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排序方式: 共有47条查询结果,搜索用时 28 毫秒
1.
营养条件对光滑球拟酵母发酵生产丙酮酸的影响   总被引:11,自引:2,他引:9       下载免费PDF全文
丙酮酸是多种氨基酸、维生素及其它有用物质的重要前体,广泛应用于化工、制药及农用化学品工业。能够直接发酵生产丙酮酸的菌种主要有Acinetobacter[1],Enterobacter[2],Enterococcus[3],Escherichia[4],Agaricu?..  相似文献
2.
有蹄类动物营养状况的测定方法及其评价   总被引:9,自引:0,他引:9       下载免费PDF全文
营养状况对于动物的生存和繁殖至关重要,是有蹄类动物种群管理的前提条件之一。文章综述了有蹄类动物营养状况的几种主要测定方法,简要介绍了这些方法的理论前提、基本模型、适用范围,并评价了它们的优缺点及如何提高其准确性的方法和途径。  相似文献
3.
Starved Japanese flounder Paralichthys olivaceus larvae were characterized by relatively lower levels of RNA content throughout their early life stages. Significant differences in the RNA: DNA ratios were found between fed and starved fish, and appeared to increase as starvation proceeded. Ontogenetic changes in RNA: DNA ratios were clearly observed during metamorphosis, especially decreasing during the period from the late-metamorphic to postmetamorphic stages. The criteria established from these laboratory experiments, were applied to the nutritional condition of wild larvae and juveniles collected in Wakasa Bay, Sea of Japan in 1994 and 1995 by measuring RNA and DNA content. Starved fish were mainly found in stage I (settling stage) fish during the late season of settlement in 1995. This suggests that starvation could be associated with settlement in Japanese flounder.  相似文献
4.
Nucleic acid assessments and especially the RNA/DNA ratio are used widely as indices of growth rate or nutritional condition of larval fish. Methodological aspects are considered with the aim of defining a most reliable analytical procedure. Laboratory calibrations can give conflicting results, but general and common features may be drawn from a global examination. A high variability of RNA content, and thus RNA/DNA ratio, was revealed by estimates at the individual level and seems to be more related to feeding condition in late larval or juvenile stages than in yolk-sac and first-feeding larvae. An alternative is suggested, based on the relative DNA content which appears more stable and sensitive to starvation during these early stages. The consistency of such a pattern is strongly supported by findings about regulation of ribosomal RNA content of tissues, and especially white muscle, by nutrition. Determination of a threshold founded on a simple observation of morphological development stages is proposed as a base to define the best way to assess the larval nutritional condition. Some field applications are reviewed briefly. Finally an appraisal of the advantages and drawbacks of the different nucleic acid-based indices is attempted, which permits delineation of some prospects for future research.  相似文献
5.
长江中游四大家鱼仔鱼营养状况的初步研究   总被引:3,自引:1,他引:2       下载免费PDF全文
通过形态观察,食性分析及消化系统组织学检测,对长江中游四大家鱼仔鱼的营养状况进行了初步评价,仔鱼具有匀称,消瘦和很消瘦三种体型,空肠率较高,草鱼,鲢,青鱼和鳙分别为45.16%-72.13%,30%-40.01%,31.25%-67.65%和87.50%,依据肝胰脏的肠和组织学特征,可以将天然仔鱼的营养水平划分为很好,较好的饥饿三种,1998年采自九江江段的样本中,遭受饥饿的草鱼,鲢,青鱼和鳙分别为40%,48.15%,46.15%和60%。  相似文献
6.
Of three common macrourids Coryphaenoides armatus and Coryphaenoides yaquinae were collected from 1995 to 1998 at an abyssal station, c . 220 km west of Point Conception, California in the north-east Pacific (4100 m depth). Coryphaenoides acrolepis was collected from 1997 to 1998 in the San Diego Trough (1200 m depth). Energy storage in all three species was primarily in the liver, which was up to 56% lipid (wet mass) and up to 96% triglyceride. No seasonal variation in nutritional condition was found for C. armatus or C. yaquinae . There was, however, a significant increase in muscle water content and liver lipid content and a significant decline in muscle lactate dehydrogenase activity for C. armatus between 1996 and 1998. Potential mechanisms for these interannual shifts are proposed. No seasonal variation in parameters was found for C. acrolepis but a small seasonal periodicity in feeding activity may have existed. The seasonal deposition of phytodetritus in the deep sea is of little or no consequence to these fishes.  相似文献
7.
Larvae of Coregonus spp. were reared in the laboratory under different temperature (4, 6 and 8°C) and feeding conditions ( ad libitum , limited, with starvation intervals). Their RNA/DNA ratios were determined with a highly sensitive fluorescence technique. After resorption of their yolk reserves (about 2 weeks after hatching), well fed larvae (RNA/DNA >2.5) could be significantly distinguished from larvae reared under limited food supply (RNA/DNA < 2.5), both at the 6 and 8°C levels. At 4°C, no differences due to the feeding regime were found. During a second series of experiments, larvae were affected by an intestinal disease, which was caused by the ingestion of unsuitable copepod plankton. This disease provoked high mortality, decreased growth and RNA/DNA ratios which were almost as low as in temporarily starved larvae from the first series. Coregonid larvae sampled in Lake Constance during spring 1990 showed RNA/DNA ratios which were unexpectedly low when judged on the basis of mean body length and average ambient temperature. It was obvious from macroscopic observations that some of these wild larvae were severely attacked by the intestinal disease. The low RNA/DNA ratios in field samples are, therefore, interpreted as a sublethal result of this disease.  相似文献
8.
Fluctuating asymmetry (FA) has been used as a measure of developmental stability and may indicate individual phenotypic or genotypic quality. Using water boatmen (Callicorixa vulnerata) from a natural population, we examined the relationship between tarsal FA (tarsal spine number, tarsal length) and indices of body condition in two habitats. We used body weight and residual body weight (controlling for body length) as indices of condition because experimental food deprivation in water boatmen led to a reduction in each. We detected a negative relationship between FA and both indices of condition in two ecologically distinct pond habitats. We predicted this association was due to a negative relationship between FA and competitive feeding ability. Consequently, we examined associations between survival time and tarsal FA in C. vulnerata under resource-limited laboratory conditions. Univariate analyses revealed a negative correlation between survival and tarsal FA in each trait. Inclusion of survival time, body length, gender, tarsal spine number, tarsal length, and measures of FA into multivariate analyses revealed a negative correlation between survival and FA. Individuals with the greatest survival had higher nutritional condition than individuals that succumbed early in the experiment. Asymmetric individuals may suffer a foraging handicap as a result of the use of tarsi in feeding or they may be of poor genetic quality. Our results suggest elevated FA may limit resource acquisition and are consistent with the use of FA as a measure of fitness.  相似文献
9.
Mass spawning of corals provides a large seasonal pulse of high-energy prey that potentially benefits reef fish that are capable of capturing and digesting coral propagules. This study examines the range of fish species that consume coral propagules and also tests whether reef fish experience a significant increase in physiological condition when feeding on coral propagules. Thirty-six species of diurnal reef fish were seen to consume coral propagules released during mass coral spawning. Stomach content analyses of three reef fish species (Pomacentrus moluccensis, Abudefduf whitleyi, and Caesio cunning) revealed that both P. moluccensis and A. whitleyi feed almost exclusively on coral propagules during mass coral spawning. Fish feeding extensively on coral propagules also amassed considerable lipid stores, which could greatly improve the quality and survivorship of their progeny. In contrast, C. cunning consumed only very small quantities of coral propagules, and showed no detectable change in lipid stores during the course of the study. This study provides the first direct evidence that reef fish benefit from mass coral spawning, and reveals a potentially significant trophic link between scleractinian corals and reef fish. Accepted: 9 June 2000  相似文献
10.
茶薪菇菌丝液体培养的营养需求   总被引:1,自引:0,他引:1  
探索茶薪菇菌丝液体培养所需的营养条件,并测定了供试氛源和碳源所培养的菌丝的粗蛋白。结果表明:氨源以玉米浆、蛋白胨最佳;碳源以玉米粉、可溶淀粉最适宜;最佳的碳氮比为20.8:1;有机酸中仅富马酸对其生长有促进作用;磷和锌为菌丝生长的必需矿质元素。  相似文献
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