the results showed a mean error of 2.22% and 4.54% for the fundamental and second harmonic of the reflected wave, respectively. 相似文献
1000.