全文获取类型
收费全文 | 489篇 |
免费 | 6篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 73篇 |
金属工艺 | 125篇 |
机械仪表 | 11篇 |
建筑科学 | 6篇 |
能源动力 | 25篇 |
轻工业 | 78篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 7篇 |
一般工业技术 | 97篇 |
冶金工业 | 40篇 |
原子能技术 | 2篇 |
自动化技术 | 27篇 |
出版年
2017年 | 7篇 |
2015年 | 4篇 |
2014年 | 5篇 |
2013年 | 11篇 |
2012年 | 7篇 |
2011年 | 9篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 10篇 |
2007年 | 13篇 |
2006年 | 13篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 10篇 |
2000年 | 12篇 |
1999年 | 13篇 |
1998年 | 13篇 |
1997年 | 22篇 |
1996年 | 12篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 10篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 19篇 |
1989年 | 9篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 11篇 |
1980年 | 10篇 |
1979年 | 9篇 |
1978年 | 18篇 |
1977年 | 5篇 |
1976年 | 16篇 |
1975年 | 11篇 |
1974年 | 19篇 |
1973年 | 11篇 |
1972年 | 7篇 |
1971年 | 11篇 |
1970年 | 18篇 |
1969年 | 3篇 |
1956年 | 4篇 |
1923年 | 3篇 |
1918年 | 3篇 |
排序方式: 共有495条查询结果,搜索用时 15 毫秒
1.
2.
3.
Chr. Bargholtz L. Gerén V. N. Grebenev Yu. B. Gurov V. S. Karpukhin I. V. Laukhin B. V. Martem’yanov V. A. Matveev K. Lindberg V. S. Sopov P. -E. Tegnér B. A. Chernyshev R. R. Shafigullin I. Zartova 《Instruments and Experimental Techniques》2006,49(4):461-467
A zero-degree spectrometer for tagging η mesons on the CELSIUS/WASA facility is described, and its characteristics are presented. Tagging of η mesons is performed by detecting 3He ions produced by reaction pd → 3Heη close to the production threshold. The low background level (<2%) is in good agreement with the data obtained earlier on the SATURNE accelerator. 相似文献
4.
5.
S Davis H Leirs H Viljugrein N Chr Stenseth L De Bruyn N Klassovskiy V Ageyev M Begon 《Journal of the Royal Society Interface》2007,4(15):649-657
Plague surveillance programmes established in Kazakhstan, Central Asia, during the previous century, have generated large plague archives that have been used to parameterize an abundance threshold model for sylvatic plague in great gerbil (Rhombomys opimus) populations. Here, we assess the model using additional data from the same archives. Throughout the focus, population levels above the threshold were a necessary condition for an epizootic to occur. However, there were large numbers of occasions when an epizootic was not observed even though great gerbils were, and had been, abundant. We examine six hypotheses that could explain the resulting false positive predictions, namely (i) including end-of-outbreak data erroneously lowers the estimated threshold, (ii) too few gerbils were tested, (iii) plague becomes locally extinct, (iv) the abundance of fleas was too low, (v) the climate was unfavourable, and (vi) a high proportion of gerbils were resistant. Of these, separate thresholds, fleas and climate received some support but accounted for few false positives and can be disregarded as serious omissions from the model. Small sample size and local extinction received strong support and can account for most of the false positives. Host resistance received no support here but should be subject to more direct experimental testing. 相似文献
6.
Tests of a linear Equation on the Evaluation of Krypton Friction Experiments at low Pressures and Connections to Viscosity Effects The coefficient of viskosity is nearly constant in the region with STP conditions and is independent of the pressure. This coefficient decreases with lowering the pressure until the region of molecular flow is reached. There we have free molecular‐ or vacuum viscosity. Experiments with the friction of gas have to take in the gas between surfaces which are movabel and parallel. Reactions of the gas with the moving surface cannot be neglected. We made our lab‐examinations of gas friction effects between two rotating cylinders. Generally there is a linear equation of the reciprocal values of viscosities and pressures. Our experiments show a region, where this linear relation is valid. This region has a low limit with coming to molecular flow and an upper limit if the gas is warmed up by friction at higher pressures. 相似文献
7.
By methods of DOT hybridization and polymerase chain reaction (PCR) structures similar to Alu repeats were shown in the genome of fish and lamprey. The fact of the presence of such sections in representatives of many orders of fishes, and also our experimental data allow to suppose that Alu-like structures, similar to 3' region of Alu repeats on mammals, have been already formed in these. The evolutionary significance of described structures has been supposed. 相似文献
8.
The data are provided on the content of carcinogenous N-nitroso compounds in foods manufactured in a region with a high gastric carcinoma incidence. It was found that foods under analysis have a high content of carcinogenous nitroso compounds. The foods were also found to contain N-nitrosopiperidine, a carcinogen inducing tumors of the gastrointestinal tract. 相似文献
9.
Katarzyna Jasieniecka-Gazarkiewicz Kamil Demski Satinder K. Gidda Sylwia Kliska Janusz Niedojado Ida Lager Anders S. Carlsson Elena A. Minina Robert T. Mullen Peter V. Bozhkov Sten Stymne Antoni Bana 《International journal of molecular sciences》2021,22(6)
Arabidopsis thaliana possesses two acyl-CoA:lysophosphatidylethanolamine acyltransferases, LPEAT1 and LPEAT2, which are encoded by At1g80950 and At2g45670 genes, respectively. Both single lpeat2 mutant and double lpeat1 lpeat2 mutant plants exhibit a variety of conspicuous phenotypes, including dwarfed growth. Confocal microscopic analysis of tobacco suspension-cultured cells transiently transformed with green fluorescent protein-tagged versions of LPEAT1 or LPEAT2 revealed that LPEAT1 is localized to the endoplasmic reticulum (ER), whereas LPEAT2 is localized to both Golgi and late endosomes. Considering that the primary product of the reaction catalyzed by LPEATs is phosphatidylethanolamine, which is known to be covalently conjugated with autophagy-related protein ATG8 during a key step of the formation of autophagosomes, we investigated the requirements for LPEATs to engage in autophagic activity in Arabidopsis. Knocking out of either or both LPEAT genes led to enhanced accumulation of the autophagic adaptor protein NBR1 and decreased levels of both ATG8a mRNA and total ATG8 protein. Moreover, we detected significantly fewer membrane objects in the vacuoles of lpeat1 lpeat2 double mutant mesophyll cells than in vacuoles of control plants. However, contrary to what has been reported on autophagy deficient plants, the lpeat mutants displayed a prolonged life span compared to wild type, including delayed senescence. 相似文献
10.
Zircon, ZrSiO4, is a natural mineral used for various applications as a refractory bulk material. It is an excellent feedstock for the plasma
spraying of protective coatings and free-standing bodies. Zircon decomposes on spraying into t-ZrO2 and glassy SiO2, which can be preserved in deposits by fast cooling. This combination of zirconia and silica exhibits properties such as
a high thermal shock resistance, good corrosion resistance, low wettability, etc. The final properties of deposits can be
further enhanced by the addition of other materials such as alumina. For instance, alumina-zircon plasma-sprayed free-standing
pipes have a low gas permeability. Several technical applications are discussed. 相似文献