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   219篇
  免费   6篇
  国内免费   1篇
林业   20篇
农学   14篇
基础科学   1篇
  54篇
综合类   7篇
农作物   7篇
水产渔业   50篇
畜牧兽医   43篇
园艺   4篇
植物保护   26篇
  2022年   1篇
  2021年   3篇
  2020年   4篇
  2018年   5篇
  2017年   7篇
  2016年   4篇
  2015年   8篇
  2014年   18篇
  2013年   23篇
  2012年   13篇
  2011年   19篇
  2010年   17篇
  2009年   9篇
  2008年   14篇
  2007年   12篇
  2006年   9篇
  2005年   7篇
  2004年   7篇
  2003年   16篇
  2002年   4篇
  2001年   7篇
  2000年   4篇
  1999年   4篇
  1998年   3篇
  1997年   2篇
  1991年   2篇
  1989年   1篇
  1974年   1篇
  1972年   2篇
排序方式: 共有226条查询结果,搜索用时 15 毫秒
91.
92.
Survey on the wild genetic resources of hardy kiwifruit (Actinidia arguta) in Japan was conducted to determine the ploidy variation and its geographic distribution. Among the 127 wild plants collected from different geographic locations, 15 plants were diploid, 87 were tetraploid, and 22 were hexaploid. Additionally, 2 plants were heptaploid and one plant was octaploid. The tetraploid plants were distributed all over the country, whereas the diploid and hexaploid plants were geographically localized, in the warm Pacific hill areas of the south western part and in the deep-snow region of the mid-northern part of Honshu, respectively. The diploid plants could be clearly distinguished from other plants with ploidy variation by the morphological characteristics of the leaf and fruit. Hexaploid plants showed a relatively larger L/D ratio of the leaf blade, a greenish petiole, and pubescence on the petiole and lower leaf vein, whereas the tetraploid plants exhibited a reddish petiole and callose hairs on the vein of the lower leaf surface. Fruit shape of the tetraploid plants varied largely, from round to ellipsoidal, whereas that of the hexaploid plants was mostly ellipsoidal. These results indicate that the hexaploid plants of A. arguta as well as the diploid and tetraploid ones, naturally grow in a certain size of population in the restricted region of Japan.  相似文献   
93.
Cooked spaghetti of various types (fresh, dried, frozen, luncheon, and long‐life spaghetti) was examined for moisture distribution by magnetic resonance imaging (MRI). Moisture content was calculated from spinspin relaxation time (T2) of water proton, based on the correlation between T2 and moisture content of pulverized durum semolina standard gel samples. Boiled samples of dried and frozen spaghetti had a distinct low moisture region at the center, which was not clearly observed in the other types of boiled spaghetti samples. In particular, the moisture content of boiled long‐life spaghetti was almost homogeneous. Texture of cooked spaghetti samples was evaluated using the force‐distance curve of a mechanical property test. For dried and frozen spaghetti, higher force was observed at the region corresponding to the low moisture core compared with the other types. The luncheon spaghetti and long‐life spaghetti showed a lower breaking force and a larger dip after the peak force representing soft and brittle texture caused by moisture homogeneity. These results indicated that MRI could be used for the quality evaluation of cooked spaghetti through imaging of the moisture distribution, which reflects the mechanical property.  相似文献   
94.
Molecular and morphological variation of six perennial and five annual species including domesticated chickpea, C. arietinum, were inferred on the basis of RAPD and S.E.M. seed coat features using three outgroup taxa (Lens ervoides, Lathyrus japonica and Pisum sativum). Of the 66 decamer arbitrary primers tested, eight primers revealed 87 informative fragments. Neighbor-joining cluster analysis using Jaccard's coefficient of similarity on the basis of polymorphic fragments indicated a narrow variation in C. arietinum and recognized two major clusters in the genus Cicer. The first one included four species of sect. Monocicer: C. echinospermum, C. arietinum, C. reticulatum and Iranian material of C. bijugum. The second cluster contained annual and perennial species belonging to sections Chamaecicer, Polycicer and Acanthocicer. The character state of morphological and ecological traits on the RAPD phenogram indicated no monophyletic incision. Our results suggested that the high genetic difference between annual and perennial species might be regarded as a rapid speciation of section Monocicer. Reconsideration of traditional classification of sections Polycicer and Acanthocicer is necessary. The Desi and Kabuli types of C. arietinum could not be separately grouped at the DNA level, and the low level of genetic variation of C. arietinum may result from a bottleneck during the domestication process.  相似文献   
95.
Previous studies have shown the physiological significance of dietary conjugated linoleic acid (CLA) in various experimental animals and in human beings. One of the important problems to better elucidate is the difference between triglyceride (TG) and free (FFA) dietary CLA. Here, using splenocytes, this study assesses how TG- and FFA-CLA modulate immunoglobulin and various cytokine productions. In this study, C57BL/6N mice were fed an experimental diet containing 0% CLA, 0.1 or 1% FFA-CLA, or 0.1 or 1% TG-CLA for 3 weeks. The production of immunoglobulin tended to be up-regulated by 1% FFA-CLA. As a result of protein array analysis using the supernatant from splenocytes cultured with no CLA, 1% FFA-CLA, and TG-CLA, some cytokine production was shown to be remarkably regulated by dietary FFA- and TG-CLA. A total of 32 cytokines were examined, and 11-14 produced cytokines that were 2-fold up-regulated as compared with control for FFA- or TG-CLA, respectively. Especially, the production of IL-9 and MCP-5 and other cytokines was remarkably up-regulated by both FFA- and TG-CLA. In addition, seven cytokines were 2-fold down-regulated by TG-CLA. These data show that there is a slight but significant difference between the functionalities of FFA- and TG-CLA.  相似文献   
96.
Recent studies suggest that nitric oxide (NO), an important signaling and defense molecule in mammals, plays a key role in activating disease resistance in plants. We characterized NO production by tobacco Bright Yellow-2 cells pharmacologically after treatment with INF1, the major elicitin secreted by the late blight pathogen Phytophthora infestans, prepared from Escherichia coli. NO production rapidly occurred within 1h and reached a maximum level 3–6h after the addition of INF1. Carboxy-PTIO, a NO-specific scavenger, abolished INF1-induced NO production in a dose-dependent manner. Pretreatment of protein synthesis inhibitor cycloheximide and protein kinase inhibitor K252a blocked NO production 3–12h after INF1 treatment, indicating that NO production requires de novo protein synthesis and protein phosphorylation. In an investigation of the relations between NO generation and several defense responses induced by INF1, carboxy-PTIO completely suppressed activation of a 41-kDa protein kinase and cell death by INF1. Carboxy-PTIO also suppressed the induction of hypersensitive-related (hsr) genes HSR515 and HSR203J, the expression of which is strongly correlated with the hypersensitive response in plants. The results suggest that NO plays a crucial role in the induction of hypersensitive cell death.  相似文献   
97.
This study was conducted to investigate the mechanism of green liver symptom induction and the effect of dietary taurine supplementation on growth performance in juvenile red sea bream fed non-fishmeal diets based on soy protein concentrate (SPC). Juvenile fish (initial BW 72 g) were fed for 20 weeks on SPC diets supplemented with taurine at levels of 0, 1.0, and 2.0%. In the taurine-unsupplemented SPC diet group, specific growth rate (SGR) and feed conversion ratio (FCR) were significantly inferior (P < 0.001), and incidence of green liver was observed in 70% of fish. In this group, hepatopancreatic and plasma taurine concentrations were lowest (P < 0.05), hepatopancreatic content of bile pigments was highest (P < 0.05), and osmotic tolerance of erythrocytes was inferior (P < 0.05) among the dietary treatment groups. Serum osmolality of all treatment groups was at similar levels. These physiological abnormalities as well as SGR and FCR were improved by dietary taurine supplementation. These results indicate that the mechanism for induction of green liver symptom is bile pigment overproduction due to increased hemolysis because erythrocytes become osmotically fragile due to dietary taurine deficiency. Taurine supplementation of SPC diets is essential for maintaining normal physiological condition and growth performance in juvenile red sea bream.  相似文献   
98.
99.
The effect of algae with different DHA contents used for the enrichment of rotifers on the growth performance, survival, and swim bladder inflation of larval amberjack Seriola dumerili was investigated. Rotifers were enriched with freshwater Chlorella vulgaris containing three levels of DHA (rotifer containing DHA 0.04, 0.60, 1.32?g DHA 100?g?1 DM) and Nannochloropsis (0.04?g DHA 100?g?1 DM; 2.54?g EPA 100?g?1DM). The larvae were fed the enriched rotifers in triplicate from 3?days post-hatch for 7?days in static condition. The same algae used for rotifer enrichment were supplied to the larval tanks. Growth and survival rate of fish fed the rotifers enriched with Nannochloropsis were higher than those of fish fed the rotifers enriched with all three Chlorella treatments. Swim bladder inflation was lowest in fish fed the rotifers enriched with Nannochloropsis. The proportion of EPA was higher in fish fed the rotifers enriched with Nannochloropsis, while that of DHA increased proportionally with the DHA levels in the rotifers enriched with Chlorella. These results suggest that rotifers enriched with Nannochloropsis (EPA-rich rotifers) are effective to enhance growth and survival, but DHA instead of EPA is essential to improve the swim bladder inflation in amberjack larvae.  相似文献   
100.
1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of Japanese whiskey after various aging periods in oak barrels was measured to evaluate the antioxidative effects of whiskey. The activity of the whiskey increased with the aging period with high correlation. The activity of various types of whiskey was measured and shown to be correlated to the potentiation of the GABAA receptor response measured in a previous paper. However, the fragrant compounds in the whiskey which potentiated the GABAA receptor response had low DPPH radical scavenging activity, while phenol derivatives had high radical scavenging activity. The whiskey was extracted by pentane. The aqueous part showed the scavenging activity, whereas the pentane part did not. Thus, both the DPPH radical scavenging activity and the potentiation of the GABAA receptor response increased during whiskey aging in oak barrels, but were due to different components. The whiskey protected the H2O2-induced death of E. coli more than ethanol at the same concentration as that of the whiskey. The changes that occurred in the whiskey during aging may be the reason aged whiskies are so highly valued.  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