全文获取类型
收费全文 | 487篇 |
免费 | 20篇 |
国内免费 | 4篇 |
专业分类
林业 | 31篇 |
农学 | 20篇 |
基础科学 | 4篇 |
140篇 | |
综合类 | 69篇 |
农作物 | 28篇 |
水产渔业 | 17篇 |
畜牧兽医 | 110篇 |
园艺 | 31篇 |
植物保护 | 61篇 |
出版年
2023年 | 6篇 |
2022年 | 8篇 |
2021年 | 8篇 |
2020年 | 9篇 |
2019年 | 10篇 |
2018年 | 14篇 |
2017年 | 13篇 |
2016年 | 16篇 |
2015年 | 14篇 |
2014年 | 18篇 |
2013年 | 23篇 |
2012年 | 28篇 |
2011年 | 39篇 |
2010年 | 25篇 |
2009年 | 20篇 |
2008年 | 34篇 |
2007年 | 25篇 |
2006年 | 35篇 |
2005年 | 23篇 |
2004年 | 21篇 |
2003年 | 20篇 |
2002年 | 22篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 7篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 7篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1987年 | 3篇 |
1982年 | 3篇 |
1978年 | 3篇 |
1975年 | 2篇 |
1961年 | 1篇 |
1960年 | 1篇 |
1958年 | 3篇 |
1956年 | 1篇 |
1955年 | 1篇 |
1954年 | 1篇 |
1945年 | 1篇 |
1939年 | 3篇 |
1937年 | 1篇 |
1936年 | 1篇 |
1910年 | 2篇 |
1891年 | 1篇 |
1887年 | 1篇 |
排序方式: 共有511条查询结果,搜索用时 46 毫秒
81.
Dirk Jungmann Cornelia Bandow Thomas Gildemeister Roland Nagel Thomas G. Preuss Hans T. Ratte Cândida Shinn Lennart Weltje Hanna M. Maes 《Journal of Soils and Sediments》2009,9(2):94-102
Background, aim, and scope
Fenoxycarb is an insect growth regulator widely used to control a variety of pests. As a juvenile hormone analogue, it interacts with the natural hormones involved in insect development, inhibiting metamorphosis to the adult stage. Adverse effects of fenoxycarb on non-target organisms have been repeatedly observed and its rapid dissipation from water to the organic fraction of the sediment is known. The aim of this work was to investigate the impact of fenoxycarb on the development of sediment-dwelling larvae of the midge Chironomus riparius after exposure to spiked sediment. 相似文献82.
83.
In the summer of 2010 and during the following two seasons, a twig dieback of blueberries (Vaccinium corymbosum) was observed in southern Lower Saxony especially in younger plantations of the variety ‘Duke’. The sudden onset of a chlorosis and necrosis of individual twigs was associated with a destruction of the vascular cambium and with longitudinal streaks of brown discolourations in the xylem tissue deposited during the previous year. New shoots were often formed from the intact roots and from regions of older twigs located immediately above the soil surface. Potentially pathogenic fungi, including Godronia cassandrae, Phomopsis spp., Diplodia seriata, Pestalotiopsis sp., Paraconiothyrium sporulosum, Colletotrichum acutatum, Fusarium avenaceum and F. lateritium, were found sporadically on dead twigs, each fungus being present in 6 or fewer of the 12 plantations surveyed. Winter frost damage of xylem tissues was determined to be the main cause of the disease, facilitated by a delayed termination of vegetative growth which led to a lack of winter hardiness at the time-point of the first serious frost events. 相似文献
84.
Doolaege EH Raes K De Vos F Verhé R De Smet S 《Plant foods for human nutrition (Dordrecht, Netherlands)》2011,66(2):196-202
The absorption, distribution and elimination of carnosic acid, the main antioxidant found in rosemary was studied, in vivo, in rats. Therefore, carnosic acid was administrated in a single dose, intravenously (20.5 ± 4.2 mg/kg) and orally (64.3 ± 5.8 mg/kg),
to four and nine rats, respectively. Blood samples were collected at different time points, and plasma concentrations of carnosic
acid were determined using LC-MS. Furthermore, total collection of urine and feces was done during 4 h and 24 h for the intravenous
and oral administrations, respectively. After euthanizing the rats, intestinal content, liver and muscle tissue were sampled
to determine carnosic acid concentrations. The bioavailability of carnosic acid, after 360 min, was 40.1%. Traces of carnosic
acid were found in the rats intestinal content, liver and muscle tissue of abdomen and legs. The recovery of carnosic acid
in the feces, 24 h after oral administration, was 15.6 ± 8.2%. Carnosic acid is absorbed into the bloodstream after oral administration
in rats and is therefore bioavailable. It was found that carnosic acid in vivo is present in its free form and that its main elimination route is the fecal route. 相似文献
85.
86.
Andraud M Rose N Laurentie M Sanders P Le Roux A Cariolet R Chauvin C Jouy E 《Veterinary research》2011,42(1):44
Antimicrobial resistance is of primary importance regarding public and animal health issues. Persistence and spread of resistant strains within a population contribute to the maintenance of a reservoir and lead to treatment failure. An experimental trial was carried out to study the horizontal transmission of a fluoroquinolone-resistant Escherichia coli strain from inoculated to naïve pigs. All naïve contact pigs had positive counts of fluoroquinolone-resistant E. coli after only two days of contact. Moreover, re-infections of inoculated pigs caused by newly contaminated animals were suspected. A maximum likelihood method, based on a susceptible-infectious-susceptible (SIS) model, was used to determine the transmission parameters. Two transmission levels were identified depending on the quantity of bacteria shed by infected individuals: (i) low-shedders with bacterial counts of resistant E. coli in the faeces between 5*103 and 106 CFU/g (βL = 0.41 [0.27; 0.62]), (ii) high shedders with bacterial counts above 106 CFU/g (βH = 0.98 [0.59; 1.62]). Hence, transmission between animals could be pivotal in explaining the persistence of resistant bacteria within pig herds. 相似文献
87.
Closed‐chamber systems are commonly used to determine gaseous C and N emissions from agricultural soils. We investigated the effects of eight cuvette surfaces on two standard gas concentrations of NH3, N2O, CO2, and CH4 under laboratory conditions. Cuvette surface materials differentially affected gas adhesion or recovery as a function of the type and the concentration of the gases. Given the strong effects on results of gas measurements in closed‐chamber systems, both the type and the concentration of the measured gases need to be considered in selecting cuvette surface materials. 相似文献
88.
89.
Birzhan Usubaliev Agnese Kolondinska Brantestam Björn Salomon Larisa Garkava-Gustavson Roland von Bothmer 《Genetic Resources and Crop Evolution》2013,60(6):1843-1858
Barley (Hordeum vulgare L.) is one of the economically important cereal crops grown in the highlands of the Kyrgyz Republic. In marginal agricultural areas of the country barley is considered as irreplaceable and very suitable fodder crop for livestock. In this study the genetic diversity of currently grown farmers’ spring barley material from Naryn and Issik-Kul provinces is described. In order to capture maximum diversity present in farmer field’s different morphological types were collected. The 22 spring barley accessions collected in 2008 were described morphologically and analysed using fourteen simple sequences repeat (SSR) markers. Most material was two-rowed barley, 78 %, whereas six-rowed barley was only 22 %. The spike colours present were light yellow, dark yellow, brown and violet. The material varied also for such characters as length of spike and number of kernels per spike. For the SSR loci 129 alleles were detected with an average of 9.3 alleles per locus and a genetic diversity with an average of h = 0.721 per locus. Based on analysis of molecular variance the 71.3 % of genetic diversity accounted for within accession variation, whereas 27.4 % for among accession variation. The variation between provinces was not significantly different. A group of two-rowed barley was identified that was more closely related to six-rowed barley than to the rest of the two-rowed barley material. Two-rowed material currently grown in Kyrgyzstan is more diverse than six-rowed barley (h = 0.65, A = 8.8 vs. h = 0.59, A = 3.1). From this study we could conclude that the materials nowadays grown by farmers are mixtures. Since there are no geographic differentiation between these mixtures suggests that materials is frequently inter-exchanged between farmers and are most probably not landrace material. The question concerning the origin of these mixtures remains unsolved and further investigation will be carried out to identify sources of variation in farmers’ field. 相似文献
90.
Holthusen Hinrich H. F. Weber Roland W. S. 《European journal of plant pathology / European Foundation for Plant Pathology》2021,161(4):895-906
European Journal of Plant Pathology - In Northern Germany, a major share of postharvest losses of apple fruit is due to preharvest infections by pathogenic fungi. Little is known about their... 相似文献