全文获取类型
收费全文 | 2857篇 |
免费 | 118篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 35篇 |
综合类 | 6篇 |
化学工业 | 654篇 |
金属工艺 | 93篇 |
机械仪表 | 74篇 |
建筑科学 | 69篇 |
矿业工程 | 4篇 |
能源动力 | 179篇 |
轻工业 | 210篇 |
水利工程 | 24篇 |
石油天然气 | 5篇 |
无线电 | 290篇 |
一般工业技术 | 685篇 |
冶金工业 | 250篇 |
原子能技术 | 10篇 |
自动化技术 | 397篇 |
出版年
2024年 | 13篇 |
2023年 | 48篇 |
2022年 | 81篇 |
2021年 | 140篇 |
2020年 | 92篇 |
2019年 | 101篇 |
2018年 | 134篇 |
2017年 | 116篇 |
2016年 | 89篇 |
2015年 | 68篇 |
2014年 | 104篇 |
2013年 | 221篇 |
2012年 | 141篇 |
2011年 | 170篇 |
2010年 | 114篇 |
2009年 | 130篇 |
2008年 | 113篇 |
2007年 | 106篇 |
2006年 | 75篇 |
2005年 | 67篇 |
2004年 | 58篇 |
2003年 | 56篇 |
2002年 | 45篇 |
2001年 | 33篇 |
2000年 | 37篇 |
1999年 | 34篇 |
1998年 | 39篇 |
1997年 | 39篇 |
1996年 | 46篇 |
1995年 | 47篇 |
1994年 | 42篇 |
1993年 | 36篇 |
1992年 | 35篇 |
1991年 | 26篇 |
1990年 | 14篇 |
1989年 | 20篇 |
1988年 | 24篇 |
1987年 | 22篇 |
1986年 | 21篇 |
1985年 | 18篇 |
1984年 | 24篇 |
1983年 | 26篇 |
1982年 | 27篇 |
1981年 | 20篇 |
1980年 | 16篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1976年 | 20篇 |
1975年 | 3篇 |
1971年 | 3篇 |
排序方式: 共有2985条查询结果,搜索用时 15 毫秒
31.
Nagavarapu Sarat Chandra Vachhani Leena Sinha Arpita Buriuly Somnath 《International Journal of Control, Automation and Systems》2021,19(1):491-504
International Journal of Control, Automation and Systems - The system of multiple agents working in coordination for a given task has several advantages on faster completion, fault-tolerance, etc.... 相似文献
32.
Neetu Bansal Mukul Gupta Bhaskar Chandra Mohanty Kulvir Singh 《Journal of the American Ceramic Society》2021,104(2):851-859
The presence of alkali ions has reportedly improved the performance of CIGS/CZTS–based thin-film solar cells. The out-diffusion of the alkali ion, in particular, Na, from the glass substrate offers a facile scalable route of supplying the alkali ions during the growth of the absorber layer. In this work, we demonstrate the diffusion of different alkali ions (Li/Na/K) from composition tuned glasses with intentionally incorporated excess alkali ions into a thin Mo film, typically used as a bottom electrode in solar cells. We also evaluate the physical, mechanical, and thermal properties of the glasses for suitability as a substrate in thin-film deposition. The out-diffusion of alkali ions to the overlayer is found to be critically influenced by the composition and the local structure of the glasses. The Na ions exhibit the highest extent of diffusion among the alkali ions present in glass substrates, while that for the K-ions is the lowest. For the glasses with mixed alkali ions, the presence of Li facilitated the out-diffusion of Na, whereas K ions appear to inhibit the same. Differently with the existing reports, we show that the activation energy and the presence of Ca ions as additional modifiers play a crucial role in the transport mechanism of the ions. In addition, the synthesized glasses exhibit hardness of the order 5-7 GPa, density ~2.55 g cm-3. The glass transition temperature lies between 535 and 580°C and the coefficient of thermal expansion 8.5-10 ppm/K, which is highly suitable for use as substrates in thin-film solar cells. 相似文献
33.
Soubhik De Abhinav Omprakash Fulmali Krishna Chaitanya Nuli Rajesh Kumar Prusty B. Gangadhara Prusty Bankim Chandra Ray 《应用聚合物科学杂志》2021,138(15):50208
In this article, modification of carbon fiber surface by carbon based nanofillers (multi-walled carbon nanotubes [CNT], carbon nanofibers, and multi-layered graphene) has been achieved by electrophoretic deposition technique to improve its interfacial bonding with epoxy matrix, with a target to improve the mechanical performance of carbon fiber reinforced polymer composites. Flexural and short beam shear properties of the composites were studied at extreme temperature conditions; in-situ cryo, room and elevated temperature (−196, 30, and 120°C respectively). Laminate reinforced with CNT grafted carbon fibers exhibited highest delamination resistance with maximum improvement in flexural strength as well as in inter-laminar shear strength (ILSS) among all the carbon fiber reinforced epoxy (CE) composites at all in-situ temperatures. CNT modified CE composite showed increment of 9% in flexural strength and 17.43% in ILSS when compared to that of unmodified CE composite at room temperature (30°C). Thermomechanical properties were investigated using dynamic mechanical analysis. Fractography was also carried out to study different modes of failure of the composites. 相似文献
34.
Natural rubber is one of the most potential electro-active polymers for sensors, actuators, and energy harvesting applications. Enhancing the characteristic properties of polymers by reinforcing with fillers that possess multifunctional attributes have attracted considerable attention. In the present study, barium titanate reinforced natural rubber composite is prepared by using two-roll mill mixing. Afterwards, mechanical, electrical, and electromechanical properties of the composites are extensively analyzed by reinforcing different amounts of barium titanate into the matrix of natural rubber. The fabricated dielectric composite shows excellent properties such as high dielectric constant, low dielectric losses, high dielectric breakdown strength, and extreme stretchability. It is observed that as the filler loading reaches the value of 11 parts per hundred rubber (phr), maximum agglomeration of the particles occurs. Maximum stretchability and highest ratio of dielectric constant to elastic modulus are obtained at 8 phr of barium titanate fillers and at the loading, a maximum actuation strain of 11.24% is achieved. This study provides a simple, economical, and effective method for preparing enhanced mechanical, electrical, and electromechanical properties of natural rubber composites, facilitating the wide applications of dielectric materials as actuators and generators. 相似文献
35.
Soubhik De P.N. Shivangi Saswat Choudhury Abhinav Omprakash Fulmali Bankim Chandra Ray Rajesh Kumar Prusty 《应用聚合物科学杂志》2021,138(42):51231
Carbon fiber reinforced epoxy (CE) composite is ideal for a cryogenic fuel storage tank in space applications due to its unmatched specific strength and modulus. In this article, inter-laminar shear strength (ILSS) of carbon fiber/epoxy (CE) composite is shown to be considerably improved by engineering the interface with carboxyl functionalized multi-walled carbon nanotube (FCNT) using electrophoretic deposition technique. FCNT deposited fibers from different bath concentrations (0.3, 0.5, and 1.0 g/L) were used to fabricate the laminates, which were then tested at room (30°C) and in-situ liquid nitrogen (LN) (−196°C) temperature as well as conditioning for different time durations (0.25, 0.5, 1, 6, and 12 h) followed by immediate RT testing to study the applicability of these engineered materials at the cryogenic environment. A maximum increment in ILSS was noticed at bath concentration of 0.5 g/L, which was ~21% and ~ 17% higher than neat composite at 30°C and − 196°C, respectively. Short-term LN conditioning was found to be detrimental due to developed cryogenic shock, which was further found to be compensated by cryogenic interfacial clamping upon long-term exposure. 相似文献
36.
K. M. N. Prasanna A. S. Khanna Ramesh Chandra W. J. Quadakkers 《Oxidation of Metals》1996,46(5-6):465-480
Alumina-forming ODS superalloys are excellent oxidation-resistant materials. Their resistance relies upon the establishment of a stable, slow-growing, and adherent -alumina. In the present investigation, these alloys exhibited unstable and relatively less adherent -alumina phase, which increased the oxidation rate in the transient stage and converted into -alumina in the later part of the exposure. The oxide-growth process was found to depend upon various parameters such as temperature, time, and presence of an active elecment in the superalloy. Characterization carried out by XRD, SEM/EDAX, and AES on oxidized ODS and non-ODS alloys demonstrated a significant influence of the active element, Y, on the transformation of - to -alumina. SIMS analysis of two-stage oxidation at 900°C for two different durations evidently showed that the change in the transport process is due to -to--alumina transformation. On the basis of these results, a new and consistent mechanism is proposed to explain the influence of -alumina and its transformation on growth kinetics and the effect of yttrium on the transformation leading to good scale adherence and oxidation resistance. 相似文献
37.
38.
Interest point detection has a wide range of applications, such as image retrieval and object recognition. Given an image, many previous interest point detectors first assign interest strength to each image point using a certain filtering technique, and then apply non-maximum suppression scheme to select a set of interest point candidates. However, we observe that non-maximum suppression tends to over-suppress good candidates for a weakly textured image such as a face image. We propose a new candidate selection scheme that chooses image points whose zero-/first-order intensities can be clustered into two imbalanced classes (in size), as candidates. Our tests of repeatability across image rotations and lighting conditions show the advantage of imbalance oriented selection. We further present a new face recognition application—facial identity representability evaluation—to show the value of imbalance oriented selection. 相似文献
39.
Gopal Chandra Das Seemanti Saha Abhijit Bhowmick Santi P. Maity 《International Journal of Communication Systems》2023,36(5):e5431
An energy harvesting (EH) and cooperative cognitive radio (CR) network (CRN) is studied in this paper where CR users transmit data through a primary user (PU) channel if the channel remains idle, else an optimal number CRs helps in transmission of PU. To achieve the optimum number of CRs (ONCR) involved in cooperation, a novel scheme based on a combination of channel censoring and total error is proposed. The performance of the proposed scheme is investigated under RF harvesting scenario. The EH is dependent on sensing decision and a CR source harvests energy from PU's RF signal. The harvested energy (HE) is split into two parts: One part is used by the CR network (CRN) for its own transmission, and the other part is used for supporting PU. The effect of the energy allocation factor on total throughput is also investigated. New expressions for optimal number of CRs and throughput are developed. The effect of network parameters such as sensing time, censoring threshold, and energy allocation parameter (EAP) on throughput is investigated. Impact of distance between nodes is also studied. 相似文献
40.
Jindal Sumit Kumar Patra Ritayan Banerjee Sayak Paul Arin Kanekal Dadasikandar Kumar Ajay 《Microsystem Technologies》2022,28(7):1653-1661
Microsystem Technologies - Micro-mechanical systems (MEMS) based piezoresistive pressure sensors have significant importance in several pressure sensor devices in real world, i.e., aviation, IoT... 相似文献