全文获取类型
收费全文 | 273篇 |
免费 | 19篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 9篇 |
2014年 | 7篇 |
2013年 | 15篇 |
2012年 | 23篇 |
2011年 | 24篇 |
2010年 | 15篇 |
2009年 | 19篇 |
2008年 | 29篇 |
2007年 | 14篇 |
2006年 | 17篇 |
2005年 | 13篇 |
2004年 | 10篇 |
2003年 | 22篇 |
2002年 | 10篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1972年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有292条查询结果,搜索用时 328 毫秒
101.
Giuliana Maddalena François Delmotte Piero Attilio Bianco Gabriella De Lorenzis Silvia Laura Toffolatti 《The Annals of applied biology》2020,176(3):257-267
Downy mildew, caused by the Oomycete Plasmopara viticola, is one of the most important diseases affecting the Eurasian grapevine, Vitis vinifera. The pathogen originated in Northern America and its presence was signalled for the first time into Europe in 1878. In this study, the genetic variability and structure of Italian P. viticola population was investigated by genotyping 106 P. viticola strains belonging to 12 different regions, at 31 microsatellite markers. As a result of the high percentage of missing data, 96 strains and 19 loci were retained for the data analysis. The overall Italian population presents absence of clones, evidence of sexual and asexual reproduction and a low genetic diversity, as expected for an introduced pathogen, but a slightly higher genetic diversity than that found in other European populations, based on allelic diversity at the investigated microsatellite loci. Out of 19 loci, half shows deviation from Hardy–Weinberg equilibrium and, indeed, structure analysis indicates the presence of two separate genetic clusters, with little but significantly different distribution according to geography (west–east gradient) and climatic conditions. Overall, the analysis of the P. viticola population, 140 years after its appearance in Italy, provides indication on the pathogen adaptability. This should be taken into consideration in the future for preserving the durability of disease resistant varieties in open field. In this view, all the disease control methods available should be integrated in order to reduce the selection of pathogen strains able to overcome plant resistance. 相似文献
102.
Loredana Prestinicola Clara Boglione Pavlos Makridis Attilio Spanò Valentina Rimatori Elisa Palamara Michele Scardi Stefano Cataudella 《PloS one》2013,8(2)
In this paper, 981 reared juveniles of gilthead seabream (Sparus aurata) were analysed, 721 of which were from a commercial hatchery located in Northern Italy (Venice, Italy) and 260 from the Hellenic Center for Marine Research (Crete, Greece). These individuals were from 4 different egg batches, for a total of 10 different lots. Each egg batch was split into two lots after hatching, and reared with two different methodologies: intensive and semi-intensive. All fish were subjected to processing for skeletal anomaly and meristic count analysis. The aims involved: (1) quantitatively and qualitatively analyzing whether differences in skeletal elements arise between siblings and, if so, what they are; (2) investigating if any skeletal bone tissue/ossification is specifically affected by changing environmental rearing conditions; and (3) contributing to the identification of the best practices for gilthead seabream larval rearing in order to lower the deformity rates, without selections. The results obtained in this study highlighted that: i) in all the semi-intensive lots, the bones having intramembranous ossification showed a consistently lower incidence of anomalies; ii) the same clear pattern was not observed in the skeletal elements whose ossification process requires a cartilaginous precursor. It is thus possible to ameliorate the morphological quality (by reducing the incidence of severe skeletal anomalies and the variability in meristic counts of dermal bones) of reared seabream juveniles by lowering the stocking densities (maximum 16 larvae/L) and increasing the volume of the hatchery rearing tanks (minimum 40 m3). Feeding larvae with a wide variety of live (wild) preys seems further to improve juvenile skeletal quality. Additionally, analysis of the morphological quality of juveniles reared under two different semi-intensive conditions, Mesocosm and Large Volumes, highlighted a somewhat greater capacity of Large Volumes to significantly augment the gap with siblings reared in intensive (conventional) modality. 相似文献
103.
104.
105.
Rodrigues MS Ferreira LS Converti A Sato S de Carvalho JC 《Bioresource technology》2011,102(11):6587-6592
Previous work demonstrated that a mixture of NH4Cl and KNO3 as nitrogen source was beneficial to fed-batch Arthrospira (Spirulina) platensis cultivation, in terms of either lower costs or higher cell concentration. On the basis of those results, this study focused on the use of a cheaper nitrogen source mixture, namely (NH4)2SO4 plus NaNO3, varying the ammonium feeding time (T = 7-15 days), either controlling the pH by CO2 addition or not. A. platensis was cultivated in mini-tanks at 30 °C, 156 μmol photons m−2 s−1, and starting cell concentration of 400 mg L−1, on a modified Schlösser medium. T = 13 days under pH control were selected as optimum conditions, ensuring the best results in terms of biomass production (maximum cell concentration of 2911 mg L−1, cell productivity of 179 mg L−1 d−1 and specific growth rate of 0.77 d−1) and satisfactory protein and lipid contents (around 30% each). 相似文献
106.
Bezerra RP Montoya EY Sato S Perego P de Carvalho JC Converti A 《Bioresource technology》2011,102(3):3215-3219
Semicontinuous cultures were carried out at different dilution rates (D) and light intensities (I) to determine the maximum productivity of Arthrospira platensis cultivated in helicoidal photobioreactor up to the achievement of pseudo-steady-state conditions. At I=108 μmol photons m(-2) s(-1), the semicontinuous regime ensured the highest values of maximum cell concentration (X(m)=5772±113 mg L(-1)) and productivity (P(XS)=1319±25 mg L(-1) d(-1)) at the lowest (D=0.1 day(-1)) and the highest (D=0.3 day(-1)) dilution rates, respectively. A kinetic model derived from that of Monod was proposed to determine the relationship between the product of light intensity to dilution rate (ID) and the cell productivity, which were shown to exert a combined influence on this parameter. This result put into evidence that pseudo-steady-state conditions could be modified according to circumstances, conveniently varying one or other of the two independent variables. 相似文献
107.
Dario Braga Elena Ferracini Adele Ferrero Alberto Ripamonti David A. Brant Gregory S. Buliga Attilio Cesàro 《International journal of biological macromolecules》1985,7(3):161-166
An investigation of the small-angle X-ray scattering properties of aqueous solutions of an amylose derivative has been carried out. Experiments have been conducted in stable and fairly concentrated polymer solutions (up to 3.2%) by using a slightly substituted carboxymethylamylose having a degree of substitution of 0.08. Scattering intensities display a maximum in the low angle range which prevents extrapolation of the angular dependence to zero angle. Data obtained in the range of scattering vector 0.01<η<0.1Å?1 yield 8 Å as the radius of gyration of the chain cross-section and 140 dalton Å?1 as the mass per unit length. These results are analysed in terms of the current model of amylose solution conformation and compared with the theoretical calculations of the Debye scattering function of the isolated chain. 相似文献
108.
Rigotti A 《Molecular aspects of medicine》2007,28(5-6):423-436
Vitamin E is one of the most abundant lipid-soluble antioxidant agents found in plasma and cells of higher mammals. The uptake, transport and tissue delivery of -tocopherol, a key vitamin E form, involves molecular, biochemical, and cellular processes closely related to overall lipid and lipoprotein homeostasis. This review highlights recent findings that have led to a better understanding of vitamin E transport, including intestinal absorption, hepatic transport, and cellular uptake of -tocopherol in vivo. This new information may be critical for manipulation of vitamin E homeostasis in a variety of oxidative stress-related disease conditions in humans. 相似文献
109.
Boumendjel A Macalou S Ahmed-Belkacem A Blanc M Di Pietro A 《Bioorganic & medicinal chemistry》2007,15(8):2892-2897
The breast cancer resistance protein (BCRP, ABCG2) is among the latest discovered ABC proteins to be involved in MDR phenotype and for which only few inhibitors are known. In continuing our program aimed at discovering efficient multidrug resistance modulators, we conceived and synthesized new acridones as ABCG2 inhibitors. The design of target molecules was based on earlier results dealing with ABCG2 inhibition with flavone and chromone derivatives. The human wild-type (R482) ABCG2-transfected cells were used for rational screening of inhibitory acridones. The synthesis of target compounds, the inhibitory activity against ABCG2, and structure-activity relationships are described. One of the acridones was even more potent than the reference inhibitor, GF120918, as shown by its ability to inhibit mitoxantrone efflux. 相似文献
110.
Influence of pH, temperature, and urea molar flowrate on Arthrospira platensis fed-batch cultivation: a kinetic and thermodynamic approach 总被引:1,自引:0,他引:1
Sánchez-Luna LD Bezerra RP Matsudo MC Sato S Converti A de Carvalho JC 《Biotechnology and bioengineering》2007,96(4):702-711
Arthrospira platensis was cultivated photoautotrophically at 6.0 klux light intensity in 5.0-L open tanks, using a mineral medium containing urea as nitrogen source. Fed-batch experiments were performed at constant flowrate. A central composite factorial design combined to response surface methodology (RSM) was utilized to determine the relationship between the selected response variables (cell concentration after 10 days, X(m), cell productivity, P(X), and nitrogen-to-cell conversion factor, Y(X/N)) and codified values of the independent variables (pH, temperature, T, and urea flowrate, K). By applying the quadratic regression analysis, the equations describing the behaviors of these responses as simultaneous functions of the selected independent variables were determined, and the conditions for X(m) and P(X) optimization were estimated (pH 9.5, T = 29 degrees C, and K = 0.551 mM/day). The experimental data obtained under these conditions (X(m) = 749 mg/L; P(X) = 69.9 mg/L.day) were very close to the estimated ones (X(m) = 721 mg/L; P(X) = 67.1 mg/L.day). Additional cultivations were carried out under the above best conditions of pH control and urea flowrate at variable temperature. Consistently with the results of RSM, the best growth temperature was 29 degrees C. The maximum specific growth rates at different temperatures were used to estimate the thermodynamic parameters of growth (DeltaH* = 59.3 kJ/mol; DeltaS* = -0.147 kJ/mol.K; DeltaG* = 103 kJ/mol) and its thermal inactivation (DeltaH(D) (o) = 72.0 kJ/mol; DeltaS(D) (o) = 0.144 kJ/mol.K; DeltaG(D) (o) = 29.1 kJ/mol). 相似文献