全文获取类型
收费全文 | 562篇 |
免费 | 62篇 |
国内免费 | 3篇 |
专业分类
化学工业 | 194篇 |
金属工艺 | 3篇 |
机械仪表 | 27篇 |
建筑科学 | 16篇 |
矿业工程 | 3篇 |
能源动力 | 13篇 |
轻工业 | 203篇 |
水利工程 | 4篇 |
石油天然气 | 6篇 |
无线电 | 14篇 |
一般工业技术 | 67篇 |
冶金工业 | 27篇 |
原子能技术 | 1篇 |
自动化技术 | 49篇 |
出版年
2024年 | 3篇 |
2023年 | 10篇 |
2022年 | 42篇 |
2021年 | 48篇 |
2020年 | 24篇 |
2019年 | 40篇 |
2018年 | 28篇 |
2017年 | 24篇 |
2016年 | 29篇 |
2015年 | 31篇 |
2014年 | 30篇 |
2013年 | 56篇 |
2012年 | 33篇 |
2011年 | 52篇 |
2010年 | 27篇 |
2009年 | 28篇 |
2008年 | 15篇 |
2007年 | 19篇 |
2006年 | 13篇 |
2005年 | 13篇 |
2004年 | 4篇 |
2003年 | 8篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有627条查询结果,搜索用时 140 毫秒
31.
Luciane Madureira Almeida Juliana Ferreira Floriano Thuanne Pires Ribeiro Lais Nogueira Magno Lígia Souza Lima Silveira da Mota Nei Peixoto Fátima Mrué Paulo Melo-Reis Ruy de Souza Lino Junior Carlos Frederico de Oliveira Graeff Pablo José Gonçalves 《Journal of materials science. Materials in medicine》2014,25(9):2153-2162
The latex obtained from Hancornia speciosa is used in folk medicine for treatment of several diseases, such as acne, warts, diabetes, gastritis and inflammation. In this work, we describe the biocompatibility assessment and angiogenic properties of H. speciosa latex and its potential application in medicine. The physical–chemical characterization was carried out following different methodologies (CHN elemental analyses; thermogravimetric analyses and Fourier transform infrared spectroscopy). The biocompatibility was evaluated through cytotoxicity and genotoxicity tests in fibroblast mouse cells and the angiogenic properties were evaluated using the chick chorioallantoic membrane (CAM) assay model. The physical–chemical results showed that the structure of Hancornia speciosa latex biomembrane is very similar to that of Hevea brasiliensis (commercially available product). Moreover, the cytotoxicity and genotoxicity assays showed that H. speciosa latex is biocompatible with life systems and can be a good biomaterial for medical applications. The CAM test showed the efficient ability of H. speciosa latex in neovascularization of tissues. The histological analysis was in accordance with the results obtained in the CAM assay. Our data indicate that the latex obtained from H. speciosa and eluted in water showed significant angiogenic activity without any cytotoxic or genotoxic effects on life systems. The same did not occur with H. speciosa latex stabilized with ammonia. Addition of ammonia does not have significant effects on the structure of biomembranes, but showed a smaller cell survival and a significant genotoxicity effect. This study contributes to the understanding of the potentialities of H. speciosa latex as a source of new phytomedicines. 相似文献
32.
Suhaila Mohamed Tan Lee Ming Juliana Md Jaffri 《Journal of the science of food and agriculture》2013,93(4):819-827
BACKGROUND: Catechin‐rich oil palm (Elaeis guineensis) leaf extract (OPLE) has good cardiovascular and phytoestrogenic properties. The OPLE (0.5 g day?1) was supplemented to young, healthy, adult human volunteers, and their cognitive learning abilities were compared to placebo‐controlled groups (N = 15). Their short‐term memories, spatial visualisations, processing speeds, and language skills, were assessed over 2 months by cognitive tests computer programs. RESULTS: Relative to the controls, volunteers taking OPLE had improved (P < 0.05) short‐term memory, after 1 month of intervention which became highly significant (P < 0.005) after 2 months. The spatial visualisation ability and processing speed improved (P < 0.05) after 2 months consumption. The dietary OPLE showed neuroprotection in nitric oxide‐deficient rats. The mechanisms involved systemic and cellular modulations that eventually enhance neuron survival. The longer the duration of OPLE consumption, the more significant was the enhancement, as shown for short‐term memory. CONCLUSION: This is the first report on the cognitive‐enhancing effects of dietary OPLE in humans. The computer‐assisted cognitive tests were simple, low in cost, errors and man hours, and hence are better than conventional cognitive test methods. In rats, the equivalent OPLE dose showed brain antioxidant enzymes modulating properties and neuroprotection under nitric oxide deficiency, with possibly neurogenesis in normal rats. This supported the effects in humans. © 2012 Society of Chemical Industry 相似文献
33.
Scientometrics - At the Leibniz Institute for Baltic Sea Research Warnemünde (the home institute of this paper), scientists have been exploring the common denominator between microplastics and... 相似文献
34.
Sustainability metrics for eco-technologies assessment, Part II. Life cycle analysis 总被引:1,自引:1,他引:0
Juliana Garcia Moretz-Sohn Monteiro Ofélia de Queiroz Fernandes Araújo José Luiz de Medeiros 《Clean Technologies and Environmental Policy》2009,11(4):459-472
This work presents a sustainability analysis of CO2 reuse to produce dimethyl carbonate (DMC) via ethylene oxide (ROUTE A) and via urea methanolysis (ROUTE B). Two different
technologies are considered in ROUTE A: reaction followed by separation and reactive distillation. Life cycle analyses of
the ROUTES are presented employing sustainability analysis performed in HYSYS process simulator, along with WAR Algorithm.
Process economical optimization is performed to maximize the processes profitability. A sustainability function, defined as
a 2D indicator involving both economical and environmental aspects, is calculated for the optimized processes. Additional
sustainability indexes are evaluated: material index, energy index, and ecoefficiency. The results, under both economical
and environmental aspects, show that ROUTE A is the most sustainable. The study also points to the relevance of the frontier
set between the domains cradle-to-gate and gate-to-gate in assessing process sustainability during LCA. 相似文献
35.
Visual flight rules (VFR) flight into instrument meteorological conditions (IMC) is a major safety hazard in general aviation. In this study we examined pilots' decisions to continue or divert from a VFR flight into IMC during a dynamic simulation of a cross-country flight. Pilots encountered IMC either early or later into the flight, and the amount of time and distance pilots flew into the adverse weather prior to diverting was recorded. Results revealed that pilots who encountered the deteriorating weather earlier in the flight flew longer into the weather prior to diverting and had more optimistic estimates of weather conditions than did pilots who encountered the deteriorating weather later in the flight. Both the time and distance traveled into the weather prior to diverting were negatively correlated with pilots' previous flight experience. These findings suggest that VFR flight into IMC may be attributable, at least in part, to poor situation assessment and experience rather than to motivational judgment that induces risk-taking behavior as more time and effort are invested in a flight. Actual or potential applications of this research include the design of interventions that focus on improving weather evaluation skills in addition to addressing risk-taking attitudes. 相似文献
36.
Verbal working memory involves two major components: a phonological store that holds auditory-verbal information very briefly and an articulatory rehearsal process that allows that information to be refreshed and thus held longer in short-term memory (A. Baddeley, 1996, 2000; A. Baddeley & G. Hitch, 1974). In the current study, the authors tested two groups of patients who were chosen on the basis of their relatively focal lesions in the inferior parietal (IP) cortex or inferior frontal (IF) cortex. Patients were tested on a series of tasks that have been previously shown to tap phonological storage (span, auditory rhyming, and repetition) and articulatory rehearsal (visual rhyming and a 2-back task). As predicted, IP patients were disproportionately impaired on the span, rhyming, and repetition tasks and thus demonstrated a phonological storage deficit. IF patients, however, did not show impairment on these storage tasks but did exhibit impairment on the visual rhyming task, which requires articulatory rehearsal. These findings lend further support to the working memory model and provide evidence of the roles of IP and IF cortex in separable working memory processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
37.
Juliana Vinholes Clara Grosso Paula B. Andrade Angel Gil-Izquierdo Patrícia Valentão Paula Guedes de Pinho Federico Ferreres 《Food chemistry》2011
Spergularia rubra is distributed all over the world, being its infusion used as diuretic. In spite of its large use, the antidiabetic, anti-cholinesterase and antioxidant activities of this species have not been assessed and its chemical composition is scarcely known. In the work herein a hydromethanolic extract was studied. 相似文献
38.
The present work investigated the photodegradation of real textile effluents by advanced oxidative process (AOP) using TiO2/H2O2/sunlight system. The procedures were carried out at ambient conditions in March 2005. The results were evaluated by COD reduction concomitant to the increase in inorganic ion concentration (mineralization) and the analysis of the effluent characteristic spectral wavelengths: 228, 254, and 284 nm (simple aromatic compounds), 310 nm (conjugated aromatic compounds), and 390, 450, and 530 (color). As this study is not restricted to the decolorization process, it allows a more reliable evaluation of effluent mineralization. The results indicate that solar radiation is as efficient as or even more efficient than artificial radiation was in previous studies and that it also allows a reduction in effluent treatment operational costs. 相似文献
39.
Juliana A. Calabria Wander L. Vasconcelos Aldo R. Boccaccini 《Ceramics International》2009,35(2):665-671
The environmental degradation of adobe and fired clay brick was studied. Leaching media based on Na2S2O5 solution and deionized water were used. The microstructure of the samples was evaluated by X-ray powder diffraction, nitrogen adsorption–desorption (BET method), Fourier transform infrared spectroscopy and scanning electron microscopy. The predominant phases detected were kaolinite and quartz for both the adobe and fired brick samples. The high surface reactivity, associated with a large amount of OH groups, contributes to the significant degradation of adobe. The fired clay brick showed a significant decrease in the average pore diameter after the first day of the leaching process; its specific surface area exhibited a reduction of about three orders of magnitude. The results of the present investigation contribute to a better understanding of the correlation between structure and leaching behaviour in adobe and clay brick, attending the renewed interest in these materials as environmentally attractive building blocks. 相似文献
40.