全文获取类型
收费全文 | 4253篇 |
免费 | 297篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 85篇 |
综合类 | 19篇 |
化学工业 | 982篇 |
金属工艺 | 92篇 |
机械仪表 | 70篇 |
建筑科学 | 342篇 |
矿业工程 | 18篇 |
能源动力 | 116篇 |
轻工业 | 333篇 |
水利工程 | 39篇 |
石油天然气 | 2篇 |
无线电 | 384篇 |
一般工业技术 | 883篇 |
冶金工业 | 376篇 |
原子能技术 | 17篇 |
自动化技术 | 796篇 |
出版年
2024年 | 6篇 |
2023年 | 64篇 |
2022年 | 85篇 |
2021年 | 155篇 |
2020年 | 123篇 |
2019年 | 103篇 |
2018年 | 127篇 |
2017年 | 110篇 |
2016年 | 166篇 |
2015年 | 178篇 |
2014年 | 192篇 |
2013年 | 279篇 |
2012年 | 263篇 |
2011年 | 336篇 |
2010年 | 273篇 |
2009年 | 227篇 |
2008年 | 233篇 |
2007年 | 228篇 |
2006年 | 177篇 |
2005年 | 165篇 |
2004年 | 116篇 |
2003年 | 97篇 |
2002年 | 87篇 |
2001年 | 61篇 |
2000年 | 56篇 |
1999年 | 65篇 |
1998年 | 78篇 |
1997年 | 68篇 |
1996年 | 65篇 |
1995年 | 46篇 |
1994年 | 31篇 |
1993年 | 30篇 |
1992年 | 16篇 |
1991年 | 16篇 |
1990年 | 15篇 |
1989年 | 26篇 |
1988年 | 12篇 |
1986年 | 12篇 |
1985年 | 9篇 |
1984年 | 6篇 |
1981年 | 6篇 |
1979年 | 13篇 |
1977年 | 9篇 |
1976年 | 19篇 |
1975年 | 6篇 |
1973年 | 10篇 |
1971年 | 5篇 |
1969年 | 6篇 |
1940年 | 8篇 |
1938年 | 5篇 |
排序方式: 共有4554条查询结果,搜索用时 31 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.
Vector coupled-mode theory of dielectric waveguides 总被引:1,自引:0,他引:1
A consistent derivation of a system of vector coupled-mode (VCM) equations for parallel dielectric waveguides is presented and compared with earlier versions of the improved coupled-mode theory (ICMT). As a validity test, it is shown that the effectively scalar transverse electric and transverse magnetic (TM) coupled-mode (CM) equations are direct limits of our full VCM formulation. In particular, our formulation does not lead to the fundamental error found with earlier coupled-mode theories (CMTs) in a case of TM fields. Functional equations of our VCMT are consistent with Maxwell's equations and lead to higher precision. They can be applied to complicated arrays of strongly coupled parallel dielectric waveguides with true vectorial behavior. 相似文献
8.
9.
H Neudeck M Joncic C Schuster S Bisson R Hildebrandt T Oney B Stiemer H Hopp R Graf 《Canadian Metallurgical Quarterly》1997,37(6):449-458
Nitric oxide (NO) acts as a modulator of neuronal transmission in mature neuronal systems, including the retina. Recently, NO has also been suggested to have a trophic function during development. We examined immunocytochemically the distribution of NO-producing cells in developing and transplanted rabbit retinas. An antibody detecting the neuronal isoform of its biosynthetic enzyme, nitric oxide synthase (NOS), was used on normal developing retinas [starting at embryonic day (E) 15] and on rabbit retinal transplants after various survival times (1-139 days after surgery). Weakly stained cell bodies were first observed in the proximal margin of the neuroblastic layer at E 29. Stained processes projecting towards a developing inner plexiform layer were also visible at this time point. Immunoreactive cells were located at later stages in the innermost part of the inner nuclear layer and in the ganglion cell layer, and are likely to correspond mainly to amacrine cells. NOS-labelled cells were also found in retinal transplants. The first NOS-labelled cells appeared, as in normal developing retinas, in ages corresponding to E 29 and were still detected in transplants corresponding to postnatal day 123. NOS-labelled cells were seen in areas between rosettes, where amacrine cells are located. NOS-labelled processes were at times seen to project for long distances, forming very distinct plexuses. NOS-containing amacrine cells thus appear both in the transplants and in developing retinas in the embryonic stages, long before synaptic function involving these cells can be expected, suggesting a role for NO not only in neuromodulation but also in retinal development. 相似文献
10.