全文获取类型
收费全文 | 72764篇 |
免费 | 5592篇 |
国内免费 | 2769篇 |
专业分类
电工技术 | 3946篇 |
技术理论 | 6篇 |
综合类 | 4437篇 |
化学工业 | 12350篇 |
金属工艺 | 3940篇 |
机械仪表 | 4813篇 |
建筑科学 | 5239篇 |
矿业工程 | 2399篇 |
能源动力 | 2244篇 |
轻工业 | 4778篇 |
水利工程 | 1010篇 |
石油天然气 | 5282篇 |
武器工业 | 470篇 |
无线电 | 7605篇 |
一般工业技术 | 9380篇 |
冶金工业 | 3779篇 |
原子能技术 | 743篇 |
自动化技术 | 8704篇 |
出版年
2024年 | 142篇 |
2023年 | 1207篇 |
2022年 | 1743篇 |
2021年 | 2831篇 |
2020年 | 2182篇 |
2019年 | 1931篇 |
2018年 | 2276篇 |
2017年 | 2502篇 |
2016年 | 2083篇 |
2015年 | 2733篇 |
2014年 | 3464篇 |
2013年 | 4253篇 |
2012年 | 4393篇 |
2011年 | 4891篇 |
2010年 | 4198篇 |
2009年 | 3972篇 |
2008年 | 3873篇 |
2007年 | 3734篇 |
2006年 | 3819篇 |
2005年 | 3447篇 |
2004年 | 2292篇 |
2003年 | 2087篇 |
2002年 | 1875篇 |
2001年 | 1640篇 |
2000年 | 1809篇 |
1999年 | 2044篇 |
1998年 | 1759篇 |
1997年 | 1406篇 |
1996年 | 1385篇 |
1995年 | 1175篇 |
1994年 | 939篇 |
1993年 | 708篇 |
1992年 | 539篇 |
1991年 | 420篇 |
1990年 | 324篇 |
1989年 | 248篇 |
1988年 | 219篇 |
1987年 | 138篇 |
1986年 | 101篇 |
1985年 | 89篇 |
1984年 | 59篇 |
1983年 | 34篇 |
1982年 | 42篇 |
1981年 | 28篇 |
1980年 | 22篇 |
1979年 | 14篇 |
1977年 | 7篇 |
1976年 | 8篇 |
1975年 | 5篇 |
1945年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 682 毫秒
51.
52.
针对矿山18线南西翼矿体开采过程中存在的通风系统不完善、风量欠缺、污风无法及时排出等问题,运用风压平衡原理、网络优化技术、机站优化技术以及计算机网络模拟技术展开研究,拟定了3种可行的通风方案。经技术经济比较,确定了新掘18线905~855 m回风井(1.5 m),保留该井905 m 水平回风机站,并在855 m 水平新设1台K45 6 №12风机(18.5 kW)方案。数值模拟结果表明:18线南西翼通风系统总风量达到20.5 m3/s,井下风流的可调性和稳定性增强,为矿山的安全生产提供了有力保障。 相似文献
53.
54.
Binbo Jiang Jincheng Dai Jingyuan Sun Jian Ye Meijuan Chen Guodong Han Jingdai Wang Jian Yang Yongrong Yang 《Polymer Engineering and Science》2020,60(8):1998-2007
The diffusion behavior of ethylene in polyethylene is of great importance for the polymerization and degassing of polyethylene (PE) industry. Based on the gravimetric sorption and desorption measurement approach, an intelligent gravimetric analyzer is applied to obtain the solubility and diffusion coefficients of ethylene in solid low-density PE (LDPE) with different melt indices at 30°C to 70°C, 0 to 4 atm and in molten LDPE at 160°C to 230°C, 0 to 4 atm, respectively. Results indicate that both the solubility and diffusion coefficients of ethylene in solid LDPE are smaller than those in molten LDPE, while the dissolution enthalpy and diffusion activation energy of ethylene in solid LDPE are higher. In addition, one- and two-dimensional diffusion models are built and the effects of particle size, polymer properties, and operation conditions are systematically investigated on the diffusion behaviors of ethylene in solid and molten LDPE. 相似文献
55.
57.
Anti-washout and tissue adhesion properties are essential for the clinical application of injectable bone materials. In this study, we prepared calcium phosphate cement (CPC) with anti-washout and tissue adhesion properties and attempted to build covalent bonds between CPC and the amino groups in bone tissue under a self-regulating pH system in the CPC (acidic to basic). The results of push-out tests demonstrated that a significant enhancement (from 6.42 ± 0.76 N to 61.5 ± 4.09 N) in tissue adhesion was obtained with the addition of 6% (w/w) oxidized sodium alginate (OSA) in CPC. The FTIR, XRD, anti-washout test, XPS, pH test, and SEM results suggested that the synergistic effect of OSA-citric acid (CA) led to the formation of a three-dimensional gel network structure in the CPC, and the Schiff base reaction between aldehyde and amino groups induced adhesion between CPC and the bone tissue. Further, the addition of less OSA had no significant negative effect on the hydration properties of CPC. Our work aims to promote the development of injectable bone material in clinical applications. 相似文献
58.
Zhang Xi Wang Xianhai Zhao Hongke Ordóñez de Pablos Patricia Sun Yongqiang Xiong Hui 《Scientometrics》2019,119(3):1311-1344
Scientometrics - Altmetrics indices are increasingly applied to measure scholarly influence in recent years because they can reflect the influence of research outputs more timely comparing with... 相似文献
59.
This paper presents a spatio-temporal fusion method for remote sensing images by using a linear injection model and local neighbourhood information. In this method, the linear injection model is first introduced to generate an initial fused image, the spatial details are extracted from the fine-resolution image at the base date, and are weighted by a proper injection gains. Then, the spatial details and the relative spectral information from the coarse-resolution images are blended to generate the fusion result. To further enhance its robustness to the noise, the local neighbourhood information, derived from the fine-resolution image and the fused result simultaneously, is introduced to refine the initial fused image to obtain a more accurate prediction result. The algorithm can effectively capture phenology change or land-cover-type change with minimum input data. Simulated data and two types of real satellite images with seasonal changes and land-cover-type changes are employed to test the performance of the proposed method. Compared with a spatial and temporal adaptive reflectance fusion model (STARFM) and a flexible spatio-temporal fusion algorithm (FSDAF), results show that the proposed approach improves the accuracy of fused images in phenology change area and effectively captures land-cover-type reflectance changes. 相似文献
60.
Yuhuan Sun Hongshuang Qin Zhengqing Yan Chuanqi Zhao Jinsong Ren Xiaogang Qu 《Advanced functional materials》2019,29(14)
Recently, quorum sensing (QS) inhibitors (QSIs) have been combined with antibiotics to enhance antibiofilm efficacy in vitro and in vivo. However, targeting QS signals alone is not enough to prevent bacterial infections. Drug resistance and recurrence of biofilms makes it difficult to eradicate. Herein, photodynamic therapy (PDT) is selected to unite QSIs and antibiotics. A synergistically antibiofilm system, which combines QSIs, antibiotics, and PDT based on hollow carbon nitride spheres (HCNSs) is envisaged. First, HCNS provides the multidrug delivering ability, enabling QSIs and antibiotics to be released in sequence. Subsequently, multistage releases sensitize bacteria effectively, potentiating the chemotherapeutic effects of the antibiotics. Finally, the integration of QSIs and PDT not only minimizes the possibility of drug resistance, but also overcomes the problem of limited mass and extension of PDT. Even after 48 h of incubation, the bacterial biofilm is obviously inhibited. And its biofilm disperse efficiency exceeds 48% (compared with QSI‐potentiated chemotherapy group) and 40% (compared with PDT group). Besides, the inhibition of the QS system influences phenotypes related to virulence factor production and surface hydrophobicity, which weaken biofilm invasion and formation. Eventually, this system is applied to disperse bacterial biofilm in vivo. Overall, PDT and QS modulation are devoted to eradicate drug resistance and recurrence of the biofilm. 相似文献