全文获取类型
收费全文 | 167篇 |
免费 | 9篇 |
专业分类
化学工业 | 67篇 |
金属工艺 | 3篇 |
机械仪表 | 5篇 |
建筑科学 | 1篇 |
能源动力 | 4篇 |
轻工业 | 29篇 |
无线电 | 5篇 |
一般工业技术 | 28篇 |
冶金工业 | 22篇 |
原子能技术 | 3篇 |
自动化技术 | 9篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 2篇 |
2019年 | 6篇 |
2018年 | 8篇 |
2017年 | 7篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 5篇 |
2013年 | 8篇 |
2012年 | 7篇 |
2011年 | 10篇 |
2010年 | 6篇 |
2009年 | 9篇 |
2008年 | 13篇 |
2007年 | 10篇 |
2006年 | 3篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 8篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1993年 | 3篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 1篇 |
排序方式: 共有176条查询结果,搜索用时 15 毫秒
31.
The lipid concentration and fatty acid composition of the whole liver and of cultured hepatocytes isolated from the livers
of rats fed ad libitum (fed), fasted for 24 hr (fasted), or fasted for 48 hr and then refed a fat-free, high carbohydrate
diet for 48 hr (refed) was studied. Hepatocytes were maintained as monolayer cultures in serum-free, lipid-free media and
their fatty acid composition was analyzed at 3, 24, 48, 72 and 96 hr. The livers of fed animals, as well as their hepatocytes,
contained less total lipid than those from animals on either of the other dietary regimes. Livers of fasted animals had three
times the amount of lipid found in the livers of fed animals, and the livers of refed animals contained five times the amount
of lipid as the livers of fed animals (all based on mg lipid/g wet weight of liver). The fatty acid composition of hepatocytes
after 3 hr of culturing was very similar to that of fresh liver when compared in each of the dietary regimes. However, while
the fatty acid compositions of livers and hepatocytes from fed and fasted animals were similar, the pattern in liver of refed
animals was quite distinct from that of the fed animals. In the fed and fasted animals palmitic acid (16∶0), stearic acid
(18∶0), oleic acid (18∶1[n-9]), linoleic acid (18∶2[n-6]) and arachidonic acid (20∶4[n-6]) were the major fatty acids of the
liver; in refed animals 16∶0, palmitoleic acid (16∶1[n-7]), 18∶0, 18∶1(n-9) andcis-vaccenic acid (the n-7 isomer of oleic acid) were the major fatty acids. During maintenance in culture the 18∶1(n-9) content
of the hepatocytes increased in cells from livers of animals on all three dietary regimes. The polyunsaturated fatty acid
content was similar in fresh livers and isolated hepatocytes in all samples when compared on the basis of μg fatty acid/mg
of hepatocyte or liver protein. It was also found that the polyunsaturated fatty acid content of hepatocytes was remarkedly
stable with time of culture when the cells were incubated in serum-free, lipid-free medium. Thus, isolated hepatocytes maintained
in serum-free medium appear to be a possible system for the evaluation of the effects of prior nutritional status on fatty
acid metabolism in the whole animal, not subject to hormonal and other somatic influences which often complicate the interpretation
of such nutritional studies. 相似文献
32.
Docosahexaenoic Acid and Eicosapentaenoic Acid Did not Alter <Emphasis Type="Italic">trans</Emphasis>-10,<Emphasis Type="Italic">cis</Emphasis>-12 Conjugated Linoleic Acid Incorporation into Mice Brain and Eye Lipids 下载免费PDF全文
Madhuri?Vemuri Yuriko?Adkins Bruce?E.?Mackey Darshan?S.?KelleyEmail author 《Lipids》2017,52(9):763-769
trans 10,cis 12‐CLA has been reported to alter fatty acid composition in several non‐neurological tissues, but its effects are less known in neurological tissues. Therefore, the purpose of this study was to determine if CLA supplementation would alter brain and eye fatty acid composition and if those changes could be prevented by concomitant supplementation with docosahexaenoic acid (DHA; 22:6n3) or eicosapentaenoic acid (EPA; 20:5n3). Eight‐week‐old, pathogen‐free C57BL/6N female mice (n = 6/group) were fed either the control diet or diets containing 0.5% (w/w) t10,c12‐CLA in the presence or absence of either 1.5% DHA or 1.5% EPA for 8 weeks. CLA concentration was significantly (P < 0.05) greater in the eye but not in the brain lipids of the CLA group when compared with the control group. The sums of saturated, monounsaturated, polyunsaturated fatty acids, and n3:n6 ratio did not differ between these two groups for both tissues. The n3:n6 ratio and concentrations of 20:5n3 and 22:5n3 were significantly greater, and those of 20:4n6, 22:4n6, and 22:5n6 were lesser in the CLA + DHA and CLA + EPA groups than in the control and CLA groups for either tissue. DHA concentration was higher in the CLA + DHA group only but not in the CLA + EPA group when compared with the CLA group for both tissues. The dietary fatty acids generally induced similar changes in brain and eye fatty acid concentration and at the concentrations used both DHA and EPA fed individually with CLA were more potent than CLA alone in altering the tissue fatty acid concentration. 相似文献
33.
Lingappa Rangaraj Siriyara J. Suresha Canchi Divakar Vikram Jayaram 《Metallurgical and Materials Transactions A》2008,39(7):1496-1505
Dense ZrB2-ZrC and ZrB2-ZrC
x∼0.67 composites have been produced by reactive hot pressing (RHP) of stoichiometric and nonstoichiometric mixtures of Zr and B4C powders at 40 MPa and temperatures up to 1600 °C for 30 minutes. The role of Ni addition on reaction kinetics and densification
of the composites has been studied. Composites of ∼97 pct relative density (RD) have been produced with the stoichiometric
mixture at 1600 °C, while the composite with ∼99 pct RD has been obtained with excess Zr at 1200 °C, suggesting the formation
of carbon deficient ZrC
x
that significantly aids densification by plastic flow and vacancy diffusion mechanism. Stoichiometric and nonstoichiometric
composites have a hardness of ∼20 GPa. The grain sizes of ZrB2 and ZrC
x∼0.67 are ∼0.6 and 0.4 μm, respectively, which are finer than those reported in the literature.
This article is based on a presentation given in the symposium entitled “Materials Behavior: Far from Equilibrium” as part
of the Golden Jubilee Celebration of Bhabha Atomic Research Centre, which occurred during December 15–16, 2006 in Mumbai,
India. 相似文献
34.
Leschkies KS Divakar R Basu J Enache-Pommer E Boercker JE Carter CB Kortshagen UR Norris DJ Aydil ES 《Nano letters》2007,7(6):1793-1798
We combine CdSe semiconductor nanocrystals (or quantum dots) and single-crystal ZnO nanowires to demonstrate a new type of quantum-dot-sensitized solar cell. An array of ZnO nanowires was grown vertically from a fluorine-doped tin oxide conducting substrate. CdSe quantum dots, capped with mercaptopropionic acid, were attached to the surface of the nanowires. When illuminated with visible light, the excited CdSe quantum dots injected electrons across the quantum dot-nanowire interface. The morphology of the nanowires then provided the photoinjected electrons with a direct electrical pathway to the photoanode. With a liquid electrolyte as the hole transport medium, quantum-dot-sensitized nanowire solar cells exhibited short-circuit currents ranging from 1 to 2 mA/cm2 and open-circuit voltages of 0.5-0.6 V when illuminated with 100 mW/cm2 simulated AM1.5 spectrum. Internal quantum efficiencies as high as 50-60% were also obtained. 相似文献
35.
M. Venkataravanappa R.B. Basavaraj G.P. Darshan B. Daruka Prasad S.C. Sharma P. Hema Prabha S. Ramani H. Nagabhushana 《中国稀土学报(英文版)》2018,36(7):690-702
Latent fingerprints (LFPs) are the major physical evidences for the identification of individuals during crime spot investigation. Till date, numerous methods were followed to visualize LFPs. However, simple, accurate, and cost-effective method has wide scope in advanced forensic field. In our work, Ca2SiO4:Dy3+ nanopowders (NPs) were fabricated via solution combustion route. The optimized sample was employed for the visualization of overlapped LFPs by the cost effective powder dusting method. The obtained results reveals the complete three levels of ridge characteristics with high sensitivity, reproducibility, selectivity, and reliability on various complex surfaces. The photoluminescence (PL) spectra consist of intense peaks at ~ 480 and 574 nm owing to 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 4f transitions of Dy3+ ions, respectively. The photometric properties confirm that the samples exhibit intense white emission with high color purity. Therefore, the prepared NPs could be a definitive choice as an advanced luminescent NPs for forensic, solid state lighting and portable FED devices. 相似文献
36.
Complete liquification time test coupled with solvent fractionation technique to detect adulteration of foreign fats in ghee 下载免费PDF全文
Neelam Upadhyay Anil Kumar Ankit Goyal Darshan Lal 《International Journal of Dairy Technology》2017,70(1):110-118
Complete liquification time (CLT) test (min:s) exploits the physical property of milk fat as the time required by solid fat to melt completely at a defined temperature. It has been used to detect adulteration of groundnut oil and goat body fat when added singly and in combination with ghee. The Complete liquification time test for samples containing a combination of adulterants was carried out before and after solvent fractionation. The results revealed that adulterants added individually could be detected at higher levels (15%, w/w, groundnut oil in cow ghee; and 10%, w/w, goat body fat in buffalo ghee), while fractionation reduced the detection limit to lowest level (10%, w/w) used in this study. 相似文献
37.
Narendra Bandaru Darshan Ajmera Krishna Manwani Sasmita Majhi Emila Panda 《Transactions of the Indian Institute of Metals》2017,70(5):1269-1275
High-resolution transmission electron microscopy analyses are carried out to understand the microstructure of the ultra-thin oxide-film grown on a (native) amorphous Al2O3-coated Al-0.8 at.% Mg alloy substrate at T = 600 K for t = 2 h and at pO2 of 1 × 10?2 Pa. This oxide-film is found to be non-uniformly thick with thicknesses varying from 1.50 to 4.60 nm. Occasionally, this oxide is found to diffuse into the Al–Mg alloy substrate, forming oxide thicknesses up to 10.5 nm. Overall, this oxide-film is found to consist of a mixed amorphous, (poly) crystalline and an intermediate amorphous-to-crystalline transition regions, with crystalline regions consisting mostly of MgO and the diffused oxide regions into the Al–Mg alloy substrate coated with γ-Al2O3. These observations are then compared with the experimental results obtained using angle-resolved X-ray Photoelectron Spectroscopy analysis and thermodynamic predictions for the growth of an ultra-thin oxide-film due to dry, thermal oxidation of Al–Mg alloy substrates. 相似文献
38.
T. Umasankar Patro G. Harikrishnan Ashok Misra Devang V. Khakhar 《Polymer Engineering and Science》2008,48(9):1778-1784
Nanocomposites of rigid polyurethane foam with unmodified vermiculite clay are synthesized. The clay is dispersed either in polyol or isocyanate before blending. The viscosity of the polyol is found to increase slightly on the addition of clay up to 5 pphp (parts per hundred parts of polyol by weight). The gel time and rise time are significantly reduced by the addition of clay, indicating that the clay acts as a heterogeneous catalyst for the foaming and polymerization reactions. X‐ray diffraction and transmission electron microscopy of the polyurethane composite foams indicate that the clay is partially exfoliated in the polymer matrix. The clay is found to induce gas bubble nucleation resulting in smaller cells with a narrower size distribution in the cured foam. The closed cell content of the clay nanocomposite foams increases slightly with clay concentration. The mechanical properties are found to be the best at 2.3 wt% of clay when the clay is dispersed in the isocyanate; the compressive strength and modulus normalized to a density of 40 kg/m3 are 40% and 34% higher than the foam without clay, respectively. The thermal conductivity is found to be 10% lower than the foam without clay. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers 相似文献
39.
Microporous activated carbon spheres (ACSs) with a high specific Brunauer–Emmet–Teller (BET) surface area were prepared from resole‐type spherical crosslinked phenolic beads (PBs) by physical activation. The PBs used as precursors were synthesized in our laboratory through the mixing of phenol and formaldehyde in the presence of an alkaline medium by suspension polymerization. The effects of the gasification time, temperature, and flow rate of the gasifying agent on the surface properties of ACSs were investigated. ACSs with a controllable pore structure derived from carbonized PBs were prepared by CO2 gasification. Surface properties of ACSs, such as the BET surface area, pore volume, pore size distribution, and pore diameters, were characterized with BET and Dubinin–Reduchkevich equations based on N2 adsorption isotherms at 77 K. The results showed that ACSs with a 32–88% extent of burn‐off with CO2 gasification exhibited a BET surface area ranging from 574 to 3101 m2/g, with the pore volume significantly increased from 0.29 to 2.08 cm3/g. The pore size and its distribution could be tailored by the selection of suitable conditions, including the gasification time, temperature, and flow rate of the gasifying agents. The experimental results of this analysis revealed that ACSs obtained under different conditions were mainly microporous. The development of the surface morphology of ACSs was also studied with scanning electron microscopy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
40.
Karuna Meghwal Vivek Sharma Darshan Lal Sumit Arora 《International Journal of Dairy Technology》2013,66(1):98-102
Grain formation is one of the critical attributes affecting consumer acceptability of ghee. It was observed that both control ghee and low‐cholesterol ghee had grains of 0.236 ± 0.006 and 0.250 ± 0.002 mm size after incubation at 29 °C for 24 h, respectively. The maximum grain yield was 63 ± 2.60% and 68 ± 1.15% at 26 °C in control and low‐cholesterol ghee, respectively. Ghee grains in both the cases were stable over a temperature range of 25° to 36 °C. Time taken by both the samples for onset of nucleation was 50 min. The study revealed that cholesterol removal did not affect the crystallisation behaviour. 相似文献