全文获取类型
收费全文 | 312篇 |
免费 | 37篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 91篇 |
金属工艺 | 5篇 |
机械仪表 | 4篇 |
建筑科学 | 18篇 |
矿业工程 | 1篇 |
能源动力 | 4篇 |
轻工业 | 48篇 |
石油天然气 | 1篇 |
无线电 | 28篇 |
一般工业技术 | 60篇 |
冶金工业 | 44篇 |
原子能技术 | 1篇 |
自动化技术 | 47篇 |
出版年
2023年 | 8篇 |
2022年 | 15篇 |
2021年 | 16篇 |
2020年 | 12篇 |
2019年 | 11篇 |
2018年 | 10篇 |
2017年 | 6篇 |
2016年 | 18篇 |
2015年 | 10篇 |
2014年 | 26篇 |
2013年 | 20篇 |
2012年 | 19篇 |
2011年 | 21篇 |
2010年 | 17篇 |
2009年 | 16篇 |
2008年 | 16篇 |
2007年 | 10篇 |
2006年 | 6篇 |
2005年 | 7篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1998年 | 21篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1976年 | 2篇 |
1960年 | 1篇 |
1941年 | 2篇 |
1940年 | 3篇 |
1939年 | 5篇 |
1938年 | 9篇 |
排序方式: 共有353条查询结果,搜索用时 15 毫秒
81.
Rainer Kümmerle Bastian Steder Christian Dornhege Alexander Kleiner Giorgio Grisetti Wolfram Burgard 《Autonomous Robots》2011,30(1):25-39
The problem of learning a map with a mobile robot has been intensively studied in the past and is usually referred to as the
simultaneous localization and mapping (SLAM) problem. However, most existing solutions to the SLAM problem learn the maps
from scratch and have no means for incorporating prior information. In this paper, we present a novel SLAM approach that achieves
global consistency by utilizing publicly accessible aerial photographs as prior information. It inserts correspondences found
between stereo and three-dimensional range data and the aerial images as constraints into a graph-based formulation of the
SLAM problem. We evaluate our algorithm based on large real-world datasets acquired even in mixed in- and outdoor environments
by comparing the global accuracy with state-of-the-art SLAM approaches and GPS. The experimental results demonstrate that
the maps acquired with our method show increased global consistency. 相似文献
82.
Occurrence of cotton herbicides and insecticides in playa lakes of the High Plains of West Texas 总被引:1,自引:0,他引:1
During the summer of 1997, water samples were collected and analyzed for pesticides from 32 playa lakes of the High Plains that receive drainage from both cotton and corn agriculture in West Texas. The major cotton herbicides detected in the water samples were diuron, fluometuron, metolachlor, norflurazon, and prometryn. Atrazine and propazine, corn and sorghum herbicides, were also routinely detected in samples from the playa lakes. Furthermore, the metabolites of all the herbicides studied were found in the playa lake samples. In some cases, the concentration of metabolites was equal to or exceeded the concentration of the parent compound. The types of metabolites detected suggested that the parent compounds had been transported to and had undergone degradation in the playa lakes. The types of metabolites and the ratio of metabolites to parent compounds may be useful in indicating the time that the herbicides were transported to the playa lakes. The median concentration of total herbicides was 7.2 microg/l, with the largest total concentrations exceeding 30 microg/l. Organophosphate insecticides were detected in only one water sample. Further work will improve the understanding of the fate of these compounds in the playa lake area. 相似文献
83.
A study was undertaken to investigate the effects of the EP additives during tribological tests using a CBN tool against steel. Ester oil with and without sulfur additive were used as lubricants in a tribometer. Tribochemical interactions between the S additive and steel have been investigated under boundary lubrication conditions by SEM and EDX analysis. The relative abundance of different elements on the surface of the CBN tools, which are present in the workpiece material such as Fe (iron) and Cr (chromium), suggests that adhesion occurred when the ester oil without sulfur additive was tested. Tribochemical interactions between the additive and the steel could be observed when using the ester oil containing the sulfur additive. These interactions contribute to the formation of a uniform layer on the CBN tool. This layer is composed by S (sulfur), Fe, and O (oxygen). The presence of these elements indicate that FeO (iron oxide) and FeS (iron sulfide) were formed. 相似文献
84.
85.
86.
87.
Johannes Schffer Bastian Zehner Wolfgang Korth Mirza Cokoja Andreas Jess 《化学工程与技术》2019,42(1):232-240
The biphasic catalytic epoxidation of cyclooctene using the ionic liquid (IL) 1,2‐dimethyl‐3‐octyl‐imidazolium perrhenate ([OMMIM]ReO4) as micellar catalyst and H2O2 as oxidant was investigated. Kinetic experiments were carried out in the intrinsic kinetic regime as proved by variation of stirring rate and temperature. Variation of catalyst concentration allowed for determination of the critical micellar concentration (CMC) of the catalytic IL. The effect of substrate concentrations on the reaction rate was also assessed. Based on the experiments, a kinetic model adapted from enzyme catalysis was proposed to account for the micellar reaction environment. The model takes into account the onset of micelle formation at the CMC. The application of the kinetic model illustrated the good agreement with the experimental data. The model will be applied to other micellar epoxidation reactions and for the design of an appropriate reaction setup in the future. 相似文献
88.
89.
M. Mert Ankaral? Shahin Sefati Manu S. Madhav Andrew Long Amy J. Bastian Noah J. Cowan 《Journal of the Royal Society Interface》2015,12(108)
Many biological phenomena such as locomotion, circadian cycles and breathing are rhythmic in nature and can be modelled as rhythmic dynamical systems. Dynamical systems modelling often involves neglecting certain characteristics of a physical system as a modelling convenience. For example, human locomotion is frequently treated as symmetric about the sagittal plane. In this work, we test this assumption by examining human walking dynamics around the steady state (limit-cycle). Here, we adapt statistical cross-validation in order to examine whether there are statistically significant asymmetries and, even if so, test the consequences of assuming bilateral symmetry anyway. Indeed, we identify significant asymmetries in the dynamics of human walking, but nevertheless show that ignoring these asymmetries results in a more consistent and predictive model. In general, neglecting evident characteristics of a system can be more than a modelling convenience—it can produce a better model. 相似文献
90.
Models have been developed for binary, incompatible polymer blends that can be used to estimate the morphology development that takes place in drops of the second component that are dispersely embedded in the matrix. The calculations are based on the results of flow simulations using the boundary element (BEM) and finite element (FEM) methods and, more particularly, on an analysis of the stresses that act on fluid particles over their trajectories as a function of the residence time. The models formulated are converted into algorithms, which can then be implemented in the SIGMA simulation software for designing and simulating the process behavior in tightly intermeshing co‐rotating twin‐screw extruders. In this way, it is possible to estimate the morphology development that takes place in incompatible polymer systems by describing the mean drop size and the drop size distribution as a function of the material properties, the geometry of the barrel and the screw, and the process parameters. 相似文献