全文获取类型
收费全文 | 655篇 |
免费 | 11篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 17篇 |
化学工业 | 123篇 |
金属工艺 | 20篇 |
机械仪表 | 7篇 |
建筑科学 | 21篇 |
能源动力 | 21篇 |
轻工业 | 69篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 43篇 |
一般工业技术 | 111篇 |
冶金工业 | 180篇 |
原子能技术 | 10篇 |
自动化技术 | 43篇 |
出版年
2023年 | 7篇 |
2022年 | 5篇 |
2021年 | 15篇 |
2020年 | 11篇 |
2019年 | 11篇 |
2018年 | 6篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 9篇 |
2014年 | 13篇 |
2013年 | 26篇 |
2012年 | 21篇 |
2011年 | 31篇 |
2010年 | 16篇 |
2009年 | 34篇 |
2008年 | 20篇 |
2007年 | 14篇 |
2006年 | 11篇 |
2005年 | 18篇 |
2004年 | 18篇 |
2003年 | 12篇 |
2002年 | 15篇 |
2001年 | 11篇 |
2000年 | 12篇 |
1999年 | 14篇 |
1998年 | 75篇 |
1997年 | 40篇 |
1996年 | 28篇 |
1995年 | 14篇 |
1994年 | 13篇 |
1993年 | 16篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1970年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有667条查询结果,搜索用时 0 毫秒
121.
This study investigated whether the disengagement of attention from facial expression is modulated by gaze direction in infants. To this end, we measured the saccadic reaction time required for the 10-month-olds to disengage their attention from angry and happy expressions combined with either straight or averted gaze. The 10-month-olds' disengagement of their attention from happy faces was modulated by gaze direction. This finding indicates that gaze direction strongly influences infants' allocation of attention to facial expressions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
122.
123.
Nano-sized LiMn2O4 particles were prepared at 1023 K by electrospray pyrolysis in which they were directly deposited on a Pt substrate in gas phase. Cyclic voltammetry gave very sharp and symmetrical redox peaks at ca. 4.0 and 4.1 V vs. Li/Li+ owing to the insertion and extraction of lithium-ion at LiMn2O4. However, the redox peaks broadened and their peak separation in an electrode potential increased when aggregated nano-sized LiMn2O4 particles were used. In Nyquist plots, a semi-circle due to lithium-ion transfer resistance appeared at potentials above 3.90 V. The values of the lithium-ion transfer resistances were small for dispersed nano-sized LiMn2O4 particles. On the other hand, the lithium-ion transfer resistances increased and the Warburg impedance became obvious as the nano-sized LiMn2O4 particles aggregated. These results clearly indicate that the apparent rapid diffusion of lithium-ion can be attained using well-dispersed nano-sized particles of electroactive materials. 相似文献
124.
Takayuki Doi Masao Tagashira Yasutoshi Iriyama Takeshi Abe Zempachi Ogumi 《Journal of Applied Electrochemistry》2012,42(2):69-74
SiO2–non-graphitizable carbon composites were prepared by pyrolysis of a mixture of ethyl cellulose and nano-sized SiO2. The composite electrode showed high reversibility in insertion and/or extraction reactions of Li ions at potentials below
1 V with little hysteresis after the 2nd cycle, whereas a large irreversible capacity was observed in the 1st cycle. This
reversible capacity increased with increasing SiO2 content above 5 wt%. Li ion transfer at the interface between a composite electrode and an electrolyte was studied by ac
impedance spectroscopy. In the Nyquist plots, a semi-circle that was assigned to charge-transfer resistance (R
ct) because of Li ion transfer across the interface between the composite electrode and electrolyte appeared at potentials below
1 V. The values of R
ct decreased with increasing SiO2 content. These results indicate that both a decrease in R
ct and an increase in reversible capacity can be achieved by use of SiO2–non-graphitizable carbon composite electrodes; this would lead to Li-ion batteries with higher power and energy density. 相似文献
125.
Koyanagi S Hamasaki H Sekiguchi S Hara K Ishii Y Kyuwa S Yoshikawa Y 《Reproduction (Cambridge, England)》2012,143(3):271-279
Maternal proteins are rapidly degraded by the ubiquitin-proteasome system during oocyte maturation in mice. Ubiquitin C-terminal hydrolase L1 (UCHL1) is highly and specifically expressed in mouse ova and is involved in the polyspermy block. However, the role of UCHL1 in the underlying mechanism of polyspermy block is poorly understood. To address this issue, we performed a comprehensive proteomic analysis to identify maternal proteins that were relevant to the role of UCHL1 in mouse ova using UCHL1-deficient gad. Furthermore, we assessed morphological features in gad mouse ova using transmission electron microscopy. NACHT, LRR, and PYD domain-containing (NALP) family proteins and endoplasmic reticulum (ER) chaperones were identified by proteomic analysis. We also found that the 'maternal antigen that embryos require' (NLRP5 (MATER)) protein level increased significantly in gad mouse ova compared with that in wild-type mice. In an ultrastructural study, gad mouse ova contained less ER in the cortex than in wild-type mice. These results provide new insights into the role of UCHL1 in the mechanism of polyspermy block in mouse ova. 相似文献
126.
127.
Suzuki S Teshima K Lee S Yubuta K Ishizaki T Shishido T Oishi S 《Journal of nanoscience and nanotechnology》2011,11(7):6335-6340
Carbon nanotubes (CNTs) are promising catalyst supports for fuel cell applications. Metal oxide/CNT nanocomposites are also being studied for dye-sensitized solar-cell, photocatalyst, and sensor applications. The fabrication of nanocomposites consisting of highly crystalline NbOx nanotubes and cup-stacked carbon nanotubes (CSCNTs) is reported herein. The CSCNTs were selected for the carbon materials because of their distinctive structure. The CSCNTs were photochemically treated with vacuum ultraviolet light, which increased the amount of oxygen-containing functional groups therein. NbOx nanotubes with no defects were successfully prepared with the chemical treatment of highly crystalline, layered, flux-grown K4Nb6O17 crystals. First, K4Nb6O17 crystals were grown from a KCl flux at a holding temperature of 800 degrees C. Next, NbOx nanosheets were prepared from the layered K4Nb6O17 crystals via a two-step exfoliation process, which consists of proton exchange in an acid solution and intercalation of the tetrabutylammonium ions. The NbOx nanosheets were rolled up into nanotubes with diameters of about 20 nm and lengths of 100-500 nm on the surfaces of the CSCNTs; thus, unique and complex NbOx/CSCNT nanocomposites were successfully fabricated. 相似文献
128.
129.
130.
Shirouchi B Kawamura S Matsuoka R Baba S Nagata K Shiratake S Tomoyori H Imaizumi K Sato M 《Lipids》2011,46(8):789-793
Guar gum has a well-recognized hypolipidemic effect. This effect is thought to be due to the physicochemical properties of
guar gum, which may cause changes in adsorption of lipids or the viscosity of the intestinal contents. Guar gum is a non-specific
absorption inhibitor of any type of lipid-soluble compound. Permanent lymph duct cannulation was performed on rats to investigate
the effects of dietary guar gum on lymph flow and lipid transport. Rats fed a 5% guar gum diet were compared with those fed
a 5% cellulose diet, and lymph was collected after feeding. The water-holding capacity (WHC), settling volume in water (SV),
and viscosity of guar gum were compared with those of cellulose. Rats fed with the guar gum diet had significantly lower lymph
flow and lymphatic lipid transport than did rats fed with the cellulose diet. The WHC, SV, and viscosity of guar gum were
significantly higher than those of cellulose. We propose that dietary guar gum reduces lymph flow and thereby diminishes lipid
transport by means of its physicochemical properties related to water behavior in the intestine. 相似文献