全文获取类型
收费全文 | 4152篇 |
免费 | 56篇 |
专业分类
电工技术 | 164篇 |
综合类 | 1篇 |
化学工业 | 763篇 |
金属工艺 | 280篇 |
机械仪表 | 363篇 |
建筑科学 | 31篇 |
矿业工程 | 70篇 |
能源动力 | 32篇 |
轻工业 | 130篇 |
水利工程 | 97篇 |
石油天然气 | 113篇 |
无线电 | 451篇 |
一般工业技术 | 891篇 |
冶金工业 | 414篇 |
原子能技术 | 98篇 |
自动化技术 | 310篇 |
出版年
2024年 | 4篇 |
2023年 | 11篇 |
2022年 | 69篇 |
2021年 | 111篇 |
2020年 | 81篇 |
2019年 | 111篇 |
2018年 | 210篇 |
2017年 | 242篇 |
2016年 | 279篇 |
2015年 | 146篇 |
2014年 | 213篇 |
2013年 | 309篇 |
2012年 | 210篇 |
2011年 | 273篇 |
2010年 | 213篇 |
2009年 | 255篇 |
2008年 | 220篇 |
2007年 | 210篇 |
2006年 | 196篇 |
2005年 | 111篇 |
2004年 | 69篇 |
2003年 | 48篇 |
2002年 | 53篇 |
2001年 | 34篇 |
2000年 | 103篇 |
1999年 | 80篇 |
1998年 | 89篇 |
1997年 | 92篇 |
1996年 | 14篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 10篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1976年 | 7篇 |
1975年 | 3篇 |
1974年 | 11篇 |
1973年 | 6篇 |
排序方式: 共有4208条查询结果,搜索用时 15 毫秒
41.
With the help of DTA, DTG elementary analysis of carbonized residues and ESR spectroscopy the influence of anionic form on thermooxidation of trimethylammoniumhydroxyprophyl (TMAHP)–cellulose was studied. At 300°C the percentage of carbon in carbonized residue thermolyzed in oxidative atmosphere is higher than for the sample degraded in inert atmosphere. The percentage of hydrogen decreases simultaneously. The concentration of free radicals in thermolyzed residue also increases due to the presence of oxygen. We propose that oxygen is abstracting the hydrogen atoms from polysaccharide and unpaired electrons on carbon atoms are produced. At 400°C the percentage of carbon in residues prepared at inert atmosphere is higher than for residue formed at oxidative atmosphere. Also the concentration of free radicals in thermolyzed residues obtained in inert atmosphere is greater than for those from oxidative ones. That is why suppose that at this temperature oxygen is bonded to polysaccharide residue and free radicals are terminated. From the semiquantitative DTA we can make the following sequence of samples according to their increasing thermooxidative effect: unmodified cellulose < A–HSO < A–Br? < A–I? < A–NO < A–H2PO < A–CH3COO? < A–HCO < A–F? < A–Cl?1 < A–OHp?. 相似文献
42.
Summary The synthesis is reported of copolymers of styrene with methacrylic acid and of methyl methacrylate with methacrylic acid by radical copolymerization, of copolymers of methyl methacrylate with methacrylic acid by partial alkaline hydrolysis of poly(methyl methacrylate), and of block copolymers of styrene with methacrylic acid. Modified titration curves of all these copolymers were recorded in water and water-ethanol solutions. In a solution containing 50 mass.% ethanol, only small differences could be observed between the potentiometric behaviour of the individual copolymers and polymethacrylic acid. Also, there were no essential differences in any of the solvents used between the potentiometric behaviour of block copolymers of styrene with methacrylic acid, on the one hand, and polymethacrylic acid, on the other. On the contrary, maxima and minima were always observed on the modified titration curves of statistical copolymers with a higher content of the hydrophobic comonomer in solutions with a high water content. Thus, using the modified titration curves, it is possible to decide whether a given copolymer is of the block or statistical type. 相似文献
43.
V.?P.?BessmeltsevEmail author M.?V.?Maksimov V.?V.?Vileiko N.?V.?Goloshevskii V.?S.?Terent’ev 《Optoelectronics, Instrumentation and Data Processing》2018,54(6):531-537
Implementation of a laser scanning confocal microscope is described, where the specimen is scanned by an array of illuminating beams, which significantly increases the velocity of object image construction. The array formation is provided by using a diffractive optical element. Scanning by the array of laser beams over the specimen is performed by galvanometric scanners with moving refractive plane-parallel plates. Owing to application of such a scanning device, the beams in the illuminating channel and the signal beams in the receiving channel pass through one motionless array of confocal diaphragms; as a result, the scanning beams in the specimen plane and the signal beams in the plane of the photodetector matrix can be used without an additional synchronized pair of scanners. The proposed confocal microscope can be applied in problems that require a fast response. 相似文献
44.
Agroskin V. Ya. Bravyi B. G. Vasil’ev G. K. Gur’ev V. I. Kashtanov S. A. Makarov E. F. Sotnichenko S. A. Chernyshev Yu. A. 《Combustion, Explosion, and Shock Waves》2021,57(2):138-149
Combustion, Explosion, and Shock Waves - The ignition of methane–air mixtures with additives of ClF5, ClF3, OF2, and H2O2 (additive content in the mixtures $$\le$$ 1%) is studied by... 相似文献
45.
Combustion, Explosion, and Shock Waves - Mathematical models constructed in the macroscopic approximation are used to perform a theoretical study of volume and wave synthesis in a hybrid mixture... 相似文献
46.
Meerov D. B. Monogarov K. A. Muravyev N. V. Fomenkov I. V. Vasil’ev A. L. Shishov N. I. Pivkina A. N. 《Combustion, Explosion, and Shock Waves》2021,57(5):547-558
Combustion, Explosion, and Shock Waves - The effect of polymer binders on the thermal behavior, combustion, and composition of condensed gasification products of model boron-containing compositions... 相似文献
47.
Erika Leitel Wolfgang Hübner Karsten P. Thiessen Ju. B. Makari
ev A. G. Akimov 《工业材料与腐蚀》1988,39(1):1-7
Investigation into the passivation mechanism of iron in phosphate electrolytes on surfaces exposed to erosive attack On iron electrodes in neutral phosphate electrolytes by continuous solid particle impingement a reaction layer is formed within the transition potential region under anodic polarization. XPS and AES investigations show that the reaction layer formed under impingement will be replaced by an oxide layer during the transition into the passive state under simultaneous decrease of the layer thickness. The active/passive transition in phosphate electrolytes may be attached to the equilibrium potential of the reaction . According to this thermodynamic interpretation of both the active/passive transition and the passive/active transition, respectively on iron in presence of phosphate ions may be described as the Fe(II)/Fe(III)-redox reaction with two solid phases, the iron(II)-phosphate phase and the iron(III)-oxide phase. The increase of the interfacial dynamic processes at the solid/liquid interface causes in consequence of the solid particle impingement that thermodynamic laws govern the course of reactions. 相似文献
48.
Wickramaratna Kasun Kubat Miroslav Premaratne Kamal 《Knowledge and Data Engineering, IEEE Transactions on》2009,21(7):985-998
Existing research in association mining has focused mainly on how to expedite the search for frequently co-occurring groups of items in “shopping cart” type of transactions; less attention has been paid to methods that exploit these “frequent itemsets” for prediction purposes. This paper contributes to the latter task by proposing a technique that uses partial information about the contents of a shopping cart for the prediction of what else the customer is likely to buy. Using the recently proposed data structure of itemset trees (IT-trees), we obtain, in a computationally efficient manner, all rules whose antecedents contain at least one item from the incomplete shopping cart. Then, we combine these rules by uncertainty processing techniques, including the classical Bayesian decision theory and a new algorithm based on the Dempster-Shafer (DS) theory of evidence combination. 相似文献
49.
S. V. Zavarzin A. V. Anan’ev A. I. Fadeev M. Yu. Kalenova I. V. Kuznetsov 《Radiochemistry》2017,59(5):448-452
Electrochemical properties of the intermetallic compound URh3 in 0.5–8 M HNO3 solutions were studied by linear voltammetry. The electrochemical characteristics of URh3 in nitric acid solution were determined for the first time using the Tafel equation. URh3 is highly resistant to both chemical and anodic dissolution, which is due to formation of passive films on the electrode surface. All the anodic oxidation processes observed on the electrode led to secondary passivation of the alloy and not to its dissolution. The conclusions based on the electrochemical data were confirmed by experiments in 8 M HNO3. 相似文献
50.
N.?M.?BarbinEmail author A.?M.?Kobelev D.?I.?Terent’ev S.?G.?Alekseev 《Radiochemistry》2017,59(5):507-511
The behavior of actinides (U, Am, Pu) in the course of combustion of radioactive graphite in steam was studied by thermodynamic modeling. Thermodynamic modeling was performed using TERRA program in the temperature interval from 373 to 3273 K to determine the possible composition of volatile actinide species formed in the course of graphite utilization by heating in steam. The modeling shows that the actinides at high temperatures are present in the following forms: U, as UO3 and UO2 vapors and as UO3 – and UO2 + ions; Am, as Am vapor; and Pu, as PuO2 and PuO vapors and as ionized PuO+. The main reactions within separate phases and at the interface were revealed, and their equilibrium constants were determined. 相似文献