全文获取类型
收费全文 | 83056篇 |
免费 | 7880篇 |
国内免费 | 4034篇 |
专业分类
电工技术 | 5198篇 |
技术理论 | 9篇 |
综合类 | 5871篇 |
化学工业 | 14155篇 |
金属工艺 | 4621篇 |
机械仪表 | 5050篇 |
建筑科学 | 6276篇 |
矿业工程 | 2283篇 |
能源动力 | 2520篇 |
轻工业 | 5398篇 |
水利工程 | 1666篇 |
石油天然气 | 4168篇 |
武器工业 | 914篇 |
无线电 | 9987篇 |
一般工业技术 | 9981篇 |
冶金工业 | 4153篇 |
原子能技术 | 944篇 |
自动化技术 | 11776篇 |
出版年
2024年 | 367篇 |
2023年 | 1283篇 |
2022年 | 2417篇 |
2021年 | 3397篇 |
2020年 | 2509篇 |
2019年 | 2189篇 |
2018年 | 2395篇 |
2017年 | 2559篇 |
2016年 | 2295篇 |
2015年 | 3306篇 |
2014年 | 3893篇 |
2013年 | 4874篇 |
2012年 | 5223篇 |
2011年 | 5566篇 |
2010年 | 4966篇 |
2009年 | 4938篇 |
2008年 | 4701篇 |
2007年 | 4512篇 |
2006年 | 4713篇 |
2005年 | 3889篇 |
2004年 | 2944篇 |
2003年 | 2793篇 |
2002年 | 3076篇 |
2001年 | 2732篇 |
2000年 | 2099篇 |
1999年 | 2121篇 |
1998年 | 1711篇 |
1997年 | 1436篇 |
1996年 | 1244篇 |
1995年 | 1061篇 |
1994年 | 772篇 |
1993年 | 669篇 |
1992年 | 505篇 |
1991年 | 376篇 |
1990年 | 275篇 |
1989年 | 256篇 |
1988年 | 206篇 |
1987年 | 122篇 |
1986年 | 101篇 |
1985年 | 97篇 |
1984年 | 47篇 |
1983年 | 39篇 |
1982年 | 50篇 |
1981年 | 40篇 |
1980年 | 35篇 |
1979年 | 24篇 |
1977年 | 16篇 |
1976年 | 19篇 |
1974年 | 13篇 |
1973年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
原位聚合沉积透明导电聚苯胺薄膜的研究进展 总被引:4,自引:0,他引:4
苯胺在化学氧化聚合过程中,可自发地聚合沉积在不同基体表面,形成透明导电聚苯胺薄膜。重点介绍近年来国内外在玻璃、聚合物、纤维织物和二氧化硅基体表面原位聚合沉积透明导电聚苯胺薄膜的研究进展,并探讨了反应机理。展望了透明导电聚苯胺薄膜在光电器件和微电子器件领域的应用前景。 相似文献
994.
995.
Preparation of HDPE/SEBS‐g‐MAH and its effect on mechanical properties of HDPE/wood flour composites
In this article, high density polyethylene/styrene‐ethylene‐butylene‐styrene block copolymer blends (HDPE/SEBS) grafted by maleic anhydride (HDPE/SEBS‐g‐MAH), which is an effective compatibilizer for HDPE/wood flour composites was prepared by means of torque rheometer with different contents of maleic anhydride (MAH). The experimental results indicated that MAH indeed grafted on HDPE/SEBS by FTIR analysis and the torque increased with increasing the content of maleic anhydride and dicumyl peroxide (DCP). Styrene may increase the graft reaction rate of MAH and HDPE/SEBS. When HDPE/SEBS MAH was added to HDPE/wood flour composites, tensile strength and flexural strength of composites can reach 25.9 and 34.8 MPa in comparison of 16.5 and 23.8 MPa (without HDPE/SEBS‐g‐MAH), increasing by 157 and 146%, respectively. Due to incorporation of thermoplastic elastomer in HDPE/SEBS‐g‐MAH, the Notched Izod impact strength reached 5.08 kJ m?2, increasing by 145% in comparison of system without compatibilizer. That HDPE/SEBS‐g‐MAH improved the compatibility was also conformed by dynamic mechanical measurement. Scanning electron micrographs provided evidence for strong adhesion between wood flour and HDPE matrix with addition of HDPE/SEBS‐g‐MAH. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
996.
997.
聚合物流变性能对共注射成型的影响 总被引:3,自引:0,他引:3
在共注射成型多相分层流动充模成型机理的基础上,揭示了芯壳层熔体对共注射成型的分层界面形貌和芯层熔体前沿突破的影响,并模拟了芯壳层熔体粘度比对共注射成型的影响,建立了芯壳层熔体粘度与分层界面和前沿移动界面菜貌的关系。本文的模拟研究结果与一些文献的实验结果相吻合。 相似文献
998.
The preparation of near stoichiometric spinel and alumina-rich spinel composites from Al2 O3 and MgO powders with the addition of Na3 AlF6 up to 4 wt% in the temperature range 700°–1600°C was studied; 98 wt% spinel containing 72 wt% Al2 O3 can be produced from the mixture of 72 wt% (50 at.%) Al2 O3 + 28 wt% (50 at.%) MgO powders with the addition of 1 wt% Na3 AlF6 fired at 1300°C for 1 h. Spinels containing 81–85 wt% Al2 O3 can be produced from either the mixture of 90 wt% (78 at.%) Al2 O3 + 10 wt% (22 at.%) MgO or the mixture of 95 wt% (88 at.%) Al2 O3 + 5 wt% (12 at.%) MgO powders with the addition of 4 wt% Na3 AlF6 in the temperature range 1300°–1600°C by using a torch-flame firing for 3 min, followed by quenching in water, while the same system under slow cooling in a furnace results in spinel containing 74–76 wt% Al2 O3 . Microscopic studies indicate that the alumina-rich spinel composites consist of a continuous majority spinel phase and an isolated minority corundum phase, regardless of slow cooling in a furnace or quenching in water. 相似文献
999.
Pengjian Zuo Jun Zhao Yulin Ma Xinqun Cheng Pengfei Shi Tsutomu Takamura 《Electrochimica acta》2006,52(4):1527-1531
The SiMn-graphite composite powder was prepared by mechanical ball milling and its electrochemical performances were evaluated as the candidate anode materials for lithium ion batteries. It is found that the cyclic performance of the composite materials is improved significantly compared to SiMn alloy and pure silicon. The heat treatment of the electrodes is beneficial for enhancing the cyclic stabilities. The SiMn-20 wt.% graphite composite electrode after annealing at 200 °C has an initial reversible capacity of 463 mAh g−1 and a charge-discharge efficiency of 70%. Moreover, the reversible capacity maintains 426 mAh g−1 after 30 cycles with a coulomb efficiency of over 97%. The phase structure and morphology of the composite were analyzed by X-ray diffraction (XRD) and scanning electron microscopy. The lithiation/delithiation behavior was investigated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. The composite materials appear to be promising candidates as negative electrodes for lithium rechargeable batteries. 相似文献
1000.
A novel method was used to synthesize adjustable‐molecular‐weight polycaprolactams with monocarboxyl end groups. The reaction device and conditions are discussed. The products were characterized by Fourier transform infrared spectroscopy, 1H‐NMR spectroscopy, high‐resolution pyrolysis gas chromatography–mass spectrometry, and wide‐angle X‐ray diffraction. The thermal properties were studied by differential scanning calorimetry and thermogravimetric analysis. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 722–727, 2004 相似文献