全文获取类型
收费全文 | 16712篇 |
免费 | 1513篇 |
国内免费 | 1118篇 |
专业分类
电工技术 | 601篇 |
综合类 | 847篇 |
化学工业 | 6147篇 |
金属工艺 | 1373篇 |
机械仪表 | 557篇 |
建筑科学 | 341篇 |
矿业工程 | 189篇 |
能源动力 | 478篇 |
轻工业 | 977篇 |
水利工程 | 66篇 |
石油天然气 | 1269篇 |
武器工业 | 162篇 |
无线电 | 1871篇 |
一般工业技术 | 1405篇 |
冶金工业 | 822篇 |
原子能技术 | 438篇 |
自动化技术 | 1800篇 |
出版年
2024年 | 109篇 |
2023年 | 407篇 |
2022年 | 920篇 |
2021年 | 996篇 |
2020年 | 731篇 |
2019年 | 480篇 |
2018年 | 388篇 |
2017年 | 503篇 |
2016年 | 574篇 |
2015年 | 563篇 |
2014年 | 752篇 |
2013年 | 921篇 |
2012年 | 929篇 |
2011年 | 1300篇 |
2010年 | 871篇 |
2009年 | 1005篇 |
2008年 | 907篇 |
2007年 | 983篇 |
2006年 | 931篇 |
2005年 | 746篇 |
2004年 | 578篇 |
2003年 | 530篇 |
2002年 | 478篇 |
2001年 | 464篇 |
2000年 | 397篇 |
1999年 | 355篇 |
1998年 | 269篇 |
1997年 | 222篇 |
1996年 | 185篇 |
1995年 | 163篇 |
1994年 | 134篇 |
1993年 | 120篇 |
1992年 | 108篇 |
1991年 | 73篇 |
1990年 | 67篇 |
1989年 | 26篇 |
1988年 | 24篇 |
1987年 | 29篇 |
1986年 | 14篇 |
1985年 | 20篇 |
1984年 | 17篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1974年 | 4篇 |
1959年 | 3篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
62.
63.
Infants' sensitivity to optical flow for controlling sitting and standing was tested using a "moving room" in which all of the walls moved together, or only the side walls or front wall moved. Two questions motivated this research. (a) is the optical flow necessary for inducing postural compensations spatially distributed in the optic array? (b) Do visually induced compensations follow a developmental progression, or alternatively, emerge all at once? Experiment 1 was designed to test postural compensations by 14-month-old infants capable of standing in the moving room. Experiment 2 was designed to test postural compensations by 5- to 9-month-old infants who were passively supported while sitting in the moving room. The results revealed that partial flow is generally sufficient for inducing postural compensations, but that the amplitude and consistency of the response depend on the location of the flow in the optic array. In addition, there was evidence suggesting that compensatory responses become increasingly systematic during the second half of the first year. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
64.
65.
随着移动通信技术的革新及互联网产业的迅猛发展,以移动互联网为代表的移动数据业务呈现出快速增长的势头,HTML5的出现给移动互联网带来了新的变革。本文首先介绍了移动互联网的发展现状、业务模式,HTML5的发展与技术特点,然后对HTML5在移动互联网中的应用进行了阐述,并列举了部分案例。 相似文献
66.
纯电动汽车车载动力电池是其唯一的动力源且很有限,辅助设备消耗的电能减少了纯电动汽车的续驶里程,尤其是空调,所以开发高效的纯电动汽车空调系统是纯电动汽车能够被市场接受的关键。将纯电动汽车顶盖布满太阳电池,可以使空调系统的制冷能力增强,同时还能增加纯电动汽车的行驶距离。对小型纯电动汽车的太阳能辅助空调系统进行研究,设计出适合该空调的自动控制系统,可为纯电动汽车创造出一个更加舒适的驾驶和乘座环境。 相似文献
67.
对AB5型LaxMm1-x(NiMnSiAlFe)49(x=0,0.45,0.75,1.00,摩尔分数)贮氢合金进行了快淬处理,研究了La含量及快淬工艺对合金微观结构及电化学循环稳定性的影响.结果表明:La含量的增加对铸态合金的循环稳定性没有明显影响,但使快淬态合金的循环稳定性下降,且快淬处理能显著提高合金的循环稳定性.当La替代量从0增加到1.00时,经300次充放循环后,铸态合金的容量保持率(Rh)从59.2%增加到59.8%;16 m/s淬速快淬态合金的容量保持率从83.9%下降到65.0%.对于x=0.45的合金,当淬速从0(铸态被定义为淬速等于0)增加到28 m/s时,容量保持率从59.8%增加到75.8%. 相似文献
68.
5-Fluorouracil (5-FU) is a cornerstone drug used in the treatment of colorectal cancer (CRC). However, the development of resistance to 5-FU and its analogs remain an unsolved problem in CRC treatment. In this study, we investigated the molecular mechanisms and tumor biological aspects of 5-FU resistance in CRC HCT116 cells. We established an acquired 5-FU-resistant cell line, HCT116RF10. HCT116RF10 cells were cross-resistant to the 5-FU analog, fluorodeoxyuridine. In contrast, HCT116RF10 cells were collaterally sensitive to SN-38 and CDDP compared with the parental HCT16 cells. Whole-exome sequencing revealed that a cluster of genes associated with the 5-FU metabolic pathway were not significantly mutated in HCT116 or HCT116RF10 cells. Interestingly, HCT116RF10 cells were regulated by the function of thymidylate synthase (TS), a 5-FU active metabolite 5-fluorodeoxyuridine monophosphate (FdUMP) inhibiting enzyme. Half of the TS was in an active form, whereas the other half was in an inactive form. This finding indicates that 5-FU-resistant cells exhibited increased TS expression, and the TS enzyme is used to trap FdUMP, resulting in resistance to 5-FU and its analogs. 相似文献
69.
将5G无线通信基站安装在电力线杆塔上,可以通过电力线路杆塔共享促进5G网络建设,实现电力企业和通信公司的互利共赢。重点讨论了5G基站的新架构,分析了把基站应用到电力杆塔上应考虑的供电、接地、安装等问题,并给出了相应的解决方案。 相似文献
70.
The calculations of total energy, band structure, and electronic density of states and Mulliken population analysis of β-LaNi5 Hx (5≤x≤8) were performed by adopting the method of total energy based on the density functional theory. The augmented plane wave function was selected as the basis set in combination with ultra-soft pseudo-potential technology. The influence of the amount of H absorbed in alloys was discussed in terms of geometry, electronic structure and thermodynamic derived from calculated results. The results show that the amount of H absorbed and the preferred site occupation of the absorbed hydrogen atoms were controlled by the position of Hbands and the energy gap between H-bands and conduction bands. The β-phase hydrides of LaNi5 are most stable when hydrogen atom capacity coating in the range of 6 - 7. 相似文献