全文获取类型
收费全文 | 23110篇 |
免费 | 1862篇 |
国内免费 | 1098篇 |
专业分类
电工技术 | 1284篇 |
综合类 | 1505篇 |
化学工业 | 4043篇 |
金属工艺 | 1603篇 |
机械仪表 | 1337篇 |
建筑科学 | 1689篇 |
矿业工程 | 836篇 |
能源动力 | 538篇 |
轻工业 | 1513篇 |
水利工程 | 401篇 |
石油天然气 | 1707篇 |
武器工业 | 221篇 |
无线电 | 2470篇 |
一般工业技术 | 2917篇 |
冶金工业 | 1243篇 |
原子能技术 | 231篇 |
自动化技术 | 2532篇 |
出版年
2024年 | 119篇 |
2023年 | 409篇 |
2022年 | 745篇 |
2021年 | 1021篇 |
2020年 | 779篇 |
2019年 | 676篇 |
2018年 | 686篇 |
2017年 | 778篇 |
2016年 | 693篇 |
2015年 | 983篇 |
2014年 | 1191篇 |
2013年 | 1330篇 |
2012年 | 1410篇 |
2011年 | 1620篇 |
2010年 | 1389篇 |
2009年 | 1328篇 |
2008年 | 1176篇 |
2007年 | 1269篇 |
2006年 | 1255篇 |
2005年 | 1073篇 |
2004年 | 690篇 |
2003年 | 587篇 |
2002年 | 599篇 |
2001年 | 527篇 |
2000年 | 528篇 |
1999年 | 591篇 |
1998年 | 454篇 |
1997年 | 411篇 |
1996年 | 371篇 |
1995年 | 339篇 |
1994年 | 294篇 |
1993年 | 181篇 |
1992年 | 152篇 |
1991年 | 98篇 |
1990年 | 72篇 |
1989年 | 57篇 |
1988年 | 62篇 |
1987年 | 39篇 |
1986年 | 26篇 |
1985年 | 14篇 |
1984年 | 13篇 |
1983年 | 13篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1959年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
131.
Controlling Synergistic Oxidation Processes for Efficient and Stable Blue Thermally Activated Delayed Fluorescence Devices 下载免费PDF全文
132.
133.
Tumor Therapy: Bifunctional Platinated Nanoparticles for Photoinduced Tumor Ablation (Adv. Mater. 46/2016) 下载免费PDF全文
134.
Blue OLEDs: Controlling Synergistic Oxidation Processes for Efficient and Stable Blue Thermally Activated Delayed Fluorescence Devices (Adv. Mater. 35/2016) 下载免费PDF全文
135.
Xiang Ma Qiang Li Yu-Chao Cui An-Qi Ni 《International Journal of Pavement Engineering》2018,19(4):355-361
The objective of this study is to evaluate the approaches to improve the durability and strength of the porous asphalt through laboratory testing. Porous asphalt specimens were prepared using three types of binders: high-viscosity binder (HVB), PG76-22 and PG70-22. Various additives: fibre, hydrated lime and DBS polymer, were utilised in the porous asphalt. Comprehensive laboratory tests, including strength test, binder draindown test, Cantabro abrasion test, moisture susceptibility test, rutting test, thermal stress restrained sample test, and permeability test, were conducted. It is found that HVB significantly improved the overall performance of the porous asphalt; DBS additive improved its high-temperature performance, but lowered the cracking resistance at low temperature as well as the durability; fibre enhanced its durability and anti-cracking performance at low temperature; hydrated lime improved its moisture stability while weakening its durability. It is concluded that HVB and polyester fibre should be used in all porous asphalt; DBS additive is good for porous asphalt in high-temperature areas, and hydrated lime can be added to porous asphalt in rainy areas. 相似文献
136.
Effects of Cu on Microstructures,Mechanical, and Magnetic Properties of Fe–Ni–P Alloys Fabricated by Liquid Phase Sintering 下载免费PDF全文
The Fe–Ni–P–Cu alloys with different copper content (0, 0.5, 1, and 2 wt%) are fabricated by liquid phase sintering (LPS) at 950 °C. The nano‐Cu powder is mechanically mixed for 90 min with Fe–Ni–P composite powder using the ethanol as the medium. The microstructure, microhardness and compressive properties of Fe–Ni–P–Cu alloys are investigated. The results indicate that the copper is beneficial to improve the mechanical properties of sintered specimens. The sample contains a small amount of γ‐(Fe, Ni) phase when the copper content is 1 wt%, which results in its the highest compressive yield strength (948.1 MPa). The highest microhardness of 371 HV is accessible in Fe–Ni–P–Cu alloy with 2 wt% Cu. The fracture surface analysis indicates that sintered specimens with Cu addition exhibit a typical intergranular mode. 相似文献
137.
通过共混挤出的方法制备了多元复合改性剂(MCM),并将其用于改性废旧高密度聚乙烯(WHDPE),分析了MCM添加量对WHDPE复合体系性能的影响。研究结果表明:随着MCM添加量的增加,复合体系的冲击强度明显增大,拉伸和弯曲强度却逐渐减小,当ωMCM10%后,复合体系的冲击强度提升的幅度及拉伸、弯曲强度下降的幅度均有所减小;随着MCM添加量的增加,复合体系的熔融指数总体呈减小趋势,但对其熔融、结晶行为以及热稳定性能没有造成明显的影响;随着MCM添加量的增加,复合体系的冲击断面出现了明显的韧性断裂特征,但当ωMCM10%后,断面出现团聚现象且韧性断裂特征逐渐消失。 相似文献
138.
Junjia Cui Lin Qi Hao Jiang Guangyao Li Xu Zhang 《International Journal of Material Forming》2018,11(6):839-853
In this work, the numerical simulations and electromagnetic riveting (EMR) experiments were conducted to investigate microstructure evolution and the forming mechanism of adiabatic shear bands (ASBs). And the effects of rivet dies on microstructure distributions in formed heads and mechanical properties of riveted structures were systematically explored. The impact velocity and deformation distribution results demonstrated that the proposed numerical method was accurate and reliable. The simulation results showed the slope angle of rivet dies notably affected the plastic flow of materials, and then determined the microstructure distribution in formed heads. The combined effects of inhomogeneous plastic flow and thermal softening were accounted for the forming of ASBs. The formed heads had two obvious ASBs (upper and lower ASB) for the 40° rivet die and flat rivet die. The formed heads only had the lower ASB and no clear upper for the 60° rivet die and 80° rivet die. The pull-out test results showed that the specific rivet die could improve the mechanical properties of the EMR joints, which contribute to the engineering applications of EMR riveted structures. 相似文献
139.
Kalashnyk Nataliya Ledieu Julian Gaudry Émilie Cui Can Tsai An-Pang Fournée Vincent 《Nano Research》2018,11(4):2129-2138
Nano Research - The formation of long-range ordered aperiodic molecular films on quasicrystalline substrates is a new challenge that provides an opportunity for further surface functionalization.... 相似文献
140.
Influence maximization of temporal social networks (IMT) is a problem that aims to find the most influential set of nodes in the temporal network so that their information can be the most widely spread. To solve the IMT problem, we propose an influence maximization algorithm based on an improved K-shell method, namely improved K-shell in temporal social networks (KT). The algorithm takes into account the global and local structures of temporal social networks. First, to obtain the kernel value Ks of each node, in the global scope, it layers the network according to the temporal characteristic of nodes by improving the K-shell method. Then, in the local scope, the calculation method of comprehensive degree is proposed to weigh the influence of nodes. Finally, the node with the highest comprehensive degree in each core layer is selected as the seed. However, the seed selection strategy of KT can easily lose some influential nodes. Thus, by optimizing the seed selection strategy, this paper proposes an efficient heuristic algorithm called improved K-shell in temporal social networks for influence maximization (KTIM). According to the hierarchical distribution of cores, the algorithm adds nodes near the central core to the candidate seed set. It then searches for seeds in the candidate seed set according to the comprehensive degree. Experiments show that KTIM is close to the best performing improved method for influence maximization of temporal graph (IMIT) algorithm in terms of effectiveness, but runs at least an order of magnitude faster than it. Therefore, considering the effectiveness and efficiency simultaneously in temporal social networks, the KTIM algorithm works better than other baseline algorithms. 相似文献