全文获取类型
收费全文 | 3091篇 |
免费 | 251篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 23篇 |
综合类 | 2篇 |
化学工业 | 660篇 |
金属工艺 | 47篇 |
机械仪表 | 65篇 |
建筑科学 | 103篇 |
矿业工程 | 5篇 |
能源动力 | 62篇 |
轻工业 | 654篇 |
水利工程 | 43篇 |
石油天然气 | 10篇 |
无线电 | 129篇 |
一般工业技术 | 480篇 |
冶金工业 | 731篇 |
原子能技术 | 1篇 |
自动化技术 | 329篇 |
出版年
2024年 | 8篇 |
2023年 | 26篇 |
2022年 | 35篇 |
2021年 | 76篇 |
2020年 | 65篇 |
2019年 | 76篇 |
2018年 | 124篇 |
2017年 | 129篇 |
2016年 | 140篇 |
2015年 | 116篇 |
2014年 | 108篇 |
2013年 | 236篇 |
2012年 | 201篇 |
2011年 | 227篇 |
2010年 | 154篇 |
2009年 | 131篇 |
2008年 | 111篇 |
2007年 | 150篇 |
2006年 | 69篇 |
2005年 | 63篇 |
2004年 | 66篇 |
2003年 | 68篇 |
2002年 | 72篇 |
2001年 | 44篇 |
2000年 | 33篇 |
1999年 | 45篇 |
1998年 | 275篇 |
1997年 | 162篇 |
1996年 | 96篇 |
1995年 | 51篇 |
1994年 | 33篇 |
1993年 | 37篇 |
1992年 | 10篇 |
1991年 | 15篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 1篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1976年 | 23篇 |
1973年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有3344条查询结果,搜索用时 0 毫秒
1.
2.
Rodríguez-Pérez Ángel Mariano Pérez-Calañas Cinta Pulido-Calvo Inmaculada 《Water Resources Management》2021,35(6):1977-1990
Water Resources Management - This paper aims to evaluate the possibility of using non-utilized hydraulic energy in urban water distribution systems. For this purpose, the viability and possible... 相似文献
3.
Lorena Rodríguez-López Myriam Rincón-Fontán Xanel Vecino Ana B. Moldes Jose M. Cruz 《Journal of surfactants and detergents》2020,23(1):79-90
Over the last few years, the global biosurfactant market has raised due to the increasing awareness among consumers, for the use of biological or bio-based products. Because of their composition, it can be speculated that these are more biocompatible and more biodegradable than their chemical homologous. However, at the moment, no studies exist in the literature about the biodegradability of biosurfactants. In this work, a biosurfactant contained in a crude extract, obtained from a corn wet-milling industry stream that ferments spontaneously in the presence of lactic acid bacteria, was subjected to a biodegradation study, without addition of external microbial biomass, under different conditions of temperature (5–45 °C), biodegradation time (15–55 days), and pH (5–7). For that, a Box–Behnken factorial design was applied, which allowed to predict the percentage of biodegradation for the biosurfactant contained in the crude extract, between the range of the independent variables selected in the study, obtaining biodegradation values between 3 and 80%. The percentage of biodegradation for the biosurfactant was calculated based on the increase in the surface tension of samples of the crude extract. Furthermore, it was also possible to predict the variation in t1/2 for the biosurfactant (time to achieve the 50% of biodegradation) under different conditions. 相似文献
4.
J Comas I Rodríguez-Roda M Poch K V Gernaey C Rosen U Jeppsson 《Water science and technology》2006,53(4-5):303-311
Wastewater treatment plant operators encounter complex operational problems related to the activated sludge process and usually respond to these by applying their own intuition and by taking advantage of what they have learnt from past experiences of similar problems. However, previous process experiences are not easy to integrate in numerical control, and new tools must be developed to enable re-use of plant operating experience. The aim of this paper is to investigate the usefulness of a case-based reasoning (CBR) approach to apply learning and re-use of knowledge gained during past incidents to confront actual complex problems through the IWA/COST Benchmark protocol. A case study shows that the proposed CBR system achieves a significant improvement of the benchmark plant performance when facing a high-flow event disturbance. 相似文献
5.
ML Martínez-Frías E Bermejo Sánchez E Rodríguez Pinilla A Villa 《Canadian Metallurgical Quarterly》1997,46(6):593-596
INTRODUCTION: Even though there are few epidemiological studies evaluating the birth weights of different groups of malformed babies with chromosomal abnormalities, it is widely known that infants with trisomy 18, and to a lesser degree those with trisomy 13 and other chromosomal alterations, have low birth weights. PATIENTS AND METHODS: In this study we present the analysis of the birth weights and gestational ages of a large sample of babies (23,155 malformed and a similar number of nonmalformed babies), separating the different groups of chromosomal anomalies and comparing the weight in the clinical groups of malformed infants. RESULTS: Most of the groups with chromosomal abnormalities present lower birth weights in comparison to the other groups. CONCLUSIONS: The results of our study support the conclusion that the relationship between chromosomal alterations and low birth weight is sufficiently important that such a low birth weight in children with minor or major anomalies should be considered as one more indication to perform chromosomal analysis. 相似文献
6.
Generation of Technology-Independent Retargetable Analog Blocks 总被引:1,自引:0,他引:1
R. Castro-López F. V. Fernández F. Medeiro A. Rodríguez-Vázquez 《Analog Integrated Circuits and Signal Processing》2002,33(2):157-170
This paper introduces a complete methodology for retargeting of analog cells to different sets of specifications. This methodology is technology-independent, thus allowing the migration, from one technology to another, of the circuit under retargeting. Careful integration of the device sizing and layout generation tasks via the incorporation of layout constraints during the sizing process allows to generate fully functional designs in a few minutes. The methodology is illustrated via the retargeting of a fully-differential Miller-compensated two-stage operational amplifier for a new set of specifications and two different technological processes.An erratum to this article can be found at 相似文献
7.
Vanesa Rodríguez-Amor Juan P. Fernández-Blázquez Antonio Bello Ernesto Pérez María L. Cerrada 《Polymer Bulletin》2008,60(1):89-96
Summary The effect of molecular weight on the uniaxial orientation process has been analyzed in two samples of thermotropic poly(diethylene
glycol p,p′-bibenzoate), evaluating the influence of that parameter on the type of orientation obtained. Several strain rates and deformation
temperatures have been tested in order to map out the conditions for obtaining the two different kinds of orientation. The
results show that in the lower molecular weight PDEB sample (Mw=31200) it is rather easy to get exclusively perpendicular “anomalous” orientation, with the molecular axes aligned transversely
to the stretching direction. However, it is extremely difficult to obtain 100% parallel “normal” orientation. On the contrary,
either type of orientation or a mixture of them can be easily developed for the higher molecular weight PDEB sample (Mw=102900). 相似文献
8.
Martín A. Rodríguez Ricardo M. Carranza Raúl B. Rebak 《Metallurgical and Materials Transactions A》2005,36(5):1179-1185
Alloy 22 (N06022) is the current candidate alloy used to fabricate the external wall of the high-level nuclear waste containers
for the Yucca Mountain repository. It was of interest to study and compare the general and localized corrosion susceptibility
of Alloy 22 in fluoride and chloride solutions at 90 °C. Standard electrochemical tests such as cyclic potentiodynamic polarization,
amperometry, and electrochemical impedance spectroscopy were used. Studied variables included the solution pH and the alloy
microstructure (thermal aging). Results show that Alloy 22 is highly resistant to general corrosion in all the solutions tested.
Thermal aging is not detrimental and even seems to be slightly beneficial for general corrosion at the higher solution pHs.
Pitting corrosion was never observed. Crevice corrosion was found only for high chloride-containing solutions after anodic
polarization. The presence of fluoride ions together with chloride ions seems to increase the susceptibility of Alloy 22 to
crevice corrosion compared to pure chloride solutions.
This article is based on a presentation made in the symposium “Effect of Processing on Materials Properties for Nuclear Waste
Disposition,” November 10–11, 2003, at the TMS Fall meeting in Chicago, Illinois, under the joint auspices of the TMS Corrosion
and Environmental Effects and Nuclear Materials Committees. 相似文献
9.
JA Carballido Rodríguez 《Canadian Metallurgical Quarterly》1997,21(7):641-643
A case of a large dentigerous cyst containing a canine tooth in the maxillary antrum is presented. This case is of interest due because of its extensiveness and the presence of a canine tooth in the roof of the maxillary sinus. In addition, this caused a right-sided epiphora. Enucleation of the cyst containing the ectopic tooth was made. 相似文献
10.