全文获取类型
收费全文 | 29036篇 |
免费 | 2750篇 |
国内免费 | 1326篇 |
专业分类
电工技术 | 1801篇 |
技术理论 | 4篇 |
综合类 | 1971篇 |
化学工业 | 4650篇 |
金属工艺 | 1873篇 |
机械仪表 | 1985篇 |
建筑科学 | 2274篇 |
矿业工程 | 879篇 |
能源动力 | 836篇 |
轻工业 | 2173篇 |
水利工程 | 555篇 |
石油天然气 | 2066篇 |
武器工业 | 228篇 |
无线电 | 3160篇 |
一般工业技术 | 3318篇 |
冶金工业 | 1309篇 |
原子能技术 | 320篇 |
自动化技术 | 3710篇 |
出版年
2024年 | 175篇 |
2023年 | 596篇 |
2022年 | 1077篇 |
2021年 | 1388篇 |
2020年 | 1154篇 |
2019年 | 845篇 |
2018年 | 953篇 |
2017年 | 1024篇 |
2016年 | 888篇 |
2015年 | 1280篇 |
2014年 | 1487篇 |
2013年 | 1730篇 |
2012年 | 1818篇 |
2011年 | 2010篇 |
2010年 | 1703篇 |
2009年 | 1556篇 |
2008年 | 1635篇 |
2007年 | 1533篇 |
2006年 | 1550篇 |
2005年 | 1306篇 |
2004年 | 850篇 |
2003年 | 811篇 |
2002年 | 879篇 |
2001年 | 766篇 |
2000年 | 653篇 |
1999年 | 728篇 |
1998年 | 527篇 |
1997年 | 434篇 |
1996年 | 386篇 |
1995年 | 334篇 |
1994年 | 270篇 |
1993年 | 182篇 |
1992年 | 157篇 |
1991年 | 93篇 |
1990年 | 90篇 |
1989年 | 64篇 |
1988年 | 42篇 |
1987年 | 41篇 |
1986年 | 24篇 |
1985年 | 20篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1982年 | 4篇 |
1981年 | 10篇 |
1980年 | 10篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1959年 | 1篇 |
1953年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
The application of deep learning in the field of object detection has
experienced much progress. However, due to the domain shift problem, applying an
off-the-shelf detector to another domain leads to a significant performance drop. A
large number of ground truth labels are required when using another domain to train
models, demanding a large amount of human and financial resources. In order to avoid
excessive resource requirements and performance drop caused by domain shift, this
paper proposes a new domain adaptive approach to cross-domain vehicle detection. Our
approach improves the cross-domain vehicle detection model from image space and
feature space. We employ objectives of the generative adversarial network and cycle
consistency loss for image style transfer in image space. For feature space, we align
feature distributions between the source domain and the target domain to improve the
detection accuracy. Experiments are carried out using the method with two different
datasets, proving that this technique effectively improves the accuracy of vehicle
detection in the target domain. 相似文献
23.
Jialong Tian M. Babar Shahzad Wei Wang Lichang Yin Zhouhua Jiang Ke Yang 《材料科学技术学报》2018,34(9):1671-1675
The effect of Co addition on the formation of Ni-Ti clusters in maraging stainless steel was studied by three dimensional atom probe (3DAP) and first-principles calculation. The cluster analysis based on the maximum separation approach showed an increase in size but a decrease in density of Ni-Ti clusters with increasing the Co content. The first-principles calculation indicated weaker Co-Ni (Co-Ti) interactions than Co-Ti (Fe-Ti) interactions, which should be the essential reason for the change of distribution characteristics of Ni-Ti clusters in bcc Fe caused by Co addition. 相似文献
24.
Tian Xiaoying Peng Hui Luo Xuguang Nie Shiyuan Zhou Feng Peng Xiaoyan 《International Journal of Control, Automation and Systems》2020,18(4):897-910
International Journal of Control, Automation and Systems - There is a class of typical nonlinear industrial process, which can be characterized by a first-order inertia plus pure delay model in an... 相似文献
25.
Li D. You-Song Gu Xiang-Rong Chang Fu-Shen Li Li-Jie Qiao Zhong-Zhuo Tian Fang G.-D. Qing-Shan Song 《IEEE transactions on magnetics》2003,39(6):3554-3558
We deposited Fe-Ti-N magnetic films with a high sputtering power of 7 W/cm/sup 2/. When the composition of the films was in the range of Fe-Ti(3.9 at.%)-N(8.8 at.%) to Fe-Ti(3.3 at.%)-N(13.5 at.%), the films were composed of /spl alpha/' and Ti/sub 2/N precipitates. With the addition of nitrogen, 4/spl pi/M/sub s/ became higher than that of pure iron, reaching a maximum of 23.8 kG. At the same time, H/sub c/ was reduced to a minimum of 1.12 Oe. The best films can meet the needs of the recording head in dual-element giant magnetoresistive/inductive heads, yielding high storage density (10 Gb/in/sup 2/). The incorporation of N in /spl alpha/-Fe brought about the /spl alpha/' phase with its higher saturation magnetization. Ti additions inhibited the equilibrium decomposition /spl alpha/'/spl rarr//spl alpha/+/spl gamma/'. Because H/sub C//sup D//spl prop/D/sup 6/, where D is average grain diameter, grain size control is very important. The nitrogen induces severe distortion of the /spl alpha/' lattice, which can cause the grains to break into pieces and reduce the grain size. High sputtering power also led to the formation of fine grains, with diameter in the order of 14 nm. Probably Ti/sub 2/N is preferentially precipitated on the grain boundary, pinning the grain boundary and stabilizing the grain size during high-temperature heat treatment. The temperature limit for stability of the structure and its associated low coercivity was not less than 520/spl deg/C. 相似文献
26.
在充分调研阵列声波测井分波提取方法的基础上,针对阿特拉斯公司的交叉多极子阵列声波测井(XMACⅡ)提供的单极波形信息,研究纵波时差提取及高分辨率处理方法。首先利用相关-互功谱法高精度地提取纵波时差,然后针对XMACⅡ仪器的接收阵列,研究组合子阵列的方法,形成共发射子阵列和共接收子阵列,最后利用子阵列对提取的纵波时差做高分辨率处理。处理现场实际测井资料,并将高分辨率处理成果与引进的eXpress软件处理成果、实测的国产高分辨率声波(纵波)测井曲线及岩心纵波时差对比分析,表明该方法提取的纵波时差曲线的纵向分辨率有很大提高,时差计算准确可靠,提取的单极纵波时差与国产高分辨率声波时差及岩心纵波时差的平均相对误差均小于7%。该方法具有较高的实用价值和广阔的应用前景。 相似文献
27.
28.
文章主要从实践方面介绍了向家坝水电站右岸地方还建公路北线段隧道洞口施工期边坡缺陷处理措施,并总结了几点经验,这对于以后公路隧道洞口的设计和施工,尤其是洞口边坡塌方的处理具有一定指导意义。 相似文献
29.
30.
阴,阳离子聚合物地层内凝胶化改善水驱效果的研究 总被引:9,自引:1,他引:8
研究了一杆阴离子聚合物(Ac530)和一种阳离子聚合物(Mb581)在水溶液中形成凝胶的条件和过程、凝胶化学结构、形态、稳定性和力学性能。在模拟地层的二维微观模型内观测了两种聚合物驱替渗流、相逼、形成凝胶、凝胶封堵大孔道的机理。在亲水填砂模型内测定了阴、阳离子聚合物凝胶体系降低渗透率的能力。 相似文献