全文获取类型
收费全文 | 1712篇 |
免费 | 115篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 9篇 |
综合类 | 1篇 |
化学工业 | 742篇 |
金属工艺 | 15篇 |
机械仪表 | 22篇 |
建筑科学 | 60篇 |
矿业工程 | 1篇 |
能源动力 | 41篇 |
轻工业 | 342篇 |
水利工程 | 13篇 |
石油天然气 | 5篇 |
无线电 | 86篇 |
一般工业技术 | 249篇 |
冶金工业 | 46篇 |
原子能技术 | 6篇 |
自动化技术 | 190篇 |
出版年
2024年 | 2篇 |
2023年 | 28篇 |
2022年 | 225篇 |
2021年 | 215篇 |
2020年 | 82篇 |
2019年 | 61篇 |
2018年 | 69篇 |
2017年 | 53篇 |
2016年 | 75篇 |
2015年 | 65篇 |
2014年 | 84篇 |
2013年 | 109篇 |
2012年 | 98篇 |
2011年 | 120篇 |
2010年 | 92篇 |
2009年 | 72篇 |
2008年 | 71篇 |
2007年 | 64篇 |
2006年 | 46篇 |
2005年 | 43篇 |
2004年 | 32篇 |
2003年 | 20篇 |
2002年 | 24篇 |
2001年 | 12篇 |
2000年 | 9篇 |
1999年 | 8篇 |
1998年 | 13篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1990年 | 1篇 |
1989年 | 6篇 |
1988年 | 1篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有1828条查询结果,搜索用时 0 毫秒
121.
In many cases masonry buildings present structural problems related to development of local mechanisms under seismic actions. The solution to this weakness has to be chosen taking into account several aspects if the construction is ancient and is gifted of monumental significance. In this paper the case of the Bell Tower of Santa Maria del Carmine (Napoli, Italy) is discussed; the construction has been deeply examined by the writers performing experimental inquires in situ and theoretical analysis with three-dimensional models. While the results obtained in the hypothesis of compact behavior of the structure have pointed out a low risk condition under seismic actions, in contrast the study of local out-of-plane mechanisms, dealt with in detail in this paper, have evidenced an unsafe situation. To avoid such mechanisms, connective systems with tie rods made of glass fiber-reinforced polymer laminates have been designed to be inserted where local verifications are not satisfied. Design, application, and monitoring procedures of this innovative intervention are discussed in detail herein. 相似文献
122.
123.
Thirty commercially available Italian carbonic macerated young red wines, have been analysed by HPLC–DAD–MS with the aim to characterise their pigment composition and find possible correlations with the colour features evaluated by means of spectrophotometric measurements. The composition in anthocyanin monoglucosides, acetates, p-coumarates as well as that in pyranoanthocyanins and direct and ethyl-bridged adducts with flavanols, was studied. Because of the peculiar maceration process, carbonic macerated wines demonstrated to be qualitatively rich in pyranoanthocyanins and pigment adducts. A number of ethyl-bridged anthocyanin isomers was found, together with significant contents of vitisin A and vitisin B (up to 15.5 mg/L as a sum). Malvidin-3-glc-4-vinylphenol was the main pyranoanthocyanin-vinylphenol adduct (up to 1.10 mg/L). The colour features of the wines were broadly distributed as a consequence of the percentage of carbonic macerated wine present in the marketed product. The statistical treatment of the entire data set revealed that pyranoanthocyanins are positively correlated with colour density (while no correlation was found for monoglucosides) and that direct adducts and/or ethyl-bridged compounds can play a role for what concerns the hue of carbonic macerated wines. 相似文献
124.
Nanocapsules: Ultrastable Liquid–Liquid Interface as Viable Route for Controlled Deposition of Biodegradable Polymer Nanocapsules (Small 22/2016) 下载免费PDF全文
125.
Batistella Marcos Kadri Ouassila Regazzi Arnaud Pucci Monica Francesca Lopez-Cuesta José-Marie Ayme Florence Bordeaux David 《Journal of Materials Science》2022,57(1):739-754
Journal of Materials Science - In this study coatings of kaolin and talc particles were successfully applied on the surface of polyamide 12 powder intended for laser sintering (LS). Microscopic... 相似文献
126.
127.
Social wasps encompass species displaying diverse social organization regarding colony cycle, nest foundation, caste differences (from none to significant dimorphism) and number of reproductive queens. Current phylogenetic data suggests that sociality occured independently in the subfamily Stenogastrinae and in the Polistinae+Vespinae clade. In most species, including those with the simplest social organization, colony reproduction is monopolised by a single or few females. Since their nest mates can also develop ovaries and lay eggs, dominant females must somehow inhibit them from reproducing. Physical interactions in the form of open aggression or, usually, ritualised dominance by the fertile females contribute to fertility inhibition in several species, but it is unlikely to function in large colonies. In the latter case, reproduction within the colony is likely to be regulated through pheromones. Relatively little is known about these semiochemicals. Studies on all the three social wasp subfamilies, revealed that cuticular hydrocarbon components differ in abundance between egg-laying and not egg-laying females and that their composition depends on fertility status. In several species, females have been reported to manifestly react towards females with activated ovaries, but there is little evidence to support the hypothesis that fertile individuals are either recognized through their CHC composition, or that over-represented CHC constituents can inhibit fertility. Moreover, very little information exists on the possibility that exocrine glands release fertility signals or chemicals inhibiting fertility. 相似文献
128.
129.
Silvia Francesca Storti Emanuela Formaggio Deborah Moretto Alessandra Bertoldo Francesca Benedetta Pizzini Alberto Beltramello Antonio Fiaschi Gianna Maria Toffolo Paolo Manganotti 《Magma (New York, N.Y.)》2014,27(2):171-184
Objective
Among other neuroimaging techniques, functional magnetic resonance imaging (fMRI) can be useful for studying the development of motor fatigue. The aim of this study was to identify differences in cortical neuronal activation in nine subjects on three motor tasks: right-hand movement with minimum, maximum, and post-fatigue maximum finger flexion.Materials and methods
fMRI activation maps for each subject and during each condition were obtained by estimating the optimal model of the hemodynamic response function (HRF) out of four standard HRF models and an individual-based HRF model (ibHRF).Results
ibHRF was selected as the optimal model in six out of nine subjects for minimum movement, in five out of nine for maximum movement, and in eight out of nine for post-fatigue maximum movement. As compared to maximum movement, a large reduction in the total number of active voxels (primary sensorimotor area, supplementary motor area and cerebellum) was observed in post-fatigue maximum movement.Conclusion
This is the first approach to the evaluation of long-lasting contraction effort in healthy subjects by means of the fMRI paradigm with the use of an individual-based hemodynamic response. The results may be relevant for defining a baseline in future studies on central fatigue in patients with neuropathological disorders. 相似文献130.
Charles E. CarraherJr. Michael R. Roner Anthony G. Campbell Alisa Moric-Johnson Lindsey Miller Paul Slawek Francesca Mosca Jeffrey D. Einkauf Jerome E. Haky Ryan Crichton 《Journal of Inorganic and Organometallic Polymers and Materials》2018,28(2):481-491
Organotin polyesters were synthesized from d-camphoric acid. Since d-camphoric acid is a natural product, this is part of the green chemistry initiative. Further, synthesis occurred employing commercially available reactants and the interfacial system which is used industrially to synthesize aramids and polycarbonates. Thus, scale-up is straightforward. Polymers were synthesized employing the interfacial reaction between various organotin dihalides and the salt of d-camphoric acid. Reaction was rapid occurring in 30 s and less. Product yield was good except for the product from dioctyltin dichloride. The products are polymeric with chain lengths from 230 to 2200. Structural characterization with infrared spectrometry and MALDI MS are consistent with the formation of organotin polyesters containing the camphoric acid moiety within its backbone. IR shows formation of the Sn–OOC(O) linkage with the polymer having a combination of bridging and non-bridging geometrical arrangements about the tin atom. MALDI MS shows ion fragment to two and three repeat units. The products exhibit good ability to inhibit a battery of cancer cells including those from pancreatic cancer. The effective concentration for inhibition of the cancer cell lines are generally in the same range as those found for cisplatin and in the ng/mL range. 相似文献