全文获取类型
收费全文 | 1581630篇 |
免费 | 26517篇 |
国内免费 | 7064篇 |
专业分类
电工技术 | 34473篇 |
综合类 | 6563篇 |
化学工业 | 273840篇 |
金属工艺 | 65012篇 |
机械仪表 | 44212篇 |
建筑科学 | 48179篇 |
矿业工程 | 11443篇 |
能源动力 | 50338篇 |
轻工业 | 123350篇 |
水利工程 | 16177篇 |
石油天然气 | 37336篇 |
武器工业 | 139篇 |
无线电 | 197853篇 |
一般工业技术 | 295483篇 |
冶金工业 | 203638篇 |
原子能技术 | 33920篇 |
自动化技术 | 173255篇 |
出版年
2021年 | 15680篇 |
2019年 | 14727篇 |
2018年 | 15472篇 |
2017年 | 14644篇 |
2016年 | 21470篇 |
2015年 | 17532篇 |
2014年 | 28932篇 |
2013年 | 88247篇 |
2012年 | 37384篇 |
2011年 | 50229篇 |
2010年 | 43059篇 |
2009年 | 50918篇 |
2008年 | 46961篇 |
2007年 | 44301篇 |
2006年 | 46705篇 |
2005年 | 41053篇 |
2004年 | 43442篇 |
2003年 | 43210篇 |
2002年 | 42184篇 |
2001年 | 39502篇 |
2000年 | 37531篇 |
1999年 | 37242篇 |
1998年 | 57254篇 |
1997年 | 46717篇 |
1996年 | 40444篇 |
1995年 | 33892篇 |
1994年 | 31481篇 |
1993年 | 31046篇 |
1992年 | 27040篇 |
1991年 | 24365篇 |
1990年 | 24436篇 |
1989年 | 23558篇 |
1988年 | 22108篇 |
1987年 | 20295篇 |
1986年 | 19784篇 |
1985年 | 23147篇 |
1984年 | 22939篇 |
1983年 | 20851篇 |
1982年 | 19680篇 |
1981年 | 19765篇 |
1980年 | 18420篇 |
1979年 | 18927篇 |
1978年 | 18149篇 |
1977年 | 18849篇 |
1976年 | 21593篇 |
1975年 | 16302篇 |
1974年 | 15802篇 |
1973年 | 15864篇 |
1972年 | 13343篇 |
1971年 | 11977篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Yana Jorge Polizer-Rocha José M. Lorenzo Daniel Pompeu Isabela Rodrigues Juliana Cristina Baldin Manoela A. Pires Maria Teresa A. Freire Francisco Jose Barba Marco Antonio Trindade 《International Journal of Food Science & Technology》2020,55(3):1018-1024
This study aimed to evaluate the physicochemical characteristics and sensory attributes of beef burgers with the addition of pea fibre as a partial substitute of meat or fat. Three formulations were prepared: control (CON) – similar to the commercial formulation; fibre/less meat (FLM)—5% meat reduction and addition of 1% pea fibre; fibre/less fat (FLF)—7% fat reduction and addition of 1% pea fibre. Non-significant differences were obtained for pH, colour parameters (L* and b*), texture profile, cooking loss and size reduction among formulations. Moreover, sensory analysis with consumers of beef burgers did not indicate differences among the formulations for all the analysed attributes. Therefore, pea fibre is a promising partial replacer for meat and fat in beef burgers due to the preservation of technological parameters and sensory acceptance. 相似文献
13.
14.
The role of the following factors in the selection of technological bases for manufacturing is considered: the accessibility of the machined surfaces; their parameters and dimensional relationships; their position relative to the forces acting; and the uniformity of the margin distribution. 相似文献
15.
16.
A. L. Rudenko V. V. Mishakin A. V. Gonchar K. V. Kurashkin A. E. Fomin 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2020,53(6):687-689
At the hydroelectric unit No. 11 of the Nizhnekamsk hydroelectric power plant, the filling wedges of a rotor were investigated by ultrasound in the free st 相似文献
17.
Bianka Rocha Saraiva Lucas Henrique Maldonado da Silva Fernando Antônio Anjo Ana Carolina Pelaes Vital Jéssica Bassi Da Silva Marcos Luciano Bruschi Paula Toshimi Matumoto Pintro 《International Journal of Food Science & Technology》2020,55(5):1962-1970
Debittered trub (brewing waste) is an important source of protein source (70.26%). Trub and whey protein were used for 5% protein enrichment of ice cream frozen by liquid nitrogen. Three formulations were elaborated: ice cream standard (ICS), ice cream with whey protein (ICW) and ice cream with trub (ICT). Chemical composition, rheological properties, texture, overrun, melting rate, scanning electron microscopy and a sensorial test were performed. Results showed that ICT presented a higher viscosity, obtained on the upward curve up to 6.76 Pa s−1, consistency index (22.96 (Pa s−1)n), hysteresis area (140.40 mPa s−1) and hardness (31113.33 g) but a lower melting rate (0.38 g min−1), overrun (13.92%) and sensorial acceptability than the other formulations. The addition of trub debittered for protein enrichment improved ice cream properties and demonstrated that it could be used as a food ingredient. 相似文献
18.
Joel Kuula Heino Kuuluvainen Jarkko V. Niemi Erkka Saukko Harri Portin Anu Kousa 《Aerosol science and technology》2020,54(2):190-202
AbstractLung deposited surface area (LDSA) is a relatively new metric that has been argued to be more accurate at predicting health effects from aerosol exposure. For typical atmospheric aerosol, the LDSA concentration depends mainly on the concentration of ultrafine particles (e.g. vehicular exhaust emissions and residential wood combustion) and therefore optical methods cannot be used to measure and quantify it. The objective of this study was to investigate and describe typical characteristics of LDSA under different urban environments and evaluate how a diffusion charging-based Pegasor AQ Urban sensor (Pegasor Ltd., Finland) can be used as an alternative to optical sensors when assessing local combustion emissions and respective LDSA concentrations. Long-term (12?months) sensor measurements of LDSA were carried out at three distinctly different measurement sites (four sensor nodes) in the Helsinki metropolitan area, Finland. The sites were affected mainly by vehicular exhaust emission (street canyon and urban background stations) and by residential wood combustion (two detached housing area stations). The results showed that the accuracy of the AQ Urban was good (R2 = 0.90) for the measurement of LDSA when compared to differential mobility particle sizer. The mean concentrations of LDSA were more than twice as high at the street canyon (mean 22 µm2 cm?3) site when compared to the urban background site (mean 9.4 µm2 cm?3). In the detached housing area, the mean concentrations were 12 µm2 cm?3, and wood combustion typically caused high LDSA peaks in the evenings. High correlations and similar diurnal cycles were observed for the LDSA and black carbon at street canyon and urban background stations. The utilization of a small-scale sensor network (four nodes) showed that the cross-station variability in hourly LDSA concentrations was significant in every site, even within the same detached housing area (distance between the two sites ~670?m). 相似文献
19.
Bankov S. E. Vesnik M. V. Kravchenko V. F. 《Journal of Communications Technology and Electronics》2020,65(4):398-405
Journal of Communications Technology and Electronics - Abstract—The article presents a rigorous numerical solution, using the Wiener–Hopf method, to the problem of plane wave... 相似文献
20.
The proliferating need for sustainability intervention in food grain transportation planning is anchoring the attention of researchers in the interests of stakeholders and environment at large. Uncertainty associated with food grain supply further intensifies the problem steering the need for designing robust, cost-efficient and sustainable models. In line with this, this paper aims to develop a robust and sustainable intermodal transportation model to facilitate single type of food grain commodity shipments while considering procurement uncertainty, greenhouse gas emissions, and intentional hub disruption. The problem is designed as a mixed integer non-linear robust optimisation model on a hub and spoke network for evaluating near optimal shipment quantity, route selection and hub location decisions. The robust optimisation approach considers minimisation of total relative regret associated with total cost subject to several real-time constraints. A version of Particle Swarm Optimisation with Differential Evolution is proposed to tackle the resulting NP-hard problem. The model is tested with two other state-of the art meta-heuristics for small, medium, and large datasets subject to different procurement scenarios inspired from real time food grain operations in Indian context. Finally, the solution is evaluated with respect to total cost, model and solution robustness for all instances. 相似文献