全文获取类型
收费全文 | 912071篇 |
免费 | 11235篇 |
国内免费 | 2936篇 |
专业分类
电工技术 | 16586篇 |
综合类 | 1492篇 |
化学工业 | 139871篇 |
金属工艺 | 35942篇 |
机械仪表 | 28013篇 |
建筑科学 | 21701篇 |
矿业工程 | 5683篇 |
能源动力 | 23762篇 |
轻工业 | 75450篇 |
水利工程 | 10305篇 |
石油天然气 | 19516篇 |
武器工业 | 140篇 |
无线电 | 101742篇 |
一般工业技术 | 180165篇 |
冶金工业 | 164891篇 |
原子能技术 | 20828篇 |
自动化技术 | 80155篇 |
出版年
2021年 | 8346篇 |
2020年 | 6172篇 |
2019年 | 7839篇 |
2018年 | 13215篇 |
2017年 | 13452篇 |
2016年 | 14089篇 |
2015年 | 9205篇 |
2014年 | 15336篇 |
2013年 | 41499篇 |
2012年 | 23958篇 |
2011年 | 32901篇 |
2010年 | 26029篇 |
2009年 | 29349篇 |
2008年 | 29900篇 |
2007年 | 29573篇 |
2006年 | 25851篇 |
2005年 | 23733篇 |
2004年 | 23057篇 |
2003年 | 22626篇 |
2002年 | 21825篇 |
2001年 | 21241篇 |
2000年 | 20125篇 |
1999年 | 20428篇 |
1998年 | 48909篇 |
1997年 | 35136篇 |
1996年 | 27403篇 |
1995年 | 21077篇 |
1994年 | 18754篇 |
1993年 | 18613篇 |
1992年 | 14173篇 |
1991年 | 13536篇 |
1990年 | 13183篇 |
1989年 | 12828篇 |
1988年 | 12185篇 |
1987年 | 10973篇 |
1986年 | 10784篇 |
1985年 | 12222篇 |
1984年 | 11114篇 |
1983年 | 10431篇 |
1982年 | 9667篇 |
1981年 | 9761篇 |
1980年 | 9385篇 |
1979年 | 9221篇 |
1978年 | 9052篇 |
1977年 | 10236篇 |
1976年 | 13070篇 |
1975年 | 8050篇 |
1974年 | 7804篇 |
1973年 | 7933篇 |
1972年 | 6627篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
991.
The Uniform Covering by Probabilistic Rejection (UCPR) algorithm was used, in conjunction with the Soil and Water Assessment Tool (SWAT) model, to identify P loads from point source and nonpoint source polluters in the upper Etowah River basin (UERB) in Georgia. The key findings of the research are as follows. The mean absolute error was preferred over the root mean square error as a search criterion for the UCPR algorithm when water quality observations are scarce. The undocumented P load from point sources in the UERB was consistently estimated as about 43 kg/d by the proposed method; but the method was not able to identify the broiler litter application rate to the poultry/beef operation pastures. Point sources (both documented and undocumented), poultry/beef operation pastures, and forests are the three major contributors of P. During 1992-1996, on average they accounted for 36.4, 31.7, and 17.2% of P load from the UERB, respectively. 相似文献
992.
993.
994.
995.
Two techniques for the design and fast search of a vector quantiser codebook are proposed. These classify speech data vectors according to (i) the sign and (ii) the slope between successive samples. With both techniques the performance obtained is superior to that obtained from a conventional gain/shape vector quantiser and comparable to that of a full search vector quantiser. A major attraction of both approaches is that they significantly reduce the number of computations required for the codebook search. 相似文献
996.
The effects of adding sodium hydroxide (NaOH), separately or in combinastion with various inorganic phosphates, on meat emulsion characteristics were studied. In comparing the addition of either NaPP or NaOH, 0.075% NaOH resulted in a higher raw emulsion pH and greater solubilized protein than 0.30% NaPP, but NaPP resulted in a more stable emulsion. The combination of 0.075% NaOH and 0.30% NaPP resulted in a soluble protein level less than when the ingredients were added individually and only slightly higher than if neither were present. The addition of NaOH (at 1 part NaOH to 4 parts phosphate) decreased cooked yields. With NaAPP and NaPP, NaOH reduced yields below that of the control. 相似文献
997.
Th. Hilbert und P. B?ttcher 《Holz als Roh- und Werkstoff》1985,43(6):242
Ohne Zusammenfassung 相似文献
998.
S.D. Holdsworth 《Journal of food engineering》1985,4(2):89-116
The mathematical methods for optimising the effects of heat processing food products are reviewed in relation to microbial destruction, nutrient destruction, cooking value and loss of quality. Some data are presented for the kinetics of the various thermal effects. The results obtained by various workers are presented with particular reference to nutrient retention. 相似文献
999.
D G Kindack A MacIntosh M Lebelle G Carignan S Sved 《Food Additives & Contaminants》1991,8(6):737-748
During surveillance of hog carcasses from Manitoba for antibiotic residues by the Health of Animals Laboratory, Agriculture Canada, Saskatoon, an unknown substance was found which produced tetracycline-like results with the methods used. This same substance was found in an implicated swine feed premix. Using various HPLC systems and columns, UV spectroscopy, reverse-phase TLC, and mass spectrometry, the substance was isolated from the feed premix, and identified as lumichrome, a photodegradation product of riboflavin. Traces of the same substance were found in riboflavin standard. Analysis of swine kidney, previously found to contain the unknown, showed the same substance was present at a level of about 1 ppm. 相似文献
1000.
A. O. Skomorokhov V. N. Kutinsky M. T. Slepov 《Pattern Recognition and Image Analysis》2006,16(1):85-88
The paper describes a few modifications of the classification tree construction algorithm that have proved to be useful for
solving tasks of noise spectra processing with reference to NPP diagnostics.
The article was translated by the authors. 相似文献