全文获取类型
收费全文 | 23804篇 |
免费 | 1774篇 |
国内免费 | 848篇 |
专业分类
电工技术 | 2230篇 |
综合类 | 2691篇 |
化学工业 | 707篇 |
金属工艺 | 1136篇 |
机械仪表 | 4862篇 |
建筑科学 | 6173篇 |
矿业工程 | 1511篇 |
能源动力 | 667篇 |
轻工业 | 419篇 |
水利工程 | 1190篇 |
石油天然气 | 931篇 |
武器工业 | 158篇 |
无线电 | 370篇 |
一般工业技术 | 1092篇 |
冶金工业 | 1308篇 |
原子能技术 | 142篇 |
自动化技术 | 839篇 |
出版年
2024年 | 66篇 |
2023年 | 239篇 |
2022年 | 589篇 |
2021年 | 687篇 |
2020年 | 757篇 |
2019年 | 489篇 |
2018年 | 464篇 |
2017年 | 574篇 |
2016年 | 711篇 |
2015年 | 823篇 |
2014年 | 1579篇 |
2013年 | 1069篇 |
2012年 | 1814篇 |
2011年 | 1868篇 |
2010年 | 1387篇 |
2009年 | 1455篇 |
2008年 | 1215篇 |
2007年 | 1747篇 |
2006年 | 1575篇 |
2005年 | 1332篇 |
2004年 | 1019篇 |
2003年 | 904篇 |
2002年 | 861篇 |
2001年 | 670篇 |
2000年 | 567篇 |
1999年 | 430篇 |
1998年 | 366篇 |
1997年 | 267篇 |
1996年 | 245篇 |
1995年 | 163篇 |
1994年 | 151篇 |
1993年 | 90篇 |
1992年 | 58篇 |
1991年 | 36篇 |
1990年 | 38篇 |
1989年 | 31篇 |
1988年 | 17篇 |
1987年 | 18篇 |
1986年 | 11篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 13篇 |
1980年 | 10篇 |
1979年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
In actual engineering scenarios, limited fault data leads to insufficient model training and over-fitting, which negatively affects the diagnostic performance of intelligent diagnostic models. To solve the problem, this paper proposes a variational information constrained generative adversarial network (VICGAN) for effective machine fault diagnosis. Firstly, by incorporating the encoder into the discriminator to map the deep features, an improved generative adversarial network with stronger data synthesis capability is established. Secondly, to promote the stable training of the model and guarantee better convergence, a variational information constraint technique is utilized, which constrains the input signals and deep features of the discriminator using the information bottleneck method. In addition, a representation matching module is added to impose restrictions on the generator, avoiding the mode collapse problem and boosting the sample diversity. Two rolling bearing datasets are utilized to verify the effectiveness and stability of the presented network, which demonstrates that the presented network has an admirable ability in processing fault diagnosis with few samples, and performs better than state-of-the-art approaches. 相似文献
2.
This paper introduces the potential feasibility that ELID (electrolytic in-process dressing) grinding replaces superfinishing in bearing manufacturing, but ELID grinding will bring new challenges. Different regions present distinguish surface profile due to the non-uniform contact in ELID groove grinding. However, few reports explaining the non-uniform contact are available. This article explores the mechanisms of the non-uniform contact during ELID groove grinding. Experiments on the non-uniform contact between bearing raceway and grinding wheel have been carried out under different conditions. The results show that non-uniform contact exists in ELID groove grinding process and it exerts influence on the profile of the raceway surface. Non-uniform contact influences the Rsk and Rku value all the time, but it influences the Ra value occasionally. Improvement strategies of eliminating the non-uniform contact are also discussed based on the experimental study. 相似文献
3.
Mri Miczi Mria Golda Balzs Kunkli Tibor Nagy Jzsef Tzsr Jnos Andrs Mtyn 《International journal of molecular sciences》2020,21(24)
The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease-19 (COVID-19) being associated with severe pneumonia. Like with other viruses, the interaction of SARS-CoV-2 with host cell proteins is necessary for successful replication, and cleavage of cellular targets by the viral protease also may contribute to the pathogenesis, but knowledge about the human proteins that are processed by the main protease (3CLpro) of SARS-CoV-2 is still limited. We tested the prediction potentials of two different in silico methods for the identification of SARS-CoV-2 3CLpro cleavage sites in human proteins. Short stretches of homologous host-pathogen protein sequences (SSHHPS) that are present in SARS-CoV-2 polyprotein and human proteins were identified using BLAST analysis, and the NetCorona 1.0 webserver was used to successfully predict cleavage sites, although this method was primarily developed for SARS-CoV. Human C-terminal-binding protein 1 (CTBP1) was found to be cleaved in vitro by SARS-CoV-2 3CLpro, the existence of the cleavage site was proved experimentally by using a His6-MBP-mEYFP recombinant substrate containing the predicted target sequence. Our results highlight both potentials and limitations of the tested algorithms. The identification of candidate host substrates of 3CLpro may help better develop an understanding of the molecular mechanisms behind the replication and pathogenesis of SARS-CoV-2. 相似文献
4.
5.
采用3阶精度的迎风格式及2阶精度的中心差分格式,直接求解二维非定常N-S方程组,研究狭缝节流空气静压轴承压降恢复之后区域的流场特性。使用雷诺方程计算相同位置气膜中心处的流场状态,并与直接数值模拟方法的计算结果进行对比。结果表明:雷诺方程与N-S方程在计算域内计算结果基本一致,两者压力偏差为0.173%,速度偏差为1.217%;流场压力、密度沿气流方向逐渐减小,但在气膜方向几乎不变;流场速度、压力梯度沿气流方向逐渐增加,速度在流场出口处达到最大值;直接数值模拟方法得到了流场的温度变化,即整个流场的温度变化很小,温度整体呈上下高、中心低的分布,而雷诺方程无法计算得出整个流场的温度变化情况;采用雷诺方程计算轴承压降恢复之后区域的流场是合理的。 相似文献
6.
7.
8.
9.
东海盆地油气勘探焦点问题探讨 总被引:3,自引:0,他引:3
东海盆地自西向东可分为 3个带 ,即西部断陷带、中部隆起带和东部断坳带 ,其构造格局各具特色 ,并且均有自身的烃源岩。西部断陷带由多个以古新世为发育高峰期的半地堑组成 ,主要烃源岩为下古新统湖相泥岩 ,该带有利的勘探区是丽水、椒江凹陷 ,围绕下古新统主力烃源岩寻找油气是丽水、椒江凹陷油气勘探的焦点 ;中部隆起带是中生界残留盆地的叠置区 ,主要烃源岩为侏罗系湖相泥岩 ,福州凹陷是该带较有利的勘探区 ,烃源岩的规模、潜力以及圈闭保存条件是福州凹陷油气勘探的焦点 ;东部断坳带是厚度逾万米的新生代沉积断坳区 ,主要烃源岩为始新世煤系地层 ,该带有利的勘探区是西湖凹陷 ,烃源岩和盖层条件是西湖凹陷油气勘探的关键。目前 ,东海盆地比较现实和最具勘探前景的地区是西湖凹陷及丽水、椒江凹陷 相似文献
10.
分析了MOSFET误导通产生的原因,分别从原理和理论推导两个方面作了分析,主要考虑了开关管中寄生参数对开关特性的影响。通过求解误导通发生的条件,得到哪些参数会导致误触发,最后给出了仿真。文中还提出如何避免MOSFET误导通产生,以及改进方法,对减少实际应用中MOSFET破坏性损坏有一定意义。 相似文献