全文获取类型
收费全文 | 1168篇 |
免费 | 121篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 12篇 |
综合类 | 2篇 |
化学工业 | 318篇 |
金属工艺 | 8篇 |
机械仪表 | 21篇 |
建筑科学 | 66篇 |
矿业工程 | 1篇 |
能源动力 | 32篇 |
轻工业 | 260篇 |
水利工程 | 9篇 |
石油天然气 | 2篇 |
无线电 | 46篇 |
一般工业技术 | 197篇 |
冶金工业 | 38篇 |
原子能技术 | 1篇 |
自动化技术 | 277篇 |
出版年
2024年 | 5篇 |
2023年 | 12篇 |
2022年 | 22篇 |
2021年 | 49篇 |
2020年 | 43篇 |
2019年 | 38篇 |
2018年 | 66篇 |
2017年 | 56篇 |
2016年 | 63篇 |
2015年 | 47篇 |
2014年 | 73篇 |
2013年 | 123篇 |
2012年 | 104篇 |
2011年 | 100篇 |
2010年 | 63篇 |
2009年 | 71篇 |
2008年 | 58篇 |
2007年 | 75篇 |
2006年 | 42篇 |
2005年 | 37篇 |
2004年 | 35篇 |
2003年 | 40篇 |
2002年 | 15篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 2篇 |
排序方式: 共有1290条查询结果,搜索用时 31 毫秒
141.
Victoria Fernández Azahara Díaz Álvaro Blanco Jesús Val 《Journal of the science of food and agriculture》2009,89(13):2323-2330
BACKGROUND: A strategy to supply Ca directly to fruits as a tool for improving peach quality has been devised and tested under field conditions. Since peaches in the area of study (Calanda, Spain) are routinely bagged shortly after thinning, a method based on the application of Ca gels to the fruit surface was introduced. The effect of surface treatments was assessed in terms of quality, nutrient balance and surface deposition. RESULTS: Application of Ca‐containing formulations increased mesocarp and exocarp Ca concentrations, providing evidence for the penetration of Ca through the peach skin. Surface Ca treatments had a particular mode of deposition and in some instances improved the shelf life of fruits without affecting their quality. CONCLUSION: Surface treatment with Ca‐containing gels appears to be a viable approach to increase fruit Ca, quality and storability of bagged peach cultivars and should be optimised in future studies. Copyright © 2009 Society of Chemical Industry 相似文献
142.
A System Dynamics Model to Evaluate Temporary Water Transfers in the Mexican Conchos Basin 总被引:1,自引:1,他引:0
The flows of the Rio Conchos are of vital economic importance not only to the agricultural sector in the Mexican side of the
Rio Grande basin but also for meeting Mexico’s obligation to deliver water to the United States. During the previous decade,
a severe drought dramatically decreased the basin’s runoff, generating serious economic, social, and political problems in
both countries. A System Dynamics (SD) model designed to serve as a decision-support system (DSS) for water managers has been
created. This DSS is a lumped semi-distributed model operating on a monthly basis. This DSS incorporates the most important
elements of the Conchos basin’s water resources system: main rivers, irrigation distribution canals, reservoirs, aquifer,
and the three Irrigation Districts. The DSS simulates different short and long term scenarios combining inside and outside
Irrigation Districts (IDs). Also, different short scenarios are implemented to investigate the benefits of water transfer
from México to the United States. This study has prompted awareness with regards to the degree of complexity and uncertainty
of the water right allocation process to different economic variables such as crop yield, production costs, crop prices, subsidies,
and water distribution efficiencies. 相似文献
143.
Jesús Agudelo José Antonio Suárez Agustín Olano María Jesús Callejo María Beatriz Colomo 《European Food Research and Technology》1994,199(1):26-28
Gas chromatography was used to study the polysaccharides present in samples that exhibited significant microbially induced viscosity values. Alterations in the media considered were related to the percentage glucose content and the total polysaccharide content. 相似文献
144.
The effect of high hydrostatic pressure on turbidity of skim milk was measured in situ together with casein micelle size distribution. High pressure (HP) treatment reduced the turbidity of milk with a stronger pressure dependency between 50 and 300 MPa when the temperature was decreased from 20 to 5 °C, while at 30 °C (50–150 MPa) turbidity exceeded that of untreated milk. At 250 and 300 MPa turbidity decreased extremely. During pressurization of milk at 250 and 300 MPa, the turbidity initially decreased, but treatments longer than 10 min increased the turbidity progressively, indicating that re-association followed dissociation of casein micelles. Especially at 40 °C and at 250 and 300 MPa, the turbidity increased beyond untreated milk. Dynamic light scattering was used to investigate casein micelle sizes in milk immediately after long time (up to 4 h) pressurization at 250 and 300 MPa and casein micelle size distributions were bimodal with micelle sizes markedly smaller and markedly larger than those of untreated milk. Pressure modified casein micelles present after treatment of milk at 250 and 300 MPa were concluded to be highly unstable, since the larger micelles induced by pressure showed marked changes toward smaller particle sizes in milk left at ambient pressure. 相似文献
145.
Diñeiro Y Menéndez MI Blanco-López MC Lobo-Castañón MJ Miranda-Ordieres AJ Tuñón-Blanco P 《Analytical chemistry》2005,77(20):6741-6746
A methodology based on density functional theory calculations for the design of molecularly imprinted polymers (MIPs) is described. The method allows the rational choice of the most suitable monomer and polymerization solvent among a set of chemicals traditionally used in MIP formulations for the molecular imprinting of a given template. It is based on the comparison of the stabilization energies of the prepolymerization adducts between the template and different functional monomers. The effect of the polymerization solvent is included using the polarizable continuum model. A voltammetric sensor for homovanillic acid was constructed using different MIPs as recognition element, confirming that the solvent (toluene) and functional monomer (methacrylic acid) selected according to the theoretical predictions lead to the most efficient molecular recognition sensing phase. With the voltammetric sensor prepared using the MIP designed according to the theoretical predictions, a linear response for concentrations of homovanillic acid between 5 x 10(-8) and 1 x 10(-5) M can be obtained. The limit of detection is 7 x 10(-9) M. The selectivity obtained for homovanillic acid over other structurally related compounds buttresses the validity of this strategy of design. 相似文献
146.
Jesús?García?HerreroEmail author Antonio?Berlanga José?M.?Molina José?R.?Casar 《Applied Intelligence》2005,22(3):183-206
Simulation and decision support tools can help airport ground controllers to improve surface operations and safety, leading to enhancements in the process of traffic flow management. In this paper, two planning approaches for automatically finding the best routes and sequences for demanded operations are proposed and analyzed. These approaches are integrated into a general decision support system architecture. The problem addressed is the global management of departure operations, moving aircraft along airport taxiways between gate positions and runways. Two global optimization approaches have been developed together with a suitable problem representation: a modified time-space flow algorithm and a genetic algorithm, both aimed at minimizing the total ground delay. The capability and performance of these planning techniques have been illustrated on simulated samples of ground operations at Madrid Barajas International Airport.This work was funded by CICYT (TIC2002-04491-C02-02) and CAM (07T/0034/2003 1) 相似文献
147.
de-Los-Santos-Alvarez N de-Los-Santos-Alvarez P Lobo-Castañón MJ Miranda-Ordieres AJ Tuñón-Blanco P 《Analytical chemistry》2005,77(13):4286-4289
The generation of a new electrocatalytic system for NADH after oxidizing flavin adenine dinucleotide (FAD) is shown. The oxidation is performed in alkaline medium until +1.4 V (Ag/AgCl) at graphite electrodes. The catalytic activity is ascribed to the electrooxidized moiety of FAD and not to quinone surface groups. A comparison between this catalyst and that attributed to poly(FAD) (Karyakin, A. A.; Ivanova Y. N.; Revunova, K. V.; Karyakina, E. E. Anal. Chem. 2004, 76, 2004-2009.) is presented. It is concluded that the surface quinone groups generated during the strong anodization of the electrode in acidic medium at 2-2.5 V and not the poly(FAD) are responsible for the catalytic activity described in the above mentioned work. 相似文献
148.
We describe a novel algorithm for two-dimensional phase unwrapping. The technique combines the principles of agglomerative clustering and use of heuristics to construct a discontinuous quality-guided path. Unlike other quality-guided algorithms, which establish the path at the start of the unwrapping process, our technique constructs the path as the unwrapping process evolves. This makes the technique less prone to error propagation, although it presents higher execution times than other existing algorithms. The algorithm reacts satisfactorily to random noise and breaks in the phase distribution. A variation of the algorithm is also presented that considerably reduces the execution time without affecting the results significantly. 相似文献
149.
150.
This paper presents an alternative method to estimate somatic cell count (SCC) in cows' milk. SCC is an important indicator in the detection of inflammatory reactions within the udder in cows and Direct Optical Microscopy (DOM) is the present reference method for SCC but, owing to its dependence on human operators, it is extremely costly, time-consuming and potentially subjective. The industrial method of choice is Epifluorescence (EF), which has the potential for impressive throughput and acceptable precision, but requires huge inversions and handling of highly toxic reactives and waste. In this paper, an advantageous method that involves application of a low-cost Video Microscopy (VM) system is analysed and discussed, including a comparison between DOM and VM, and an example of application of both methods to evaluate EF counts. We conclude that VM is sufficiently precise and very cheap to implement and operate. 相似文献