全文获取类型
收费全文 | 2114篇 |
免费 | 141篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 12篇 |
综合类 | 3篇 |
化学工业 | 663篇 |
金属工艺 | 23篇 |
机械仪表 | 37篇 |
建筑科学 | 123篇 |
矿业工程 | 2篇 |
能源动力 | 21篇 |
轻工业 | 396篇 |
水利工程 | 28篇 |
石油天然气 | 5篇 |
无线电 | 76篇 |
一般工业技术 | 322篇 |
冶金工业 | 313篇 |
原子能技术 | 5篇 |
自动化技术 | 228篇 |
出版年
2024年 | 5篇 |
2023年 | 24篇 |
2022年 | 116篇 |
2021年 | 131篇 |
2020年 | 54篇 |
2019年 | 64篇 |
2018年 | 69篇 |
2017年 | 58篇 |
2016年 | 56篇 |
2015年 | 54篇 |
2014年 | 80篇 |
2013年 | 127篇 |
2012年 | 124篇 |
2011年 | 153篇 |
2010年 | 109篇 |
2009年 | 115篇 |
2008年 | 123篇 |
2007年 | 108篇 |
2006年 | 86篇 |
2005年 | 74篇 |
2004年 | 66篇 |
2003年 | 52篇 |
2002年 | 50篇 |
2001年 | 32篇 |
2000年 | 23篇 |
1999年 | 27篇 |
1998年 | 25篇 |
1997年 | 37篇 |
1996年 | 28篇 |
1995年 | 22篇 |
1994年 | 19篇 |
1993年 | 20篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 13篇 |
1989年 | 10篇 |
1988年 | 9篇 |
1987年 | 13篇 |
1986年 | 7篇 |
1985年 | 14篇 |
1984年 | 2篇 |
1983年 | 10篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1974年 | 3篇 |
1965年 | 1篇 |
排序方式: 共有2257条查询结果,搜索用时 46 毫秒
991.
Berwin Singh Swami Vetha Angela Guma Adam Azeez Aileru 《International journal of molecular sciences》2021,22(11)
Polyoxalate (POx) and copolyoxalate (CPOx) smart polymers are topics of interest the field of inflammation. This is due to their drug delivery ability and their potential to target reactive oxygen species (ROS) and to accommodate small molecules such as curcumin, vanilline, and p-Hydroxybenzyl alcohol. Their biocompatibility, ultra-size tunable characteristics and bioimaging features are remarkable. In this review we discuss the genesis and concept of oxylate smart polymer-based particles and a few innovative systemic delivery methods that is designed to counteract the inflammation and other aging-associated diseases (AADs). First, we introduce the ROS and its role in human physiology. Second, we discuss the polymers and methods of incorporating small molecule in oxalate backbone and its drug delivery application. Finally, we revealed some novel proof of concepts which were proven effective in disease models and discussed the challenges of oxylate polymers. 相似文献
992.
Emilia Galdiero Maria Michela Salvatore Angela Maione Elisabetta de Alteriis Anna Andolfi Francesco Salvatore Marco Guida 《International journal of molecular sciences》2021,22(7)
Candida albicans and Klebsiella pneumoniae frequently co-exist within the human host as a complex biofilm community. These pathogens are of interest because their association is also related to significantly increased morbidity and mortality in hospitalized patients. With the aim of highlighting metabolic shifts occurring in the dual-species biofilm, an untargeted GC-MS-based metabolomics approach was applied to single and mixed biofilms of C. albicans and K. pneumoniae. Metabolomic results showed that among the extracellular metabolites identified, approximately 40 compounds had significantly changed relative abundance, mainly involving central carbon, amino acid, vitamin, and secondary metabolisms, such as serine, leucine, arabitol, phosphate, vitamin B6, cyclo-(Phe-Pro), trehalose, and nicotinic acid. The results were related to the strict interactions between the two species and the different microbial composition in the early and mature biofilms. 相似文献
993.
Metal containers are used for packaging foodstuffs; more specifically, the cans used for preserving fruit have a plain body with side seam protected by a lacquer film. The traditionally used side stripe is adopted “out of abundance of caution”, as the tin present on the seam is removed by the welding process. Not using a side stripe would have practical/functional benefits for the entire production chain, with consequent reduction in the cost of the containers and in their environmental impact. Packaging of medium‐acidity products in tinplate cans is based on the principle of cathodic protection of steel by tin. To ensure that this condition persists throughout the product's shelf life, it is necessary for the anode area to be larger than the cathode area. When the seam is protected with lacquer, this condition is met. In cans where no side stripe is applied on the inner seam, the cathode area increases; this could lead to an increase in corrosion rate and consequent reduction of shelf life. However, the use of tinplate with high tin coating weight (D 11.2 g/m2) can limit this effect, under suitable packaging conditions (absence of oxygen). The aim of this study is to analyze the possibility of using cans without lacquer stripe on the electric side seam for the packaging of fruit and, more generally, of medium‐acidity products. Electrochemical measurements of model‐systems, and pack tests were used in the study. 相似文献
994.
Controllable,Wide‐Ranging n‐Doping and p‐Doping of Monolayer Group 6 Transition‐Metal Disulfides and Diselenides
下载免费PDF全文
![点击此处可从《Advanced materials (Deerfield Beach, Fla.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Siyuan Zhang Heather M. Hill Karttikay Moudgil Curt A. Richter Angela R. Hight Walker Stephen Barlow Seth R. Marder Christina A. Hacker Sujitra J. Pookpanratana 《Advanced materials (Deerfield Beach, Fla.)》2018,30(36)
Developing processes to controllably dope transition‐metal dichalcogenides (TMDs) is critical for optical and electrical applications. Here, molecular reductants and oxidants are introduced onto monolayer TMDs, specifically MoS2, WS2, MoSe2, and WSe2. Doping is achieved by exposing the TMD surface to solutions of pentamethylrhodocene dimer as the reductant (n‐dopant) and “Magic Blue,” [N(C6H4‐p‐Br)3]SbCl6, as the oxidant (p‐dopant). Current–voltage characteristics of field‐effect transistors show that, regardless of their initial transport behavior, all four TMDs can be used in either p‐ or n‐channel devices when appropriately doped. The extent of doping can be controlled by varying the concentration of dopant solutions and treatment time, and, in some cases, both nondegenerate and degenerate regimes are accessible. For all four TMD materials, the photoluminescence intensity; for all four materials the PL intensity is enhanced with p‐doping but reduced with n‐doping. Raman and X‐ray photoelectron spectroscopy (XPS) also provide insight into the underlying physical mechanism by which the molecular dopants react with the monolayer. Estimates of changes of carrier density from electrical, PL, and XPS results are compared. Overall a simple and effective route to tailor the electrical and optical properties of TMDs is demonstrated. 相似文献
995.
Intracellular Delivery: Redox‐Triggered Release of Moxifloxacin from Mesoporous Silica Nanoparticles Functionalized with Disulfide Snap‐Tops Enhances Efficacy Against Pneumonic Tularemia in Mice (Small 27/2016)
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
996.
R. Blasco T. Blanco A. Marco A. Berbegal R. Casas 《Behaviour & Information Technology》2016,35(4):304-318
Identification of user needs is an essential phase in the early stages of every design project. Many needs identification methodologies are described in the literature. When targeting users with special needs, the task becomes more challenging for different reasons (difficulty of retrieving information, performing prototype testing, etc.). This article presents a novel methodology, Needs Identification Methodology for Inclusive Design (NIMID), that guides the process of needs identification in the inclusive design scenario considering users’ physical, sensorial and cognitive capabilities. NIMID is grounded in Abowd and Beale's human–computer interaction framework and uses WHO's International Classification of Functionalities as the taxonomy that provides a common language. We exemplify the application of the methodology in the design of a smart oven for elderly people. We also compare NIMID with other methodologies evidencing its strong points: universality (common international classification of functioning language), systematicity (clearly defined phases and outcomes) and rationality (grounded in well-established interaction theory). 相似文献
997.
A new 3D parallel SPH scheme for free surface flows 总被引:3,自引:0,他引:3
We propose a new robust and accurate SPH scheme, able to track correctly complex three-dimensional non-hydrostatic free surface flows and, even more important, also able to compute an accurate and little oscillatory pressure field. It uses the explicit third order TVD Runge-Kutta scheme in time, following Shu and Osher [Shu C-W, Osher S. Efficient implementation of essentially non-oscillatory shock-capturing schemes. J Comput Phys 1988;89:439-71], together with the new key idea of introducing a monotone upwind flux for the density equation, thus removing any artificial viscosity term. For the discretization of the velocity equation, the non-diffusive central flux has been used. A new flexible approach to impose the boundary conditions at solid walls is also proposed. It can handle any moving rigid body with arbitrarily irregular geometry. It does neither produce oscillations in the fluid pressure in proximity of the interfaces, nor does it have a restrictive impact on the stability condition of the explicit time stepping method, unlike the repellent boundary forces of Monaghan [Monaghan JJ. Simulating free surface flows with SPH. J Comput Phys 1994;110:399-406]. To asses the accuracy of the new SPH scheme, a 3D mesh-convergence study is performed for the strongly deforming free surface in a 3D dam-break and impact-wave test problem providing very good results.Moreover, the parallelization of the new 3D SPH scheme has been carried out using the message passing interface (MPI) standard, together with a dynamic load balancing strategy to improve the computational efficiency of the scheme. Thus, simulations involving millions of particles can be run on modern massively parallel supercomputers, obtaining a very good performance, as confirmed by a speed-up analysis. The 3D applications consist of environmental flow problems, such as dam-break flows and impact flows against a wall. The numerical solutions obtained with our new 3D SPH code have been compared with either experimental results or with other numerical reference solutions, obtaining in all cases a very satisfactory agreement. 相似文献
998.
Ives Solano Araujo Eliane Angela Veit Marco Antonio Moreira 《Computers & Education》2008,50(4):1128-1140
The purpose of this study was to investigate undergraduate students’ performance while exposed to complementary computational modelling activities to improve physics learning, using the softwares Modellus. Interpretation of kinematics graphs was the physics topic chosen for investigation. The theoretical framework adopted was based on Halloun’s schematic modelling approach and on Ausubel’s meaningful learning theory. The results of this work show that there was a statistically significant improvement in the experimental group students’ performance when compared to the control group, submitted just to a conventional teaching method. Students’ perception with respect to the concepts and mathematical relations, as well as the motivation to learn, originated by the activities, have played a fundamental role in these findings. 相似文献
999.
1000.
Francesco Milano Angela Punzi Roberta Ragni Massimo Trotta Gianluca M. Farinola 《Advanced functional materials》2019,29(21)
A critical selection of the recent literature reports on the use of photosynthetic and photoresponsive bacteria as a source of materials for optoelectronics and photonic devices is discussed, together with the applications foreseen in solar energy conversion and storage and light information technologies. The use of both photoactive cellular components and entire living cells is reviewed, aiming to highlight the great conceptual impact of these studies. These studies point out possible deep changes in the paradigm of design, and synthesis of materials and devices for optoelectronics. Although the possible technological impact of this technology is still hard to be predicted, these studies advance the understanding of photonics of living organisms and develop new intriguing concepts in biomaterials research. 相似文献