全文获取类型
收费全文 | 434篇 |
免费 | 22篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 148篇 |
金属工艺 | 22篇 |
机械仪表 | 6篇 |
建筑科学 | 13篇 |
矿业工程 | 1篇 |
能源动力 | 16篇 |
轻工业 | 50篇 |
水利工程 | 4篇 |
石油天然气 | 1篇 |
武器工业 | 1篇 |
无线电 | 40篇 |
一般工业技术 | 77篇 |
冶金工业 | 30篇 |
原子能技术 | 7篇 |
自动化技术 | 32篇 |
出版年
2022年 | 13篇 |
2021年 | 19篇 |
2020年 | 8篇 |
2019年 | 7篇 |
2018年 | 8篇 |
2017年 | 12篇 |
2016年 | 19篇 |
2015年 | 25篇 |
2014年 | 20篇 |
2013年 | 41篇 |
2012年 | 27篇 |
2011年 | 29篇 |
2010年 | 26篇 |
2009年 | 19篇 |
2008年 | 22篇 |
2007年 | 16篇 |
2006年 | 16篇 |
2005年 | 14篇 |
2004年 | 22篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1992年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有457条查询结果,搜索用时 15 毫秒
1.
Jiri Patocka Ran Wu Eugenie Nepovimova Martin Valis Wenda Wu Kamil Kuca 《International journal of molecular sciences》2021,22(4)
Mushroom poisoning has always been a threat to human health. There are a large number of reports about ingestion of poisonous mushrooms every year around the world. It attracts the attention of researchers, especially in the aspects of toxin composition, toxic mechanism and toxin application in poisonous mushroom. Inocybe is a large genus of mushrooms and contains toxic substances including muscarine, psilocybin, psilocin, aeruginascin, lectins and baeocystin. In order to prevent and remedy mushroom poisoning, it is significant to clarify the toxic effects and mechanisms of these bioactive substances. In this review article, we summarize the chemistry, most known toxic effects and mechanisms of major toxic substances in Inocybe mushrooms, especially muscarine, psilocybin and psilocin. Their available toxicity data (different species, different administration routes) published formerly are also summarized. In addition, the treatment and medical application of these toxic substances in Inocybe mushrooms are also discussed. We hope that this review will help understanding of the chemistry and toxicology of Inocybe mushrooms as well as the potential clinical application of its bioactive substances to benefit human beings. 相似文献
2.
3.
4.
The effect of alumina particulates on a thermoplastic matrix is investigated, in particular the effect altering the alumina particle size and morphology has on the mechanical properties. Different grades of alumina are used and two thermoplastic matrices; namely poly(propylene) and poly(ethylene-co-vinyl acetate). Investigations showed that optimum properties were achieved with the alumina of smallest particle size and lowest aspect ratio. Preliminary work has also been performed on the use of silane coupling agents and they have proved effective in increasing the tensile properties of the composites. 相似文献
5.
With the rapid expansion of markets for telecommunications services and equipment, both national and international, one sees an increasing frequency of alliances in which each of two firms seeks to use the other to complete its portfolio strengths. Often this combination enables firms to achieve the product differentiation that seems to be the key to competitive advantage in modern telecommunications markets. This alliance may take the form of a « joint venture », which in the paper includes as limiting cases a subsidiary wholly owned by one firm, a technology licensing arrangement, and direct exporting. The model of such a venture presented here, although simple, is rich enough to illustrate the influence of four types of factors on the negotiations that set up the venture: demand, costs, risk, and regulatory constraints. We characterize the sets of acceptable and efficient arrangements, under various assumptions about exogeneous factors. The partners must choose among these by some form of bargaining. 相似文献
6.
7.
Cynthia Bruckner-Lea Ryan J. Kimmel Jiri Janata John F. T. Conroy Karin Caldwell 《Electrochimica acta》1995,40(18):2897-2904
Octadecanethiol (ODT) and octanethiol (OT) films at the mercury-electrolyte interface are examined using cyclic voltammetry and differential capacitance measurements at a single frequency. A mercury flow-system is used to alter the volume, and therefore, the surface area and surface pressure of the mercury electrode. Manipulation of the mercury electrode's volume enables the introduction and removal of defects in the insulating thiol films. OT and ODT film behavior are contrasted under conditions of expansion and contraction. ODT forms extremely impermeable layers that allow 1000 time less redox probe current than seen on uncoated drops. Expansion of the mercury electrode to increase the electrode surface area produces defects and pinholes in the thiol film. These defects are almost completely removed when the drop is compressed back to its initial surface area. OT also forms insulating films on mercury sessile drops, however these films contain more defects than ODT films. While expansion of an OT-coated mercury drop increases redox probe current, recompression of the drop does not return the film to its initial condition. Pinholes and defects in the OT and ODT films can also be produced by cycling to negative potentials, which produce abrupt stripping peaks. 相似文献
8.
Fuchs E Gruber T Nitschke J Sick B 《IEEE transactions on pattern analysis and machine intelligence》2010,32(12):2232-2245
The paper presents SwiftSeg, a novel technique for online time series segmentation and piecewise polynomial representation. The segmentation approach is based on a least-squares approximation of time series in sliding and/or growing time windows utilizing a basis of orthogonal polynomials. This allows the definition of fast update steps for the approximating polynomial, where the computational effort depends only on the degree of the approximating polynomial and not on the length of the time window. The coefficients of the orthogonal expansion of the approximating polynomial-obtained by means of the update steps-can be interpreted as optimal (in the least-squares sense) estimators for average, slope, curvature, change of curvature, etc., of the signal in the time window considered. These coefficients, as well as the approximation error, may be used in a very intuitive way to define segmentation criteria. The properties of SwiftSeg are evaluated by means of some artificial and real benchmark time series. It is compared to three different offline and online techniques to assess its accuracy and runtime. It is shown that SwiftSeg-which is suitable for many data streaming applications-offers high accuracy at very low computational costs. 相似文献
9.
The different steps of the dehalogenation reaction carried out by LinB on three different substrates have been characterized using a combination of quantum mechanical calculations and molecular dynamics simulations. This has allowed us to obtain information in atomic detail about each step of the reaction mechanism, that is, substrate entrance and achievement of the near-attack conformation, transition state stabilization within the active site, halide stabilization, water molecule activation and subsequent hydrolytic attack on the ester intermediate with formation of alcohol, and finally product release. Importantly, no bias or external forces were applied during the whole procedure so that both intermediates and products were completely free to sample configuration space in order to adapt to the plasticity of the active site and/or search for an exit. Differences in substrate reactivity were found to be correlated with the ease of adopting the near-attack conformation and two different exit pathways were found for product release that do not interfere with substrate entrance. Additional support for the different entry and exit pathways was independently obtained from an examination of the enzyme's normal modes. 相似文献
10.
In the course of the past few years, sonography has become firmly established in clinical practice. The accuracy of the investigations does not only depend on the quality of the equipment used but also to a considerable degree on the standards of investigator training. To reduce the discrepancy between the number and quality of the investigations in the German Federal Republic, the "Kassen?rztliche Vereinigung" has released guidelines requiring the users of sonographic equipment to undergo theoretical and practical training. These guidelines are reviewed and commented. 相似文献