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   559篇
  免费   26篇
  国内免费   1篇
林业   16篇
农学   27篇
基础科学   1篇
  73篇
综合类   40篇
农作物   63篇
水产渔业   38篇
畜牧兽医   304篇
园艺   6篇
植物保护   18篇
  2024年   1篇
  2023年   3篇
  2022年   4篇
  2021年   10篇
  2020年   13篇
  2019年   10篇
  2018年   13篇
  2017年   15篇
  2016年   10篇
  2015年   25篇
  2014年   26篇
  2013年   38篇
  2012年   35篇
  2011年   67篇
  2010年   33篇
  2009年   22篇
  2008年   47篇
  2007年   25篇
  2006年   35篇
  2005年   26篇
  2004年   20篇
  2003年   28篇
  2002年   23篇
  2001年   16篇
  2000年   15篇
  1999年   7篇
  1996年   1篇
  1994年   2篇
  1993年   5篇
  1992年   3篇
  1990年   1篇
  1989年   3篇
  1983年   2篇
  1977年   1篇
  1967年   1篇
排序方式: 共有586条查询结果,搜索用时 109 毫秒
151.
The random amplified polymorphic DNA (RAPD) and self-incompatibility (SI) typing techniques were applied to settle a lawsuit between a Seed Company and a farmer concerning seed impurity in radish (Raphanus sativus L.). After sowing “Halra Woldong” (HW) a winter radish variety, two morphologically different radish plants grew. Genomic DNA from each of the two types were prepared and analyzed using ninety-six RAPD markers and four variety-specific markers were found. The polymorphic RAPD band patterns were compared with those of the twenty Korean radish varieties. The genetic integrity of the two varieties in question was identified and further confirmed by SI-typing of S-locus glycoprotein (SLG) and S-locus receptor kinase (SRK) genes.  相似文献   
152.
We report upon the distribution of galanin-immunoreactive (GAL-IR) cells in the lumbar dorsal root ganglia (DRG) of the rat, and upon the distribution of GAL-IR cells, which also contain calcitonin gene-related peptide (CGRP)-, substance P (SP)- and somatostatin (SOM)-immunoreactivity. Neuropeptide-immunoreactive lumbar DRG cells were 55.8% for CGRP, 12.7% for SP, and 6.5% for GAL in lumbar DRG cells. There was no significant difference between the right and left DRGs (L1-L6) for any neuropeptide-immunoreactive cell (P < 0.01). In terms of size distribution, CGRP-immunoreactive cells were identified below 1500 microm2, and SP-, and GAL-IR cells below 600 microm2. Neuropeptide immunoreactive cells showed various immunoreactivities in the cytoplasm according to each neuropeptide. CGRP and SP immunoreactive cells were colocalized with GAL immunoreactive cells in the serial sections about 83.3 and 60% respectively, but SOM colocalizing with GAL-IR cells were not in evidence. The current results confirm and extend previous results, and show that neuropeptides can coexist in single sensory neurones of the rat DRG. In addition, our results demonstrate that the normal distribution of some neurotransmitters modulating sensory action in Wistar Kyoto rat, make this model more prone to develop neuropathic pain than Sprague-Dawley rat.  相似文献   
153.
Adverse effects of tributyltin (TBT) chloride were investigated on the reproductive system in male adult rats as exposed during puberty. Fifty Sprague-Dawley rats at the age of 35 days were assigned to five different groups: negative control receiving vehicle, methyltestosterone (10 mg/kg B.W.), and TBT chloride treatments (5, 10, and 20 mg/kg B.W.). Animals were treated by oral gavage for ten consecutive days and sacrificed at 5 weeks after final treatment. The treatment of TBT chloride at the high dose of 20 mg/kg B.W. significantly decreased homogenization-resistant testicular sperm counts (p<0.05). The TBT chloride treatment at the doses of 10 and 20 mg/kg B.W. also significantly decreased caudal epididymal sperm counts (p<0.01). Some of motion kinematic parameters (motility, mean angular displacement, lateral head displacement, and dance) of sperms retrieved from vasa deference were significantly decreased in rats treated with the TBT chloride at the dose of 20 mg/kg B.W. (p<0.05). These results provide a further evidence that an exposure to TBT chloride during pubertal period in male rats produces spermatogenic disorders characterized by decreasing testicular and epididymal sperm counts and some motion parameters of sperms in the vasa deference.  相似文献   
154.
The action of estrogen on target organs has been actively studied with the discovery of estrogen receptor (ER) beta. This study was carried out to examine the expression of ERalpha and ERbeta in the uterus and the vagina of immature Sprague-Dawley rats treated with 17-ethinyl estradiol (EE). Twenty days old rats were subcutaneously treated with EE at the doses of 0 (vehicle control), 0.03, 0.3, 1.0, 3.0, and 10.0 microg/kg/day for three consecutive days. The treatment of EE at the doses of 0.3, 1.0, 3.0 and 10.0 microg/kg/day significantly increased the weights of the uterus and vagina of rats (p<0.01) and retained fluid in the uterus of rats. At the high doses of 3.0 and 10.0 microg/kg/day, the treatment of EE caused an increase in the uterine height, hypertrophy, and a decrease in the expression of ERalpha and ERbeta in the uterine luminal and glandular epithelium. The treatment of EE at the doses of 3.0 and 10.0 microg/kg/day also caused cornification and a decrease in the expression of ERalpha and ERbeta in the vaginal epithelium. These results suggest that the EE treatment decrease the expression of ERalpha and ERbeta in the uterus and vagina of immature rats and that may be associated with the morphological changes such as increase in the uterine height, hypertrophy of the uterine epithelium, and cornification of the vagina.  相似文献   
155.
Kichang Lee  DVM  MS    Mincheol Choi  DVM  PhD    Junghee Yoon  DVM  PhD    Juhyun Jung  DVM  MS 《Veterinary radiology & ultrasound》2004,45(2):166-171
Normal values of arterial blood flow velocity and waveforms in major arteries of 10 healthy conscious Beagle dogs were determined using Doppler ultrasonography. Peak systolic, early diastolic, and end-diastolic velocities of the basilar artery, common carotid artery, abdominal aorta, external iliac artery, femoral artery, and peak ejection velocity of the valvular aorta were evaluated. Pulsatility index (PI) of the basilar artery and blood pressure were recorded. All arteries had a high-resistance flow pattern with triphasic flow velocity except the basilar artery, which had a low-resistance pattern. Mean peak systolic velocities of the basilar artery, common carotid artery, abdominal aorta, external iliac artery, and femoral artery were 72 +/- 19, 115 +/- 17, 121 +/- 24, 105 +/- 25, and 110 +/- 17 cm/s, respectively. The PI of the basilar artery and peak ejection velocity of the valvular aorta were 1.37 +/- 0.13 and 96 +/- 16 cm/s, respectively. Mean systolic and diastolic blood pressures were 137 +/- 13 and 78 +/- 15 mmHg, respectively. Present findings may be used as references in future studies on vascular diseases and hemodynamics in dogs.  相似文献   
156.
In this study the subtype of eae gene was determined by polymerase chain reaction for a total of 59 attaching and effacing Escherichia coli isolated from preweaned (38 isolates) and postweaned (21 isolates) pigs. The eae(beta) gene detected in 19 E. coli from preweaned pigs and 10 E. coli from postweaned pigs was found to be the most common subtype, followed by eae(gamma), eae(epsilon), and eae(zeta) genes. Subtypes were not determined for 7 E. coli isolates. No other subtype of the eae gene was detected in eae+ E. coli evaluated in this study.  相似文献   
157.
The expression of calbindin D-28k (CB), calretinin (CR), substance P (SP) and calcitonin gene-related peptide (CGRP) in the stomach myenteric plexus of the Korean native goat stomach was investigated by immunohistochemistry. The results demonstrated the presence of nerve fibers and cell bodies immunoreactive (IR) to CB, CR, SP and CGRP. In tissues of rumen, reticulum, omasum and abomasum, some distinct neuronal populations could be distinguished according to their morphologic and neuronal chemical properties: Dogiel type I cells which have irregular lamellar dendrites and a single axon, Dogiel type II cells which have large ovoid cell bodies and several long axon-like processes, and small filamentous interneurons. CB-, CR-, SP- and CGRP-IR neurons and fibers were observed in the myenteric plexus of stomach, and varicose nerve fiber immunostained to SP and CGRP also were found in the muscle layer. In myenteric plexus of the stomach, CB- and SP-positive neurons were characterized by Dogiel type II and CR-IR neurons were classified Dogiel type I with lamellar dendrites, and immunoreactivity of CGRP was very weak in the somata. SP- and CGRP-IR nerve fibers formed dense networks within the myenteric ganglia. SP-IR cell bodies and their fibers were found in the myenteric plexus, and the immunoreactivity and number of cell bodies were more than CB-, CR-, and CGRP-IR neurons. These results suggest that SP, CGRP, CB and CR in the myenteric neurons of Korean native goat stomach may have play an important role in the dynamic movement.
(Support contributed by: Korean Research Foundation 2003-015-E00195).  相似文献   
158.
This study is designed to demonstrate the distribution of nociceptin, endogenous ORL1 receptor ligand, in the central nervous system of the Mongolian gerbil. To intensify the nociceptin-like immunoreactivity (NOC-LI), colchicine was administered into the lateral ventricle, at 48 h prior to the transcardiac perfusion. In the group without colchicine treatment, NOC-LI was observed in the fibres of the spinal dorsal horn, specifically in the superficial layers. However, the NOC-LI in the superficial layers disappeared after the administration of colchicine. In the brain, NOC-LI was prominent in the hypothalamus, hippocampus, cerebral peduncle, substantia nigra, dorsal raphe, periaqueductal grey, locus coeruleus and trapezoid nucleus. Colchicine treatment markedly intensified the NOC-LI in the somata of the central nervous system, whereas the untreated sections were too weak to observe and analyse. The distribution of NOC-LI provides informative data for studies of the neuronal circuit that nociceptin may be involved in.  相似文献   
159.
<正>由产生肠毒素的大肠杆菌(Escherichia coli)所引起的腹泻是威胁家畜健康和存活的主要因素之一,尤其是对于仔猪和犊牛(Nagy等,2005;Fairbrother等,  相似文献   
160.
Spontaneously hypertensive rats (SHRs) are widely accepted in medical research because this model has been used for studies in neurodegenerative diseases such as vascular dementia and stroke. In the present study, we observed newly generated neuronal precursors using doublecortin (DCX, a marker of neural proliferation and differentiation) in the subgranular zone of the dentate gyrus in SHRs compared to Sprague-Dawley rats (SDRs) at various age stages. DCX immunoreactivity, immunoreactive cell numbers and its protein level in the dentate gyrus of the SHRs were higher than those in the SDRs at postnatal month 1 (PM 1). At PM 8, DCX immunoreactivity, immunoreactive cell numbers and protein levels in both groups were markedly decreased compared to those at PM 1; however, they were higher than those in the SDRs. They were decreased in the both groups with age: DCX immunoreactive cells in the SDRs were few at PM 12. Our results indicate that newly generated neuronal precursors are more abundant in SHRs than in SDRs during their life.  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