全文获取类型
收费全文 | 569篇 |
免费 | 31篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 136篇 |
金属工艺 | 9篇 |
机械仪表 | 8篇 |
建筑科学 | 20篇 |
矿业工程 | 2篇 |
能源动力 | 25篇 |
轻工业 | 87篇 |
水利工程 | 6篇 |
无线电 | 35篇 |
一般工业技术 | 89篇 |
冶金工业 | 98篇 |
原子能技术 | 1篇 |
自动化技术 | 78篇 |
出版年
2022年 | 15篇 |
2021年 | 20篇 |
2020年 | 9篇 |
2019年 | 10篇 |
2018年 | 20篇 |
2017年 | 11篇 |
2016年 | 15篇 |
2015年 | 16篇 |
2014年 | 24篇 |
2013年 | 32篇 |
2012年 | 28篇 |
2011年 | 37篇 |
2010年 | 29篇 |
2009年 | 21篇 |
2008年 | 26篇 |
2007年 | 24篇 |
2006年 | 18篇 |
2005年 | 23篇 |
2004年 | 12篇 |
2003年 | 13篇 |
2002年 | 9篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 14篇 |
1998年 | 26篇 |
1997年 | 23篇 |
1996年 | 18篇 |
1995年 | 13篇 |
1994年 | 15篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 6篇 |
1972年 | 1篇 |
1970年 | 2篇 |
1964年 | 1篇 |
1956年 | 1篇 |
1934年 | 1篇 |
排序方式: 共有600条查询结果,搜索用时 0 毫秒
1.
DV Matei F Pascale A Clemente F Della Corte D Pucello F Grassetti 《Canadian Metallurgical Quarterly》1996,20(3):302-306
Since in vitro experiments had excluded interactions between Fe-gluconate (Fe-gluc) and magnesium-L-aspartate hydrochloride (MAH) in aqueous solutions the present in vivo studies seemed to be justified. Animal studies: Rats were kept on magnesium-(Mg)- and iron-(Fe)- sufficient and deficient diets. The intragastral administration of Fe-gluc significantly increased plasma Fe after 3 h, either given alone, or in combination with MAH (inducing hypermagnesemia). Same results were obtained when fortified diets were offered to Fe/Mg-deficient animals. Human studies: The combination of Fe-gluc (2 x 50 mg Fe per day, per os) plus MAH (2 x 7.5 mmol Mg per day, p.o.) was well tolerated by healthy volunteers. Single dose experiments revealed that Fe-gluc alone and in combination with MAH increased plasma Fe levels during 3 h to the same extent. Two groups of pregnant women with moderately reduced hemoglobin levels either received Fe-gluc (out-patients) or its combination with MAH (at least temporarily hospitalised because of preterm labor). Treatments were well tolerated. Hemoglobin levels did not further decrease, as expected without Fe supplements, during the course of pregnancy, thus indicating the therapeutic availability of the electrolytes in both study groups. Progesterone-induced constipation is frequently observed during pregnancy; hence stool softening reported by 50% of the women receiving Fe-gluc plus MAH (versus 33% in the Fe-gluc group) can be regarded as desirable effect. It is concluded that MAH does not interfere with the enteral absorption of Fe-gluc when both electrolytes are orally administered together. Taking both electrolytes together instead of 2 to 3 h apart from each other, as actually recommended, means a less complicated dosage regimen and probably improves compliance. 相似文献
2.
A. Ritacco R. Adam A. Adane P. Ade P. André A. Beelen B. Belier A. Benoît A. Bideaud N. Billot O. Bourrion M. Calvo A. Catalano G. Coiffard B. Comis A. D’Addabbo F.-X. Désert S. Doyle J. Goupy C. Kramer S. Leclercq J. F. Macías-Pérez J. Martino P. Mauskopf A. Maury F. Mayet A. Monfardini F. Pajot E. Pascale L. Perotto G. Pisano N. Ponthieu M. Rebolo-Iglesias V. Revéret L. Rodriguez G. Savini K. Schuster A. Sievers C. Thum S. Triqueneaux C. Tucker R. Zylka 《Journal of Low Temperature Physics》2016,184(3-4):724-732
3.
Daniel Cosmin Porumbel Jin-Kao Hao Pascale Kuntz 《Computers & Operations Research》2010,37(4):769-778
We present a search space analysis and its application in improving local search algorithms for the graph coloring problem. Using a classical distance measure between colorings, we introduce the following clustering hypothesis: the high quality solutions are not randomly scattered in the search space, but rather grouped in clusters within spheres of specific diameter. We first provide intuitive evidence for this hypothesis by presenting a projection of a large set of local minima in the 3D space. An experimental confirmation is also presented: we introduce two algorithms that exploit the hypothesis by guiding an underlying Tabu Search (TS) process. The first algorithm (TS-Div) uses a learning process to guide the basic TS process toward as-yet-unvisited spheres. The second algorithm (TS-Int) makes deep investigations within a bounded region by organizing it as a tree-like structure of connected spheres. We experimentally demonstrate that if such a region contains a global optimum, TS-Int does not fail in eventually finding it. This pair of algorithms significantly outperforms the underlying basic TS algorithm; it can even improve some of the best-known solutions ever reported in the literature (e.g. for dsjc1000.9). 相似文献
4.
This study examined the implementation of imaging technology into two public sector organizations in the Midwest in the USA. The aims of the study were to analyze the impact of imaging technology on job characteristics and quality of working life, and the influence of the technological change process on employees and organizations. Quantitative and qualitative data were collected using questionnaire surveys and structured and semi-structured interviews. Results showed that imaging users reported more problems with technology and less job satisfaction than employees who were still using their 'old' computer systems. In addition, imaging users in the organization that utilized end user participation in the implementation of their imaging system rated their imaging systems better and reported higher job satisfaction than imaging users in the organization that did not incorporate end user participation in the implementation of the system. The results are discussed in terms of the importance of the technology implementation/ change process, and future directions for research are provided. 相似文献
5.
Jean-Charles Créput Abderrafiaâ Koukam 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2008,12(11):1125-1141
The paper presents an extension of the self- organizing map (SOM) by embedding it into an evolutionary algorithm to solve
the Vehicle Routing Problem (VRP). We call it the memetic SOM. The approach is based on the standard SOM algorithm used as
a main operator in a population based search. This operator is combined with other derived operators specifically dedicated
for greedy insertion moves, a fitness evaluation and a selection operator. The main operators have a similar structure based
on the closest point findings and local moves performed in the plane. They can be interpreted as performing parallels and
massive insertions, simulating the behavior of agents which interact continuously, having localized and limited abilities.
This self-organizing process is intended to allow adaptation to noisy data as well as to confer robustness according to demand
fluctuation. Selection is intended to guide the population based search toward useful solution compromises. We show that the
approach performs better, with respect to solution quality and/or computation time, than other neural network applications
to the VRP presented in the literature. As well, it substantially reduces the gap to classical Operations Research heuristics,
specifically on the large VRP instances with time duration constraint. 相似文献
6.
Chevallier P Turgeon S Sarra-Bournet C Turcotte R Laroche G 《ACS applied materials & interfaces》2011,3(3):750-758
Fog formation on transparent substrates constitutes a major challenge in several optical applications requiring excellent light transmission characteristics. Anti-fog coatings are hydrophilic, enabling water to spread uniformly on the surface rather than form dispersed droplets. Despite the development of several anti-fog coating strategies, the long-term stability, adherence to the underlying substrate, and resistance to cleaning procedures are not yet optimal. We report on a polymer-based anti-fog coating covalently grafted onto glass surfaces by means of a multistep process. Glass substrates were first activated by plasma functionalization to provide amino groups on the surface, resulting in the subsequent covalent bonding of the polymeric layers. The anti-fog coating was then created by the successive spin coating of (poly(ethylene-maleic anhydride) (PEMA) and poly(vinyl alcohol) (PVA) layers. PEMA acted as an interface by covalently reacting with both the glass surface amino functionalities and the PVA hydroxyl groups, while PVA added the necessary surface hydrophilicity to provide anti-fog properties. Each step of the procedure was monitored by XPS, which confirmed the successful grafting of the coating. Coating thickness was evaluated by profilometry, nanoindentation, and UV visible light transmission. The hydrophilic nature of the anti-fog coating was assessed by water contact angle (CA), and its anti-fog efficiency was determined visually and tested quantitatively for the first time using an ASTM standard protocol. Results show that the PEMA/PVA coating not only delayed the initial period required for fog formation but also decreased the rate of light transmission decay. Finally, following a 24 hour immersion in water, these PEMA/PVA coatings remained stable and preserved their anti-fog properties. 相似文献
7.
Jean-Baptiste Domergue Julie Lalande Daniel Beucher Pascale Satour Cyril Abadie Anis M. Limami Guillaume Tcherkez 《International journal of molecular sciences》2022,23(15)
Seed size is often considered to be an important trait for seed quality, i.e., vigour and germination performance. It is believed that seed size reflects the quantity of reserve material and thus the C and N sources available for post-germinative processes. However, mechanisms linking seed size and quality are poorly documented. In particular, specific metabolic changes when seed size varies are not well-known. To gain insight into this aspect, we examined seed size and composition across different accessions of barrel medic (Medicago truncatula Gaertn.) from the genetic core collection. We conducted multi-elemental analyses and isotope measurements, as well as exact mass GC–MS metabolomics. There was a systematic increase in N content (+0.17% N mg−1) and a decrease in H content (–0.14% H mg−1) with seed size, reflecting lower lipid and higher S-poor protein quantity. There was also a decrease in 2H natural abundance (δ2H), due to the lower prevalence of 2H-enriched lipid hydrogen atoms that underwent isotopic exchange with water during seed development. Metabolomics showed that seed size correlates with free amino acid and hexoses content, and anticorrelates with amino acid degradation products, disaccharides, malic acid and free fatty acids. All accessions followed the same trend, with insignificant differences in metabolic properties between them. Our results show that there is no general, proportional increase in metabolite pools with seed size. Seed size appears to be determined by metabolic balance (between sugar and amino acid degradation vs. utilisation for storage), which is in turn likely determined by phloem source metabolite delivery during seed development. 相似文献
8.
I. Dantone L. Fabbri E. Foschi C. Guandalini G. Laurenti I. Lax G. Levi L. Quadrani Ca. Sbarra Cr. Sbarra M. Villa A. Zoccoli M. Zuffa 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,630(1):384
The silicon photomultipliers (SiPM) are adopted in various physical applications, from medical physics to astrophysics, for their advantages in terms of cost and weight with respect to traditional photo detectors. Their low bias voltage supply (about 30 V), hardiness and resistance to magnetic field are ideal characteristics for space application. In the frame of INFN-Irst collaboration, some of them have been developed and produced at FBK (Trento-Italy), and have been characterized in the INFN laboratories of Bologna (DaSiPM2 collaboration).The SiPM can be used in conjunction with fibres and counters in high energy physics experiments. To exploit the SiPM time resolution, a fast amplifier has been studied. The SiPM gain depends critically on temperature and a thermal stabilization is also necessary. The use of a thermoelectric cooler module based on a Peltier cell has been investigated, and the results are shown. 相似文献
9.
10.
Incorporation of process integration into life cycle analysis for the production of biofuels 总被引:1,自引:1,他引:0
Pascale Chouinard-Dussault Laura Bradt José María Ponce-Ortega Mahmoud M. El-Halwagi 《Clean Technologies and Environmental Policy》2011,13(5):673-685
This article presents a new approach for incorporating process-integration tools into life cycle analysis (LCA) for biofuel production. Process synthesis techniques using mass- and energy-integration tools are employed to generate various scenarios for reducing mass and energy consumption in the process. The global implications of these changes and the associated trade-offs are assessed using the LCA tool: GREET. The developed approach enables the consideration of several levels of process integration while tracking the process economics and the reduction of the net greenhouse gas emissions. Several cases of biofuels with different processing technologies have been considered in this study, and the results show that when the process-integration tools are effectively utilized and combined with LCA, better insights are obtained and the net greenhouse gas emissions decrease drastically for different biofuels. 相似文献