全文获取类型
收费全文 | 358篇 |
免费 | 33篇 |
专业分类
林业 | 32篇 |
农学 | 11篇 |
基础科学 | 2篇 |
88篇 | |
综合类 | 15篇 |
农作物 | 21篇 |
水产渔业 | 77篇 |
畜牧兽医 | 108篇 |
园艺 | 13篇 |
植物保护 | 24篇 |
出版年
2024年 | 2篇 |
2023年 | 1篇 |
2022年 | 7篇 |
2021年 | 18篇 |
2020年 | 28篇 |
2019年 | 15篇 |
2018年 | 20篇 |
2017年 | 12篇 |
2016年 | 17篇 |
2015年 | 15篇 |
2014年 | 13篇 |
2013年 | 27篇 |
2012年 | 23篇 |
2011年 | 36篇 |
2010年 | 24篇 |
2009年 | 13篇 |
2008年 | 23篇 |
2007年 | 14篇 |
2006年 | 21篇 |
2005年 | 8篇 |
2004年 | 14篇 |
2003年 | 11篇 |
2002年 | 9篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1981年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有391条查询结果,搜索用时 12 毫秒
111.
Bonoli-Carbognin M Cerretani L Bendini A Almajano MP Gordon MH 《Journal of agricultural and food chemistry》2008,56(16):7076-7081
Virgin olive oil is valued for its flavor, but unacceptable off-flavors may develop on storage in food products containing this oil due to oxidation. The oxidative stability of oil-in-water emulsions containing bovine serum albumin (BSA) and virgin olive oil phenolic compounds was studied. Four oil-in-water emulsions with and without BSA and phenols isolated from virgin olive oil were prepared. These model systems were stored at 60 degrees C to speed up lipid oxidation. Primary and secondary oxidation products were monitored every three days. Peroxide values and conjugated diene contents were determined as measures of the primary oxidation products. p-Anisidine values and volatile compounds were determined as measures of the secondary oxidation products. This latter determination was carried out by headspace solid-phase microextraction coupled with gas chromatography. Although olive oil phenolic compounds and BSA contributed some antioxidant activity when present as individual additives, the combination of BSA with phenols in an emulsion showed 58-127% synergy, depending on which analytical method was used in the calculation. The emulsion containing phenolic compounds and BSA showed a low level of deterioration after 45 days of storage at 60 degrees C. 相似文献
112.
Isabella Buttino Adrianna Ianora Silvia Buono Valentina Vitiello Maria G Malzone Cira Rico Antonio L Langellotti Giovanni Sansone Lorenzo Gennari Antonio Miralto 《Aquaculture Research》2012,43(2):247-259
A pilot re‐circulating system was used for the cultivation of two Mediterranean calanoid copepods: Temora stylifera and Centropages typicus. The system automatically concentrated the naupliar and copepodite stages. Temora stylifera was fed the flagellate Rhodomonas baltica or Prorocentrum minimum, whereas C. typicus was fed with a mixture of R. baltica or P. minimum and Tetraselmis suecica. Both copepods also received Isochrysis galbana. After 21 days, the T. stylifera population increased 26‐fold, reaching a density of 38 000 individuals, mostly represented by nauplii (88%). The maximum density recorded was 380 ind. L?1, with a production of 370 nauplii L?1. On average, the egg hatching success for this copepod during the rearing period was 54%, with the highest viability in April and May (>75%). The C. typicus population increased more than 10‐fold after 7 weeks of rearing, reaching a density of 123 000 individuals, mainly represented by nauplii (>90%). The highest naupliar production was 100 ind. L?1, with a mean egg hatching success of 68%. This system may be useful to produce nauplii and copepodite stages to be used as live, alternative or complementary food for fish larvae or to provide a ready source of organisms for physiological and bioassay studies. 相似文献
113.
C. Cattano G. Turco M. Di Lorenzo M. Gristina G. Visconti M. Milazzo 《水产资源保护:海洋与淡水生态系统》2021,31(6):1420-1428
- An aggregation of sandbar sharks Carcharhinus plumbeus occurs every summer around the remote uninhabited islet of Lampione (Pelagie Islands Marine Protected Area, south-western Mediterranean Sea), attracting an increasing number of tourists for a shark watching experience.
- Despite the ecological and socio-economic importance of this rare occurrence in Mediterranean waters, there is a lack of scientific data and lack of information as to the potential impact of tourist activities on the presence and behaviour of this shark species.
- Using baited underwater videos, this study provides the first assessment of this shark aggregation, as well as a preliminary evaluation of the potential effects that boating and diving activities may have on sandbar sharks during two different periods within the tourism season (July and September 2019).
- Overall, 241 sandbar shark sightings (with up to five individuals together) were recorded in July, whereas there were only six sightings in September. The average MaxN was 1.18 hr−1 (±0.21 hr−1 SE) and 0.22 hr−1 (±0.10 hr−1 SE) individuals in July and September respectively. Higher frequentation levels of divers and boats significantly reduced the number of shark sightings at the aggregation site.
- This study emphasizes the need for further investigations on Mediterranean shark aggregations and the implementation of specific conservation measures, such as an increase of protection level in Lampione and better enforcement, aside from strategies that promote sustainable tourism, including restrictions on the number of boats and divers’ visits per day. In the meantime, a precautionary approach aimed at regulating the interactions between tourists and sharks should be implemented through the application of a self-regulatory code of conduct for divers when sharks aggregate around the island.
114.
Sara Ferrando Lorenzo Gallus Chiara Gambardella Emiliano Marchesotti Silvia Ravera Valeria Franceschini Maria Angela Masini 《Fish physiology and biochemistry》2014,40(6):1793-1800
Among vertebrates, the physiologically uremic Chondrichthyes are the only class which are not presenting the ciliated olfactory receptor neurons in the olfactory neuroepithelium. The only sequenced genome for this class revealed only three olfactory receptor genes and the immunohistochemical detection of G protein alpha subunit typically coupled to the olfactory receptors (Gαolf) failed in different species. Chronic renal disease can represent a cause of olfactory impairment in human. In this context, our present study focused on investigating potential effects of high urea concentration on the olfactory epithelium of vertebrates. Larvae of the teleost fish Danio rerio were exposed to urea in order to assess the effects on the olfactory signal transduction; in particular on both the olfactory receptors and the Gαolf. The endocytosis of neutral red dye in the olfactory mucosa was detected in control and urea-exposed larvae. The amount of neutral red dye uptake was used as a marker of binding and internalization of the Gαolf. The neutral red dye endocytosis was not affected by urea exposure, hence suggesting that the presence of the Gαolf and their binding to the odorants are not affected by urea treatment, either. The presence and distribution of Gαolf were investigated in the olfactory epithelium of control and urea-exposed larvae, using a commercial antibody. The immunoreactivity was increased after urea treatment, suggesting an effect of urea on the expression or degradation of this G protein alpha subunit. 相似文献
115.
Martín MV Almansa E Cejas JR Bolaños A Jerez S Lorenzo A 《Fish physiology and biochemistry》2011,37(4):935-949
A feeding experiment was carried out to determine the effect of a diet lacking n-3 and n-6 highly unsaturated fatty acids
(HUFA) on lipid and fatty acid content in intestine and gills of male gilthead seabream (Sparus aurata L.) broodstock at different stages of the reproductive cycle: November (pre-spermatogenesis), March (spermatogenesis), and
June (post-spermatogenesis). For this purpose, gilthead seabream broodstock were fed either a control diet (C) or an n-3 and
n-6 HUFA-deficient diet (D). The results showed no changes in fatty acid content of polar lipids of intestine and gills from
fish fed diet C at different stages of the reproductive cycle. However, significant changes were observed in the fatty acid
content of neutral lipids in intestine but not in gills in this group. Thus, between November and March, saturates and n-3
HUFA decreased while monoenes increased. In June, the contents of these fatty acids had returned to their initial values (November).
Moreover, in fish fed diet D, the fatty acid content of neutral lipid changed in both intestine and gills. In intestine NL,
a decrease in saturates and n-3 HUFA and an increment in monoenes were observed from November to June. In gills, a decrease
was also observed in n-3 HUFA from NL along the cycle. Nevertheless, n-6 HUFA content remained unchanged. These results show
both tissue specificity in seasonal mobilization of fatty acids linked to reproductive processes and the influence of dietary
fatty acids on body composition. 相似文献
116.
Pedro M. Domingues Lorenzo Marquez Nelda López Carlos Rosas 《Aquaculture International》2009,17(3):283-299
The diet of frozen grass shrimp (P. varians) was compared to similar grass shrimp that had suffered either boiling, drying at 60°C, or freeze-drying by lyophilization
at −40°C. In experiment 1, cuttlefish fed the frozen shrimp were significantly larger (P < 0.05) at the end of 10 days and at the end of the experiment, compared with those fed the boiled or dried shrimp. Growth
rates were also higher for cuttlefish fed the frozen shrimp, compared with the remaining two. Growth rates were also higher
for cuttlefish fed the frozen shrimp, compared with the remaining two. In experiment 2, there were no differences in weight
(P > 0.05) between cuttlefish fed the frozen or the freeze-dried shrimp, whereas cuttlefish fed the dried shrimp were smaller
at the end of the experiment. Growth rates of cuttlefish fed the dried shrimp were lower, compared with those for cuttlefish
fed the frozen and freeze-dried shrimp, with no significant differences (P > 0.05) between them. Cuttlefish fed freeze-dried and frozen shrimp showed a higher trypsin activity compared to animals
fed boiled and dry (60°C) shrimp. A higher proportion of absorbed energy was channelled into biomass production in animals
fed frozen and freeze-dried shrimp (56% and 43%, respectively) than for animals fed oven-dried (60°C) or boiled shrimp. The
heat treatment suffered by the shrimp, either dry or wet, negatively affected diet quality, probably due to denaturation,
and loss (by boiling) of proteins and amino acids. Additionally, the heating processes may have oxidized the lipids to a large
extent, contributing to the loss of the polar lipids (polyunsaturated fatty acids), which are essential for cephalopods as
for other organisms. Freeze-drying by lyophilization (negative temperatures) did not affect the nutritional quality of the
shrimp. 相似文献
117.
Juan Zamora‐Sillero Mateus Tavares Kütter Marcelo Borges Tesser Jos María Monserrat Carlos Prentice 《Aquaculture Nutrition》2019,25(1):110-118
A feeding trial was conducted to evaluate the effect of dietary protein hydrolysates from common carp (Cyprinus carpio) by‐products on the antioxidant status of zebrafish (Danio rerio). Common carp by‐product was hydrolysed using Alcalase to a degree of hydrolysis of 15%. The zebrafish were fed for 44 days with four different diets with increasing levels of carp by‐product hydrolysates (CBH0: 0 g/kg; CBH25: 25 g/kg; CBH50: 50 g/kg; CBH100: 100 g/kg). The gills, muscle and brain were dissected at the end of the feeding trial in order to evaluate the total antioxidant capacity against peroxyl radicals (ACAP) and lipid peroxidation (TBARS). Although total antioxidant capacity did not show differences in muscle (p > 0.05), lipid peroxidation was reduced in the muscle of fish fed the CBH50 diet. Brain lipid peroxidation showed a significant reduction (p < 0.05) in all groups when compared with the control diet CBH0. Antioxidant properties of protein hydrolysates indicate their potential as nutraceuticals since (a) a reduction in muscle lipid peroxidation was verified, implying that their use could enhance the quality and shelf life of fish fillets; and (b) a decrease in brain lipid peroxidation was registered, highlighting the potential use of fish protein hydrolysates for the prevention of neurodegenerative diseases. 相似文献
118.
Daniel Pinto Lucas Pellegrin Lilian Fiori Nitz Sílvio Teixeira da Costa Jos Maria Monserrat Luciano Garcia 《Aquaculture Research》2019,50(10):3017-3027
In this study, the influence of temperature variation on the blood and oxidative stress parameters of pacu Piaractus mesopotamicus juveniles was evaluated. Fish were subjected to gradual changes of temperature, over 5 days, by 24°C until reaching to experimental temperatures 18, 21, 24 (control), 27 and 30°C. There were significant differences (p < .05) in glucose and lactate of blood in both the haematological relationships and oxidative stress parameters. Glucose levels increased at 30°C and decreased at 21°C. Lactate levels were highest at 18°C. While the haematocrit was higher at all altered temperatures, haemoglobin levels decreased at 21°C and increased at 30°C, causing alterations in haematimetric indices. In the liver, glutathione‐S‐transferase (GST) activity was reduced at 18°C while antioxidant capacity against peroxyl radicals (ACAP) was highest at 30°C. Thiobarbituric acid reactive substances (TBARS) increased at 18, 21 and 27°C. In the muscle, ACAP decreased at 27 and 30°C and TBARS increased at 30°C. The results indicate that the species shows sensitivity to temperature variations. Accordingly, we conclude that with short‐term temperature variations >3°C, it is possible to induce higher alterations in the observed parameters in pacu juveniles. 相似文献
119.
Diogo S. M. Samia Eduardo Bessa Daniel T. Blumstein Jos A. C. C. Nunes Ernesto Azzurro Lorenzo Morroni Valerio Sbragaglia Fraser A. Januchowski‐Hartley Benjamin Geffroy 《Fish and Fisheries》2019,20(5):817-829
In an increasingly anthropic world, humans have profound impacts on the distribution and behaviour of marine fishes. The increased human presence has modified fishes’ antipredator behavioural responses, and consequently flight decisions, as a function of their changed perceptions of risk. Understanding how fish react to human presence can help identify the most vulnerable functional groups/species and estimate impacts caused by human disturbance. Shoal and body size are known to influence fish flight initiation distance (FID; the distance between the predator and prey when the prey begins to escape); however, few studies attempt to test the moderators of these relationships. Here, we present a comprehensive meta‐analysis evaluating FID of fish in response to human presence. Specifically, we investigated six candidate moderators that could influence the relationship between FID with shoal and body size. Our results showed that individual fish size was strongly and positively correlated with FID and the most important moderator that explained the variance in individual body size‐FID relationship was shoaling behaviour. However, and somehow surprisingly, we detected no significant relationship between shoal size and FID. We discuss how these results can inform the development of fish conservation strategies and ultimately assist in the management of marine protected areas. 相似文献
120.
Reproductive efficiency of the largest individuals and a random group of broodstock of crayfish Procambarus acanthophorus was measured using two commercial shrimp feeds, Feed 1 (F1) broodstocks (40%/9% protein/lipids) and Feed 2 (F2) growth-out (35%/7% protein/lipids). An experimental design of four treatments with two replicates was used. Females were labeled with elastomers to determine the time between spawning and number of offspring per treatment. The number of ovigerous females in the largest individuals fed F2 (58) was significantly higher than ovigerous females in the control group fed F1 (30).The number of young crayfish per female produced in the largest individuals (173 ± 71.6) treatment was significantly higher than the crayfish produced in the control group (86.6 ± 42.6). The average interval between spawns, regardless of diet, in the largest females was 2.9 months and 2.6 months in control group females. 相似文献