全文获取类型
收费全文 | 2184篇 |
免费 | 127篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 20篇 |
综合类 | 2篇 |
化学工业 | 515篇 |
金属工艺 | 33篇 |
机械仪表 | 47篇 |
建筑科学 | 80篇 |
矿业工程 | 4篇 |
能源动力 | 95篇 |
轻工业 | 249篇 |
水利工程 | 36篇 |
石油天然气 | 10篇 |
无线电 | 171篇 |
一般工业技术 | 326篇 |
冶金工业 | 233篇 |
原子能技术 | 14篇 |
自动化技术 | 484篇 |
出版年
2024年 | 4篇 |
2023年 | 29篇 |
2022年 | 33篇 |
2021年 | 110篇 |
2020年 | 78篇 |
2019年 | 65篇 |
2018年 | 69篇 |
2017年 | 75篇 |
2016年 | 79篇 |
2015年 | 79篇 |
2014年 | 66篇 |
2013年 | 152篇 |
2012年 | 155篇 |
2011年 | 157篇 |
2010年 | 105篇 |
2009年 | 113篇 |
2008年 | 99篇 |
2007年 | 101篇 |
2006年 | 92篇 |
2005年 | 77篇 |
2004年 | 63篇 |
2003年 | 42篇 |
2002年 | 52篇 |
2001年 | 28篇 |
2000年 | 16篇 |
1999年 | 27篇 |
1998年 | 56篇 |
1997年 | 39篇 |
1996年 | 23篇 |
1995年 | 18篇 |
1994年 | 16篇 |
1993年 | 18篇 |
1992年 | 8篇 |
1991年 | 14篇 |
1990年 | 8篇 |
1989年 | 18篇 |
1988年 | 8篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 15篇 |
1979年 | 4篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1974年 | 7篇 |
1972年 | 4篇 |
排序方式: 共有2319条查询结果,搜索用时 31 毫秒
101.
102.
Feedforward control application in aerobic and anoxic biotrickling filters for H2S removal from biogas 下载免费PDF全文
103.
Gabriel Rinnerthaler Hubert Hackl Simon Peter Gampenrieder Frank Hamacher Clemens Hufnagl Cornelia Hauser-Kronberger Franz Zehentmayr Gerd Fastner Felix Sedlmayer Brigitte Mlineritsch Richard Greil 《International journal of molecular sciences》2016,17(2)
For quantitative microRNA analyses in formalin-fixed paraffin-embedded (FFPE) tissue, expression levels have to be normalized to endogenous controls. To investigate the most stably-expressed microRNAs in breast cancer and its surrounding tissue, we used tumor samples from primary tumors and from metastatic sites. MiRNA profiling using TaqMan® Array Human MicroRNA Cards, enabling quantification of 754 unique human miRNAs, was performed in FFPE specimens from 58 patients with metastatic breast cancer. Forty-two (72%) samples were collected from primary tumors and 16 (28%) from metastases. In a cross-platform analysis of a validation cohort of 32 FFPE samples from patients with early breast cancer genome-wide microRNA expression analysis using SurePrintG3 miRNA (8 × 60 K)® microarrays from Agilent® was performed. Eleven microRNAs could be detected in all samples analyzed. Based on NormFinder and geNorm stability values and the high correlation (rho ≥ 0.8) with the median of all measured microRNAs, miR-16-5p, miR-29a-3p, miR-126-3p, and miR-222-3p are suitable single gene housekeeper candidates. In the cross-platform validation, 29 human microRNAs were strongly expressed (mean log2-intensity > 10) and 21 of these microRNAs including miR-16-5p and miR-29a-3p were also stably expressed (CV < 5%). Thus, miR-16-5p and miR-29a-3p are both strong housekeeper candidates. Their Normfinder stability values calculated across the primary tumor and metastases subgroup indicate that miR-29a-3p can be considered as the strongest housekeeper in a cohort with mainly samples from primary tumors, whereas miR-16-5p might perform better in a metastatic sample enriched cohort. 相似文献
104.
María Dolores López‐Ramírez Ulises Miguel García‐Ventura Fabricio Omar Barroso‐Muñoz Juan Gabriel Segovia‐Hernández Salvador Hernández 《化学工程与技术》2016,39(2):271-275
The esterification of oleic acid and methanol using sulfuric acid as a homogeneous catalyst is studied in reactive‐separation systems. The conversion of the free fatty acid was investigated in two different experiments with the molar ratio of methanol/oleic acid, amount of catalyst, temperature, and reaction time as variables. The conversion of the free fatty acid was found to depend strongly on the molar ratio of methanol/oleic acid. The reaction time had a direct effect on the conversion of the free fatty acid, and this conversion decreased with higher temperature. These results were valuable for a preliminary study on biodiesel production, using an acid homogeneous catalyst in a reactive dividing‐wall distillation column. 相似文献
105.
The preparation of new compounds, 1,1‐bis[4‐(2‐(4,4‐dimethyl‐1,3‐oxazolyl))phenyl]ethanol and a new symmetrically disubstituted 1,1‐diphenylethylene derivative, 1,1‐bis[4‐(2‐(4,4‐dimethyl‐1,3‐oxazolyl))phenyl]ethylene, is described. 1,1‐Bis[4‐(2‐(4,4‐dimethyl‐1,3‐oxazolyl))phenyl]ethylene was utilized as a dioxazolyl initiator precursor for the polymerization of styrene by atom transfer radical polymerization (ATRP) methods to produce α‐bis(oxazolyl) polystyrene. The kinetic study of the polymerization process indicated that the free radical polymerization reaction for the preparation of α‐bis(oxazolyl) polystyrene follows first‐order rate kinetics with respect to monomer consumption. α,ω‐Tetrakis(oxazolyl) polystyrene was prepared by a new, in situ, controlled/living, post‐ATRP chain‐end‐functionalization reaction which involves the direct addition of 1,1‐bis[4‐(2‐(4,4‐dimethyl‐1,3‐oxazolyl))phenyl]ethylene to the ω‐terminus of the α‐bis(oxazolyl) polystyrene derivative, without the isolation and purification of the polymeric precursor. α‐Bis(carboxyl) and α,ω‐tetrakis(carboxyl) polystyrene derivatives were obtained by the quantitative chemical transformation of the oxazoline groups of the respective aromatic oxazolyl chain‐end‐functionalized polystyrene derivatives to the aromatic carboxyl groups. The organic precursor compounds, the dioxazolyl‐functionalized 1,1‐diphenylethylene derivative and the functionalized polymers were characterized using 1H NMR and 13C NMR spectrometry and Fourier transform infrared spectroscopy, size‐exclusion and thin‐layer chromatography and non‐aqueous titration measurements. © 2014 Society of Chemical Industry 相似文献
106.
107.
The main weakness of elastic optical networks (EON), under dynamic traffic conditions, stems from spectrum fragmentation. A lot of research efforts have been dedicated during recent years to spectrum defragmentation. In this work, a thorough study about proactive defragmentation is carried out. Effects of the different defragmentation parameters on the EON performance are analyzed, and appropriate values of the defragmentation period, which guarantee suitable network performance while keeping the network control complexity at reasonable values, are obtained by means of extensive simulations. Benefit obtained by applying different defragmentation strategies, in terms of increase in the supported load at a given bandwidth blocking probability, is also reported. Different traffic conditions and network topologies are simulated to assess the validity of the obtained results. 相似文献
108.
109.
Gabriel Kroiz 《Journal of Architectural Education》2013,67(2):205-213
This study will look at the education of black architects in the undergraduate Architecture and Environmental Design Program (BSAED) at Morgan State University (MSU) relative to the vision of its founding director, Melvin Mitchell. Though retiring shortly after the start of the program in 2001, Mitchell left on the shelf his book The Crisis of the African-American Architect, which included a manifesto for educating black architects for the 21st century. Examining Mitchell's book provides for an evaluation of the current program and pedagogy, relative to Mitchell's vision of the future of black architecture and black architects. 相似文献
110.
Data gathered from energy audits, phone surveys and smart meter readings are used to derive regression models of the electricity consumption of housing units in Oshawa (Ontario, Canada). The database used comprises 59 predictors, for 62 observations. To address the problem of multi-collinearities among the predictors and at the same time reduce the number of needed predictors, a methodology is developed based on the latent root regression technique of Hawkins [5]. Contrary to other variable selection techniques such as the stepwise method, the technique used in this paper allows an easy identification of alternative subsets. Using this technique, a reduction of 85% in the number of predictors is obtained, leaving only nine of them in the final subset. These nine variables are the number of occupants, the house status (owned or rented), the number of weeks of vacation per year, the type of fuel used in the pool heater, the type of fuel used in the heating system, the type of fuel used in the domestic hot water heater, the existence or not of an air conditioning system, the type of air conditioning system, and the number of air changes per hour at 50 Pa. A regression with these nine predictors leads to an R2 of 0.79, with an adjusted R2 of 0.75 and all regression coefficients statistically significant at the 95% confidence level. 相似文献