全文获取类型
收费全文 | 2796篇 |
免费 | 49篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 45篇 |
综合类 | 3篇 |
化学工业 | 559篇 |
金属工艺 | 162篇 |
机械仪表 | 71篇 |
建筑科学 | 148篇 |
矿业工程 | 10篇 |
能源动力 | 98篇 |
轻工业 | 226篇 |
水利工程 | 26篇 |
石油天然气 | 62篇 |
武器工业 | 1篇 |
无线电 | 207篇 |
一般工业技术 | 691篇 |
冶金工业 | 215篇 |
原子能技术 | 80篇 |
自动化技术 | 253篇 |
出版年
2022年 | 14篇 |
2021年 | 30篇 |
2020年 | 21篇 |
2019年 | 23篇 |
2018年 | 66篇 |
2017年 | 53篇 |
2016年 | 55篇 |
2015年 | 41篇 |
2014年 | 45篇 |
2013年 | 105篇 |
2012年 | 103篇 |
2011年 | 160篇 |
2010年 | 131篇 |
2009年 | 131篇 |
2008年 | 94篇 |
2007年 | 113篇 |
2006年 | 113篇 |
2005年 | 64篇 |
2004年 | 64篇 |
2003年 | 84篇 |
2002年 | 79篇 |
2001年 | 90篇 |
2000年 | 60篇 |
1999年 | 49篇 |
1998年 | 100篇 |
1997年 | 93篇 |
1996年 | 60篇 |
1995年 | 50篇 |
1994年 | 50篇 |
1993年 | 55篇 |
1992年 | 39篇 |
1991年 | 42篇 |
1990年 | 30篇 |
1989年 | 36篇 |
1988年 | 34篇 |
1987年 | 38篇 |
1986年 | 44篇 |
1985年 | 32篇 |
1984年 | 35篇 |
1983年 | 14篇 |
1982年 | 18篇 |
1981年 | 26篇 |
1980年 | 15篇 |
1979年 | 21篇 |
1978年 | 14篇 |
1977年 | 21篇 |
1976年 | 32篇 |
1975年 | 14篇 |
1974年 | 18篇 |
1973年 | 16篇 |
排序方式: 共有2857条查询结果,搜索用时 15 毫秒
181.
Active Fiber Composites made from piezoelectric fibers were originally developed as actuators for adaptive materials systems. Their properties, however, also allow their use as sensor or emitter-receiver in variours applications. After presenting selected characteristics, the potential of Active Fiber Composites for structural health monitoring is discussed in comparison with that of conventional piezoelectric elements. 相似文献
182.
The development of the semi-theoretical correlation in Hadzisdmajlovic et al. (1983) for predicting the maximum spoutable height in a spout-fluid bed, is observed to involve certain discrepancies. Based on their experimental data, a new correlation is proposed. 相似文献
183.
高科技纤维在摩擦制动材料中的应用 总被引:2,自引:0,他引:2
本文介绍了一些高科技纤维在聚俣物基摩擦材料中的使用情况,指出在摩擦材料中使用高科技纤维已成为摩擦材料的一个发展趋势,但需要大大提高高科技纤维的性价比和使用纤维混杂技术。 相似文献
184.
185.
Ch. LAFFORGUE F. CROUTE J.F. NICOLAS D.J. HARTMANN E. DELAPORTE J. COTTE M.C. MARTINI 《International journal of cosmetic science》1991,13(3):125-136
Antielastase activity of derivatives like 'propionylaminoacid'(C3 prolin, C3 hydroxyprolin, C3 collagen) was examined for pancreatic elastase, and fibroblastic elastase production. Essential metabolic variations of normal dermal fibroblasts were evaluated: adhesion, proliferation capacity, total protein biosynthesis and collagen type I and type III production. Possible other factors such as cellular nutrients were examined by oxygen consumption evaluation.
Propionylaminoacid derivatives have antielastase activities. Pancreatic elastase showed dose related inhibition (20% to 50% inhibition for concentration from 5 to 80 mg ml−1 .
Moreover, fibroblastic elastase production was inhibited, cellular respiration was enhanced. A very good tolerance in vitro was observed for concentration 0–1 mg ml−1 range: adhesion, proliferation capacity and collagen (type I and type III) production were not altered, and oxygen consumption was enhanced. 相似文献
Propionylaminoacid derivatives have antielastase activities. Pancreatic elastase showed dose related inhibition (20% to 50% inhibition for concentration from 5 to 80 mg ml
Moreover, fibroblastic elastase production was inhibited, cellular respiration was enhanced. A very good tolerance in vitro was observed for concentration 0–1 mg ml
186.
C. Chávez-Méndez. M.A. Salgado–Cervanres H.S. Garcia–Galindo. J.De la Cmz-Medina M.A Garcia-Alvarado 《Drying Technology》2013,31(8-9):2113-2122
ABSTRACT Non-linear regression was used to fit a high order kinetic model to drying curves for mango and cassava. For comparison purposes, the same experimental data were also adjusted by non-lines regression to a model based on exponential series, and to another exponential model by simple linear regression. The high order model fit the experimental data with higher precision (r2 Al.98) than the other exponential series models. The proposed higher order model is mathematically simple as compared to the exponential series, and could be used for simulation of drying processes. 相似文献
187.
Hollow polymeric nanocapsules with a thermosensitive membrane are prepared and characterized. They reversibly change their dimensions during temperature variations below and above the transition of the membrane. The nanocapsules were prepared by three steps: (i) well-defined mesoglobules prepared from an LCST polymer (hydroxyl end functionalized poly(2-isopropyl-2-oxazoline), PiPOZ-OH) were coated with a thermo-sensitive cross-linked shell formed via seeded radical copolymerization of N-isopropylacrylamide (NIPAM) and N,N′-bis-methylene acrylamide to produce core–shell nanoparticles (ii), which were subjected to extensive dialysis below the LCSTs of both the core-forming PiPOZ-OH and shell-forming PNIPAM to remove the core (iii). The use of a core-forming polymer of low molecular weight (<8900 g mol−1), narrow dispersity (<1.15) and relatively low Tg (52–68 °C) is beneficial as far as the effectiveness of the removal of the cores is concerned. The inherent immiscibility between PiPOZ-OH and PNIPAM as well as the specific raspberry-like structure of the core–shell particles also contributed for enhancement of the core removal effectiveness. 相似文献
188.
A. Dittmar Ch. GuguschevC. Hartmann S. GolkaA. Kwasniewski J. WollweberR. Fornari 《Journal of the European Ceramic Society》2011,31(14):2733-2739
Fine powders of WC, TaC and TaC with W and WC additives were cold-isostatically pressed to ceramic discs and pressurelessly sintered at temperatures up to 2100 °C in a second step. Afterwards, the discs were tested as crucible lid under typical AlN growth conditions. The prepared discs should be gas tight and ensure a better alignment of the thermal expansion coefficients of TaC lid and AlN.Ceramic discs densified by this method reveal a relative density up to 97%. The TaC ceramic discs without additives show a microstructure with grain sizes in the range of 10-200 μm after sintering. The grain enlargement could be reduced by W and WC additives in the range of 1-5 wt.%. The results show that the AlN boules adhere only to WC lids and tungsten containing lids with W contents higher than or equal to 3 wt.%. 相似文献
189.
190.
Kasarapu Venkataramana Chittimadula Madhuri Ch Madhusudan Y.Suresh Reddy G. Bhikshamaiah C.Vishnuvardhan Reddy 《Ceramics International》2018,44(6):6300-6310
In the present study, we investigate the fundamental properties of CeO2 by selecting La3+ (57), and Dy3+ (66) as dopants with optimized average atomic number of 61.5, which lies in between Pm3+ (62) and Sm3+ (62) in accordance with the criteria for optimum doping. A system of co-doped ceria ceramics Ce1–x–yLaxDyyO2-δ ((x, y) = (0.00, 0.00), (0.025, 0.025), (0.05, 0.05), (0.075, 0.075), (0.10, 0.10), (0.00, 0.20) and (0.20, 0.00)) as electrolytes for intermediate temperature solid oxide fuel cells were successfully prepared by a well-known sol-gel auto-combustion route. In order to obtain dense samples, the prepared pellets were sintered in air at 1300 °C for 4 h using conventional furnace and relative densities of all the samples were found to be higher than 95%. Single phase cubic structure, microstructural density and elemental composition analysis of all the samples were studied by powder X-ray diffraction, scanning electron microscope and energy dispersive spectroscopy techniques, respectively. Raman spectroscopy analysis confirmed the formation of concentrated O2-–vacancies in the co-doped ceria system. Impedance spectroscopy measurements revealed the high value of total ionic conductivity and low activation energy for the composition Ce0.85La0.075Dy0.075O2?δ i.e., 2.08 × 10–2 S cm–1 and 0.58 eV, respectively. Linear thermal expansion analyses of all the samples revealed the matched thermal expansion coefficients. Finally, these results recommend that the Ce0.85La0.075Dy0.075O2?δ sample can be useful as a solid electrolyte in IT-SOFC applications. 相似文献