全文获取类型
收费全文 | 143篇 |
免费 | 11篇 |
专业分类
林业 | 1篇 |
农学 | 5篇 |
基础科学 | 1篇 |
20篇 | |
综合类 | 38篇 |
水产渔业 | 5篇 |
畜牧兽医 | 67篇 |
园艺 | 4篇 |
植物保护 | 13篇 |
出版年
2023年 | 1篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 2篇 |
2014年 | 10篇 |
2013年 | 8篇 |
2012年 | 6篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 5篇 |
2008年 | 9篇 |
2007年 | 8篇 |
2006年 | 8篇 |
2005年 | 10篇 |
2004年 | 7篇 |
2003年 | 4篇 |
2002年 | 5篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1966年 | 2篇 |
1964年 | 1篇 |
1943年 | 1篇 |
1935年 | 2篇 |
1911年 | 1篇 |
1909年 | 3篇 |
1908年 | 4篇 |
1907年 | 1篇 |
1901年 | 1篇 |
排序方式: 共有154条查询结果,搜索用时 31 毫秒
61.
Calcium concentration and cold hardiness in woody shoots of young ‘Delicious’ apple trees increased during the first half of the dormant season by early-fall whole-tree application of bioregulators and/or plant protectant. Compared with untreated controls, the plant protectant, α-[(1,3-dioxolan-2-ylmethoxy) imino] benzene acetonitcile [Hytech Polymer, (formerly ProTecTM), Agro-K, Corp., Minneapolis, MN, USA] applied in September at 5 or 10% induced more cold hardiness in late October and November, whereas treating at 0.05% with the bioregulator, 2-chloroethyl-methyl-bis(phenylmethoxy)silane [CGA-15281, Novartis International AG, (formerly Ciba-Geigy Limited) Basel, Switzerland], induced greater cold hardiness and higher woody tissue calcium concentration in November and December. Applied in October, CGA-15281 resulted in woody tissue with the highest cold hardiness rating from November through March. From October 28 through 8 December, tissue from control trees had the lowest calcium concentration and frequently the least amount of cold hardiness. In woody stems of young apple trees, cold hardiness was more closely related to calcium concentration than that of the other eleven measured mineral elements; this was especially apparent from November to March (r = ?0.856). 相似文献
62.
63.
Curry A 《Science (New York, N.Y.)》2006,314(5805):1533-1535
64.
Background
Systemic hypertension is a prominent feature in humans with metabolic syndrome (MS) and this is partly caused by an enhanced endothelin-1 (ET-1) mediated vasoconstriction. There are indications that systemic hypertension might be a feature in equine metabolic syndrome (EMS) but if ET-1 is involved in the development of hypertension in horses is not known. Increased levels of cortisol have also been found in humans with MS but there are no reports of this in horses. Before blood pressure, plasma ET-1 and serum cortisol can be evaluated in horses with EMS, it is necessary to investigate the interday variation of these parameters on clinically healthy horses. The aims of the present study were therefore to evaluate the interday variation and influence of transportation on systemic blood pressure, plasma ET-1 and serum cortisol in healthy Standardbred and Icelandic horses, and to detect potential breed differences.Methods
Nine horses of each breed were included in the study. Blood pressure was measured and blood samples were collected between 6 and 9 am on two separate days. Eight of the horses (four of each breed) were transported to a new stable were they stayed overnight. The next morning, the sampling procedure was repeated.Results
The interday variation was higher for plasma ET-1 (37%) than for indirect pressure measurements (8-21%) and serum cortisol (18%). There were no differences in systemic blood pressure between the two breeds. The Icelandic horses had significantly lower serum cortisol and significantly higher plasma ET-1 concentrations compared to the Standardbred horses. Plasma ET-1 was significantly elevated after transportation, but systemic blood pressure and serum cortisol did not differ from the values obtained in the home environment.Conclusions
Indirect blood pressure, plasma ET-1 and serum cortisol are of interest as markers for cardiovascular dysfunction in horses with EMS. The elevated plasma ET-1 concentrations recorded after transportation was likely caused by a stress response. This needs to be considered when evaluating plasma ET-1 in horses after transportation. The differences detected in plasma ET-1 and serum cortisol between the two breeds might be related to differences in genetic setup, training status as well as management conditions. 相似文献65.
This paper examines the broad range of informal land transactions and arrangements migrants are entering into with customary landowners to gain access to customary land for export cash cropping in the oil palm belt of West New Britain, Papua New Guinea. Whilst these arrangements can provide migrants with relatively secure access to land, there are instances of migrants losing their land rights. Typically, the land tenure arrangements of migrants with more secure access to land are within a framework of property rights for social inclusion whereby customary landowners’ inalienable rights to land are preserved and the ‘outsider’ becomes an ‘insider’ with ongoing use rights to the land. Through socially embedding land transactions in place‐based practices of non‐market exchange, identities of difference are eroded as migrants assume identities as part of their host groups. This adaptability of customary land tenure and its capacity to accommodate large migration in‐flows and expanding commodity production undermines the argument common amongst proponents of land reform that customary tenure is static and inflexible. Before such claims are heeded, there must be more detailed empirical investigations of the diverse range of land tenure regimes operating in areas of the country experiencing high rates of immigration. 相似文献
66.
AJ Michael C Alexopoulos EA Pontiki DJ Hadjipavlou‐Litina P Saratsis HN Ververidis CM Boscos 《Reproduction in domestic animals》2010,45(2):201-207
The objective of this study was to evaluate the quality of chilled dog semen processed with extenders containing various concentrations of N‐acetyl‐L‐cysteine (NAC). Ejaculates from five dogs were collected, pooled and evaluated for concentration, motility, rapid steady forward movement (RSF‐movement), viability, acrosomal integrity and by the hypo‐osmotic swelling test (HOST). In addition, superoxide anion (O2‐?) production, hydroxyl radicals (OH?) and total reactive oxygen species (tROS) were determined. The pool was divided into five aliquots, which were diluted to a final concentration of 66.66 × 106 spermatozoa/ml with Tris‐glucose‐egg yolk extender containing one of the following concentrations of NAC (0, 0.5, 1, 2.5 or 5 mm ). The semen aliquots were chilled and preserved at 4°C. Semen quality was evaluated after rewarming at 72 h. Sperm motility was significantly higher with the 0.5 mm concentration compared with the control group (p = 0.001). Rapid steady forward movement was higher with the 0.5 and 1 mm concentrations compared with the control and 5 mm group (p < 0.001). Viability and HOST percentages were not significantly altered. Compared with the control, the 5 mm concentration showed significantly reduced percentages of spermatozoa with normal acrosomes (p = 0.049). None of the ROS values at 72 h were significantly affected by the presence of NAC in semen extenders, although all NAC concentrations showed lower O2‐? and OH? values compared with the control. Only the concentrations of 1 and 5 mm inhibited the significant increase of tROS values after 72 h, compared with the fresh semen value. In conclusion, NAC supplementation of semen extenders is beneficial to semen motility of canine spermatozoa during chilling with the 0.5 mm concentration being the most effective, although no significant ROS inhibition was observed at 72 h. 相似文献
67.
C.F. Summers P.J. Warner R.G.W. Nairn M.G. Curry J. Flynn 《Biological conservation》1980,17(2):115-123
Common seals Phoca vitulina vitulina Linnaeus 1758 were surveyed throughout Ireland during the 1978 breeding season. Compared with the abundance of the species in Great Britain, the Irish stock is small. The results are discussed in relation to the activities of man, particularly bounty hunting to protect fisheries, and the availability of suitable breeding localities. Problems relating to stock management, not least of which is that the species is subject to legislation in the south but not in the north, are discussed. 相似文献
68.
Shelby Marie Curry Diego Mario David Labadan Navarro Ferdinando Nielsen Almeida Juliana Abranches Soares Almeida Hans Henrik Stein 《畜牧与生物技术杂志(英文版)》2014,(4):414-420
The objective of this experiment was to determine the standardized ileal digestibility(SID) of amino acids(AA) in 3sources of distillers dried grains with solubles(DDGS) with different concentrations of fat.Twelve growing barrows(initial body weight:76.1 ± 6.2 kg) were randomly allotted to a replicated 6×4 Youden square design with 6 diets and 4 periods.The fat content of the 3 sources of DDGS were 11.5,7.5,and 6.9%respectively.Diets contained 60%DDGS and fat concentration of the diets were 7.5,52,and 5.2%,respectively.Two additional diets containing the 2sources of DDGS with 75 and 6.9%fat were also formulated,and corn oil was added to these diets to increase the concentration of fat in the diets to levels that were calculated to be similar to the diet containing conventional DDGS with 11.5%fat.A N-free diet was also formulated to calculate endogenous losses of crude protein(CP) and AA from the pigs.Pigs were fed experimental diets during four 7-d periods.The first 5 d of each period were an adaptation period and ileal digesta were collected on d 6 and 7 of each period.The apparent ileal digestibililty(AID) and SID of CP and all indispensable AA,except AID Pro and SID of Trp,were greater(P 〈 0.01) in conventional DDGS than in the 2 sources of DDGS with reduced fat.Adding oil to the diets containing the 2 sources of DDGS with reduced fat did not consistently increase SID of AA.In conclusion,conventional DDGS has greater SID values for most AA compared with DDGS that contains less fat and inclusion of additional oil to diets containing low-fat DDGS does not increase AID or SID of AA.The lower AA digestibility in low-fat DDGS could not be overcome by the inclusion of additional fat to the diets. 相似文献
69.
Global metabolic profiling of 'Granny Smith' apple peel was employed for evaluating metabolomic alterations resulting from prestorage UV-white light irradiation. Apples were bagged midseason to restrict sunlight, harvested at the preclimacteric stage prior to bag removal, treated with fluorescent UV-white light for 0-48.5 h, and stored for 6 months at 0 degrees C. Trimethylsilyl (oxime) derivatized or underivatized aliquots of methanolic extracts from peel samples collected immediately after irradiation or following cold storage were evaluated using GC-MS and LC-UV/vis-MS, respectively. The profile, including more than 200 components, 78 of which were identified, revealed changes in the metabolome provoked by UV-white light irradiation and cold storage. Analyses of individual components selected using principal component analysis (PCA) models showed distinct temporal changes, before and after cold storage, related to prestorage irradiation in a diverse set of primary and secondary metabolic pathways. The results demonstrate metabolic pathways associated with ethylene synthesis, acid metabolism, flavonoid pigment synthesis, and fruit texture, are altered by prestorage irradiation, and many of the alterations are detectable after 6 months of cold storage in air. 相似文献
70.