全文获取类型
收费全文 | 371篇 |
免费 | 12篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 14篇 |
综合类 | 1篇 |
化学工业 | 139篇 |
金属工艺 | 7篇 |
机械仪表 | 8篇 |
建筑科学 | 4篇 |
能源动力 | 28篇 |
轻工业 | 32篇 |
无线电 | 23篇 |
一般工业技术 | 80篇 |
冶金工业 | 7篇 |
原子能技术 | 7篇 |
自动化技术 | 35篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 9篇 |
2021年 | 9篇 |
2020年 | 4篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 5篇 |
2016年 | 13篇 |
2015年 | 7篇 |
2014年 | 17篇 |
2013年 | 21篇 |
2012年 | 22篇 |
2011年 | 25篇 |
2010年 | 20篇 |
2009年 | 31篇 |
2008年 | 25篇 |
2007年 | 20篇 |
2006年 | 13篇 |
2005年 | 18篇 |
2004年 | 15篇 |
2003年 | 18篇 |
2002年 | 13篇 |
2001年 | 9篇 |
2000年 | 10篇 |
1999年 | 5篇 |
1998年 | 7篇 |
1997年 | 1篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有385条查询结果,搜索用时 15 毫秒
101.
Takahashi M Iwakiri K Sotoyama M Higuchi S Kiguchi M Hirata M Hisanaga N Kitahara T Taoda K Nishiyama K 《Applied ergonomics》2008,39(5):597-604
Nursing home caregivers (n=775; 604 women; mean age 33.6 years) were studied to examine how work schedules affect their sleep. The shift group (n=536) worked under a rotating two-shift system (n=365), a rotating three-shift system (n=66), or other types of shifts (n=78). The non-shift group included 222 caregivers. Participants completed a questionnaire about working conditions, sleep problems, health, lifestyle, and demographic factors. The two-shift caregivers reported the highest levels of difficulty initiating sleep (DIS, 37.6%), insomnia symptoms (43.0%), and poor quality of sleep (24.9%) among the groups. Adjusted odds ratios for these problems were significantly greater for the two-shift caregivers than for non-shift counterparts: DIS (odds ratio 2.86, 95% confidence interval 1.57-5.20), insomnia symptoms (2.33, 1.36-4.02), and poor sleep quality (2.15, 1.09-4.22). Our data suggest that working under a rotating two-shift system, which has a longer night shift, is associated with an elevated risk of sleep problems for nursing home caregivers. 相似文献
102.
Shunsuke Kobayashi Brindaban Kundu Tomohiro Miyama Yukihide Shiraishi Hiroya Sawai Naoki Toshima Masaya Okita Kiyofumi Takeuchi Haruyoshi Takatsu 《Journal of the Society for Information Display》2011,19(11):787-792
Abstract— The fabrication and demonstration of field‐sequential‐color (FSC) LCDs using modules of narrow‐gap twisted‐nematic (NTN) LCDs with and without doping of newly synthesized PγCyD‐ZrO2 nanoparticles is reported. Two types of FSC‐LCDs are demonstrated: one is a direct multiplexed NTN‐LCD and the other is TFT driven. The advantages of FSC‐LCDs include their high legibility even under direct sunlight, and the mechanism for the doping of nanoparticles in LCDs is discussed. 相似文献
103.
Masaya Nakayama Atsushi Sato Kazuaki Ishihara Hisashi Yamamoto 《Advanced Synthesis \u0026amp; Catalysis》2004,346(11):1275-1279
ZrOCl2⋅8 H2O and HfOCl2⋅8 H2O are highly effective, water‐tolerant, and reusable homogeneous catalysts for direct ester condensation between equimolar amounts of carboxylic acids and alcohols. Notably, zirconium(IV) salts such as ZrOCl2⋅8 H2O and Zr(OAc)x(OH)y are potential green catalysts due to their low toxicity, commercial availability at low cost, ease of handling, high catalytic activity, and reusability. 相似文献
104.
Tatsuhiro Okada Satoshi Gotou Masaya Yoshida Makoto Yuasa Takuji Hirose Isao Sekine 《Journal of Inorganic and Organometallic Polymers》1999,9(4):199-219
Reduction of platinum catalysts loading is a central issue in polymer electrolyte fuel cells. As alternatives for platinum, some organic metal chelate compounds are tested as cathode catalysts, such as cobalt aza-complexes or cobalt complexes possessing aminophenyl moieties featured as Co-N4 or Co-N2O2 chelate structures. The way of immobilization of catalysts on the graphite surface influences their stability as well as the performance of oxygen reduction. Heat-treated catalysts supported on graphite at 600°C show much better oxygen reduction abilities than as-received metal complexes. The original chemical structure of metal complexes affects crucially the catalytic ability, though initial structures of molecules are no more intact after the heat treatment. The catalytic activity of these complexes may originate from the central chelate unit CoN4 on the carbon substrate, and this unit is assumed to constitute the basic coordination site for an oxygen molecule. Electropolymerized catalysts impart a high level of oxygen reduction ability, probably due to the improved molecular orientation for oxygen coordination and formation of good chelate sites on the graphite surface. 相似文献
105.
Endosperm starch isolated from an amylose‐free waxy mutant hull‐less barley line, Shikoku Hadaka 97, had an amylose content of 0.3% and higher swelling power than ordinary waxy barley cultivars/lines with amylose contents of 2.2—6.5%. A highly significant correlation was observed between amylose content and swelling power among waxy barley starches. No clear differences were detected in the chain‐length distribution profiles or thermal properties between the amylose‐free starch and ordinary waxy starch. The chain‐length distribution profile of waxy barley starch was slightly different from that of normal barley starch. Gelatinization temperatures and gelatinization enthalpy of waxy barley starch were higher than those of normal barley starch. Significant correlations were observed between amylose content and thermal properties of starch samples analyzed. Waxy barley starch stained with a concentrated iodine‐potassium iodide solution showed a ghost‐like appearance. 相似文献
106.
Kentaro Teramura Tsunehiro Tanaka Tomohiro Hosokawa Tai Ohuchi Masaya Kani Takuzo Funabiki 《Catalysis Today》2004,96(4):205-209
More than 0.22 mmol of isolated VO4 species of V2O5/Al2O3 exhibited the highest evolution of the partial oxidation products (alcohol and ketone) in the oxidation of cyclohexane and cyclopentane. The conversion of cyclohexane and the selectivity of the partial oxidation products were achieved to be 0.49% and 85% over 0.8 g of 3.5 wt.% V2O5/Al2O3, respectively, where the K/A ratio was 6.2. In addition, V2O5/Al2O3 can selectively oxidize various hydrocarbons in the liquid phase by the one-step oxygen atom insertion to CH bond. The order of priority was tertiary carbon > secondary carbon > primary carbon > benzene ring. 相似文献
107.
A new strategy for directly fabricating fine gold patterns from an aqueous solution with the help of a UV laser is proposed.
The solution contains 90 mmol/L of HAuCl4 and 280 mmol/L of Na2SO3. The process involves two steps. The first step is to create the pattern (seed layer) by irradiating the solution layer spread
on the substrate by the UV laser beam. The second step is to immerse the patterned or irradiated substrate in the bulk solution
for a certain time to grow the film. A 0.1-μm-thick film is yielded in the irradiated area after 30 min immersion in the solution. 相似文献
108.
109.
The mechanism of the liquid phase methanol reforming reaction over silica supported Pt–Ru catalyst was investigated by kinetic studies, employing a pyrex glass reactor with reflux condensers connected to a closed gas circulation system under ambient pressure. The rate of H2 formation over Pt–Ru/SiO2 catalysts was more than 20 times faster than that over Pt/SiO2 catalysts with high selectivity for CO2 (72.3%), indicating a marked addition effect of Ru. In the case of HCHO–H2O reaction over Pt–Ru/SiO2, the H2 formation rate was five times larger than that in the CH3OH–H2O reaction but selectivity to CO2 was only 4%. On the contrary, in the HCOOCH3–H2O and HCOOH–H2O reactions, both high activity and selectivity were observed over Pt–Ru/SiO2. These results clearly indicate that the CO2 formation does not proceed via HCHO decomposition and following water gas shift reaction. We propose the following pathway for liquid phase methanol reforming reaction over Pt–Ru/SiO2; a partly dehydrogenated methanol (CH2OH*) is the initial reaction intermediate, from which H2 and CO2 are formed through HCOOCH3 and HCOOH as the successive reaction intermediates. 相似文献
110.