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排序方式: 共有117条查询结果,搜索用时 31 毫秒
1.
An experimental protocol consisting in the colonisation of pregerminated bean seeds dressed withTrichoderma sp. was used in order to study the mechanisms correlated with the protective effect againstPythium splendens. Seed dressed with TH-11 (T. koningii) for 24 h presented a higher protective effect and a higher level of seed colonisation as compared to those dressed with TH-13 (T. longibranchiatum). The levels of seed coat colonisation by TH-11 and TH-13 was shown to be correlated with the carboxymethylcellulase activity, as measured in the seed coats retreived from germinating dressed bean seeds. The seed coat colonisation was also associated with an increased activities of endo-1,3-k8346631/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-glucanase and endochitinase measured in seed extracts, and an inhibitory effect of seed extracts onPythium sporangia germination. Pretreatment of TH-13-dressed seeds with a commercial cellulase improved all parameters mentioned above, thus suggesting a role of cellulase activity in the colonisation process and the linked protective effect. The possible role of hydrolytic enzymes in the protective effects is discussed.  相似文献   
2.
This paper reports the milk protein polymorphism, the allele frequencies of variants and the possible linkages among various combinations of milk protein phenotypes in the Kangayam cattle of south India. Milk samples from 156 Kangayam cows were typed by starch gel and polyacrylamide gel electrophoresis for caseins and whey proteins, respectively. All the four milk protein components studied, k7w/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">s1-casein, k7w/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-casein, k7w/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-lactoglobulin and k7w/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-lactalbumin, exhibited polymorphism with high allele frequencies of 0.9231±0.0151 for k7w/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">s1-casein C, 0.9263±0.0148 for k7w/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-casein A, 0.9135±0.0159 for k7w/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-lactoglobulin B and a relatively high frequency of 0.6218±0.0275 for k7w/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-lactalbumin A. The mean heterozygosity estimated over all the four milk protein loci was 0.2420. Genetic equilibrium was observed among all the loci studied, except k7w/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-lactalbumin. Linkage analysis confirmed the non-independence between k7w/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">s1- and k7w/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-caseins and between caseins and k7w/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-lactalbumin phenotypes.  相似文献   
3.
Interactions between Plasmopara helianthi, Glomus mosseae and two plant activators DL-k61581787603lqq3/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-amino-n-butyric acid (BABA) and CGA 245704 (acibenzolar-S-methyl (BTH)) in sunflower plants susceptible to downy mildew were studied in four experiments using different methods of treatment and pathogen inoculation. Both chemicals were applied as soil drenches and foliar sprays, whereas P. helianthi infection was obtained by root and cotyledon inoculations of the seedlings. Soil drenches at the rates of 50 and 100k61581787603lqq3/xxlarge8201.gif" alt="thinsp" align="MIDDLE" BORDER="0">mgk61581787603lqq3/xxlarge8201.gif" alt="thinsp" align="MIDDLE" BORDER="0">kg–1 soil of BABA and BTH given 1 and 3 days before P. helianthi inoculation, respectively to mycorrhizal plants, provided moderate protection against the pathogen (about 50–55%). Morphological changes and decrease in mycorrhizal colonization in roots of BTH-treated plants and in BTH-treated mycorrhizal plants were also observed. Delay in the emergence and reduction of the root systems were more evident at the highest concentration but decreased with time. These effects were absent with the BABA treatment.Foliar spray treatment of BABA and BTH, applied at 4000 and 200k61581787603lqq3/xxlarge8201.gif" alt="thinsp" align="MIDDLE" BORDER="0">µgk61581787603lqq3/xxlarge8201.gif" alt="thinsp" align="MIDDLE" BORDER="0">ml–1, respectively (1 day post-inoculation) to mycorrhizal plants provided good protection (about 80%) against P. helianthi foliar infections. No effects on mycorrhizal colonization or on root systems were observed. In vitro tests on the effect of the compounds on the mycorrhizal fungus showed that the germination of G. mosseae sporocarps increased with BABA treatment whereas it was greatly inhibited by BTH treatment.  相似文献   
4.
徐世敏 《青海草业》2006,15(1):16-17,21
对不同退化程度下的矮嵩草和高山嵩草无性系繁殖特性进行了初步研究。结果表明不同退化程度下两种嵩草有性繁殖能力较弱,种子生产能力低,其中中度退化草地上高山嵩草每有效穗最高只产生2粒种子,重度退化草地矮嵩草每有效穗最高只产生3.6粒种子。  相似文献   
5.
The protected structure of k1gq/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-oxoacteoside (tomentoside A), 2-oxo-2-(3,4-dihydroxyphenyl)ethyl 3-O-(2,3,4-tri-O-acetyl-k1gq/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-l-rhamnopyranosyl)-4-O-caffeoyl-k1gq/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-d-glucopyranoside 14 was synthesized in 14% overall yield in 11 steps, starting from d-glucose for biological and medicinal studies of phenylpropanoid glycosides. The first step was the preparation of a 3-O-rhamnopyranosyl disaccharide sugar core 2 from a suitably protected rhamnosyl trichloroacetimidate 10 and glucose derivative (diacetone-d-glucose 1) in 71% yield. To the glucose moiety of this sugar core, several protection/deprotection procedures were performed sequentially to obtain a fully acetylated sugar core 7 with a 4-OH group on the glucose moiety, in 57% yield in five steps. Thereafter, to the 4-OH group of the glucose moiety, selective 4-O-caffeoylation was achieved by proton-transfer esterification with 3,4-di-O-allylcaffeic acid 16 to give the caffeoyl disaccharide 11 in 97% yield. Then, it was converted to trichloroacetimidate 13 for a glycosylation donor in 90% in two steps. Finally, anomeric glycosylation was conducted with 2-oxo-2-(3,4-di-allyloxyphenyl)ethyl alcohol 19 with catalytic amounts of BF3·Et2O to give 2-oxo-2-(3,4-di-allyloxyphenyl)ethyl 2,6-di-O-acetyl-3-O-(2,3,4-tri-O-acetyl-k1gq/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-l-rhamnopyranosyl)-4-O-(3,4-di-allyloxycaffeoyl)-k1gq/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-d-glucopyranoside 14 in 60% yield. Deprotected intermediates of compounds 2, 11, 14, and 19 which were obtained in high yield would be useful for biological and medicinal studies of phenylpropanoid glycosides.Part of this study was presented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, April, 2002  相似文献   
6.
7.
A modified synthetic method for phenolick56l8133101k/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-O-4 lignin substructure model dimers was developed involving protection of the phenolic hydroxyl group of acetophenons with benzoyl chloride, bromination with 4-dimethylaminopyridiniumbromide perbromide, condensation with phenols in the presence of 18-crown-6-ether, condensation with paraformaldehyde, reduction with NaBH4 and debenzoylation. This method results in shorter reaction times and increasing yields without the application of strict anhydrous and drastic conditions or chloric solvents. This alternative route could be applied to thek56l8133101k/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-O-4 dilignol syntheses of four combinations of guaiacyl and syringyl derivatives.  相似文献   
8.
The effects of (ip, 10 injections over 20 days) of melatonin (75 k456/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">g 100 g–1 BW), the serotonin (5-HT)-synthesis blocker, para-cholorophenylalanine (p-CPA, 10 mg 100g–1 BW) and the catecholamine-synthesis blocker, k456/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-methylparatyrosine (k456/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-MPT, 10 mg 100 g–1 BW) on gonadotropin (GTH) secretion and ovarian activity were studied in Heteropneustes fossilis during late preparatory to early prespawning (April–May). The treatments resulted in significant reductions of plasma GTH and estradiol-17k456/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0"> levels, the gonadosomatic index, frequency distribution of vitellogenic and postvitellogenic oocytes, and ovarian and serum 32p-labelled alkali-labile phosphoprotein (a marker of vitellogenic activity). Most of the oocytes were nonvitellogenic or had undergone atretic changes. The hepatic 32-phosphoprotein content increased significantly over the saline control value. The effects were similar and pronounced in the p-CPA and melatonin-treated groups but were moderate in the k456/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-MPT-treated group. Hypothalamic 5-HT content and turnover were significantly inhibited in the p-CPA and melatonin-treated groups but the content and turnover of catecholamines were not. The k456/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-MPT treatment decreased significantly the content and turnover of dopamine (DA), noradrenaline (NA), and adrenaline (A) but did not influence the 5-HT content or turnover. These results suggest that 5-HT, NA and A are stimulatory to GTH secretion and that melatonin may act on the serotonergic system to inhibit the pituitary-gonadal axis.to whom correspondence should be addressed.A part of the results was presented at the International Workshop on Pineal gland: Its molecular signals and published as an abstract in Neuroendocrinol. Lett. 14: 399 pp., 1992.  相似文献   
9.
实验旨在研究孕酮对蛋鸡CaBP-d28k基因表达的影响。对产蛋高峰期蛋鸡进行孕酮和孕酮受体拮抗剂(RU-486)处理,利用实时荧光定量PCR技术(QRT-PCR),测定在蛋壳形成过程中输卵管子宫部钙结合蛋白(CaBP-d28k)、孕酮受体(PGR)的表达量;同时对血液中钙离子和孕酮浓度变化进行测定。结果表明:孕酮处理后,血液中钙离子浓度显著降低(P<0.05),输卵管子宫部CaBP-d28k表达量也显著降低(P<0.05);孕酮受体拮抗剂处理后,血液中钙离子浓度显著升高(P<0.05),输卵管子宫部CaBP-d28k表达量极显著升高(P<0.01)。结果提示,在蛋壳钙化过程中,孕酮对CaBP-d28k表达和钙离子转运起负调控作用。  相似文献   
10.
8头4~5岁的役用秦川母牛按配对原则分为对照组和试验组。两组牛的精料配方基本相同,但试验组牛饲粮用7.75%的鲁梅克斯K-1杂交酸模粉(以下简称鲁梅克斯K-1)代替对照组中同等重量的小麦麸;对照组牛的粗料全部用干玉米秸,试验组半用60%干玉米秸和40%的玉米秸+鲁梅克斯叶混合青贮料。正试期20d。结果表明:试验组牛的平均日增重为 0.787kg,对照组0.690kg,试验组较对照组牛日增重提高了 14.06%;每增重 1kg活重试验组牛消耗精、粗料分别为2.54kg、5.25kg,对照组半分别为2.90kg、5.50kg,试验组较对照组个节约精料0.36kg、粗料0.25kg;试验组每头牛毛盈利为73.34元,对照组59.40元,前者比后者提高经济效益23.47%。说明在役用母牛饲粮中,用鲁梅克斯粉代替精料中的小麦麸并用玉米秸+鲁梅克斯混合青贮料能获得良好的生产性能和经济效益。  相似文献   
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