全文获取类型
收费全文 | 4408篇 |
免费 | 305篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 92篇 |
综合类 | 19篇 |
化学工业 | 993篇 |
金属工艺 | 90篇 |
机械仪表 | 75篇 |
建筑科学 | 344篇 |
矿业工程 | 19篇 |
能源动力 | 129篇 |
轻工业 | 302篇 |
水利工程 | 31篇 |
石油天然气 | 2篇 |
无线电 | 398篇 |
一般工业技术 | 908篇 |
冶金工业 | 487篇 |
原子能技术 | 22篇 |
自动化技术 | 808篇 |
出版年
2024年 | 6篇 |
2023年 | 58篇 |
2022年 | 79篇 |
2021年 | 158篇 |
2020年 | 121篇 |
2019年 | 101篇 |
2018年 | 135篇 |
2017年 | 122篇 |
2016年 | 165篇 |
2015年 | 170篇 |
2014年 | 197篇 |
2013年 | 287篇 |
2012年 | 278篇 |
2011年 | 338篇 |
2010年 | 284篇 |
2009年 | 227篇 |
2008年 | 241篇 |
2007年 | 245篇 |
2006年 | 176篇 |
2005年 | 167篇 |
2004年 | 125篇 |
2003年 | 96篇 |
2002年 | 98篇 |
2001年 | 66篇 |
2000年 | 60篇 |
1999年 | 64篇 |
1998年 | 133篇 |
1997年 | 81篇 |
1996年 | 85篇 |
1995年 | 54篇 |
1994年 | 44篇 |
1993年 | 43篇 |
1992年 | 19篇 |
1991年 | 19篇 |
1990年 | 22篇 |
1989年 | 26篇 |
1988年 | 11篇 |
1986年 | 9篇 |
1985年 | 14篇 |
1984年 | 7篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 10篇 |
1977年 | 7篇 |
1976年 | 12篇 |
1975年 | 6篇 |
1973年 | 7篇 |
1971年 | 4篇 |
1970年 | 4篇 |
排序方式: 共有4719条查询结果,搜索用时 15 毫秒
1.
Matteo Di Giosia Alice Soldà Markus Seeger Andrea Cantelli Fabio Arnesano Maria I. Nardella Vincenzo Mangini Francesco Valle Marco Montalti Francesco Zerbetto Stefania Rapino Matteo Calvaresi Vasilis Ntziachristos 《Advanced functional materials》2021,31(20):2101527
Fullerenes are candidates for theranostic applications because of their high photodynamic activity and intrinsic multimodal imaging contrast. However, fullerenes suffer from low solubility in aqueous media, poor biocompatibility, cell toxicity, and a tendency to aggregate. C70@lysozyme is introduced herein as a novel bioconjugate that is harmless to a cellular environment, yet is also photoactive and has excellent optical and optoacoustic contrast for tracking cellular uptake and intracellular localization. The formation, water-solubility, photoactivity, and unperturbed structure of C70@lysozyme are confirmed using UV-visible and 2D 1H, 15N NMR spectroscopy. The excellent imaging contrast of C70@lysozyme in optoacoustic and third harmonic generation microscopy is exploited to monitor its uptake in HeLa cells and lysosomal trafficking. Last, the photoactivity of C70@lysozyme and its ability to initiate cell death by means of singlet oxygen (1O2) production upon exposure to low levels of white light irradiation is demonstrated. This study introduces C70@lysozyme and other fullerene-protein conjugates as potential candidates for theranostic applications. 相似文献
2.
3.
4.
This paper presents an integrated passive damping approach in hybrid metal-CFRP parts for structural applications. In this concept a viscoelastic material is embedded in the joint zone of the hybrid component. To examine the connection strength single-lap-joint specimens were produced and tested and the influence of the used material combinations, different surface structures, and different process parameters i.e. the moment of cross-linking were evaluated. Afterwards, the metal-CFRP hybrids were tested in quasi-static tests to assess their connection strength and failure behaviour. Dynamic cyclic tensile tests with step-wise increased loading conditions were performed to determine the specimens damping behaviour and to estimate their fatigue performance. Finally, these results are compared to a state of the art metal-CFRP hybrid with rivets connecting both materials. 相似文献
5.
6.
Pavel Strunz Debashis Mukherji Přemysl Beran Ralph Gilles Lukas Karge Michael Hofmann Markus Hoelzel Joachim Rösler Gergely Farkas 《Metals and Materials International》2018,24(5):934-944
An addition of boron largely increases the ductility in polycrystalline high-temperature Co–Re alloys. Therefore, the effect of boron on the alloy structural characteristics is of high importance for the stability of the matrix at operational temperatures. Volume fractions of ε (hexagonal close-packed—hcp), γ (face-centered cubic—fcc) and σ (Cr2Re3 type) phases were measured at ambient and high temperatures (up to 1500 °C) for a boron-containing Co–17Re–23Cr alloy using neutron diffraction. The matrix phase undergoes an allotropic transformation from ε to γ structure at high temperatures, similar to pure cobalt and to the previously investigated, more complex Co–17Re–23Cr–1.2Ta–2.6C alloy. It was determined in this study that the transformation temperature depends on the boron content (0–1000 wt. ppm). Nevertheless, the transformation temperature did not change monotonically with the increase in the boron content but reached a minimum at approximately 200 ppm of boron. A probable reason is the interplay between the amount of boron in the matrix and the amount of σ phase, which binds hcp-stabilizing elements (Cr and Re). Moreover, borides were identified in alloys with high boron content. 相似文献
7.
Defects are often present in rolled products, such as wire rod. The market demand for wire rod without any defects has increased. In the final wire rod products, defects originating from steel making, casting, pre‐rolling of billets and during wire rod rolling can appear. In this work, artificial V‐shaped longitudinal surface cracks have been analysed experimentally and by means of FEM. The results indicate that the experiments and FEM calculations show the same tendency except in two cases, where instability due to fairly “round” false round bars disturbed the experiment. FE studies in combination with practical experiments are necessary in order to understand the behaviour of the material flows in the groove and to explain whether the crack will open up as a V‐shape or if it will be closed as an I‐shape. 相似文献
8.
9.
H Eriksson 《Canadian Metallurgical Quarterly》1996,2(3):163-168
This paper reviews recent changes in morbidity and mortality of respiratory syncytial virus (RSV) infection in infants with congenital heart disease. Mortality since the late 1970s has declined substantially, from approximately 37% to 3%. Although the frequency of admission to intensive care units has declined from approximately 60% to 30%, the frequency for mechanical ventilatory support has not changed significantly. Because mortality dropped prior to the widespread use of ribavirin, it is difficult to ascribe the improvement to this therapy. In infants with congenital heart disease (CHD), nosocomial infection remains a significant problem, accounting for approximately 33% of the RSV cases. Some authors report significant reductions in hospital-acquired RSV by use of gloves and gowns for contacts with infectious cases. Efforts at primary prevention have encountered problems with development of an RSV vaccine. Preliminary data from studies of passive immunization using immune globulins with high RSV antibody titers suggest that this therapy may reduce the severity of RSV infection in infants with serious heart disease. 相似文献
10.