全文获取类型
收费全文 | 378970篇 |
免费 | 3637篇 |
国内免费 | 600篇 |
专业分类
电工技术 | 6401篇 |
综合类 | 371篇 |
化学工业 | 60871篇 |
金属工艺 | 16861篇 |
机械仪表 | 11898篇 |
建筑科学 | 7982篇 |
矿业工程 | 2946篇 |
能源动力 | 7450篇 |
轻工业 | 31846篇 |
水利工程 | 4754篇 |
石油天然气 | 11930篇 |
武器工业 | 42篇 |
无线电 | 36614篇 |
一般工业技术 | 76235篇 |
冶金工业 | 68744篇 |
原子能技术 | 11280篇 |
自动化技术 | 26982篇 |
出版年
2021年 | 3256篇 |
2019年 | 3189篇 |
2018年 | 5683篇 |
2017年 | 5751篇 |
2016年 | 6151篇 |
2015年 | 3554篇 |
2014年 | 6173篇 |
2013年 | 15325篇 |
2012年 | 9487篇 |
2011年 | 12516篇 |
2010年 | 10041篇 |
2009年 | 11118篇 |
2008年 | 11528篇 |
2007年 | 11645篇 |
2006年 | 10163篇 |
2005年 | 9120篇 |
2004年 | 8688篇 |
2003年 | 8462篇 |
2002年 | 8517篇 |
2001年 | 8421篇 |
2000年 | 8128篇 |
1999年 | 7956篇 |
1998年 | 18567篇 |
1997年 | 13268篇 |
1996年 | 10146篇 |
1995年 | 7847篇 |
1994年 | 7003篇 |
1993年 | 6981篇 |
1992年 | 5521篇 |
1991年 | 5299篇 |
1990年 | 5604篇 |
1989年 | 5398篇 |
1988年 | 5221篇 |
1987年 | 4716篇 |
1986年 | 4826篇 |
1985年 | 5295篇 |
1984年 | 5049篇 |
1983年 | 4693篇 |
1982年 | 4414篇 |
1981年 | 4626篇 |
1980年 | 4418篇 |
1979年 | 4520篇 |
1978年 | 4671篇 |
1977年 | 4957篇 |
1976年 | 6433篇 |
1975年 | 4225篇 |
1974年 | 4161篇 |
1973年 | 4292篇 |
1972年 | 3772篇 |
1971年 | 3439篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
91.
PCR-based procedures in detection and DNA-fingerprinting of Salmonella from samples of animal origin
A. del Cerro S. M. Soto E. Landeras M. A. Gonzlez-Hevia J. A. Guijarro M. C. Mendoza 《Food microbiology》2002,19(6):567
The usefulness of selected PCR-protocols for the detection of Salmonella in 117 samples of animal origin (17 raw minced meat, 27 raw chicken meat, 8 raw sausages, and 25 egg samples, as well as 18 poultry faecal, and caecal swabs samples) and DNA-fingerprinting typing is shown. To establish an accurate PCR-procedure for Salmonella detection the following parameters were evaluated: two pre-PCR concentration procedures, centrifugation and immunomagnetic separation (IMS) using Dynabeads anti- Salmonella; the specificity and sensitivity of 10 sets of primers; and different conditions of the amplification reaction. In light of the results obtained from the use of PCR-based procedures alone or in combination with conventional methods, the following findings can be underlined: First, IMS is more efficient than centrifugation in the recovery of Salmonella. Second, the selected IMS/PCR-detection protocol is less time-consuming (45 h) than the IMS/culture procedure (90 h), and a good concordance between them was found when the Kappa coefficient was calculated (0·87). Third, PCR-ribotyping technique showed a very low discrimination power, being able to differentiate only three profiles. Fourth, RAPD technique using specific primers supports previous works in which it was proposed as a simple and useful tool for discriminating isolates between and within serotypes. Fifth, The efficiency, rapidity, and flexibility of the PCR-protocols applied were high, and they can be performed using two PCR-programs and the same basic equipment. 相似文献
92.
93.
I. N. Polandov V. K. Novik O. K. Gulish B. P. Bogomolov V. B. Morozov 《Measurement Techniques》1989,32(9):888-890
Translated from Izmeritel'naya Tekhnika, No. 9, pp. 34–35, September, 1989. 相似文献
94.
95.
We have designed, developed, and tested a very promising thermal image analysis method for polygraph testing. The method achieved a correct classification rate of CCR= 84% on the test population to our avail. This method, once refined, can serve as an additional channel for increasing the reliability and accuracy of traditional polygraph examination. We extract subtle facial temperature fluctuation patterns through nonlinear heat transfer modeling. The modeling transforms raw thermal data to blood flow rate information. Then, we use the slope of the average periorbital blood flow rate as the feature of a binary classification scheme. The results come to support our previous laboratory findings about the importance of periorbital blood flow in anxious states. 相似文献
96.
97.
98.
V. L. Ozol' L. F. Kandyba N. T. Bychenkov L. A. Zbarskii B. E. Koropov 《Metallurgist》1989,33(8):156-156
Lenin Dnepropetrovsk Pipe Plant. Translated from Metallurg, No. 8, p. 39, August, 1989. 相似文献
99.
A. M. Pristrem N. I. Danilovich V. A. Labunov 《Journal of Engineering Physics and Thermophysics》1987,53(6):1464-1472
By using integral transform methods, an approach is developed to the solution of a problem on the temprature distribution in multilayer structures heated by cw scanning laser radiation, with phase transitions in the layers taken into account.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 53, No. 6, pp. 1000–1010, December, 1987. 相似文献
100.