全文获取类型
收费全文 | 728篇 |
免费 | 41篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 9篇 |
综合类 | 1篇 |
化学工业 | 133篇 |
金属工艺 | 23篇 |
机械仪表 | 30篇 |
建筑科学 | 21篇 |
矿业工程 | 3篇 |
能源动力 | 40篇 |
轻工业 | 78篇 |
水利工程 | 9篇 |
石油天然气 | 1篇 |
无线电 | 77篇 |
一般工业技术 | 208篇 |
冶金工业 | 74篇 |
自动化技术 | 63篇 |
出版年
2024年 | 1篇 |
2023年 | 13篇 |
2022年 | 25篇 |
2021年 | 37篇 |
2020年 | 24篇 |
2019年 | 16篇 |
2018年 | 37篇 |
2017年 | 31篇 |
2016年 | 34篇 |
2015年 | 27篇 |
2014年 | 46篇 |
2013年 | 55篇 |
2012年 | 32篇 |
2011年 | 43篇 |
2010年 | 31篇 |
2009年 | 35篇 |
2008年 | 35篇 |
2007年 | 28篇 |
2006年 | 28篇 |
2005年 | 23篇 |
2004年 | 25篇 |
2003年 | 10篇 |
2002年 | 8篇 |
2001年 | 8篇 |
2000年 | 3篇 |
1999年 | 13篇 |
1998年 | 5篇 |
1997年 | 15篇 |
1996年 | 9篇 |
1995年 | 14篇 |
1994年 | 13篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 6篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 5篇 |
1973年 | 1篇 |
排序方式: 共有770条查询结果,搜索用时 9 毫秒
141.
On the development of an apatitic calcium phosphate bone cement 总被引:1,自引:0,他引:1
Development of an apatitic calcium phosphate bone cement is reported. 100 μ Particles of tetracalcium phosphate (TTCP) and
dicalcium phosphate dihydrate (DCPD) were mixed in equimolar ratio to form the cement powder. The wetting medium used was
distilled water with Na2HPO4 as accelerator to manipulate the setting time. The cement powder, on wetting with the medium, formed a workable putty. The
setting times of the putty were measured using a Vicat type apparatus and the compressive strength was determined with a Universal
Testing Machine. The nature of the precipitated cement was analyzed through X-ray diffraction (XRD), fourier transform infrared
spectrometry (FTIR) and energy dispersive electron microprobe (EDAX). The results showed the phase to be apatitic with a calcium-to-phosphorous
ratio close to that of hydroxyapatite. The microstructure analysis using scanning electron microscopy (SEM) showed hydroxyapatite
nano-crystallite growth over particulate matrix surface. The structure has an apparent porosity of ∼ 52%. There were no appreciable
dimensional or thermal changes during setting. The cement passed the in vitro toxicological screening (cytotoxicity and haemolysis)
tests. Optimization of the cement was done by manipulating the accelerator concentration so that the setting time, hardening
time and the compressive strength had clinically relevant values. 相似文献
142.
Investigation of Heat Transfer in Serpentine Shaped Microchannel Using Al2O3/Water Nanofluid 下载免费PDF全文
An experimental investigation was conducted to explore the maximum heat transfer in a serpentine shaped microchannel by varying the hydraulic diameter, flow rates and with influence of Al2O3 nanofluid. Microconvection is an important area in heat transport phenomena. Surface area is one of the important factors in high heat transfer in a microchannel heat exchanger. In this study, serpentine shaped microchannels of hydraulic diameters 810, 830, 860, and 890 μm are analyzed for the optimizing the hydraulic diameter to get enhanced thermal performance of the microchannel. A copper material microchannel having length a of 70 mm is used. Flow rate also varied from 1 lpm (Litres per minute) to 3.5 lpm for optimization with nanofluid as a medium. From numerical study it is observed that as the hydraulic diameter decreases from 890 μm to 810 μm the pressure drop increases with a decrease in hydraulic diameter. Also as heat input to the microchannel increases from 5 watts to 70 watts. From analysis it is observed that the hydraulic diameter of the microchannel is a major factor in microchannel heat transfer which is dependent on flow rate of fluid in the microchannel. The results also show that suspended Al2O3 nanoparticles in fluids have enhanced heat transfer when compared to the base fluid. 相似文献
143.
Sivakumar Bakthavachalu Miguel A. Labrador 《International Journal of Communication Systems》2004,17(8):763-778
The TFRC protocol has been proposed as a TCP‐friendly protocol to transport streaming media over the Internet. However, its deployment is still questionable because it has not been compared to other important protocols, analysed in the presence of important mechanisms, such as the explicit congestion notification (ECN), and studied under more realistic network conditions. In this paper, we address these three aspects, including other congestion control protocols not considered before in the same investigation, such as TCP Tahoe, Reno, Newreno, Vegas, Sack, GAIMD, and the Binomial algorithms, the effect of using ECN in the friendliness of the protocols, and the fairness of the protocols under static and dynamic network conditions. We found that TFRC can be safely deployed in the Internet if competing with TCP Tahoe, New Reno and SACK since fairness is achieved under all scenarios considered. We also found that ECN actually helps in achieving better fairness. However, fairness problems arise when TFRC competes with TCP Reno, GAIMD, SQRT or IIAD in static or dynamic conditions, or both. We used normalized throughput, fairness index, and convergence time as the main performance metrics for comparison. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
144.
Vasanthapriya R. Neelakandeswari N. Uthayarani K. Chitra M. 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(11):4272-4280
Journal of Inorganic and Organometallic Polymers and Materials - This paper reports the performance of alizarin based SnO2 dye-sensitized solar cells. A novel template assisted method has been... 相似文献
145.
Chitra Sivakumar Catherine Rui Jin Findlay Chithra Karunakaran Jitendra Paliwal 《Comprehensive Reviews in Food Science and Food Safety》2023,22(3):1613-1632
The consumption of plant-based proteins sourced from pulses is sustainable from the perspective of agriculture, environment, food security, and nutrition. Increased incorporation of high-quality pulse ingredients into foods such as pasta and baked goods is poised to produce refined food products to satisfy consumer demand. However, a better understanding of pulse milling processes is required to optimize the blending of pulse flours with wheat flour and other traditional ingredients. A thorough review of the state-of-the-art on pulse flour quality characterization reveals that research is required to elucidate the relationships between the micro- and nanoscale structures of these flours and their milling-dependent properties, such as hydration, starch and protein quality, components separation, and particle size distribution. With advances in synchrotron-enabled material characterization techniques, there exist a few options that have the potential to fill knowledge gaps. To this end, we conducted a comprehensive review of four high-resolution nondestructive techniques (i.e., scanning electron microscopy, synchrotron X-ray microtomography, synchrotron small-angle X-ray scattering, and Fourier-transformed infrared spectromicroscopy) and a comparison of their suitability for characterizing pulse flours. Our detailed synthesis of the literature concludes that a multimodal approach to fully characterize pulse flours will be vital to predicting their end-use suitability. A holistic characterization will help optimize and standardize the milling methods, pretreatments, and post-processing of pulse flours. Millers/processors will benefit by having a range of well-understood pulse flour fractions to incorporate into food formulations. 相似文献
146.
Abdelsalam Ahmed M. Elsheikh Ahmed Chidambaram Sivakumar David Jean-Pierre Langlois J. M. Pierre 《Journal of Signal Processing Systems》2020,92(1):95-107
Journal of Signal Processing Systems - Convolutional Neural Networks (CNNs) and Deep Neural Networks (DNNs) have gained significant popularity in several classification and regression applications.... 相似文献
147.
Awdhesh Kumar Choudhary Bhardwaj Pandit G.L. Sivakumar Babu 《Geotextiles and Geomembranes》2019,47(2):203-216
The paper investigates the uplift performance of horizontal anchor plate in geocell reinforced sand through a series of model tests. It is noted that the unreinforced anchor plate undergoes a clear failure at a displacement of about 3% of its width, whereas with the provision of geocell and a layer of geotextile right below the geocell mattress significantly increases the uplift capacity by about 4.5 times higher than that of unreinforced sand and could sustain anchor displacement of more than 60%. Results indicates that the geocell mattress by virtue of its rigidity distributes the uplift load in the lateral directions to a larger area, thereby reducing the stress in the overlying soil mass and hence increases the performance of anchor plate system. The provision of the additional geotextile layer right below the geocell mattress is found to be very effective in increasing the stiffness as well as load carrying capacity of anchor plate system. The optimum size (i.e., width and length) of geocell mattress giving adequate load carrying capacity of anchor plate is found to be 5.4 times of anchor width (5.4B). The comparison of model tests results with 3D numerical analysis shows good agreement, indicating that the proposed model is able to capture the uplift load-displacement behaviour of geocell reinforced anchor plate system. 相似文献
148.
149.
The deactivation disguised kinetic schemes in an isothermal transport reactor are differentiated theoretically by wave front analysis. Riemann's integration method is applied to the linearised hyperbolic partial differential equations describing the reactor dynamics for a small step change in inlet concentration. It is shown that the front of the outlet concentration wave is different for deactivation disguised kinetic schemes even though the final steady states are the same. For the startup condition, where the linearised model is not valid, the wave front is obtained by solving numerically the original partial differential equations. @KEYWORDS: Transport reactors, Deactivation disguised kinetics, Wave front analysis. 相似文献
150.