全文获取类型
收费全文 | 2372篇 |
免费 | 238篇 |
国内免费 | 44篇 |
专业分类
电工技术 | 11篇 |
综合类 | 61篇 |
化学工业 | 345篇 |
金属工艺 | 28篇 |
机械仪表 | 27篇 |
建筑科学 | 56篇 |
矿业工程 | 24篇 |
能源动力 | 118篇 |
轻工业 | 1511篇 |
水利工程 | 20篇 |
石油天然气 | 27篇 |
无线电 | 39篇 |
一般工业技术 | 102篇 |
冶金工业 | 20篇 |
原子能技术 | 9篇 |
自动化技术 | 256篇 |
出版年
2024年 | 26篇 |
2023年 | 87篇 |
2022年 | 136篇 |
2021年 | 166篇 |
2020年 | 161篇 |
2019年 | 175篇 |
2018年 | 97篇 |
2017年 | 107篇 |
2016年 | 122篇 |
2015年 | 169篇 |
2014年 | 146篇 |
2013年 | 143篇 |
2012年 | 213篇 |
2011年 | 196篇 |
2010年 | 140篇 |
2009年 | 100篇 |
2008年 | 57篇 |
2007年 | 115篇 |
2006年 | 109篇 |
2005年 | 34篇 |
2004年 | 14篇 |
2003年 | 8篇 |
2002年 | 21篇 |
2001年 | 12篇 |
2000年 | 11篇 |
1999年 | 6篇 |
1998年 | 11篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 9篇 |
1987年 | 15篇 |
1986年 | 12篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1959年 | 1篇 |
排序方式: 共有2654条查询结果,搜索用时 15 毫秒
1.
《Ceramics International》2019,45(15):18972-18979
Kaolin/graphene oxide composite has been widely utilized in aero-space and architectural engineering applications due to its excellent mechanical property. Direct ink writing (DIW) is a freeform rapid prototyping technology that could be used to accurately fabricate the resulting size with complex shapes. In this study, we reported the DIW of kaolin/graphene oxide (GO) composite suspensions (KGCS) to assemble 3D structures at ambient temperature for the first time. The effects of GO on the chemical constitution and microstructure of kaolin suspensions were investigated. Rheology was characterized to ensure printability of KGCS. The addition of GO in kaolin suspensions quickened a flocculation structure, which dramatically changed their rheology properties. The DIW of 3D structures from the optimal KGCS sample maintained their initial shape without spreading. The flexural and compressive strengths of the dried optimal KGCS samples were obviously enhanced due to the improvement and reduction of the micro-defects compared from cured kaolin matrix. 相似文献
2.
Polyimide/titania (PI/TiO2) nanocomposite films have been successfully fabricated through the in situ formation of TiO2 within a PI matrix via sol–gel method. Poly(amic acid) (PAA), which is the precursor of PI, was successfully synthesized by mixing pyromellitic dianhydride (PMDA), with equimolar amount of a diamine monomer having a pendent benzoxazole unit and two flexible ether linkages in N,N-dimethylformamide (DMF) solvent. Tetraethyl orthotitanate [Ti(OEt)4] and acetylacetone were then added to the resulted PAA. After imidization at high temperature, PI/TiO2 hybrid films were formed. The structure and morphology of the hybrid nanocomposites with different titania contents (0 wt%, 5 wt%, 10 wt%, and 15 wt%) were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and transmission electron microscopy. The results indicate that the TiO2 nanoparticles were homogeneously dispersed in the hybrid films. The thermogravimetric analysis of nanocomposites confirms the improvement in the thermal stability with the increase in the percentage of titania nanoparticle. Transmission electron microscopy showed that the nanoparticles with an average diameter of 25–40 nm were dispersed in the polymer matrix. 相似文献
3.
Rice straw is the most abundant agricultural residue on a global scale and is widely available as feedstock for cellulosic fuel production. However, it is highly recalcitrant to biochemical deconstruction and also generates inhibitors that affect enzymatic saccharification. Rice straw from eastern Arkansas was subjected to dilute acid pretreatment (160 °C, 48 min and 1.0% sulfuric acid) and solid-state fermentation with two lignocellulolytic fungi, Trametes hirsuta and Myrothecium roridum, and their saccharification efficacies were compared. T. hirsuta and M. roridum were tested separately; pretreatment of rice straw with either strain for seven days resulted in 19 and 70% enrichment of its holocellulose content, respectively. However, liquid chromatography analysis of the alkali extracts showed significant differences in cell wall degradation by T. hirsuta and M. roridum. T. hirsuta removed 15% more phenolic compounds and 38% more glucan than M. roridum, while M. roridum removed 77% more xylan than T. hirsuta. Fungal and dilute acid pretreated biomass was then hydrolyzed using Accellerase® 1500, a saccharification cocktail. Saccharification efficiency of M. roridum was 37% higher than that of dilute acid pretreatment of rice straw, requiring 8% lower enzyme loading and 50% shorter enzymatic hydrolysis duration. Alkali extraction of fungal pretreated biomass also yielded 10–15 g kg−1 of acid precipitable polymeric lignin (APPL), which is a valuable co-product for biorefineries. In comparison to dilute acid pretreatment, fungal pretreatment could be a cost-effective alternative for the degradation of recalcitrant biomass, such as rice straw. 相似文献
4.
5.
《Materials Letters》2007,61(8-9):1881-1884
Organic ultraviolet (UV) ray absorbents, cinnamic acid (CA) and p-methoxycinnamic acid (PMOCA) were intercalated into Zn2Al layered double hydroxides (Zn2Al-LDHs) by co-precipitation reaction. The organic–inorganic nanocomposites, Zn2Al-LDH/CA and Zn2Al-LDH/PMOCA were obtained. The samples showed excellent UV ray absorption ability and their catalytic activity for the air oxidation of castor oil greatly decreased when the organic UV ray absorbents were intercalated in the layers of the Zn2Al-LDHs. The studies suggested that Zn2Al-LDH/organic UV absorbent nanocomposites might be used as safe sunscreen materials. 相似文献
6.
7.
Perceptual scenes and scene swing surveys are the ideas for reminding local and wooded area park executives and scene placement. The maximum precise analysis of panorama visualization, forest park landscapes, planning of essential scenic spots, and visualization and safety of Geographic Information Systems (GIS) cost tools is primarily based on management and historical data. Visual impacts and cultural, historical past adjustments to are expecting visual and natural landscapes. By deciding on points from a panorama attitude, intervention calls for vital signs and symptoms of safety. Among them, studies are being carried out in many towns around the arena. Geographic Information System (GIS) depends simply on noticeable assessment and is remembered for the social legacy plan. The Gate Array (FPGA) and Geographic Information System (GIS) are analyzed based on the panorama in every place within the painting's framework. In these activities, landscape planning is proposed thru the development of scientific Piedmont. Turin is conducting a few research. From a global attitude, the version suggests that these packages reduce the capability use of the era. 相似文献
8.
9.
The paper proposes several mathematical models of the multidirectional associative memory (MAM) neural network by analyzing
its structure. A model of MAM with distributed delays is studied. Under some new assumptions on activation functions, 2n0[m/2]{2^{n_0[m/2]}} invariant subsets of MAM are constructed. Then the existence and the exponential stability of 2n0[m/2]{2^{n_0[m/2]}} periodic solutions located on invariant subsets are obtained by constructing a suitable Liapunov function and a Poincaré
mapping. An estimating method of the exponential convergence rate is given. The obtained results are new to MAM neural networks.
An example is given to illustrate the effectiveness of the results. 相似文献
10.
基于视觉的疲劳驾驶检测技术是疲劳检测领域的前沿技术。根据基于视觉的车载驾驶员疲劳检测系统实时、小型化、非接触、可扩展等技术要求,以ARM开发板和嵌入式Linux操作系统为平台,设计了一套基于PERCLOS疲劳驾驶检测方法,与传统的基于PC机的疲劳检测系统相比,具有更好的稳定性、可行性以及更优越的可扩充性。 相似文献