全文获取类型
收费全文 | 5061篇 |
免费 | 245篇 |
国内免费 | 19篇 |
专业分类
电工技术 | 52篇 |
技术理论 | 1篇 |
综合类 | 269篇 |
化学工业 | 2832篇 |
金属工艺 | 31篇 |
机械仪表 | 21篇 |
建筑科学 | 108篇 |
矿业工程 | 7篇 |
能源动力 | 9篇 |
轻工业 | 1549篇 |
水利工程 | 3篇 |
石油天然气 | 67篇 |
武器工业 | 4篇 |
无线电 | 17篇 |
一般工业技术 | 325篇 |
冶金工业 | 15篇 |
原子能技术 | 3篇 |
自动化技术 | 12篇 |
出版年
2024年 | 7篇 |
2023年 | 23篇 |
2022年 | 83篇 |
2021年 | 86篇 |
2020年 | 101篇 |
2019年 | 114篇 |
2018年 | 77篇 |
2017年 | 118篇 |
2016年 | 78篇 |
2015年 | 119篇 |
2014年 | 228篇 |
2013年 | 328篇 |
2012年 | 299篇 |
2011年 | 333篇 |
2010年 | 228篇 |
2009年 | 223篇 |
2008年 | 212篇 |
2007年 | 336篇 |
2006年 | 360篇 |
2005年 | 293篇 |
2004年 | 269篇 |
2003年 | 243篇 |
2002年 | 234篇 |
2001年 | 184篇 |
2000年 | 138篇 |
1999年 | 145篇 |
1998年 | 113篇 |
1997年 | 90篇 |
1996年 | 58篇 |
1995年 | 48篇 |
1994年 | 31篇 |
1993年 | 28篇 |
1992年 | 28篇 |
1991年 | 9篇 |
1990年 | 20篇 |
1989年 | 16篇 |
1988年 | 5篇 |
1987年 | 8篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 2篇 |
排序方式: 共有5325条查询结果,搜索用时 375 毫秒
1.
2.
Polymers play an important role in the advancement of materials for use in cutting-edge applications. A direct consequence of an increased demand for more sophisticated materials has been a drive toward developing polymers that exhibit a higher level of structural control, especially in terms of the number and type of functionalities provided within the polymer framework. A family of polymers that meets such a challenge is based on the readily available AB2 monomer 2,2-bismethylolpropionic acid (bis-MPA) building block. Due to the ease with which the monomers can be synthesized, an array of multifunctional polymers have been produced including monodisperse dendrimers and dendrons and well-defined linear polymers as well as linear-dendritic hybridizations. This review outlines the evolution of the synthetic strategies for developing novel polymeric architectures based on bis-MPA and their assessment in both solution and substrate-based innovative applications. 相似文献
3.
Wan‐Xia Wu 《Polymer International》2019,68(11):1848-1855
A series of novel aliphatic poly(β‐thioether ester)s with various methylene group contents were prepared by direct lipase‐catalyzed polycondensation of the monomer with an acid‐labile β‐thiopropionate group. The polycondensation reaction using immobilized lipase B from Candida antarctica was carried out in diphenyl ether at 90 °C. Poly(β‐thioether ester)s with high molecular weights of 20 500–57 000 Da and narrow polydispersities in the range 1.40–1.48 were obtained. Thermogravimetric analysis, differential scanning calorimetry and wide‐angle X‐ray diffraction were used to investigate the thermal properties and crystal structures of these polyesters. All the poly(β‐thioether ester)s were semicrystalline polymers and thermally stable up to at least 200 °C. In vitro degradation studies showed that they can rapidly degrade under acidic conditions by the hydrolysis of the β‐thiopropionate groups, suggesting their potential as acid‐degradable polymeric materials. © 2019 Society of Chemical Industry 相似文献
4.
5.
探讨了直纺83 dtex/114 f波浪扁平涤纶全拉伸丝(FDY)的工艺制备过程。试验证明,在熔体输送温度276~282℃,纺丝温度286~290℃,喷丝板规格DIO φ104 mm-114孔、"王"字形,环吹风压10~15 Pa,含油率1.1%~1.2%,卷绕速度3 800~4 200 m/min的工艺参数下纺制83 dtex/114 f波浪扁平涤纶FDY时,生产稳定,满卷率高,外观情况良好,袜带均匀亮丽,可批量生产。此新产品可用于制作高档布艺沙发表层面料,具有抗倒伏、色彩艳丽等功效。 相似文献
6.
7.
Locke Davenport Huyer Serena Mandla Yufeng Wang Scott B. Campbell Bess Yee Christian Euler Benjamin F. Lai A. Dawn Bannerman Dawn S. Y. Lin Miles Montgomery Kayla Nemr Timothy Bender Slava Epelman Radhakrishnan Mahadevan Milica Radisic 《Advanced functional materials》2021,31(6):2003341
Itaconate (ITA) is an emerging powerhouse of innate immunity with therapeutic potential that is limited in its ability to be administered in a soluble form. A library of polyester materials that incorporate ITA into polymer backbones resulting in materials with inherent immunoregulatory behavior is developed. Harnessing hydrolytic degradation release from polyester backbones, ITA polymers result in the mechanism specific immunoregulatory properties on macrophage polarization in vitro. In a functional assay, the polymer-released ITA inhibits bacterial growth on acetate. Translation to an in vivo model of biomaterial associated inflammation, intraperitoneal injection of ITA polymers demonstrate a rapid resolution of inflammation in comparison to a control polymer silicone, demonstrating the value of sustained biomimetic presentation of ITA. 相似文献
8.
涤纶工业丝环吹风改造的设计计算 总被引:2,自引:1,他引:1
应用PET纤维的冷却成形理论 ,结合空气调节的相关知识 ,提出了环吹风的设计计算方法 ,对涤纶工业丝环吹风进行了设计改造 ,满足了纺丝工艺要求 相似文献
9.
通过试验,分析比较了江西Sb2O3、南宁Sb2O3和大连Sb(Ac)3三种缩聚催化剂对聚酯切片质量的影响。试验结果表明,Sb(Ac)3是优良的缩聚催化剂。 相似文献
10.
We investigated liquid crystallization of liquid crystalline polyester BB-5 during isothermal annealing by digital high-fidelity microscope and light scattering. A liquid crystalline spherical domain having a radius of micrometers appeared by annealing at around 180 °C. The domain grew dendritically in all directions. Neighboring liquid crystalline regions coalesced and then interconnected. The interconnected structure changed to a co-continuous two-phase structure with increasing ordering of the liquid crystalline phase, and the interface between the liquid crystalline phase and the isotropic phase became smoother over time. Liquid crystallization stopped before volume filling the whole space, and the liquid crystalline phase and isotropic phase coexisted. The liquid crystalline region became narrower with an increase in the temperature of the liquid crystallization. Such structural development is different from the liquid-liquid phase separation via spinodal decomposition, and it may be attributed to the segregation of non-liquid crystallizable low molecular weight molecules from the growth front by fractionation of the molecular weight distribution during the liquid crystallization in terms of the instability of the diffusion-controlled interface. 相似文献