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91.
92.
The linear viscoelastic properties of copolypropylene (cPP)–clay nanocomposites (cPPCNs) prepared by melt intercalating with different amounts of clay were extensively examined by rheological measurements. Meanwhile, the clay effects on the cPP confinements were first estimated by calculating the activation energy of different cPP moving units, including the whole molecular chain, the chain segment, and smaller unit such as chain link. The results showed that the stability of cPPCNs melts wrecked when the clay loading was above 5 wt %. An increase in clay loading of cPPCNs gave rise to a strong low frequency solid‐like response (G′ > G″). Unlike the matrix polymer, cPPCN5 (with 5 wt % clay) exhibited a relaxation plateau as relaxation time prolonged above 100 s, and displayed a maximal linear modulus. The variations of the activation energy of different cPP moving units revealed that the mobility of cPP molecular chains was restricted by clay layers, while these restrictions were not only related to the clay loadings but also largely depended on the clay dispersion status in the matrix. The motions of cPP chain segments were greatly limited at 3–5 wt % loading of clay, but drastically activated with the addition of 7 wt % clay due to the increasing stacks of clay layers within the matrix. However, it was found that the presence of clay had little effect on the mobility of small cPP moving units such as chain links. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1523–1529, 2006 相似文献
93.
Masashi Shou Hiroyuki Takekawa Dong-Ying Ju Tokio Hagiwara Da-ling Lu Ken-ichi Tanaka 《Catalysis Letters》2006,108(3-4):119-124
Catalytic activity of a 1 wt% Au/TiO2 catalyst is markedly improved by loading a large amount of FeOx, on which the oxidation of CO in excess H2 is selectively promoted at temperature lower than 60 °C. Oxidation of CO with O2 on the FeOx/Au/TiO2 catalyst is markedly enhanced by H2, and H2O moisture also enhances the oxidation of CO but its effect is not so large as the promotion by H2. We deduced that activation of Au/TiO2 catalyst by loading FeOx is not caused by the size effect of Au particles but a new reaction path via hydroxyl carbonyl intermediate is responsible
for the superior activity of the FeOx/Au/TiO2 catalyst. 相似文献
94.
宋继萍 《中国生物制品学杂志》2007,20(9):681-684,687
目的评估免疫细胞素Hu14.18-IL-2对黑色素瘤病人体内免疫作用。方法33位黑色素瘤病人用一种人源化抗神经节苷脂GD-2的单抗与IL-2融合的免疫细胞素进行治疗,按每天0.8、1.6、3.2、4.8、6.0、7.5 mg/m2静脉滴注,连续3 d为一疗程,病情稳定或缓解后,在第5周接受第2疗程治疗。观察病人外周血单核淋巴细胞抗体依赖的细胞毒性、自然杀伤细胞活性、IL-2的体外增殖以及IL-2可溶性受体的变化。结果Hu14.18-IL-2能诱导病人淋巴细胞的吞噬作用,增强外周血中自然杀伤细胞的杀伤能力和数目,使血清中IL-2受体复合体的可溶性受体α链水平上升。结论免疫细胞素Hu14.18-IL-2对黑色素瘤病人具有免疫激活作用。 相似文献
95.
M.A. Migahed M. Abd-El-Raouf A.M. Al-Sabagh H.M. Abd-El-Bary 《Journal of Applied Electrochemistry》2006,36(4):395-402
Four novel non-ionic ethoxylated fatty alkyl amine surfactants (I–IV) were synthesised and investigated as corrosion inhibitors
of carbon steel in 1 M hydrochloric acid solution using gravimetric, open circuit potential and potentiostatic polarisation techniques. The percentage
inhibition efficiency (η%) for each inhibitor increased with increasing concentration until the critical micelle concentration
(cmc) was reached. The maximum inhibition efficiency approached 95.1% in the presence of 400 ppm of the inhibitor (IV). It
was found that the adsorption of the surfactants on carbon steel followed the Langmuir adsorption isotherm. Potentiostatic
polarisation data indicated that these surfactants act as mixed type inhibitors. The values of activation energy (E
a*) of carbon steel dissolution in 1 M HCl were calculated in the absence and presence of 400 ppm of each inhibitor. Finally, scanning electron microscopy (SEM)
was used to examine the surface morphology of polished carbon steel surfaces and those immersed in 1 M HCl in the absence and presence of 400 ppm of inhibitor (IV). 相似文献
96.
97.
Zoltán Varga Jenő Hancsók Gábor Nagy György Pölczmann Dénes Kalló 《Topics in Catalysis》2007,45(1-4):203-206
The hydrodesulphurization (HDS) of dibenzothiophene (DBT), 4-methyl dibenzothiophene (4 M-DBT), 4,6-dimethyl dibenzothiophene
(4,6 DM-DBT) and 4,6-diethyl dibenzothiophene (4,6 DE-DBT) as real gas oil components on NiMo/Al2O3 catalyst was investigated. On the basis of the first order rate constants of HDS of the individual sulphur compounds reactivities
of the investigated compounds decreased in the order DBT ≫ 4 M-DBT > 4,6 DE-DBT ≈ 4,6 DM-DBT. Apparent activation energies
of HDS of above sulphur compounds increased from 80.0 to 120.5 kJ/mol. 相似文献
98.
Removal of chromium (VI) from dilute aqueous solutions by activated carbon developed from Terminalia arjuna nuts activated with zinc chloride 总被引:1,自引:0,他引:1
Different structured activated carbons were prepared from Terminalia arjuna nuts, an agricultural waste, by chemical activation with zinc chloride for the adsorption of Cr(VI) from dilute aqueous solutions. The most important parameter in chemical activation was found to be the chemical ratio (activating agent/precursor, g/g). Carbonization temperature and time are the other two important variables, which had significant effect on the pore structure of carbon. A high surface area of was obtained at a chemical ratio of 300%, carbonization time and temperature of 1 h and 500 °C, respectively. The activated carbon developed shows substantial capability to adsorb Cr(VI) from dilute aqueous solutions. The parameters studied include pH, adsorbent dosage, contact time, and initial concentrations. The kinetic data were best fitted to the Lagergren pseudo-first-order model. The isotherm equilibrium data were well fitted by the Langmuir and Freundlich models. The maximum removal of chromium was obtained at pH 1.0 (about 99% for adsorbent dose of 2 g/l and 10 mg/l initial concentration). 相似文献
99.
In this study, a thiirane resin was synthesized by the reaction of corresponding epoxy resin with KSCN. The synthetic conditions influencing the conversion of epoxy group were systematically investigated, such as the reaction temperature, reaction media, reaction time and the ratio of KSCN to epoxy group. It was found that the conversion of epoxy group increased with the increasing reaction temperature, improving the solubility of the mediate, extending reaction time, and the enhancing ratio of salt (KSCN) to epoxy group. Wherein, the reaction temperature and the ratio of the KSCN to epoxy group were more effective. For example, when the molar ratio of KSCN to epoxy group was equal to 2.0, the conversion of epoxy group got the maximum value, 0.65. In addition, the hot plate method was used to measure the gelling time of the resultant thiirane resin at different temperatures. It was found that the gelling time was reduced to 47–85% times as the corresponding epoxy resin depending on the conversion of the epoxy group, and the curing activation energy was diminished from 39 kJ/mol of epoxy resin to 17 kJ/mol. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4023–4027, 2006 相似文献
100.
We prepared poly(p‐phenylene pyromellitimide) (PMDA–PDA), poly(p‐phenylene 4,4′‐hexafluoroisopropylidene diphthalimide), and their copolyimides with various compositions to explore the relationship between the water sorption and structure. The water sorption behaviors were gravimetrically investigated as a function of composition and temperature and interpreted with a Fickian diffusion model in films. Overall, the water sorption behaviors were strongly dependent on the changes in morphological structure, which originated from the variations in composition. When the content of the bulky hexafluoroisopropylidene group (6FDA) was increased, the water uptake decreased from 5.80 to 3.18 wt %, whereas the diffusion coefficient increased from 3.6 × 10?10 to 11.3 × 10?10 cm2/s. The relatively high water uptake in the PMDA–PDA polyimide film was successfully healed by the incorporation of 6FDA, which may have resulted from the increases in the intermolecular packing order and hydrophobicity. The degree of orientation and crystallinity, which are in‐plane characteristics, were directly correlated to the diffusion coefficient and activation energy in the polyimide film. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3442–3446, 2003 相似文献