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   80篇
  免费   2篇
林业   6篇
农学   2篇
  7篇
综合类   26篇
农作物   1篇
畜牧兽医   33篇
园艺   4篇
植物保护   3篇
  2022年   1篇
  2021年   1篇
  2020年   2篇
  2019年   3篇
  2018年   1篇
  2017年   3篇
  2016年   3篇
  2015年   4篇
  2014年   6篇
  2013年   7篇
  2012年   1篇
  2011年   7篇
  2010年   7篇
  2009年   7篇
  2008年   3篇
  2007年   3篇
  2006年   11篇
  2005年   4篇
  2004年   3篇
  2003年   1篇
  1999年   1篇
  1998年   1篇
  1993年   2篇
排序方式: 共有82条查询结果,搜索用时 15 毫秒
1.
Polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and dibenzofurans, HCBs and p, p'-DDE were determined in soil and sediment samples from selected sites in Czecho-Slovakia. for the first three groups of chemicals soil pollution in Czecho-Slovakia is very high. in general, The pollution is higher in the Elbe than in the Danube catchment sediments.  相似文献   
2.
沈虹 《广东园林》2006,28(6):58-61
概述广州市近年园林绿化发展的主要成绩,分析了当前存在的主要问题。提出要树立城市大园林的全局观念,应通过建立健全标准规范,加强科研与信息、资金投入等多种途径,进一步提高广州园林建设的发展水平。  相似文献   
3.
孙学浩  孙惠合 《安徽农业科学》2009,37(24):11649-11650
秋冬连旱是影响宿州冬小麦、油菜等越冬作物生长发育的重要因素。以Z指数≤一0.8为标准,确定宿州市秋冬持续重旱年份序列,建立GM(1,1)预测模型,并应用BP人工神经网络(BP—ANN)对残差进行拟合,对GM(1,1)预测模型进行修正。结果表明,拟合结果较单一的GM(1,1)模型有一定提高。预测2008年后的下一个宿州市秋冬(10月-2月)持续重旱年度发生在2017~2018年,对当地农业生产和防灾减灾有一定的参考价值。  相似文献   
4.
应用LSTAR模型对我国通货膨胀率的动态特征进行的实证研究结果表明:我国通货膨胀率自身调整有明显的非线性特征,分为显著的低通货膨胀区制和高通货膨胀区制,区制转移的平滑参数较大,转移变量为滞后1期通货膨胀率,转折点为0.01036。同时,我国通货膨胀率存在一定程度的非对称性调整,随冲击大小、方向、区制不同而表现不同。此外,我国通货膨胀率具有较高的持久性,高通货膨胀区制的持久性明显低于低通货膨胀区制。  相似文献   
5.
Cytopathogenic and non-cytopathogenic bovine viral diarrhea viruses (BVDVs) were isolated from cattle with mucosal disease or persistent infection in Japan. These isolates were compared for antigenic properties by cross-neutralization tests with Japanese reference strains of BVDV belonging to classical type 1. Significantly low cross-reactivity to reference strains was noted, indicating the viruses to possibly represent a new serotype in Japan. Thus, to determine the genotype of the isolates, nucleotide sequences of the 5′ untranslated region were determined and compared with those of previously reported BVDV 1 and 2. The isolates were clearly shown to belong to BVDV 2, not to BVDV 1.  相似文献   
6.
This case report describes the occurrence of persistent penile erection in a breeding stallion that occurred while the horse was under inhalant anesthesia for a carpal arthroscopy. The horse had no history of breeding problems, and no abnormalities were detected on physical examination, complete blood count, or serum chemistry tests performed prior to surgery. Anesthesia was induced with guaifenesin and ketamine after sedation with xylazine and was maintained with isoflurane in 100% oxygen. Penile erection developed approximately 35 minutes after induction and persisted for over 2 hours despite various physical and pharmacological attempts to alleviate it (massage, cold compresses, intravenous benztropine administration, and intracavernosal phenylephrine). Successful resolution of the erection was obtained by cannulation and drainage of blood from the corpus cavernosum and subsequent irrigation with heparinized sterile saline and infusion of phenylephrine in the corpus cavernosum. The detumescent penis was placed back into the sheath, and purse string sutures were placed in the sheath to ensure the penis would remain inside the sheath during recovery. The stallion's recovery from anesthesia was uneventful, the sutures were removed, and the horse was fitted with a penile sling to prevent additional edema or trauma. The stallion recovered completely from the persistent penile erection. Semen was collected 6 days after the event, and he returned to normal pasture breeding 6 weeks after surgery.  相似文献   
7.
Difficulty was encountered with the insertion of a right atrial pacing lead via the left jugular vein during lead and pacemaker implantation in a clinically normal goat as part of an ongoing rapid atrial pacing – induced atrial fibrillation research project. Fluoroscopic visualization of an abnormal lead advancement path prompted angiographic assessment which revealed a persistent left cranial vena cava (PLCVC) and prominent coronary sinus communicating with the right atrium. Angiography facilitated successful advancement and securing of the pacing lead into the right side of the interatrial septum. Cardiac magnetic resonance imaging/magnetic resonance angiography (MRI/MRA) allowed further characterization of this rare venous anomaly. Even though PLCVC has been reported once in a goat, to the authors' knowledge this is the first report to include MRI/MRA characterization of PLCVC and prominent coronary sinus with successful cardiac pacemaker implantation using the PLCVC.  相似文献   
8.
田泽芸  李丽平  胡振菊 《安徽农业科学》2014,(31):11028-11032,11107
利用NCEP/NCAR再分析资料,通过对2012年7月中旬我国中东部地区持续性强降水过程中东亚夏季风系统中主要成员的时空变化特征进行分析.结果表明,此次持续性强降水期间,副高北界、南亚高压脊线及中纬度锋区位置相对稳定,长江中下游地区一直处于南亚高压反气旋环流东侧偏北风与西风槽前偏南风之间的风向开口辐散区中;副高南撤时,强降水主要位于584 dagpm线北侧,副高北抬时,强降水主要位于584 dagpm线南侧;此次持续性强降水发生前期,大气为上干下湿不稳定层结,当西风带低槽频频携带冷空气南下影响,同时低空西南急流反复加强,其出口区左侧较强的风速梯度为暴雨的发生发展提供了动力条件;低层干空气的不断侵入,低槽和低涡间的垂直正反环流促使垂直上升运动维持或发展,进而造成持续性强降水;高空西风急流加强(减弱)超前低空西南急流加强(减弱)2~5 d,对持续性强降水有超前指示意义.  相似文献   
9.
介绍了持久性有机污染物的定义、特性及其危害,分析了典型持久性有机污染物在中国土壤、水体、大气、农产品等介质中的污染状况,阐述了对被持久性有机污染物污染的介质进行生物修复、焚烧、物理和化学处理技术及进展,并对中国在此领域发展方向进行了展望。  相似文献   
10.
口蹄疫流行病学及感染机制的研究进展   总被引:1,自引:0,他引:1  
杨素娟 《北京农业》2007,(12):43-49
口蹄疫(Foot-and-mouth disease FMD)是由口蹄疫病毒(Foot-and-mouth disease virus FMDV)引起偶蹄动物的一种急性、热性、高度接触性传染病。FMDV有多种血清型及其亚型,目前主要引起动物致病的就有7种,即A、O、C、SATⅠ、SATⅡ、SATⅢ和亚洲Ⅰ型(AsiaⅠ型)。病毒通常在细胞受体的参与下才入侵宿主细胞,进行扩增生命循环,感染宿主细胞,使得该病得以广泛流行。但由于口蹄疫病毒的高度变异性和适应性而在流行中出现新的特点,以及被发现的病毒在动物体内和细胞中长期存在而引发FMDV的持续感染等问题,使得本病不能有效被控制而在许多国家和地区重新暴发和流行。为此本文将口蹄疫病原学、流行病学、病毒细胞受体及其病毒在体内持续感染形成的原因方面进行的论述,为口蹄疫病毒感染机制的研究提供了科学的依据。  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