首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   122篇
  免费   7篇
林业   1篇
农学   1篇
基础科学   2篇
  1篇
综合类   10篇
农作物   37篇
畜牧兽医   73篇
植物保护   4篇
  2021年   1篇
  2020年   1篇
  2019年   1篇
  2018年   1篇
  2017年   2篇
  2016年   4篇
  2015年   4篇
  2014年   4篇
  2013年   8篇
  2011年   2篇
  2010年   3篇
  2009年   3篇
  2008年   6篇
  2007年   4篇
  2006年   2篇
  2004年   1篇
  2002年   1篇
  2001年   1篇
  2000年   3篇
  1999年   2篇
  1998年   5篇
  1997年   5篇
  1996年   5篇
  1995年   3篇
  1993年   5篇
  1992年   3篇
  1991年   1篇
  1990年   5篇
  1989年   2篇
  1988年   3篇
  1978年   2篇
  1977年   2篇
  1976年   1篇
  1975年   1篇
  1974年   3篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
  1970年   2篇
  1969年   2篇
  1968年   1篇
  1967年   1篇
  1966年   1篇
  1965年   4篇
  1964年   3篇
  1963年   3篇
  1962年   2篇
  1961年   1篇
  1960年   2篇
  1958年   3篇
排序方式: 共有129条查询结果,搜索用时 15 毫秒
1.
2.
The aim of this study was to characterize the vocalizations produced during electroejaculation under general anaesthesia in pampas deer males and to determine whether the characteristics of those vocalizations differ in adult and young pampas deer males. Electroejaculation was applied to 13 adults (AM) and 13 young (YM) males under general anaesthesia. Vocalizations were digitally recorded, and the number and duration of vocalizations, the latency in relation to each voltage, the total time vocalizing, and the structure of the fundamental frequency (F0) [initial frequency (Fstart), maximal frequency (Fmax), minimal frequency (Fmin) and final frequency (Fend)] were analysed. No male vocalized with 0 V; the number of animals that vocalized increased at 2 and 3 V and increased again at 4, 5 and 6 V (p < 0.05). The latency time from the beginning of each series (each voltage) decreased until 4 V (p < 0.01). The number of vocalizations/voltage increased from 4 V (p < 0.05). The length of each vocalization and the total time during which animals vocalized were greater in YM than AM (p = 0.02 and p = 0.01, respectively). Similarly, the fundamental frequencies were higher in YM than AM (p ≤ 0.05). Overall, we concluded that the vocalizations emitted during electroejaculation in pampas deer under general anaesthesia are related to the voltage applied during the process. Young males vocalize more time, probably due to a greater sensibility to the electric stimulation. The differences in the characteristics of the vocalizations between adult and young males may be related to the anatomic differences in the neck of adult or young males.  相似文献   
3.
Malm  O  Guimarães  JRD  Castro  MB  Bastos  WR  Viana  JP  Branches  FJP  Silveira  EG  Pfeiffer  WC 《Water, air, and soil pollution》1997,97(1-2):45-51
Informal economy of gold mining has contaminated some important river basins in Amazon. Follow-up studies on critical compartments showed some areas with high Hg levels in fish as well as in human hair samples. Average Hg in piscivorous fish in the Madeira river itself was 846 ppb (N=284) with a maximum of 3921 ppb. Mercury in fish from non polluted areas in this basin shows high variability, even for single species. A seasonal variation in Hg content was observed, with higher values at the end of the dry season. In the upper Tapajós basin comparable values were found for fish but with a definite decreasing trend downstream. Average value for piscivorous fish in the whole Tapajós basin is 482 ppb (N=122) with a maximum value of 3770 ppb. Hair Hg was higher in fishing villages in the Tapajós (average: 17 ppm; with N=432 and maximum value of 176 ppm) than in the Madeira (average: 9 ppm; N=169; maximum 71 ppm), and data from some areas of the Tapajós suggest a decrease with time. Mercury was much higher in urine of goldshop workers in Santarém (low Tapajós) than in Alta Floresta (high Tapajbs) and show a decreasing trend in both cases, probably related to the significant decline in gold mining activities during the study period (1986–1994).  相似文献   
4.
Three groups of horses and ponies (N = 13, 13 and 12) were treated with ivermectin paste (0.2 mg/kg p.o.), avermectin B1 solution (0.2 mg/kg p.o.), or fenbendazole suspension (10 mg/kg via nasogastric tube). The avermectin B1 was a 1% solution in a propylene glycolglycerol formal base. Faecal strongyle egg counts were performed before, and 14, 28, 42, 56 and 70 d, after treatment. Full-thickness skin biopsies from the neck, pectoral and umbilical regions were examined for Onchocera microfilaria before treatment, and again 14 and 70 d later. Ivermectin therapy produced a significant (P less than 0.01) decrease in mean strongyle egg counts 14, 28, 42 and 56 d after treatment. Avermectin B1 therapy resulted in significant (P less than 0.01) decreases in mean strongyle egg counts 14, 28 and 42 d after treatment. All horses given ivermectin or avermectin B1 had zero strongyle egg counts 14 and 28 d after treatment. Fenbendazole failed to significantly decrease strongyle egg counts. Both ivermectin and avermectin B1 resulted in zero microfilaria counts in all horses 14 d after treatment. On day 70 the percentage decrease in microfilaria counts were 100% and 99.6% respectively. Fenbendazole failed to significantly decrease microfilaria counts. The oral administration of this formulation of avermectin B1 appeared to be highly efficacious against intestinal strongyles and Onchocera microfilaria. The duration of anti-strongyle activity was, however, significantly (P less than 0.01) shorter than that of ivermectin paste.  相似文献   
5.
Comparative Earth History and Late Permian Mass Extinction   总被引:6,自引:0,他引:6  
The repeated association during the late Neoproterozoic Era of large carbon-isotopic excursions, continental glaciation, and stratigraphically anomalous carbonate precipitation provides a framework for interpreting the reprise of these conditions on the Late Permian Earth. A paleoceanographic model that was developed to explain these stratigraphically linked phenomena suggests that the overturn of anoxic deep oceans during the Late Permian introduced high concentrations of carbon dioxide into surficial environments. The predicted physiological and climatic consequences for marine and terrestrial organisms are in good accord with the observed timing and selectivity of Late Permian mass extinction.  相似文献   
6.
Measurements of electrical conductivity at high pressure and temperature were taken on the lower mantle phase magnesiowustite with varying Fe3+ content. Although previous measurements at atmospheric pressure suggest Fe2+-Fe3+ hopping (small polaron) as the dominant conductivity mechanism, the present experiments show a change in charge transport mechanism with temperature. The lower temperature measurements are consistent with small polaron conduction, but at higher temperatures, which are more applicable to the lower mantle, a large polaron mechanism is suggested. Because these mechanisms have different temperature and compositional dependencies, this transition has important implications for extrapolation to mantle conditions.  相似文献   
7.
Resume Les qualités de ces fruits varient énormément d'une variété l'autre, les qualités d'une variété donnée étant fonction du sol, de la fumure, du climat, des traitements (tailles, application de pesticides) infligés aux arbres.La quantité et la nature des sucres (le saccharose prédomine chez pèches et abricots, mais non chez les prunes), la qualité et la nature des acides (acides malique, citrique, quinique, etc.) le pH (qui dépend du taux de neutralisation des acides, donc des éléments minéraux que l'arbre trouve dans le sol) définissent déjà les éléments essentiels du gout, plus ou moins acide, plus ou moins sucré. Le pH a beaucoup plus d'importance que le taux d'acides libres. Le taux d'acide ascorbique, très variable, parfois élevé, chez pêches, nectarines, cerises, est faible chez prunes, quetsches.L'étalement dans le temps des productions, obtenu en multipliant des variétés peu répandues, mais de grandes qualités (certaines pèches, beaucoup d'abricots, les nectarines) présente un intérèt certain à la fois pour le consommateur et le producteur.
Nutritional value of stone fruits
The quality of these kinds of fruit varies greatly, since the quality of a given variety depends on the soil, the fertilizer, the climate, and the treatment (pruning, application of pesticides) to which the trees have been exposed.The amount and nature of the sugar (saccharose predominates in peaches and apricots but not in plums), the quality and nature of the acids (malic, citric, quinic acids etc.), the pH (which depends on the degree of neutralization of the acids, hence the mineral elements the tree finds in the soil) determine already the basic elements of taste, i.e. more or less sour, more or less sweet. The pH is much more important than the amount of free acids. The amount of ascorbic acid which is very variable, sometimes high as in peaches, nectarines, cherries, is low in prunes and plums.It is of great interest to both the consumer and the producer to spread the production over a period of time, this has been made possible by multiplying little known varieties of high quality (certain peaches, many apricots, nectarines).

Zusammenfassung Die Qualität dieser Früchte variiert sehr stark von Sorte zu Sorte, da die Qualität einer bestimmten Sorte vom Boden, der Düngung, dem Klima und der Behandlung der Bäume (Baumschnitt, Behandlung mit Pestiziden) abhängt.Die Menge und Art des Zuckers (Saccharose überwiegt bei Pfirsichen und Aprikosen aber nicht bei Pflaumen), die Qualität und Art der Säuren (Apfel-, Zitronen- und Chinasäure), der ph-Wert (der vom Grad der Neutralisierung der Säuren, deren Mineralbestandteile der Baum im Bodem findet, abhängt) entscheiden bereits über die hauptsächlichtsten Geschmackselemente, d.h. mehr oder weniger sauer, mehr oder weniger süß. Das pH ist wesentlich wichtiger als der Gehalt an freien Säuren. Der Ascorbinsäuregehalt, der stark variiert und mitunter in Pfirsichen, Nektarinen und Kirschen hoch sein kann, ist dagegen in Pflaumen und Zwetschgen niedrig.Die zeitliche Ausdehnung der Erntesaison, die durch Vermehrung wenig verbreiteter aber hochqualitativer Sorten (gewisser Pfirsiche, vieler Aprikosen, der Nektarinen) erreicht wird, liegt sowohl im Interesse des Verbrauchers wie des Anbauers.


Exposé présenté le 3 mars 1971 au Colloque sar la qualité des fruits et légumes de l'O.C.D.E., Paris, à Saragosse, Espagne.  相似文献   
8.
A number of insecticides used for ectoparasite control in the livestock industry were screened for their efficacy against larvae of the screw-worm fly, Chrysomya bezziana, using in vivo and laboratory tests. Proprietary screw-worm fly treatments (after exposure to outdoor conditions for up to 10 days) were also tested against eggs and adults of C bezziana. Three of these were also evaluated on naturally acquired screw-worm infestations. Residual protection was generally of short duration. Among the organophosphorus compounds, the most effective formulations contained relatively high concentrations (3 to 4% al) of coumaphos, 2.5% fenchlorphos or low concentrations (0.05 to 0.5% al) of diazinon, chlorfenvinphos and fenthion methyl. Two chlorinated hydrocarbon insecticides containing 3% lindane and 5% dieldrin were very effective but are now prohibited for use in Australia. Preparations had serious deficiencies when used under field conditions, especially for treating large, deepseated myiases for which systemic insecticides are recommended. A comparison of methods demonstrated that a laboratory test could supersede live animal experimentation, at least for the initial screening of potential insecticides.  相似文献   
9.
10.
AIM: To develop and validate a simple and sensitive method using liquid chromatography-mass spectrometry (LC-MS) for quantification of articaine, and its major metabolite articainic acid, in plasma of red deer (Cervus elaphus), and to investigate the pharmacokinetics of articaine hydrochloride and articainic acid in red deer following S/C administration of articaine hydrochloride as a complete ring block around the antler pedicle.

METHODS: The LC-MS method was validated by determining linearity, sensitivity, recovery, carry-over and repeatability. Articaine hydrochloride (40?mg/mL) was administered S/C to six healthy male red deer, at a dose of 1?mL/cm of pedicle circumference, as a complete ring block around the base of each antler. Blood samples were collected at various times over the following 12 hours. Concentrations in plasma of articaine and articainic acid were quantified using the validated LC-MS method. Pharmacokinetic parameters of articaine and articainic acid were estimated using non-compartmental analysis.

RESULTS: Calibration curves were linear for both articaine and articainic acid. The limits of quantifications for articaine and articainic acid were 5 and 10?ng/mL, respectively. Extraction recoveries were >72% for articaine and >68% for articainic acid. After S/C administration as a ring block around the base of each antler, mean maximum concentrations in plasma (Cmax) of articaine were 1,013.9 (SD 510.1) ng/mL, detected at 0.17 (SD 0.00) hours, and the Cmax for articainic acid was 762.6 (SD 95.4) ng/mL at 0.50 (SD 0.00) hours. The elimination half-lives of articaine hydrochloride and articainic acid were 1.12 (SD 0.17) and 0.90 (SD 0.07) hours, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE: The LC-MS method used for the quantification of articaine and its metabolite articainic acid in the plasma of red deer was simple, accurate and sensitive. Articaine hydrochloride was rapidly absorbed, hydrolysed to its inactive metabolite articainic acid, and eliminated following S/C administration as a ring block in red deer. These favourable pharmacokinetic properties suggest that articaine hydrochloride should be tested for efficacy as a local anaesthetic in red deer for removal of velvet antlers. Further studies to evaluate the safety and residues of articaine hydrochloride and articainic acid are required before articaine can be recommended for use as a local anaesthetic for this purpose.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号