全文获取类型
收费全文 | 321篇 |
免费 | 30篇 |
专业分类
综合类 | 1篇 |
化学工业 | 104篇 |
金属工艺 | 10篇 |
机械仪表 | 7篇 |
建筑科学 | 12篇 |
能源动力 | 31篇 |
轻工业 | 39篇 |
水利工程 | 5篇 |
石油天然气 | 9篇 |
无线电 | 28篇 |
一般工业技术 | 46篇 |
冶金工业 | 8篇 |
自动化技术 | 51篇 |
出版年
2024年 | 2篇 |
2023年 | 8篇 |
2022年 | 15篇 |
2021年 | 25篇 |
2020年 | 22篇 |
2019年 | 18篇 |
2018年 | 36篇 |
2017年 | 29篇 |
2016年 | 26篇 |
2015年 | 20篇 |
2014年 | 18篇 |
2013年 | 38篇 |
2012年 | 18篇 |
2011年 | 24篇 |
2010年 | 15篇 |
2009年 | 9篇 |
2008年 | 7篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 1篇 |
2002年 | 4篇 |
1998年 | 3篇 |
1981年 | 1篇 |
排序方式: 共有351条查询结果,搜索用时 15 毫秒
31.
32.
33.
A. Shahrjerdi F. Mustapha M. Bayat D. L. A. Majid 《Journal of Mechanical Science and Technology》2011,25(9):2195-2209
Second-order shear deformation theory (SSDT) is employed to analyze vibration of temperature-dependent solar functionally
graded plates (SFGP’s). Power law material properties and linear steady-state thermal loads are assumed to be graded along
the thickness. Two different types of SFGP’s such as ZrO2/Ti-6Al-4V and Si3N4/SUS304 are considered. Uniform, linear, nonlinear, heat-flux and sinusoidal thermal conditions are imposed at the upper and
lower surface for simply supported SFGPs. The energy method is applied to derive equilibrium equations, and solution is based
on Fourier series that satisfy the boundary conditions (Navier’s method). Non-dimensional results are compared for temperature-dependent
and temperature-independent SFGP’s and validated with known results in the literature. Numerical results indicate the effect
of material composition, plate geometry, and temperature fields on the vibration characteristics and mode shapes. The results
obtained using the SSDT are very close to results from other shear deformation theories. 相似文献
34.
Mari J. Jaakamo Tytti J. Luukkonen Piia K. Kairenius Ali R. Bayat Seppo A. Ahvenjärvi Tuomo M. Tupasela Johanna H. Vilkki Kevin J. Shingfield Heidi M. Leskinen 《Journal of dairy science》2019,102(10):8825-8838
We examined the effects of 2 grass silage-based diets differing in forage:concentrate (FC) ratio and those of a red clover silage-based diet on intake, milk production, ruminal fatty acid (FA) biohydrogenation, milk FA composition, and milk fat globule (MFG) size distribution. Ten multiparous Nordic Red cows received the following treatments: grass silage-based diets containing high (70:30, HG) or low (30:70, LG) FC ratio or a red clover silage-based diet with an FC ratio of 50:50 (RC) on a dry matter basis. Determinations of MFG were performed from fresh milk samples without addition of EDTA so the results of fat globules >1 µm in diameter are emphasized instead of the entire globule population. Lower FC ratio in grass silage-based diets increased milk production with no effect on daily fat yield, leading to 13% lower milk fat concentration. The effect of FC ratio on MFG size was moderate. It did not affect the volume-weighted diameter in grass silage-based diets, although LG lowered the volume-surface diameter of MFG in the size class >1 µm compared with HG. Compared with HG, feeding LG moderately decreased the biohydrogenation of 18:2n-6, leading to a higher level of polyunsaturated fatty acids in milk fat. Feeding RC lowered milk fat concentration and daily milk fat yield compared with grass silage-based diets. The volume-weighted diameter of MFG in the size class >1 µm was smaller in RC milk compared with grass silage-based diets. Feeding RC increased the flow of 18:3n-3 at the omasum by 2.4-fold and decreased the apparent ruminal 18:3n-3 biohydrogenation compared with grass silage-based diets despite similar intake of 18:3n-3. It also resulted in the lowest amount of saturated FA and the highest amounts of cis-9 18:1, 18:3n-3, and polyunsaturated FA in milk. In conclusion, LG decreased milk fat content and induced minor changes in MFG size distribution compared with HG, whereas RC lowered milk fat production, altered milk FA composition to nutritionally more beneficial direction, and led to smaller MFG compared with grass silage-based diets. 相似文献
35.
36.
City logistics is one of the significant branches of supply chain management, dealing with the logistics and transportation activities in urban areas. This research area has recently appropriated an exponential growth of publications. This paper presents a bibliometric analysis along with a systematic literature review to organise the results of surveying more than 370 papers and research works published since 2010. We identify the top contributing research topics. The most common keywords used in the city logistics literature are referred to in order to propose six research categories identifying the main innovative research perspectives. 相似文献
37.
Goudarzi Parisa Rahmani Amir Masoud Mosleh Mohammad 《The Journal of supercomputing》2022,78(15):17202-17230
The Journal of Supercomputing - The cloud of things (CloudIoT) represents a general system of supporting infrastructure for storing and processing information gathered from smart objects and their... 相似文献
38.
The Journal of Supercomputing - Depression is the most prevalent mental disorder that can lead to suicide. Due to the tendency of people to share their thoughts on social platforms, social data... 相似文献
39.
40.
In time division duplex (TDD)‐based multiuser massive multiple input multiple output (MIMO) systems, the uplink channel is estimated and the results are used in downlink for signal detection. Owing to noisy uplink channel estimation, the downlink channel should also be estimated for accurate signal detection. Therefore, recently, a blind method was developed, which assumes the use of a linear high‐power amplifier (HPA) in the base station (BS). In this study, we extend this method to a scenario with a nonlinear HPA in the BS, where the Bussgang decomposition is used for HPA modeling. In the proposed method, the average power of the received signal for each user is a function of channel gain, large‐scale fading, and nonlinear distortion variance. Therefore, the channel gain is estimated, which is required for signal detection. The performance of the proposed method is analyzed theoretically. The simulation results show superior performance of the proposed method compared to that of the other methods in the literature. 相似文献