全文获取类型
收费全文 | 54151篇 |
免费 | 6191篇 |
国内免费 | 1890篇 |
专业分类
电工技术 | 3491篇 |
综合类 | 4265篇 |
化学工业 | 9614篇 |
金属工艺 | 5410篇 |
机械仪表 | 2608篇 |
建筑科学 | 6072篇 |
矿业工程 | 927篇 |
能源动力 | 8415篇 |
轻工业 | 4108篇 |
水利工程 | 484篇 |
石油天然气 | 2494篇 |
武器工业 | 372篇 |
无线电 | 1741篇 |
一般工业技术 | 5956篇 |
冶金工业 | 3440篇 |
原子能技术 | 1069篇 |
自动化技术 | 1766篇 |
出版年
2024年 | 259篇 |
2023年 | 786篇 |
2022年 | 1532篇 |
2021年 | 1737篇 |
2020年 | 1860篇 |
2019年 | 1513篇 |
2018年 | 1358篇 |
2017年 | 1624篇 |
2016年 | 1901篇 |
2015年 | 1952篇 |
2014年 | 3296篇 |
2013年 | 3301篇 |
2012年 | 3844篇 |
2011年 | 4039篇 |
2010年 | 2967篇 |
2009年 | 3119篇 |
2008年 | 2443篇 |
2007年 | 3404篇 |
2006年 | 3053篇 |
2005年 | 2693篇 |
2004年 | 2331篇 |
2003年 | 2109篇 |
2002年 | 2011篇 |
2001年 | 1588篇 |
2000年 | 1359篇 |
1999年 | 1089篇 |
1998年 | 890篇 |
1997年 | 786篇 |
1996年 | 647篇 |
1995年 | 529篇 |
1994年 | 437篇 |
1993年 | 341篇 |
1992年 | 306篇 |
1991年 | 197篇 |
1990年 | 171篇 |
1989年 | 170篇 |
1988年 | 108篇 |
1987年 | 83篇 |
1986年 | 64篇 |
1985年 | 49篇 |
1984年 | 73篇 |
1983年 | 59篇 |
1982年 | 53篇 |
1981年 | 13篇 |
1980年 | 17篇 |
1979年 | 5篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1959年 | 29篇 |
1951年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Molecular structure and granule morphology of native and heat‐moisture‐treated pinhão starch 下载免费PDF全文
Vania Z. Pinto Khalid Moomand Nathan L. Vanier Rosana Colussi Franciene A. Villanova Elessandra R. Zavareze Loong‐Tak Lim Alvaro R. G. Dias 《International Journal of Food Science & Technology》2015,50(2):282-289
Pinhão seed is an unconventional source of starch and the pines grow up in native forests of southern Latin America. In this study, pinhão starch was adjusted at 15, 20 and 25% moisture content and heated to 100, 110 and 120 °C for 1 h. A decrease in λ max (starch/iodine complex) was observed as a result of increase in temperature and moisture content of HMT. The ratio of crystalline to amorphous phase in pinhão starch was determined via Fourier transform infra red by taking 1045/1022 band ratio. A decrease in crystallinity occurred as a result of HMT. Polarised light microscopy indicated a loss of birefringence of starch granules under 120 °C at 25% moisture content. Granule size distribution was further confirmed via scanning electron microscopy which showed the HMT effects. These results increased the understanding on molecular and structural properties of HMT pinhão starch and broadened its food and nonfood industrial applications. 相似文献
2.
Suitability,efficiency and microbiological safety of novel physical technologies for the processing of ready‐to‐eat meals,meats and pumpable products 下载免费PDF全文
Alexandros Ch. Stratakos Anastasios Koidis 《International Journal of Food Science & Technology》2015,50(6):1283-1302
Consumer studies and market reports show an increase in consumption of ready‐to‐eat (RTE) foods. Although conventional processing technologies can in most cases produce safe products, they can also lead to the degradation of nutritional compounds and negatively affect quality characteristics. Consumers strongly prefer food that is minimally processed with the maximum amount of health‐promoting substances. Novel processing technologies as pre‐ or post‐treatment decontamination methods or as substitutes of conventional technologies have the potential to produce foods that are safe, rich in nutrient content and with superior organoleptic properties. Combining novel with conventional processes can eliminate potential drawbacks of novel technologies. This review examines available scientific information and critically evaluates the suitability and efficiency of various novel thermal and nonthermal technologies in terms of microbial safety, quality as well as nutrient content on the production of RTE meals, meats and pumpable products. 相似文献
3.
垦71井区三维VSP资料波场分离方法应用研究 总被引:8,自引:5,他引:3
三维VSP资料是多偏移距VSP资料,资料中多种类型的波叠合在一起形成复杂波场。从复杂波场中分离出单一的保幅反射波波场是三维VSP波场分离的重要工作。常规二维VSP波场处理方法单一,难以适用于复杂的三维波场处理。针对三维VSP资料的波场特点,以分离上行反射P波为例,将单一波场分离方法加以适当组合,对垦71井区三维VSP实际资料进行了应用研究。结果表明,波场分离处理中叠加消去法和中值滤波相结合以及F—K滤波和中值滤波相结合的方法克服了单一方法的缺陷,波场处理后获得了波组特征明显、波场清晰单一的上行反射P波保幅波场,取得了较好的波场分离效果。 相似文献
4.
From its foundation until 2004, ETRI has registered over 1,000 US patents. This letter analyzes the characteristics of these patents and addresses the explanatory factors affecting their citation counts. For explanatory variables, research team related variables, invention specific variables, and geographical domain related variables are suggested. Zero‐altered count data models are used to test the impact of independent variables. A key finding is that technological cumulativeness, the scale of invention, outputs in the electronic field, and the degree of dependence on the US technology domain positively affect the citation counts of ETRI‐invented US patents. The magnitude of international presence appears to negatively affect the citation counts of ETRI‐invented US patents. 相似文献
5.
6.
7.
600 A IGBT开关电路及其散热系统设计 总被引:1,自引:0,他引:1
采用IGBT开关电路,对大功率电阻带进行直流脉宽调制控制,实现了内燃机车大功率直流发电机负载实验中的负载大小的连续调节。为了避免在实验过程中IGBT器件的温度过高,采用独特的双管IGBT结构和双向强迫风冷的散热系统。实验表明该电路运行稳定、可靠。 相似文献
8.
This paper presents a model of heterogenous diffusion in capillary porous materials during the process of drying. The governing heat and mass transfer equations have been established using the liquid as well as vapor flow. Two models have been presented. Model 1 does not consider the heat conduction while the model 2 has been established by considering the conduction. The developed models and the numerical solutions of the resulting differential equations can take into account the moisture and temperature dependent thermophysical properties of the product. All equations have been established in spherical coordinates but the programme written for the purpose of calculations can be used for other geometries also. Numerical calculations have been performed for gas concrete and tiles using model 1, while model 2 has been used for gas concrete only because of the lack of data for thermophysical properties of the tile. For gas concrete it was seen that conduction has only marginal effect on the drying process and the numerical predictions of the drying process were reasonably accurate. 相似文献
9.
介绍了日本川崎制铁公司技术研究所开发出的电焊钢管采用热张力减径工艺的特性 ,及这种钢管的高强度、高延性等基本特性。用这种钢管制造的汽车零部件 ,经弯曲、冲击和疲劳特性等实验 ,证明具有良好的机械加工性能 ,是制造汽车用零部件的优良材料。 相似文献
10.