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   155篇
  免费   8篇
  国内免费   1篇
林业   16篇
  39篇
综合类   10篇
农作物   2篇
水产渔业   28篇
畜牧兽医   58篇
园艺   2篇
植物保护   9篇
  2022年   1篇
  2021年   8篇
  2020年   7篇
  2019年   3篇
  2018年   3篇
  2017年   3篇
  2016年   4篇
  2015年   7篇
  2014年   6篇
  2013年   13篇
  2012年   8篇
  2011年   17篇
  2010年   8篇
  2009年   4篇
  2008年   10篇
  2007年   9篇
  2006年   10篇
  2005年   8篇
  2004年   6篇
  2003年   9篇
  2002年   8篇
  2001年   3篇
  1999年   1篇
  1997年   1篇
  1995年   1篇
  1989年   2篇
  1987年   1篇
  1983年   1篇
  1978年   1篇
  1974年   1篇
排序方式: 共有164条查询结果,搜索用时 609 毫秒
1.
The seasonal change in petal color and pigmentation of 29 commercial Eustoma cultivars was studied. The flowers are basically divided into four groups according to the major anthocyanidin phenotype in association with petal coloration, i.e., delphinidin (Dp)-based (purple flower), cyanidin (Cy)-based (reddish purple flower), pelargonidin (Pg)-based (pink flower), and none (white flower) groups. The constitution of petal anthocyanidins was not changed by forcing treatment in most of the flowers. Lightness (L*) and chroma (C*, color saturation) showed a change along with the increase/decrease of hue angle difference (ΔH*), thus simultaneously the chromatic tonalities tended to move to redder and bluer, respectively. Floral pigment clustering described two flower groups in a dendrogram, based on anthocyanidin constitutions as phenetic markers, which are apparently the Dp- and Pg-based phenotypes of anthocyanidin syntheses. The Cy-based flowers made a subcluster with the Pg-based flowers, indicating a close relationship in the biosynthesis of the two anthocyanidins, and suggesting the Dp- and Pg-syntheses complement one another.  相似文献   
2.
The pathological effects of copper deficiency (COD) are well known. However, the pathogenesis of cardiomyopathy resulting from COD remains unclear. In this study, aimed to elucidate the pathogenesis of COD-induced cardiomyopathy by examining the morphology of the cardiovascular system in copper-deficient rats using histopathology, immunohistochemistry, and scanning and transmission electron microscopy. Changes detected in the myocardium and interstitium were consistent with those reported for COD. Morphological changes included mesh-like changes in the capillary endothelial cells that appear to be a novel finding in COD-induced cardiomyopathy. These changes are hypothesized to result from abnormal vascular remodeling following damage to the basement membrane and due to the mechanical effects of myocardial contractions. Although cardiomyopathy may be associated with microcirculatory disorders arising from these lesions, further investigations are necessary to demonstrate a causal relationship between the pathogenesis of cardiomyopathy and the contribution of these lesions to disease progression.  相似文献   
3.
This study aimed to identify the genes associated with the development of the rumen epithelium by screening for candidate genes by digital differential display (DDD) in silico. Using DDD in NCBI's UniGene database, expressed sequence tag (EST)‐based gene expression profiles were analyzed in rumen, reticulum, omasum, abomasum and other tissues in cattle. One hundred and ten candidate genes with high expression in the rumen were derived from a library of all tissues. The expression levels of 11 genes in all candidate genes were analyzed in the rumen, reticulum, omasum and abomasum of nine Japanese Black male calves (5‐week‐old pre‐weaning: n = 3; 15‐week‐old weaned calves: n = 6). Among the 11 genes, only 3‐hydroxy‐3‐methylglutaryl‐CoA synthase 2 (HMGCS2), aldo‐keto reductase family 1, member C1‐like (AKR1C1), and fatty acid binding protein 3 (FABP3) showed significant changes in the levels of gene expression in the rumen between the pre‐ and post‐weaning of calves. These results indicate that DDD analysis in silico can be useful for screening candidate genes related to rumen development, and that the changes in expression levels of three genes in the rumen may have been caused by weaning, aging or both. © 2015 Japanese Society of Animal Science  相似文献   
4.
ABSTRACT:   To investigate inheritance of chloroplasts and mitochondria (organelles) in the marine red alga Porphyra yezoensis , cleaved amplified polymorphic sequence (CAPS) profiles of the two strains, TU-2 and KGJ, as parental gametophytes and 44 hybrid sporophytes (i.e. female of TU-2 and male of KGJ) were examined. A carbamyl phosphate synthase small subunit gene ( carA ) and ribosomal protein S11 gene ( rps11 )-small subunit ribosomal RNA gene ( rns ) spacer region were used as molecular markers for the chloroplast and mitochondrial DNAs, respectively. Thirty-eight of 44 (86.4%) conchocelis colonies showed maternal banding patterns, five (11.4%) colonies showed biparental bands and one (2.2%) colony showed paternal bands in CAPS analyses both with chloroplast and mitochondrial markers. These results suggest that organelles of P. yezoensis are inherited uniparentally from the female parent.  相似文献   
5.
Programmed cell death (PCD) in animals depends on caspase protease activity. Plants also exhibit PCD, for example as a response to pathogens, although a plant caspase remains elusive. Here we show that vacuolar processing enzyme (VPE) is a protease essential for a virus-induced hypersensitive response that involves PCD. VPE deficiency prevented virus-induced hypersensitive cell death in tobacco plants. VPE is structurally unrelated to caspases, although VPE has a caspase-1 activity. Thus, plants have evolved a regulated cellular suicide strategy that, unlike PCD of animals, is mediated by VPE and the cellular vacuole.  相似文献   
6.
To clarify the influence of rearing conditions on the growth of various body parts of Japanese macaques (Macaca fuscata), two groups reared under different conditions, i.e., a group born and reared in open enclosures (Enclosure group) and another consisting of macaques born and reared in cages (Caged group), were somatometrically analyzed. Somatometric data on 36 measures of various body parts were collected from 77 males and 92 females. Growth in many body parts was smaller in the Caged group than in the Enclosure group. Body parts that exhibited large incremental increases were more sensitive to differences in rearing space at the infantile growth stage in both sexes. Recovery from delayed growth at the pubertal growth stage was found in many body parts. However, the size of some locomotor elements such as the wrist and hand, and ankle and foot strongly reflected limitations of space and changes due to this were irreversible. Females were more sensitive than males to such differences in rearing conditions. We conclude that open enclosures with ample rearing space are necessary for the innate growth of Japanese macaques to occur.  相似文献   
7.
Strobilurus ohshimae is an edible mushroom, and it specifically forms its fruiting bodies on buried sugi (Cryptomeria japonica) twigs. In this research, we studied lignindegrading activity of S. ohshimae. We isolated 18 strains of S. ohshimae from various regions of Japan, and determined their lignin degradation rates on sugi wood meal medium. All the strains of S. ohshimae degraded approximately 6%–12% of sugi lignin in 30 days, and these lignin degradation rates were 1.5–3 times higher than those of Trametes versicolor, which is a typical lignin-degrading fungus. Among the three main lignin-degrading enzymes, activity of lignin peroxidase and manganese peroxidase was not observed, while 4340U/g of laccase was produced in 30 days. To investigate the effect of wood species on lignin degradation by S. ohshimae, the lignin degradation rate and laccase productivity on sugi wood meal medium were compared with those on beech (Fagus crenata). In T. versicolor, both lignin degradation rate and laccase productivity were higher on beech than on sugi. Conversely, in S. ohshimae, lignin degradation rate and laccase productivity were higher on sugi than on beech. Therefore, it was suggested that coniferous lignin is not always difficult to degrade for the fungi that inhabit softwood. Part of this article presented at the 54th Annual Meeting of the Japan Wood Research Society, Sapporo, August 2004  相似文献   
8.
Endometrial adenocarcinoma in the uterine corpus is a malignant cancer that occurs in menopausal women and aged rodents. Because of the similarities in pathogenesis and morphology of endometrial adenocarcinoma in rodents and humans, prediction of the modes of action (MOA) in uterine carcinogenesis is important for extrapolation of rodent data to humans. Three MOAs have been accepted as major pathways for uterine carcinogenesis in rodents: 1) estrogenic activity, 2) increased serum 17beta-estradiiol (E2) to progesterone (P4) ratio and 3) modulation of estrogen metabolism to produce 4-hydroxyestradiol via P450 induction. Inhibition of estrogen excretion and increased aromatase in situ in the tumor are also a potential pathway. Here, chemicals showing uterine carcinogenicity were chosen from approximately 300 pesticides evaluated in Japan within the past decade, and their mechanisms were predicted using parameters from mechanistic and toxicity studies. Seven pesticides increased uterine tumor formation in rats, and the pathways of 4 pesticides could be predicted based on various mechanistic studies. The MOAs of cyenopyrafen and benthiavalicarb-isopropyl were predicted to be modulation of estrogen metabolism, while those of pyriminobac-methyl and spirodiclofen were predicted to be increased E2 to P4 ratio. The driven pathways of metazosulfuron and isopyrazam could not be predicted using several mechanistic studies. No mechanistic studies have been reported for sedaxane, which has a chemical structure and toxicological profile similar to isopyrazam. Our results indicated that appropriate mechanistic studies are useful for mechanism prediction in risk assessment. From this analysis, a flowchart showing a decision tree for predictive MOAs in uterine carcinogenesis was proposed.  相似文献   
9.
The stand density of a forest affects the vertical distribution of foliage. Understanding the dynamics of this response is important for the study of crown structure and function, carbon-budget estimation, and forest management. We investigated the effect of tree density on the vertical distribution of foliage, branch, and stem growth, and ratio of biomass increment in aboveground tissues; by monitoring all first-order branches of five trees each from thinned and unthinned control stands of 10-year-old Chamaecyparis obtusa for four consecutive years. In the control stand, the foliage crown shifted upward with height growth but the foliage quantity of the whole crown did not increase. In addition, the vertical distribution of leaf mass shifted from lower-crown skewed to upper-crown skewed. In the thinned stand in contrast, the foliage quantity of individual crowns increased two-fold within 4 years, while the vertical distribution of leaf mass remained lower-crown skewed. The two stands had similar production rates, numbers of first-order branches per unit of tree height, and total lengths of first-order branches. However, the mortality rate of first-order branches and self-pruning within a first-order branch were significantly higher in the control stand than in the thinned stand, which resulted in a higher ratio of biomass increment in branch. Thinning induced a higher ratio of biomass increment in foliage and lower in branch. The increased foliage quantity and variation in ratio of biomass increment after thinning stimulated stem growth of residual trees. These results provide information that will be useful when considering thinning regimes and stand management.  相似文献   
10.
Blood total antioxidant capacity (TAC) has become a key bio‐marker for animal health. Forest‐grazing cattle are known to forage various native plants that have high TAC. This study evaluated differences of plasma TAC between forest‐grazing (FG) and pasture‐grazing cattle (PG). Experiment 1 monitored the plasma TAC levels of 32 Japanese Black cattle. The level in PG did not change throughout the grazing period. However, that in FG, which increased from summer, was significantly higher than that in PG through fall (P < 0.05). In experiment 2, we used nine Japanese Black heifers and investigated their blood antioxidant parameters and the TAC in plants that the cattle consumed in late June and September. The plasma TAC levels in FG were significantly higher than those in PG in both periods (P < 0.05). Plasma levels of lipid peroxidation in FG tended to be lower than that in PG (P = 0.098). Furthermore, the TAC levels in various species of shrubs and trees consumed by FG were higher than those in pasture grasses. Results of this study show that plasma TAC of grazing Japanese Black cattle in forestland increase from summer through fall.  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