全文获取类型
收费全文 | 5337篇 |
免费 | 211篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 84篇 |
综合类 | 30篇 |
化学工业 | 1532篇 |
金属工艺 | 103篇 |
机械仪表 | 95篇 |
建筑科学 | 325篇 |
矿业工程 | 23篇 |
能源动力 | 102篇 |
轻工业 | 441篇 |
水利工程 | 36篇 |
石油天然气 | 2篇 |
无线电 | 341篇 |
一般工业技术 | 1126篇 |
冶金工业 | 512篇 |
原子能技术 | 43篇 |
自动化技术 | 766篇 |
出版年
2023年 | 40篇 |
2022年 | 49篇 |
2021年 | 87篇 |
2020年 | 75篇 |
2019年 | 71篇 |
2018年 | 85篇 |
2017年 | 102篇 |
2016年 | 145篇 |
2015年 | 104篇 |
2014年 | 165篇 |
2013年 | 257篇 |
2012年 | 234篇 |
2011年 | 330篇 |
2010年 | 251篇 |
2009年 | 261篇 |
2008年 | 259篇 |
2007年 | 241篇 |
2006年 | 241篇 |
2005年 | 208篇 |
2004年 | 176篇 |
2003年 | 142篇 |
2002年 | 121篇 |
2001年 | 91篇 |
2000年 | 94篇 |
1999年 | 103篇 |
1998年 | 128篇 |
1997年 | 95篇 |
1996年 | 97篇 |
1995年 | 70篇 |
1994年 | 74篇 |
1993年 | 80篇 |
1992年 | 75篇 |
1991年 | 56篇 |
1990年 | 61篇 |
1989年 | 61篇 |
1988年 | 62篇 |
1987年 | 55篇 |
1986年 | 47篇 |
1985年 | 46篇 |
1984年 | 55篇 |
1983年 | 38篇 |
1982年 | 50篇 |
1981年 | 48篇 |
1980年 | 32篇 |
1979年 | 29篇 |
1978年 | 35篇 |
1977年 | 32篇 |
1976年 | 35篇 |
1975年 | 40篇 |
1973年 | 32篇 |
排序方式: 共有5561条查询结果,搜索用时 0 毫秒
1.
2.
Wolfgang Wendler 《电子产品世界》2006,(17):129-130
与美国同行争分夺秒抢占市场先机不同,欧洲测量仪器厂商Rohde&Schwarz公司的产品策略则相对稳健,他们的产品更专注于功能的多样化 相似文献
3.
Ohne Zusammenfassung 相似文献
4.
Types of crystallizers . In the industrial application of single mass crystallization from solution clear aims exist with regard to crystallizate qualities. To fulfil these aims, one can choose between various types of crystallizers. Magma types, i.e. agitated tank crystallizer, forced circulation and draft tube (baffle) crystallizer, as well as classifying types with the well-known Oslo-crystallizer belong to the present state of the art. The rates of secondary nucleation decrease in the same sequence as that given above and the possibilities of influencing crystal size distributions increase, and coarser crystals are produceable. 相似文献
5.
Epitaxial lamellar gallium selenide (GaSe) semiconductors have been grown on trench-patterned silicon (Si) substrates by molecular beam epitaxy. An intriguing star-like patterned morphology was identified by atomic force microscopy on these epilayers. This non-trivial feature can be correlated with the accumulation of stacking faults of two concurrent epitaxial domains around self-oriented triangular pits developed earlier on the Si(111) surface by the chemical etching. Crystallographic considerations show how the stars can be formed. 相似文献
6.
7.
8.
Minimum onset latency (Lmin) of single- and multiple-unit responses were mapped in the primary auditory cortex (AI) of barbiturate-anesthetized cats. Contralateral Lmin for multiple units was non-homogeneously distributed along the dorso-ventral/isofrequency axis of the AI. Responses with shorter latencies were more often located in the central, more sharply tuned region while longer latencies were more frequently encountered in the dorsal and ventral portions of the AI. For single units, a large scatter of Lmin values was found throughout the extent of the AI including cortical depth. The relationship between Lmin and previously reported spectral, intensity and temporal parameters was analyzed and revealed statistically significant correlations between minimum onset latency and the following response properties in some but not all studied animals: sharpness of tuning of a frequency response area 10 dB above threshold, broadband transient response, strongest response level, monotonicity of rate/level functions, dynamic range, and preferred frequency modulation sweep direction. This analysis suggests that Lmin is determined by several independent factors and that the prediction of Lmin based on relationships with other spectral and temporal response properties is inherently weak. The spatial distribution and the functional relationship between these response parameters may provide an important aspect of the time-based cortical representation of specific features in the animal's natural environment. 相似文献
9.
On the suitability of agricultural by-products for the manufacture of granular activated carbon 总被引:1,自引:0,他引:1
An investigation of several agricultural by-products revealed that their suitability for activated carbon production is not determined by general material-specific features (elemental composition) but by type-specific features. A coarse-cellular structure (as in wood), which is indicated by porosities of the raw materials higher than 35% is disadvantageous. A specific change in the properties of cokes (porosity, density, hardness) is possible by varying the conditions of pyrolysis. By rapid heating in the pyrolysis step, for instance, macroporous residues are produced. Temperature and burnoff have the greatest influence on the quality of the activated carbon during the activation step. Of the investigated materials, coconut shells yield granular activated carbon of the highest quality. The following order of suitability of raw materials for activated carbon production was established: coconut shells> peach stones> plum stones> hazelnut shells> walnut shells> cherry stones. 相似文献
10.