全文获取类型
收费全文 | 48244篇 |
免费 | 2780篇 |
国内免费 | 242篇 |
专业分类
电工技术 | 727篇 |
综合类 | 292篇 |
化学工业 | 9593篇 |
金属工艺 | 1300篇 |
机械仪表 | 1312篇 |
建筑科学 | 1499篇 |
矿业工程 | 190篇 |
能源动力 | 1607篇 |
轻工业 | 5816篇 |
水利工程 | 430篇 |
石油天然气 | 387篇 |
武器工业 | 15篇 |
无线电 | 3418篇 |
一般工业技术 | 8984篇 |
冶金工业 | 8658篇 |
原子能技术 | 327篇 |
自动化技术 | 6711篇 |
出版年
2023年 | 610篇 |
2022年 | 734篇 |
2021年 | 1620篇 |
2020年 | 1367篇 |
2019年 | 1370篇 |
2018年 | 2021篇 |
2017年 | 1786篇 |
2016年 | 1901篇 |
2015年 | 1420篇 |
2014年 | 1977篇 |
2013年 | 3693篇 |
2012年 | 2494篇 |
2011年 | 2637篇 |
2010年 | 2054篇 |
2009年 | 1978篇 |
2008年 | 1887篇 |
2007年 | 1702篇 |
2006年 | 1306篇 |
2005年 | 995篇 |
2004年 | 778篇 |
2003年 | 723篇 |
2002年 | 626篇 |
2001年 | 532篇 |
2000年 | 527篇 |
1999年 | 618篇 |
1998年 | 2655篇 |
1997年 | 1728篇 |
1996年 | 1193篇 |
1995年 | 736篇 |
1994年 | 593篇 |
1993年 | 588篇 |
1992年 | 270篇 |
1991年 | 248篇 |
1990年 | 224篇 |
1989年 | 215篇 |
1988年 | 200篇 |
1987年 | 215篇 |
1986年 | 200篇 |
1985年 | 287篇 |
1984年 | 248篇 |
1983年 | 222篇 |
1982年 | 198篇 |
1981年 | 239篇 |
1980年 | 230篇 |
1979年 | 170篇 |
1978年 | 154篇 |
1977年 | 309篇 |
1976年 | 608篇 |
1975年 | 126篇 |
1973年 | 150篇 |
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
1.
Journal of Low Temperature Physics - This study modeled and investigated the magnetocaloric effect in Ni2MnGa Heusler alloy characterized by its magnetic entropy change (ΔSm) and its... 相似文献
2.
Khan Saleem Ali Shawkat Khan Arshad Bermak Amine 《Journal of Materials Science: Materials in Electronics》2022,33(1):541-553
Journal of Materials Science: Materials in Electronics - This work presents an interesting fabrication route toward development of pressure sensing patch by utilizing electrically conductive cotton... 相似文献
3.
In the present work, the heating performance of a new system combined with a new modified baseboard radiator and fan coil is investigated. Using longitudinal fins with special geometry and also forced airflow at the end of the system causes that at the lower inlet water temperature compared with the conventional models, higher heat output rate be obtained. The heat output rate of the new modified system is obtained by experimental metrology based on the European Standard No. EN-442. Temperature and velocity distribution in the room space is done by simulation of the modified system in the Flovent software. Computational fluid dynamics (CFD) results are validated against experimental results and there is a good agreement between them. Also, the energy consumption of the system during the winter season is calculated in TRANSYS software. Experimental results show that the heat output rate of a new modified heating system with inlet water temperature in the range of 45–55°C is on average 4.17 times higher compared with the conventional model. CFD simulation also showed that the combined system provides good thermal comfort conditions. Energy consumption of the new system reduced about 13% compared with conventional models. 相似文献
4.
The present article investigates the influence of Joule heating and chemical reaction on magneto Casson nanofluid phenomena in the occurrence of thermal radiation through a porous inclined stretching sheet. Consideration is extended to heat absorption/generation and viscous dissipation. The governing partial differential equations were transformed into nonlinear ordinary differential equations and numerically solved using the Implicit Finite Difference technique. The article analyses the effect of various physical flow parameters on velocity, heat, and mass transfer distributions. For the various involved parameters, the graphical and numerical outcomes are established. The analysis reveals that the enhancement of the radiation parameter increases the temperature and the chemical reaction parameter decreases the concentration profile. The empirical data presented were compared with previously published findings. 相似文献
5.
Duparc Estelle Möller Frederik Jussen Ilka Stachon Maleen Algac Sükran Otto Boris 《Electronic Markets》2022,32(2):727-745
Electronic Markets - The open-source paradigm offers a plethora of opportunities for innovative business models (BMs) as the underlying codebase of the technology is accessible and extendable by... 相似文献
6.
Gross Jürgen Peter Malzbender Jürgen Schwaiger Ruth 《Journal of Materials Science》2022,57(15):7481-7490
Journal of Materials Science - The application of ceramics in advanced functional applications often requires thicknesses below a few hundred micrometers, rendering an assessment of the... 相似文献
7.
Khaled Al-Farhany Mohammed A. Alomari Ahmed Al-Saadi Ali Chamkha Hakan F. Öztop Wael Al-Kouz 《亚洲传热研究》2022,51(2):1691-1710
In the current work, numerical simulations are achieved to study the properties and the characteristics of fluid flow and heat transfer of (Cu–water) nanofluid under the magnetohydrodynamic effects in a horizontal rectangular canal with an open trapezoidal enclosure and an elliptical obstacle. The cavity lower wall is grooved and represents the heat source while the obstacle represents a stationary cold wall. On the other hand, the rest of the walls are considered adiabatic. The governing equations for this investigation are formulated, nondimensionalized, and then solved by Galerkin finite element approach. The numerical findings were examined across a wide range of Richardson number (0.1 ≤ Ri ≤ 10), Reynolds number (1 ≤ Re ≤ 125), Hartmann number (0 ≤ Ha ≤ 100), and volume fraction of nanofluid (0 ≤ φ ≤ 0.05). The current study's findings demonstrate that the flow strength increases inversely as the Reynolds number rises, which pushes the isotherms down to the lower part of the trapezoidal cavity. The Nuavg rises as the Ri rise, the maximum Nuavg = 10.345 at Ri = 10, Re = 50, ϕ = 0.05, and Ha = 0; however, it reduces with increasing Hartmann number. Also, it increase by increasing ϕ, at Ri = 10, the Nuavg increased by 8.44% when the volume fraction of nanofluid increased from (ϕ = 0–0.05). 相似文献
8.
9.
Güzin Kaban Selen Sallan Kübra Çinar Topçu Bilge Sayın Börekçi Mükerrem Kaya 《International Journal of Food Science & Technology》2022,57(7):4392-4399
The study aims to evaluate the technological properties of autochthonous strains (Lactobacillus sakei S15, Lactobacillus plantarum S24, L. plantarum S91, Pediococcus pentosaceus S128b and Staphylococcus carnosus G109) in Turkish dry fermented sausage (sucuk). After 24 h of fermentaPtion, all lactic acid bacteria strains reduced the pH to below 5.0, while the pH in the control group was above 5.3. The number of lactic acid bacteria strains reached 108–109 cfu g−1 during fermentation. Staphylococcus carnosus G109 remained at the inoculation level of 106 cfu g−1 during ripening. Lactobacillus sakei S15 as mono-culture showed higher TBARS values compared to other strains. The control group had the lowest L* value and autochthonous strains caused no significant difference for a* value. According to principal component analysis results, most volatile compounds were positively correlated with the group containing only L. sakei S15. 相似文献
10.
Stumpo Vittorio Sebök Martina van Niftrik Christiaan Hendrik Bas Seystahl Katharina Hainc Nicolin Kulcsar Zsolt Weller Michael Regli Luca Fierstra Jorn 《Magma (New York, N.Y.)》2022,35(1):29-44
Magnetic Resonance Materials in Physics, Biology and Medicine - Innovative physiologic MRI development focuses on depiction of heterogenous vascular and metabolic features in glioblastoma. For this... 相似文献