全文获取类型
收费全文 | 515篇 |
免费 | 65篇 |
国内免费 | 19篇 |
学科分类
工业技术 | 599篇 |
出版年
2024年 | 2篇 |
2023年 | 14篇 |
2022年 | 28篇 |
2021年 | 27篇 |
2020年 | 20篇 |
2019年 | 25篇 |
2018年 | 11篇 |
2017年 | 28篇 |
2016年 | 17篇 |
2015年 | 27篇 |
2014年 | 34篇 |
2013年 | 46篇 |
2012年 | 48篇 |
2011年 | 27篇 |
2010年 | 28篇 |
2009年 | 30篇 |
2008年 | 14篇 |
2007年 | 20篇 |
2006年 | 21篇 |
2005年 | 25篇 |
2004年 | 18篇 |
2003年 | 15篇 |
2002年 | 9篇 |
2001年 | 6篇 |
2000年 | 8篇 |
1999年 | 9篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1984年 | 1篇 |
排序方式: 共有599条查询结果,搜索用时 15 毫秒
21.
Polypropylene (PP)/organic montmorillonite (OMMT) nanocomposites were first prepared through twin-screw extruder and then subjected to multistage stretching extrusion with an assembly of laminating-multiplying elements (LMEs, which divide and recombine polymer melts). The exfoliated efficiency of LMEs on OMMT dispersed in PP matrix was investigated by optical microscopy, scanning electron microscope, transmission electron microscopy and X-ray diffraction. Because of the absence of compatibilizer, molecular chains of PP were not intercalated into the galleries of OMMT during the multistage stretching extrusion. The exfoliation of OMMT was induced by the strong force occurred in LMEs, which can destruct van der Waal’s interaction between the laminate OMMT platelets. The exfoliation degree of OMMT has been improved with the increase of number of LMEs used. The dispersion morphology of OMMT was thermodynamically stable after secondary melt processing. As a result, the mechanical properties of composites have been enhanced with increasing LME number. We realized the exfoliation of OMMT by the function of strong shear field without the incorporation of compatibilizer. 相似文献
22.
Shaoyun Chen Min Xiao Shuanjin Wang Dongmei Han Yuezhong Meng 《Journal of Polymer Research》2012,19(2):9800
Block copolymers of poly (propylene carbonate—cyclohexyl carbonate) (PPC-PCHC) were successfully synthesized by a one-pot
method with the zinc complex catalyst (Zn2G). The IR and 1H-NMR and 13C-NMR spectra verified the introducing of PCHC segments in the copolymers. The GPC curves of the copolymers appeared only
one peak and the DSC results showed three glass transition temperatures at 40 °C, 66 °C and 115 °C, indicating the three-block
copolymer structure. TGA tests revealed that the thermal decomposition temperature of the synthesized block copolymers increased
up to about 300 °C. The mechanical properties proved to be also enhanced greatly as evidenced by static and dynamic mechanical
tests. The thermal and mechanical properties of the resultant block copolymers lay between those of PPC and PCHC, demonstrating
the desired properties of a polymer can be achieved via block copolymerization. 相似文献
23.
Yongxiang Hong Xixi Cai Biao Shao Jing Hong Shaoyun Wang Pingfan Rao 《European Food Research and Technology》2013,237(3):457-465
A novel trypsin inhibitor with considerable thermal and pH stability, designated Glytine, was isolated from seeds of the Chinese black soybean Glycine max (L.) Merr. The purification procedure involved ammonium sulfate precipitation, ion-exchange chromatography on CM-Sephadex C-50, gel filtration chromatography on Sephacryl S-200HR, and gel filtration chromatography on POROS HS-20. The 20 N-terminal amino acid sequences were determined to be DEYSKPCCDLCMCTRRCPPQ, demonstrating close homology with the sequences of leguminous trypsin inhibitors. The molecular mass and isoelectric point of the inhibitor were estimated by SDS-PAGE and isoelectric focusing to be 19.9 kDa and 6.2, respectively. Trypsin could be completely inhibited by Glytine when the weight ratio was 1.5. The inhibitory activity of Glytine was unaffected by exposure to temperatures up to 100 °C, or within the pH range 2–12. Besides trypsin–chymotrypsin inhibition activity, Glytine demonstrated other biological activities including antiproliferative activity against tumor cells including human liver hepatoma cells Bel-7402 and neuroblastoma cells SHSY5Y. In addition, the inhibitor showed antifungal activity against Pythium aphanidermatum, Fusarium oxysporum, Alternaria alternata (Fr.) Keiss, Fusarium solani, and Botrytis cinerea. This study extended research on leguminous trypsin–chymotrypsin inhibitor and suggested exploitable potential. 相似文献
24.
Polyaniline (PANI)/silver (Ag) nanocomposites containing PANI nanofibers decorated with well‐dispersed Ag nanoparticles were obtained with interfacial polymerization. It was interesting that silver nitride affected not only the diameter and crystallinity of the PANI nanofibers but also their room‐temperature conductivity. The conductivity increased with increasing Ag loading up to 10 (molar ratio of aniline to silver nitride), but the conductivity moderately decreased with further increasing Ag loading. Scanning electron microscopy and X‐ray diffraction analysis results indicate that the diameter of the PANI nanofibers became smaller and smaller, and their crystallinity got better and better with increasing Ag loading. However, Fourier transform infrared analysis proved that the balance of oxidized and reduced units of PANI became big with increasing Ag loading, which may have resulted in the decreasing conductivity of PANI. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
25.
26.
Shaoyun Wang 《Trends in Food Science & Technology》2010,21(1):52
27.
本文总结分析了某铜矿酸浸渣采用硫脲溶液浸出,锌粉置换回收银的主要特点,针对其特点提出了处理该类废渣回收银的技术措施。 相似文献
28.
29.
研究了313K时40%(质量分数)哌嗪(PZ)、N-氨乙基哌嗪(N-AEPZ)和羟乙基哌嗪(HEPZ)溶液吸收CO2性能以及30%AEE+10%PZ、30%AEE+10%N-AEPZ和30%AEE+10%HEPZ溶液对CO2的吸收性能。考察了吸收速率、吸收量、吸收时间、温度变化和PZ及其衍生物含量之间的相互关系。考察了解吸量与解吸时间的关系,解吸温度为393K。结果表明,分子结构中的多氨基基团有利于提高吸收性能;在复合体系中,N-AEPZ为主吸收作用,PZ与AEE共同作用,HEPZ为助吸收作用,提高主吸收组分的浓度有利于提高溶液的吸收能力,其中30%AEE+10%PZ的混胺溶液具有良好的吸收和解吸性能。 相似文献
30.
The preparation of a novel polymeric photostabilizer was carried out via the vibromilling of poly(vinyl chloride) (PVC) powder, a reactive light stabilizer (r‐LS), and a peroxide initiator in ball‐containing jars with a planetary ball mill for a certain time. The effects of the initiator content, milling time, and temperature on the grafting ratio were studied with gravimetric analysis and intrinsic viscosity measurements. Fourier transform infrared and ultraviolet–visible spectra were used to investigate the structural development of the mixture of the r‐LS and PVC during vibromilling. The results showed that the r‐LS was grafted onto PVC chains successfully, and the aforementioned factors had a significant effect on the grafting ratio. The optimum preparation conditions were 0.5 wt % initiator, 8 h, and 20°C. A grafting mechanism is proposed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献