全文获取类型
收费全文 | 698篇 |
免费 | 45篇 |
国内免费 | 1篇 |
学科分类
工业技术 | 744篇 |
出版年
2023年 | 5篇 |
2022年 | 7篇 |
2021年 | 30篇 |
2020年 | 12篇 |
2019年 | 16篇 |
2018年 | 21篇 |
2017年 | 21篇 |
2016年 | 23篇 |
2015年 | 20篇 |
2014年 | 22篇 |
2013年 | 53篇 |
2012年 | 28篇 |
2011年 | 47篇 |
2010年 | 29篇 |
2009年 | 31篇 |
2008年 | 32篇 |
2007年 | 31篇 |
2006年 | 12篇 |
2005年 | 12篇 |
2004年 | 19篇 |
2003年 | 14篇 |
2002年 | 8篇 |
2001年 | 8篇 |
2000年 | 12篇 |
1999年 | 15篇 |
1998年 | 45篇 |
1997年 | 40篇 |
1996年 | 27篇 |
1995年 | 16篇 |
1994年 | 17篇 |
1993年 | 11篇 |
1991年 | 2篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 12篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1966年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有744条查询结果,搜索用时 963 毫秒
61.
Intratumoral Thermal Reading During Photo‐Thermal Therapy by Multifunctional Fluorescent Nanoparticles 下载免费PDF全文
Elisa Carrasco Blanca del Rosal Francisco Sanz‐Rodríguez Ángeles Juarranz de la Fuente Patricia Haro Gonzalez Ueslen Rocha Kagola Upendra Kumar Carlos Jacinto José García Solé Daniel Jaque 《Advanced functional materials》2015,25(4):615-626
The tremendous development of nanotechnology is bringing us closer to the dream of clinical application of nanoparticles in photothermal therapies of tumors. This requires the use of specific nanoparticles that must be highly biocompatible, efficient light‐to‐heat converters and fluorescent markers. Temperature reading by the heating nanoparticles during therapy appears of paramount importance to keep at a minimum the collateral damage that could arise from undesirable excessive heating. In this work, this thermally controlled therapy is possible by using Nd3+ ion‐doped LaF3 nanocrystals. Because of the particular optical features of Nd3+ ions at high doping concentrations, these nanoparticles are capable of in vivo photothermal heating, fluorescent tumor localization and intratumoral thermal sensing. The successful photothermal therapy experiments here presented highlight the importance of controlling therapy parameters based on intratumoral temperature measurements instead of on the traditionally used skin temperature measurements. In fact, significant differences between intratumoral and skin temperatures do exist and could lead to the appearance of excessive collateral damage. These results open a new avenue for the real application of nanoparticle‐based photothermal therapy at clinical level. 相似文献
62.
PbS/CdS/ZnS Quantum Dots: A Multifunctional Platform for In Vivo Near‐Infrared Low‐Dose Fluorescence Imaging 下载免费PDF全文
Antonio Benayas Fuqiang Ren Elisa Carrasco Vicente Marzal Blanca del Rosal Belete A. Gonfa Ángeles Juarranz Francisco Sanz‐Rodríguez Daniel Jaque José García‐Solé Dongling Ma Fiorenzo Vetrone 《Advanced functional materials》2015,25(42):6650-6659
Over the past decade, near‐infrared (NIR)‐emitting nanoparticles have increasingly been investigated in biomedical research for use as fluorescent imaging probes. Here, high‐quality water‐dispersible core/shell/shell PbS/CdS/ZnS quantum dots (hereafter QDs) as NIR imaging probes fabricated through a rapid, cost‐effective microwave‐assisted cation exchange procedure are reported. These QDs have proven to be water dispersible, stable, and are expected to be nontoxic, resulting from the growth of an outer ZnS shell and the simultaneous surface functionalization with mercaptopropionic acid ligands. Care is taken to design the emission wavelength of the QDs probe lying within the second biological window (1000–1350 nm), which leads to higher penetration depths because of the low extinction coefficient of biological tissues in this spectral range. Furthermore, their intense fluorescence emission enables to follow the real‐time evolution of QD biodistribution among different organs of living mice, after low‐dose intravenous administration. In this paper, QD platform has proven to be capable (ex vivo and in vitro) of high‐resolution thermal sensing in the physiological temperature range. The investigation, together with the lack of noticeable toxicity from these PbS/CdS/ZnS QDs after preliminary studies, paves the way for their use as outstanding multifunctional probes both for in vitro and in vivo applications in biomedicine. 相似文献
63.
Vargas-Murga L Garcia-Alvarez A Roman-Viñas B Ngo J Ribas-Barba L van den Berg SJ Williamson G Serra-Majem L 《Food & function》2011,2(12):731-739
The popularity of herbal products, especially plant food supplements (PFS) and herbal medicine is on the rise in Europe and other parts of the world, with increased use in the general population as well as among specific subgroups encompassing children, women or those suffering from diseases such as cancer. The aim of this paper is to examine the PFS market structures in European Community (EC) Member States as well as to examine issues addressing methodologies and consumption data relating to PFS use in Europe. A revision of recent reports on market data, trends and main distribution channels, in addition an example of the consumption of PFS in Spain, is presented. An overview of the methods and administration techniques used to assess individual food consumption as a starting point, including their uses and limitations, as well as some examples of studies that collect Food Supplement (FS) information, including herbal/botanical/plant-derived products are also discussed. Additionally, the intake estimation process of food nutrients is described and used to propose the PFS ingredients intake estimation process. Nationally representative PFS consumption data is scarce in Europe. The majority of studies have been conducted in Scandinavia and the UK. However the heterogeneity of definitions, study design and objectives make it difficult to compare results and extrapolate conclusions. 相似文献
64.
Cefquinome sulfate behavior after intramammary administration in healthy and infected cows 总被引:1,自引:0,他引:1
Zonca A Gallo M Locatelli C Carli S Moroni P Villa R Cagnardi P 《Journal of dairy science》2011,94(7):3455-3461
Maintenance of adequate drug concentration at the site of infection is an important problem in mastitis antibiotic therapy, and the efficacy of intramammary β-lactams can be optimized by maintaining the drug concentration at the site of infection above the minimum inhibitory concentration (MIC) as long as possible. The most important pharmacokinetic and pharmacodynamic parameter for efficacy evaluation is time during which drug concentrations exceed the MIC (t > MIC). In this study, we assessed the pharmacokinetic profile of cefquinome (CFQ) after repeated intramammary administration in healthy cows and cows subclinically infected with Staphylococcus aureus as well as the MIC of Staph. aureus field strains. In addition, the degree of drug passage was investigated from udder to bloodstream by measuring systemic drug absorption in healthy and infected animals. Cefquinome concentrations were quantified by HPLC (UV-visible detection) in milk samples collected from quarters and from blood serum samples. The systemic drug absorption was negligible in healthy and subclinically infected animals (maximum concentration 0.09 ± 0.02 and 0.1 ± 0.01 μg/mL in healthy and subclinically infected animals, respectively). The MIC90 value for CFQ in Staph. aureus field strains (n = 20) was 0.24 μg/mL. The pharmacokinetic and pharmacodynamic evaluation, determined by t > MIC, showed an equal persistence of CFQ in all quarters, indicating an equivalent activity of the drug regardless of the pathological status of the udder. Moreover, with literature data regarding CFQ MIC, the t > MIC has been calculated for other bacterial species. 相似文献
65.
66.
Cecchinato A Penasa M De Marchi M Gallo L Bittante G Carnier P 《Journal of dairy science》2011,94(8):4205-4213
The aim of this study was to estimate heritabilities of rennet coagulation time (RCT) and curd firmness (a30) and their genetic correlations with test-day milk yield, composition (fat, protein, and casein content), somatic cell score, and acidity (pH and titratable acidity) using coagulating and noncoagulating (NC) milk information. Data were from 1,025 Holstein-Friesian (HF) and 1,234 Brown Swiss (BS) cows, which were progeny of 54 HF and 58 BS artificial insemination sires, respectively. Milk coagulation properties (MCP) of each cow were measured once using a computerized renneting meter and samples not exhibiting coagulation within 31 min after rennet addition were classified as NC milk. For NC samples, RCT was unobserved. Multivariate analyses, using Bayesian methodology, were performed to estimate the genetic relationships of RCT or a30 with the other traits and statistical inference was based on the marginal posterior distributions of parameters of concern. For analyses involving RCT, a right-censored Gaussian linear model was used and records of NC milk samples, being censored records, were included as unknown parameters in the model implementing a data augmentation procedure. Rennet coagulation time was more heritable [heritability (h2) = 0.240 and h2 = 0.210 for HF and BS, respectively] than a30 (h2 = 0.148 and h2 = 0.168 for HF and BS, respectively). Milk coagulation properties were more heritable than a single test-day milk yield (h2 = 0.103 and h2 = 0.097 for HF and BS, respectively) and less heritable than milk composition traits whose heritability ranged from 0.275 to 0.275, with the only exception of fat content of BS milk (h2 = 0.108). A negative genetic correlation, lower than −0.85, was estimated between RCT and a30 for both breeds. Genetic relationships of MCP with yield and composition were low or moderate and favorable. The genetic correlation of somatic cell score with RCT in BS cows was large and positive and even more positive were those of RCT with pH and titratable acidity in both breeds, ranging from 0.80 to 0.94. Including NC milk information in the data affected the estimated correlations and decreased the uncertainty associated with the estimation process. On the basis of the estimated heritabilities and genetic correlations, enhancement of MCP through selective breeding with no detrimental effects on yield and composition seems feasible in both breeds. Milk acidity may play a role as an indicator trait for indirect enhancement of MCP. 相似文献
67.
Ulloa JA Rosas-Ulloa P Ulloa-Rangel BE 《Journal of the science of food and agriculture》2011,91(3):572-577
BACKGROUND: The protein isolate obtained from safflower meal by aqueous extraction and ultrafiltration was evaluated for its physicochemical and functional properties. RESULTS: Protein, ash and moisture contents of the safflower protein isolate were 901, 51 and 45 g kg?1 respectively. Its water and oil absorption capacities were 2.22 mL H2O g?1 protein and 2.77 mL oil g?1 protein respectively. Least gelation concentration was 20 g kg?1 at pH 2, 6, 8 and 10 but 100 g kg?1 at pH 4. Emulsifying properties were also affected by the pH: emulsifying activity and emulsion stability at pH 6 were 82.5 and 100% respectively. The highest foaming capacity (126%) occurred at pH 2; however, it increased by 104% with the addition of 0.25 g glucose g?1 protein to the foam system. CONCLUSION: In the light of its functional properties found in this study, safflower protein isolate produced by ultrafiltration is recommended for use as an ingredient in food products such as salad dressing, meat products, mayonnaise, cakes, ice cream and desserts. Copyright © 2010 Society of Chemical Industry 相似文献
68.
Popcorning is a failure mechanism in plastic-encapsulated microcircuits. It occurs when the inherently hygroscopic encapsulant is rapidly exposed to high temperatures during reflow solder assembly of the component to a printed circuit card. At these temperatures the moisture absorbed by the molding compound vaporizes and rapidly expands leading to the development of high stresses. When these stresses exceed both the interfacial adhesion strength and the fracture toughness of the molding compound, delamination and cracking result. Cracking is accompanied by a characteristic pop sound (and thus the name popcorning). Popcorning can: lead to a long-term reliability problem, since the cracks can be a path for ionic contaminants, causing corrosion-induced failures; and result in sheared or cratered ball bonds, causing electrical failures 相似文献
69.
SF Penc B Pomahac T Winkler RA Dorschner E Eriksson M Herndon RL Gallo 《Canadian Metallurgical Quarterly》1998,273(43):28116-28121
Proteoglycans have been shown in vitro to bind multiple components of the cellular microenvironment that function during wound healing. To study the composition and function of these molecules when derived from an in vivo source, soluble proteoglycans released into human wound fluid were characterized and evaluated for influence on fibroblast growth factor-2 activity. Immunoblot analysis of wound fluid revealed the presence of syndecan-1, syndecan-4, glypican, decorin, perlecan, and versican. Sulfated glycosaminoglycan concentrations ranged from 15 to 65 microgram/ml, and treatment with chondroitinase B showed that a large proportion of the glycosaminoglycan was dermatan sulfate. The total glycosaminoglycan mixture present in wound fluid supported the ability of fibroblast growth factor-2 to signal cell proliferation. Dermatan sulfate, and not heparan sulfate, was the major contributor to this activity, and dermatan sulfate bound FGF-2 with Kd = 2.48 microM. These data demonstrate that proteoglycans released during wound repair are functionally active and provide the first evidence that dermatan sulfate is a potent mediator of fibroblast growth factor-2 responsiveness. 相似文献
70.
JA Marin-Neto MV Sim?es EM Ayres-Neto JL Attab-Santos L Gallo DS Amorim BC Maciel 《Canadian Metallurgical Quarterly》1995,113(2):826-834
Pathogenesis of chronic Chagas' heart disease may include various disturbances in the coronary circulation, that could be responsible for the myocardial lesions seen in human hearts and in experimental models of the disease. In this paper we critically reviewed the anatomical and functional abnormalities described in chronic chagasic patients, pertaining to the so-called vascular pathogenetic theory of Chagas' disease. The epicardial coronary arteries are usually free of significant obstructive disease in nonselected groups of chagasic patients examined at autopsy or by coronary angiography. However, chagasic patients who were studied after an episode of acute myocardial infarction, show the same patterns of atherosclerotic coronary artery disease seen in the general nonchagasic population. Studies of chagasic patients with angiographically normal coronary arteries, by several scintigraphy methods, revealed myocardial perfusion abnormalities which may be caused by the microcirculatory derangements described in animals experimentally infected with the T. cruzi. Since hypoperfusion has been detected in regions with normal or mildly impaired wall motion, it is likely that the microvascular disturbances precede and may be causative mechanism for the subsequent myocardial damage. We speculate that hibernating ventricular areas may occur in chagasic patients, on the basis of the evidence gathered from these studies. Recent investigations of chronic patients with Chagas' disease and chest pain showed attenuation of the vasomotor responses to physiological and pharmacological stimuli, in the epicardial coronary arteries. 相似文献