全文获取类型
收费全文 | 1937篇 |
免费 | 60篇 |
国内免费 | 6篇 |
学科分类
工业技术 | 2003篇 |
出版年
2024年 | 6篇 |
2023年 | 18篇 |
2022年 | 50篇 |
2021年 | 67篇 |
2020年 | 45篇 |
2019年 | 50篇 |
2018年 | 83篇 |
2017年 | 65篇 |
2016年 | 81篇 |
2015年 | 32篇 |
2014年 | 61篇 |
2013年 | 130篇 |
2012年 | 95篇 |
2011年 | 130篇 |
2010年 | 87篇 |
2009年 | 82篇 |
2008年 | 99篇 |
2007年 | 79篇 |
2006年 | 81篇 |
2005年 | 57篇 |
2004年 | 45篇 |
2003年 | 35篇 |
2002年 | 46篇 |
2001年 | 18篇 |
2000年 | 26篇 |
1999年 | 21篇 |
1998年 | 23篇 |
1997年 | 18篇 |
1996年 | 17篇 |
1995年 | 22篇 |
1994年 | 18篇 |
1993年 | 31篇 |
1992年 | 21篇 |
1991年 | 21篇 |
1990年 | 28篇 |
1989年 | 17篇 |
1988年 | 17篇 |
1987年 | 21篇 |
1986年 | 16篇 |
1985年 | 20篇 |
1984年 | 16篇 |
1983年 | 18篇 |
1982年 | 21篇 |
1981年 | 22篇 |
1980年 | 13篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 9篇 |
1967年 | 2篇 |
排序方式: 共有2003条查询结果,搜索用时 15 毫秒
1.
2.
The graft copolymerization of methyl methacrylate onto natural rubber (NR) was carried out varying the concentration of monomer, initiator, thiourea, and silver nitrate over a wide range. The grafting reaction was temperature-dependent. From the Arrhenius plot, the overall energy of activation was computed. A suitable reaction scheme and rate expression for the rate of polymerization was suggested. 相似文献
3.
The mechanism of the hypolipidemic effect of n-3 fatty acids was studied using isolated rat hepatocytes maintained in culture. EPA and DHA caused a significant reduction in the incorporation of 3[H]-leucine into apoB associated with the VLDL produced by hepatocytes in culture when compared to that in presence of palmitic acid. Presence of indomethacin, an inhibitor of cyclo-oxygenase reversed the effect of EPA on VLDL synthesis while diethyl carbamazine an inhibitor of lipoxygenase did not show any effect suggesting that the effect of EPA may be mediated through prostaglandins. This was further tested by invivo experiments where animals were fed fish oil containing diet with and without aspirin, which inhibits formation of prostaglandins. The incorporation of 3[H]-leucine into apo B and 14[C]-acetate into cholesterol of VLDL produced by hepatocytes from aspirin treated animals were significantly high. The reversal of the effect of n-3 fatty acids by agents which inhibit the formation of prostaglandin suggests that the n-3 fatty acids may exert their effect on VLDL production by liver cells through prostaglandins. 相似文献
4.
5.
Poly(ethylene aspartate) [PEA] was synthesized by the melt condensation of D,L-aspartic acid and ethylene glycol. PEA containing pendent amino and carbonyl groups in its repeating chain was used as the polymeric ligand for complexation with transition metal ions, viz. Co(II), Ni(II), Cu(II), Mn(II), Zn(II), Cd(II), Ca(II), Mg(II), Pb(II) and Hg(II). Complexation was found to be most effective in DMSO. The resulting polyester-metal complexes were solid coloured materials which have been characterized by IR spectroscopy, elemental analysis and magnetic susceptibility measurements. The thermal stability of the polyester-metal complexes was investigated by thermogravimetric analysis (TGA). On the basis of the physico-chemical studies, an oxygen and nitrogen coordinated structure for the polyester-metal complexes is proposed. 相似文献
6.
7.
In this paper we design a dynamic dictionary for
the priced information model initiated by Charikar et al. Assume that a set S consisting of n elements is given such that
each element has an associated price, a positive real number. The cost of performing an operation on elements of S is a function
of their prices. The cost of an algorithm is the sum of the costs of
all operations it performs. The objective is to design algorithms
which incur low cost. In this model we propose a dynamic dictionary, supporting
search, insert and delete, for keys drawn from a linearly ordered set.
As an application we show that the dictionary can be used in
computing the trapezoidal map of a set of line segments, a fundamental problem in
computational geometry. 相似文献
8.
9.
10.
Microhardness measurements have been performed on untreated (virgin) and electrically stressed, solvent‐cast laboratory‐prepared samples of pure poly(phenylene oxide) (PPO), pure polystyrene (PS), and PPO : PS polyblends with different weight proportions. Results of such measurement on untreated polyblend sample show that microhardness (Hv) increases with increase in the content of PS up to 10 wt %, which attributed to the existence of homogeneous phase morphology. However, this feature is not observable in samples containing higher content of PS. Electrical stress is found to modify considerably the mechanical property of polymer. The effect of electric field on the microhardness of such samples (PPO : PS :: 90 : 10) has been characterized by the existence of a peak. Trapping of charge carriers in electrically stressed samples imparts hardening to the polyblend up to an applied step field of 190 kV/cm. However, the excessive charging beyond this step field value destroys this characteristic. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献