全文获取类型
收费全文 | 600篇 |
免费 | 33篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 153篇 |
金属工艺 | 11篇 |
机械仪表 | 12篇 |
建筑科学 | 7篇 |
能源动力 | 45篇 |
轻工业 | 41篇 |
水利工程 | 8篇 |
无线电 | 64篇 |
一般工业技术 | 142篇 |
冶金工业 | 16篇 |
原子能技术 | 6篇 |
自动化技术 | 125篇 |
出版年
2024年 | 4篇 |
2023年 | 8篇 |
2022年 | 15篇 |
2021年 | 33篇 |
2020年 | 31篇 |
2019年 | 29篇 |
2018年 | 31篇 |
2017年 | 32篇 |
2016年 | 20篇 |
2015年 | 19篇 |
2014年 | 34篇 |
2013年 | 54篇 |
2012年 | 46篇 |
2011年 | 36篇 |
2010年 | 38篇 |
2009年 | 31篇 |
2008年 | 35篇 |
2007年 | 35篇 |
2006年 | 19篇 |
2005年 | 14篇 |
2004年 | 13篇 |
2003年 | 7篇 |
2002年 | 4篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有634条查询结果,搜索用时 0 毫秒
1.
2.
A thio sol–gel process for the synthesis of titanium disulfide using titanium alkoxide as the metal source is demonstrated. The alkoxide reacts at room temperature with H2 S to form a precipitate which is a precursor to the sulfide. Through infrared spectroscopy and chemical analysis of the powder and gas chromatographic analysis of the liquid byproducts of the reaction, it is shown that a partially sulfidized alkoxide precursor forms through the displacement of alkoxy groups from the alkoxide by sulfur-bearing thiol groups. This thiolysis reaction is very similar to that which occurs in the case of sol–gel reactions to form oxides. The alkoxy–thiol species then undergo condensation–polymerization by the liberation of H2 S. When it is heat-treated in H2 S, this precursor transforms to TiS2 at ∼700°C. Systematic heat treatments have been performed and the formation of TiS2 has been observed using X-ray diffractometry. The change in the morphology has also been studied using scanning electron microscopy. 相似文献
3.
The synthesis of thiophene-containing second (G2) and third generation (G3) dendronized macromonomers with methacrylate polymerizable units as well as their corresponding dendronized polymers is reported. The dendrons are prepared from branched thiophene oligomers and are decorated with straight alkyl chains for solubility reasons. The polymerization reactions were done with AIBN as initiator and the polymers were characterized by NMR spectroscopy, elemental analysis and GPC. Molar masses are in the range of 2.2-5.4 × 105 g mol−1 (G2) and 1.3-3.0 × 104 g mol−1 (G3) for different runs. These polymers are investigated by cyclic voltammetry and optical spectroscopy. 相似文献
4.
Juneja Mamta Saini Sumindar Kaur Gupta Jatin Garg Poojita Thakur Niharika Sharma Aviral Mehta Manan Jindal Prashant 《Multimedia Tools and Applications》2021,80(19):29199-29249
Multimedia Tools and Applications - Prostate cancer (PCa) has become the second most dreadful cancer in men after lung cancer. Traditional approaches used for treatment of PCa were manual, time... 相似文献
5.
6.
For a non-idealized machine tool, each point in the workspace is associated with a tool point positioning error vector. If this error map can be determined, then it is possible to substantially improve the positioning performance of the machine by introducing suitable compensation into the control loop. This paper explores the possibility of using an artifical neural network (ANN) to compute this mapping. The training set for the ANN is obtained by mounting a physical artifact whose dimensions are precisely known in the machine's workspace. The machine, equipped with a touch trigger probe, measures the positions of features on the artifact. The difference between the machine reading and the known dimension is the machine error at that point in the workspace. Using standard modeling techniques, the kinematic error model for a CNC turning center was developed. This model was parameterized by measurement of the parametric error functions using a laser interferometer, electronic levels and a precision square. The kinematic model was then used to simulate the artifact-measuring process and develop the ANN training set. The effect of changing artifact geometry was explored and a machining operation was simulated using the ANN output to provide compensation. The results show that the ANN is capable of learning the error map of a real machine, and that ANN-based compensation can significantly reduce part-dimensional errors. 相似文献
7.
This research paper aims to determine the genetic origin of the chemical elements in groundwater. It deals with the results of physicochemical parameters, to evaluate the hydro-geochemistry of groundwater in rural-urban fringe of district Bareilly, India. Pre- and post-monsoon sampling has been carried out, which reveals inter-seasonal variability effect on the hydro-geochemical processes. Geochemical modeling especially computation of saturation index was undertaken using the WATEQ4F model. Majority of samples fall in the category of undersaturation, which further suggests that groundwater still has potential to dissolve more minerals. Chemical categorizations of groundwater samples were performed with the help of the Aquachem model. Grouping of groundwater on the Piper diagram reveals a common composition and origin. In most of the area, water facies is of Ca(2+)-HCO(3)(-) type in both the seasons. It also indicates that in pre-monsoon, ion exchange is the dominant process, whereas in post-monsoon, both ion exchanges as well as reverse ion exchanges are reported in the groundwater of the study area. 相似文献
8.
The study explores the chemical profile, antimicrobial and antioxidant activity of Boswellia carterii essential oil (EO). The EO significantly inhibited growth and aflatoxin production by the food borne toxigenic strain of Aspergillus flavus at 1.75 μl/ml and 1.25 μl/ml respectively. It exhibited broad fungitoxic spectrum against 12 food borne moulds and also showed strong antioxidant activity, IC50 value and % inhibition of linoleic acid peroxidation being 0.64 μl/ml and 51.68% respectively. The antifungal action of EO was observed in terms of reduction in ergosterol content of plasma membrane of A. flavus. As fumigant in food system in storage containers, the EO provided 65.38% protection against fungal deterioration of Piper nigrum. GC–MS results revealed 31 components of EO. The chemically characterized B. carterii EO may thus be recommended as plant based preservative in view of its antifungal, antiaflatoxigenic, antioxidant activity and efficacy in food system. 相似文献
9.
Merits of using advanced oxidation processes such as sonolysis and photocatalysis as well as a combination of the two have been explored using model herbicides such as 2,4-dichlorophenoxy acetic acid and 2,4-dichlorophenoxypropionic acid and the chlorinated phenols 2,4-dichlorophenol and 2,4,6-trichlorophenol. Whereas sonolysis is quite effective in the initial degradation of chlorinated aromatic molecules, complete mineralization is difficult to achieve. Photocatalysis is selective toward the degradation of polar compounds but causes the build up of undesirable chemical intermediates. In contrast to sonolytic degradation, photocatalysis is very effective toward achieving complete mineralization. By simultaneously carrying out high-frequency sonolysis and photocatalysis we have succeeded in achieving faster and complete mineralization with no build up of toxic intermediates even at very low catalyst loadings. The synergy of combining the two advanced oxidation processes is discussed. 相似文献
10.
Prashant Doshi Yifeng Zeng Qiongyu Chen 《Autonomous Agents and Multi-Agent Systems》2009,18(3):376-416
We develop new graphical representations for the problem of sequential decision making in partially observable multiagent environments, as formalized by interactive partially observable Markov decision processes (I-POMDPs). The graphical models
called interactive influence diagrams (I-IDs) and their dynamic counterparts, interactive dynamic influence diagrams (I-DIDs), seek to explicitly model the structure that is often present in real-world problems by decomposing the situation into chance
and decision variables, and the dependencies between the variables. I-DIDs generalize DIDs, which may be viewed as graphical
representations of POMDPs, to multiagent settings in the same way that I-POMDPs generalize POMDPs. I-DIDs may be used to compute
the policy of an agent given its belief as the agent acts and observes in a setting that is populated by other interacting
agents. Using several examples, we show how I-IDs and I-DIDs may be applied and demonstrate their usefulness. We also show
how the models may be solved using the standard algorithms that are applicable to DIDs. Solving I-DIDs exactly involves knowing
the solutions of possible models of the other agents. The space of models grows exponentially with the number of time steps.
We present a method of solving I-DIDs approximately by limiting the number of other agents’ candidate models at each time
step to a constant. We do this by clustering models that are likely to be behaviorally equivalent and selecting a representative
set from the clusters. We discuss the error bound of the approximation technique and demonstrate its empirical performance. 相似文献