全文获取类型
收费全文 | 97015篇 |
免费 | 10660篇 |
国内免费 | 6484篇 |
专业分类
电工技术 | 8061篇 |
综合类 | 9324篇 |
化学工业 | 12301篇 |
金属工艺 | 6023篇 |
机械仪表 | 5959篇 |
建筑科学 | 6146篇 |
矿业工程 | 3745篇 |
能源动力 | 2836篇 |
轻工业 | 10779篇 |
水利工程 | 3081篇 |
石油天然气 | 2991篇 |
武器工业 | 1565篇 |
无线电 | 8427篇 |
一般工业技术 | 7775篇 |
冶金工业 | 11158篇 |
原子能技术 | 1509篇 |
自动化技术 | 12479篇 |
出版年
2024年 | 489篇 |
2023年 | 1573篇 |
2022年 | 3851篇 |
2021年 | 4902篇 |
2020年 | 3499篇 |
2019年 | 2486篇 |
2018年 | 2724篇 |
2017年 | 2830篇 |
2016年 | 2675篇 |
2015年 | 4058篇 |
2014年 | 5121篇 |
2013年 | 6245篇 |
2012年 | 7553篇 |
2011年 | 7798篇 |
2010年 | 7465篇 |
2009年 | 6801篇 |
2008年 | 6844篇 |
2007年 | 6634篇 |
2006年 | 5683篇 |
2005年 | 4386篇 |
2004年 | 3256篇 |
2003年 | 2232篇 |
2002年 | 1972篇 |
2001年 | 1811篇 |
2000年 | 1475篇 |
1999年 | 777篇 |
1998年 | 2790篇 |
1997年 | 1616篇 |
1996年 | 1040篇 |
1995年 | 634篇 |
1994年 | 510篇 |
1993年 | 573篇 |
1992年 | 139篇 |
1991年 | 141篇 |
1990年 | 142篇 |
1989年 | 136篇 |
1988年 | 107篇 |
1987年 | 111篇 |
1986年 | 105篇 |
1985年 | 75篇 |
1984年 | 37篇 |
1983年 | 43篇 |
1982年 | 55篇 |
1981年 | 49篇 |
1980年 | 86篇 |
1979年 | 30篇 |
1978年 | 24篇 |
1977年 | 169篇 |
1976年 | 297篇 |
1959年 | 36篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
2.
3.
4.
Salehe Gomroki Zahra Yavari Ahmad Reza Abbasian Meissam Noroozifar 《International Journal of Applied Ceramic Technology》2021,18(6):2099-2110
The spongy nickel oxide (SNO) was synthesized the solution combustion method. The SNO was selected as a promoter to boost the catalytic activity of nanoraspberry-like palladium (NRPd) toward electrooxidation of five light fuels (LFs): methanol, ethanol, formaldehyde, formic acid, and ethylene glycol. The X-ray powder diffraction, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy, and field emission scanning electron microscope techniques were used for the materials characterization. In comparison with nonpromoted Pd, the NRPd-SNO electrocatalyst shown an excellent efficiency in parameters like the electrochemical active surface area and anti-CO poisoning behavior. The turnover data and the parameters, including reaction order, activation energy, and the coefficients of electron transfer and diffusion, were evaluated for the each process of LFs electrooxidation. The outcome for NRPd-SNO activity toward LFs electrooxidation was compared to some reported electrodes. The SNO increases the removal of intermediates created in the oxidation of LFs that can poison the surface of palladium catalyst. This is due to the presence of the lattice oxygens in SNO structure and Ni switching between its high and low valances. The compatibility of the adsorption process of LFs on the surface of the NRPd-SNO catalyst with different isotherms was determined by studying the Tafel polarization and calculating the surface coverage. 相似文献
5.
乡村产业中的化石能源设备逐渐被电能技术替代,引起了乡村负荷波动增大、部分时段产生集中高负荷的问题。为了解决以上问题,将低品位清洁能源应用至乡村的茶叶生产中,针对烘茶全过程的工艺要求提出了跨临界CO2热泵烘茶技术;并以某茶叶生产乡村为对象,对其代表台区的全年日用电量及产茶日负荷进行了分析,得出采用CO2热泵烘茶后其负荷得到大幅度削减,整体可降低至原负荷的39.6%~46.8%,峰值负荷与平时负荷的比值由原本的13.6降至5.4~6.2。跨临界CO2热泵应用至农产品生产中可有效缓解乡村供电压力。 相似文献
6.
Ahmad Zamani Gharaghooshi Akbarinezhad Esmaeil Esmaeili Naser Neshati Jaber 《Protection of Metals and Physical Chemistry of Surfaces》2021,57(1):153-167
Protection of Metals and Physical Chemistry of Surfaces - In this study, the inhibitive performance of 2-mercaptobenzothiazole (2MBT) and 2-aminobenzothiazole (2ABT) were investigated on API-5L X60... 相似文献
7.
以蚕丝蛋白为模板,在相对温和的条件下通过生物矿化的手段形成具有特殊形貌的α-GaOOH颗粒,并通过在不同温度下煅烧α-GaOOH得到α-Ga2O3和β-Ga2O3.采用扫描电镜(SEM)、透射电镜(TEM)、X射线衍射仪(XRD)和荧光分光光度计(PL)等手段研究了丝素蛋白多肽和矿化时间对颗粒的影响,对其生物矿化机理进行了初步探讨.结果表明,所制备的β-Ga2O3具有优良的发光特性,丝素蛋白多肽模板以无定形的结构与产物结合在一起,并且经过高温烧结后仍以碳膜的形式包覆在材料的表面.这种碳膜结构对于提高材料的生物学性能起着重要的作用. 相似文献
8.
Solomon Hanson Duntu Francis Tetteh Iftikhar Ahmad Mohammad Islam Solomon Boakye-Yiadom 《Ceramics International》2021,47(1):367-380
The onset of hybrid alumina-based composites, which combines two or more nano-particles within the alumina matrix has already shown promising improvements in the matrix material. However, variations in mechanical properties including the optimum compositions that give improved properties faced with the development of alumina-based composites require further studies to understand the underlying mechanisms and synergistic effects of the nano-particle additions on the alumina matrix. In the current study, the structure and properties of Al?O?-graphene (0.5 wt%) and Al?O?–ZrO? (4 wt% and 10 wt%) composites fabricated via hot-pressing was studied as a baseline for multiple combinations. Even though the addition of 10 wt%ZrO? resulted in a 23% reduction in the grain size of the alumina matrix, the 4 wt%ZrO? addition resulted in a 14% increase in grain size as compared to the parent alumina matrix. X-ray diffraction analysis revealed that there was approximately 85% monoclinic (m-ZrO2) vs. 15% tetragonal (t-ZrO2) crystal structures in the A4ZrO? sample whilst the A10ZrO? had approximately 93% m-ZrO2 vs. 7% t-ZrO2. The high-volume fraction of the monoclinic crystal structures in the A10ZrO? accounts for the induced microcracks in the sample since the transition from the ductile-tetragonal to brittle-monoclinic is associated with the exertion of compressive stresses on the alumina matrix by the associated elastic volume expansion of m-ZrO2. Also, the addition of 0.5 wt%graphene resulted in about 37% reduction in the grain size of the alumina matrix, and approximately 10% increase in hardness as a result of the distribution of graphene along the grain boundaries of the parent alumina matrix, which restricts grain coalescence and growth during processing. Furthermore, an increase up to 115% and 164% were observed in the fracture toughness (KIC) with the inclusion of 0.5 wt%graphene and 10 wt%ZrO? respectively, which was primarily ascribed to the fine-grained microstructures and toughening mechanisms of the intergranular graphene and ZrO? particles. 相似文献
9.
Malik Lateef Ahmad Pandith Altaf Hussain Bashir Arshid Qureashi Aaliya 《Journal of Materials Science: Materials in Electronics》2022,33(9):6178-6189
Journal of Materials Science: Materials in Electronics - Multiwalled carbon nanotubes, due to high conductivity, stability, and large specific surface area, have a potential ability to promote... 相似文献
10.