全文获取类型
收费全文 | 19373篇 |
免费 | 1656篇 |
国内免费 | 488篇 |
专业分类
电工技术 | 616篇 |
综合类 | 1039篇 |
化学工业 | 9172篇 |
金属工艺 | 243篇 |
机械仪表 | 330篇 |
建筑科学 | 1339篇 |
矿业工程 | 144篇 |
能源动力 | 2649篇 |
轻工业 | 1621篇 |
水利工程 | 161篇 |
石油天然气 | 488篇 |
武器工业 | 19篇 |
无线电 | 328篇 |
一般工业技术 | 2629篇 |
冶金工业 | 297篇 |
原子能技术 | 123篇 |
自动化技术 | 319篇 |
出版年
2024年 | 65篇 |
2023年 | 335篇 |
2022年 | 609篇 |
2021年 | 820篇 |
2020年 | 717篇 |
2019年 | 647篇 |
2018年 | 436篇 |
2017年 | 574篇 |
2016年 | 510篇 |
2015年 | 517篇 |
2014年 | 1017篇 |
2013年 | 1006篇 |
2012年 | 1515篇 |
2011年 | 1477篇 |
2010年 | 1211篇 |
2009年 | 1113篇 |
2008年 | 962篇 |
2007年 | 1254篇 |
2006年 | 1030篇 |
2005年 | 950篇 |
2004年 | 813篇 |
2003年 | 738篇 |
2002年 | 535篇 |
2001年 | 455篇 |
2000年 | 426篇 |
1999年 | 374篇 |
1998年 | 300篇 |
1997年 | 236篇 |
1996年 | 186篇 |
1995年 | 128篇 |
1994年 | 140篇 |
1993年 | 122篇 |
1992年 | 90篇 |
1991年 | 62篇 |
1990年 | 37篇 |
1989年 | 16篇 |
1988年 | 22篇 |
1987年 | 12篇 |
1986年 | 12篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1951年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
报道了以茈为荧光探针,探讨小剂量~(60)Co γ射线照射后小鼠胸腺细胞膜流动性的变化。结果表明,剂量在0.25-1.00Gy范围,胸腺细胞膜流动性降低与剂量之间呈明显线性关系。从0.50Gy起,辐照组荧光强度比值I_1/I_2与I_3/I_2与对照组的比较存有显著差异(P<0.05)。提示淋巴细胞膜流动性的变化可作为小剂量辐照早期效应的敏感指标。 相似文献
92.
二硫代磷酸硫化氧钼与硫,磷添加剂的复配特性研究 总被引:1,自引:0,他引:1
研究了二烷基二硫代磷酸硫化氧钼(MoDTP)摩擦改进剂及其与硫、磷、硫-磷型添加剂复合的抗磨减摩性能。试验表明,经过适当复配后,这类合活性元素的添加剂对MoDTP的抗磨减摩性能均有增效作用,同一类型添加剂的活性愈高,增效作用愈显著。同时利用扫描电镜和X-射线能谱仪进行摩擦副表面膜的形貌照相及元素分析,对复合作用的机理进行了初步探讨。 相似文献
93.
F. R. Perioto M. E. T. Alvarez W. A. Araujo M. R. Wolf‐Maciel R. Maciel Filho 《应用聚合物科学杂志》2008,110(6):3544-3551
A new calculation procedure for free‐volume parameters is considered in this work by using viscosity prediction methods and the Levenberg‐Marquardt calculation scheme. All parameters used in the Vrentas–Duda free‐volume theory can be estimated from pure component properties. The prediction results are compared with experimental data for some polymer/solvent systems. The diffusion coefficient calculated by Vrentas–Duda theory can be used in the modeling of membrane separation processes. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
94.
A different newly designed cationic exchange polymer membrane and anionic exchange polymer membrane were introduced, and also the transport properties of these polymeric membranes were investigated in this study. The transport properties of these polymer membranes in contact with ferrocene redox derivatives were estimated by using electrochemical techniques such as cyclicvoltammetry, chronopotentiometry, and chronoamperometry techniques, respectively. The used ferrocene redox substances, which have different functional groups, were (Ferrocenylmethyl) trimethylamonium iodide, FcMA, Ferrocenedimethanol, FcDM, and Ferrocene carboxylic acid, FcCA. It indicated that the performance of a membrane depended on the content of polymer gel, anionic exchange polymer site (20 wt % and 50 wt %) or cationic polymer exchange site (20 wt % and 50 wt %), and the efficiency of the functional groups of cationic and anionic exchange polymer site as well. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
95.
Using nickel-2,2′-dipyridyl complex as a template, N-vinyl-2-pyrrolidone as the metal coordination functional monomer, and ethylene glycol dimethacrylate as the crosslinker, polyvinylidene fluoride (PVDF) hollow fiber ultrafiltration membrane as the supported membrane, metal complex imprinted polymeric membranes were prepared. The association constant of template-monomer interaction in the prepolymerization solution was estimated to be 4.38 × 104 (L/mol)2 by spectrophotometric titration analysis. The attenuated total reflection Fourier transform infrared spectroscopy and scanning electron micrograph characterization indicated that the surface of the support PVDF membrane was completely coated by the imprinted polymer layer after modification. The imprinted membranes exhibited the selective permeability for the template in certain nickel acetate solution. The molecularly imprinted membranes gave higher permeation separation factors at about pH 6, whereas increasing pressure would lower the separation ability. The effects of ion concentration, cations and counterions, ligand selectivity, pH, and trans-membrane pressure were investigated and the permeation performances of the imprinted membranes could be regarded as facilitated transport mechanism. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
96.
A. Mounir EL Sayed A. Yamauchi N. A. Darwish A. A. Abd EL‐Mageed S. F. Halim 《应用聚合物科学杂志》2008,109(5):2988-2993
The charged mosaic polymer membrane (CMM) without reinforcement and the composite charged mosaic polymer membrane (CCMM) with reinforcement were investigated in terms of salt and water transport (permeability). The composite charged mosaic polymer membrane (CCMM) with reinforcement showed a unique transport behavior such as preferential material transport Lp and ω. Water permeability coefficient, Lp and salt permeability coefficient, ω were estimated by taking account of active layer thickness of composite polymer gel. The Lp and ω values of CCMM with reinforcement were larger than those of CMM without reinforcement. On the other hand, the reflection coefficient of CCMM, σ, showed negative value, which suggested preferential material transport to solvent transport. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
97.
98.
99.
100.
超滤膜的改性研究及应用 总被引:14,自引:0,他引:14
随着超滤膜技术的发展,人们对超滤膜提出了各种各样的特性要求,其中解决膜表面的污染问题变得越来越紧迫.超滤膜改性,尤其是在膜表面引入亲水性基团是解决问题的关键.本文从这点出发,结合自身的工作,总结了近年高分子超滤膜改性方面的研究进展,包括表面活性剂在膜表面的吸附改性、等离子体改性、辐照改性、高分子合金和表面化学反应等几种改性方法. 相似文献