全文获取类型
收费全文 | 9012篇 |
免费 | 663篇 |
国内免费 | 14篇 |
专业分类
电工技术 | 128篇 |
综合类 | 2篇 |
化学工业 | 2530篇 |
金属工艺 | 155篇 |
机械仪表 | 279篇 |
建筑科学 | 363篇 |
矿业工程 | 29篇 |
能源动力 | 355篇 |
轻工业 | 1451篇 |
水利工程 | 102篇 |
石油天然气 | 53篇 |
无线电 | 574篇 |
一般工业技术 | 1398篇 |
冶金工业 | 576篇 |
原子能技术 | 69篇 |
自动化技术 | 1625篇 |
出版年
2024年 | 29篇 |
2023年 | 116篇 |
2022年 | 344篇 |
2021年 | 417篇 |
2020年 | 284篇 |
2019年 | 324篇 |
2018年 | 378篇 |
2017年 | 400篇 |
2016年 | 360篇 |
2015年 | 310篇 |
2014年 | 427篇 |
2013年 | 743篇 |
2012年 | 589篇 |
2011年 | 710篇 |
2010年 | 500篇 |
2009年 | 530篇 |
2008年 | 453篇 |
2007年 | 415篇 |
2006年 | 338篇 |
2005年 | 244篇 |
2004年 | 207篇 |
2003年 | 201篇 |
2002年 | 177篇 |
2001年 | 117篇 |
2000年 | 118篇 |
1999年 | 92篇 |
1998年 | 152篇 |
1997年 | 121篇 |
1996年 | 86篇 |
1995年 | 79篇 |
1994年 | 51篇 |
1993年 | 47篇 |
1992年 | 25篇 |
1991年 | 29篇 |
1990年 | 23篇 |
1989年 | 29篇 |
1988年 | 18篇 |
1987年 | 12篇 |
1986年 | 17篇 |
1985年 | 20篇 |
1984年 | 16篇 |
1983年 | 11篇 |
1982年 | 17篇 |
1981年 | 10篇 |
1980年 | 12篇 |
1979年 | 12篇 |
1978年 | 21篇 |
1976年 | 17篇 |
1975年 | 6篇 |
1973年 | 6篇 |
排序方式: 共有9689条查询结果,搜索用时 16 毫秒
41.
Juan Carlos Benítez Carlos A. Giúdice Vicente J. D. Rascio 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1985,35(8):387-394
This paper discusses the bioactivity of antifouling paints based on organotin toxicants, such as tributyltin fluoride (TBTF) and triphenyltin fluoride (TPTF). These compounds were used alone or mixed as the main toxicant in formulations. The use of TPTF or mixtures of TPTF and TBTF, with vinyl binders, led to paints with satisfactory bioactivity during a 24 months immersion period. With the same binders, TBTF alone provided only 12 months of antifouling protection. The correlation coefficients calculated from the fouling attachment values and the rosin content in the binder showed that the bioactivity of the tested formulations depended on the solubility of the toxicant in sea water and on the composition and solubility of the binders. 相似文献
42.
43.
44.
Talita Moreira de Oliveira Nilda de Fátima Ferreira Soares Rodrigo Magela Pereira Kátia de Freitas Fraga 《Packaging Technology and Science》2007,20(2):147-153
Conservation of food products depends on product quality and packaging suitability. The objective of this work was to develop and evaluate the antimicrobial efficiency of natamycin‐incorporated film in the production process of Gorgonzola cheese. It aims to optimize the production process and increase shelf‐life and food safety for the consumer. Films with different concentrations of natamycin were produced and tested in Gorgonzola cheeses to evaluate its efficiency against Penicillium roqueforti on the cheese surface. Films with 2 and 4% natamycin presented satisfactory results for fungus inhibition and the amount of natamycin released to the cheese was below that allowed by the legislation. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
45.
46.
Venezuela's vast natural resource base has largely shaped the nation's economic and energy-use patterns. Major opportunities exist for improving the efficiency of energy use in Venezuela and, consequently, restraining the growth of energy-related carbon emissions. This paper presents a detailed report of one potential development path for Venezuela and estimates the ensuing levels of energy demand and CO2 emissions associated with pursuing this path through the year 2025. The results indicate that by adopting a development strategy that incorporates structural changes in the economy, fuel-switching measures and improved end-use efficiencies, Venezuela can introduce energy efficiency and carbon restraints as part of its economic development process. 相似文献
47.
Francisco J. Collado Eduardo Sevilla Carlos Valcárcel 《American Institute of Chemical Engineers》2002,48(5):1100-1108
New thermodynamic fundamentals for vertical pneumatic conueying are proposed with derivation based strictly on mass conservation and continuum concept. For a 1-D, vertical, steady gas-solid flow, these new mass and energy balances allowed the derivation of a new nondimensional energy factor containing the pressure drop. This energy factor correlated quite well with the difference between the inlet gas velocity and solids terminal velocity, when tested against high-pressure, 15-m-high, vertical pneumatic transport data from Institute of Gas Technology. The energy factor was also checked against atmospheric-pressure data of the 5-m lift line of the Pennsylvania State Uniuersity. The new energy factor covers quite well both the atmospheric- and high-pressure sets of data (923 tests) including two heights, lean- and dense-phase transports, several pipe diameters, broad and narrow particle-size distributions, and different materials. The dissipation terms in gas-solid flow were also clearly identified. 相似文献
48.
In this work, we present a novel process to produce plasticized PVC articles. Plasticized PVC dispersion resin (dry blend) was extruded and poured into a hot mold. The mold was transferred to a rotomolding machine, where the final geometry was obtained. Formulations using commercial PVC suspension resin and three different types of plasticizers were prepared under different processing conditions. The physical appearance of the articles and the tensile properties of the materials were evaluated. 相似文献
49.
Dipl.-Phys. Andreas Neuber M. Sc. Guenther Carlos Krieger Dipl.-Ing. Markus Tacke Prof. Dr.-Ing Johannes Janicka 《Forschung im Ingenieurwesen》1996,62(7-8):188-194
Zusammenfassung Die laserspektroskopischen Me?methoden laserinduzierte Fluoreszenz und spontane Ramanspektroskopie werden eingesetzt zur Messung
der Konzentrationen von Stickoxid, Hydroxyl sowie der chemischen Hauptkomponenten und der Temperatur. Betrachtet wird die
thermische Umsetzung von Wasserstoff mit Luftsauerstoff. Es wird die experimentelle Vorgehensweise und Problematik dargestellt.
Ebenso wird der Weg der Modellierung und Berechnung turbulenter Verbrennungsvorg?nge am konkreten Beispiel skizziert. Die
Annahme chemischen Gleichgewichts stellt sich als ungenügend in der Berechnung der Stickoxid- und Hydroxylkonzentrationen
heraus. Eine deutlich bessere Vorhersage wird durch Einführen einer Reaktionsfortschrittsvariablen für das chemische Modell
erreicht. 相似文献
50.
Crosslinking of tissue-derived biomaterials in 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) 总被引:2,自引:0,他引:2
J. M. Lee H. H. L. Edwards C. A. Pereira S. I. Samii 《Journal of materials science. Materials in medicine》1996,7(9):531-541
In contrast to bifunctional reagents such as glutaraldehyde or polyfunctional reagents such as polyepoxides, carbodiimides belong to the class of zero-length crosslinkers which modify amino acid side-groups to permit crosslink formation, but do not remain as part of that linkage. The authors have compared the effects of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and glutaraldehyde (the de facto industrial standard crosslinker) on the hydrothermal, biochemical, and uniaxial mechanical properties of bovine pericardium. EDC crosslinking was optimized for maximum increase in collagen denaturation temperature using variables of pH, concentration, and ratio of EDC to N-hydroxysuccinimide (NHS): a reagent for formation of activated esters. EDC and glutaraldehyde crosslinked materials were subjected to hydrothermal denaturation tests, biochemical degradation by enzymes (collagenase, trypsin) and CNBr, amino acid analysis for unreacted lysine, and to high strain rate mechanical tests including: large deformation stress-strain studies (0.1 to 10 Hz), stress relaxation experiments (loading time 0.1 s) and small deformation forced vibration (1 and 10 Hz). A protocol for EDC crosslinking was developed which used 1.15% EDC (2:1 EDC:NHS) at pH 5.5 for 24 h. The increase in denaturation temperature for EDC (from 69.7±1.2°C to 86.0±0.3°C) was equivalent to that produced by glutaraldehyde (85.3±0.4°C). Both treatments equivalently increased resistance to collagenase and CNBr degradation; however, after denaturation, the EDC-treated tissue was slightly more resistant to collagenase, and markedly more resistant to trypsin. EDC-treated materials were more extensible and more elastic than glutaraldehyde-treated materials. Despite the differences in crosslinking mechanism, EDC and glutaraldehyde-treated materials are very similar. Subtle but intriguing differences in biochemical structure remain to be investigated. 相似文献