全文获取类型
收费全文 | 108篇 |
免费 | 8篇 |
专业分类
林业 | 10篇 |
农学 | 5篇 |
35篇 | |
综合类 | 6篇 |
农作物 | 7篇 |
水产渔业 | 17篇 |
畜牧兽医 | 24篇 |
园艺 | 4篇 |
植物保护 | 8篇 |
出版年
2022年 | 1篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 8篇 |
2017年 | 9篇 |
2016年 | 6篇 |
2015年 | 1篇 |
2014年 | 5篇 |
2013年 | 6篇 |
2012年 | 8篇 |
2011年 | 7篇 |
2010年 | 5篇 |
2009年 | 1篇 |
2008年 | 6篇 |
2007年 | 9篇 |
2006年 | 9篇 |
2005年 | 8篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2000年 | 2篇 |
1997年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1973年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有116条查询结果,搜索用时 31 毫秒
81.
Sadowski A 《Science (New York, N.Y.)》1960,132(3429):736-737
The radarscope photographic sequence, by far the best example on record, reveals a spirally banded structure about 10 miles in diameter which is similar to spiral bands of hurricanes ranging as far as 250 miles and to the banded cloud structure of well-developed storms of 1000 miles as photographed by Tiros I. 相似文献
82.
Tomasz Grabowski Artur Burmaczuk Rafa Derlacz Tadeusz Stefaniak Anna Rzsa Jacek Borkowski 《Journal of veterinary science (Suw?n-si, Korea)》2021,22(5)
BackgroundDue to multiple similarities in the structure and physiology of human and pig skin, the pig model is extremely useful for biological drug testing after subcutaneous administration. Knowledge of the differences between subcutaneous injection sites could have a significant impact on the absorption phase and pharmacokinetic profiles of biological drugs.ObjectivesThis study aimed to analyze the impact of administration site on pharmacokinetics and selected biochemical and hematological parameters after a single subcutaneous administration of ustekinumab in pigs. Drug concentrations in blood plasma were analyzed by enzyme-linked immunosorbent assay. Pharmacokinetic analyses were performed based on raw data using Phoenix WinNonlin 8.1 software and ThothPro v 4.1.MethodsThe study included 12 healthy, female, large white piglets. Each group received a single dose of ustekinumab given as a 1 mg/kg subcutaneous injection into the internal part of the inguinal fold or the external part of the inguinal fold.ResultsThe differences in absorption rate between the internal and external parts of the inguinal fold were not significant. However, the time of maximal concentration, clearance, area under the curve calculated between zero and mean residence time and mean residence time between groups were substantially different (p > 0.05). The relative bioavailability after administration of ustekinumab into the external part of the inguinal fold was 40.36% lower than after administration of ustekinumab into the internal part of the inguinal fold.ConclusionsHealthy breeding pigs are a relevant model to study the pharmacokinetic profile of subcutaneously administered ustekinumab. 相似文献
83.
Bogdan Brzeziecki Kamil Bielak Leszek Bolibok Stanisław Drozdowski Jacek Zajączkowski Henryk Żybura 《Annals of Forest Science》2018,75(3):89
? Key message
Long-term strict protection of woodland communities may lead to their compositional simplification and homogenisation.? Context
In the past, it has often been postulated that structures and processes typical for natural forests should be mimicked by silvicultural activities in the case of managed tree stands.? Aims
To determine which features and traits of natural woodland communities (alongside typical old-growth attributes) should be imitated in managed forests, as well as which should not (and for what reasons).? Methods
Tree data from five permanent study plots (of a total area of 15.44 ha) established in 1936 in the core area of the Bia?owie?a National Park (NE Poland) are used to calculate several quantitative indices describing the temporal dynamics (in terms of stand structure and composition) of eight major woodland community types.? Results
Most structural attributes revealed rather high stability over time. In contrast to these, during the observation period, noticeable changes in the composition of particular Bia?owie?a woodland communities have been taking place, related to declining occurrence and reduced roles characteristic for a large number of tree species.? Conclusion
In many ways, natural forests can serve as an important model for managed forest stands. However, in certain circumstances, silvicultural treatments counteracting natural developmental trends may appear to be indispensable, especially when more diverse and stable tree species composition (at a given spatial and temporal scale) is indicated or desirable.84.
Marcin K. Dyderski Anna Gazda Mariusz Hachułka Paweł Horodecki Izabela L. Kałucka Jacek Kamczyc Marek Malicki Remigiusz Pielech Michał Smoczyk Maciej Skorupski Sylwia Wierzcholska Andrzej M. Jagodziński 《Annals of Forest Science》2018,75(4):91
? Key message
Natural regeneration of P. abies (L.) H. Karst. may reach high densities in lower mountain elevations. The highest densities were found in sites with moderate light availability, with low pH, and not near the riverbank. However, age-height classes differed in the predicted magnitude of response, but were consistent in response directions. Mosses and understory species typical of coniferous forests were positively correlated with regeneration density.? Context
Norway spruce Picea abies (L.) H. Karst. in Central Europe is at risk under climate change scenarios, particularly in mountain regions. Little is known about the impact of environmental factors on the natural regeneration of P. abies in low-elevation mountain forests.? Aims
We aimed to assess impacts of distance from the riverbank, soil pH, and light availability on natural P. abies regeneration. We hypothesized that (1) natural P. abies regeneration would depend on light availability and soil pH and (2) there are understory plant species which may indicate the microsites suitable for natural regeneration of P. abies.? Methods
The study was conducted in the Sto?owe Mountains National Park (SW Poland, 600–800 m a.s.l.). We established 160 study plots (25 m2) for natural regeneration, light availability, soil pH, and understory vegetation assessment.? Results
The highest densities of natural regeneration of P. abies were observed in sites with moderate light availability (0.1–0.2 of open sky) and low pH (3.5–4.5), and located relatively far from the riverbank. Cover of 22 understory plant species were correlated with natural P. abies regeneration densities, mostly positively.? Conclusion
Different stages of natural regeneration of P. abies revealed different regeneration niches. Most understory plant species (bryophytes and herbs typical of coniferous forests) do not compete with natural regeneration of P. abies.85.
86.
James C. Mingie J. M. Bowker Michael T. Mengak Jacek P. Siry 《Human Dimensions of Wildlife》2017,22(2):110-125
Hunting lease revenue can be a reliable supplemental income for forest landowners. Although studies have examined factors influencing per acre lease rates, little is known about how various characteristics are capitalized in hunting club dues. The objective of this study was to conduct a hedonic analysis of big game hunting club dues in Georgia, USA using a variety of club-, site-, and location-specific characteristics. To accomplish this objective, multivariate regression analysis was applied to explain variation in hunters’ self-reported big game hunting club dues in 2012. Implicit price was then calculated for each significant covariate. Club size, presence of food plots, and game quality had positive effects on club dues, whereas membership number had a negative effect. These results should be useful for landowners and club lease managers interested in enhancing the marketability of their hunting sites and understanding the effect of management actions. 相似文献
87.
Paulina Robak Magorzata Ogo Adam Lepczyski Agnieszka Herosimczyk Marcin Barszcz Marcin Taciak Jacek Skomia 《Journal of animal physiology and animal nutrition》2019,103(6):1837-1847
The aim of the study was to evaluate the influence of dietary supplementation with inulin extract from chicory root and dried chicory root on the protein profile of the renal cortex and medulla of growing pigs. The experiment was carried out on renal cortex and medulla tissue collected from 24 50‐day‐old PIC x Penarlan P76 crossbred piglets (males). Animals were divided into three dietary groups (n = 8) and fed with a control diet, diet supplemented with 2% inulin extract from chicory root and a diet supplemented with 4% dried chicory root. Kidney samples were collected after 40 days of feeding, and renal cortex and medulla proteins were separated by two‐dimensional electrophoresis. Protein identification was performed using MALDI‐TOF mass spectrometry. The diet supplemented with 2% chicory inulin induced significant expression changes of 20 and 26 protein spots in the renal cortex and medulla respectively. Supplementation with 4% dried chicory root triggered changes in the expression of 44 and 24 proteins in the renal cortex and medulla respectively. Both forms of chicory inulin‐type fructans effectively affected the expression of proteins involved in energy metabolism, heat shock proteins and other chaperones, cytoskeletal and cytoskeleton‐related proteins, as well as other proteins. Additionally, changes in transferrin abundance in both experimental groups suggested the significance of chicory fructan supplementation for iron absorption and bioavailability. In conclusion, 2% inulin extract from chicory root and 4% dried chicory root exerted a similar effect on changes in renal protein expression; however, more pronounced alterations were induced by dried chicory root. Nevertheless, further studies are needed for better understanding the mechanism underlying the effect of chicory inulin‐type fructans and their fermentation end products on the kidneys of growing pigs. 相似文献
88.
Jacek Wawrzykowski Monika Franczyk Marta Kankofer 《Reproduction in domestic animals》2019,54(10):1384-1392
The formation of placenta at the beginning of pregnancy and its separation at parturition require not only deep remodelling of extracellular matrix, which mainly consists of proteins conjugated with sugar moieties, but also the cooperation with cells from both maternal and foetal parts of placenta. The aim of the study was to compare the patterns of selected conjugated proteins with sugar moieties between pregnant and term placenta as well as between released and retained placenta in cows. Placental samples from healthy pregnant cows (3–5 months of pregnancy) were collected at a slaughterhouse (n = 6), and parturient samples were collected during caesarean section at term and retrospectively divided into retained (n = 6) and released (n = 6). The pattern of selected sugar moieties conjugated with proteins was detected by use of lectin blotting with Phaseolus Vulgaris leucoagglutinin, Maackia Amurensis and Sambucus Nigra (Elderberry). The comparison and analysis of obtained band patterns showed differences between their number, molecular weight and abundance related to the intensity of staining. Samples from 3 to 4 months showed similarities, while at the 5th month, clear differences were visible in all 3 lectins, which were used in this study. Samples from retained/released placenta expressed significant differences in PHA‐L and SNA pattern in the foetal part. Obtained results indicate that the development of placenta related to extracellular matrix and accompanying cells from both sides of placenta shows dynamic changes during pregnancy. Moreover, in the case of animals with the retention of foetal membranes the patterns of proteins conjugated with sugar moieties are altered, suggesting that the changes in extracellular matrix metabolism can be involved in the attachment and detachment of the placenta in cows. 相似文献
89.
Follicular growth after antrum formation is determined by follicle-stimulating hormone (FSH). Only two ways are possible for recruited follicles, continuing development or atresia. In gilts, intensive ovarian follicular growth begins between 60 and 100 days of age, and fluctuations of the ovarian morphological status last about 20 days; however, at that time there are no really large follicles. Final follicular development is under luteinising hormone (LH) control; this is why the attainment of puberty is related to an increase in serum oestradiol to a level that causes a preovulatory surge of this gonadotropin. The pool of follicles at the beginning of the oestrous cycle is about 30-40, most of which are small (< 3 mm) and growing. Then, the pool of follicles increases to about 80 in the mid-luteal phase but about 50 of them are small and 30 are medium sized (3-6.9 mm). Some of these follicles are in the growing phase, but some are atretic. Between days 7 and 15 of the oestrous cycle the percentage of atretic follicles fluctuates between 12 and 73%. At that time there are no large (> 7 mm) follicles because of the suppressing effect of progesterone. The number of small follicles declines after luteolysis. From the pool of medium follicles, large follicles are selected under the influence of LH, but about 70% of the medium-sized follicles become atretic. Because of the long-lasting selection process there is a significant heterogeneity in the diameter of large follicles in oestrus. However, the number of follicles correlates with the number of corpora lutea after ovulation. Individual follicular development and the relationship between follicles are still poorly known. The use of ultrasonography may give a closer insight into these phenomena. 相似文献
90.
Kuzmak J Rola M Gallay K Chebloune Y 《Comparative immunology, microbiology and infectious diseases》2007,30(4):211-223
Caprine arthritis-encephalitis virus (CAEV) infection in goats is worldwide but with higher prevalence in industrialized countries. While positive serology of CAEV in Polish goats was reported there was no genetic study of this virus. In this study, we described the molecular characterization of lentiviruses isolated from seropositive goats from Poland. We cloned and sequenced a fragment from the gag gene covering part of the coding sequences for the matrix (MA) p17 and for the capsid (CA) p25 proteins. Resulting nucleotide sequences were aligned with those from other ovine/caprine lentivirus isolates. We present data showing that the sequences of most goat lentivirus isolates are closer to the prototypic CAEV-Co isolate, nevertheless from one goat we isolated a virus that is closer to the sheep Maedi Visna virus (MVV) isolate. This might indicate a recent cross-species infection from sheep to goat. 相似文献