全文获取类型
收费全文 | 67篇 |
免费 | 7篇 |
专业分类
林业 | 2篇 |
10篇 | |
综合类 | 20篇 |
农作物 | 1篇 |
水产渔业 | 4篇 |
畜牧兽医 | 36篇 |
植物保护 | 1篇 |
出版年
2021年 | 1篇 |
2018年 | 2篇 |
2013年 | 3篇 |
2012年 | 1篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2008年 | 3篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 2篇 |
2001年 | 1篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 3篇 |
1983年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 2篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1943年 | 1篇 |
1942年 | 1篇 |
1938年 | 1篇 |
1865年 | 1篇 |
排序方式: 共有74条查询结果,搜索用时 46 毫秒
1.
In a large pig breeding herd with high prevalence of post-parturient diseases of the sows, weaned sows of different parity groups with (n = 663) or without (n = 1125) recidiving mastitis metritis agalactia (MMA) in their previous history were subjected to ultrasonography. A total of 114 of 663 sows with recidiving MMA in their previous history and with ultrasonographic visible mammary gland changes, and 157 of sows without recidiving MMA in their previous history were culled and subjected to gross pathological and bacteriological examination of their mammary glands. The sows having suffered MMA had more (p < 0.001) hyperechogenic images in their mammary glands compared with the sow having suffered no recidiving MMA. Abdominal glands were more (p < 0.01) prone to pathological changes compared with the pectoral ones. Sows of high parity had more hyperechogenic images and gross pathological changes in their mammary glands compared with the sows of low parity. 相似文献
2.
Elizabeth M. Bach Sara G. Baer Clinton K. Meyer Johan Six 《Soil biology & biochemistry》2010,42(12):2182-2191
Many biotic and abiotic factors influence recovery of soil communities following prolonged disturbance. We investigated the role of soil texture in the recovery of soil microbial community structure and changes in microbial stress, as indexed by phospholipid fatty acid (PLFA) profiles, using two chronosequences of grasslands restored from 0 to 19 years on silty clay loam and loamy fine sand soils in Nebraska, USA. All restorations were formerly cultivated fields seeded to native warm-season grasses through the USDA’s Conservation Reserve Program. Increases in many PLFA concentrations occurred across the silty clay loam chronosequence including total PLFA biomass, richness, fungi, arbuscular mycorrhizal fungi, Gram-positive bacteria, Gram-negative bacteria, and actinomycetes. Ratios of saturated:monounsaturated and iso:anteiso PLFAs decreased across the silty clay loam chronosequence indicating reduction in nutrient stress of the microbial community as grassland established. Multivariate analysis of entire PLFA profiles across the silty clay loam chronosequence showed recovery of microbial community structure on the trajectory toward native prairie. Conversely, no microbial groups exhibited a directional change across the loamy fine sand chronosequence. Changes in soil structure were also only observed across the silty clay loam chronosequence. Aggregate mean weighted diameter (MWD) exhibited an exponential rise to maximum resulting from an exponential rise to maximum in the proportion of large macroaggregates (>2000 μm) and exponential decay in microaggregates (<250 μm and >53 μm) and the silt and clay fraction (<53 μm). Across both chronosequences, MWD was highly correlated with total PLFA biomass and the biomass of many microbial groups. Strong correlations between many PLFA groups and the MWD of aggregates underscore the interdependence between the recovery of soil microbial communities and soil structure that may explain more variation than time for some soils (i.e., loamy fine sand). This study demonstrates that soil microbial responses to grassland restoration are modulated by soil texture with implications for estimating the true capacity of restoration efforts to rehabilitate ecosystem functions. 相似文献
3.
M. v. Cotta M. v. Cotta Mördes v. Pannewib Robert Rühn Paur v. Stelzl v. Deltheim Schulze Q. v. Mikleben Lreiherr v. Lflanteuffel Lreiherr v. Berg Qeitel M. Lreiherr v. Berg v. Michael H. C. Bär Baer A. Chieriod Berger Rettftadt Gekner Wlrici Lreiherr v. Schmerzing Sprenger Pommrich v. Strune Matufchka v. E. Q. Brunft Rnaudt Mördlinger Rnipping v. Mangenheim C. A. Baum L. Mehlborn G. v. Stieglik H. v. Biegefar C. Grebe v.n Baumbach Braun R. Blohmer 《European Journal of Forest Research》1865,9(1):322-324
Ohne Zusammenfassung
f. f?chf. Dberforftmeifter.
f. bahr. Regierungs- und Forftrath von Mürzburg.
f. preuk. Dberforftmeifter aus Breslau.
f. f?chf. Dberforftmeifter.
f. bahr. Regierungs- und Forftrath von Augsburg.
f. bahr. Regierungs- und Forftrath aus Regensburg.
Dberj?germeifter von Braunfchweig.
f. bahr. Regierungs- und Forftrath aus München.
f. f?chf. Dberf?rfter.
f. f?chf. Dberforftmeifter.
f. f?chf. Dberforftrath.
herz. braunfchweig. Forftmeifter von Blanfenburg.
Direftor der fürftlich Cfterhazh’fchen Herrfchaft Spoly Parsto.
fürftl. fondershauf. Dberfortmeifter.
f. bahr. Redierf?rfter don Schmarzenbach.
f. preuk. Dberf?rfter.
f. f. Forftrath aus Brekburg.
f. preuk. Dberf?rfter von Altruppin.
f. hann?v. Forftmeifter von Rienburg.
Forftmeifter in preuk. Schleften.
f. preuk. Dberforftmeifter von Berlin.
herz. aftenburg. Dberfortmeifter.
f. preuk. Dberf?rfter.
f. f?chf. Dberf?rfter.
f. ruff. Forftfomiff?r aus Marfchau.
f. preuk. Forftinfpeftor.
f. f?chf. Forftinfpeftor.
grokh. meimar. Forftinfpeftor von Martfuhl.
f. mürttb. Dberf?rfter und Brofeffor aus Hohenheim.
f. hannov. Forftmeifter aus Hammeln.
Dberforftmeifter aus Sotha.
herz. altenburg. Dberf?rfter aus Hummelshain.
herz. altenburg. Revierf?rfter aus Milchwig.
herz. altenburg. geheimer Finanzrath und Dberforftmeifter.
herz. altenb. Dberforftmeifter aus Hummelshain.
grokh. f?chf. geheimer Dberforftrath aus Qifenach.
herz. naffau. Dberforftrath aus Miesbaden.
grokh. heff. Dberforftfefret?r aus Darmftadt.
f. f?chf. Dberforftmeifter. 相似文献
4.
The growth data of a commercial aquaculture recirculation system were analysed to investigate the growth performance of reared
turbot (Psetta maxima). Three common growth models (von Bertalanffy, Gompertz and Schnute) were fitted to the growth data documented over a time
period of 6 years. To determine the most suitable model, three different criteria were used: (1) the Akaike index criterion,
(2) the sum of squared residuals and (3) the average daily deviation between the estimated final weight and the observed final
weight. The evaluation of the growth models showed that the Schnute model had the lowest Akaike index, the lowest sum of squared
residuals and the lowest daily deviation between estimated and real weight of all tested growth models. The Schnute model
produced sigmoid growth curves. The estimated growth coefficients were the most realistic ones in regard to biological interpretation.
In contrast, the von Bertalanffy growth model and the Gompertz model estimated inaccurate exponential growth curves and are
therefore unable to simulate the growth data as well as the Schnute model. The results indicate that the von Bertalanffy growth
model is not the optimal model to simulate the present growth data and that the growth potential of reared turbot has probably
not yet been fully exploited in the aquaculture system(s) examined (so far). 相似文献
5.
An acute respiratory disease, due to Diplococcus pneumoniae type 3, affecting Wistar and Sprague-Dawley rats is described. The infection was experimentally transmitted to Sprague-Dawley rats. The zoonotic potential of the condition dictated euthanasia of affected animals and instigation of rigid sanitary measures. 相似文献
6.
Hippocampi of 8 cattle, 12 sheep and 17 goats of both sexes and of different ages were studied light and electronmicroscopically. 相似文献
7.
8.
9.
Epidemic strain of Venezuelan equine encephalomyelitis virus from a vampire bat captured in Oaxaca, Mexico, 1970 总被引:1,自引:0,他引:1
A vampire bat, Desmodus rotundus, captured in Oaxaca, Mexico, in August 1970, was found to be infected with the epidemic strain of Venezuelan equine encephalomyelitis virus at the same time that an equine epizootic was occurring there. 相似文献
10.
Richard A. Baer Jr. 《Agriculture and Human Values》1989,6(3):99-104
Michael Eldridge's critique of the author's earlier paper on the place of theology in agricultural ethics at state universities fails in at least three places: (1) Eldridge presents an inadequate picture of how basic assumptions function in human thinking and misuses terms like public, private, particular, empirical, and common experience; (2) he wrongly distinguishes between philosophers and theologians on the bais of their openness to new data, ideas, and public criticism; (3) he misunderstands the meaning of the First Amendment. Baer argues that whenever faculty at a state university deal with the Big Questions—who we are, how we should live, and what it all means—they must be seen, for First Amendment purposes, as operating within the realm of religion. Without such a functional definition of religion, the state will inevitably give unfair advantage to nontheistic, secular answers to the Big Questions. Eldridge is wrong to claim that Dewey escapes the liabilities of particularity and parochialism in a way that theologians do not. He also misunderstands the nature of the First Amendment when he argues that public schools may legitimately propagate Dewey's naturalistic variety of religion. Baer claims that when state universities address the Big Questions, the demands of public justice will be met only if theologians participate in the discussion and debate.Richard A. Baer, Jr. is professor of environmental ethics at Cornell University and a Fellow of the Center for Public Justice in Washington, D.C. 相似文献