全文获取类型
收费全文 | 6066篇 |
免费 | 178篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 79篇 |
综合类 | 2篇 |
化学工业 | 1233篇 |
金属工艺 | 127篇 |
机械仪表 | 113篇 |
建筑科学 | 357篇 |
矿业工程 | 6篇 |
能源动力 | 145篇 |
轻工业 | 485篇 |
水利工程 | 46篇 |
石油天然气 | 10篇 |
武器工业 | 2篇 |
无线电 | 381篇 |
一般工业技术 | 946篇 |
冶金工业 | 1212篇 |
原子能技术 | 45篇 |
自动化技术 | 1062篇 |
出版年
2021年 | 69篇 |
2020年 | 62篇 |
2019年 | 94篇 |
2018年 | 91篇 |
2017年 | 77篇 |
2016年 | 98篇 |
2015年 | 100篇 |
2014年 | 136篇 |
2013年 | 352篇 |
2012年 | 237篇 |
2011年 | 337篇 |
2010年 | 270篇 |
2009年 | 245篇 |
2008年 | 324篇 |
2007年 | 279篇 |
2006年 | 257篇 |
2005年 | 199篇 |
2004年 | 196篇 |
2003年 | 175篇 |
2002年 | 185篇 |
2001年 | 99篇 |
2000年 | 74篇 |
1999年 | 83篇 |
1998年 | 80篇 |
1997年 | 82篇 |
1996年 | 85篇 |
1995年 | 102篇 |
1994年 | 105篇 |
1993年 | 96篇 |
1992年 | 92篇 |
1991年 | 65篇 |
1990年 | 75篇 |
1989年 | 94篇 |
1988年 | 62篇 |
1987年 | 58篇 |
1986年 | 80篇 |
1985年 | 96篇 |
1984年 | 78篇 |
1983年 | 93篇 |
1982年 | 84篇 |
1981年 | 87篇 |
1980年 | 72篇 |
1979年 | 77篇 |
1978年 | 58篇 |
1977年 | 65篇 |
1976年 | 59篇 |
1975年 | 66篇 |
1974年 | 47篇 |
1973年 | 53篇 |
1972年 | 35篇 |
排序方式: 共有6251条查询结果,搜索用时 15 毫秒
1.
2.
María Carrascal Pablo Sendra Antonio Alanís Plácido González Martínez Alfonso Guajardo-Fajardo 《Journal of Urbanism》2019,12(1):60-82
The creative city approach is going through a redefinition after the 2008 global financial crisis. In the specific case of South-European cities, in the context of austerity and cuts in public investment, creativity is becoming a strategy for achieving maximum social benefit and improvement of the built environment with minimum economic expenditure. This paper looks at this redefinition of creativity through the case study of Seville, in southern Spain. Through research methods that include video-recorded testimonies of the actors involved, mapping at the online platform “Laboratorio Q”, and public engagement activities, this paper explores how the civic society, professional, and public authorities have reinvented how to produce collective spaces. The paper concludes that bottom-up creative processes for producing collective spaces have become more visible since the 2008 crisis, when architects, planners, public authorities and policy-makers have been “learning” from them. 相似文献
3.
Moschetti Michael Xu Alan Schuh Benjamin Hohenwarter Anton Couzinié Jean-Philippe Kruzic Jamie J. Bhattacharyya Dhriti Gludovatz Bernd 《JOM Journal of the Minerals, Metals and Materials Society》2020,72(1):130-138
JOM - Refractory high-entropy alloys (RHEAs) are potential candidate materials for use in next-generation nuclear reactors due to their excellent mechanical performance at high temperatures. Here,... 相似文献
4.
Similarities and differences between male and female novice designers on color‐concept associations for warnings,action required,and signs and equipment status messages 下载免费PDF全文
This research examined the male and female novice designers toward color associations for the concepts used for ‘warnings’, ‘action required’, and ‘signs and equipment status’ through a questionnaire‐based study. A total of 178 Hong Kong Chinese final year undergraduate design students (89 males and 89 females) participated in the study. The test used required the participants to indicate their choice of one of nine colors to associations with each of 38 concepts in a color‐concept table, so that any one color could be associated with any one of the concepts. For both male and female groups of novice designers, chi‐square tests revealed a strong color association for each concept tested in this study (P < .05). The results showed males and females agreed on some color‐concept association stereotypes which were therefore gender neutral. The male and female novice designers had the same color associations and similar levels of stereotype strengths for 21 concepts. The nine strongest and therefore most useful color‐concept association stereotypes for both male and female novice designers were: red‐danger, red‐fire, red‐hot, red‐stop, red‐emergency, red‐error, blue‐cold, blue‐male, and green‐exit. However, the male and female novice designers had different color association stereotypes for the standby (green vs. yellow), emergency exit (green vs. red), and toxic (purple vs. black) concepts, and the strengths of the 14 remaining associations for both groups were not at equivalent levels. Overall, it is anticipated that the findings of this study will act as a useful reference for novice designers and other design practitioners to optimize color coding in the design of ‘warnings’, ‘action required’, and ‘signs and equipment status’ messages. 相似文献
5.
6.
7.
Carlos R. Arza Patric Jannasch Peter Johansson Per Magnusson Alan Werker Frans H. J. Maurer 《应用聚合物科学杂志》2015,132(15)
Thermal degradation of poly[(R)−3‐hydroxybutyric acid] (PHB) during melt mixing results in random chain scission that produces shorter polymer chains containing crotonic and carboxyl end groups. One way of preventing this serious reduction of molar mass is to add agents that react with at least two of the newly generated end groups. Different types of commercially available additives known to react with carboxyl group, namely bis(3,4‐epoxycyclohexylmethyl) adipate (BECMA), 2,2'‐bis(2‐oxazoline) (BOX), trimethylolpropane tris(2‐methyl‐1‐aziridinepropionate) (PETAP), triphenyl phosphate (TPP), tris(nonylphenyl) phosphate (TNPP), polycarbodiimide (PCDI), and poly(methyl metharylate‐co‐glycidyl methacrylate) (GMA.MMA) were mixed with PHB by cocasting from solution in chloroform. Dynamic rheology as well as measurements of molar masses before and after dynamic analysis was used to evaluate the effect of the additives on the melt stability of PHB. Measurements of the dynamic shear modulus and the molar mass of molten PHB with the additives PCDI and GMA.MMA showed a minor improvement on the thermal stability. Furthermore, TPP and TNPP did not affect the thermal stability of PHB, whereas the presence of BECMA, BOX, and PETAP gave a strong decrease of the dynamic modulus compared with neat PHB. © 2014 The Authors Journal of Applied Polymer Science Published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41836. 相似文献
8.
Puneet Parmar Nicolas Lopez-Villalobos John T. Tobin Eoin Murphy Frank Buckley Shane V. Crowley Alan L. Kelly Laurence Shalloo 《International Journal of Food Science & Technology》2021,56(5):2415-2422
The objective of this study was to determine the effect of temperature on whole milk density measured at four different temperatures: 5, 10, 15, and 20 °C. A total of ninety-three individual milk samples were collected from morning milking of thirty-two Holstein Friesian dairy cows, of national average genetic merit, once every two weeks over a period of 4 weeks and were assessed by Fourier transform infrared spectroscopy for milk composition analysis. Density of the milk was evaluated using two different analytical methods: a portable density meter DMA35 and a standard desktop model DMA4500M (Anton Paar GmbH, UK). Milk density was analysed with a linear mixed model with the fixed effects of sampling period, temperature and analysis method; triple interaction of sampling period x analysis method x temperature; and the random effect of cow to account for repeated measures. The effect of temperature on milk density (ρ) was also evaluated including temperature (t) as covariate with linear and quadratic effects within each analytic method. The regression equation describing the curvature and density–temperature relationship for the DMA35 instrument was ρ = 1.0338−0.00017T−0.0000122T2 (R2 = 0.64), while it was ρ = 1.0334 + 0.000057T−0.00001T2 (R2 = 0.61) for DMA4500 instrument. The mean density determined with DMA4500 at 5 °C was 1.0334 g cm−3, with corresponding figures of 1.0330, 1.0320 and 1.0305 g cm−3 at 10, 15 and 20 °C, respectively. The milk density values obtained in this study at specific temperatures will help to address any bias in weight–volume calculations and thus may also improve the financial and operational control for the dairy processors in Ireland and internationally. 相似文献
9.
Alan Pasha Tabatabai Daniel S. Seara Joseph Tibbs Vikrant Yadav Ian Linsmeier Michael P. Murrell 《Advanced functional materials》2021,31(10):2006745
Unlike nearly all engineered materials which contain bonds that weaken under load, biological materials contain “catch” bonds which are reinforced under load. Consequently, materials, such as the cell cytoskeleton, can adapt their mechanical properties in response to their state of internal, non-equilibrium (active) stress. However, how large-scale material properties vary with the distance from equilibrium is unknown, as are the relative roles of active stress and binding kinetics in establishing this distance. Through course-grained molecular dynamics simulations, the effect of breaking of detailed balance by catch bonds on the accumulation and dissipation of energy within a model of the actomyosin cytoskeleton is explored. It is found that the extent to which detailed balance is broken uniquely determines a large-scale fluid-solid transition with characteristic time-reversal symmetries. The transition depends critically on the strength of the catch bond, suggesting that active stress is necessary but insufficient to mount an adaptive mechanical response. 相似文献
10.