全文获取类型
收费全文 | 207638篇 |
免费 | 1653篇 |
国内免费 | 416篇 |
专业分类
电工技术 | 3556篇 |
综合类 | 157篇 |
化学工业 | 31935篇 |
金属工艺 | 10274篇 |
机械仪表 | 7015篇 |
建筑科学 | 4027篇 |
矿业工程 | 2165篇 |
能源动力 | 4666篇 |
轻工业 | 12984篇 |
水利工程 | 3002篇 |
石油天然气 | 7758篇 |
武器工业 | 24篇 |
无线电 | 21642篇 |
一般工业技术 | 45304篇 |
冶金工业 | 34386篇 |
原子能技术 | 6627篇 |
自动化技术 | 14185篇 |
出版年
2021年 | 2116篇 |
2019年 | 2119篇 |
2018年 | 3684篇 |
2017年 | 3724篇 |
2016年 | 4035篇 |
2015年 | 2254篇 |
2014年 | 3796篇 |
2013年 | 8742篇 |
2012年 | 5686篇 |
2011年 | 7224篇 |
2010年 | 5861篇 |
2009年 | 6491篇 |
2008年 | 6616篇 |
2007年 | 6495篇 |
2006年 | 5570篇 |
2005年 | 5117篇 |
2004年 | 4631篇 |
2003年 | 4554篇 |
2002年 | 4368篇 |
2001年 | 4478篇 |
2000年 | 4187篇 |
1999年 | 4200篇 |
1998年 | 10186篇 |
1997年 | 7182篇 |
1996年 | 5506篇 |
1995年 | 4131篇 |
1994年 | 3598篇 |
1993年 | 3840篇 |
1992年 | 2984篇 |
1991年 | 2996篇 |
1990年 | 2892篇 |
1989年 | 2852篇 |
1988年 | 2864篇 |
1987年 | 2508篇 |
1986年 | 2568篇 |
1985年 | 2854篇 |
1984年 | 2687篇 |
1983年 | 2554篇 |
1982年 | 2301篇 |
1981年 | 2269篇 |
1980年 | 2348篇 |
1979年 | 2359篇 |
1978年 | 2382篇 |
1977年 | 2487篇 |
1976年 | 2876篇 |
1975年 | 2188篇 |
1974年 | 2068篇 |
1973年 | 2166篇 |
1972年 | 1940篇 |
1971年 | 1755篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Hongxuan Zhang Venkatesha S. Minahan R. Sherman D. Oweis Y. Natarajan A. Thakor N.V. 《IEEE engineering in medicine and biology magazine》2006,25(4):39-45
Intraoperative neurological monitoring (INM) is the evaluation of the nervous system within the operating room (OR) environment. In this paper, the INM system is tested in a clinical setting in comparison with conventional somatosensory evoked potential (SEP) monitoring. The study results demonstrate the capability of the INM system in extracting clearer and more stable SEP signals. The high SNR of SEP signals collected in various clinical environments, including the OR, makes the INM system a robust platform for continuous monitoring. While the current use of EP monitoring is limited to intermittent analysis by a highly trained clinical neurophysiologist, the authors believe in changing this paradigm by developing continuous monitoring systems, such as the INM system, capable of automated quantitative EP analysis. This noninvasive monitoring modality will allow for a wider range of use in clinical practice. Based on volunteer and clinical patient studies, the INM monitoring system demonstrates much greater reliability and accuracy via the artifact rejection and denoising strategies. It provides more strategic filtering options for different situations under which the clinical SEP response signal could be greatly contaminated and distorted. Furthermore, the INM system offers a promising approach to signal extraction in real-time monitoring during SEP research. 相似文献
92.
Morosi S. Marabissi D. Enrico Del Re Fantacci R. Del Santo N. 《Power Delivery, IEEE Transactions on》2006,21(4):1892-1897
This paper deals with a variable rate discrete multitone modulation system for broadband power-line communications, based on the bit-loading algorithm proposed by Leke and Cioffi. In the proposed system a suitable least mean square channel estimator is considered, which is based on the insertion of a training sequence (TS). The proposed approach will be compared with the ideal channel estimates, showing its effectiveness. Moreover, different TS lengths will be compared. The system performance, expressed in terms of bit rate and bit-error rate, is derived by simulation with and without estimation errors. The propagation environment has been assumed as a frequency-selective multipath fading channel with additive colored Gaussian noise, according to the in-building networks model. 相似文献
93.
Four selected azo dyes (acid orange 6, acid orange 7, methyl orange and methyl red) were completely decolourised in the presence of anaerobic granular sludge, while only methyl red was degraded in aerobic conditions using a conventional activated sludge. Additional experiments with culture broth devoid of cells showed that anaerobic decolourisation of azo dyes was performed by extracellular reducing agents produced by anaerobic bacteria. This was further confirmed by abiotic experiments with sulphide and NADH. The presence of redox mediators such as riboflavin led to dramatic acceleration of the anaerobic biodecolourisation process. The azo dye reduction products were found to be sulphanilic acid and 4-aminoresorcinol for acid orange 6; sulphanilic acid and 1-amino-2-naphthol for acid orange 7; N,N-dimethyl-1,4-phenylenediamine and sulphanilic acid for methyl orange; and N,N-dimethyl-1,4-phenylenediamine and anthranilic acid for methyl red. Anaerobic toxicity assays showed that the azo dyes were more toxic than their breakdown products (aromatic amines), except 1-amino-2-naphthol. In the presence of activated sludge, only anthranilic acid was completely mineralised while sulphanilic acid was persistent. 4-aminoresorcinol, 1-amino-2-naphthol and N,N-dimethyl-1,4-phenylenediamine underwent autooxidation in aerobic conditions yielding coloured polymeric products. On the contrary, in the presence of granular methanogenic sludge, 4-aminoresorcinol, 1-amino-2-naphthol and anthranilic acid were quantitatively methanised, sulphanilic acid was partially (70%) mineralised while N,N-dimethyl-1,4-phenylenediamine was only demethylated producing 1,4-phenylenediamine as an end product. 相似文献
94.
95.
Translated from Atomnaya Énergiya, Vol. 66, No. 5, pp. 321–324, May, 1989. 相似文献
96.
Translated from Atomnaya Énergiya, Vol. 66, No. 3, pp. 213–215, March, 1989. 相似文献
97.
A. I. Gorelov A. I. Efanov V. G. Nazaryan V. V. Postnikov A. N. Sviridenkov V. V. Shevchenko 《Atomic Energy》1989,66(2):90-96
Translated from Atomnaya Énergiya, Vol. 66, No. 2, pp. 81–85, February, 1989. 相似文献
98.
N. V. Lubkov 《Automation and Remote Control》2002,63(9):1524-1532
Calculation relations were obtained and step-by-step procedures were developed in order to model failures of given multiplicities in system elements and random sojourns of the semi-Markovian process in various states, as well as to construct variational series. These procedures can be used to design simulation systems of various destinations. 相似文献
99.
A group parity prediction scheme which can be used for concurrent testing of linear feedback shift register circuits is described. 相似文献
100.
A. T. Mamadalimov B. L. Oksegendler Sh. O. Otazhonov B. É. Turaev T. A. Usmanov N. K. Khakimova Zh. A. Kadirov 《Technical Physics Letters》2002,28(7):581-583
The photoelectric properties of cotton fibers treated with iodine were studied in the fundamental absorption range. The samples exhibit a sublinear illumination-current characteristic and a long-term relaxation of photoconductivity (PC) after UV irradiation (hν=5 eV) of the iodine-doped fibers. A PC mechanism is proposed which explains both the nonlinear variation of photocurrent with illumination intensity and the PC decay according to a bimolecular recombination law after UV irradiation of the iodine-doped fiber in the fundamental absorption range. 相似文献