全文获取类型
收费全文 | 1712篇 |
免费 | 103篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 628篇 |
金属工艺 | 19篇 |
机械仪表 | 61篇 |
建筑科学 | 66篇 |
矿业工程 | 1篇 |
能源动力 | 47篇 |
轻工业 | 344篇 |
水利工程 | 8篇 |
石油天然气 | 7篇 |
无线电 | 84篇 |
一般工业技术 | 170篇 |
冶金工业 | 193篇 |
原子能技术 | 8篇 |
自动化技术 | 177篇 |
出版年
2024年 | 3篇 |
2023年 | 20篇 |
2022年 | 118篇 |
2021年 | 113篇 |
2020年 | 55篇 |
2019年 | 61篇 |
2018年 | 60篇 |
2017年 | 56篇 |
2016年 | 63篇 |
2015年 | 55篇 |
2014年 | 66篇 |
2013年 | 107篇 |
2012年 | 102篇 |
2011年 | 103篇 |
2010年 | 89篇 |
2009年 | 87篇 |
2008年 | 93篇 |
2007年 | 71篇 |
2006年 | 59篇 |
2005年 | 50篇 |
2004年 | 41篇 |
2003年 | 26篇 |
2002年 | 38篇 |
2001年 | 31篇 |
2000年 | 20篇 |
1999年 | 21篇 |
1998年 | 35篇 |
1997年 | 32篇 |
1996年 | 22篇 |
1995年 | 22篇 |
1994年 | 10篇 |
1993年 | 11篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 11篇 |
1989年 | 4篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1976年 | 12篇 |
1974年 | 2篇 |
1972年 | 3篇 |
1969年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有1815条查询结果,搜索用时 15 毫秒
51.
Piubelli GC Hoffmann-Campo CB Moscardi F Miyakubo SH de Oliveira MC 《Journal of chemical ecology》2005,31(7):1509-1525
The identification and quantification of flavonoids (rutin and genistin) present in extracts of soybean genotypes, and their effects on the biology and physiology of Anticarsia gemmatalis Hübner (Lep.: Noctuidae) were studied. Analysis of covariance and bicoordinate utilization plots were used to remove the effect of feeding time from pupal weight and consumption as well as to separate pre- and postingestive effects of treatment on A. gemmatalis growth. Genotypes PI 274454, PI 227687, and “IAC-100” extracts in general, caused higher mortality, negatively influenced initial larval and pupal weight, and elongated larval cycle. Larvae fed on the “IAC-100” extract diet ingested larger amounts of food per unit of time, but were less efficient in its conversion to biomass. Leaf extracts of PI 227687 had the largest concentration of rutin (quercitin 3-O-rhamnosylglucoside), followed by PI 274454, and “IAC-100”; PI 74454 also had the highest genistin (genistein 7-O-glucoside) content. The susceptible cultivar “BR-16” showed only a kaempferol-based flavonoid in its chemical profile, indicating that after successive crosses, secondary compounds responsible for plant defenses were eliminated. Genotypes PI 274454, PI 227687, and “IAC-100” showed accentuated resistance characteristics and were considered inadequate sources for the development of A. gemmatalis. Considering rutin and genistin concentration in these genotypes, it is suggested that flavonoids are important factors conferring resistance to A. gemmatalis. 相似文献
52.
Marina Cerdeira Valentina Pastore Liliana V. Vera Silvana Martini Roberto J. Candal María L. Herrera 《European Journal of Lipid Science and Technology》2005,107(12):877-885
The effect of highly hydrophobic emulsifiers, the palmitic sucrose ester P‐170 (hydrophilic/lipophilic balance (HLB) = 1.0), the stearic sucrose ester S‐170 (HLB = 1.0), the polyglycerol ester decaglycerol decastearate DAS 7S (HLB = 3.7) and the polyglycerol ester decaglycerol dodecabehenate DDB 750 (HLB = 2.6), on the nucleation of a high melting point milk fat fraction (HMF) and its blends with sunflower oil (SFO) was investigated by polarized laser light turbidimetry, X‐ray diffractometry and polarized light microscopy (PLM). Addition of polyglycerol esters accelerated nucleation, giving shorter induction times for the same supercooling. On the contrary, sucrose esters inhibited nucleation since induction times were elongated in all conditions selected. Addition of emulsifiers modified the polymorphic behavior in the blends with SFO. The β' form was promoted especially with the addition of S‐170. DAS 7S and DDB 750 promoted crystallization. PLM images showed many small crystals that did not appear in HMF images. Addition of P‐170 and S‐170 delayed nucleation and inhibited crystal growth. Crystals were notoriously smaller than the ones that appeared in HMF images. The Fisher–Turnbull model was used to calculate activation free energies of nucleation. In all cases, sucrose esters elevated the energy barrier for nucleation. Polyglycerol esters, however, if they had an effect on the energy barrier, lowered the values. 相似文献
53.
Silvana?Martini Constantin?Bertoli Maria?Lidia?Herrera Ian?Neeson Alejandro?MarangoniEmail author 《Journal of the American Oil Chemists' Society》2005,82(5):305-312
An ultrasonic technique was developed to study the crystallization process of edible fats on-line. A chirp wave was used instead
of the conventional pulser signal, thus achieving a higher signal-to-noise ratio. This enabled measurements to be made in
concentrated systems [≈20% solid fat content (SFC)] through a 8.11-cm thick sample without significant signal loss. Fat samples
were crystallized at 20, 25, and 30°C at a constant agitation rate of 400 rpm for 90 min. The crystallization process was
followed by ultrasonic spectroscopy and a low-resolution pulsed nuclear magnetic resonance spectrometer. Specific relationships
were found between ultrasonic parameters [integrated response, time of flight (TF), and full width half maximum] and SFC.
TF, which is an indirect measurement of the ultrasonic velocity (v), was highly correlated to SFC (r
2>0.9) in a linear fashion (v=2.601 SFC+1433.0). 相似文献
54.
Ebenezer A. Ifeduba Silvana Martini Casimir C. Akoh 《Journal of the American Oil Chemists' Society》2016,93(1):61-67
The objective of this study was to produce low saturated, zero‐trans, interesterified fats with 20 or 30 % saturated fatty acids (SFA) such as C16:0 or C18:0. Tripalmitin (TP) or tristearin (TS) was blended with high oleic sunflower oil (HOSO) at different ratios (0.1:1, 0.3:1, and 0.5:1 [w/w]). Total C16:0 and C18:0 compositions of the resulting TP/HOSO and TS/HOSO blends, respectively, were plotted against blending ratios. Linear interpolation was used to estimate blending ratios that would yield physical blends (PB) with 20 or 30 % SFA. Interesterified blends (IB) were then synthesized from the customized PB using Lipozyme TL IM as the biocatalyst. Total and sn‐2 fatty acid compositions, triacylglycerol (TAG) molecular species, thermal behavior, and oxidative stability of PB and IB were compared. The total fatty acid compositions of PB and IB were similar but fatty acid positional distributions and TAG molecular species composition differed. IB contained 5–10 % more SFA at the sn‐2 position than corresponding PB. Furthermore, interesterification generated mono‐ and disaturated TAG species which resulted in broader melting profiles for IB. However, IB had lower oxidative stability than PB. The reformulation of food products with zero‐trans interesterified fats may be advantageous to the reduction of cardiovascular disease burden in the population. 相似文献
55.
Carla M. Felcher Emilia S. Bogni Edith C. Kordon 《International journal of molecular sciences》2022,23(3)
The IL-6 cytokine family is a group of signaling molecules with wide expression and function across vertebrates. Each member of the family signals by binding to its specific receptor and at least one molecule of gp130, which is the common transmembrane receptor subunit for the whole group. Signal transduction upon stimulation of the receptor complex results in the activation of multiple downstream cascades, among which, in mammary cells, the JAK-STAT3 pathway plays a central role. In this review, we summarize the role of the IL-6 cytokine family—specifically IL-6 itself, LIF, OSM, and IL-11—as relevant players during breast cancer progression. We have compiled evidence indicating that this group of soluble factors may be used for early and more precise breast cancer diagnosis and to design targeted therapy to treat or even prevent metastasis development, particularly to the bone. Expression profiles and possible therapeutic use of their specific receptors in the different breast cancer subtypes are also described. In addition, participation of these cytokines in pathologies of the breast linked to lactation and involution of the gland, as post-partum breast cancer and mastitis, is discussed. 相似文献
56.
Juhee Lee Sarah A. Willett Casimir C. Akoh Silvana Martini 《Journal of the American Oil Chemists' Society》2022,99(2):141-151
The purpose of this research was to determine the effect of high-intensity ultrasound (HIU) on physical properties, degree of oxidation, and oxidative stability of structured lipids (SLs). Caprylic acid (C) and stearic acid (S) were incorporated into menhaden oil using Lipozyme® 435 lipase to obtain five samples: (1) LC 20 (menhaden oil with 20% of C), (2) LC 30 (menhaden oil with 30% C), (3) LS 20 (menhaden oil with 20% S), (4) LS 30 (menhaden oil with 30% S), and (5) Blend C (menhaden oil with 16.24% C and 13.04% S). Samples were crystallized for 90 min at the following temperatures: (1) LC 20 at 15.5°C, (2) LC 30 at 17.5°C, (3) LS 20 at 24°C, (4) LS 30 at 30°C, and (5) Blend C at 18.0°C, and HIU was applied at the onset of crystallization. Physical properties, degree of oxidation, and oxidative stability were evaluated in sonicated and nonsonicated samples. All SLs had statistically higher G′ after sonication. Sonicated LS 30, LC 30, and Blend C had a higher melting enthalpy than the nonsonicated ones, while enthalpy values in sonicated LS 20 and LC 20 samples were not statistically different than the nonsonicated ones. No significant difference between sonicated and nonsonicated samples was observed in peroxide values (1.2 ± 0.1 meq/kg, p > 0.05) and in the oxidative stability index (6.3 ± 0.2 h, p > 0.05). These results showed that HIU was effective at changing physical properties without affecting the oxidation of the samples. 相似文献
57.
Laura Marise de Freitas Giovana Maria Fioramonti Calixto Marlus Chorilli Ju?aíra Stella M. Giusti Vanderlei Salvador Bagnato Nikolaos S. Soukos Mansoor M. Amiji Carla Raquel Fontana 《International journal of molecular sciences》2016,17(5)
Antimicrobial photodynamic therapy (aPDT) is increasingly being explored for treatment of periodontitis. Here, we investigated the effect of aPDT on human dental plaque bacteria in suspensions and biofilms in vitro using methylene blue (MB)-loaded poly(lactic-co-glycolic) (PLGA) nanoparticles (MB-NP) and red light at 660 nm. The effect of MB-NP-based aPDT was also evaluated in a clinical pilot study with 10 adult human subjects with chronic periodontitis. Dental plaque samples from human subjects were exposed to aPDT—in planktonic and biofilm phases—with MB or MB-NP (25 µg/mL) at 20 J/cm2
in vitro. Patients were treated either with ultrasonic scaling and scaling and root planing (US + SRP) or ultrasonic scaling + SRP + aPDT with MB-NP (25 µg/mL and 20 J/cm2) in a split-mouth design. In biofilms, MB-NP eliminated approximately 25% more bacteria than free MB. The clinical study demonstrated the safety of aPDT. Both groups showed similar improvements of clinical parameters one month following treatments. However, at three months ultrasonic SRP + aPDT showed a greater effect (28.82%) on gingival bleeding index (GBI) compared to ultrasonic SRP. The utilization of PLGA nanoparticles encapsulated with MB may be a promising adjunct in antimicrobial periodontal treatment. 相似文献
58.
Viviane Muniz da Silva Fragoso Carla Patrícia de Morais Coura Luanda Yanaan Hoppe Marília Amável Gomes Soares Dilson Silva Celia Martins Cortez 《International journal of molecular sciences》2016,17(1)
The aim of this work was to study the interaction of sulpiride with human serum albumin (HSA) and bovine serum albumin (BSA) through the fluorescence quenching technique. As sulpiride molecules emit fluorescence, we have developed a simple mathematical model to discriminate the quencher fluorescence from the albumin fluorescence in the solution where they interact. Sulpiride is an antipsychotic used in the treatment of several psychiatric disorders. We selectively excited the fluorescence of tryptophan residues with 290 nm wavelength and observed the quenching by titrating HSA and BSA solutions with sulpiride. Stern-Volmer graphs were plotted and quenching constants were estimated. Results showed that sulpiride form complexes with both albumins. Estimated association constants for the interaction sulpiride–HSA were 2.20 (±0.08) × 104 M−1, at 37 °C, and 5.46 (±0.20) × 104 M−1, at 25 °C. Those for the interaction sulpiride-BSA are 0.44 (±0.01) × 104 M−1, at 37 °C and 2.17 (±0.04) × 104 M−1, at 25 °C. The quenching intensity of BSA, which contains two tryptophan residues in the peptide chain, was found to be higher than that of HSA, what suggests that the primary binding site for sulpiride in albumin should be located next to the sub domain IB of the protein structure. 相似文献
59.
Danielle G. Queiroz Carla M. F. da Silva Mario Minale Daniel Merino Elizabete F. Lucas 《加拿大化工杂志》2022,100(1):44-53
It is important from both a strategic and economic standpoint to study the mechanism of formation of water/oil emulsions, to predict their increase of viscosity with respect to that of the crude oil, and to obtain information about the stability vs separation of these substances (since their presence can impair oil processing and distribution). The objective of this work was to ascertain the influence of monoethylene glycol (MEG) on these parameters and its action mechanism. The addition of MEG in different proportions in the oil emulsions significantly changed the flow curve of the emulsion, passing from a quasi-Newtonian one to a shear thinning behaviour. Besides this, when MEG was present at low concentrations, the demulsification process was slow and an increase in concentration made the emulsions more stable than samples containing the same aqueous phase proportion. Under the conditions studied, the addition of MEG did not reduce the quantity of the aqueous phase separated compared to the emulsions free of MEG, but significantly delayed the demulsification process. Rheology provided important information regarding the phase separation process of the aqueous phase in oil phase emulsions, and dynamic testing suggested that the most relevant effect of the addition of MEG is an increase of the emulsion elasticity that can be correlated with the increase in the emulsion stability observed by bottle test and Turbiscan. 相似文献
60.
Moacir Fernandes Ferreira Júnior Elaine Angélica Ribeiro Mundim Guimes Rodrigues Filho Carla da Silva Meireles Daniel Alves Cerqueira Rosana Maria Nascimento de Assunção Marcos Marcolin Mara Zeni 《Polymer Bulletin》2011,66(3):377-389
Cellulose, obtained both from sugarcane bagasse and mango seeds, was used for synthesizing cellulose acetate in order to produce asymmetric membranes. These were compared to membranes of commercial cellulose acetate (Rhodia). All produced membranes were asymmetric, characterized by the presence of a dense skin and a porous support. Differences regarding the morphology of the surfaces as well as of the porous support can be noticed. Scanning Electron Microscopy (SEM) showed that the morphology of the superficial layer, responsible for transport, depends on the different lignin content of the starting material and also on the viscosity average molecular weight of the cellulose acetates produced from sugarcane bagasse, mango seed, and Rhodia’s commercial cellulose acetate. 相似文献