全文获取类型
收费全文 | 10578篇 |
免费 | 453篇 |
国内免费 | 185篇 |
专业分类
电工技术 | 848篇 |
综合类 | 619篇 |
化学工业 | 1910篇 |
金属工艺 | 762篇 |
机械仪表 | 1266篇 |
建筑科学 | 420篇 |
矿业工程 | 263篇 |
能源动力 | 174篇 |
轻工业 | 1218篇 |
水利工程 | 89篇 |
石油天然气 | 109篇 |
武器工业 | 26篇 |
无线电 | 567篇 |
一般工业技术 | 1680篇 |
冶金工业 | 390篇 |
原子能技术 | 134篇 |
自动化技术 | 741篇 |
出版年
2024年 | 14篇 |
2023年 | 58篇 |
2022年 | 189篇 |
2021年 | 196篇 |
2020年 | 125篇 |
2019年 | 129篇 |
2018年 | 174篇 |
2017年 | 206篇 |
2016年 | 323篇 |
2015年 | 535篇 |
2014年 | 631篇 |
2013年 | 557篇 |
2012年 | 706篇 |
2011年 | 988篇 |
2010年 | 960篇 |
2009年 | 819篇 |
2008年 | 725篇 |
2007年 | 752篇 |
2006年 | 655篇 |
2005年 | 460篇 |
2004年 | 373篇 |
2003年 | 322篇 |
2002年 | 323篇 |
2001年 | 209篇 |
2000年 | 162篇 |
1999年 | 115篇 |
1998年 | 85篇 |
1997年 | 57篇 |
1996年 | 54篇 |
1995年 | 47篇 |
1994年 | 35篇 |
1993年 | 50篇 |
1992年 | 25篇 |
1991年 | 28篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 9篇 |
1987年 | 12篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 7篇 |
1974年 | 3篇 |
1973年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Y. Zhang G.R. Lumpkin H. Li M.G. Blackford M. Colella M.L. Carter E.R. Vance 《Journal of Nuclear Materials》2006,350(3):293-300
An amorphous natural brannerite sample was chosen to study the annealing of the radiation damage through thermal recrystallisation, and subsequently to evaluate the effect of radiation damage on its aqueous durability. Microstructural characterisation of the natural brannerite revealed minor alteration along the rim of the crystal and within cracks. The formation of UO2 particles and soluble Pb–Ca-rich aluminosilicate glass is responsible for the higher U and Pb releases from the recrystallised brannerite. In general, natural brannerite has been shown to be resistant to dissolution over geological time, therefore minor brannerite inclusions in ceramic formulations for immobilisation of actinide-rich radioactive wastes should not have a detrimental effect on the long-term chemical durability of the wasteforms. 相似文献
62.
63.
为了提高E^2PROM中N管源漏穿通电压,用实验的方法对制造工艺进行了研究。结果表明,高能量注入是提高VPT的有效手段,但受到pn结击穿的限制,只适用于低区短沟N管;DDD工艺大幅度高VPT,但pn结击穿电压低于20V,不能应用于高压MOS管;采用适量的防穿通注入和适当增大沟道长度为最理想的工艺途径。 相似文献
64.
65.
U.K. Viswanathan R.N. Singh C.B. Basak S. Anantharaman K.C. Sahoo 《Journal of Nuclear Materials》2006,350(3):310-319
Hydride-assisted degradation in fracture toughness of Zircaloy-2 was evaluated by carrying out instrumented drop-weight tests on curved Charpy specimens fabricated from virgin pressure tube. Samples were charged to 60 ppm and 225 ppm hydrogen. Ductile-to-brittle-transition behaviour was exhibited by as-received and hydrided samples. The onset of ductile-to-brittle-transition was at about 130 °C for hydrided samples, irrespective of their hydrogen content. Dynamic fracture toughness (KID) was estimated based on linear elastic fracture mechanics (LEFM) approach. For fractures occurring after general yielding, the fracture toughness was derived based on equivalent energy criterion. Results are supplemented with fractography. This simple procedure of impact testing appears to be promising for monitoring service-induced degradation in fracture toughness of pressure tubes. 相似文献
66.
快速准确地检测出近似重复图像对于版权侵犯检测和检索结果冗余去除具有重要的意义。针对传统方法检测效率低的问题,提出了一种基于E2LSH(Exact Euclidean Locality Sensitive Hashing)的近似重复图像检测新方法。首先,利用E2LSH进行快速过滤,过滤掉大部分非近似重复图像对;然后,对于过滤后剩余的少量图像对,再采用视觉词袋法BoVW(Bag of Visual Words)进一步去除错误的匹配,从而实现近似重复图像检测。实验结果表明,新方法在不明显降低性能的前提下大大加快了近似重复图像检测的速度,在检测性能与速度之间取得了较好的平衡。 相似文献
67.
Contends that Freud discovered transference in connection with material derived from his treatment of Emma Eckstein. The last chapter of Studies on Hysteria by J. Breuer and S. Freud (1895) in which Freud's 1st published use of the term transference occurs, can be read as a working through of the crisis that occurred when Eckstein nearly died. This concept, it is argued, explained Freud's patient's disturbed feelings toward him as a "false connection" and thereby helped to free him of feelings of personal involvement in her libidinal demands. The story of the troubled circumstances under which Freud discovered transference provides insight into the defensive nature of the concept. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
68.
突发钠层(Sporadic Sodium Layer, NaS)是中高层大气金属层最为显著的一种现象,其发生机制目前尚无定论。突发E层(Sporadic E layer, ES)是等离子体密度异常增大的薄层,被认为与NaS密切相关。为进一步研究NaS及ES事件之间相关性及影响因素,利用中国科学院“子午工程”2010~2018年合肥科大站宽带钠荧光共振激光雷达观测结果,并结合武汉左岭镇站数字测高仪及九峰站大气电场仪数据,分析大气电场倒转(即北向电场)对NaS以及ES事件的影响。在统计的91例NaS事件中,发生于大气电场倒转时的比例为20/91; 同时,在发生NaS事件的事例中,ES消失或中断的比例较大(14/20),表明ES可能以提供钠源的形式转化为NaS。此外,在分析武汉左岭镇站数字测高仪数据的同时进行概率统计,结果表明:当大气电场倒转时,ES临界频率减小甚至消失的概率较大(187/242),少数情况下可能造成临界频率增大甚至激发ES生成(55/242); ES虚高消失比例为179/242,ES不变比例为27/242,ES上升比例为23/242。综上所述,大气北向电场在一定程度上对ES事件的发生有抑制作用,并对ES事件的发生高度有明显影响。最后,对一种与电场倒转相关的突发钠层机制也进行了讨论。 相似文献
69.
制造过程实质上是信息采集、传输、处理及应用的过程.将制造信息数字化,用数字信息驱动制造系统完成造物的过程称为数字制造.数字制造不仅能提高制造效率而且能显著降低制造成本.本文以汽车制动系阀盖为例介绍了基于Pro/E的压力铸造模具的开发过程,分析了压力铸造模具数字设计与制造的特点. 相似文献
70.
Clarisse Roblin Steve Chiumento Cdric Jacqueline Eric Pinloche Cendrine Nicoletti Hamza Olleik Elise Courvoisier-Dezord Agns Amouric Christian Basset Louis Dru Marie Ollivier Aurlie Bogey-Lambert Nicolas Vidal Mohamed Atta Marc Maresca Estelle Devillard Victor Duarte Josette Perrier Mickael Lafond 《International journal of molecular sciences》2021,22(6)
The world is on the verge of a major antibiotic crisis as the emergence of resistant bacteria is increasing, and very few novel molecules have been discovered since the 1960s. In this context, scientists have been exploring alternatives to conventional antibiotics, such as ribosomally synthesized and post-translationally modified peptides (RiPPs). Interestingly, the highly potent in vitro antibacterial activity and safety of ruminococcin C1, a recently discovered RiPP belonging to the sactipeptide subclass, has been demonstrated. The present results show that ruminococcin C1 is efficient at curing infection and at protecting challenged mice from Clostridium perfringens with a lower dose than the conventional antibiotic vancomycin. Moreover, antimicrobial peptide (AMP) is also effective against this pathogen in the complex microbial community of the gut environment, with a selective impact on a few bacterial genera, while maintaining a global homeostasis of the microbiome. In addition, ruminococcin C1 exhibits other biological activities that could be beneficial for human health, as well as other fields of applications. Overall, this study, by using an in vivo infection approach, confirms the antimicrobial clinical potential and highlights the multiple functional properties of ruminococcin C1, thus extending its therapeutic interest. 相似文献