全文获取类型
收费全文 | 1339篇 |
免费 | 36篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 18篇 |
化学工业 | 280篇 |
金属工艺 | 42篇 |
机械仪表 | 40篇 |
建筑科学 | 14篇 |
矿业工程 | 2篇 |
能源动力 | 78篇 |
轻工业 | 67篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 207篇 |
一般工业技术 | 289篇 |
冶金工业 | 168篇 |
原子能技术 | 10篇 |
自动化技术 | 159篇 |
出版年
2023年 | 12篇 |
2022年 | 29篇 |
2021年 | 30篇 |
2020年 | 26篇 |
2019年 | 30篇 |
2018年 | 38篇 |
2017年 | 40篇 |
2016年 | 33篇 |
2015年 | 29篇 |
2014年 | 22篇 |
2013年 | 71篇 |
2012年 | 46篇 |
2011年 | 63篇 |
2010年 | 43篇 |
2009年 | 52篇 |
2008年 | 53篇 |
2007年 | 52篇 |
2006年 | 44篇 |
2005年 | 43篇 |
2004年 | 32篇 |
2003年 | 20篇 |
2002年 | 38篇 |
2001年 | 26篇 |
2000年 | 19篇 |
1999年 | 17篇 |
1998年 | 54篇 |
1997年 | 45篇 |
1996年 | 32篇 |
1995年 | 20篇 |
1994年 | 23篇 |
1993年 | 24篇 |
1992年 | 20篇 |
1991年 | 14篇 |
1989年 | 16篇 |
1988年 | 14篇 |
1986年 | 13篇 |
1985年 | 16篇 |
1984年 | 17篇 |
1983年 | 12篇 |
1982年 | 9篇 |
1980年 | 8篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1977年 | 13篇 |
1976年 | 15篇 |
1975年 | 15篇 |
1974年 | 10篇 |
1973年 | 9篇 |
1972年 | 6篇 |
1971年 | 9篇 |
排序方式: 共有1377条查询结果,搜索用时 15 毫秒
1.
2.
A mechanism of soldering of an aluminum alloy die casting to a steel die is proposed. A soldering critical temperature is
postulated, at which iron begins to react with aluminum to form an aluminum-rich liquid phase and solid intermetallic compounds.
The liquid joins the die with the casting upon solidification. The critical temperature is determined by the elements in both
the casting alloy and the die material and is equal to the solidus temperature of the resulting alloy. The critical temperature
is used to predict the onset of die soldering, and the local liquid fraction is related to the soldering tendency. Experiments
have been carried out to validate the concept and to determine the critical temperature for die soldering in an iron-aluminum
system. Thermodynamic calculations are used to determine the critical temperature and soldering tendency for the cases of
pure aluminum and a 380 alloy in a steel mold. Factors affecting the soldering tendency are discussed, and methods for reducing
die soldering are suggested. 相似文献
3.
V. Vassilev S. Thijs P. L. Segura P. Wambacq P. Leroux G. Groeseneken M. I. Natarajan H. E. Maes M. Steyaert 《Microelectronics Reliability》2005,45(2):255-268
This paper describes an approach to design ESD protection for integrated low noise amplifier (LNA) circuits used in narrowband transceiver front-ends. The RF constraints on the implementation of ESD protection devices are relaxed by co-designing the RF and the ESD blocks, considering them as one single circuit to optimise. The method is applied for the design of 0.25 μm CMOS LNA. Circuit protection levels higher than 3 kV HBM stress are achieved using conventional highly capacitive ggNMOS snapback devices. The methodology can be extended to other RF-CMOS circuits requiring ESD protection by merging the ESD devices in the functionality of the corresponding matching blocks. 相似文献
4.
Becker-Gomez A. Lakshmi Viswanathan T. Viswanathan T.R. 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2008,55(7):609-613
5.
OBJECTIVE: To determine the characteristics and long-term outcome of radiation-induced thyroid cancer in children. DESIGN: Retrospective review of a cohort of 4296 irradiated patients who received childhood radiation treatment to the head and neck area at the same hospital. PATIENTS: Forty-one children who were younger than 20 years when thyroid cancer developed in them and 77 adults in whom thyroid cancer developed. All 118 cases were diagnosed before 1974 and were followed up for a median of 19.4 years. RESULTS: Children presented with clinically palpable lymph nodes more often than adults (30.7% vs 15.1%, P = .05) and had more recurrences (39% vs 16%, P = .05). Despite these frequent recurrences, only one patient (an adult) died of thyroid cancer. Seventy percent of the recurrences occurred during the first 10 years of follow-up, but recurrences continued after 20 years. The adults had previously identified factors that predicted the risk of recurrences, but none could be identified in the children. CONCLUSION: The presentation and relatively good outcome of radiation-induced thyroid cancer in children is similar to that in nonirradiated children. Frequent and late recurrences call for lifelong follow-up. 相似文献
6.
Hongxuan Zhang Venkatesha S. Minahan R. Sherman D. Oweis Y. Natarajan A. Thakor N.V. 《IEEE engineering in medicine and biology magazine》2006,25(4):39-45
Intraoperative neurological monitoring (INM) is the evaluation of the nervous system within the operating room (OR) environment. In this paper, the INM system is tested in a clinical setting in comparison with conventional somatosensory evoked potential (SEP) monitoring. The study results demonstrate the capability of the INM system in extracting clearer and more stable SEP signals. The high SNR of SEP signals collected in various clinical environments, including the OR, makes the INM system a robust platform for continuous monitoring. While the current use of EP monitoring is limited to intermittent analysis by a highly trained clinical neurophysiologist, the authors believe in changing this paradigm by developing continuous monitoring systems, such as the INM system, capable of automated quantitative EP analysis. This noninvasive monitoring modality will allow for a wider range of use in clinical practice. Based on volunteer and clinical patient studies, the INM monitoring system demonstrates much greater reliability and accuracy via the artifact rejection and denoising strategies. It provides more strategic filtering options for different situations under which the clinical SEP response signal could be greatly contaminated and distorted. Furthermore, the INM system offers a promising approach to signal extraction in real-time monitoring during SEP research. 相似文献
7.
S. Kar T. Searles E. Lee G. B. Viswanathan H. L. Fraser J. Tiley R. Banerjee 《Metallurgical and Materials Transactions A》2006,37(3):559-566
The development of a set of computational tools that permit microstructurally based predictions for the tensile properties
of commercially important titanium alloys, such as Ti-6Al-4V, is a valuable step toward the accelerated maturation of materials.
This paper will discuss the development of neural network models based on a Bayesian framework to predict the yield and ultimate
tensile strengths of Ti-6Al-4V at room temperature. The development of such rules-based model requires the population of extensive
databases, which in the present case are microstructurally based. The steps involved in database development include producing
controlled variations of the microstructure using novel approaches to heat treatments, the use of standardized stereology
protocols to characterize and quantify microstructural features rapidly, and mechanical testing of the heat-treated specimens.
These databases have been used to train and test neural network models for prediction of tensile properties. In addition,
these models have been used to identify the influence of individual microstructural features on the tensile properties, consequently
guiding the efforts toward development of more robust mechanistically based models. Based on the neural network model, it
is possible to investigate the influence of individual microstructural features on the tensile properties, and in certain
cases these dependencies can point toward unrecognized phenomena. For example, the apparently unexpected trend of increase
in tensile strength with increasing prior β-grain size has led to the determination of the pronounced role of the basketweave microstructure in strengthening these alloys,
especially in case of larger prior β grains.
This article is based on a presentation made in the symposium “Computational Aspects of Mechanical Properties of Materials,”
which occurred at the 2005 TMS Annual Meeting, February 13–17, 2005, in San Francisco, CA, under the auspices of the MPMD-Computational
Materials Science & Engineering (Jt. ASM-MSCTS) Committee. 相似文献
8.
9.
The behavior and suitability of cold-formed lipped angle members for X-bracing with redundant have been studied. For the purpose, two full-scale panel tests were carried out. The first panel was designed so that the compression member would fail by buckling in flexural mode and the second panel in flexural-torsional mode. The members were designed using ASCE Manual No. 52. Theoretical aspects of least radius of gyration and buckling behavior of this bracing system have been discussed. The investigation on first panel, revealed that the member would buckle only in the flexural-torsional mode although flexural buckling would govern the design. The second panel test result showed that, the buckling mode and strength of the system for lipped angle sections can be predicted reasonably well. 相似文献
10.