全文获取类型
收费全文 | 905篇 |
免费 | 42篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 20篇 |
综合类 | 1篇 |
化学工业 | 186篇 |
金属工艺 | 48篇 |
机械仪表 | 17篇 |
建筑科学 | 10篇 |
矿业工程 | 2篇 |
能源动力 | 57篇 |
轻工业 | 71篇 |
水利工程 | 8篇 |
石油天然气 | 2篇 |
无线电 | 106篇 |
一般工业技术 | 208篇 |
冶金工业 | 80篇 |
原子能技术 | 6篇 |
自动化技术 | 128篇 |
出版年
2024年 | 4篇 |
2023年 | 23篇 |
2022年 | 22篇 |
2021年 | 39篇 |
2020年 | 32篇 |
2019年 | 31篇 |
2018年 | 33篇 |
2017年 | 46篇 |
2016年 | 48篇 |
2015年 | 29篇 |
2014年 | 35篇 |
2013年 | 70篇 |
2012年 | 54篇 |
2011年 | 61篇 |
2010年 | 42篇 |
2009年 | 35篇 |
2008年 | 54篇 |
2007年 | 34篇 |
2006年 | 32篇 |
2005年 | 16篇 |
2004年 | 16篇 |
2003年 | 19篇 |
2002年 | 11篇 |
2001年 | 8篇 |
2000年 | 9篇 |
1999年 | 5篇 |
1998年 | 17篇 |
1997年 | 21篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 9篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1985年 | 11篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 8篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 7篇 |
1975年 | 4篇 |
1972年 | 1篇 |
1929年 | 1篇 |
排序方式: 共有950条查询结果,搜索用时 0 毫秒
141.
Kaustav Barat S. Sivaprasad Sujoy Kumar Kar Soumitra Tarafder 《Fatigue & Fracture of Engineering Materials & Structures》2019,42(12):2823-2843
The influence of various strain waveforms on the low‐cycle fatigue of IN 718 tested at 650°C has been investigated. The straining paths are accompanied by dwell‐induced creep component(s) or unequal strain distribution in different portions of cycles reducing strength of material. The investigation intends to clarify mainly mechanistic aspects of relaxation‐fatigue interaction. Features of time‐dependent effect induced by nonpeak dwell and the same accompanied by peak dwell, slow unloading from the peak to a lower strain, and different loading and unloading rates are compared in terms of stress amplitude responses, mean stress relaxation, hysteresis loops, life, and damage parameter DC‐F. Softening is common in all the cases, and degree of softening varies linearly with life. The energy‐based life prediction model has been found to work well for the data, and we have introduced energy fraction–based approach to observe simultaneous contribution from both creep and fatigue on life. 相似文献
142.
Lal Kundan Soumya Suddha Mallick Bonamali Pal 《Particulate Science and Technology》2017,35(3):265-276
The existing models to predict the thermal conductivity of nanofluids are based on single particle diameter, whereas, in actual solutions, nanoparticles mostly exist in a cluster form. Experiments are carried out to observe the effects of various surfactants on stability, nanocluster formation, and thermal conductivity of Al2O3–H2O nanofluid, which is found to be improved considerably with SDS surfactant. The prolonged sonication was not adequate to break the clusters of Al2O3 nanoparticles, into an average size of less than 163 nm, indicating the tendency of Al2O3 nanoparticles to remain in the form of clusters instead of individual nanoparticles of primary size of 20 nm. Response surface methodology has been employed to design and optimize the experimental strategy by taking volumetric concentration, temperature, and surfactant amount as the contributing factors. The developed model has been validated against the experimental data and the existing models with an accuracy level of ± 8% in the former case. Analysis reveals about the formation of nanoclusters and enhancement in thermal conductivity. The results confirmed that the model can predict thermal conductivity enhancement with an accuracy level of R square value of the order of 0.9766. 相似文献
143.
Hapipi Nurhidayah Mohd Chen Soo Kien Shaari Abdul Halim Kechik Mohd Mustafa Awang Lim Kean Pah Tan Kar Ban Lee Oon Jew Arvapalli Sai Srikanth Miryala Muralidhar 《Journal of Materials Science: Materials in Electronics》2022,33(14):11269-11270
Journal of Materials Science: Materials in Electronics - 相似文献
144.
Soumya Sarkar Sreetosh Goswami Maxim Trushin Surajit Saha Majid Panahandeh‐Fard Saurav Prakash Sherman Jun Rong Tan Mary Scott Kian Ping Loh Shaffique Adam Sinu Mathew Thirumalai Venkatesan 《Advanced materials (Deerfield Beach, Fla.)》2019,31(41)
The reduced electrical screening in 2D materials provides an ideal platform for realization of exotic quasiparticles, that are robust and whose functionalities can be exploited for future electronic, optoelectronic, and valleytronic applications. Recent examples include an interlayer exciton, where an electron from one layer binds with a hole from another, and a Holstein polaron, formed by an electron dressed by a sea of phonons. Here, a new quasiparticle is reported, “polaronic trion” in a heterostructure of MoS2/SrTiO3 (STO). This emerges as the Fröhlich bound state of the trion in the atomically thin monolayer of MoS2 and the very unique low energy soft phonon mode (≤7 meV, which is temperature and field tunable) in the quantum paraelectric substrate STO, arising below its structural antiferrodistortive (AFD) phase transition temperature. This dressing of the trion with soft phonons manifests in an anomalous temperature dependence of photoluminescence emission leading to a huge enhancement of the trion binding energy (≈70 meV). The soft phonons in STO are sensitive to electric field, which enables field control of the interfacial trion–phonon coupling and resultant polaronic trion binding energy. Polaronic trions could provide a platform to realize quasiparticle‐based tunable optoelectronic applications driven by many body effects. 相似文献
145.
A microstrip patch filtenna inspired by defected ground structure (DGS) is presented in this article. It uses modified split ring resonator and capacitance loaded strip as a radiating element. The presented structure is incorporated with a pair of double U‐shaped DGS (DU‐DGS) to obtain filtering characteristics. The width of DU‐DGS plays a vital role in selecting attenuation poles of the filter as well as for the filtenna circuit. The separation distance between the DU‐DGS also affects the resonant frequency of the structure. Both radiation and filtration can be performed through a single structure, otherwise known as filtenna. The physical size of the proposed filtenna in terms of guided wavelength is 2.465λg × 1.160λg × 0.116λg at 10.8 GHz, and is comparatively less to others reported, so is considered as a superior feature. The presented filtenna possesses impedance bandwidth of 700 and 1800 MHz at 10.8 and 16.6 GHz, which covers standards of X‐ and Ku‐band, respectively. So, this can be referred to as dual band filtenna. The radiation pattern shows omnidirectionality in both E and H planes at resonance. 相似文献
146.
Machine Learning - Rankboost is a well-known algorithm that iteratively creates and aggregates a collection of “weak rankers” to build an effective ranking procedure. Initial work on... 相似文献
147.
Converting quadrilateral meshes to smooth manifolds, guided subdivision offers a way to combine the good highlight line distribution of recent G‐spline constructions with the refinability of subdivision surfaces. This avoids the complex refinement of G‐spline constructions and the poor shape of standard subdivision. Guided subdivision can then be used both to generate the surface and hierarchically compute functions on the surface. Specifically, we present a C2 subdivision algorithm of polynomial degree bi‐6 and a curvature bounded algorithm of degree bi‐5. We prove that the common eigenstructure of this class of subdivision algorithms is determined by their guide and demonstrate that their eigenspectrum (speed of contraction) can be adjusted without harming the shape. For practical implementation, a finite number of subdivision steps can be completed by a high‐quality cap. Near irregular points this allows leveraging standard polynomial tools both for rendering of the surface and for approximately integrating functions on the surface. 相似文献
148.
Gupta Isha Nayak Soumya Ranjan Gupta Sheifali Singh Swati Verma K.D. Gupta Abhishek Prakash Deo 《Multimedia Tools and Applications》2022,81(25):36309-36330
Multimedia Tools and Applications - Breast cancer is one of the widespread reasons of morbidity worldwide that begins in the cells of the tissues of morbidity worldwide in the woman community.... 相似文献
149.
Nabanita Saha S. K. Akbar Ali Sritama Kar Petr Saha Ajit K. Banthia 《应用聚合物科学杂志》2006,102(5):4963-4970
Poly(viny alcohol)–poly(vinyl pyrrolidone) biodegradable polymer blend was modified with aluminosilicate. Sample films containing 5, 10, 15, and 20 wt % filler were prepared by conventional solvent casting technique using glass plates as casting surfaces. The newly developed biodegradable composites are bright red, with magnetic properties due to the presence of iron compounds. Physical, chemical, and biodegradable properties of the films were studied with the conclusion that the presence of aluminosilicate affects the properties of the matrix and enhances biodegradability of the polymer composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4963–4970, 2006 相似文献
150.
Piezoelectric Nylon‐11 Nanowire Arrays Grown by Template Wetting for Vibrational Energy Harvesting Applications 下载免费PDF全文
Anuja Datta Yeon Sik Choi Evie Chalmers Canlin Ou Sohini Kar‐Narayan 《Advanced functional materials》2017,27(2)
Piezoelectric polymers, capable of converting mechanical vibrations into electrical energy, are attractive for use in vibrational energy harvesting due to their flexibility, robustness, ease, and low cost of fabrication. In particular, piezoelectric polymers nanostructures have been found to exhibit higher crystallinity, higher piezoelectric coefficients, and “self‐poling,” as compared to films or bulk. The research in this area has been mainly dominated by polyvinylidene fluoride and its copolymers, which while promising have a limited temperature range of operation due to their low Curie and/or melting temperatures. Here, the authors report the fabrication and properties of vertically aligned and “self‐poled” piezoelectric Nylon‐11 nanowires with a melting temperature of ≈200 °C, grown by a facile and scalable capillary wetting technique. It is shown that a simple nanogenerator comprising as‐grown Nylon‐11 nanowires, embedded in an anodized aluminium oxide (AAO) template, can produce an open‐circuit voltage of 1 V and short‐circuit current of 100 nA, when subjected to small‐amplitude, low‐frequency vibrations. Importantly, the resulting nanogenerator is shown to exhibit excellent fatigue performance and high temperature stability. The work thus offers the possibility of exploiting a previously unexplored low‐cost piezoelectric polymer for nanowire‐based energy harvesting, particularly at temperatures well above room temperature. 相似文献