全文获取类型
收费全文 | 209篇 |
免费 | 9篇 |
专业分类
林业 | 10篇 |
农学 | 4篇 |
基础科学 | 1篇 |
68篇 | |
综合类 | 16篇 |
农作物 | 10篇 |
水产渔业 | 6篇 |
畜牧兽医 | 89篇 |
园艺 | 2篇 |
植物保护 | 12篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 7篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 10篇 |
2016年 | 6篇 |
2015年 | 5篇 |
2014年 | 7篇 |
2013年 | 13篇 |
2012年 | 12篇 |
2011年 | 20篇 |
2010年 | 11篇 |
2009年 | 7篇 |
2008年 | 20篇 |
2007年 | 20篇 |
2006年 | 19篇 |
2005年 | 9篇 |
2004年 | 5篇 |
2003年 | 11篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1989年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有218条查询结果,搜索用时 968 毫秒
41.
42.
Maria Orfanoudaki Anja Hartmann Julia Mayr Flix L. Figueroa Julia Vega John West Ricardo Bermejo Christine Maggs Markus Ganzera 《Marine drugs》2021,19(6)
This study presents the validation of a high-performance liquid chromatography diode array detector (HPLC-DAD) method for the determination of different mycosporine-like amino acids (MAAs) in the red alga Bostrychia scorpioides. The investigated MAAs, named bostrychines, have only been found in this specific species so far. The developed HPLC-DAD method was successfully applied for the quantification of the major MAAs in Bostrychia scorpioides extracts, collected from four different countries in Europe showing only minor differences between the investigated samples. In the past, several Bostrychia spp. have been reported to include cryptic species, and in some cases such as B. calliptera, B. simpliciuscula, and B. moritziana, the polyphyly was supported by differences in their MAA composition. The uniformity in the MAA composition of the investigated B. scorpioides samples is in agreement with the reported monophyly of this Bostrychia sp. 相似文献
43.
Anja Nüsse Deborah Linsler Ralf Loges Thorsten Reinsch Friedhelm Taube 《Archives of Agronomy and Soil Science》2013,59(14):1925-1931
ABSTRACTManagement of grassland may affect the dynamics of soil organic carbon (SOC). Objectives were to analyze the effect of different harvesting frequencies and nitrogen fertilization regimes on SOC and total N stocks in a field trial on a sandy loam to loamy sand soil of a grassland site near Kiel (Germany). Additionally, effects on microbial biomass C (Cmic) and ergosterol (as proxy for fungi) contents, water-stable aggregate size-classes and density fractions were studied. In the surface soil (0–10 cm), SOC and total N stocks, amounts of large water-stable macroaggregates (> 2000 µm) and contents of Cmic and ergosterol were significantly higher under a five cut regime. Cmic (rSpearman = 0.61) and ergosterol contents (rSpearman = 0.67) were correlated with amounts of large water-stable macroaggregates suggesting that fungi and microbial biomass play an important role in binding of small macroaggregates into large macroaggregates. The free light fraction of SOM showed significantly higher C concentrations under three cut compared to five cut at 30–60 cm, presumably related to the C/N ratio and the decomposability of root litter. This study indicates the importance of cutting frequency on SOC and total N stocks, amounts of large macroaggregates and contents of Cmic and ergosterol. 相似文献
44.
Kaiping Deng Steffen Uhlig Laura B. Goodman Hon S. Ip Mary Lea Killian Sarah M. Nemser Jodie Ulaszek Shannon Kiener Matthew Kmet Kirstin Frost Karina Hettwer Bertrand Colson Kapil Nichani Anja Schlierf Andriy Tkachenko Mothomang Mlalazi-Oyinloye Andrew Scott Ravinder Reddy Gregory H. Tyson 《Journal of veterinary diagnostic investigation》2022,34(5):825
The COVID-19 pandemic presents a continued public health challenge. Veterinary diagnostic laboratories in the United States use RT-rtPCR for animal testing, and many laboratories are certified for testing human samples; hence, ensuring that laboratories have sensitive and specific SARS-CoV2 testing methods is a critical component of the pandemic response. In 2020, the FDA Veterinary Laboratory Investigation and Response Network (Vet-LIRN) led an interlaboratory comparison (ILC1) to help laboratories evaluate their existing RT-rtPCR methods for detecting SARS-CoV2. All participating laboratories were able to detect the viral RNA spiked in buffer and PrimeStore molecular transport medium (MTM). With ILC2, Vet-LIRN extended ILC1 by evaluating analytical sensitivity and specificity of the methods used by participating laboratories to detect 3 SARS-CoV2 variants (B.1; B.1.1.7 [Alpha]; B.1.351 [Beta]) at various copy levels. We analyzed 57 sets of results from 45 laboratories qualitatively and quantitatively according to the principles of ISO 16140-2:2016. More than 95% of analysts detected the SARS-CoV2 RNA in MTM at ≥500 copies for all 3 variants. In addition, for nucleocapsid markers N1 and N2, 81% and 92% of the analysts detected ≤20 copies in the assays, respectively. The analytical specificity of the evaluated methods was >99%. Participating laboratories were able to assess their current method performance, identify possible limitations, and recognize method strengths as part of a continuous learning environment to support the critical need for the reliable diagnosis of COVID-19 in potentially infected animals and humans. 相似文献
45.
Zorana Milanovi Jelena Veki Vladimir Radonji Anja Ili Boovi Aleksandra Zeljkovi Jelena Janac Vesna Spasojevi‐Kalimanovska Jesse Buch Ramaswamy Chandrashekar
anka Boji‐Trbojevi Ljiljana Hajdukovi Mary M. Christopher Milica Kova
evi Filipovi 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2019,33(4):1686-1694
46.
47.
Visible browning is a typical feature of callus cultures derived from shoot tips of mature Scots pine (Pinus sylvestris L.). Because the ability of callus to regenerate is low, we determined the effect of browning on growth and changes in cellular structure during culture. Striking alterations in cellular structure were detected by LM (light microscopy), EM (electron microscopy) and SEM (scanning electron microscopy). Accumulation of phenolic substances was shown by histochemical staining. Staining for beta-glucosidase activity of soluble proteins that had been subjected to polyacrylamide gel electrophoresis indicated lignification of cells. The measured growth rate of callus was low compared with a hypothetical growth curve. Peroxidase activity increased rapidly soon after the start of the culture period, but especially between the second and third weeks of culture. At this time, the degradation of cell membranes and browning began coincident with the loss of chlorophyll. We conclude that browning is associated with cell disorganization and eventual cell death, making tissue culture of mature pine especially difficult. 相似文献
48.
We studied the location and distribution of a bacterial isolate, a Mycobacterium sp., in buds of Scots pine (Pinus sylvestris L.). Using a probe specific for the 16S rRNA of the Mycobacterium sp., the bacterium was found by in situ hybridization in the meristematic tissues of 40% of all bud samples examined. Because we had previously found other bacterial and fungal endophytes in the meristematic tissues of Scots pine buds, we studied their occurrence in buds during shoot development and dormancy. Using probes targeted to the 16S or 18S rRNA of the endophytes Mycobacterium sp., Methylobacterium spp., Pseudomonas spp. and Rhodotorula minuta, endophytes were found in association with growing tissues, with Methylobacterium spp. being the dominant species. Endophytes were detected in abundance before elongation or differentiation of a bud, but once a tissue was fully developed, endophytes were no longer detected. Metabolic activity of the endophytes was suppressed at the onset of, and during, dormancy of Scots pine, but recovered before the following growing season. 相似文献
49.
50.
Anja Guckland Bernd Ahrends Uwe Paar Inge Dammann Jan Evers Karl Josef Meiwes Egbert Sch?nfelder Thomas Ullrich Michael Mindrup Nils K?nig Johannes Eichhorn 《European Journal of Forest Research》2012,131(6):1869-1887
Forest liming is a common measure to counteract soil acidification. In forest practice, lime is applied to the forest floor where it changes the chemical properties. However, little is known about the depth impact of liming and the depth translocation of lime components. To investigate the long-term impact of forest liming, several study plots have been established in the 1980s in Germany in stands with different site conditions. We analysed soil chemical data obtained during the last 28?years from 45 of the study plots. We examined the depth impact of liming and predicted the main factors responsible for the increase in Calcium (Ca) and Magnesium (Mg) stocks after liming in the mineral soil using multiple linear regression analyses (MLR). Stocks of Ca and Mg as well as base saturation (BS) showed a strong depth gradient with significant differences between limed and control plots down to 40?cm of the mineral soil. About 65–70?% of applied Ca and Mg were recovered in the forest floor and the upper 40?cm of the mineral soil. BS in 0–40?cm increased by a mean of 11?%. MLR models could explain 48–74?% of the variation in mean changes of Ca and Mg in 0–10, 10–20 and 20–40?cm soil depth when soil and climate variables, amount of applied lime and years after liming are included in the model. After testing the model robustness with a cross-validating procedure, we concluded that these models might be applied to many regions in Central Europe with comparable soil and climate conditions and thus, have widespread application. 相似文献