全文获取类型
| 收费全文 | 1068篇 |
| 免费 | 22篇 |
| 国内免费 | 2篇 |
专业分类
| 电工技术 | 20篇 |
| 综合类 | 2篇 |
| 化学工业 | 212篇 |
| 金属工艺 | 37篇 |
| 机械仪表 | 78篇 |
| 建筑科学 | 4篇 |
| 矿业工程 | 3篇 |
| 能源动力 | 39篇 |
| 轻工业 | 47篇 |
| 水利工程 | 9篇 |
| 无线电 | 188篇 |
| 一般工业技术 | 295篇 |
| 冶金工业 | 67篇 |
| 原子能技术 | 12篇 |
| 自动化技术 | 79篇 |
出版年
| 2024年 | 33篇 |
| 2023年 | 18篇 |
| 2022年 | 20篇 |
| 2021年 | 44篇 |
| 2020年 | 38篇 |
| 2019年 | 32篇 |
| 2018年 | 31篇 |
| 2017年 | 40篇 |
| 2016年 | 42篇 |
| 2015年 | 28篇 |
| 2014年 | 42篇 |
| 2013年 | 55篇 |
| 2012年 | 74篇 |
| 2011年 | 81篇 |
| 2010年 | 45篇 |
| 2009年 | 51篇 |
| 2008年 | 44篇 |
| 2007年 | 29篇 |
| 2006年 | 32篇 |
| 2005年 | 25篇 |
| 2004年 | 34篇 |
| 2003年 | 21篇 |
| 2002年 | 35篇 |
| 2001年 | 21篇 |
| 2000年 | 19篇 |
| 1999年 | 14篇 |
| 1998年 | 29篇 |
| 1997年 | 26篇 |
| 1996年 | 9篇 |
| 1995年 | 10篇 |
| 1994年 | 11篇 |
| 1993年 | 4篇 |
| 1992年 | 4篇 |
| 1991年 | 4篇 |
| 1990年 | 6篇 |
| 1989年 | 7篇 |
| 1988年 | 3篇 |
| 1987年 | 6篇 |
| 1986年 | 6篇 |
| 1985年 | 1篇 |
| 1984年 | 1篇 |
| 1983年 | 2篇 |
| 1982年 | 1篇 |
| 1981年 | 1篇 |
| 1979年 | 1篇 |
| 1977年 | 1篇 |
| 1976年 | 2篇 |
| 1975年 | 7篇 |
| 1974年 | 1篇 |
| 1972年 | 1篇 |
排序方式： 共有1092条查询结果，搜索用时 15 毫秒
41.
David K. Hsu Kwang-Hee Im Young-Tae Cho Jae-Woung Park Jae-Ki Sim In-Young Yang 《Journal of Mechanical Science and Technology》2002,16(3):292-301
Ultrasound waves interact strongly with the orientation and sequence of the plies in a layup when propagating in the thickness direction of composite laminates. Also the layup orientation greatly influences its properties in a composite laminate. If the layup orientation of a ply is misaligned, it could result in the part being rejected and discarded. Now, most researchers cut a small coupon from the waste edge and use a microscope to optically verify the ply sequences on important parts. This may add a substantial cost to the production since the test is both labor intensive and performed after the part is cured. A nondestructive technique would be very beneficial, which could be used to test the part after curing and requires less time than the optical test. Therefore we have developed, reduced, and implemented a novel ply-by-ply vector decomposition model for composite laminates fabricated from unidirectional plies. This model decomposes the transmission of a linearly polarized ultrasound wave into orthogonal components through each ply of a laminate. High probability is found, by comparisons between the model and tests, in characterizing cured layups of the laminates by using the proposed method. 相似文献
42.
Xin He;Minkyung Kwon;Juchan Chung;Kangsik Lee;Yongjun Choi;Yeji Im;Jiung Jang;Yongjune Choi;Hyo Jae Yoon; 《Small (Weinheim an der Bergstrasse, Germany)》2024,20(44):2403537
Rechargeable batteries have transformed human lives and modern industry, ushering in new technological advancements such as mobile consumer electronics and electric vehicles. However, to fulfill escalating demands, it is crucial to address several critical issues including energy density, production cost, cycle life and durability, temperature sensitivity, and safety concerns is imperative. Recent research has shed light on the intricate relationship between these challenges and the chemical processes occurring at the electrode-electrolyte interface. Consequently, a novel approach has emerged, utilizing self-assembled molecular layers (SAMLs) of meticulously designed molecules as nanomaterials for interface engineering. This research provides a comprehensive overview of recent studies underscoring the significant roles played by SAML in rechargeable battery applications. It discusses the mechanisms and advantageous features arising from the incorporation of SAML. Moreover, it delineates the remaining challenges in SAML-based rechargeable battery research and technology, while also outlining future perspectives. 相似文献
43.
Mani Balamurugan Hui‐Yun Jeong Venkata Surya Kumar Choutipalli Jung Sug Hong Hongmin Seo Natarajan Saravanan Jun Ho Jang Kang‐Gyu Lee Yoon Ho Lee Sang Won Im Venkatesan Subramanian Sun Hee Kim Ki Tae Nam 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(25)
The electrochemical reduction of carbon dioxide (CO2) to hydrocarbons is a challenging task because of the issues in controlling the efficiency and selectivity of the products. Among the various transition metals, copper has attracted attention as it yields more reduced and C2 products even while using mononuclear copper center as catalysts. In addition, it is found that reversible formation of copper nanoparticle acts as the real catalytically active site for the conversion of CO2 to reduced products. Here, it is demonstrated that the dinuclear molecular copper complex immobilized over graphitized mesoporous carbon can act as catalysts for the conversion of CO2 to hydrocarbons (methane and ethylene) up to 60%. Interestingly, high selectivity toward C2 product (40% faradaic efficiency) is achieved by a molecular complex based hybrid material from CO2 in 0.1 m KCl. In addition, the role of local pH, porous structure, and carbon support in limiting the mass transport to achieve the highly reduced products is demonstrated. Although the spectroscopic analysis of the catalysts exhibits molecular nature of the complex after 2 h bulk electrolysis, morphological study reveals that the newly generated copper cluster is the real active site during the catalytic reactions. 相似文献
44.
Abu Talha Aqueel Ahmed Sambhaji M. Pawar Akbar I. Inamdar Hyungsang Kim Hyunsik Im 《Advanced Materials Interfaces》2020,7(2)
The development of an earth abundant, low‐cost, and energy‐efficient electrocatalyst with robust adhesion is highly essential for the generation of hydrogen fuel. Herein, the outstanding overall water splitting performance of a CuCo2O4 catalyst which is fabricated using a hydrothermal process is reported. The performance optimization is done through engineering the surface structure and size of the CuCo2O4 catalyst, without altering its chemical composition and crystallinity. Different solvents used in the hydrothermal growth tune the morphology of CuCo2O4 from porous 2‐dimensional nanosheets through cubes and grains to agglomerated spheres. An optimized 2‐dimensional nanosheet CuCo2O4 catalyst exhibits superior electrochemical performance for both hydrogen evolution reaction and oxygen evolution reaction, achieving the smallest overpotential of 115 and 290 mV versus a reversible hydrogen electrode, respectively, at 10 mA cm−2 with excellent long‐term stability under an alkaline electrolyte medium (1.0 m KOH). This highly stable and electrochemically active bifunctional electrocatalyst can deliver a cell voltage of 1.64 V at 10 mA cm−2 under alkaline condition. Moreover, the correlation between electrochemical catalytic activity with solvent viscosity is manifested in the present study, which reveals that a change in morphologies causes the catalytically active surface area to vary and influences the intrinsic reaction kinetics. 相似文献
45.
With the growing number of malware, malware analysis technologies need to be advanced continuously. Malware authors use various packing techniques to hide their code from malware detection tools and techniques. The packing techniques are generally used to compress and encrypt executable code in executable files, and the unpacking code is usually embedded in the executable files. Therefore, packed executable files can be executed by itself, and the information associated with packing can be used to analyze and detect malware. Since different packing tools will generate different packed executable files, packing tools can be identified by analyzing packed executable files, and packer identification can reduce malware‐analyzing overheads, and the executable files can even be unpacked. However, most previous studies focused on packing detection using signatures of unpacking code, and these approaches can be avoided by placing unpacking code in other locations or by distributing unpacking code in multiple locations. In this paper, we propose a new packer identification method by analyzing only code sections to extract features of malware generated by different packing tools. Experimental results show that our approach can identify different packing tools with the accuracy of 91.6% on average. Considering packer identification is the harder problem than packing detection, we argue that our approach can contribute to reducing overheads of malware analysis. 相似文献
46.
Yeon Sik Choi Jahyun Koo Young Joong Lee Geumbee Lee Raudel Avila Hanze Ying Jonathan Reeder Leonhard Hambitzer Kyungtaek Im Jungwon Kim Kyung‐Mi Lee Jianjun Cheng Yonggang Huang Seung‐Kyun Kang John A. Rogers 《Advanced functional materials》2020,30(31)
Bioresorbable electronic systems represent an emerging class of technology of interest due to their ability to dissolve, chemically degrade, disintegrate, and/or otherwise physically disappear harmlessly in biological environments, as the basis for temporary implants that avoid the need for secondary surgical extraction procedures. Polyanhydride‐based polymers can serve as hydrophobic encapsulation layers for such systems, as a subset of the broader field of transient electronics, where biodegradation eventually occurs by chain scission. Systematic experimental studies that involve immersion in phosphate‐buffered saline solution at various pH values and/or temperatures demonstrate that dissolution occurs through a surface erosion mechanism, with little swelling. The mechanical properties of this polymer are well suited for use in soft, flexible devices, where integration can occur through a mold‐based photopolymerization technique. Studies of the dependence of the polymer properties on monomer compositions and the rates of permeation on coating thicknesses reveal some of the underlying effects. Simple demonstrations illustrate the ability to sustain operation of underlying biodegradable electronic systems for durations between a few hours to a week during complete immersion in aqueous solutions that approximate physiological conditions. Systematic chemical, physical, and in vivo biological studies in animal models reveal no signs of toxicity or other adverse biological responses. 相似文献
47.
Ji-Hyeok Huh Kwangjin Kim Eunji Im Jaewon Lee YongDeok Cho Seungwoo Lee 《Advanced materials (Deerfield Beach, Fla.)》2020,32(51):2001806
The scaling down of meta-atoms or metamolecules (collectively denoted as metaunits) is a long-lasting issue from the time when the concept of metamaterials was first suggested. According to the effective medium theory, which is the foundational concept of metamaterials, the structural sizes of meta-units should be much smaller than the working wavelengths (e.g., << 1/5 wavelength). At relatively low frequency regimes (e.g., microwave and terahertz), the conventional monolithic lithography can readily address the materialization of metamaterials. However, it is still challenging to fabricate optical metamaterials (metamaterials working at optical frequencies such as the visible and near-infrared regimes) through the lithographic approaches. This serves as the rationale for using colloidal self-assembly as a strategy for the realization of optical metamaterials. Colloidal self-assembly can address various critical issues associated with the materialization of optical metamaterials, such as achieving nanogaps over a large area, increasing true 3D structural complexities, and cost-effective processing, which all are difficult to attain through monolithic lithography. Nevertheless, colloidal self-assembly is still a toolset underutilized by optical engineers. Here, the design principle of the colloidally self-assembled optical metamaterials exhibiting unnatural refractions, the practical challenge of relevant experiments, and the future opportunities are critically reviewed. 相似文献
48.
Su‐Kyo Jung Jin Hyuck Heo Byeong M. Oh Jong Bum Lee Sung‐Ha Park Woojin Yoon Yunmi Song Hoseop Yun Jong H. Kim Sang Hyuk Im O‐Pil Kwon 《Advanced functional materials》2020,30(13)
A series of chiral stereoisomers of electron transporting materials with two chiral substituents is rationally designed and synthesized, and the influence of stereoisomerism on their physical and electronic properties is investigated to demonstrate highly efficient and stable perovskite solar cells (PSCs). Compared to mesomeric naphthalene diimide (NDI) derivatives, which have heterochiral side groups with centrosymmetric molecular packing of symmetric‐shaped conformers in the crystalline state, enantiomeric NDI derivatives have homochiral side groups that exhibit non‐centrosymmetric molecular packing of asymmetric‐shaped conformers in the crystalline state and exhibit better solution processability based on one order of magnitude higher solubility. A similar trend is observed in different rylene diimide stereoisomers based on larger semiconducting core perylene diimide. The PSCs based on NDI enantiomers with good film‐forming ability and a very high lowest phase transition temperature (Tlowest) of 321 °C exhibit a high and uniform average power conversion efficiency (PCE) of 19.067 ± 0.654%. These PSCs also have a high temporal device stability, with less than 10% degradation of the PCE at 100 °C for 1000 h without encapsulation. Therefore, chiral stereoisomer engineering of charge transporting materials is a potential approach to achieve high solution processability, excellent performance, and significant temporal stability in organic electronic devices. 相似文献
49.
Jihoon Kim Lauren F. Sestito Sooseok Im Won Jong Kim Susan N. Thomas 《Advanced functional materials》2020,30(16)
Despite the approval of oncolytic virus (OV) therapy for advanced melanoma, its intrinsic limitations that include the risk of persistent viral infection and cost‐intensive manufacturing motivate the development of analogous approaches that are free from the disadvantages of virus‐based therapies. Herein, reported is a nanoassembly comprised of multivalent host–guest interactions between polymerized paclitaxel (pPTX) and nitric oxide‐incorporated polymerized β‐cyclodextrin (pCD‐pSNO) that through its bioactive components and when used locoregionally recapitulates the therapeutic effects of OV. The resultant pPTX/pCD‐pSNO exhibits significantly enhanced cytotoxicity, immunogenic cell death, dendritic cell (DC) activation, and T cell expansion in vitro compared to free agents alone or in combination. In vivo, intratumoral administration of pPTX/pCD‐pSNO results in activation and expansion of DCs systemically, but with a corresponding expansion of myeloid‐derived suppressor cells and suppression of CD8+ T cell expansion. When combined with antibody targeting cytotoxic T lymphocyte antigen‐4 that blunts this molecule's signaling effects on T cells, intratumoral pPTX/pCD‐pSNO treatment elicits potent anticancer effects that significantly prolong animal survival. This formulation thus leverages the chemo‐ and immunotherapeutic synergies of PTX and nitric oxide and suggests the potential for virus‐free nanoformulations to mimic the therapeutic action and benefits of OVs. 相似文献
50.
Ingyun Chung Sunyoung Im Maenghyo Cho 《International journal for numerical methods in engineering》2021,122(1):5-24
Numerical analysis of the hyperelastic behavior of polymer materials has drawn significant interest from within the field of mechanical engineering. Currently, hyperelastic models based on the energy density function, such as the Neo-Hookean, Mooney-Rivlin, and Ogden models, are used to investigate the hyperelastic responses of materials. Conventionally, constants relating to materials were determined from experimental data by using global least-squares fitting. However, formulating a constitutive equation to capture the complex behavior of hyperelastic materials was difficult owing to the limitations of the analytical model and experimental data. This study addresses these limitations by using a system of neural networks (NNs) to design a data-driven surrogate model without a specific function formula, and employs molecular dynamics (MD) simulations to calculate the massive amount of combined loading data of hyperelastic materials. Thus, MD simulations were used to propose an NN constitutive model for hyperelasticity to derive the constitutive equation to model the complex hyperelastic response. In addition, the probability distributions of the numerical solutions of hyperelasticity are used to characterize the uncertainty of the MD models. These statistical finite element results not only present numerical results with reliability ranges but also scattered distributions of the solution obtained from the MD-based probability distributions. 相似文献