全文获取类型
收费全文 | 381篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
化学 | 243篇 |
晶体学 | 1篇 |
力学 | 5篇 |
数学 | 101篇 |
物理学 | 33篇 |
出版年
2019年 | 3篇 |
2016年 | 7篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 9篇 |
2012年 | 10篇 |
2011年 | 8篇 |
2010年 | 5篇 |
2009年 | 8篇 |
2008年 | 11篇 |
2007年 | 9篇 |
2006年 | 6篇 |
2005年 | 10篇 |
2004年 | 7篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2000年 | 3篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 14篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 11篇 |
1977年 | 9篇 |
1976年 | 9篇 |
1975年 | 12篇 |
1974年 | 11篇 |
1973年 | 9篇 |
1972年 | 14篇 |
1971年 | 5篇 |
1970年 | 9篇 |
1969年 | 5篇 |
1968年 | 10篇 |
1963年 | 3篇 |
1962年 | 7篇 |
1961年 | 3篇 |
1928年 | 4篇 |
排序方式: 共有383条查询结果,搜索用时 78 毫秒
21.
Cleoci Beninca Tiago André Denck Colman Luiz Gustavo Lacerda Marco Aurélio da Silva Carvalho Filho Ivo Mottin Demiate Gilbert Bannach Egon Schnitzler 《Journal of Thermal Analysis and Calorimetry》2013,111(3):2217-2222
The use of chemically modified starches is widely accepted in various industries, with several applications. In this research, natural cassava starch granules were treated with standard sodium hypochlorite solution at 0.8, 2.0, and 5.0 g Cl/100 g starch. The native and modified starch samples were investigated by means of the following techniques: simultaneous thermogravimetry–differential thermal analysis, which allowed us to verify the thermal decomposition associated with endothermic or exothermic phenomena; and differential scanning calorimetry that was used to determine gelatinization enthalpy as well as the rapid viscoamylographic analysis that provided the pasting temperature and viscosity. By means of non-contact-atomic force microscopy method and X-ray powder patterns diffractometry, it was possible to observe the surface morphology, topography of starch granules, and alterations in the granules’ crystallinity. 相似文献
22.
Lucas Stiegler Ribeiro Layse do Prado Cordoba Tiago André Denck Colman Cristina Soltovsti de Oliveira Marina Morena Pereira Andrade Egon Schnitzler 《Journal of Thermal Analysis and Calorimetry》2014,117(2):935-942
When starch is incorporated into puddings, desserts, and other foods containing sugar as the main ingredient, it will have an effect on the gelatinisation temperature and pasting properties. Many studies have been undertaken to investigate the effect of several sugars in foods and starches, as well as their physicochemical and functional properties. These studies have verified the significant influence on these properties, which are dependent on the nature of sugar and of starch. In this study, pinhão starch was extracted in the laboratory and was added, stirring for 60 min, to solutions at 1 % of each of the following sugars: fructose, glucose, sucrose, and 0.5 % fructose and 0.5 % glucose. After this time, the slurry was filtered, washed, dried at 40 °C and kept in a desiccator over anhydrous calcium chloride until constant mass. The effects of each sugar on the surface of the pinhão starch granules were observed using the non-contact method of atomic force microscopy, whereby it was possible to verify a decrease in the average diameter and an increase in the average roughness. X-ray diffractometry made it possible to evaluate the degree of relative crystallinity, which was proportional to the roughness and inversely proportional to the gelatinisation enthalpy (ΔH), which was studied by differential scanning calorimetry. 相似文献
23.
Enzymatic Conversion of Flavonoids using Bacterial Chalcone Isomerase and Enoate Reductase 下载免费PDF全文
Dipl.‐Biol. Mechthild Gall Dipl.‐Biochem. Maren Thomsen Dipl.‐Biochem. Christin Peters Dr. Ioannis V. Pavlidis M. Sc. Patrick Jonczyk M. Sc. Philipp P. Grünert Dr. Sascha Beutel Prof. Dr. Thomas Scheper Egon Gross Dr. Michael Backes Dr. Torsten Geißler Dr. Jakob P. Ley Dr. Jens‐Michael Hilmer Dr. Gerhard Krammer Dr. Gottfried J. Palm Prof. Dr. Winfried Hinrichs Prof. Dr. Uwe T. Bornscheuer 《Angewandte Chemie (International ed. in English)》2014,53(5):1439-1442
Flavonoids are a large group of plant secondary metabolites with a variety of biological properties and are therefore of interest to many scientists, as they can lead to industrially interesting intermediates. The anaerobic gut bacterium Eubacterium ramulus can catabolize flavonoids, but until now, the pathway has not been experimentally confirmed. In the present work, a chalcone isomerase (CHI) and an enoate reductase (ERED) could be identified through whole genome sequencing and gene motif search. These two enzymes were successfully cloned and expressed in Escherichia coli in their active form, even under aerobic conditions. The catabolic pathway of E. ramulus was confirmed by biotransformations of flavanones into dihydrochalcones. The engineered E. coli strain that expresses both enzymes was used for the conversion of several flavanones, underlining the applicability of this biocatalytic cascade reaction. 相似文献
24.
25.
Egon Fahr 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》1973,85(4):179-179
26.
Dr. Egon Joachim 《Mathematische Zeitschrift》1969,111(1):46-52
Ohne Zusammenfassung 相似文献
27.
Summary This work describes the dialysis, the determination of the total soap content in the latex system by conductometric titration, the effect of dilution on soap distribution between the aqueous and polymer phases, the confirmation of the average diameter of the latex particles, the electrophoretic behavior, and the establishment of the solids content below which the latex behaves according toBeer's law for the transmission of light. The colloidal system used in this study was a styrenebutadiene ( 11) latex (Naugatex 2740) with potassium salt of the disproportionated rosin (Dresinate 214) as emulsifier.
Supported by the U.S. Army Research Office (Durham), Grant No. DA-ARO(D)-31-124-G 656.
Part of a Ph. D. Thesis byC. G. Force. 相似文献
Zusammenfassung An einem Styrol-Butadien (11)-Latex (Naugatex 2740) mit dem Kaliumsalz von disproportioniertem Harz (Dresinate 214) als Emulgator wurden folgende Untersuchungen durchgeführt: Dialyse, konduktometrische Bestimmung der Gesamtkonzentration an Seife im Latex, Einfluß der Verdünnung auf die Verteilung der Seife zwischen wässeriger und polymerer Phase, Ermittlung des mittleren Durchmessers der Partikel und elektrophoretisches Verhalten. Weiterhin wurde noch festgestellt, bis zu welchem Feststoffgehalt dasBeersche Gesetz für die Latexssuspension gilt.
Supported by the U.S. Army Research Office (Durham), Grant No. DA-ARO(D)-31-124-G 656.
Part of a Ph. D. Thesis byC. G. Force. 相似文献
28.
29.
Ohne Zusammenfassung 相似文献
30.
The polyhedron defined by all the split cuts obtainable directly (i.e. without iterated cut generation) from the LP-relaxation
P of a mixed integer program (MIP) is termed the (elementary, or rank 1) split closure of P. This paper deals with the problem of optimizing over the elementary split closure. This is accomplished by repeatedly solving
the following separation problem: given a fractional point, say x, find a rank-1 split cut violated by x or show that none exists. Following Caprara and Letchford [17], we formulate this separation problem as a nonlinear mixed
integer program that can be treated as a parametric mixed integer linear program (PMILP) with a single parameter in the objective
function and the right hand side. We develop an algorithmic framework to deal with the resulting PMILP by creating and maintaining
a dynamically updated grid of parameter values, and use the corresponding mixed integer programs to generate rank 1 split
cuts. Our approach was implemented in the COIN-OR framework using CPLEX 9.0 as a general purpose MIP solver. We report our
computational results on well-known benchmark instances from MIPLIB 3.0 and several classes of structured integer and mixed
integer problems. Our computational results show that rank-1 split cuts close more than 98% of the duality gap on 15 out of
41 mixed integer instances from MIPLIB 3.0. More than 75% of the duality gap can be closed on an additional 10 instances.
The average gap closed over all 41 instances is 72.78%. In the pure integer case, rank-1 split cuts close more than 75% of
the duality gap on 13 out of 24 instances from MIPLIB 3.0. On average, rank 1 split cuts close about 72% of the duality gap
on these 24 instances. We also report results on several classes of structured problems: capacitated versions of warehouse
location, single-source facility location, p-median, fixed charge network flow, multi-commodity network design with splittable and unsplittable flows, and lot sizing.
The fraction of the integrality gap closed varies for these problem classes between 100 and 67%. We also gathered statistics
on the average coefficient size (absolute value) of the disjunctions generated. They turn out to be surprisingly small.
Research was supported by the National Science Foundation through grant #DMI-0352885 and by the Office of Naval Research through
contract N00014-03-1-0133. 相似文献