全文获取类型
收费全文 | 981篇 |
免费 | 72篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 11篇 |
综合类 | 1篇 |
化学工业 | 204篇 |
金属工艺 | 14篇 |
机械仪表 | 69篇 |
建筑科学 | 21篇 |
矿业工程 | 2篇 |
能源动力 | 35篇 |
轻工业 | 96篇 |
水利工程 | 5篇 |
石油天然气 | 2篇 |
无线电 | 183篇 |
一般工业技术 | 201篇 |
冶金工业 | 79篇 |
原子能技术 | 5篇 |
自动化技术 | 131篇 |
出版年
2024年 | 4篇 |
2023年 | 12篇 |
2022年 | 26篇 |
2021年 | 45篇 |
2020年 | 38篇 |
2019年 | 39篇 |
2018年 | 52篇 |
2017年 | 48篇 |
2016年 | 42篇 |
2015年 | 30篇 |
2014年 | 28篇 |
2013年 | 63篇 |
2012年 | 52篇 |
2011年 | 91篇 |
2010年 | 41篇 |
2009年 | 55篇 |
2008年 | 53篇 |
2007年 | 36篇 |
2006年 | 36篇 |
2005年 | 37篇 |
2004年 | 28篇 |
2003年 | 22篇 |
2002年 | 20篇 |
2001年 | 8篇 |
2000年 | 17篇 |
1999年 | 17篇 |
1998年 | 22篇 |
1997年 | 12篇 |
1996年 | 17篇 |
1995年 | 17篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 8篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1976年 | 2篇 |
1972年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有1059条查询结果,搜索用时 15 毫秒
101.
Three newly found vibrational levels at energies Te(v) = 45127.88(3), 51900.40(4), and 52604.95(3) cm-1 allow the first application of resonance-enhanced multiphoton ionization for detecting the SO radical in its low-energy singlet states, a1Delta and b1Sigma+. The analysis of the spectra is based on the observation of 10 rotationally resolved bands starting from a1Delta v = 0, 6 ellipsis 11 and b1Sigma+ v = 8, covering a typical range of J = 5 ellipsis 40 or 50. Population of these SO singlet states has been achieved by two-photon dissociation of SO2 in a molecular beam environment, applying wavelengths in the 248 to 291 nm range. This paper presents an analysis of the rotational, vibrational, and electronic properties of the new levels. Reviewing earlier works on the singlet states of SO, a revised term energy scheme is provided which connects the singlet and triplet systems of the molecule. Copyright 1998 Academic Press. 相似文献
102.
We present a holistic approach to estimation that uses rough sets theory to determine a similarity template and then compute a runtime estimate using identified similar applications. We tested the technique in two real-life data-intensive applications: data mining and high-performance computing. 相似文献
103.
Wong Kin Fai Ellick; Yik Michelle; Kwong Jessica Y. Y. 《Canadian Metallurgical Quarterly》2006,91(2):282
Despite the importance of understanding the emotional aspects of organizational decision making, prior research has paid scant attention to the role of emotion in escalation of commitment. This article attempts to fill this gap by examining the relationship between negative affect and escalation of commitment. Results showed that regardless of whether negative affect was measured as a dispositional trait (Neuroticism) in Studies 1 and 2 or as a transient mood state in Study 3, it was negatively correlated with escalation tendency when one was personally responsible for a prior decision. This pattern of results is consistent with the predictions derived from the coping perspective, suggesting that people seek to escape from the unpleasant emotions that are associated with escalation situations. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
104.
Simultaneous determination of phosphate and silicate in waste water by sequential injection analysis
A sequential injection analysis system for the simultaneous determination of phosphate and silicate in waste water is proposed. The method is based on the formation of yellow vanadomolybdophosphate and molybdosilicate, respectively, in addition to the use of large sample volumes. The mutual interference between both analytes was eliminated by selection of the appropriate acidity and by sample segmentation with oxalic acid. The calibration graph for phosphate and silicate is linear up to 12 mg l-1 P and 30 mg l-1 Si, respectively. The detection limits are 0.2 mg l-1 P and 0.9 mg l-1 Si. The method provides a throughput of 23 samples h-1 with a relative standard deviation < 1.4% for phosphate and < 4% for silicate. The method was found to be suitable for the determination of these species in waste water samples. 相似文献
105.
106.
Seon Ah Roh Soon Hwa Jung Sang Mun Jeong Sang Done Kim 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2003,78(10):1104-1109
The selective catalytic reduction (SCR) of NOx by urea as a reducing agent was carried out over fresh and sulfated CuO/γ‐Al2O3 catalysts in a fluidized‐bed reactor. The optimum temperature ranges for NO reduction on the fresh and sulfated CuO/γ‐Al2O3 catalysts were 300–350 °C and 400–450 °C, respectively. NO reduction with the sulfated CuO/γ‐Al2O3 catalyst was somewhat higher than that with the fresh CuO/γ‐Al2O3 catalyst. N2O formation increased with increasing reaction temperature. Ammonia (NH3) slip increased with increasing gas velocity and decreased with increasing reaction temperature. Copyright © 2003 Society of Chemical Industry 相似文献
107.
J Aparicio A Oltra C Llorca J Montalar C Herranz J Gómez-Codina M Pastor B Munárriz 《Canadian Metallurgical Quarterly》1996,(10):1739-1743
With the availability of new, broad-spectrum antibiotics, initial therapy with a single agent has become an alternative to classic combinations in the management of febrile, neutropenic cancer patients. The aims of this study were to compare the efficacy of ceftazidime and imipenem as empirical monotherapy of febrile episodes in neutropenic patients, and to examine the frequency with which second-line antibiotics (amikacin, vancomycin, or both) were required. A prospective clinical trial was carried out in a single centre. Eligible patients with solid tumours or lymphoma were randomised to receive monotherapy with ceftazidime or imipenem. In the event of no response, amikacin and/or vancomycin were added in 48-72 h intervals (sequentially, or according to clinical or microbiological data). Efficacy was evaluable for 111 assessable episodes. Median neutrophil count at entry was 100 cells/microliters and median duration of neutropenia was 4 days. Febrile episodes were classified as microbiologically (34%) or clinically documented (42%), and fever of unknown origin (24%). Gram-negative infections (57%) predominated over gram-positive isolates (30%). The overall success rate with monotherapy (69% versus 70%), or with modification (20% versus 23%) were equivalent for ceftazidime and imipenem (P = 0.75). The mortality in this series was 5%. Single-agent therapy with either ceftazidime or imipenem is effective for the empirical treatment of febrile episodes in neutropenic patients with solid tumours. Early addition of amikacin and/or vancomycin resolves most failures of the first step. 相似文献
108.
汉江堤防白蚁的危害与防治 总被引:1,自引:0,他引:1
汉江流域气候温和,土质、植被适宜白生长。蚁害威胁到汉江河道堤防的防洪安全和两岸千百万人民的生命财产安全,必须严加防治。其治理办法有挖,寻,灌,烟熏等。施毒烟熏灭蚁行之有效,能省工省力、节省省金,但仍须加强认识,制订规划,配备人员,进行防治技术的科研与创新。 相似文献
109.
110.
A millimetre-wave planar mixer diode compatible with GaAs MESFET based integrated circuit fabrication has been developed. Selective ion implantation was used to optimise the diode and FET doping profiles. A novel feature reported here is the use of a deep implanted buried n+ layer to minimise diode series resistance, yielding diode cutoff frequencies in excess of 500 GHz. Monolithic balanced mixer diodes integrated with an MESFET IF amplifier fabricated by this technique have given 5dB conversion loss at 60 GHz. 相似文献