全文获取类型
收费全文 | 5254篇 |
免费 | 636篇 |
国内免费 | 200篇 |
专业分类
电工技术 | 235篇 |
综合类 | 297篇 |
化学工业 | 1870篇 |
金属工艺 | 138篇 |
机械仪表 | 72篇 |
建筑科学 | 142篇 |
矿业工程 | 68篇 |
能源动力 | 181篇 |
轻工业 | 1557篇 |
水利工程 | 80篇 |
石油天然气 | 132篇 |
武器工业 | 30篇 |
无线电 | 252篇 |
一般工业技术 | 583篇 |
冶金工业 | 173篇 |
原子能技术 | 24篇 |
自动化技术 | 256篇 |
出版年
2024年 | 43篇 |
2023年 | 111篇 |
2022年 | 165篇 |
2021年 | 207篇 |
2020年 | 234篇 |
2019年 | 178篇 |
2018年 | 186篇 |
2017年 | 200篇 |
2016年 | 206篇 |
2015年 | 165篇 |
2014年 | 253篇 |
2013年 | 305篇 |
2012年 | 397篇 |
2011年 | 368篇 |
2010年 | 268篇 |
2009年 | 258篇 |
2008年 | 237篇 |
2007年 | 319篇 |
2006年 | 303篇 |
2005年 | 270篇 |
2004年 | 213篇 |
2003年 | 193篇 |
2002年 | 201篇 |
2001年 | 137篇 |
2000年 | 132篇 |
1999年 | 102篇 |
1998年 | 88篇 |
1997年 | 66篇 |
1996年 | 60篇 |
1995年 | 56篇 |
1994年 | 49篇 |
1993年 | 23篇 |
1992年 | 23篇 |
1991年 | 17篇 |
1990年 | 12篇 |
1989年 | 9篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1959年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有6090条查询结果,搜索用时 10 毫秒
1.
Aggregates of carbon black (CB) in a polymer matrix have a tendency to form a CB network. The dynamic mechanical properties of binary systems of chlorinated polyethylene (CPE) and CB or 3,9‐bis{1,1‐dimethyl‐2[β‐(3‐tert‐butyl‐4‐hydroxy‐5‐methylphenyl)propionyloxy]ethyl}‐2,4,8,10‐tetraoxaspiro[5,5]‐undecane (AO‐80) and their ternary systems were investigated. It was found that the dynamic mechanical properties of those systems depend on the colloidal properties, surface oxides, and surface modification of CB. For binary systems of CPE and CB, oxidized CB gives a high modulus at low strain amplitude and a large Payne effect compared with untreated CB. In contrast, the reverse effect was observed for their ternary systems. Consequently, a good micro‐dispersion is obtainable by surface modification due to physical adsorption of AO‐80 on oxidized CB particles via hydrogen bonds. © 2003 Society of Chemical Industry 相似文献
2.
MALHIREDDY INDUMADHAVI V. AGTE 《International Journal of Food Science & Technology》1992,27(2):221-228
The average diet in most developing countries is predominantly cereal based. Wheat, rice and millets are major staple foods. Although these diets are sufficient in iron, their low bioavailability is one of the most significant factors for iron deficiency anaemia. Traditional techniques like fermentation show promise in improving iron bioavailability. In vitro ionizable iron was estimated in 31 different combinations of rice, wheat, sorghum, black gram, bengal gram, green gram and coriander in five replicates with or without, fermentation in steamed products. Results indicate that in general cereal pulse combination and fermentation significantly ( P <0.05) increase the per cent ape of ionizable iron. Combination effects dominated in rice whilst fermentation dominated in sorghum. There was a significant reduction ( P <0.05) in phytate phosphorus on fermentation but no loss of tannin. 相似文献
3.
Conducting composites of polythiophene (PTP) and polyfuran (PF) with acetylene black (AB) were prepared via chemical oxidative polymerization of thiophene and furan in a suspension of AB in CHCl3 at room temperature using anhydrous FeCl3 as the oxidant. Formation of PTP and PF and their subsequent incorporation in PTP–AB and PF–AB composite systems were confirmed by FTIR analysis. Scanning electron microscope analysis showed the presence of compact clusters of particles in both composites. Transmission electron micrographs of PTP–AB and PF–AB composites showed formation of globular polymer encapsulated AB particles with average diameters of the order of ~100 nm in both systems. Thermogravimetric analysis revealed that the overall thermal stability varied in the order: AB > PTP–AB > PTP and AB > PF–AB > PF. DC conductivity values for the PTP–AB and PF–AB composites were of the order of 10?2 and 10?3 S cm?1, respectively. Copyright © 2004 Society of Chemical Industry 相似文献
4.
The effect of FEF carbon black as filler on the thermal capacity c, diffusivity a, and thermal conductivity λ, of styrene butadiene rubber (SBR) composites in the temperature range 300–420 K was studied. The filler strongly increases the thermal diffusivity, whilst strongly decreasing the thermal capacity and the thermal conductivity (except at high FEF content ≥80 phr). The influence of the filler on the thermoelastic behaviour of the same composites was also investigated. It was found that the thermoelastic temperature change (ΔT) increased with carbon black concentration as well as the entropy change per unit extension. 相似文献
5.
Peng Dangcong Jin Qiting 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1993,58(1):89-93
The anaerobic digestion of alkaline black liquor from a cereal straw pulping mill was studied in batch (serum bottles) and continuous systems (up-flow anaerobic sludge blanket reactor—UASB). The batch digestion studies confirmed that lignin and related compounds (LRC) in the alkaline black liquor were the main inhibitory substances and could not be decomposed by anaerobic bacteria. At organic loading rates of 5–10 kg COD m?3 day?1, the UASB reactor achieved 50–60% COD removal efficiencies. Gas production was 2–3 dm3 per dm3 of alkaline black liquor. Two different sludge types were examined in the reactor: granular and cluster-like sludges. Sludge in a cluster, which involved many small granules and flocs, tended to form larger aggregates and possessed good settling ability. 相似文献
6.
炭黑填充硬聚氯乙烯的改性 总被引:1,自引:0,他引:1
为使聚氯乙烯具有抗静电性能,采用加入具有导电性填料的方法,但加入大量的填料,会使硬聚氯乙烯的冲击性能降低,加工性能变差。本文是在以炭黑为填料的基础上,研究不同的改性剂和加工助剂改进硬聚氯乙烯的效果,结果表明,加入冲击改性剂和加工助剂后,大大增加了硬聚氯乙烯的冲击强度,且加工性能也得到改善,同时由于炭黑具有补强效果,其拉伸强度和弯曲强度在加入改性剂后也能满足使用要求。 相似文献
7.
竹材丙酮法木质素高效分离技术研究 总被引:6,自引:1,他引:6
在一定的温度、压力条件下,利用丙酮提取竹材中的木质素,丙酮通过蒸馏回收后,可以反复利用;而通过蒸馏,得到的高纯度的木质素是重要的化工原料,整个过程形成一个封闭循环系统,基本上无三废排放;研究结果表明:当丙酮浓度为80%,液固比为10∶1,在最高反应温度160℃下保温3h,降解木质素的效果最佳;为解决制浆造纸行业废水对环境的污染问题提出了一条新的途径。 相似文献
8.
An optimization strategy has been applied to describe the chemical composition at the furnace bottom in the Kraft recovery boiler of a pulp production process. The concentrations of each involved chemical species were calculated through an optimization approach, minimizing the Gibbs free energy of the system. Various systems were proposed and tested, assuming different chemical species and phases number. Because serious initialization problems were found at this stage for some of the proposed systems, an optimization heuristic method (PSO) was used for the first approach to the problem. Once the appropriate phases number and chemical species in the system were determined, the initialization problems disappeared and the use of a deterministic optimization method (SQP) became viable. The proposed approach has shown to be satisfactory to reproduce industrial data and also data reported in the open scientific literature. 相似文献
9.
10.
This paper presents a novel signal processing technique for a square wave temperature modulated carbon black/polymer composite sensor. The technique consists of only two mathematical operations: summing the off- and on-transients of the conductance signals, and subtracting the steady-state conductance signal. The technique has been verified through its application to a carbon black/polyvinylpyrrolidone composite chemoresistor. Identification of water, methanol and ethanol vapours was successfully demonstrated using the peak time of the resultant curves. Furthermore, quantification of those vapours was found to be possible using the height of the peak heights, which was linearly proportional to concentration. The technique does not require zero-gas calibration and thus is superior to previously reported techniques. 相似文献