全文获取类型
收费全文 | 4402篇 |
免费 | 309篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 50篇 |
综合类 | 6篇 |
化学工业 | 853篇 |
金属工艺 | 219篇 |
机械仪表 | 317篇 |
建筑科学 | 56篇 |
能源动力 | 158篇 |
轻工业 | 357篇 |
水利工程 | 17篇 |
石油天然气 | 2篇 |
无线电 | 853篇 |
一般工业技术 | 957篇 |
冶金工业 | 289篇 |
原子能技术 | 61篇 |
自动化技术 | 526篇 |
出版年
2024年 | 5篇 |
2023年 | 69篇 |
2022年 | 90篇 |
2021年 | 138篇 |
2020年 | 102篇 |
2019年 | 114篇 |
2018年 | 169篇 |
2017年 | 148篇 |
2016年 | 164篇 |
2015年 | 127篇 |
2014年 | 229篇 |
2013年 | 302篇 |
2012年 | 285篇 |
2011年 | 343篇 |
2010年 | 232篇 |
2009年 | 273篇 |
2008年 | 222篇 |
2007年 | 200篇 |
2006年 | 198篇 |
2005年 | 156篇 |
2004年 | 148篇 |
2003年 | 131篇 |
2002年 | 118篇 |
2001年 | 105篇 |
2000年 | 71篇 |
1999年 | 68篇 |
1998年 | 133篇 |
1997年 | 71篇 |
1996年 | 60篇 |
1995年 | 44篇 |
1994年 | 40篇 |
1993年 | 33篇 |
1992年 | 23篇 |
1991年 | 10篇 |
1990年 | 17篇 |
1989年 | 14篇 |
1988年 | 8篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 4篇 |
1984年 | 11篇 |
1983年 | 5篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有4721条查询结果,搜索用时 15 毫秒
101.
Evaluation of chloride penetration in high performance concrete using neural network algorithm and micro pore structure 总被引:2,自引:0,他引:2
Chloride attack is one of the major causes of deterioration of reinforced concrete structures. In order to evaluate the chloride behavior in concrete, a reasonable prediction for the diffusion coefficient of chloride ion, which governs mechanism of chloride diffusion inside concrete, is basically required. However, it is difficult to obtain chloride diffusion coefficients from experiments due to time and cost limitations.In this study, a numerical technique for chloride diffusion in high performance concrete (HPC) using a neural network algorithm is proposed. In order to collect comparative data on diffusion coefficients in concrete with various mineral admixtures such as ground granulated blast-furnace slag (GGBFS), fly ash (FA), and silica fume (SF), a series of electrically driven chloride penetration tests was performed. Seven material components in various mix designs and duration time are selected as neurons in a back-propagation algorithm, and associated learning of the neural network is carried out. An evaluation technique for chloride behavior in HPC using the obtained diffusion coefficients from the neural network algorithm is developed based on, so-called, Multi-Component Hydration Heat Model (MCHHM) and Micro Pore Structure Formation Model (MPSFM). The applicability of the developed technique is verified by comparing the analytical simulation results and the experimental results obtained in this study. Furthermore, this proposed technique using the neural network algorithm and micro modeling is applied to available experimental data for verification of its applicability. 相似文献
102.
Sung Hwan Yoon Jeong Park Oh Boong Kwon Jin Han Yoon Sang In Keel Jeong S. Kim Dae S. Bae 《Fuel》2012,91(1):51-60
Laminar lifted butane flames diluted with nitrogen have been investigated experimentally to determine distinctive self-excitation regimes in the flame stability maps and also to elucidate the individual self-excitation characteristics. Self-excitations of lift-off height are classified into five regimes in laminar free-jet lift-off butane flames diluted with nitrogen: a stationary lifted regime (regime I), a heat-loss-induced self-excitation (regime II), a buoyancy-induced self-excitation due to flame flicker as well as a heat-loss-induced self-excitation (III), a combined form of an oscillation prior to blow-out and a heat-loss-induced oscillation (regime IV), and a combined form of an buoyancy-induced self-excitation and a heat-loss-induced oscillation as well as an additional buoyancy-driven self-excitation due to flame flicker (regime V). Extremely low-frequency (<0.1 Hz) self-excitation is caused by conductive heat loss from the premixed wings to the trailing diffusion flame and can be explained by a proposed mechanism. It is also found that the flame oscillation prior to flame blow-out is also caused by buoyancy and also significantly affected by the conductive heat loss from the premixed wings to the trailing diffusion flame, thereby showing that the frequency with nozzle exit velocity increases in the triple-flame propagation mode and then decreases in the flame-front propagation mode. Characterization of the individual self-excitation mode is presented and also discussed with Strouhal numbers and its relevant parameters through the analysis of power spectrum for temporal variation of lift-off height. 相似文献
103.
Dong Won Lee Young Dug Bae Suk Kwon Kim Bong Guen Hong Hyun Kyu Jung Jeong Yong Park Yong Hwan Jeong Byung Kwon Choi 《Fusion Engineering and Design》2009,84(7-11):1160-1163
In order to verify the integrity of the first wall (FW) of the International Thermonuclear Experimental Reactor (ITER), especially for preparing its qualification program by ITER-O, Be/Cu/SS mock-ups, which were the same size as the qualification mock-ups, were fabricated and tested at the TSEFEY, an e-beam facility, in Efremov, Russia. These mock-ups were joined with a 316 L austenitic stainless steel (SS316L) block for a structural material, CuCrZr for a heat sink material and SS316L tubes for a coolant and then, joined with three Be tiles for an armor material. A hot isostatic pressing (HIP) was used as manufacturing methods at a 1050 °C, 100 MPa for 2 h for a Cu/SS joining and at a 580 °C, 100 MPa for 2 h for a Be/(Cu/SS) joining. Two mock-ups were fabricated by using 1 μmCr/10 μmCu of an interlayer between the Be tile and Cu block. The high heat flux (HHF) tests were performed at 1.5 and 2.0 MW/m2 heat fluxes for each mock-up. The given conditions and the expected fatigue lifetime were evaluated from a preliminary analysis with ANSYS. Both mock-ups survived for up to 1000 and 268 cycles at 1.5 and 2.0 MW/m2 heat fluxes, respectively. They are higher than the expected numbers of cycles to a failure. 相似文献
104.
Naoki Motomura Yuto Yamazaki Daiki Koga Shogo Harashima Xin Gao Yuta Tezuka Kei Omata Yoshikiyo Ono Ryo Morimoto Fumitoshi Satoh Yasuhiro Nakamura Go Eun Kwon Man Ho Choi Akihiro Ito Hironobu Sasano 《International journal of molecular sciences》2022,23(4)
Cortisol-producing adenoma (CPA) is composed of clear and compact cells. Clear cells are lipid abundant, and compact ones lipid poor but associated with higher production of steroid hormones. PRKACA mutation (PRKACA mt) in CPA patients was reported to be associated with more pronounced clinical manifestation of Cushing’s syndrome. In this study, we examined the association of histological features and genotypes with cholesterol uptake receptors and synthetic enzymes in 40 CPA cases, and with the quantitative results obtained by gas chromatography-mass spectrometry (GC-MS) analysis in 33 cases to explore their biological and clinical significance. Both cholesterol uptake receptors and synthetic enzymes were more abundant in compact cells. GC-MS analysis demonstrated that the percentage of compact cells was inversely correlated with the concentrations of cholesterol and cholesterol esters, and positively with the activity of cholesterol biosynthesis from cholesterol esters. In addition, hormone-sensitive lipase (HSL), which catalyzes cholesterol biosynthesis from cholesterol esters, tended to be more abundant in compact cells of PRKACA mt CPAs. These results demonstrated that both cholesterol uptake and biosynthesis were more pronounced in compact cells in CPA. In addition, more pronounced HSL expression in compact cells of PRKACA mt CPA could contribute to their more pronounced clinical manifestation. 相似文献
105.
Lee So-Yeon Kwon Ki-Hyun Chai Changhoon Oh Se-Wook 《Food science and biotechnology》2018,27(2):599-605
Food Science and Biotechnology - This study was conducted to compare the growth parameters of Listeria monocytogenes between beef isolates and Type strains in raw beef. Beef was artificially... 相似文献
106.
Lee Sokjoon Seo Hwajeong Kwon Hyeokchan Yoon Hyunsoo 《The Journal of supercomputing》2019,75(8):4329-4349
The Journal of Supercomputing - Since the advent of deep belief network deep learning technology in 2006, artificial intelligence technology has been utilized in various convergence areas, such as... 相似文献
107.
Young Chul Han Song Lee Hae Woong Kwon Young Soo Kang 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,260(2):599-602
We report on how γ-ray irradiation affects the magnetic properties of a powder sample of Nd–Fe–B, which was irradiated at room temperature with doses up to 700 kGy. Both the magnetic properties and surface morphology were changed by the effects of the γ-ray irradiation. The unirradiated and irradiated samples were then characterized using the VSM, XRD and SEM techniques. 相似文献
108.
Wireless Personal Communications - This paper presents an error detection algorithm for Lempel-Ziv-78 (LZ78) compressed data. LZ78 data compression involves dictionary coding and aims to compress... 相似文献
109.
110.
Hyun Shin Yeon Hee Ha Hyun‐Gu Kim Ran Kim Soon‐Ki Kwon Yun‐Hi Kim Jang‐Joo Kim 《Advanced materials (Deerfield Beach, Fla.)》2019,31(21)
Deep‐blue emitting Iridium (Ir) complexes with horizontally oriented emitting dipoles are newly designed and synthesized through engineering of the ancillary ligand, where 2′,6′‐difluoro‐4‐(trimethylsilyl)‐2,3′‐bipyridine (dfpysipy) is used as the main ligand. Introduction of a trimethylsilyl group at the pyridine and a nitrogen at the difluoropyrido group increases the bandgap of the emitter, resulting in deep‐blue emission. Addition of a methyl group (mpic) to a picolinate (pic) ancillary ligand or replacement of an acetate structure of pic with a perfluoromethyl‐triazole structure (fptz) increases the horizontal component of the emitting dipoles in sequence of mpic (86%) > fptz (77%) > pic (74%). The organic light‐emitting diode (OLED) using the Ir complex with the mpic ancillary ligand shows the highest external quantum efficiency (31.9%) among the reported blue OLEDs with a y‐coordinate value lower than 0.2 in the 1931 Commission Internationale de L'Eclairage (CIE) chromaticity diagram. 相似文献