全文获取类型
收费全文 | 1377篇 |
免费 | 70篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 20篇 |
综合类 | 5篇 |
化学工业 | 305篇 |
金属工艺 | 39篇 |
机械仪表 | 40篇 |
建筑科学 | 39篇 |
矿业工程 | 7篇 |
能源动力 | 72篇 |
轻工业 | 59篇 |
水利工程 | 9篇 |
石油天然气 | 2篇 |
无线电 | 194篇 |
一般工业技术 | 251篇 |
冶金工业 | 167篇 |
原子能技术 | 16篇 |
自动化技术 | 228篇 |
出版年
2023年 | 21篇 |
2022年 | 30篇 |
2021年 | 40篇 |
2020年 | 40篇 |
2019年 | 41篇 |
2018年 | 52篇 |
2017年 | 40篇 |
2016年 | 52篇 |
2015年 | 36篇 |
2014年 | 40篇 |
2013年 | 99篇 |
2012年 | 66篇 |
2011年 | 75篇 |
2010年 | 36篇 |
2009年 | 58篇 |
2008年 | 57篇 |
2007年 | 49篇 |
2006年 | 21篇 |
2005年 | 35篇 |
2004年 | 31篇 |
2003年 | 26篇 |
2002年 | 19篇 |
2001年 | 19篇 |
2000年 | 16篇 |
1999年 | 12篇 |
1998年 | 47篇 |
1997年 | 28篇 |
1996年 | 24篇 |
1995年 | 20篇 |
1994年 | 19篇 |
1993年 | 22篇 |
1992年 | 21篇 |
1991年 | 15篇 |
1990年 | 14篇 |
1989年 | 11篇 |
1988年 | 19篇 |
1987年 | 14篇 |
1986年 | 17篇 |
1985年 | 22篇 |
1984年 | 21篇 |
1983年 | 11篇 |
1982年 | 17篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1978年 | 9篇 |
1977年 | 9篇 |
1976年 | 10篇 |
1974年 | 6篇 |
1973年 | 9篇 |
1971年 | 7篇 |
排序方式: 共有1453条查询结果,搜索用时 31 毫秒
51.
β-Ga2O3 nanobelts were synthesized using a vapor transport process in a controlled ambient. Structural characterization revealed that the as-synthesized samples consisted of monoclinic β-Ga2O3 nanobelts, and the presence of gallium-associated defects was verified using cathodoluminescence (CL). The formation of gallium-associated defects was explained by the insufficiency of the supply of cations, generating gallium vacancies on the (010) facet during growth. Furthermore, field-emission measurements indicated that β-Ga2O3 nanobelts exhibited defect-related electron emission. The turn-on fields of β-Ga2O3 nanobelts increased significantly with the degree of structural defects. For a sample prepared under 15% ambient oxygen, Fowler–Nordheim (F–N) analysis revealed two distinct field-enhancement factors of 1194 and 276, respectively. A correlation between field emission and structural defects was proposed. The experimental results demonstrate the presence of gallium-associated defects, which behave as electron traps, degrading the electron field-emission properties of β-Ga2O3 nanobelts. 相似文献
52.
53.
Applied Intelligence - Traffic forecasting plays an important role of modern Intelligent Transportation Systems (ITS). With the recent rapid advancement in deep learning, graph neural networks... 相似文献
54.
Nguyen T. H. Hanh Bui T. Nhung Le T. Hop Le T. Tuyet Duong T. A. Dao Nguyen T. T. Thu Tran Quang Binh 《Lipids》2020,55(6):683-691
Apolipoprotein A-V encoded by apolipoprotein 5 (APOA5) gene plays an important role in lipid metabolism, especially in the regulation of plasma triglycerol levels. The study aimed to evaluate the association of the APOA5-rs662799 polymorphism with dyslipidemia in Vietnamese children and the potential modification of obesity-related traits (body mass index, waist circumference, hip circumference, and waist-to-hip ratio) on this association. A case–control study was conducted with a total of 154 dyslipidemia cases and 389 controls at the age of 6 to 10 recruited at 31 primary schools in Hanoi city of Vietnam. Genotype for APOA5-rs662799 polymorphism was determined by the restriction fragment length polymorphism analysis. The association of APOA5-rs662799 polymorphism with dyslipidemia adjusting for age, sex, residence, and obesity-related traits was analyzed by binary logistic regression analysis. The results showed that in comparison with T/T and T/C carriers, the C/C carriers had a higher concentration of serum TAG in cases (p =0.049). Carriers of the C allele (C/C + T/C) had higher risk for developing dyslipidemia and hypertriglyceridemia than subjects with T/T genotype (odds ratio, OR = 1.7, p =0.0062 and OR = 1.6, p = 0.026, respectively). The association remained significant after adjusting for age, gender, residence, and obesity status (OR = 1.75, p = 0.006 and OR = 1.53, p = 0.049, respectively) or other obesity-related traits. The study suggested that the APOA5-rs662799 polymorphism may be a determinant of dyslipidemia and hypertriglyceridemia in Vietnamese children, independent of obesity-related traits. 相似文献
55.
Phuong Linh Nguyen Bich Phuong Bui Heesoon Lee Jungsook Cho 《International journal of molecular sciences》2021,22(5)
Novel 1,8-naphthyridine-2-carboxamide derivatives with various substituents (HSR2101-HSR2113) were synthesized and evaluated for their effects on the production of pro-inflammatory mediators and cell migration in lipopolysaccharide (LPS)-treated BV2 microglial cells. Among the tested compounds, HSR2104 exhibited the most potent inhibitory effects on the LPS-stimulated production of inflammatory mediators, including nitric oxide (NO), tumor necrosis factor-α, and interleukin-6. Therefore, this compound was chosen for further investigation. We found that HSR2104 attenuated levels of inducible NO synthase and cyclooxygenase 2 in LPS-treated BV2 cells. In addition, it markedly suppressed LPS-induced cell migration as well as the generation of intracellular reactive oxygen species (ROS). Moreover, HSR2104 abated the LPS-triggered nuclear translocation of nuclear factor-κB (NF-κB) through inhibition of inhibitor kappa Bα phosphorylation. Furthermore, it reduced the expressions of Toll-like receptor 4 (TLR4) and myeloid differentiation factor 88 (MyD88) in LPS-treated BV2 cells. Similar results were observed with TAK242, a specific inhibitor of TLR4, suggesting that TLR4 is an upstream regulator of NF-κB signaling in BV2 cells. Collectively, our findings demonstrate that HSR2104 exhibits anti-inflammatory and anti-migratory activities in LPS-treated BV2 cells via the suppression of ROS and TLR4/MyD88/NF-κB signaling pathway. Based on our observations, HSR2104 may have a beneficial impact on inflammatory responses and microglial cell migration involved in the pathogenesis of various neurodegenerative disorders. 相似文献
56.
Lei Zhao Tien Duy Vo Marcel Kaiser Prof. Dr. Helge B. Bode 《Chembiochem : a European journal of chemical biology》2020,21(9):1288-1292
A new cyclic lipopeptide, phototemtide A ( 1 ), was isolated from Escherichia coli expressing the biosynthetic gene cluster pttABC from Photorhabdus temperata Meg1. The structure of 1 was elucidated by HR-ESI-MS and NMR experiments. The absolute configurations of amino acids and 3-hydroxyoctanoic acid in 1 were determined by using the advanced Marfey's method and comparison after total synthesis of 1 , respectively. Additionally, three new minor derivatives, phototemtides B–D ( 2 – 4 ), were identified by detailed HPLC–MS analysis. Phototemtide A ( 1 ) showed weak antiprotozoal activity against Plasmodium falciparum, with an IC50 value of 9.8 μm . The biosynthesis of phototemtides A–D ( 1 – 4 ) was also proposed. 相似文献
57.
Anh Thi Hong Bui Daniel Cozzolino Bogdan Zisu Jayani Chandrapala 《International Journal of Food Science & Technology》2021,56(8):3948-3959
The effects of low-frequency ultrasound on the production of volatile compounds in model casein protein systems containing various fat concentrations of 2%, 4% and 6% (w/w) were investigated. Ultrasound application was performed at 20 kHz for up to 10 min which corresponded to energy densities ranging from 9.54 to 190.8 J mL−1. Similar volatile compounds were detected both in pure fat and mixtures of casein and fat (CF) systems. These volatiles belonged to the groups of aldehydes, ketones, esters, alcohols and hydrocarbons, which were the products of oxidation of lipids or protein degradation due to acoustic cavitation. The amount of fat in the casein systems had minor effects on the production of volatiles, whereas the production of volatile compounds was significantly affected by the ultrasound treatment. Short sonication times <5 min generated similar volatile profiles to the untreated samples. In contrast, prolonged sonication for 5 and 10 min considerably increased the production of volatile compounds and the amounts of fatty acids. Thus, the application of low–frequency ultrasound for short periods should be considered to minimise the production of volatile compounds which can ultimately affect the taste. 相似文献
58.
Kuo-Hsiung Tseng Juei-Long Chiu Heng-Lin Lee Yi-Syuan Kao Der-Chi Tien 《Materials and Manufacturing Processes》2016,31(2):186-193
This study developed a system monitoring the electric discharge machine's (EDM) discharge energy and success rate to replace conventional oscilloscope observation. By using logic circuit, the signals are transmitted to the PC monitoring platform in order to display the discharge success times, discharge success rate, and electrode's consumption energy. The advantage of the proposed system is the capability to observe real-time discharges and record the experimental conditions, as well as optimize the discharge parameter settings. The experimental results suggest that, in the preparation of nanosilver colloid, the cost-performance of Ton–Toff at 10–100 µs is the optimal setting. The monitoring system also can take advantage of the discharge success rate to control the energy consumption of the electrode to obtain the standardization of products. The results suggest that, while discharge success rate, electrode's weight loss and wavelength of the absorption peak are considerably accurate, but concentration accuracy is relatively poor. The discharge success rate monitoring system is an innovative method that can help to realize electric discharge processing, optimize product quality, and it may be a powerful processing tool in the future. 相似文献
59.
Abstract A numerical technique for integrating the full Navier‐Stokes and diffusion equations through an initial value problem has been used to investigate the time development of a line buoyant source issuing in a density‐stratified environment. The basic physical features and some structures of the interactions of the motion at the intermediate mixing region are obtained. Results show that the stratification tends to inhibit the flow development of the buoyant source and to encourage the formation of a recirculatory vortex on the lower region near the source and the upper region. 相似文献
60.