全文获取类型
收费全文 | 200620篇 |
免费 | 2353篇 |
国内免费 | 615篇 |
专业分类
电工技术 | 3474篇 |
综合类 | 150篇 |
化学工业 | 29239篇 |
金属工艺 | 8084篇 |
机械仪表 | 6089篇 |
建筑科学 | 4815篇 |
矿业工程 | 1304篇 |
能源动力 | 5188篇 |
轻工业 | 17205篇 |
水利工程 | 2301篇 |
石油天然气 | 4047篇 |
武器工业 | 8篇 |
无线电 | 23119篇 |
一般工业技术 | 40280篇 |
冶金工业 | 37316篇 |
原子能技术 | 5090篇 |
自动化技术 | 15879篇 |
出版年
2021年 | 1637篇 |
2019年 | 1590篇 |
2018年 | 2611篇 |
2017年 | 2687篇 |
2016年 | 2810篇 |
2015年 | 1823篇 |
2014年 | 3110篇 |
2013年 | 9007篇 |
2012年 | 5114篇 |
2011年 | 7095篇 |
2010年 | 5636篇 |
2009年 | 6395篇 |
2008年 | 6484篇 |
2007年 | 6557篇 |
2006年 | 5605篇 |
2005年 | 5258篇 |
2004年 | 5018篇 |
2003年 | 4905篇 |
2002年 | 4543篇 |
2001年 | 4666篇 |
2000年 | 4586篇 |
1999年 | 4735篇 |
1998年 | 11397篇 |
1997年 | 8135篇 |
1996年 | 6420篇 |
1995年 | 4684篇 |
1994年 | 4282篇 |
1993年 | 4086篇 |
1992年 | 3228篇 |
1991年 | 3077篇 |
1990年 | 2875篇 |
1989年 | 2958篇 |
1988年 | 2835篇 |
1987年 | 2408篇 |
1986年 | 2310篇 |
1985年 | 2717篇 |
1984年 | 2508篇 |
1983年 | 2350篇 |
1982年 | 2095篇 |
1981年 | 2213篇 |
1980年 | 2033篇 |
1979年 | 2127篇 |
1978年 | 2120篇 |
1977年 | 2368篇 |
1976年 | 3196篇 |
1975年 | 1834篇 |
1974年 | 1761篇 |
1973年 | 1772篇 |
1972年 | 1443篇 |
1971年 | 1340篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
931.
932.
933.
934.
935.
936.
937.
938.
Madarasz RL Thompson WB 《IEEE transactions on pattern analysis and machine intelligence》1985,(6):713-717
An important application of machine vision systems is the recognition of known three-dimensional objects. A major difficulty arises when two or more objects project the same or similar two-dimensional image, often resulting in misclassification and degradation of system performance. The changes in images which result from the motion of objects provide a source of three-dimensional information which can greatly aid the classification process, but this three-dimensional analysis is computationally complex and subject to many sources of error. This work develops a methodology which utilizes the information derived from the apparent changes in object features over time to facilitate the recognition task, without the need to actually recover the three-dimensional structure of the objects under view. The basic approach is to generate a ``feature signature' by combining the feature measurements of the individual regions in a long sequence of images. The static information in the individual frames is analyzed along with the temporal information from the entire sequence. These techniques are particularly applicable in situations where static image processing methods cannot discriminate between ambiguous objects. Two example implementations are presented to illustrate the application of the techniques of object recognition using motion information. 相似文献
939.
N N Tupitsyn E B Mechetner A Iu Baryshnikov E N Rozinova 《Eksperimental?nai?a onkologii?a》1987,9(4):30-34
Expression of erythroid antigens identifying with the use of monoclonal antibodies (mab) HAE3 and HAE9 was studied in 333 patients with different types of hemoblastoses. Frequency of erythroid variants based on the reaction with mab was 5.7%. In 2.4% of cases erythroid markers were the only indication on the nature of leukemia. In 2.7% of cases the types of leukemia were accounted for as "mixed" ones, i.e. erythrolymphoid and erythromyeloid variants. Only in 0.6% of cases erythroid variant was detected by the morphological criteria. 相似文献
940.
The paper reports on an investigation of the electric resistance as a function of temperatureT, magnetic fieldH, and applied voltageV in granular indium films when approaching the metal-insulator transition (MIT) due to increased thickness of the oxide layers between granules. The dependences are shown to be governed atT5 K by competition of the hopping conductivity and the Josephson tunneling of electrons, sometimes giving rise to a resistance minimum inR(T) associated with superconductivity. It was also found that even when the intergranular Josephson tunneling is totally suppressed, transition of granules to the superconducting state influences essentially the dependencesR(T, H), changing the functional form ofR(T) and resulting in anomalously high negative magnetoresistance. This is shown to stem from the change of the character of activated electron tunneling as the granules become superconducting. 相似文献