全文获取类型
收费全文 | 515篇 |
免费 | 27篇 |
专业分类
综合类 | 11篇 |
化学工业 | 128篇 |
金属工艺 | 6篇 |
机械仪表 | 5篇 |
建筑科学 | 20篇 |
矿业工程 | 1篇 |
能源动力 | 12篇 |
轻工业 | 108篇 |
水利工程 | 6篇 |
石油天然气 | 3篇 |
无线电 | 34篇 |
一般工业技术 | 61篇 |
冶金工业 | 97篇 |
原子能技术 | 2篇 |
自动化技术 | 48篇 |
出版年
2023年 | 8篇 |
2022年 | 21篇 |
2021年 | 34篇 |
2020年 | 4篇 |
2019年 | 15篇 |
2018年 | 18篇 |
2017年 | 13篇 |
2016年 | 12篇 |
2015年 | 11篇 |
2014年 | 20篇 |
2013年 | 36篇 |
2012年 | 29篇 |
2011年 | 31篇 |
2010年 | 11篇 |
2009年 | 18篇 |
2008年 | 15篇 |
2007年 | 21篇 |
2006年 | 22篇 |
2005年 | 13篇 |
2004年 | 15篇 |
2003年 | 12篇 |
2002年 | 15篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 10篇 |
1998年 | 37篇 |
1997年 | 14篇 |
1996年 | 11篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1983年 | 3篇 |
1981年 | 2篇 |
1978年 | 3篇 |
1976年 | 3篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1956年 | 1篇 |
1944年 | 1篇 |
排序方式: 共有542条查询结果,搜索用时 15 毫秒
41.
Fei Yang Stella Raynova Ajit Singh Qinyang Zhao Carlos Romero Leandro Bolzoni 《JOM Journal of the Minerals, Metals and Materials Society》2018,70(5):632-637
Powder metallurgy is a very attractive method for producing titanium alloys, which can be near-net-shape formed and have freedom in composition selection. However, applications are still limited due to product affordability. In this paper, we will discuss a possible cost-effective route, combining fast heating and hot processing, to produce titanium alloys with similar or even better mechanical properties than that of ingot metallurgy titanium alloys. Two titanium alloys, Ti-5Al-5V-5Mo-3Cr (Ti-5553) and Ti-5Fe, were successfully produced from HDH titanium powder and other master alloy powders using the proposed processing route. The effect of the processing route on microstructural variation and mechanical properties have been discussed. 相似文献
42.
Analysis of PCR-based methods for characterization of Listeria monocytogenes strains isolated from different sources 总被引:3,自引:0,他引:3
Cocolin L Stella S Nappi R Bozzetta E Cantoni C Comi G 《International journal of food microbiology》2005,103(2):167-178
Listeria monocytogenes strains, isolated from various sources (food, environment, and animals), were used to test different PCR-based methods to investigate their capability to define the strain origin. RAPD-PCR with three primers and the SAU-PCR method, in which the DNA was first digested with the Sau3A restriction endonuclease and then amplified with a primer designed on the restriction site, were carried out, and the profiles obtained were used to perform cluster analysis. Based on the cluster analysis of Listeria spp. strains, obtained from international collections, the coefficient of similarity was selected. The results obtained showed that the methods tested in the study gave different levels of differentiation between the strains tested. The RAPD protocol using the P1254 primer and the SAU-PCR gave appreciable results only for strains isolated from animals and from a food processing plant in two different periods of the year 2003. Better differentiation was observed using the RAPD-PCR with primer D8635. As a matter of fact, it was able to distinguish L. monocytogenes obtained from different species of animals, different food samples and strains from the same production plant isolated in different periods of the year. Also primer M13 gave positive results, but the coefficient of similarity to use had to be increased to 80%. On the basis of the results observed, RAPD-PCR with primers D8635 and M13 should be considered reliable tools for epidemiological investigations focusing on L. monocytogenes. 相似文献
43.
The objective of this work is proposing a simple thermodynamic model to explain the increase in the solubility limit of the powders of the Cu–Mo systems or other binary systems processed by mechanical alloying. In the regular solution model, the effects of crystalline defects, such as; dislocations and grain boundary produced during milling were introduced. The model gives results that are consistent with the solubility limit extension reported in other works for the Cu–Cr, Cu–Nb and Cu–Fe systems processed by mechanical alloying. 相似文献
44.
The colourimetric pH indicators methyl red and bromocresol green have been immobilised in organic-inorganic silica hybrid matrices prepared by a sol-gel method. The optically transparent sol-gel thin films containing encapsualated dye molecules were deposited onto glass substrates using spin-coating and dip-coating techniques. The organic-inorganic hybrid materials were obtained by co-polymerisation of tetraethoxysilane together with glycidoxypropyltrimethoxysilane as an organically modified sol-gel precursor. Matrix polarity and morphology were varied by using solutions containing different ratios of sol-gel precursors and surfactants. Spectral characterisation of the films was performed using ultra-violet and visible absorption spectroscopy, and the spectral changes in different matrices were identified. The effects of the sol-gel mixtures composition on the mechanical stability and homogeneity of the films, and the colourimetric response to solutions of differing pH were studied. The apparent pKapp values of the immobilised pH indicators were also determined in the different matrices. 相似文献
45.
46.
Stella Mills 《Interacting with computers》2011,23(2):106-116
Traditionally, Christian pastoral care has always been given face-to-face. However, since the Internet made e-mail a common form of correspondence, people have been e-mailing friends to discuss problems and other matters. More formal pastoral care, involving a pastoral minister, has generally remained a face-to-face occurrence. This article explores the possibility of e-mail being used for Christian pastoral care and evaluates one such system being operated in the United Kingdom. The results show that with an empathic and positive response to the e-mails by the pastoral minister, e-mail pastoral care can increase positive emotion, and hence well-being, in the person seeking care. In addition, the religious aspect of Christian pastoral care seems to be important in initialising the minister-person relationship. 相似文献
47.
The proximity and speed of motor traffic passing cyclists in non-separated conditions may be so close and so great as to cause discomfort. A variety of road design and driver behaviour factors may affect overtaking speeds and distances. The investigation presented in this paper builds on previous research and fills gaps in that research by considering the presence of cycle lanes on 20 mph and 30 mph roads, different lane widths, different lane markings, vehicle type, vehicle platooning and oncoming traffic. Data were collected from a bicycle ridden a distance of one metre from the kerb fitted with an ultrasonic distance detector and forward and sideways facing cameras. 相似文献
48.
Suguna Lakshmi Madurai Stella Winnarasi Joseph Asit Baran Mandal John Tsibouklis Boreddy SR Reddy 《Nanoscale research letters》2011,6(1):15-8
The intercalation of captopril (CP) into the interlayers of montmorillonite (MMT) affords an intestine-selective drug delivery
system that has a captopril-loading capacity of up to ca. 14 %w/w and which exhibits near-zero-order release kinetics. 相似文献
49.
Carl Reed Stella Doyungan Brian Ioerger Anna Getchell 《Journal of Stored Products Research》2007,43(4):443-458
Maize was stored for 2 months in chambers maintained at 25 °C to simulate conditions observed in the central part of the “Corn Belt” of the United States when the grain warms because of high summertime temperatures after a period of winter storage. Maize was brought to three moisture contents (m.c.) within the range typically observed in farm and commercial storage, and was inoculated to simulate the amount of storage mold contamination typical of this situation. Certain of the experimental units were packed in insulation so that heat could accumulate within the grain masses to simulate hot spots. The wettest grain heated rapidly and became semi-anaerobic. The hot grain then dried rapidly, with the amount of moisture loss influenced by the ratio of water vapor pressures inside and outside the grain. The hot grain cooled and became more aerobic over time. New infections by storage molds, disappearance of viable field molds, development of kernel damage, and changes in atmospheric gases within the grain masses were correlated with the grain moisture or temperature and the rate at which the moisture and temperature changed. The rate of increase in new kernel damage was as high as 3.3% per week. Both the rate of respiration and the estimated ratio of starch to fat consumed were associated with the mean grain m.c. during the trial, and the estimated ratio of starch to fat consumed was in the range of 2.2/1–2.6/1 in the grain containing 16.6–18.2% m.c. That both fat and starch were consumed calls into question loss estimates based on starch metabolism alone. The fat content of the grain decreased more than 10% in some experimental units, but increased less than 5% in others. The protein content generally increased as other grain constituents were consumed. 相似文献
50.
There are multiple components to the concept of Umwelt experienced by an organism that may constrain the type and structure of communication signals as well as the usefulness of these signals. To illustrate the impact of these multiple environmental components, the authors used signals of the pygmy marmoset (Cebuella pygmaea), a small primate from the western Amazon. The authors summarize studies to show how the physical effects of the habitat; effects of other species, both predators and nonpredators; anthropogenic effects on the communication environment; within-group and between-groups influences other pygmy marmosets exert; and ontogeny influence the structure and usage of vocal signals. Communication within a species can be understood only in consideration of each of these contexts. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献