全文获取类型
收费全文 | 17025篇 |
免费 | 1336篇 |
国内免费 | 658篇 |
专业分类
电工技术 | 964篇 |
技术理论 | 2篇 |
综合类 | 1116篇 |
化学工业 | 3100篇 |
金属工艺 | 864篇 |
机械仪表 | 1042篇 |
建筑科学 | 1406篇 |
矿业工程 | 556篇 |
能源动力 | 433篇 |
轻工业 | 1108篇 |
水利工程 | 282篇 |
石油天然气 | 985篇 |
武器工业 | 94篇 |
无线电 | 1936篇 |
一般工业技术 | 2168篇 |
冶金工业 | 829篇 |
原子能技术 | 291篇 |
自动化技术 | 1843篇 |
出版年
2024年 | 74篇 |
2023年 | 305篇 |
2022年 | 426篇 |
2021年 | 579篇 |
2020年 | 487篇 |
2019年 | 473篇 |
2018年 | 480篇 |
2017年 | 527篇 |
2016年 | 435篇 |
2015年 | 631篇 |
2014年 | 809篇 |
2013年 | 938篇 |
2012年 | 987篇 |
2011年 | 1005篇 |
2010年 | 891篇 |
2009年 | 984篇 |
2008年 | 901篇 |
2007年 | 881篇 |
2006年 | 933篇 |
2005年 | 784篇 |
2004年 | 591篇 |
2003年 | 545篇 |
2002年 | 558篇 |
2001年 | 525篇 |
2000年 | 444篇 |
1999年 | 530篇 |
1998年 | 373篇 |
1997年 | 347篇 |
1996年 | 350篇 |
1995年 | 283篇 |
1994年 | 261篇 |
1993年 | 162篇 |
1992年 | 126篇 |
1991年 | 91篇 |
1990年 | 74篇 |
1989年 | 67篇 |
1988年 | 50篇 |
1987年 | 34篇 |
1986年 | 20篇 |
1985年 | 15篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 2篇 |
1977年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
余璆 《上海工程技术大学学报》2004,18(2):127-130
介绍了实现指纹签到系统中高级语言Visual Basic对底层二进制数据的读取方法,数据的存放方式。详细讲述了用Visual Basic编程的关键技术和方法。同时给出了指纹签到系统的使用效果和应用前景。 相似文献
42.
用正电子湮没研究含砷α黄铜的脱锌机制 总被引:3,自引:0,他引:3
分别测量了含0.00、0.01、0.03、0.05、007、0.10wt%As的68wt%Cu-Zn合金在1%CuCl2水溶液中脱锌后的正电子寿命谱。讨论了黄铜脱锌及砷抑制脱锌的空位体扩散机制。 相似文献
43.
Wei Li Wenxi Tian Suizheng Qiu Guanghui Su Hong Jiao Yunqing Bai Hongli Chen Yican Wu 《Fusion Engineering and Design》2013,88(5):286-294
China has proposed the dual-functional lithium-lead (DFLL) tritium breeding blanket concept for testing in ITER as a test blanket module (TBM), to demonstrate the technologies of tritium self-sufficiency, high-grade heat extraction and efficient electricity production which are needed for DEMO and fusion power plant. Safety assessment of the TBM and its auxiliary system should be conducted to deal with ITER safety issues directly caused by the TBM system failure during the design process. In this work, three potential initial events (PIEs) – in-vessel loss of helium (He) coolant and ex-vessel loss of He coolant and loss of flow without scram (LOFWS) – were analyzed for the TBM system with a modified version of the RELAP5/MOD3 code containing liquid lithium-lead eutectic (LiPb). The code also comprised an empirical expression for MHD pressure drop relevant to three-dimensional (3D) effect, the Lubarsky–Kaufman convective heat transfer correlation for LiPb flow and the Gnielinski convective heat transfer correlation for He flow. Since both LiPb and He serve as TBM coolants, the LiPb and He ancillary cooling systems were modeled to investigate the thermal-hydraulic characteristic of the TBM system and its influence on ITER safety under those accident conditions. The TBM components and the coolants flow within the TBM were simulated with one-dimensional heat structures and their associated hydrodynamic components. ITER enclosures including vacuum vessel (VV), port cell and TCWS vault were also covered in the model for accident analyses. Through this best estimate approach, the calculation indicated that the current design of DFLL-TBM and its auxiliary system meets the thermal-hydraulic and safety requirements from ITER. 相似文献
44.
本文介绍了放射性污染石墨固定床式焚烧处理的可行性试验研究及石墨液压破碎机研制结果。小试验和扩大试验结果表明 ,采用固定床式焚烧石墨 ,并将燃气引入燃烧炉中二次燃烧这一方案是可行的 ,空气流速在 0 .0 65~ 0 .0 7m/s范围内 ,石墨炉的处理强度为 30 kg/m2 · h左右 ,烟气中 CO浓度小于0 .1% ,残渣量小于 1% ,且二次燃烧不需要或只需少量辅助燃料助燃。所研制的液压破碎机 ,性能良好 ,产生的细粉量少 ,可以满足石墨焚烧前处理的需求。 相似文献
45.
本文整理出巴米扬山谷遗址群的年代学证据,旨在重现大佛的历史与图像地位。首先介绍了巴米扬山谷遗址群的研究方法和年代阶段,接着讨论玄奘所见所录的大佛的原始配置,最后将三尊佛像放入其原始的图像志语境中去考查,认为涅檗像原应位于38米大佛和55米大佛之间。后者为宝装焰肩佛,其神格应为燃灯佛;38米大佛为释迦佛。而巡礼者所遵循的应是燃灯佛-释迦佛-涅粲佛-弥勒佛的绕拜顺序。 相似文献
46.
47.
对基于离散傅里叶变换(DFT)信号处理方式的柯氏质量流量计来说,影响其精度的关键问题是如何实现信号的整周期采样。提出了一种全新的方法,用采样率固定不变的采样数据,通过软件实时地确定信号的频率并且实现信号整周期重新采样。实验结果表明该方法在求取相位差时具有极高的精度。 相似文献
48.
49.
Fei Li Heqiu Zhang Lizhong Hu Yingmin Luo Yu Zhao Yu Qiu Jiuyu Ji Lunlun Yue 《Journal of Materials Science: Materials in Electronics》2013,24(12):4812-4816
One-dimensional (1D) ZnO microwires were successfully synthesized by chemical vapor deposition and their structural and morphological properties were analyzed by X-ray diffraction and scanning electron microscopy, demonstrating that the microwires were single crystalline with perfect hexagonal structure and smooth surface. Using these 1D microstructures, we fabricated a novel ZnO-based ethanol gas sensor. Operating at room temperature, the sensor was found to have good sensing characteristics. The reliability and stability of the sensor could be improved by connecting multiple 1-wire devices (1-WD) in parallel into a multi-wires device. In interior natural lighting environment and under 3 V bias, the response and recovery time of the 1-WD to 200 ppm ethanol gas were <10 s and about 300 s, respectively, and the minimum and maximum detection limit were about 2 and 200 ppm, respectively. A sensing model was proposed for discussing the performance of the sensor. The simplicity in fabrication, low power consumption and low cost make the sensor suitable for practical application in many fields, especially in identifying driving under the influence and chemical industry monitoring. 相似文献
50.
Jun Yan Yigang Chen Qingling Yuan Song Yu Wencai Qiu Chengguang Yang Zhigang Wang Jianfeng Gong Kaixing Ai Qi Zheng Jianan Li Shaoxiang Zhang Xiaonong Zhang 《Journal of materials science. Materials in medicine》2013,24(6):1515-1525
To evaluate the ability of Mg–6Zn to replace titanium nails in the reconstruction of the intestinal tract in general surgery, we compared the Mg–6Zn and titanium implants with respect to their effects on rat’s intestinal tract by biochemical, radiological, pathological and immunohistochemical methods. The results indicated that Mg–6Zn implants started to degrade at the third week and disintegrate at the fourth week. No bubbles appeared, which may be associated with intestinal absorption of the Mg–6Zn implants. Pathological analyses (containing liver, kidney and cecum tissues) and biochemical measurements, including serum magnesium, creatinine, blood urea nitrogen, glutamic–pyruvic–transaminase and glutamic–oxaloacetic–transaminase proved that degradation of Mg–6Zn did not harm the important organs, which is an improvement over titanium implants. Immunohistochemical results showed that Mg–6Zn could enhance the expression of transforming growth factor-β1. Mg–6Zn reduced the expression of tumor necrosis factor at different stages. In general, our study demonstrates that the Mg–6Zn alloy had good biocompatibility in vivo and performed better than titanium at promoting healing and reducing inflammation. It may be a promising candidate for stapler pins in intestinal reconstruction. 相似文献