全文获取类型
收费全文 | 169篇 |
免费 | 9篇 |
国内免费 | 1篇 |
专业分类
林业 | 40篇 |
农学 | 8篇 |
基础科学 | 2篇 |
32篇 | |
综合类 | 10篇 |
农作物 | 5篇 |
水产渔业 | 11篇 |
畜牧兽医 | 54篇 |
园艺 | 7篇 |
植物保护 | 10篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 10篇 |
2020年 | 10篇 |
2019年 | 13篇 |
2018年 | 10篇 |
2017年 | 8篇 |
2016年 | 11篇 |
2015年 | 10篇 |
2014年 | 7篇 |
2013年 | 14篇 |
2012年 | 13篇 |
2011年 | 13篇 |
2010年 | 7篇 |
2009年 | 3篇 |
2008年 | 10篇 |
2007年 | 8篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1999年 | 1篇 |
1997年 | 1篇 |
1993年 | 2篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1975年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有179条查询结果,搜索用时 15 毫秒
91.
92.
The effect of flow on the competition between the alien racer goby and native European bullhead 下载免费PDF全文
Łukasz Jermacz Jarosław Kobak Anna Dzierżyńska Tomasz Kakareko 《Ecology of Freshwater Fish》2015,24(3):467-477
The racer goby is an invasive Ponto‐Caspian fish spreading throughout Europe. They threaten a native species of similar biology, the European bullhead, by displacing them from shelters. These shelters are necessary for reproduction as well as for protection against predators and hydrodynamic forces. However, abiotic conditions may strongly modify the outcome of an interspecific competition in the wild. Nevertheless, little is known of the effect of flow velocity on the competition between these rheophilic species, although this factor is crucial for their distribution in the field. We video‐recorded fish behaviour for 2 h in single‐species and mixed‐species pairs in the presence of single shelters at three flow velocities: 0, 10 (a velocity preferred by the racer goby) and 30 cm·s?1 (a velocity greater than preferred by the racer goby) to determine whether the invader can deprive the native species of its shelter. At the flow of 0 and 10 cm·s?1, the racer goby exhibited aggressive behaviour towards bullhead, and this restricted the time spent by the bullhead in the shelter. Moreover, although the flow of 30 cm·s?1 inhibited racer goby aggression, the time spent by the bullhead in the shelter in interspecific competition was still reduced when compared to intraspecific controls. Our results suggest that under natural conditions, the racer goby displace bullheads from their shelters even at flow velocities greater than optimal for the racer goby. 相似文献
93.
94.
Acute-phase proteins,cortisol and haematological parameters in ewes during the periparturient period
Monika Greguła-Kania Urszula Kosior-Korzecka Krzysztof Patkowski Edyta Juszczuk-Kubiak Michał Plewik Tomasz Maria Gruszecki 《Reproduction in domestic animals》2020,55(3):393-400
Numerous subclinical diseases in sheep occur in the periparturient period and involve inflammatory processes; therefore, determining markers, such as acute-phase proteins (APPs), can allow an early diagnosis. Therefore, the objective of the present study was to assess changes in the plasma concentration of APPs and cortisol in clinically healthy ewes in the periparturient period for use in future studies. At the same time, haematological parameters were monitored. We showed that plasma APPs and cortisol concentrations were significantly higher in pregnant ewes than before insemination. A gradual increase in the SAA concentration was observed from the 14th day before to the day of parturition, while Hp was reduced from 2 weeks before up to 2 weeks after delivery. A significant increase in the Fb concentration was detected from the 14th day before to the 1st week after delivery. The cortisol concentration did not undergo significant changes in the periparturient period. We found an increase in the SAA and Fb concentrations and decrease in Hp in the periparturient period. The direction of the change in APPs of healthy ewes in the current study may be related to their distinct regulatory mechanisms during pregnancy. The APPs are usually altered during infection, inflammation, neoplasia, stress and trauma; therefore, knowing their reference values could help lead to an early diagnosis of subclinical forms of some diseases and pregnancy complications in ewes. The haematological analysis showed that ewes in late pregnancy and postpartum compared to dry period were under metabolic stress related to pregnancy and lactation. 相似文献
95.
Tomasz Szmatoła Igor Jasielczuk Ewelina Semik-Gurgul Magdalena Szyndler-Nędza Tadeusz Blicharski Karolina Szulc Ewa Skrzypczak Artur Gurgul 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2020,137(6):571-580
Runs of homozygosity (ROH) are continuous segments of the genome that arose as a result of inbreeding, resulting in the inheritance of identical haplotypes from both parents who shared a common ancestor. In the present study, we performed a detailed characterization and comparison of ROH in four pig breeds, including intensively selected Polish Landrace as well as native unselected animals of Puławska and two Złotnicka breeds (White and Spotted). We used a medium-density PorcineSNP60 BeadChip assay (Illumina) and cgaTOH software to detect ROH covering a minimum of 30 adjacent SNPs and maintaining a size over 1 Mb. By analysing ROH distribution and frequency across the genome, we also identified genomic regions with high ROH frequency (so-called “ROH hotspots”). The obtained results showed that the analysed conserved breeds were characterized by a higher ROH span and higher ROH-based inbreeding coefficients (FROH), which likely result from past population bottlenecks, increasing the overall inbreeding level within these populations. The analysis of ROH distribution across the genomes revealed the presence of both shared and breed-specific ROH hotspots. These hotspots, presumably representing genome regions under selection, overlapped with a variety of genes associated with processes connected with immune system functioning, reproduction, glucose homeostasis and metabolism. The genome regions with ROH hotspots overlapping in all analysed populations, located on SSC4 (51.9–55.9 Mb) and 13 (92.6–97.8 Mb), covered thirty-one different genes, including MMP16, SLC7A13, ATP6V0D2, CNGB3, WWiP1, RiMDN1 and CPNE3. These genes are primarily associated with biological regulation and metabolism, processes that could be responsible for the variety of the selected production and functional features. 相似文献
96.
Agnieszka Białek Małgorzata Białek Małgorzata Czerwonka Tomasz Lepionka Natalia Tytz Karolina Kucharczyk Elżbieta Tober Karol Kaszperuk Teresa Banaszkiewicz 《Journal of animal physiology and animal nutrition》2021,105(3):520-534
The aim of present study was to determine whether chickens’ (broilers Ross 308, n = 180, sex ratio 1:1) diet modification with different doses of grape or pomegranate seed oil will favourable change fatty acids and cholesterol content in selected giblets (liver and heart) or wastes (adipose tissue). It was also verify whether generated changes would make the giblets and wastes more valuable as dietary components or by-products for food industry. From 22 to 42 day of life, five diets were administered to chickens. Control grower diet (CON) contained 5% of soy oil, whereas in the experimental grower diets part of soy oil (1.5% or 2%) was replaced with specific amount of grape or pomegranate seed oil (GRAP 1.5; GRAP 2.0; POM 1.5; POM 2.0 respectively). Fatty acids and cholesterol content were determined with gas chromatography with flame-ionization detection. Pomegranate seed oil improved fatty acids profile more favourably than grape seed oil, which makes it a valuable additive in chickens’ feeding. Abdominal fat of pomegranate seed oil supplemented chickens appeared to be the richest sources of rumenic acid and n3 polyunsaturated fatty acids, which allows to suggest its use in manufacturing of meat products to obtain foodstuffs rich in those essential nutrients. In principal component analysis (PCA), two principal components: PC1 and PC2, which were enough to explain 29.91% of variance of initial variables, allowed to a good separation of chickens fed with both doses of pomegranate seed oil from animals from control and grape seed oil fed groups. Because poultry addresses all nutritional, institutional and consumer requirements, enrichment of giblets in rumenic acid by pomegranate seed oil incorporation into chickens’ diet may provide a valuable dietary source of bioactive fatty acids for consumers, especially of low-income countries. 相似文献
97.
Ryszard Oleszczuk Klaus Bohne Jan Szatylowicz Tomasz Brandyk Tomasz Gnatowski 《植物养料与土壤学杂志》2003,166(2):220-224
The shrinkage of the peat soils that accompanies the soil moisture changes is an important feature of such soils and has strong influence on their physical attributes and soil water management. The relationships between soil moisture and volume are often described using shrinkage characteristic curves by relating void ratio (volume of voids per unit volume of solids) to moisture ratio (volume of water per volume of solids). For conversion of soil volume changes into cracks volume and subsidence, a dimensionless shrinkage geometry factor is used. The paper presents results of volumetric shrinkage behavior and the geometry factor at various loads in sedge and alder peat soils. The measurements were conducted on undisturbed soil samples without applying a load and with loads corresponding to field overburden. The shape of the shrinkage characteristics of such soils were completely different from those of clay soils. The application of loads did not significantly influence the shrinkage characteristics curve. The applied load strongly influenced on relationship between shrinkage geometry factor and the moisture ratio, showing higher values of subsidence and lower values of crack volume in comparison with unloaded conditions. 相似文献
98.
Borkowski T Szymusiak H Gliszczyńska-Rwigło A Rietjens IM Tyrakowska B 《Journal of agricultural and food chemistry》2005,53(14):5526-5534
The radical scavenging capacity of red wine anthocyanins was quantified by the so-called TEAC assay with special emphasis on the influence of pH and conjugation on this activity. The pH appears to be a dominant factor in the radical scavenging capacity of wine anthocyanins, with higher pH values increasing this capacity significantly. On the basis of the pKa values for deprotonation and theoretical calculations, it could be concluded that the effect is due to an increase in intrinsic radical scavenging capacity upon deprotonation. The data also reveal that the reduction in radical scavenging activity of anthocyanins upon their conjugation can, at least in part, be ascribed to an increase in pKa values upon conjugation. Altogether, the results obtained provide molecular insight into factors that influence radical scavenging potential of anthocyanins and reveal that the radical scavenging-mediated supposed beneficial health effects of these wine pigments will be influenced by the pH of the surrounding matrix or tissue. 相似文献
99.
100.
Jan Holeksa Milan Saniga Jerzy Szwagrzyk Tomasz Dziedzic Stanisław Ferenc Maciej Wodka 《European Journal of Forest Research》2007,126(2):303-313
The structure of natural subalpine spruce forest in the Zadná Pol’ana massif of the Western Carpathians was analysed. We focused
on the variability of different aspects of stand structure, tree decay and regeneration processes in altitudinal gradient.
We used systematic sampling, covering an area of 2 km2, to detect even subtle changes in stand structure within one forest type over a range of less than 200 m in elevation. Mean
stand density was 290 trees (>7 cm DBH) per hectare, average basal area was 41 m2 ha−1, and the volume accumulation in living trees amounted to 500 m3/ha−1. Stand volume decreased by more than 50% between 1,260 and 1,434 m a.s.l. This means for an increase of altitude of 100 m
that stand volume decreased by nearly 200 m3. Neither stand density nor basal area was related to elevation. Maximum tree height was strongly correlated to elevation,
and it decreased on average by 6 m for each 100 m increment of altitude. No significant changes in the maximum spruce diameter
were recorded in relation to the elevation gradient. Spatial distribution of trees was biased toward regularity at lower altitudes.
Tree clustering increased with increasing altitude. The stock of coarse woody debris (CWD) decreased slightly along the altitudinal
gradient, but changes were not significant. Density of spruce saplings and their number growing on CWD significantly increased
across the elevation gradient. Despite the fact that the analysed forest tract was relatively large, highly variable in respect
to environmental factors, and that stand volume, spatial structure, and tree height displayed strong variability along the
elevation gradient, the diameter structure of stands and regeneration measures were uniform. Our results suggest that the
recruitment of new trees in the Zadná Pol’ana subalpine spruce forest is not temporally continuous even at a scale of several
square kilometres. 相似文献