全文获取类型
收费全文 | 2560篇 |
免费 | 190篇 |
国内免费 | 14篇 |
专业分类
电工技术 | 49篇 |
综合类 | 17篇 |
化学工业 | 661篇 |
金属工艺 | 62篇 |
机械仪表 | 39篇 |
建筑科学 | 126篇 |
矿业工程 | 6篇 |
能源动力 | 132篇 |
轻工业 | 101篇 |
水利工程 | 12篇 |
石油天然气 | 7篇 |
无线电 | 252篇 |
一般工业技术 | 571篇 |
冶金工业 | 111篇 |
原子能技术 | 5篇 |
自动化技术 | 613篇 |
出版年
2024年 | 6篇 |
2023年 | 60篇 |
2022年 | 123篇 |
2021年 | 159篇 |
2020年 | 107篇 |
2019年 | 105篇 |
2018年 | 109篇 |
2017年 | 121篇 |
2016年 | 131篇 |
2015年 | 100篇 |
2014年 | 159篇 |
2013年 | 188篇 |
2012年 | 209篇 |
2011年 | 220篇 |
2010年 | 134篇 |
2009年 | 140篇 |
2008年 | 121篇 |
2007年 | 97篇 |
2006年 | 81篇 |
2005年 | 41篇 |
2004年 | 46篇 |
2003年 | 41篇 |
2002年 | 32篇 |
2001年 | 27篇 |
2000年 | 22篇 |
1999年 | 22篇 |
1998年 | 29篇 |
1997年 | 17篇 |
1996年 | 7篇 |
1995年 | 14篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1992年 | 10篇 |
1991年 | 9篇 |
1990年 | 14篇 |
1989年 | 4篇 |
1987年 | 3篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1981年 | 4篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1971年 | 2篇 |
排序方式: 共有2764条查询结果,搜索用时 15 毫秒
61.
In continuous steel or concrete structures with surface-mounted fibre reinforced polymer (FRP) plates as flexural reinforcement, self-equilibrating moments can influence the loads at first yield and at failure, the latter due to potential buckling of the FRP plate or to end-peel both on account of offsets between points of contraflexure and the nearby FRP curtailments. In this paper, expressions are derived for the total (including self-equilibrating) moments along 2-span continuous structures with differential settlement. The expressions show how moments depend on support-to-member stiffness ratios and on distributions of section stiffness for service and ultimate limit states. Thus, the analysis is generic, applicable to FRP-reinforced steel and concrete structures. This analysis is verified via test data (including observation of end-peel in FRP compression curtailment zones offset from nearby contraflexure) and is used to construct 3D plots that facilitate identification of stiffness ratios which lead to significant self-equilibrating moments and contraflexure offset effects. Use of the plots to assess influences of differential settlement on laboratory test specimens is discussed. The analysis is shown to lead to an unprecedented result, namely that a unique point of load application exists for which changes to the stiffness layout have no impact on the moment distribution. 相似文献
62.
63.
Typical feed gas mixtures used in technological and other plasmas may give rise to reaction networks involving several hundred reactions. Such chemistries are often too large to be used in full reactor simulations and it is therefore desirable to construct reduced chemistry networks which mimic as closely as possible the behavior of the full chemistry but employ far fewer individual reactions and species. Constructed chemistries are available from the Quantemol database (QDB) and two approaches to constructing reduced chemistry from these chemistries based on (a) physical intuition and (b) sensitivity analysis of dominant reaction pathways, are explored. In doing this it is necessary to consider different pressure and power regimes. Reduced chemistry sets are presented for CF4 /O2/N2/H2, for which 396 reactions and 52 species are reduced to 71 reactions and 26 species, and for pure O2, for which 45 reactions and 10 species are reduced to 34 reactions. 相似文献
64.
Neumann Sebastian Asad Amjad Kasper Tom Schwarze Rüdiger 《Metallurgical and Materials Transactions B》2019,50(5):2334-2342
Metallurgical and Materials Transactions B - In the paper, two different cleaning strategies for nonmetallic inclusions in steel melts, active filtration and reactive cleaning, are examined in a... 相似文献
65.
Xiao Junbing Yan Hongjie Liu Liu Möller Felix Hu Zhiwen Unger Sebastian 《Metallurgical and Materials Transactions B》2019,50(6):3002-3011
Metallurgical and Materials Transactions B - Spout height is a widely used parameter to quantitatively analyze the performance of the submerged gas injection in industrial applications. However,... 相似文献
66.
Three‐dimensional modeling of porosity development during the gasification of a char particle 下载免费PDF全文
Kay Wittig Petr A. Nikrityuk Sebastian Schulze Andreas Richter 《American Institute of Chemical Engineers》2017,63(5):1638-1647
This work is devoted to the three‐dimensional, direct modeling of porosity and specific surface development during the gasification of a char particle. The model was developed for heterogeneous reactions occurring inside a char particle in a kinetically controlled regime. The main goal of this work is to analyze the impact of different pore size distributions on the particle carbon conversion rate. In particular, it is shown that under certain conditions the outer particle surface can influence the specific surface area. In this context the possible adaptation of the parameter ψ from the random pore model (RPM) developed by Bhatia and Perlmutter is explained. The results of simulations are compared against the RPM and discussed. Additionally, based on the results of simulations, the physics behind several input parameters used by the RPM are explored. Finally, the possible fragmentation of a chemically reacting char particle during its gasification in dependence of instantaneous porosity was investigated numerically. It was shown that the earliest fragmentation occurs at a carbon conversion of about 0.5–0.6 due to the disaggregation of the pore walls. The results are discussed and compared implicitly with data published in the literature. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1638–1647, 2017 相似文献
67.
Ignacio Contreras Andrade ;Jonathan Parra Santiago ;Jose Ricardo Sodre ;Joseph Sebastian Pathiyamattom ;Carlos Alberto Guerrero-Fajardo 《化学与化工:英文版》2014,(7):717-726
Currently, biodiesel is presented as one of the best alternatives for gradually replacing the use of fossil fuels, but it has some factors that make it economically impractical if it does not have a government support. For this reason, research efforts focused on this area have been responsible for optimizing the process of biodiesel production by different catalytic routes to achieve greater efficiency at a lower cost. In this case, the biggest problem has been the high cost generated by an investigation, which in many occasions is the main factor to decide if an investigation could be carried out. Trying to reduce these costs, in the current study, we are using a technique of glycerol quantification by volumetric methods and comparing obtained results with the chromatographic method, which is conventionally used and comparatively much more expensive. Biodiesel employee was obtained by an enzymatic catalysis process varying one of three process variables:oil:alcohol molar ratio, temperature and proportion of catalyst. The numerical differences obtained between the two quantification methods generated relative errors lower than 10%, resulting in some occasions lower than 1%. By gas chromatography analysis the best yield was obtained at the same conditions of the volumetric method, a temperature of 45 ℃, an oil:alcohol ratio 1:4 and 8 wt.% of catalyst, but a yield of 95.5% and 97.1%, respectively. Due to the high precision of gas chromatography, this method is used to carry out a surface response analysis obtaining as ideal operating conditions a temperature of 43.5 ℃, 8.9 wt.%. of catalyst and an oil:alcohol ratio 1:4. 相似文献
68.
Priti Tagde Agnieszka Najda Kalpana Nagpal Giriraj T. Kulkarni Muddaser Shah Obaid Ullah Sebastian Balant Md. Habibur Rahman 《International journal of molecular sciences》2022,23(5)
Breast cancer is one of the most common types of cancer among women globally. It is caused by mutations in the estrogen/progesterone receptors and conventional treatment methods are commonly utilized. About 70–80 percent of individuals with the early-stage non-metastatic disease may be cured. Conventional treatment is far less than the optimal ratio, as demonstrated through the high mortality rate of women with this cancer. However, conventional treatment methods like surgery, radiotherapy, and chemotherapy are not as effective as expected and lead to concerns about low bioavailability, low cellular uptake, emerging resistance, and adverse toxicities. A nanomedicine-based approach is a promising alternative for breast cancer treatment. The present era is witnessing rapid advancements in nanomedicine as a platform for investigating novel therapeutic applications and modern intelligent healthcare management strategies. This paper focuses on nanomedicine-based therapeutic interventions that are becoming more widely accepted for improving treatment effectiveness and reducing undesired side effects in breast cancer patients. By evaluating the state-of-the-art tools and taking the challenges involved into consideration, various aspects of the proposed nano-enabled therapeutic approaches have been discussed in this review. 相似文献
69.
Adeel Nasir Peter Rolf Richter Aude Le Bail Viktor Daiker Julia Stoltze Binod Prasad Sebastian Michael Strauch Michael Lebert 《International journal of molecular sciences》2022,23(5)
Euglena gracilis is a photosynthetic flagellate. To acquire a suitable position in its surrounding aquatic environment, it exploits light and gravity primarily as environmental cues. Several physiological studies have indicated a fine-tuned relationship between gravity sensing (gravitaxis) and light sensing in E. gracilis. However, the underlying molecular mechanism is largely unknown. The photoreceptor photoactivated adenylyl cyclase (PAC) has been studied for over a decade. Nevertheless, no direct/indirect interaction partner (upstream/downstream) has been reported for PAC. It has been shown that a specific protein, kinase A (PKA), showed to be involved in phototaxis and gravitaxis. The current study reports the localization of the specific PKA and its relationship with PAC. 相似文献
70.