全文获取类型
收费全文 | 777篇 |
免费 | 48篇 |
专业分类
电工技术 | 22篇 |
综合类 | 3篇 |
化学工业 | 166篇 |
金属工艺 | 12篇 |
机械仪表 | 27篇 |
建筑科学 | 12篇 |
能源动力 | 60篇 |
轻工业 | 31篇 |
水利工程 | 11篇 |
石油天然气 | 1篇 |
无线电 | 78篇 |
一般工业技术 | 190篇 |
冶金工业 | 58篇 |
原子能技术 | 4篇 |
自动化技术 | 150篇 |
出版年
2024年 | 6篇 |
2023年 | 19篇 |
2022年 | 36篇 |
2021年 | 40篇 |
2020年 | 37篇 |
2019年 | 33篇 |
2018年 | 42篇 |
2017年 | 58篇 |
2016年 | 56篇 |
2015年 | 23篇 |
2014年 | 33篇 |
2013年 | 61篇 |
2012年 | 39篇 |
2011年 | 47篇 |
2010年 | 45篇 |
2009年 | 33篇 |
2008年 | 14篇 |
2007年 | 21篇 |
2006年 | 18篇 |
2005年 | 14篇 |
2004年 | 11篇 |
2003年 | 18篇 |
2002年 | 12篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 8篇 |
1997年 | 10篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 2篇 |
排序方式: 共有825条查询结果,搜索用时 31 毫秒
81.
Multi-walled carbon nanotube (MWCNT)-based composites have been prepared by in situ technique using Mesua ferrea L. seed oil-based hyperbranched polyurethane (HBPU) as the matrix. The scanning electron microscope, transmission electron microscope and Fourier transform infrared spectroscopy analyses revealed good dispersion as well as interaction of MWCNT with the matrix. Remarkable recovery of shape to the extent of 98% was obtained after composite formation. More than 300% improvement in tensile strength was observed as compared to the pristine HBPU. Significant enhancement of thermal stability up to 275 °C was found even at low MWCNT loading (1 wt.%). Bacterial degradation of the composite films was tested using two strains of Pseudomonas aeruginosa, MTCC 7814 and MTCC 7815. The composites exhibited enhanced biodegradability as compared to the pristine polymer. The cytocompatibility test based on hemolysis of red blood cells showed that the material lacks cytotoxicity. The investigation indicates that the material has high potential as shape memory biomaterial. 相似文献
82.
Manav R. Bhatnagar M. K. Arti Are Hjørungnes Ranjan Bose Lingyang Song 《Wireless Personal Communications》2010,54(1):69-81
In this paper, we propose high-rate space–time coding for cooperative wireless networks to reduce the overall delay incurred
in relaying signals to multiple receivers. The relay structure is optimized in order to achieve maximum SNR at the receiver
nodes. The proposed scheme provides a significant reduction in the delay required for the relaying and transmission of the
signals to the multiple receivers with a minute loss in performance. We have also shown by simulation that this loss in the
performance could be recovered by selecting more number of relays. We propose two relaying strategies for high-rate space–time
codes, which are very useful in providing high data-rate in wireless cooperative networks. 相似文献
83.
84.
85.
Rajeev Ranjan Sahay 《Water Resources Management》2012,26(13):3667-3685
The presence of transient storage zone modifies the riverine pollutant transport. In the present work, new empirical expressions for three key parameters of transient storage model (TSM), an important method for predicting concentration variation of pollutants in rivers, have been derived employing genetic algorithm on published hydraulic data on river reaches and TSM parameters. The proposed expressions use few hydraulic and geometric characteristics of rivers that are usually available. Based on various performance indices, it can be concluded that the proposed expressions predict TSM parameters more reliably in comparison to the other empirical expressions for predicting TSM parameters. 相似文献
86.
Choong Jin Yang Ph.D. Ranjan Ray Ph.D. 《JOM Journal of the Minerals, Metals and Materials Society》1989,41(9):42-45
A rapid solidification melt spinning technique has been developed to produce amorphous powders of Fe-Nd-B alloys modified with hafnium diboride. The amorphous powders are consolidated by the hot extrusion technique into bulk magnets of various cross sections. Consolidated magnets show ultrafine grain structure stabilized by ultrafine submicron hafnium diboride particles. The extruded magnets develop strong texture-induced magnetic anisotropy which leads to attractive energy product values of up to 16MGOe. Significant improvement in coercivity is also achieved due to ultrafine grain structure of the extruded magnets. 相似文献
87.
The paper reports on an investigation into the various aspects of closed die cold forging of hexagonal powder preforms, which
have been compacted and sintered from atomized powder. It is found that for certain dimensional ratios of the preform, the
die pressure is minimum. An attempt has been made determine the die pressures developed during the closed die forging of the
hexagonal powder preform by using an upper bound approach. The results so obtained are discussed critically to illustrate
the interaction of various process parameters involved and are presented graphically 相似文献
88.
The online version of the original article can be found at 相似文献
89.
Meenoti M. Patel Ranjan M. Bhatt 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1992,53(3):253-263
Alkaline peroxide pretreatment for the delignification of rice straw was optimised by varying the concentrations of H2O2 and NaOH and changing the temperature and duration of the pretreatment. Changes in the lignin content, content of total carbohydrates and weight loss were measured during the pretreatments. Maximum delignification of 62% was obtained by pretreating rice straw at 50°C for 5h with 1.5% (w/v) NaOH and 1% (v/v) H2O2, The preferential loss of hemicellulose and lignin from the straw resulted in an increase in the cellulose content of the insoluble residue after pretreatment from 47% (untreated) to 67.79% (treated). The product of this treatment is characterised by having higher cellulose digestibility than untreated rice straw. It also has use as a carbohydrate source in ruminant feed since the in-vivo digestibility by the cow increased from 56.85 % to 76.54% (P < 0.001). The treated rice straw could also be used for commercial process such as the generation of Single Cell Protein. Growth of Sporotrichum pulverulentum on treated rice straw gave a protein product of 24.41 % as compared to 3.8% on untreated rice straw. 相似文献
90.
An attempt has been made in this paper to estimate the reliability of an s-out-of-k system with non-identical component strengths when component strengths follow an exponential distribution. A further assumption is made that all the components are subjected to a common random stress which also follow an exponential distribution. Bayes and maximum likelihood estimators of such system reliability are considered. A Bayes estimate is obtained by using Lindley's approximation. Comparisons are made on the basis of efficiency and Pitman nearness probability through a Monte-Carlo study. 相似文献