全文获取类型
收费全文 | 45106篇 |
免费 | 883篇 |
国内免费 | 873篇 |
专业分类
电工技术 | 912篇 |
综合类 | 215篇 |
化学工业 | 7013篇 |
金属工艺 | 3181篇 |
机械仪表 | 1510篇 |
建筑科学 | 1005篇 |
矿业工程 | 245篇 |
能源动力 | 1523篇 |
轻工业 | 2424篇 |
水利工程 | 392篇 |
石油天然气 | 1448篇 |
武器工业 | 7篇 |
无线电 | 4404篇 |
一般工业技术 | 11146篇 |
冶金工业 | 7443篇 |
原子能技术 | 822篇 |
自动化技术 | 3172篇 |
出版年
2021年 | 419篇 |
2020年 | 335篇 |
2019年 | 417篇 |
2018年 | 732篇 |
2017年 | 726篇 |
2016年 | 842篇 |
2015年 | 649篇 |
2014年 | 948篇 |
2013年 | 2582篇 |
2012年 | 1580篇 |
2011年 | 2083篇 |
2010年 | 1675篇 |
2009年 | 1936篇 |
2008年 | 1811篇 |
2007年 | 1914篇 |
2006年 | 1571篇 |
2005年 | 1345篇 |
2004年 | 1275篇 |
2003年 | 1187篇 |
2002年 | 1199篇 |
2001年 | 1226篇 |
2000年 | 1035篇 |
1999年 | 1075篇 |
1998年 | 2184篇 |
1997年 | 1726篇 |
1996年 | 1488篇 |
1995年 | 1029篇 |
1994年 | 788篇 |
1993年 | 798篇 |
1992年 | 620篇 |
1991年 | 605篇 |
1990年 | 536篇 |
1989年 | 497篇 |
1988年 | 382篇 |
1987年 | 408篇 |
1986年 | 373篇 |
1985年 | 384篇 |
1984年 | 314篇 |
1983年 | 312篇 |
1982年 | 310篇 |
1981年 | 304篇 |
1980年 | 354篇 |
1979年 | 348篇 |
1978年 | 296篇 |
1977年 | 418篇 |
1976年 | 641篇 |
1975年 | 313篇 |
1974年 | 295篇 |
1973年 | 312篇 |
1972年 | 273篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
851.
G.?BiresawEmail author A.?Adhvaryu S.?Z.?Erhan C.?J.?Carriere 《Journal of the American Oil Chemists' Society》2002,79(1):53-58
The steel/steel boundary friction properties of soybean oil (SBO) and high-oleic soybean oil (HOSBO) are compared. HOSBO is
significantly more saturated than SBO and more oxidatively stable. Changes in degree of unsaturation affect lateral interactions
of adsorbate molecules, which in turn affects their adsorption and, hence, their boundary lubrication properties. To investigate
this possibility, the free energies of adsorption (ΔG
ads) of SBO, HOSBO, and methyl laurate (ML) were determined from the analysis of friction-derived adsorption isotherms using
the Langmuir and Temkin adsorption models. The results showed a stronger adsorption for the vegetable oils than for ML, an
indication of multiple interactions between the ester groups of the triglycerides and the steel surface. The result also showed
no difference in the ΔG
ads values of SBO and HOSBO obtained using either the Langmuir or Temkin models. This was interpreted as an indication of the
lack of appreciable net lateral interaction between triglyceride adsorbates. 相似文献
852.
Li-Na Zhu Lei Z. Zhang Wen-Zhen Wang Dai-Zheng Liao Peng Cheng Zong-Hui Jiang Shi-Ping Yan 《Inorganic chemistry communications》2002,5(12):434
A novel coordination polymer [Zn(BDC)(H2O)2]n 1 (where BDC = 1,4-benzenedicarboxylate), has been synthesized and characterized by X-ray diffraction. 1 crystallizes in the monoclinic space group C2/c, a=15.09(2) Å, b=5.058(7) Å, c=12.196(16) Å, β=103.62(2)°,
, Z=4. The most striking feature of 1 is that it consists of a high-dimensional network structure constructed from BDC-bridged 1-D chains via interchain hydrogen bonds. The coordination sphere of the zinc(II) ion is a distorted tetrahedron completed by four oxygen atoms from two water molecules and two BDC ligands. BDC adopts the bis-monodentated (syn–anti) coordination mode linking two adjacent zinc(II) ions. 1 shows strong blue photoluminescence as the result of the fluorescence from the intraligand emission excited state. 相似文献
853.
V. M. Girshgorn P. P. Perepechkin G. A. Budnitskii V. G. Sobakin R. K. Kutnova Z. V. Baibakova 《Fibre Chemistry》1986,17(3):197-198
Conclusions The fundamental possibility of an action of a magnetic field on the service properties of a hollow, semipermeable acetate fibres has been demonstrated by treatment of the stream of precipitation bath.As a reason of the magnetic treatment the permeability of the hollow fibres increases by 40–130%; and the empirical quality criterion is increased by 82%.Translated from Khimicheskie Volokna, No. 3, pp. 37–38, May–June, 1985. 相似文献
854.
Z. Koczorowski E. Kucharska-Giziewicz Z. Figaszewski 《Journal of Applied Electrochemistry》1980,10(2):191-196
The characteristics of electrocapillary elements with their filling subjected to vibrations by mechanical and electrical harmonic input signals of frequencies in the range 0.003–30 Hz as well by voltage or pressure jump were studied. The idea of variable pressure or pressure jump measurement by means of an electrocapillary transducer and a model of such a manometer are presented. 相似文献
855.
S.A. Yashnik Z.R. Ismagilov V.V. Kuznetsov V.V. Ushakov V.A. Rogov I.A. Ovsyannikova 《Catalysis Today》2006,117(4):525-535
A synergetic effect in the catalytic activity has been found after palladium introduction in Mn–Al–O systems. The magnitude of the synergetic effect depends on the types of the oxidic manganese species: oxide Mn3O4, spinel (Mn, Mg)[Mn, Al]2O4 or hexaaluminate (Mn, Mg)LaAl11O19. The synergetic effect of Pd and manganese-containing compounds is observed only if palladium is introduced to the low-temperature precursor of the manganese alumina spinel or manganese hexaaluminate. The synergetic effect is not observed when high-temperature samples with formed spinel or hexaaluminate phases are modified with Pd. 相似文献
856.
857.
Polyfunctional monomers (PFMs), namely, trimethylol propane trimethacrylate (TMPTMA), trimethylol propane triacrylate, ethylene glycol dimethacrylate, and diethylene glycol diacrylate were blended with low‐density polyethylene (LDPE) and exposed to different doses of EB irradiation. Fourier transform infrared and ultraviolet and UV–vis spectroscopy of the unirradiated, irradiated, unloaded, and PFMs‐loaded LDPE films were studied under various irradiation doses up to 300 kGy. The degree of crosslinking and oxidative degradation, as measured by the spectroscopic parameters, were dependent on both the irradiation dose and the type of loaded PFMs. For all of the loaded monomers, the extent of crosslinking increased at different rates as a function of irradiation dose. TMPTMA monomer was the most efficient in enhancing the crosslinking of LDPE films compared to the other loaded monomers. However, the unloaded LDPE film showed the least extent of crosslinking. In addition, the EB‐radiation‐induced changes, such as trans‐vinylene formation, a decrease in vinyl and vinylidene unsaturation; and carbonyl double‐bond formation and change in crystallinity were correlated. The importance of these results on the prediction of the role of polyfunctional monomers in the production of crosslinked polymers is discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2025–2035, 2003 相似文献
858.
859.
860.