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81.
DE MAIO D 《Science (New York, N.Y.)》1959,129(3364):1678-1679
Diisopropylfluorophosphate inhibited all the sulfhydryl proteases studied in our tests. This inhibition was most pronounced at pH 6.0. By first blocking the sulfhydryl group with p-chloromercuribenzoate, inhibition could be prevented. Neither cysteine nor choline gave appreciable reactivation of diisopropylfluorophosphate-inhibited bromelain. 相似文献
82.
Summary. Several new herbicides were tested for control of weeds in broadcast-seeded flooded tropical rice. Among the new herbicides, S-(2-methyl-l-piperidylcarbonyl-methyl)- O,O -di- n -propyl dithiophosphate (C-19490), S-(2-methyl-l-piperidylcarbonyl-methyl)- O,O -di- n -propyl dithiophosphate combined with 2-(1',2'-dimethylpropylamino)-4-ethylamino-6-methylmercapto- s -triazine [C-19490/C-18898 (C-288)], and N -secondary-butyl-4-tertiary-butyl-2,6-dinitroaniline (A-820) were highly selective in controlling Echinochloa crus-galli (barnyard grass) and other annual weeds under tropical conditions. S-(4-chlorobenzyl)- N,N -diethylthiol carbamate (benthiocarb) and N -(butoxymethyl)-2-chloro-2',6'-diethylacetanilide (butachlor) continued to look promising in our experiments. Only butachlor is widely used in Asia.
Désherbage chimique des cultures tropicales de riz inorndé, seméà la volée 相似文献
Désherbage chimique des cultures tropicales de riz inorndé, seméà la volée 相似文献
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Robyn S. HETEM Duncan MITCHELL Brenda A. DE WITT Linda G. FICK Shane K. MALONEY Leith C. R. MEYER Andrea FULLER 《Integrative zoology》2019,14(1):30-47
As one of the few felids that is predominantly diurnal, cheetahs (Acinonyx jubatus) can be exposed to high heat loads in their natural habitat. Little is known about long‐term patterns of body temperature and activity (including hunting) in cheetahs because long‐term concurrent measurements of body temperature and activity have never been reported for cheetahs, or, indeed, for any free‐living felid. We report here body temperature and locomotor activity measured with implanted data loggers over 7 months in 5 free‐living cheetahs in Namibia. Air temperature ranged from a maximum of 39 °C in summer to ?2 °C in winter. Cheetahs had higher (~0.4 °C) maximum 24‐h body temperatures, later acrophase (~1 h), with larger fluctuations in the range of the 24‐h body temperature rhythm (approximately 0.4 °C) during a hot‐dry period than during a cool‐dry period, but maintained homeothermy irrespective of the climatic conditions. As ambient temperatures increased, the cheetahs shifted from a diurnal to a crepuscular activity pattern, with reduced activity between 900 and 1500 hours and increased nocturnal activity. The timing of hunts followed the general pattern of activity; the cheetahs hunted when they were on the move. Cheetahs hunted if an opportunity presented itself; on occasion they hunted in the midday heat or in total darkness (new moon). Biologging revealed insights into cheetah biology that are not accessible by traditional observer‐based techniques. 相似文献
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Datura ferox seeds do not germinate when they are incubated intact and in darkness, even after 24 months of dry storage. If allowed to absorb water vapour for 3–4 weeks at 20°C, they lose dormancy, germinating even when incubated in darkness. The breakage of dormancy is directly related to the vapour pressure of the atmosphere where the seeds are stored, and good aeration is necessary for the process to occur. If seeds absorb liquid water, the toss of dormancy is much less than that of seeds stored in a saturated atmosphere. A similar effect is observed when seeds are buried in a soil at field capacity. The results indicate that a certain degree of imbibition, under good gas-exchange conditions, is important for breaking dormancy. As a hypothesis, it is proposed that most of the population remains dormant when not enough O2 is available for (he imbibed seed. The low rate of O2 entry could be due to poor diffusion through the water-saturated seed coat (seeds which absorb liquid water) or to a low O2 level in the surrounding atmosphere (soil at field capacity). One of the possible roles of O2 could be to oxidize the inhibitor(s) present in these seeds. La rupture de la dormance des semences de Datura ferox considérée comme un effet de l'absorplion de l'eau. Les semences de Datura ferox ne germent pas quand elles sont mises au germoir intactes et à l'obscurité, même aprés 24 mois de conservation au sec. Si elles peuvent absorber de la vapeur d'eau pendant 3 à 4 semaines à 20°C, elles perdent leur dormance et germent meme & à l'obscurité. La rupture de la dormance est en relation directe avec la pression de la vapeurd'eau de l'atmosphére dans laquelle les semences sont conservées; une bonne aération est nécessaire pour que le processus se déclanche. Si les semences absorbent de l'eau à l'état liquide, la rupture de dormance est beaucoup moindre que celle de semences conscrvées dans une atmosphére saturée. Un effet analogue est observé lorsque les semences sont ententes dans un sol ayant atteint sa capacity au champ. Les résultats indiquent qu'un certain degriS d'imbibition, sous de bonnes conditions d'changes gazeux. est important pour la rupture de la dormance. Comme hypothtése, il est proposé que la plus grande partie de la population reste dormante lorsqu'il n'y a pas assez d'oxygene disponible pour la semence imbibeée. Le faible taux d'absorption d'oxygéne pourrait étre du à sa fuible diffusion à travers l'enveloppe saturée d'eau de la semence (pour celles qui absorbent l'eau à I état liquide) ou à un bas niveau d'oxygene dans Tatmosphére environnante (cas d'un sol à la capacityé au champ). Un des rôles possibles de l'oxygéne pourrait être d'oxyder les inhibiteurs presents dans les semences. Das Brechen der Keimruhe in Samen von Datura ferox ah ein Effekt der Wasseraiifnahme Samen von Datura ferox keimen nicht, wenn sie bei Dunkelheit gehalten werden; auch nicht, wenn sie zuvor 24 Monate trocken lagerten. Wenn sie bei 20°C, 3 bis 4 Wochen tang Wasserdampf aufnehmen, verlieren sie die Keimhemmung und keimen sogar im Dunketn. Zwischcn dem Brechen der Keimruhe und dem Damptdruck der Luft in der sie gelagert werden, besteht eine direkte Beziehung. Fur diesen Vorgang ist eine gute BelCiflung Vorausselzung. Wenn die Samen flijssiges Wasser aufnehmen, ist der Verlust der Keimhemmung wesentlich geringer als wenn sie in einer gesättigten Atmosphäre gelagert werden. Eine ähnliche Wirkung wird beobachtet. wenn die Samen im Boden bei Feldkapazität gelagert werden. Die Ergebnisse zeigen, dass für das Brechen der Keimruhe ein bestimmtes Mass der Aufnahme bei ausreichendem Gasaustausch wichtig ist. Als cine Hypothese wird vorgeschlagen, dass die meisten der Population dormant bleiben, wenn für die mil Wasser vollgesaugten Samen nicht ausreichend O2 verfügbar ist. Der geringe Zutritt an O2 konnte auf die mässige Diffusion durch die wassergesättigte Samenschale (Samen die fliissiges Wasser aufnehmen), oder auf einen geringen O2-Gehalt in der umgebenden Luft (Boden bei Feldkapazität) zurückzuführen sein. Eine der möglichen Bedeutungen die dem O2 zukommen, könnte in der Oxidation des bzw. der Hemmstoffe der Samen liegen. 相似文献
88.
89.
Irina GARCIA-ISPIERTO M. Angels ROSELLó Fabio DE RENSIS Fernando LóPEZ-GATIUS 《The Journal of reproduction and development》2013,59(6):544-548
This study compared the efficiency of a five-day or standard (nine-day)
progesterone-based regimen combined with equine chorionic gonadotrophin (eCG) in a
fixed-time AI (FTAI) protocol for dairy cows. The data examined were derived from
3577 inseminations conducted in three dairy herds. Animals with no estrus signs
detected over 21 days were randomly assigned to a PRID-9 or PRID-5 group. Cows in
each group received a progesterone intravaginal device (PRID) for 9 or 5 days,
respectively, PGF2α and eCG on PRID removal, and GnRH 48 h later.
Fixed-time AI was performed 12 h after the GnRH dose. Cows artificially inseminated
following spontaneous estrus during the study period were considered as controls.
Based on the odds ratio, the likelihoods of animals in PRID-9 in the warm (conception
rate [CR] of 22.3%) and cool (32% CR) periods, and control animals in the warm period
(26.6% CR) becoming pregnant were reduced (by factors of 0.6, 0.3 and 0.4,
respectively) compared with the control animals in the cool period (CR of 43.7%). The
risk of a twin pregnancy was higher (51.4%) for cystic PRID-9 cows (by a factor of
3.6) and lower (9.9%) for cyclic PRID-5 animals (by a factor of 0.4) compared with
the PRID-9 cyclic cows. These findings indicate that the proposed protocol achieves
similar results during the cool or warm season to those obtained when AI is conducted
at spontaneous estrus during the cool season. In addition, PRID-5 reduced twin
pregnancy compared with PRID-9. 相似文献
90.
R. DE COSTER A.-D. A. Y. DEGRYSE P. VAN DIJK L. A. A. OOMS E. LAGERWEIJ 《Journal of veterinary pharmacology and therapeutics》1987,10(3):227-232
R 8110, an imidazole derivative, was shown to be clinically superior to etomidate for induction and maintenance of anaesthesia in dogs. The present study compared the effects of intravenous (i.v.) R 8110, etomidate and Ringer solution on cortisol biosynthesis by the adrenal gland in seven male labradors. A tetracosactide challenge was carried out 30 min after the i.v. injection of 3 mg/kg of both drugs and after i.v. Ringer solution (1 ml/kg). Etomidate and R 8110 both suppressed the cortisol response to tetracosactide almost completely and increased the plasma 11 beta-deoxycortisol levels more than 20 fold. Maximal 11 beta-deoxycortisol values were reached 120 min after R 8110, and not less than 300 min after etomidate. Plasma 17 alpha-hydroxyprogesterone and testosterone concentrations did not differ between placebo and R 8110 treatment, but they decreased after etomidate. These results indicate that the effects of R 8110 on steroid biosynthesis in dogs are less pronounced than those of etomidate and are largely limited to a temporary inhibition of the 11 beta-hydroxylase in the adrenal gland. 相似文献