全文获取类型
收费全文 | 2261篇 |
免费 | 170篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 12篇 |
综合类 | 1篇 |
化学工业 | 857篇 |
金属工艺 | 39篇 |
机械仪表 | 43篇 |
建筑科学 | 117篇 |
矿业工程 | 4篇 |
能源动力 | 61篇 |
轻工业 | 455篇 |
水利工程 | 15篇 |
石油天然气 | 9篇 |
无线电 | 81篇 |
一般工业技术 | 314篇 |
冶金工业 | 168篇 |
原子能技术 | 12篇 |
自动化技术 | 245篇 |
出版年
2024年 | 11篇 |
2023年 | 37篇 |
2022年 | 136篇 |
2021年 | 167篇 |
2020年 | 68篇 |
2019年 | 68篇 |
2018年 | 60篇 |
2017年 | 72篇 |
2016年 | 92篇 |
2015年 | 80篇 |
2014年 | 80篇 |
2013年 | 179篇 |
2012年 | 122篇 |
2011年 | 162篇 |
2010年 | 129篇 |
2009年 | 132篇 |
2008年 | 115篇 |
2007年 | 81篇 |
2006年 | 57篇 |
2005年 | 50篇 |
2004年 | 46篇 |
2003年 | 39篇 |
2002年 | 34篇 |
2001年 | 36篇 |
2000年 | 28篇 |
1999年 | 28篇 |
1998年 | 35篇 |
1997年 | 26篇 |
1996年 | 26篇 |
1995年 | 19篇 |
1994年 | 18篇 |
1993年 | 20篇 |
1992年 | 16篇 |
1991年 | 11篇 |
1990年 | 16篇 |
1989年 | 11篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 12篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 12篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1977年 | 7篇 |
1976年 | 11篇 |
1975年 | 5篇 |
1963年 | 2篇 |
排序方式: 共有2433条查询结果,搜索用时 635 毫秒
1.
Michael Lommel Vera Froese Moritz Sieber Marvin Jentzsch Tim Bierewirtz Ümit Hasirci Tim Rese Josef Seefeldt Sebastian Schimek Ulrich Kertzscher Christian Oliver Paschereit 《Indoor air》2021,31(6):1860-1873
The SARS-CoV-2 pandemic has created a great demand for a better understanding of the spread of viruses in indoor environments. A novel measurement system consisting of one portable aerosol-emitting mannequin (emitter) and a number of portable aerosol-absorbing mannequins (recipients) was developed that can measure the spread of aerosols and droplets that potentially contain infectious viruses. The emission of the virus from a human is simulated by using tracer particles solved in water. The recipients inhale the aerosols and droplets and quantify the level of solved tracer particles in their artificial lungs simultaneously over time. The mobile system can be arranged in a large variety of spreading scenarios in indoor environments and allows for quantification of the infection probability due to airborne virus spreading. This study shows the accuracy of the new measurement system and its ability to compare aerosol reduction measures such as regular ventilation or the use of a room air purifier. 相似文献
2.
Casalaro Giuseppina Lucia Cattivera Giulio Ciccozzi Federico Malavolta Ivano Wortmann Andreas Pelliccione Patrizio 《Software and Systems Modeling》2022,21(1):19-49
Software and Systems Modeling - Mobile robots operate in various environments (e.g. aquatic, aerial, or terrestrial), they come in many diverse shapes and they are increasingly becoming parts of... 相似文献
3.
4.
Esteban Vera Pingitore María Silvina Juárez Tomás Birgitt Wiese 《Drug development and industrial pharmacy》2015,41(6):942-952
Context: The administration of pharmabiotics is a promising alternative to antimicrobial drugs for the treatment and/or prevention of female urogenital infections.Objective: To design pharmabiotic formulations including bioactive ingredients of microbial origin combined with non-microbial substances and then to evaluate the stability of the combinations during freeze-drying and storage.Materials and methods: Different formulations including Lactobacillus gasseri CRL 1263, Lactobacillus salivarius CRL 1328, salivaricin CRL 1328 (a bacteriocin) and non-microbial compounds (lactose, inulin and ascorbic acid) were assayed, and the ingredients were freeze-dried together or separately. The formulations were stored in gelatin capsules at 4?°C for 360?d.Results: The viability of lactobacilli was affected to different extents depending on the strains and on the formulations assayed. L. salivarius and ascorbic acid were successfully combined only after the freeze-drying process. Salivaricin activity was not detected in formulations containing L. gasseri. However, when combined with ascorbic acid, lactose, inulin or L. salivarius, the bacteriocin maintained its activity for 360?d. The selected microorganisms proved to be compatible for their inclusion in multi-strain formulations together with lactose, inulin and ascorbic acid. Salivaricin could be included only in a L. salivarius CRL 1328 single-strain formulation together with non-microbial substances.Conclusions: This study provides new insights into the design of urogenital pharmabiotics combining beneficial lactobacilli, salivaricin CRL 1328 and compounds with different functionalities. 相似文献
5.
The fission yeast Schizosaccharomyces pombe is an important model organism for the study of fundamental questions in eukaryotic cell and molecular biology. A plethora of cellular processes are membrane associated and/or dependent on the proper functioning of cellular membranes. Phospholipids are not only the basic building blocks of cellular membranes; they also serve as precursors to numerous signaling molecules. In this review, we describe the biosynthetic pathways leading to major S. pombe phospholipids, how these pathways are regulated, and what is known about degradation and turnover of fission yeast phospholipids. This review also addresses the synthesis, regulation and the role of water-soluble phospholipid precursors. The last chapter of the review is devoted to the use of S. pombe for the biotechnological production of value-added lipid molecules. 相似文献
6.
7.
8.
Non-pinched, minimum energy solutions are important class of distillation designs that offer the potential advantage of a better trade-off between capital investment and operating costs. In this paper, two important tasks associated with non-pinched distillation designs are studied. Thus the novel contributions of this work to the literature are
- (1) A comprehensive methodology for finding non-pinched minimum energy designs.
- (2) Understanding of the reasons for the existence of non-pinched distillation designs.
9.
Lavrenko Vladimir A. Shvets Vera A. Talash Viktor N. 《Powder Metallurgy and Metal Ceramics》2004,43(1-2):62-66
The corrosion properties of TiCN, TiCN – AlN, and (TiCN – AlN) – (Fe – Cr) ceramics as well as those of the individual components TiN and TiC in a 3% NaCl solution have been investigated. The kinetics and the mechanism of anode dissolution of metals and oxidation of specimens have been studied by using polarization curves, chemical and x-ray phase analyses, Auger electron spectroscopy, and scanning electron microscopy (SEM). TiCN and TiCN – AlN composites have been found to be the most corrosion-resistant. The presence of a metallic binder in the titanium carbon nitride somewhat decreases the corrosion resistance of the ceramics. On the whole, however, the ceramics developed boast a significantly higher corrosion resistance than that of structural steel. 相似文献
10.
This paper presents a summary of the mechanical features and the medium term operating experience from three small horizontal axis wind energy conversion systems covering a range of 500 to 5000 Watt, intented for rural and isolated communities. These turbines have a new regulator which reduces gyroscopic loads, is easy to adjust and could be manufactured stronger and in smaller sizes than the conventional tail vanes. It is concluded that is feasible to build cheaps and reliable wind turbine generators with an acceptable efficiency employing common-use elements, but is needed a careful and optimized design. 相似文献