全文获取类型
收费全文 | 32436篇 |
免费 | 2907篇 |
国内免费 | 1506篇 |
专业分类
电工技术 | 2032篇 |
技术理论 | 2篇 |
综合类 | 2084篇 |
化学工业 | 5428篇 |
金属工艺 | 1557篇 |
机械仪表 | 2073篇 |
建筑科学 | 3118篇 |
矿业工程 | 828篇 |
能源动力 | 1019篇 |
轻工业 | 2845篇 |
水利工程 | 543篇 |
石油天然气 | 1370篇 |
武器工业 | 232篇 |
无线电 | 3771篇 |
一般工业技术 | 3940篇 |
冶金工业 | 1235篇 |
原子能技术 | 416篇 |
自动化技术 | 4356篇 |
出版年
2024年 | 161篇 |
2023年 | 591篇 |
2022年 | 1100篇 |
2021年 | 1525篇 |
2020年 | 1106篇 |
2019年 | 933篇 |
2018年 | 1057篇 |
2017年 | 1144篇 |
2016年 | 1085篇 |
2015年 | 1263篇 |
2014年 | 1681篇 |
2013年 | 2114篇 |
2012年 | 2127篇 |
2011年 | 2275篇 |
2010年 | 2151篇 |
2009年 | 2003篇 |
2008年 | 1848篇 |
2007年 | 1745篇 |
2006年 | 1622篇 |
2005年 | 1370篇 |
2004年 | 923篇 |
2003年 | 846篇 |
2002年 | 841篇 |
2001年 | 749篇 |
2000年 | 677篇 |
1999年 | 706篇 |
1998年 | 502篇 |
1997年 | 476篇 |
1996年 | 468篇 |
1995年 | 376篇 |
1994年 | 314篇 |
1993年 | 209篇 |
1992年 | 163篇 |
1991年 | 115篇 |
1990年 | 88篇 |
1989年 | 81篇 |
1988年 | 63篇 |
1987年 | 48篇 |
1986年 | 39篇 |
1985年 | 35篇 |
1984年 | 22篇 |
1983年 | 18篇 |
1982年 | 15篇 |
1981年 | 20篇 |
1980年 | 16篇 |
1979年 | 11篇 |
1977年 | 5篇 |
1962年 | 42篇 |
1961年 | 39篇 |
1960年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
对阳离子型偶联表面活性剂膨化处理的改性硝酸铵进行了电镜扫描、孔径与孔容分布、粒径分布、比表面积、抗吸湿结块性及爆炸性能的实验研究,结果表明:同普通硝酸铵相比,阳离子型偶联改性硝酸铵的晶形不规则,富含气孔;比表面积大,可达3869.56cm^2/g;95%有效孔径处于介孔范围,有较小的粒径范围,主要分布在10~1000μm范围内;并且有良好的抗吸湿结块性,改性硝酸铵的吸湿率比普通硝酸铵的吸湿率降低约60%,抗压破坏力仅为普通硝酸铵的1/6,用其制得的粉状工业炸药具有更好的物理性能和爆炸性能。 相似文献
172.
173.
In this paper, the photocatalytic activity of industrial titanium dioxide (TiO2) based nacreous pigments was researched as functional building materials for photocatalytic NO remove. Three industrial TiO2 based nacreous pigments were selected to estimate the photocatalytic activity for NO remove. This study is a good proof that pearlescent pigments can eliminate NO, and its performance is positively correlated with its titanium dioxide content. And this research will widen the application of nacreous pigments in functional building materials, and provide a new way to eliminate in door nitric oxide pollution. 相似文献
174.
175.
176.
Abstract Multi-core digital signal processors (DSPs) are widely used in wireless telecommunication, core network transcoding, industrial control, and audio/video processing technologies, among others. In comparison with general-purpose multi-processors, multi-core DSPs normally have a more complex memory hierarchy, such as on-chip core-local memory and non-cache-coherent shared memory. As a result, efficient multi-core DSP applications are very difficult to write. The current approach used to program multi-core DSPs is based on proprietary vendor software development kits (SDKs), which only provide low-level, non-portable primitives. While it is acceptable to write coarse-grained task-level parallel code with these SDKs, writing fine-grained data parallel code with SDKs is a very tedious and error-prone approach. We believe that it is desirable to possess a high-level and portable parallel programming model for multi-core DSPs. In this paper, we propose OpenMDSP, an extension of OpenMP designed for multi-core DSPs. The goal of OpenMDSP is to fill the gap between the OpenMP memory model and the memory hierarchy of multi-core DSPs. We propose three classes of directives in OpenMDSP, including 1) data placement directives that allow programmers to control the placement of global variables conveniently, 2) distributed array directives that divide a whole array into sections and promote the sections into core-local memory to improve performance, and 3) stream access directives that promote big arrays into core-local memory section by section during parallel loop processing while hiding the latency of data movement by the direct memory access (DMA) of a DSP. We implement the compiler and runtime system for OpenMDSP on PreeScale MSC8156. The benchmarking results show that seven of nine benchmarks achieve a speedup of more than a factor of 5 when using six threads. 相似文献
177.
当前以计算思维能力培养为切入点的大学计算机课程改革工作已进入一个新的阶段,如何改革计算机基础教学以适应当前形势的发展,是计算机基础教学面临的挑战。以计算思维为导向,对应用型本科院校大学计算机基础课程的目标定位、教学内容、教学过程等教学环节作改革式探索。 相似文献
178.
I. S. Kaynarskiy I. G. Orlova Ye. V. Merkulova 《Refractories and Industrial Ceramics》1961,2(1-2):59-64
Conclusions The pressing of argillaceous raw material reduced to a thermoplastic state by heating produces ultradense refractory of high quality.Standard brick made of 50% Vladimirovka kaolin, 3-1 mm, and 50% Chasov-Yar clay finer than 0.5 mm, pressed to 100 kg/cm2 and at about 1380°, containing 40% Al2O3, shows a high degree of slag resistance and spalling resistance, and has an apparent porosity of 3% bulk density 2.52 g/cm3. 相似文献
179.
Ye Wan Wenhui Guo Jin Xiao Dazhou Yan Xiong Zhao Shuhu Guo Jianhua Liu Qifan Zhong Tao Yang Yu Zhao Xin Chang Xin Gao 《中国化学工程学报》1982,28(9):2248-2255
Ultra-high-purity silicon tetrachloride (SiCl4) is demanded as an electronic-grade chemical to meet the stringent requirements of the rapidly developing semiconductor industry. The high requirement for ultra-high-purity SiCl4 has created the need for a high-efficient process for reducing energy consumption as well as satisfying product quality. In this paper, a mass of production technology of ultra-high-purity SiCl4 was successfully developed through chlorination reaction in the ultraviolet (UV)-based photo microreactor coupled with the distillation process. The influences of key operational parameters, including temperature, pressure, UV wavelength and light intensity on the product quality, especially for hydrogen-containing impurities, were quantified by the infrared transmittance of Fourier transform infrared spectroscopy (FT-IR) at 2185 cm-1 and 2160 cm-1 indicating that characteristic vibrational modes of Si—H bonds, as well as the operating conditions of distillation were also investigated as key factors for metal impurities removing. The advanced intensification of SiCl4 manufactured by the integration of photo microreactor and distillation achieves the products with superior specifications higher than the standard commercial products. 相似文献
180.
Ye Wan Wenhui Guo Jin Xiao Dazhou Yan Xiong Zhao Shuhu Guo Jianhua Liu Qifan Zhong Tao Yang Yu Zhao Xin Chang Xin Gao 《中国化学工程学报》2020,28(9):2248-2255
Ultra-high-purity silicon tetrachloride (SiCl4) is demanded as an electronic-grade chemical to meet the stringent requirements of the rapidly developing semiconductor industry. The high requirement for ultra-high-purity SiCl4 has created the need for a high-efficient process for reducing energy consumption as well as satisfying product quality. In this paper, a mass of production technology of ultra-high-purity SiCl4 was successfully developed through chlorination reaction in the ultraviolet (UV)-based photo microreactor coupled with the distillation process. The influences of key operational parameters, including temperature, pressure, UV wavelength and light intensity on the product quality, especially for hydrogen-containing impurities, were quantified by the infrared transmittance of Fourier transform infrared spectroscopy (FT-IR) at 2185 cm−1 and 2160 cm−1 indicating that characteristic vibrational modes of SiH bonds, as well as the operating conditions of distillation were also investigated as key factors for metal impurities removing. The advanced intensification of SiCl4 manufactured by the integration of photo microreactor and distillation achieves the products with superior specifications higher than the standard commercial products. 相似文献