全文获取类型
收费全文 | 61篇 |
免费 | 4篇 |
专业分类
林业 | 5篇 |
农学 | 1篇 |
33篇 | |
综合类 | 6篇 |
农作物 | 11篇 |
水产渔业 | 4篇 |
畜牧兽医 | 3篇 |
植物保护 | 2篇 |
出版年
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 2篇 |
2011年 | 4篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 4篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 5篇 |
2004年 | 1篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2000年 | 3篇 |
1998年 | 1篇 |
1995年 | 2篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1980年 | 1篇 |
1974年 | 1篇 |
1952年 | 1篇 |
1941年 | 1篇 |
排序方式: 共有65条查询结果,搜索用时 156 毫秒
61.
Büntgen U Frank DC Kaczka RJ Verstege A Zwijacz-Kozica T Esper J 《Tree physiology》2007,27(5):689-702
We analyzed growth responses to climate of 24 tree-ring width and four maximum latewood density chronologies from the greater Tatra region in Poland and Slovakia. This network comprises 1183 ring-width and 153 density measurement series from four conifer species (Picea abies (L.) Karst., Larix decidua Mill., Abies alba (L.) Karst., and Pinus mugo (L.)) between 800 and 1550 m a.s.l. Individual spline detrending was used to retain annual to multi-decadal scale climate information in the data. Twentieth century temperature and precipitation data from 16 grid-boxes covering the 48-50 degrees N and 19-21 degrees E region were used for comparison. The network was analyzed to assess growth responses to climate as a function of species, elevation, parameter, frequency and site ecology. Twenty ring-width chronologies significantly correlated (P<0.05) with June-July temperatures, whereas the latewood density chronologies were correlated with the April-September temperatures. Climatic effects of the previous-year summer generally did not significantly influence ring formation, whereas site elevation and frequency of growth variations (i.e., inter-annual and decadal) were significant variables in explaining growth response to climate. Response to precipitation increased with decreasing elevation. Correlations between summer temperatures and annual growth rates were lower for Larix decidua than for Picea abies. Principal component analysis identified five dominant eigenvectors that express somewhat contrasting climatic signals. The first principal component contained highest loadings from 11 Picea abies ring-width chronologies and one Pinus mugo ring-width chronology and explained 42% of the network's variance. The mean of these 12 high-elevation chronologies was significantly correlated at 0.62 with June-July temperatures, whereas the mean of three latewood density chronologies, which loaded most strongly on the fourth principal component, significantly correlated at 0.69 with April-September temperatures (P<0.001 over the 1901-2002 period in both cases). These groupings allow for a robust estimation of June-July (1661-2004) and April-September (1709-2004) temperatures, respectively. Comparison with reconstructions from the Alps and Central Europe supports the general rule of the dominant influence of growing season temperature on high-elevation forest growth. 相似文献
62.
The aim of this study was to determine the level of circulating immune complexes (CIC) in equine serum and the electrophoretic properties of the protein fraction thereof. The study was carried out using 42 clinically healthy breeding horses of noble half-blood. The average extinction value of CIC's in equine serum was E450 nm = 0.278 ± 0.09 nm. Generally, 23 protein fractions were identified in the molecular mass range between 294 and 25 kDa. Eight fractions whose molecular masses were 137, 72, 65, 52, 42, 32, 28, and 26 kDa, respectively, appeared in all analyzed samples. In 20 of the analyzed serum an additional nine protein fractions whose molecular masses were 260, 110, 84, 78, 67, 62, 57, 45, and 39 kDa, respectively, were identified. Circulating immune complexes are a source of information about immunologic processes that take place in mammals. Determining the average values of CIC levels and identifying the electrophoretic profile of proteins in clinically healthy horses could be useful in research and diagnostics. 相似文献
63.
Wanasundara PK Ross AR Amarowicz R Ambrose SJ Pegg RB Shand PJ 《Journal of agricultural and food chemistry》2002,50(24):6981-6988
Defibrinated bovine plasma (DBP) was treated with the microbial protease Flavourzyme to obtain protein hydrolysates with various degrees of hydrolysis (DH). The angiotensin I-converting enzyme (ACE) inhibiting activity of the hydrolyzed protein was assessed with hippuryl-His-Leu as the substrate. The amount of hippuric acid released, due to uninhibited ACE activity, was determined by high-performance liquid chromatography. ACE inhibiting (ACEI) activity was found to increase with increasing DH; the 43% DH hydrolysate exhibited the highest activity and had an IC(50) of 1.08 mg/mL. Peptide fractions with high ACEI activity were isolated using size exclusion chromatography. The fraction that possessed the highest ACEI activity contained peptides with GYP, HL(I), HPY, HPGH, L(I)F, SPY, and YPH sequence motifs, as determined by reversed-phase liquid chromatography-tandem mass spectrometry using a novel immonium precursor-ion scanning technique. Some of these motifs correspond to sequences found in bovine serum albumin, a potential source of ACEI peptides in bovine plasma. 相似文献
64.
Influence of temperature and Artemia enriched with ω‐3 PUFAs on the early ontogenesis of Atlantic sturgeon,Acipenser oxyrinchus Mitchill, 1815 下载免费PDF全文
Ryszard Kolman Oleksii Khudyi Olga Kushniryk Lidiia Khuda Maja Prusinska Grzegorz Wiszniewski 《Aquaculture Research》2018,49(5):1740-1751
Successful breeding of fish species in aquaculture depends on several factors, among which the temperature and feed are the most significant ones. This study was designed to evaluate the effect of temperature in the range of 14–18°C on the rate of embryogenesis and duration of larva period and to estimate the efficiency of Artemia nauplii enriched with PUFAs in growing sturgeon larvae. The temperature of 16°C is the most suitable for both egg incubation and Atlantic sturgeon prelarvae maintenance under aquaculture conditions. Even minor temperature fluctuations of 1 degree up or down leads to increased loss both of eggs and prelarvae. Increased temperature shortens the incubation period but has a lesser impact on the duration of prelarvae onset of external feeding. The technology of Artemia nauplii bioencapsulation with a PUFA‐containing supplement in A. oxyrinchus rearing increases sturgeon larvae weight by 1.5 times at a constant survival dynamic. 相似文献
65.
Katarzyna Kowalczewska-Madura Renata Dondajewska Ryszard Gołdyn Anna Kozak Beata Messyasz 《Water, air, and soil pollution》2018,229(8):280
The ribbon type Lake Durowskie (Western Poland) is currently undergoing a sustainable restoration process due to water quality deterioration, manifested in water blooms, low transparency, and oxygen deficits near the bottom sediments. Three restoration methods were applied: (i) hypolimnion aeration using two wind-driven pulverizing aerators installed at the deepest places, (ii) phosphorus inactivation using small doses of iron sulfate and magnesium chloride several times a year, and (iii) biomanipulation using pike fry stocking. Research on the exchange of phosphorus in the sediment-water interphase was conducted in the years 2009–2016 to determine the multiannual changes of internal phosphorus loading from bottom sediments during the restoration process. The sustainable approach resulted in a decrease of internal phosphorus loading and a gradual increase in the sorption capacity of bottom sediments, particularly noticeable in the last 2 years. The content of phosphorus in the sediment and in the interstitial water fluctuated, showing an increase during the first years of restoration and then a gradual decrease. It was proved that the process of sustainable restoration is cheap and does not interfere strongly with the ecosystem, although it is long-lasting. It should be continued for many years, especially in the case of continuous external loading of the lake with nutrients from the catchment area, i.e., until the water quality in the main tributary improves and the lake ecosystem stabilizes. 相似文献