全文获取类型
收费全文 | 2496篇 |
免费 | 80篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 44篇 |
综合类 | 2篇 |
化学工业 | 273篇 |
金属工艺 | 42篇 |
机械仪表 | 32篇 |
建筑科学 | 52篇 |
能源动力 | 21篇 |
轻工业 | 175篇 |
水利工程 | 19篇 |
石油天然气 | 6篇 |
无线电 | 82篇 |
一般工业技术 | 172篇 |
冶金工业 | 1557篇 |
原子能技术 | 11篇 |
自动化技术 | 92篇 |
出版年
2023年 | 7篇 |
2022年 | 18篇 |
2021年 | 44篇 |
2020年 | 24篇 |
2019年 | 41篇 |
2018年 | 40篇 |
2017年 | 53篇 |
2016年 | 27篇 |
2015年 | 32篇 |
2014年 | 39篇 |
2013年 | 79篇 |
2012年 | 65篇 |
2011年 | 81篇 |
2010年 | 55篇 |
2009年 | 60篇 |
2008年 | 31篇 |
2007年 | 51篇 |
2006年 | 49篇 |
2005年 | 49篇 |
2004年 | 26篇 |
2003年 | 26篇 |
2002年 | 18篇 |
2001年 | 23篇 |
2000年 | 20篇 |
1999年 | 71篇 |
1998年 | 475篇 |
1997年 | 270篇 |
1996年 | 201篇 |
1995年 | 93篇 |
1994年 | 91篇 |
1993年 | 86篇 |
1992年 | 14篇 |
1991年 | 22篇 |
1990年 | 29篇 |
1989年 | 33篇 |
1988年 | 23篇 |
1987年 | 15篇 |
1986年 | 22篇 |
1985年 | 13篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 9篇 |
1980年 | 16篇 |
1978年 | 3篇 |
1977年 | 37篇 |
1976年 | 82篇 |
1975年 | 5篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有2580条查询结果,搜索用时 775 毫秒
71.
72.
David Deibe Margarita Amor Ramón Doallo David Miranda Miguel Cordero 《International journal of remote sensing》2017,38(3):827-849
In recent years lidar technology has experienced a noticeable increase in its relevance and usage in a number of scientific fields. Therefore, software capable of handling lidar data becomes a key point in those fields. In this article, we present GPU-based viewer lidar (GVLiDAR), a novel web framework for visualization and geospatial measurement of lidar data point sets. The design of the framework is focused on achieving three key objectives: performance in terms of real-time interaction, functionality, and online availability for the lidar datasets. All lidar files are pre-processed and stored in a lossless data structure, which minimizes transfer requirements and offers an on-demand lidar data web framework. 相似文献
73.
Long‐term expansion of human induced pluripotent stem cells in a microcarrier‐based dynamic system
下载免费PDF全文
![点击此处可从《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
74.
D. Pereira J. Gandra J. Pamies-Teixeira R.M. Miranda P. Vilaça 《Journal of Materials Processing Technology》2014,214(12):2858-2868
Friction surfacing was performed to produce multi-layer coatings of AISI 1024, AISI 1045 and AISI H13 over mild steel substrates where a continuous joining was achieved between adjacent layers and between the clad and the substrate. Microscopic and hardness characterization revealed the presence of bainitic and martensitic microstructures which influenced the hardness of the coatings. The study aimed to determine which material combination was more wear-resistant. The analysis suggested that AISI 1024 presents the least wear, both in terms of friction coefficient and wear rate. This is due to the formation of adherent protective oxide layer which is not present in both the AISI 1045 and AISI H13 steels. 相似文献
75.
The linear thermal expansions (LTE) of bulk nanocrystalline ingot iron (BNII) at six directions on rolling plane and conventional
polycrystalline ingot iron (CPII) at one direction were measured from liquid nitrogen temperature to 300 K. Although the volume
fraction of grain boundary and residual strain of BNII are larger than those of CPII, LTE of BNII at the six measurement directions
were less than those of CPII. This phenomenon could be explained with Morse potential function and the crystalline structure
of metals. Our LTE results ruled out that the grain boundary and residual strain of BNII did much contribution to its thermal
expansion. The higher interaction potential energy of atoms, the less partial derivative of interaction potential energy with
respect to temperature T and the porosity free at the grain boundary of BNII resulted in less LTE in comparison with CPII from liquid nitrogen temperature
to 300 K. The higher LTE of many bulk nanocrystalline materials resulted from the porosity at their grain boundaries. However,
many authors attributed the higher LTE of many nanocrystalline metal materials to their higher volume fraction of grain boundaries. 相似文献
76.
F. Kahleyss R. Lima de Miranda T. Surmann C. Zamponi C. Machai D. Biermann E. Quandt 《Journal of Materials Engineering and Performance》2011,20(4-5):500-505
Nowadays, many manufacturing processes require the machining of complex forms with a high aspect ratio or cavities. Tools with a long overhang length are a common method to meet these requirements. Typical examples for this are boring bars for bore-turning and the milling with very long cutters. These tools tend to vibrate strongly due to their slender shape. The stress-induced transformation of austenite to martensite and the distinctive hysteresis loop allow the NiTi shape memory alloys (SMA) to absorb vibration energy. This article describes the innovative approach to dampen process vibrations by coating the tool shafts of cutting tools with long overhang with NiTi thin films. It explores how these thin films can be applied on polished tungsten carbide shafts and how their modal parameters are modified by these coatings. In a further step, this knowledge is used to calculate stability charts of corresponding machining processes. The study reported in this article identified the stabilizing effects of coatings with a thickness of 2-4 ??m on milling processes. The minimum stability limit was increased by up to 200%. 相似文献
77.
Ray Lara A.; Miranda Robert Jr.; MacKillop James; McGeary John; Tidey Jennifer W.; Rohsenow Damaris J.; Gwaltney Chad; Swift Robert W.; Monti Peter M. 《Canadian Metallurgical Quarterly》2009,17(2):122
Topiramate, an anticonvulsant medication, is an efficacious treatment for alcohol dependence. To date, little is known about genetic moderators of side effects from topiramate. The objective of this study was to examine 3 single nucleotide polymorphisms (SNPs) of the glutamate receptor GluR5 gene (GRIK1) as predictors of topiramate-induced side effects in the context of a laboratory study of topiramate. Heavy drinkers (n = 51, 19 women and 32 men), 75% of whom met criteria for an alcohol use disorder, completed a 5-week dose escalation schedule to a target dose of either 200 or 300 mg or matched placebo. The combined medication groups were compared with placebo-treated individuals for side effects at target dose. Analyses revealed that an SNP in intron 9 of the GRIK1 gene (rs2832407) was associated with the severity of topiramate-induced side effects and with serum levels of topiramate. Genes underlying glutamatergic neurotransmission, such as the GRIK1 gene, may help predict heterogeneity in topiramate-induced side effects. Future studies in larger samples are needed to more fully establish these preliminary findings. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
78.
79.
80.
Roseli de Souza Santos da Costa Flavia da Silva Santos Daniela de Barros Mucci Tânia Vignuda de Souza Fátima Lucia de Carvalho Sardinha Célia Regina Moutinho de Miranda Chaves Maria das Graças Tavares do Carmo 《Lipids》2016,51(12):1363-1373
The purpose of this study was to investigate the trans fatty acids (TFA) content and distribution in colostrum, mature milk, and diet of adolescent mothers, after TFA declaration in food labels became mandatory in Brazil. Participants were healthy adolescents (n 54, 15–19 years, 1–90 days postpartum) practicing exclusive breastfeeding. Milk samples were collected 3 days after delivery (colostrum) and in the third month postpartum (mature milk) by hand expression. The fatty acid composition of the milk samples was determined by gas chromatography. TFA intake corresponded to 1.23 % of total energy value. Total 18:2 TFA accounted for less than 0.5 % of the energy intake. The amount of total 18:1 TFA (mean ± SEM) was 1.9 % ± 0.14 in colostrum and 1.5 % ± 0.2 in mature milk. The total content of n‐3 PUFA was inversely correlated with the total content of 18:1 TFA in colostrum. Both in colostrum and in mature milk, vaccenic acid (11t‐18:1) was found to be the most abundant 18:1 trans isomer, followed by elaidic acid (9t‐18:1), whereas rumenic acid (9c,11t‐18:2 CLA) was the predominant 18:2 trans isomer. In conclusion, the levels of TFA of industrial sources found in the mother's diet and breast milk (colostrum and mature milk) showed a decrease in relation to those observed in studies conducted prior to the TFA labeling resolution in Brazil. However, the current low intake levels of n‐3 LCPUFA and DHA content in the milk of lactating adolescents may be insufficient for supporting adequate neurological development of the infants. 相似文献