全文获取类型
收费全文 | 267836篇 |
免费 | 20363篇 |
国内免费 | 13388篇 |
专业分类
电工技术 | 17730篇 |
技术理论 | 51篇 |
综合类 | 37035篇 |
化学工业 | 28792篇 |
金属工艺 | 10914篇 |
机械仪表 | 14917篇 |
建筑科学 | 37826篇 |
矿业工程 | 15224篇 |
能源动力 | 7910篇 |
轻工业 | 14910篇 |
水利工程 | 13952篇 |
石油天然气 | 11169篇 |
武器工业 | 2545篇 |
无线电 | 16935篇 |
一般工业技术 | 18752篇 |
冶金工业 | 15841篇 |
原子能技术 | 2608篇 |
自动化技术 | 34476篇 |
出版年
2024年 | 810篇 |
2023年 | 2494篇 |
2022年 | 4811篇 |
2021年 | 5783篇 |
2020年 | 6138篇 |
2019年 | 5145篇 |
2018年 | 4878篇 |
2017年 | 5992篇 |
2016年 | 7060篇 |
2015年 | 7939篇 |
2014年 | 14773篇 |
2013年 | 13349篇 |
2012年 | 17621篇 |
2011年 | 18723篇 |
2010年 | 14914篇 |
2009年 | 15580篇 |
2008年 | 14559篇 |
2007年 | 19194篇 |
2006年 | 18184篇 |
2005年 | 16000篇 |
2004年 | 13628篇 |
2003年 | 12297篇 |
2002年 | 10180篇 |
2001年 | 8655篇 |
2000年 | 7314篇 |
1999年 | 5965篇 |
1998年 | 4482篇 |
1997年 | 3961篇 |
1996年 | 3676篇 |
1995年 | 3117篇 |
1994年 | 2764篇 |
1993年 | 2061篇 |
1992年 | 1831篇 |
1991年 | 1353篇 |
1990年 | 1169篇 |
1989年 | 1036篇 |
1988年 | 838篇 |
1987年 | 575篇 |
1986年 | 431篇 |
1985年 | 356篇 |
1984年 | 336篇 |
1983年 | 243篇 |
1982年 | 223篇 |
1981年 | 167篇 |
1980年 | 130篇 |
1979年 | 111篇 |
1978年 | 63篇 |
1977年 | 73篇 |
1976年 | 55篇 |
1975年 | 55篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
罗健 《湖南冶金职业技术学院学报》2004,(1)
通过《一件小事》、《薄奠》和《骆驼祥子》三部作品中的比较分析,从“人力车夫”这一都市劳动人民的主人公形象,我们可以看到其工人阶级的友爱精神和高尚品质,同时,要清醒认识到在旧制度下劳动者的悲剧命运是无法避免的。 相似文献
992.
根据电力变压器功率损耗的分析,找到ТДГ3.15万kVA2台主变压器的功率损耗与负荷率β的函数关系,并对该2台主变压器的经济运行进行了探讨,计算出了经济运行点。 相似文献
993.
TANG Qingguo Shen Shangyue Wang Lijuan LIANG Jinsheng Ding Yan Meng Junping LI Guosheng WANG Man 《中国稀土学报(英文版)》2004,22(Z3)
The magnetic liquid was prepared with ferric salt by inorganic gel technology. The effect of the doped rare earth elements on the properties of magnetic particles was analyzed. The magnetic liquid was composed with clay mineral into magnetic mineral composites. The crystal structure and micro-morphology of the nanoparticles were studied by XRD and TEM. The results show that the crystal structure of the magnetic particles doped 0.5 % of lanthanum is more complete, and the magnetic response capability is higher with doping agent. At the same time, the possibility of the clay mineral magnetic composites as the carrier of target drug was probed. 相似文献
994.
Mehrdad Boroushaki Mohammad B. Ghofrani Caro Lucas Mohammad J. Yazdanpanah Nasser Sadati 《Nuclear Engineering and Design》2004,227(3):285-300
Improved load following capability is one of the main technical performances of advanced PWR (APWR). Controlling the nuclear reactor core during load following operation encounters some difficulties. These difficulties mainly arise from nuclear reactor core limitations in local power peaking, while the core is subject to large and sharp variation of local power density during transients. Axial offset (AO) is the parameter usually used to represent of core power peaking, in form of a practical parameter. This paper, proposes a new intelligent approach to AO control of PWR nuclear reactors core during load following operation. This method uses a neural network model of the core to predict the dynamic behavior of the core and a fuzzy critic based on the operator knowledge and experience for the purpose of decision-making during load following operations. Simulation results show that this method can use optimum control rod groups maneuver with variable overlapping and may improve the reactor load following capability. 相似文献
995.
The algorithm is divided into two steps. The first step pre-locates the blank by aligning its centre of gravity and approximate normal vector with those of destination surfaces, with largest overlap of projections of two objects on a plane perpendicular to the normal vector. The second step is optimizing an objective function by means of gradient-simulated annealing algorithm to get the best matching of a set of distributed points on the blank and destination surfaces. An example for machining… 相似文献
996.
蔬菜中的硝酸盐是一种对人体有害的化学物质,其含量比其它植物都高,人体摄入它会引起多种疾病。对近年来国内外有关光照、温度、气体、土壤中的水分和养分等对蔬菜硝酸盐积累的影响进行了综述。 相似文献
997.
Scanning transmission electron microscopy at 300 kV enables the visualization of nucleolar silver-stained structures within thick sections (3–8 μm) of Epon-embedded cells at high tilt angles (–50°; + 50°). Thick sections coated with gold particles were used to determine the best conditions for obtaining images with high contrast and good resolution. For a 6-μm-thick section the values of thinning and shrinkage under the beam are 35 to 10%, respectively. At the electron density used in these experiments (100e—/Å2/s) it is estimated that these modifications of the section stabilized in less than 10 min. The broadening of the beam through the section was measured and calculations indicated that the subsequent resolution reached 100 nm for objects localized near the lower side of 4-μm-thick sections with a spot-size of 5·6 nm. Comparing the same biological samples, viewed alternately in CTEM and STEM, demonstrated that images obtained in STEM have a better resolution and contrast for sections thicker than 3 μm. Therefore, the visualization of densely stained structures, observed through very thick sections in the STEM mode, will be very useful in the near future for microtomographic reconstruction of cellular organelles. 相似文献
998.
The vision of mass customization has driven a movement toward low volume, high variety mass customization production (MCP)
at low price. However, defect identification and defect tracking in such systems are extremely difficult because of the frequent
reconfiguration needed by the number of different part types and the interruption of the information flow about quality with
each reconfiguration of the system. It is important to quickly rebuild quality information flow with MCP system’s reconfiguration
synchronously. This paper introduces a defect tracking method based on Quality Function Deployment for every MCP system module.
A defects tracking matrix (DTM) based on the House of Quality directly connects manufacturing technologies with quality defects
inside a MCP module. Each MCP reconfiguration requires the DTMs’ rearrangement and DTM-chain is proposed. A dynamic reconstructing
algorithm synchronizes the DTM-chain with each MCP reconfiguration. A case study demonstrates the usefulness of the DTM and
DTM-chain.
相似文献
Hua WangEmail: |
999.
1000.