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   201篇
  免费   4篇
林业   12篇
农学   8篇
  20篇
综合类   9篇
农作物   3篇
水产渔业   15篇
畜牧兽医   119篇
园艺   3篇
植物保护   16篇
  2022年   5篇
  2021年   11篇
  2019年   2篇
  2018年   1篇
  2017年   1篇
  2016年   3篇
  2015年   16篇
  2014年   12篇
  2013年   15篇
  2012年   12篇
  2011年   17篇
  2010年   5篇
  2009年   9篇
  2008年   15篇
  2007年   10篇
  2006年   8篇
  2005年   11篇
  2004年   17篇
  2003年   5篇
  2002年   9篇
  2001年   3篇
  2000年   3篇
  1998年   3篇
  1997年   1篇
  1993年   1篇
  1992年   2篇
  1991年   1篇
  1988年   1篇
  1985年   1篇
  1984年   1篇
  1980年   1篇
  1979年   1篇
  1975年   1篇
  1974年   1篇
排序方式: 共有205条查询结果,搜索用时 78 毫秒
111.
112.
The radish (Raphanus sativus) is a root vegetable of the Brassicaceae family which shows amylolytic activity in the taproot. However, there is little information about differences in these amylolytic activities among radish cultivars. We analyzed the amylase activities and starch contents of 7 kinds of radish cultivars. The Koshin cultivar showed the highest amylase activity, with a level approximately 6 times higher than that of the Sobutori cultivar, which had the lowest. Cultivars with higher amylase activities showed higher starch contents. These results suggest that there are intraspecies variations in amylolytic activities in radishes, and positive correlations between amylase activity and starch content.  相似文献   
113.
114.
Juvenile red king crabs (RKCs) Paralithodes camtschaticus have a strong tendency for cannibalism, which is an obstacle for seedling production. We investigated the effects of density-dependent cannibalism on the survival rate and on growth, and estimated the optimal stocking density. Four different stocking densities of juvenile first instar crabs were maintained in tanks (50, 100, 200 and 400 individuals per 100-l tank: bottom area was 0.25 m2) during the 209 or 216 days of rearing. The survival rate was affected by stocking density, elapsed days, and the interaction between these variables. Although carapace length, an index of body size, was also affected by density, elapsed days, and the interaction between these variables, the effect associated with density was quite small, suggesting that cannibalism did not intensely affect growth of juvenile crabs. We then estimated the initial stocking density that maximizes the number of survivors using parameters of analyses. Optimal initial stocking density was predicted as 416, 197 and 149 individuals per tank when the target size was assumed as 5.0, 10.0 and 15.0 mm, respectively. This estimation provides a baseline for seedling production in RKCs and could be further improved by considering other factors that affect survival and growth of RKCs.  相似文献   
115.
The purpose of this observational study was to determine the characteristic computed tomographic (CT) myelography findings of cervical vertebral stenotic myelopathy (CVSM) lesions in Thoroughbred horses. A total of 23 Thoroughbred horses (age range, 155–717 days on CT examination; mean, 410.9 days) were analyzed. All 23 Thoroughbred horses underwent unenhanced radiography, radiographic myelography, and CT myelography. Unenhanced radiographs were observed the presence of cervical vertebral malalignment and osseous lesions. Radiographic myelograms were observed for signs of cervical spinal cord compression; additionally, CT myelograms were used to detect cervical vertebral osseous lesions. Ventral compressions were frequently observed in the cranial cervical vertebrae (C2–C4), whereas dorsal compressions were frequently observed in the caudal cervical vertebrae (C5–C7). Furthermore, osseous lesions of the caudal articular process developed more frequently than those of the cranial articular process. CT myelography in Thoroughbred horses is a useful method for detecting CVSM changes.  相似文献   
116.
Neonicotinoid pesticides (NNs) cause behavioral abnormalities in mammals, raising concerns about their effects on neural circuit activity. We herein examined the neurological effects of the NN clothianidin (CLO) by in vivo Ca2+ imaging using two-photon microscopy. Mice were fed the no-observed-adverse-effect-level (NOAEL) dose of CLO for 2 weeks and their neuronal activity in the primary somatosensory cortex (S1) was observed weekly for 2 weeks. CLO exposure caused a sustained influx of Ca2+ in neurons in the S1 2/3 layers, indicating hyperactivation of neurons. In addition, microarray gene expression analysis suggested the induction of neuroinflammation and changes in synaptic activity. These results demonstrate that exposure to the NOAEL dose of CLO can overactivate neurons and disrupt neuronal homeostasis.  相似文献   
117.
From 2012 to 2017, serial ultrasonographic evaluation of 5 healthy bottlenose dolphins, Tursiops truncatus, were performed over the course of 6 pregnancies in Enoshima Aquarium. A total of 98 ultrasonographic examinations were included in the study. In three out of six cases, two embryos were observed between umbilicus and genital slit, and side of umbilicus in the dam’s body. All embryos were located in right below the peritoneum and observed from 308 to 325 days pre-partum. These days were corresponding to from 58 to 61 days after copulation respectively. The diameter of the embryo sac was approximately 4 cm. In three cases, the fetal head was located in the dam’s left lateral between umbilicus and genital slit from approximately 90 days pre-partum to the parturition. A snout of fetus is at the top of the uterine horn, and the tail lies close to the cervix. All six calves were fluke-first births (breech presentation). It was conjectured that the contraction of the dam’s uterus during parturition forced the fetus to invert, and the fetal tail fluke was expelled from the dam’s body. In three cases, judging from orientation of fetal tail fluke faced towards left side of the dam, a fetal position might be RSL (Right Sacrum-Lateral) within the birth canal. In the other three cases, the left and right positions of the fetus and the dam’s body are reversed during pregnancy and parturition.  相似文献   
118.
Water soluble phosphoric acid in ordinary superphosphate and double (or triple) superphosphate consists of mainly monocalcium phosphate, but it also contains one to several per cent free phosphoric acid. Both free acid and water are the essential components in order to know the change in curing or to estimate the reduction of posphoric acid in manufacture of mixed fertilizer.  相似文献   
119.
Oolong tea theasinensins are a group of tea polyphenols different from green tea catechins and black tea theaflavins. The present study reports the inhibitory effects of oolong tea theasinensins on the expression of cyclooxygenase-2 (COX-2) and underlying molecular mechanisms in lipopolysaccharide (LPS)-activated murine macrophage RAW264 cells. The structure-activity data revealed that the galloyl moiety of theasinensins played an important role in the inhibitory actions. Theasinensin A, a more potent inhibitor, caused a dose-dependent inhibition of mRNA, protein, and promoter activity of COX-2. An electrophoretic mobility shift assay (EMSA) revealed that theasinensin A reduced the complex of NF-κB- and AP-1-DNA in the promoter of COX-2. Signaling analysis demonstrated that theasinensin A attenuated IκB-α degradation, nuclear p65 accumulation, and c-Jun phosphorylation. Furthermore, theasinensin A suppressed the phosphorylation of MAPKs, IκB kinase α/β (IKKα/β), and TGF-β activated kinase (TAK1). These data demonstrated that the down-regulation of TAK1-mediated MAPKs and NF-κB signaling pathways might be involved in the inhibition of COX-2 expression by theasinensin A. These findings provide the first molecular basis for the anti-inflammatory properties of oolong tea theasinensins.  相似文献   
120.
The complete genome sequences of two Brazilian wild-type rabies viruses (RABV), a BR-DR1 isolate from a haematophagous bat (Desmodus rotundus) and a BR-AL1 isolate from a frugivorous bat (Artibeus lituratus), were determined. The genomes of the BR-DR1 and BR-AL1 had 11,923 and 11,922 nt, respectively, and both encoded the five standard genes of rhabdoviruses. The complete nucleotide sequence identity between the BR-DR1 and BR-AL1 isolates was 97%. The BR-DR1 and BR-AL1 isolates had some conserved functional sites revealed by the fixed isolates, whereas both isolates had unique amino acid substitutions in the antigenic region IV of the nucleocapsid gene. Therefore, it is speculated that both isolates were nearly identical in virologic character. According to our phylogenetic analysis based on the complete genomes, both isolates belonged to genotype 1, and to the previously defined "vampire bat-related RABV lineage" which consisted of mainly D. rotundus- and A. lituratus-isolates; however, a branch pattern with high bootstrap values suggested that BR-DR1 was more closely related to the 9001FRA isolate, which was collected from a dog bitten by a bat in French Guiana, than to BR-AL1. This result suggests that the vampire bat-related RABV lineage includes Brazilian vampire bat and Brazilian frugivorous bat RABV and is further divided into Brazilian vampire bat and Brazilian frugivorous bat RABV sub-lineages. The phylogenetic analysis based on the complete genomes was valuable in discriminating among very closely related isolates.  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