全文获取类型
收费全文 | 431篇 |
免费 | 44篇 |
专业分类
电工技术 | 1篇 |
综合类 | 2篇 |
化学工业 | 134篇 |
金属工艺 | 2篇 |
机械仪表 | 13篇 |
建筑科学 | 29篇 |
矿业工程 | 1篇 |
能源动力 | 9篇 |
轻工业 | 93篇 |
水利工程 | 4篇 |
无线电 | 12篇 |
一般工业技术 | 64篇 |
冶金工业 | 66篇 |
原子能技术 | 2篇 |
自动化技术 | 43篇 |
出版年
2023年 | 8篇 |
2022年 | 17篇 |
2021年 | 28篇 |
2020年 | 16篇 |
2019年 | 11篇 |
2018年 | 11篇 |
2017年 | 20篇 |
2016年 | 24篇 |
2015年 | 17篇 |
2014年 | 23篇 |
2013年 | 35篇 |
2012年 | 27篇 |
2011年 | 37篇 |
2010年 | 25篇 |
2009年 | 20篇 |
2008年 | 19篇 |
2007年 | 13篇 |
2006年 | 11篇 |
2005年 | 12篇 |
2004年 | 6篇 |
2003年 | 2篇 |
2002年 | 9篇 |
2001年 | 6篇 |
2000年 | 9篇 |
1999年 | 6篇 |
1998年 | 15篇 |
1997年 | 6篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1966年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有475条查询结果,搜索用时 62 毫秒
71.
In the present paper we analyzed the effect caused by different recovery diets enriched with n-3 polyunsaturated fatty acids (PUFA n-3) on thymus and serum lipid pattern. Severe depleted weanling Wistar rats (D) were divided in three groups that received during 10 days a 20% casein diet supplemented with EPA+DHA (group Cas), a 20% protein milk diet prepared using a commercial reduced-fat product enriched with linolenic and linoleic acids (group L) and a 20% casein diet as control group C. Cas and L gave each other 24 mg/day of PUFA n-3 being the ratio n-6/n-3 8.1/1 and 7.6/1, respectively. Thymus was removed and weighted and cell number were determined; blood was recollected and Total cholesterol, triacylglycerol, HDL and LDL-cholesterol fractions and myristic, palmitic, stearic, oleic, linoleic, linolenic, araquidonic, EPA and DHA fatty acid concentrations were measured in serum. Statistical analysis was performed using Anova test. Cell number were higher (p<0.01) in Cas (44.48+/-8.20) and in L (56.45+/-14.72) when compared to group D (1.80+/-0.70) and group C (23.70+/-4.04). L presented lower values of cholesterol, HDL and LDL-cholesterol (p<0.01) and higher values of triacylglycerol (p<0.05) when compared to Cas, being EPA (p<0.05) and DHA (p<0.01) higher in Cas. Being PUFA n-3 contribution the same in Cas and L, both diets were able to reverse the thymic athropy presenting a different hipolipemic behavior due to the different sources of PUFA n-3 used in the diets. 相似文献
72.
Both potassium and ammonium ferrierite (FK and FA, respectively) were impregnated with tungsten species using either tungstic
acid or ammonium metatungstate as precursors. The skeletal isomerization of 1-butene at 200–400°C, atmospheric pressure and
0.15 atm 1-butene partial pressure, was studied on samples with and without tungsten. Tungsten species on FK promote the isobutene
formation while those species on FA generate a synergetic effect over the isobutene production. The presence of tungsten species
improves the material stability and mainly, the isobutene yield. Starting the 1-butene feed over the catalytic bed at 200°C
and then increasing the reaction temperature to 400°C, makes it possible to avoid the low isobutene selectivity at short times-on-stream.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
73.
J. Liu J. J. Duruz V. de Nora J. A. Sekhar 《Clean Technologies and Environmental Policy》1999,1(3):180-186
After nearly 100 years of aluminum production with the Hall-Héroult cell, major innovations are being considered, mainly
in the materials of construction and the electrodes. This article presents a brief review of some of the innovations made
in anode materials. Such improvements lead to better cell efficiencies and environmental benefits; and open the door for improved
cell designs hithertofore not possible with available cell materials.
Received: 17 November 1998 / Accepted: 19 March 1999 相似文献
74.
Flexible power generation scenarios for biogas plants operated in Germany: impacts on economic viability and GHG emissions 下载免费PDF全文
Markus Lauer Martin Dotzauer Christiane Hennig Monique Lehmann Eva Nebel Jan Postel Nora Szarka Daniela Thrän 《国际能源研究杂志》2017,41(1):63-80
Biogas plants enable power to be generated in a flexible way so that variable, renewable energy sources can be integrated into the energy system. In Germany, the Renewable Energy Sources Act promotes flexible power generation in biogas plants. Two existing biogas plants in flexible operation were analyzed with respect to economic viability and greenhouse gas (GHG) emissions to assess the feasibility of flexible operation. To do this, a biogas technology simulation model was developed to reproduce the technical design of both biogas plants and to link this design with twelve flexibilization scenarios. The evaluation of the economic viability is based on a discounting method of investment appraisal. For assessing the level of GHG emissions, the life cycle assessment method has been applied. The results show that the profitability of flexibilization is contingent upon premium payments promoting flexibility and direct sales resulting from a higher electrical efficiency of new or additionally installed combined heat and power units. Overall, with respect to profitability, the results of the flexible power generation scenarios are dependent upon the properties of the technical plant, such as its power generation and gas storage capacities. Relative GHG emissions from flexible biogas plants show significantly lower values than for referenced fossil gas–steam power stations. Among the various scenarios, the results reveal that the level of GHG emissions especially depends on the number of operating hours of the additional combined heat and power unit(s). The results of the analyzed biogas plants showed no direct correlation between GHG emissions and the economic benefits. Overall, a flexible power generation of biogas plants may improve the economic viability as well as result in lower GHG emissions in comparison with a conventional base load operation. © 2016 The Authors. International Journal of Energy Research published by John Wiley & Sons Ltd. 相似文献
75.
Somayeh S. Tarighat Fei Fei Eun Ji Joo Hisham Abdel-Azim Lu Yang Huimin Geng Khuchtumur Bum-Erdene I. Darren Grice Mark von Itzstein Helen Blanchard Nora Heisterkamp 《International journal of molecular sciences》2021,22(22)
Environmentally-mediated drug resistance in B-cell precursor acute lymphoblastic leukemia (BCP-ALL) significantly contributes to relapse. Stromal cells in the bone marrow environment protect leukemia cells by secretion of chemokines as cues for BCP-ALL migration towards, and adhesion to, stroma. Stromal cells and BCP-ALL cells communicate through stromal galectin-3. Here, we investigated the significance of stromal galectin-3 to BCP-ALL cells. We used CRISPR/Cas9 genome editing to ablate galectin-3 in stromal cells and found that galectin-3 is dispensable for steady-state BCP-ALL proliferation and viability. However, efficient leukemia migration and adhesion to stromal cells are significantly dependent on stromal galectin-3. Importantly, the loss of stromal galectin-3 production sensitized BCP-ALL cells to conventional chemotherapy. We therefore tested novel carbohydrate-based small molecule compounds (Cpd14 and Cpd17) with high specificity for galectin-3. Consistent with results obtained using galectin-3-knockout stromal cells, treatment of stromal-BCP-ALL co-cultures inhibited BCP-ALL migration and adhesion. Moreover, these compounds induced anti-leukemic responses in BCP-ALL cells, including a dose-dependent reduction of viability and proliferation, the induction of apoptosis and, importantly, the inhibition of drug resistance. Collectively, these findings indicate galectin-3 regulates BCP-ALL cell responses to chemotherapy through the interactions between leukemia cells and the stroma, and show that a combination of galectin-3 inhibition with conventional drugs can sensitize the leukemia cells to chemotherapy. 相似文献
76.
Agustín Rascón-Chu Ana Luisa Martínez-LópezElizabeth Carvajal-Millán Nora E. Ponce de León-RenovaJorge A. Márquez-Escalante Alejandro Romo-Chacón 《Food chemistry》2009
Pectin was acid-extracted from low quality ‘Golden Delicious’ apple fruit, yielding 16% (w pectin/w apple fruit). Composition and some of its physicochemical and functional properties were assessed. The pectin fraction presented a galacturonic acid content of 65% (w/w), an esterification degree of 57%, an intrinsic viscosity, [η], of 307 ml/g and a molecular weight (Mw) of 112 kDa. Pectin gels were obtained in 60% (w/v) fructose and pH 2.7. Pectin gels at 2.0% and 3.0% (w/v) presented hardness values of 10.2 and 20.4 g after 12 h at 4 °C. The gel hardness was greatly affected by aging (20% and 25% decrease in 48 h for gels at 2% and 3%, respectively). The results attained suggest the use of this gum as a potential texturing agent for the food industry. 相似文献
77.
Amoa-Awua WK Terlabie NN Sakyi-Dawson E 《International journal of food microbiology》2006,106(3):343-347
Forty-two cultures of Bacillus species isolated from soybean dawadawa were screened for their proteolytic activity on Skim Milk Agar, amylolytic activity on Starch Agar, and ability to grow on Soybean Agar. Distinct differences were observed between the cultures for all the criteria. Eleven isolates were selected for laboratory fermentation trials and each produced soybean dawadawa which was found acceptable by a taste panel. The pH of the samples, which increased from 6.37-6.58 to 8.22-8.85 during fermentation, were significantly different at P< or =0.05 for the different cultures. In the fermented samples, Bacillus counts exceeded 10(9) cfu/g, with the population of only one sample being significantly different at P< or =0.05. A market focus group familiar with soybean dawadawa selected Bacillus subtilis 24BP(2) and B. subtilis FpdP(2) as the best potential starter cultures. A taste panel found no significant differences in overall acceptance between soybean dawadawa either fermented spontaneously or with B. subtilis 24BP(2) and also between soybean dawadawa fermented with either B. subtilis 24BP(2) or B. subtilis FpdP(2). 相似文献
78.
Hocine N 《Radiation protection dosimetry》2012,151(2):374-378
The calculated dose equivalent response as a function of the angle has been examined for the radiophotoluminescent (RPL) glass dosemeter that was exposed to narrow series X-ray, N-60, N-80, N-100, N-150, N-200, N-250, N-300, photon sources ((60)Co and (137)Cs) and beta-ray emitter ((90)Sr/(90)Y) while mounted on an ISO water slab phantom. The angular dose equivalent responses H(p)(10) and H(p)(0.07) were calculated using the Monte Carlo MCNPX code. The RPL dosemeter and the phantom were rotated in the horizontal and vertical planes from a variety of angles of interest. The results were compared with the experimental data. Good agreement was found between the measured and calculated values of the relative dose equivalent angular responses of the RPL dosemeter. 相似文献
79.
There is a need to support collaborative coordinated construction through the integration of work processes across various stakeholders, disciplines, and projects. Due to the fast-growing complexities of domain-wide coordination and collaboration, coupled with the emerging opportunities of knowledge sharing, a knowledge-based approach is believed to be the way to go. Knowledge-based process integration takes into account explicit and formal semantics (meaning) of processes. It aims at supporting seamless integration of knowledge-carrying processes. This paper presents a prototype collaborative portal for domain-wide process integration. The portal is ontology-based: semantic process representation is enabled through ontologies, and knowledge-based process integration is facilitated through an ontology merger. The portal aims at offering an efficient value-adding collaboration platform through multidimensional process integration for producing a common workflow that goes beyond listing of processes to a knowledge-enabled view. The prototype was evaluated through a focus group. 相似文献
80.
Murphy Nora A.; Lehrfeld Jonathan M.; Isaacowitz Derek M. 《Canadian Metallurgical Quarterly》2010,25(4):811
In 2 studies, we investigated age effects in the ability to recognize dynamic posed and spontaneous smiles. Study 1 showed that both young and older adult participants were above chance in their ability to distinguish between posed and spontaneous smiles in young adults. In Study 2, we found that young adult participant performance declined when judging a combination of both young and older adult target smiles, while older adult participants outperformed young adult participants in distinguishing between posed and spontaneous smiles. A synthesis of results across the 2 studies showed a small-to-medium age effect (d = ?0.40), suggesting that older adults have an advantage in discriminating between smile types. Mixed stimuli (i.e., a mixture of young and older adult faces) may impact accurate smile discrimination. In future research, both the sources (cues) and behavioral effects of age-related differences in the discrimination of positive expressions should be investigated. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献