全文获取类型
收费全文 | 2803篇 |
免费 | 142篇 |
国内免费 | 86篇 |
专业分类
电工技术 | 55篇 |
技术理论 | 1篇 |
综合类 | 397篇 |
化学工业 | 252篇 |
金属工艺 | 70篇 |
机械仪表 | 250篇 |
建筑科学 | 351篇 |
矿业工程 | 46篇 |
能源动力 | 82篇 |
轻工业 | 65篇 |
水利工程 | 26篇 |
石油天然气 | 63篇 |
武器工业 | 7篇 |
无线电 | 171篇 |
一般工业技术 | 253篇 |
冶金工业 | 63篇 |
原子能技术 | 11篇 |
自动化技术 | 868篇 |
出版年
2024年 | 1篇 |
2023年 | 28篇 |
2022年 | 27篇 |
2021年 | 49篇 |
2020年 | 43篇 |
2019年 | 43篇 |
2018年 | 44篇 |
2017年 | 61篇 |
2016年 | 102篇 |
2015年 | 64篇 |
2014年 | 159篇 |
2013年 | 222篇 |
2012年 | 145篇 |
2011年 | 220篇 |
2010年 | 164篇 |
2009年 | 148篇 |
2008年 | 168篇 |
2007年 | 180篇 |
2006年 | 172篇 |
2005年 | 128篇 |
2004年 | 127篇 |
2003年 | 107篇 |
2002年 | 95篇 |
2001年 | 60篇 |
2000年 | 74篇 |
1999年 | 62篇 |
1998年 | 52篇 |
1997年 | 54篇 |
1996年 | 44篇 |
1995年 | 34篇 |
1994年 | 37篇 |
1993年 | 30篇 |
1992年 | 12篇 |
1991年 | 20篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1980年 | 4篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有3031条查询结果,搜索用时 234 毫秒
1.
《Advanced Powder Technology》2022,33(12):103879
Heat transfer within ceramic feedstock powders is still unclear, which impedes optimization of the thermal and mechanical properties of the thermal sprayed coatings. The microspheres (yttria-stabilized zirconia YSZ and lanthanum zirconate LZO) were prepared via the electro-spraying assisted phase inversion method (ESP). The thermal properties of the two ESP microspheres and a commercial hollow spherical powder (HOSP) were investigated by using theoretical, experimental, and simulation methods. Thermal conductivity of the single microsphere was estimated via a novel nest model that was derived from the Maxwell-Eucken 1 and the EMT model. Thermal conductivity of a single YSZ/LZO-ESP microsphere prepared at 1100–1200 °C was within 0.36–0.75 W/m K, which was ~ 20 % lower than that of a single YSZ-HOSP microsphere with a similar porosity. Heat flux simulation showed that high tortuosity around the multi-scaled voids of the ESP microsphere led to a more efficient decrease in thermal conductivity compared with total porosity. 相似文献
2.
Wenjia Jing Baoqiang Hou Jinxiao Wang Qiang Zhi Jianfeng Yang Bo Wang 《Journal of the American Ceramic Society》2022,105(5):3141-3146
Photocatalysts often show excellent performances on the basis of their surface state of exposed faces with high reactivity, but unfortunately surfaces of this type are usually concealed into the interior of crystals for their high surface energy. We report here a possibility that for fluorine-terminated surfaces of monoclinic ZrO2, these higher-energy surfaces could be retained and exposed. Urchin-like ZrO2 hollow microspheres (UZHS) composed of nanoribbons with exposed (010) facets are obtained through a fluoride mediately solvothermal method. We prove the stabilization effect of fluorine adsorption on (010) facets by density functional theory calculations. More interestingly, UZHS exhibit tunable photocatalytic selectivity in dye degradation. The fluorinated UZHS exhibit good performances both on decomposing Congo red (CR) and methylene blue, while the surface-modified UZHS by calcination only favor decomposition of CR. 相似文献
3.
This research builds on the Theory of Planned Behavior (TPB) by proposing two additional constructs: warm glow and self-expressive benefits which could further drive consumer attitude and purchase intentions in the context of organic food consumption. We employed structural equation modelling (SEM) technique with Smart PLS 3.0 (Partial Least Squares) for the analysis of the hypothesised relationships between these psychological factors and the constructs of the Theory of Planned Behavior (TPB). The theoretical model was tested with samples from India (n = 471) and the USA (n = 440) collected using Amazon’s Mechanical Turk (M Turk). Results confirmed the importance of warm glow and self-expressive benefits in organic consumerism in both markets. The study makes an important contribution in adding these two constructs to the TPB and then suggests practical tips to policy makers. 相似文献
4.
《Mechatronics》2015
Collaboration has been found in previous studies on the design of assembly lines to be a useful mechanism. In this study, the focus is on a collaborative assembly (CA) framework, inspired by the design principles of CCT, the Collaborative Control Theory, to improve balanceability and flexibility of assembly lines through tool sharing (TS) among idle and bottleneck workstations. TS is widely practiced in advanced assembly facilities to reduce cost and improve consistency and standardization in assembly and in assembly-and-test utilities, relying often on real time control. The framework developed here addresses the systems design aspect of Mechatronics, covering the planning, execution, and control mechanisms. Planning includes assembly line balancing (ALB) and initial TS decisions, made continually by solving a bi-objective mixed-integer program (BOMIP). A collaborative multi-agent system (CMAS) enhanced with a TS-best matching (BM) protocol is developed to execute the plan, control the process, and modify the TS decisions, considering dynamic changes in the system’s operations. Experiments show that the new CA framework significantly outperforms classic approaches (i.e., ALB without TS-BM) in terms of cycle time, utilization of tools, and balanceability. In addition, the control mechanism is proven to augment the line’s flexibility against the inherent uncertainties of assembly processes, compared to the previously developed static CA frameworks. 相似文献
5.
Jiji Abraham Krishnan Sidhardhan Sisanth Ajesh Kulamamvila Zachariah Hanna Joseph Mariya Soney C. George Nandakumar Kalarikkal Sabu Thomas 《应用聚合物科学杂志》2020,137(46):49429
Obtaining strong interfacial interaction between filler and polymer matrix is very crucial for the fabrication of polymer nanocomposites with superior performance. Present study is aimed to fabricate high performance styrene butadiene rubber (SBR) nanocomposites with imidazolium type ionic liquid modified multiwalled carbon nanotube (MWCNT). Ionic liquid facilitates the dispersion of MWCNT in rubber matrix and it is obvious from transmission electron microscopy images. Diffusion of toluene through SBR nanocomposite membranes has been investigated as a function of surface modified MWCNT (f-MWCNT) content to analyze the chain dynamics and filler-polymer interactions. O2 gas barrier effect of nanocomposites with special reference to the filler loading is explored. The substantial improvement in the barrier effect in presence of filler interpreted on the grounds of a theoretical model describing permeability of heterogeneous systems. Finally solvent sensing characteristics of prepared nanocomposites are also analyzed and it is observed that prepared nanocomposites can be used as a flexible solvent sensor. 相似文献
6.
7.
Information systems, like biological systems, are susceptible to external perturbations. Similar to flora and fauna in a biome, species of data can be classified within a dataphora. While entropic properties and data geometries can be used to describe local species of data within a dataphora, they are not designed to describe the global properties of an information system or evaluate its stability. Ecologists have used Information Theories to describe macro-level properties of biological ecosystems and statistical tools to evaluate biological systems. This research leverages an ecological perspective to model information systems as a living system. Our findings support the theory of dataphoric ascendancy with Wikipedia having a Diversity Index value of 0.68, within the range of 0.65 and 0.80 that indicates a balanced state. We further support our findings with additional evaluations of other ecosystems including the predicted collapse of the information service known as the Digital Universe. This research allows for an information system’s stability to be (a) characterized and (b) predicted using ecological measures specific to the diversity of data within the ecosystem. 相似文献
8.
The synergistic effects of using several supplementary cementitious materials (SCMs), such as Blast Furnace Slags plus Limestone Filler or Fly Ashes, depend on the OPC composition. When using an OPC which is poor in C3A and alkalis in ternary formulations, a similar initial strength gain to that of a plain OPC is detected and at longer hydration ages, the formation of monocarboaluminate, hemicarbonate and hydrotalcite instead of monosulphate can be seen. If an OPC with a higher C3A content and alkalis is used with SCMs, the higher availability of Al causes the early formation of monocarboaluminate and a lower initial strength gain. At longer hydration times, in ternary blends with both OPCs, the mechanical strengths are higher and the C-S-H gels formed are richer in Al and poorer in C/S ratio with a subsequent lowering of the alkali content in the pore solution when compared to that in plain OPC. 相似文献
9.
地质环境合理开发利用集对论准则 总被引:2,自引:0,他引:2
资源与环境是当今社会面临的两大问题,是影响可持续发展的重要因素。地质环境具有资源与灾害的双重属性,不合理的开发利用将引发环境负效应,其影响具有扩散性与延滞性。借鉴集对论基本原理与方法,对城市化进程中地质环境的合理开发利用提出总体思路及其具体途径。 相似文献
10.
成本管理是涉及煤炭企业各部门的一项综合性管理工作,是整个企业管理的重要组成部分。介绍了成本的概念及内容,成本管理的内容及要求,提高降低的办法和途径。 相似文献