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101.
Epigenetic programs controlling development of the female reproductive tract (FRT) are influenced by the effects of naturally occurring bioactive agents on patterns of gene expression in FRT tissues during organizationally critical periods of foetal and perinatal life. Aberrations in such important cellular and molecular events, as may occur with exposure to natural or manmade steroid or peptide receptor-modulating agents, disrupt the developmental program and can change the developmental trajectory of FRT tissues, including the endometrium, with lasting consequences. In the pig, as in other mammals, maternal programming of FRT development begins pre-natally and is completed post-natally, when maternal effects on development can be communicated via signals transmitted in milk. Studies involving relaxin (RLX), a prototypic milk-borne morphoregulatory factor (MbF), serve as the basis for ongoing efforts to identify maternal programming events that affect uterine and cervical tissues in the neonatal pig. Data support the lactocrine hypothesis for delivery of MbFs to neonates as a specific consequence of nursing. Components of a maternally driven lactocrine mechanism for RLX-mediated signalling in neonatal FRT tissues, including evidence that milk-borne RLX is delivered into the neonatal circulation where it can act on RLX receptor (RXFP1) -positive neonatal tissues to affect their development, are in place in the pig. The fact that all newborn mammals drink milk extends the timeframe of maternal influence on neonatal development across many species. Thus, lactocrine transmission of milk-borne developmental signals is an element of the maternal epigenetic programming equation that deserves further study. 相似文献
102.
Objective To assess the validity of claims that heavy metal contamination from an open-cut mine caused the death of 226 cattle on a nearby farm over a period of 18 months, and to investigate other possible contributing factors.
Procedure A retrospective assessment of previous investigations combinded with additional chemical analyses.
Results Extensive chemical analyses produced no evidence of heavy metal contamination associated with the mine. Analysis of bones indicated exposure to fluoride in greater than normal amounts. The main source of fluoride seems to have been gypsum that was included in a feed supplement and also ingested from fertiliser dumps on paddocks. The gypsum itself may have contributed significantly to the ill health. Other factors probably affected some classes of animals, notably the young calves.
Conclusions What originally seemed to be a disease problem of single aetiology probably was an expression of interacting multifactorial causes. This investigation has highlighted the potential toxicity of gypsum to livestock and the need for further studies to establish its basis. 相似文献
Procedure A retrospective assessment of previous investigations combinded with additional chemical analyses.
Results Extensive chemical analyses produced no evidence of heavy metal contamination associated with the mine. Analysis of bones indicated exposure to fluoride in greater than normal amounts. The main source of fluoride seems to have been gypsum that was included in a feed supplement and also ingested from fertiliser dumps on paddocks. The gypsum itself may have contributed significantly to the ill health. Other factors probably affected some classes of animals, notably the young calves.
Conclusions What originally seemed to be a disease problem of single aetiology probably was an expression of interacting multifactorial causes. This investigation has highlighted the potential toxicity of gypsum to livestock and the need for further studies to establish its basis. 相似文献
103.
Effects of body condition score (BCS) on steroid‐ and eicosanoid‐metabolizing enzyme activity in various mare tissues during winter anoestrus 下载免费PDF全文
MPT Owen EN Ferjak CA Cavinder KJ McCarty KC Yankey CG Hart DD Burnett TTN Dinh CO Lemley 《Reproduction in domestic animals》2018,53(2):296-303
The objective of this study was to determine the activity of steroid‐ and eicosanoid‐metabolizing enzymes in horses with varying BCSs. The BCSs of twenty non‐pregnant, anoestrous mares were determined prior to euthanasia, and tissue samples were collected from the liver, kidney, adrenal gland, ovary and endometrium. Cytochrome P450 1A (CYP1A), 2C (CYP2C), 3A (CYP3A) and uridine 5′‐diphospho‐glucuronosyltransferase (UGT) activities were determined using luminogenic substrates. The MIXED procedure of SAS was used to test the effect of BCS on enzyme activity and differences between tissues. Activity of CYP1A in adrenals was increased (p ≤ .05) in BCS 5 versus BCSs 4 and 6. Activity of CYP1A in the liver was increased (p = .05) in BCS 4 versus BCSs 5 and 6. Activity of CYP1A was 100‐fold greater (p < .0001) in the liver than in the adrenal, ovary and kidney. Activity of CYP2C was 100‐fold greater (p < .0001) in the liver than in the adrenal, ovary and endometrium. Activity of CYP3A was only detectable in the liver. Activity of UGT in the kidney was decreased (p = .02) in BCS 4 versus BCSs 5 and 6. Activity of UGT was threefold greater (p < .0001) in the liver than in the kidney, whereas activity of UGT was ninefold greater (p < .0001) in the kidney than in the ovary and endometrium. In general, BCS did not alter the activity of steroid‐ and eicosanoid‐metabolizing enzymes in horses. However, tissue differences in these enzymes indicated abundant hepatic metabolism in horses, which is similar to other livestock species. 相似文献
104.
105.
The Recipients' Parity Does Not Influence Their Reproductive Performance Following Non‐Surgical Deep Uterine Porcine Embryo Transfer 下载免费PDF全文
EA Martinez A Nohalez CA Martinez I Parrilla J Vila I Colina M Diaz J Reixach JL Vazquez J Roca C Cuello MA Gil 《Reproduction in domestic animals》2016,51(1):123-129
With the development of the non‐surgical deep uterine (NsDU) embryo transfer (ET) technology, the commercial applicability of ET in pigs is now possible. There are, nevertheless, many factors that influence NsDU‐ET effectiveness that need to be addressed. The aim of this study was to evaluate the effects of the weaned recipients' parity on fertility and prolificacy following NsDU‐ET. The recipients (n = 120) were selected based on their reproductive history and body condition and grouped into three categories according to their parity: primiparous sows, sows of parity 2 and sows of parities from 3 to 5. Thirty fresh embryos (morulae and unhatched blastocysts) were non‐surgically transferred into one uterine horn of each recipient. It was possible to insert the NsDU‐ET catheter through the cervix along a uterine horn in 98.3% of the recipients. The parity had no influence on the difficulty grade of the insertions or on the percentage of correct insertions. The cervix and uterine wall were not perforated during the insertions, and vaginal discharge was not observed after transfer in any of the recipients. There were no differences in the pregnancy rates (74.8%), farrowing rates (71.2%) or litter sizes (9.6 ± 3.3) between groups. Also, there were no differences between groups regarding to the piglets' birthweights or piglet production efficiency. In conclusion, these results demonstrate that weaned sows from parity 1 to 5 are appropriate to be used as recipients in NsDU‐ET programs, which increase the possibilities for the utilization of ET in the recipient farms. 相似文献
106.
107.
绥化市北林区农机事业在黑龙江省起步比较早,与全省其他市县一道,通过近两代农机人的共同努力,积累了丰富的工作经验。为此,对改革开放以来北林区农机工作进行较系统的总结,旨在为今后优化农机化发展决策提供参考. 相似文献
108.
109.
对同一头混合柄瘤蚜茧蜂雌蜂连续观察5 d,比较其对蚕豆蚜若蚜和成蚜的选择,并观察了子代蜂的发育特性。结果表明:5日龄蜂对不同虫龄蚜虫的寄生率无显著差异,子代蜂羽化率和雌性比亦无显著差异,但寄生2、3龄若蚜的子代雌蜂体型显著大于寄生其他蚜虫的子代雌蜂,寄生3龄若蚜的子代雄蜂显著大于寄生成蚜的子代雄蜂。在其他日龄(1~4)蜂中,1、4日龄蜂对不同龄若蚜的寄生率无显著差异,但均高于对成蚜的寄生,2、3日龄蜂对2龄若蚜的寄生偏好显著高于对更高虫龄的寄生;3日龄蜂的子代蜂羽化率在各虫龄蚜虫之间无显著差异,其他日龄蜂寄生低龄若蚜的子代羽化率高于寄生较高虫龄蚜虫;寄生中间龄期若蚜(3、4龄)的子代蜂雌性比显著高于寄生1龄或成蚜的子代蜂;1日龄蜂子代雌蜂体型在不同虫龄蚜虫间无显著差异,但2~4日龄蜂寄生2、3龄若蚜的子代雌性体型大于寄生1龄、4龄或成蚜的子代雌蜂;1、2日龄蜂的子代雄蜂体型在各虫龄蚜虫间无显著差异,3、4日龄蜂寄生中间龄期若蚜的子代雄性体型大于寄生1龄若蚜或成蚜。根据本研究结果推测,与低龄蜂相比高龄蜂对寄主品质要求更高,其幼虫对寄主的调节能力更强。 相似文献
110.
MB Vieira I Bianchi EM Madeira VFB Roll CA Oliveira P Viau I Pivato NC Severo FAB Del Pino A Schneider MN Corrêa 《Reproduction in domestic animals》2010,45(6):1110-1113
This study aimed to evaluate the effect of the exogenous recombinant bovine somatotropin (rbST) on plasma concentrations of insulin‐like growth factor I (IGF‐I), insulin and semen quality of bulls. Twenty bulls (Aberdeen Angus and Brangus) were divided by breed into two groups. Placebo group was injected with NaCl 0.9% (s.c.) and treatment group with rbST (s.c., 500 mg) at days 0 and 14 of the experiment. Immediately after semen collection, blood samples were taken on days 0, 14, 28, 42 and 56 of the experiment. Semen was also collected on day 70 of the experiment. Evaluation of sperm motility was performed at pre‐freezing and post‐thawing stage, whereas assessment of sperm membrane integrity was performed after freezing and thawing. Analysis of data revealed that the effect of treatment and treatment‐by‐collection day on plasma concentrations of IGF‐I and insulin was not significant. However, mean plasma concentrations of IGF‐I and insulin were affected (p < 0.0001) by days of blood sampling. Effect of treatment and treatment‐by‐collection day on motility of spermatozoa was similar (p > 0.05) at pre‐freezing and post‐thawing stage. Intactness of plasmalemma and tail membrane of spermatozoa at post‐thawing stage was higher (p < 0.05) in rbST‐treated group than in control. In conclusion, rbST did not affect plasma concentrations of IGF‐I and insulin, however, it did improve post‐thaw sperm membrane integrity. 相似文献