全文获取类型
收费全文 | 4045篇 |
免费 | 298篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 59篇 |
综合类 | 3篇 |
化学工业 | 1068篇 |
金属工艺 | 77篇 |
机械仪表 | 143篇 |
建筑科学 | 144篇 |
矿业工程 | 7篇 |
能源动力 | 120篇 |
轻工业 | 640篇 |
水利工程 | 36篇 |
石油天然气 | 21篇 |
无线电 | 328篇 |
一般工业技术 | 722篇 |
冶金工业 | 397篇 |
原子能技术 | 21篇 |
自动化技术 | 562篇 |
出版年
2024年 | 7篇 |
2023年 | 38篇 |
2022年 | 115篇 |
2021年 | 214篇 |
2020年 | 111篇 |
2019年 | 137篇 |
2018年 | 154篇 |
2017年 | 166篇 |
2016年 | 182篇 |
2015年 | 129篇 |
2014年 | 170篇 |
2013年 | 294篇 |
2012年 | 253篇 |
2011年 | 278篇 |
2010年 | 247篇 |
2009年 | 229篇 |
2008年 | 204篇 |
2007年 | 166篇 |
2006年 | 141篇 |
2005年 | 121篇 |
2004年 | 89篇 |
2003年 | 109篇 |
2002年 | 109篇 |
2001年 | 62篇 |
2000年 | 46篇 |
1999年 | 69篇 |
1998年 | 107篇 |
1997年 | 70篇 |
1996年 | 65篇 |
1995年 | 45篇 |
1994年 | 37篇 |
1993年 | 23篇 |
1992年 | 12篇 |
1991年 | 14篇 |
1990年 | 11篇 |
1989年 | 19篇 |
1988年 | 10篇 |
1987年 | 5篇 |
1986年 | 9篇 |
1985年 | 10篇 |
1984年 | 11篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1978年 | 8篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1964年 | 2篇 |
排序方式: 共有4348条查询结果,搜索用时 31 毫秒
1.
2.
Pedro Ideia Lorenzo Degli Esposti Carla Caseiro Miguel Alessio Adamiano Michele Iafisco Paula C. Castilho 《International Journal of Applied Ceramic Technology》2021,18(1):235-243
The conversion of food industry by-products to compounds with high added value is nowadays a significant topic, for social, environmental, and economic reasons. In this paper, calcium phosphate-based materials were obtained from black scabbardfish (Aphanopus carbo) bones and grey triggerfish (Balistes capriscus) skin, which are two of the most abundant fish by-products of Madeira Island. Different calcination temperatures between 400 and 1000°C were employed. Materials obtained from calcination of bones of black scabbard fish were composed by homogeneous mixtures of hydroxyapatite (Ca10(PO4)6(OH)2, HAp) and β-tricalcium phosphate (β-Ca3(PO4)2, β-TCP). Because of the high biocompatibility of HAp and the good resorbability of β-TCP, these natural biphasic materials could be very relevant in the field of biomaterials, as bone grafts. The ratio between HAp and β-TCP in the biphasic compound was dependent on the calcination temperature. Differently, the material obtained from skin of grey triggerfish contained HAp as the main phase, together with small amounts of other mineral phases, such as halite and rhenanite, which are known to enhance osteogenesis when used as bone substitutes. In both cases, the increase of calcination temperature led to an increase in the particles size with a consequent decrease in their specific surface area. These results demonstrate that from the fish by-products of the most consumed fishes in Madeira Island it is possible to obtain bioceramic materials with tunable composition and particle morphology, which could be promising materials for the biomedical field. 相似文献
3.
Marco Bocchetti Maria Grazia Ferraro Filippo Ricciardiello Alessandro Ottaiano Amalia Luce Alessia Maria Cossu Marianna Scrima Wing-Yan Leung Marianna Abate Paola Stiuso Michele Caraglia Silvia Zappavigna Tung On Yau 《International journal of molecular sciences》2021,22(8)
Colorectal cancer (CRC) is the third most deadly cancer worldwide, and inflammatory bowel disease (IBD) is one of the critical factors in CRC carcinogenesis. IBD is responsible for an unphysiological and sustained chronic inflammation environment favoring the transformation. MicroRNAs (miRNAs) belong to a class of highly conserved short single-stranded segments (18–25 nucleotides) non-coding RNA and have been extensively discussed in both CRC and IBD. However, the role of miRNAs in the development of colitis-associated CRC (CAC) is less clear. The aim of this review is to summarize the major upregulated (miR-18a, miR-19a, miR-21, miR-31, miR-155 and miR-214) and downregulated (miR-124, miR-193a-3p and miR-139-5p) miRNAs in CAC, and their roles in genes’ expression modulation in chronic colonic-inflammation-induced carcinogenesis, including programmed cell-death pathways. These miRNAs dysregulation could be applied for early CAC diagnosis, to predict therapy efficacy and for precision treatment. 相似文献
4.
Laís D. Silva Fernanda C. Puosso Viviane O. Soares Oscar Peitl Filho Simone do R.F. Sabino Francisco C. Serbena Murilo C. Crovace Edgar D. Zanotto 《Ceramics International》2021,47(13):18720-18731
Bioactive glasses and glass-ceramics (GCs) effectively regenerate bone tissue, however most GCs show improved mechanical properties. In this work, we developed and tested a rarely studied bioactive glass composition (24.4K2O-26.9CaO-46.1SiO2-2.6P2O5 mol%, identified as 45S5-K) with different particle sizes and heating rates to obtain a sintered GC that combines good fracture strength, low elastic modulus, and bioactivity. We analyzed the influence of the sintering processing conditions in the elastic modulus, Vickers microhardness, density, and crystal phase formation in the GC. The best GC shows improved properties compared with its parent glass. This glass achieves a good densification degree with a two-step viscous flow sintering approach and the resulting GC shows as high bioactivity as that of the standard 45S5 Bioglass®. Furthermore, the GC elastic modulus (56 GPa) is relatively low, minimizing stress shielding. Therefore, we unveiled the glass sintering behavior with concurrent crystallization of this complex bioactive glass composition and developed a potential GC for bone regeneration. 相似文献
5.
Fabiana Piscitelli Roberto Coccurello Antonio Totaro Alessandro Leuti Giacomo Giacovazzo Roberta Verde Emanuela Rossi Michele Podaliri Vulpiani Nicola Ferri Roberto Giacominelli Stuffler Vincenzo Di Marzo Sergio Oddi Tiziana Bisogno Mauro Maccarrone 《European Journal of Lipid Science and Technology》2019,121(10)
6.
7.
Traditionally, in supervised machine learning, (a significant) part of the available data (usually 50%-80%) is used for training and the rest—for validation. In many problems, however, the data are highly imbalanced in regard to different classes or does not have good coverage of the feasible data space which, in turn, creates problems in validation and usage phase. In this paper, we propose a technique for synthesizing feasible and likely data to help balance the classes as well as to boost the performance in terms of confusion matrix as well as overall. The idea, in a nutshell, is to synthesize data samples in close vicinity to the actual data samples specifically for the less represented (minority) classes. This has also implications to the so-called fairness of machine learning. In this paper, we propose a specific method for synthesizing data in a way to balance the classes and boost the performance, especially of the minority classes. It is generic and can be applied to different base algorithms, for example, support vector machines, k-nearest neighbour classifiers deep neural, rule-based classifiers, decision trees, and so forth. The results demonstrated that (a) a significantly more balanced (and fair) classification results can be achieved and (b) that the overall performance as well as the performance per class measured by confusion matrix can be boosted. In addition, this approach can be very valuable for the cases when the number of actual available labelled data is small which itself is one of the problems of the contemporary machine learning. 相似文献
8.
9.
正项目地址_中国北京项目面积_8000m~2设计单位_ArkA北京亦庄半岛幼儿园项目是设计团队与半岛教育集团的第二次合作,目标是将蒙特梭利教育理念和建筑设计融为一体,创造出一个更合理的空间和安全的环境,让孩子们能够自由快乐地学习和成长。原有的建筑物是一个开放的空间,整个大空间分作4层。设计团队的首要任务是根据孩子的比例改造空间。在设计时,设计团队加入了许多小房屋的设计,以此让孩子更具有主人感和安全感。对教室的设计是简约的房屋;图书馆则是一个开放空间,在其中央种下一棵树,好似一个乡村小镇的广场;走廊设计成多功能的开放空间,孩子 相似文献