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   134篇
  免费   7篇
林业   5篇
农学   7篇
  33篇
综合类   10篇
农作物   3篇
水产渔业   26篇
畜牧兽医   50篇
园艺   4篇
植物保护   3篇
  2022年   5篇
  2021年   3篇
  2020年   1篇
  2019年   1篇
  2018年   3篇
  2017年   5篇
  2016年   4篇
  2015年   3篇
  2014年   4篇
  2013年   11篇
  2012年   9篇
  2011年   15篇
  2010年   4篇
  2009年   7篇
  2008年   12篇
  2007年   8篇
  2006年   8篇
  2005年   7篇
  2004年   5篇
  2003年   3篇
  2002年   5篇
  2000年   4篇
  1999年   5篇
  1998年   1篇
  1994年   1篇
  1991年   1篇
  1979年   4篇
  1978年   1篇
  1975年   1篇
排序方式: 共有141条查询结果,搜索用时 15 毫秒
31.
We evaluated the applicability of a simple passive sampling method to quantify HNO3(g) in ambient air. The method has the advantages of not only ease of operation but also low cost. A sampling velocity of 214 m day?1 was determined based on the concentration of HNO3(g) measured by the four-stage filter-pack method at nine sites located within a 250?×?250-km area in Japan. This sampling velocity was applied at sites located outside of area to verify the applicability and accuracy of the simple passive sampling method. The variation in the results for the application of the sampling velocity ranged from 0.39 to 0.95. The simple passive sampling method should be applied to sites with different meteorological conditions, and the obtained data should be used to obtain more significant information and/or to indicate the need for further developments in the methodology.  相似文献   
32.
The hepatic mitochondrial carnitine palmitoyltransferase (CPT) activity was measured by fluorimetric assay in dairy cows with or without fatty liver. CPT activities in 13 lactating cattle and in 6 non-lactating cows were 304.4±86.6 mol CoA/min per g protein and 169.3±84.8 mol CoA/min per g protein, respectively. This difference was significant (<0.05). CPT activities in early lactation (0–110 days after calving), mid-lactation (111–220 days after calving) and late lactation (over 220 days after calving) were 278.9±68.0, 312.4±124.1 and 320±59.3 mol CoA/min per g protein, respectively. There was no significant difference between the values at different stages of lactation. The CPT activity in 10 lactating cows with fatty liver unrelated to calving was 201.3±80.0 mol CoA/min per g protein. CPT activity in 10 cattle with fatty liver was significantly lower than that in normal lactating cattle. Based on these findings, clinical fatty liver unrelated to calving appears to be associated with a decrease in hepatic CPT activity.  相似文献   
33.
Intracerebral microdialysis combined with electroencephalographic recordings was performed on 4 dogs of a familial idiopathic epileptic Shetland sheepdog colony to identify the kinds of neurotransmitters responsible for seizure activity. Immunohistochemistry using glutamate (Glu), glutamate transporter (GLT-1 and GLAST), and glutamine synthetase (GS) antibodies was also carried out on the cerebrum of four familial dogs that died of status epilepticus (SE). High values for extracellular levels of Glu and aspartate (ASP) were detected in association with an increased number of spikes and sharp waves during hyperventilation in 3 of 4 the familial epileptic dogs. The values of other amino acids analyzed were not altered in any of the familial epileptic dogs. Immunohistochemically, Glu-positive granules were occasionally found in the perineuronal spaces of the cerebral cortex in 3 of the familial epileptic dogs that died of SE. Immunostains for GLT-1 antibody predominantly decreased in the cerebral cortex and lateral nucleus of the thalamus in all the dogs that died of SE, whereas there were no differences detected in immunolabellings for GLAST and GS antibodies between familial epileptic dogs and controls. These results suggest that an extracellular release of both Glu and Asp may play an important role in the occurrence of seizure activity in this epileptic colony, and that a decreased expression of astrocytic GLT-1 may be related to development of SE.  相似文献   
34.
Canine cutaneous histiocytoma is a common tumor of young dogs. Nodules are single or multiple, alopecic and well demarcated. We studied 15 young dogs with cutaneous histiocytoma. Cutaneous nodules were cytologically and histologically investigated using routine techniques. The subject for morphometry was the nuclear area of histiocytes. The figures were statistically interpreted (Student's t- test). Cytologically, histiocytes represented the largest population, being large-sized cells. The nucleus:cytoplasm ratio was large with oval or bean-shaped nuclei and a fine arrangement of chromatin. The cytoplasm was discrete and basophilic, or abundant and foamy. Five regressive stages were histologically described. Stage 1 was represented by dermal and hypodermal histiocyte proliferation, covered by an intact, uninfiltrated and atrophic epidermis. Epidermal ulcers and necrotizing foci with neutrophilic, lymphocytic and plasma cell infiltrations occurred in Stages 2, 3 and 4. Stage 5 looked like a chronic dermatitis. In Stage 1, the nuclear area was the smallest (4615 ± 62 pixels) with a small coefficient of variation (14.28%), proving a homogeneous population. Stage 2 histiocytes had a larger and more heterogeneous nuclear area (6116 ± 130 pixels) with a 21.12% coefficient of variation. In Stage 3, the average nuclear area (6431 ± 115 pixels) was larger than that for Stage 2 and had a 19.18% coefficient of variation. There were no significant differences between the nuclear areas of histiocytes from Stages 2 and 3; however, significant differences occurred between Stages 1 and 2, and between Stages 1 and 3.
Funding: Self-funded .  相似文献   
35.
Microdialysis System (MDS) is a novel technique used for investigation of molecule secretion between different cell populations. Local hormonal secretion at follicular wall has been still unclear. This MDS study was used to determine progesterone (P4), androstenedione (A4), estradiol-17beta (E2) and Prostaglandin F2alpha (PGF2alpha) release in mare pre-ovulatory follicles. Follicles larger than 30 mm were isolated from the ovary and follicular fluid aspirated for hormone assay. Follicular fluid collected from small, middle and large follicles were analyzed by EIA. The concentrations of P4 and PGF2alpha were similar among the different sizes of follicles. The release of A4 was observed in middle and large follicles. E2 concentration was observed in middle follicles and was higher in large follicles compared with middle follicles. Follicular wall was cut and incubated for MDS and when LH was infused, there was an increase in P4 and A4 release. PGF2alpha release was considerably high after LH infusion compared to the control group. Infusion of PGF2alpha increased P4 and A4 release but there was no change in E2 release. This results suggest that in pre-ovulatory follicles, LH stimulates theca interna cells and also PGF2alpha seemed to have a mediator role to induce steroid hormone production and luteinization of follicular cells. The nature of the mechanisms involved in selection of large follicles is still a perplexing research problem in reproduction.  相似文献   
36.
The forward and reverse suppression subtractive cDNA libraries were constructed in petals of Eustoma grandiflorum at bud stage (stage 1) and anthesis (stage 7). Approximately 1000 clones were isolated from stage 1- (S1) and stage 7-specific (S7) libraries. The clones were sequenced and assembled, which yielded 98 contigs and 444 singletons. BLAST search was conducted on these assembled sequences. Generally, probes isolated from the S7 library exhibited higher expression at stage 7 by microarray analysis, as did those of the S1 library at stage 1. A clone set from the S7 library contained genes from later steps of anthocyanin biosynthesis pathway, terpene synthases, GAST (gibberellic acid-stimulated) family proteins, xyloglucan endotransglucosylase/hydrolase, glycosidases, and stress- and senescence-related proteins. In contrast, the S1 library contained genes associated with flavonol biosynthesis, phenylpropanoid metabolism, terpenoid metabolism, and floral organ development. Gene expression profiling for flavonoid biosynthesis was in accordance with preferential accumulation of flavonols at bud stages and anthocyanins at anthesis.  相似文献   
37.
The distribution pattern and biomass of the Japanese anchovy Engraulis japonicus in the offshore region of the western North Pacific (north of 35°N and west of 170°E) were studied using a quantitative echosounder. This is the first attempt at such a study in this region. Data were collected in summer from 2004 to 2007. The biomass was estimated using data collected at 38?kHz. Species compositions in the backscatterings from pelagic fish were assigned based on the results of trawl hauls taking account of sea surface temperature (SST). Japanese anchovy tended to be high density to the west of 153°E and were distributed in an SST range of 9?C24?°C. Although the temporal and spatial coverage of the survey differed each year, at least 1.5?C3.4 million tons of Japanese anchovy were present in the survey area between 2004 and 2007. To take account of the spatial coverage of the survey each year, the most reliable biomass estimate for this region in the time period was 3.4 million tons (coefficient of variation?0.22).  相似文献   
38.
39.
To investigate the emotional reactivity of fish in a novel environment, the swimway test was developed. The swimway apparatus consists of a shaded start chamber and an open, illuminated swimway. Fish were first introduced and habituated to the start chamber. A door partitioning the start chamber from the swimway was then opened, and behavioral responses of the fish in the apparatus were measured. By using the swimway test, behavioral responses to a novel environment of bluegill Lepomis macrochirus, crucian carp Carassius langsdorfii, and goldfish Carassius auratus were quantified and compared. The emotional reactivities in blue gill were found to be the lowest and crucian carp the highest, indicating bluegill are relatively active or ‘bold’, and that the crucian carp are relatively passive or ‘shy’, in a novel environment. It is suggested that the swimway test is applicable to examning inter-species differences in relative emotional reactivity or boldness in a simplified novel situation.  相似文献   
40.
Zuiki, a stalk of taro (Colocasia esculenta), is a traditional vegetable in Japan. Raw zuiki is often boiled and vinegared to eat. The surface color of zuiki is reddish. Here, we isolated a red pigment from zuiki and identified it as cyanidin 3-rutinoside using instrumental analyses. The color of zuiki disappeared by boiling, but the zuiki turned red again in an acetic acid solution. It seems that the cyanidin 3-rutinoside that exists on the surface of zuiki elutes in boiling water and then, the pigment that seeps out from the inside of the zuiki is exposed to an acid solution, and its surface turns red again. The radical scavenging activity of purified zuiki anthocyanin was 114 mg equivalent to BHT/g. About half of the anthocyanin in fresh zuiki was washed out by boiling, and the radical scavenging activity of zuiki was definitely reduced.  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