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   119篇
  免费   13篇
  国内免费   1篇
林业   3篇
农学   8篇
基础科学   3篇
  21篇
综合类   12篇
农作物   7篇
水产渔业   32篇
畜牧兽医   30篇
园艺   4篇
植物保护   13篇
  2023年   1篇
  2022年   5篇
  2021年   3篇
  2020年   1篇
  2019年   5篇
  2018年   6篇
  2017年   8篇
  2016年   9篇
  2015年   5篇
  2014年   4篇
  2013年   7篇
  2012年   6篇
  2011年   9篇
  2010年   10篇
  2009年   6篇
  2008年   7篇
  2007年   6篇
  2006年   4篇
  2005年   5篇
  2004年   2篇
  2003年   3篇
  2002年   2篇
  2001年   3篇
  1999年   2篇
  1998年   2篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1992年   5篇
  1984年   2篇
  1973年   1篇
排序方式: 共有133条查询结果,搜索用时 15 毫秒
111.
White leg shrimp, Penaeus vannamei, were collected on a monthly basis from grow‐out ponds located at Tamil Nadu and Andhra Pradesh states along the east coast of India for screening of viral and other pathogens. Totally 240 shrimp samples randomly collected from 92 farms were screened for white spot syndrome virus (WSSV), infectious hypodermal and haematopoietic necrosis virus (IHHNV), infectious myonecrosis virus (IMNV) and Enterocytozoon hepatopenaei (EHP). The number of shrimp collected from shrimp farms ranged from 6 to 20 based on the body weight of the shrimp. All the shrimp collected from one farm were pooled together for screening for pathogens by PCR assay. Among the samples screened, 28 samples were WSSV‐positive, one positive for IHHNV and 30 samples positive for EHP. Among the positive samples, four samples were found to be positive for both WSSV and EHP, which indicated that the shrimp had multiple infections with WSSV and EHP. This is the first report on the occurrence of multiple infections caused by WSSV and EHP. Multiplex PCR (m‐PCR) protocol was standardized to detect both pathogens simultaneously in single reaction instead of carrying out separate PCR for both pathogens. Using m‐PCR assay, naturally infected shrimp samples collected from field showed two prominent bands of 615 and 510 bp for WSSV and EHP, respectively.  相似文献   
112.
新疆盐渍化区土壤养分的空间结构和分布特征   总被引:2,自引:2,他引:2  
结合地理信息系统(GIS),在面积约为2000km2的新疆典型盐渍化区渭干河流域布设了土壤取样点43个,测定了土壤表层(0~30cm)养分(全氮、全磷、全钾、碱解氮、速效磷、速效钾)的空间变异规律。结果表明:七种养分元素中除了碱解氮、速效磷的含量服从对数正态分布,其它养分元素均符合正态分布;半方差分析得出各项目都能很好的用模型来拟合,全氮、全磷、速效钾符合指数模型,碱解氮、速效磷、全磷符合球状模型。只有有机质是符合高斯模型;全氮和碱解氮的系统空间相关性很弱,而其余养分元素均表现出中等强度的空间相关性,变程在14.3km~67.0km之间,相差比较大;用Kriging插值法对未测点的养分元素进行最优估计,绘制含量分布图,从而可以更直观的反映研究区土壤养分的空间结构和分布特征。  相似文献   
113.
The past few decades have witnessed hundreds of family-based linkage studies mapping for numerous traits but only a limited number of QTLs were actually cloned, tagged, or used for marker-assisted selection. Although providing valuable information, this conventional approach cannot be scaled up to underpin the incredible amount of phenotypic variation in the form of 266, 589 hexaploid wheat accessions maintained in public germplasm collections. Association mapping has recently emerged as an alternative and more powerful mapping approach where a natural population is surveyed to determine marker-trait associations using linkage disequilibrium (LD). After its first application for milling quality in 2006, association mapping studies in hexaploid wheat are being extended to tag yield traits, protein quality, and tolerance to biotic and abiotic stresses. Advances in genotyping technology and statistical approaches greatly accelerated the shift from conventional linkage-based mapping to LD-based association mapping. Association mapping stands out because of simultaneous utilization of a large number of ex situ-conserved natural variation due to historical recombination events accumulated over centuries.  相似文献   
114.
Protein isolates extracted from differently stabilized rice bran were analyzed to work out the food use potential. Bulk density remained higher for isolates obtained from heat stabilized bran, the treatments were found to have positive impact on the oil absorption properties, while the water absorption was slightly impaired owing to some possible configurational changes. Surface hydrophobicity and emulsion properties were improved with bran stabilization. Isolates exhibited better foaming properties owing to the flexible nature of protein molecules, with less intensive disulfide bonding, that were slightly affected by the stabilization treatment. Nitrogen solubility index followed a curved pattern with the least value near isoelectric point that showed an increasing trend toward basic pH, and parboiled protein isolates exhibited better gelling properties among the isolates.  相似文献   
115.

This study aimed to investigate the effect of CIDR, re-used wCIDR, and Ovsynch protocols for the synchronization of follicular waves on ovarian hormones, oxidative stress, and antioxidant biomarkers during the breeding season. Dromedary camels (N?=?18) were divided into three equal groups. The first group received CIDR. The second group received previously used wCIDR after thorough cleaning and disinfection. The third group was subjected to GPG protocol. Progesterone (P4), estradiol (E2) l, total antioxidant capacity (TAC), catalase (CAT), lipid peroxide product (MDA), nitric oxide (NO), and glutathione reduced (GSH) were measured. Days during CIDR affected P4 (P?= 0.0001), E2 (P?= 0.047), TAC (P?= 0.01), NO (P?= 0.028), and GSH (P?= 0.005). Days during re-used wCIDR effected P4, TAC, CAT, NO, GSH, and MDA (P?≤ 0.001). Days during GPG effected P4, E2, TAC, GSH (P?= 0.0001), MDA (P?= 0.036), and NO (P?= 0.02). CIDR-treated camels had high P4 (P?= 0.0001), E2 (P?= 0.0001), TAC (P?= 0.012), and NO (P?= 0.0001), with low GSH (P?= 0.001), and MDA (P?= 0.003). Exogenous progesterone improved ovarian hormones and the antioxidant capacity and minimized the oxidative stress than the GPG treatment and is recommended for future reproductive management of camels.

  相似文献   
116.
To demonstrate the expression of heat shock proteins (Hsps) in the kidney, 5 kinds of Hsps, namely, Hsp70, Hsp72, Hsp86, Hsp90, and Hsp27, were examined in pigs after 6-h-transports by using western blot analysis. All 5 Hsps were detected in the kidneys of both the transported and control pigs. Hsp expression in the control pigs indicated that Hsps have some physiological functions in addition to stress-response functions. With the exception of Hsp27, a significant reduction was observed in all the levels of Hsps in the kidneys of the transport-stressed pigs after 6 h of transport, particularly in the levels of Hsp70 and Hsp72, which belong to the HSP70 family; and Hsp86 and Hsp90, which belong to the HSP90 family. The results indicate that 6-h-transports are not only related to renal pathological injury but also to a reduction in most of Hsp levels in the kidney. However, slight Hsp27 induction (< 0.05) indicates that Hsps that undergo different changes following transportation stress are involved in different physiological functions. Whether the decreased amount of a certain Hsp may indicate damage and/or overuse and whether Hsps actually protect kidney tissue from such overuse remain to be elucidated.  相似文献   
117.
Maize plant has an absolute requirement of nutrients (N, P, and K) for growth and development. The microbial application can facilitate in addressing limited access to chemical fertilizer concern. Moreover, biochar and phosphorus-solubilizing bacterial (PSB) community can contribute together in nutrient availability. Both have the P-supply potential to the soil, but their interaction has been tested less under semiarid climatic conditions. The purpose of the study was to evaluate the potential of biochemically tested promising PSB strains and biochar for maize plant growth and nutritional status in plant and soil. Therefore, two isolated PSB strains from maize rhizosphere were biochemically tested in vitro and identified by 16S rDNA gene analysis. The experiment was conducted in the greenhouse where the plant growth and nutrient availability to the plants were observed. In this regard, all the treatments such as PSB strain-inoculated plants, biochar-treated plants, and a combination of PSBs + biochar-treated plants were destructively sampled on day 45 (D45) and day 65 (D65) of sowing with four replications at each time. PSB inoculation, biochar incorporation, and their combinations have positive effects on maize plant height and nutrient concentration on D45 and D65. In particular, plants treated with sawdust biochar + Lysinibacillus fusiformis strain 31MZR inoculation increased N (32.8%), P (72.5%), and K (42.1%) against control on D65. Besides that, only L. fusiformis strain 31MZR inoculation enhanced N (23.1%) and P (61.5%) than control which shows the significant interaction of PSB and biochar in nutrient uptake. PSB and biochar have the potential to be used as a promising amendment in improving plant growth and nutrient absorption besides the conventional approaches.  相似文献   
118.
运输应激猪肝脏中热应激蛋白的定位与表达   总被引:1,自引:0,他引:1  
 利用免疫组织化学定位方法和Westernblot技术 ,对长途运输试验猪肝脏中 5种不同分子量的热应激蛋白HSP70 、HSP72 、HSP86、HSP90 和HSP2 7进行定位和表达。所有长途运输后应激猪和对照猪肝脏组织中均同时检测到了上述 5种HSP。肝细胞胞浆和胞核均显示阳性信号 ,但HSPs在肝细胞中的定位有差异 ,大多数HSP70 、HSP72 和HSP2 7主要分布于肝细胞胞浆内 ,而HSP90 和HSP86阳性颗粒在核内的分布比其在胞浆中的分布更为明显。肝小叶周边区有明显颗粒变性和脂肪变性的肝细胞中HSPs的阳性染色信号较弱。 6h的长途运输应激后 ,与对照组相比 ,HSPs在肝脏组织中的表达量存在差异 ,表现为HSP70 家族的HSP70 和HSP72 的表达没有明显的升高 (P >0 .0 5 ) ,HSP90 家族的HSP90 的表达出现极显著的增加 (P <0 .0 1) ,然而 ,HSP90 家族的HSP86和小分子量家族的HSP2 7的表达量呈现明显的下降 (P <0 .0 5 )。  相似文献   
119.
The present study was conducted to isolate and characterize rhizobial strains from root nodules of cultivated legumes, i.e. chickpea, mungbean, pea and siratro. Preliminary characterization of these isolates was done on the basis of plant infectivity test, acetylene reduction assay, C-source utilization, phosphate solubilization, phytohormones and polysaccharide production. The plant infectivity test and acetylene reduction assay showed effective root nodule formation by all the isolates on their respective hosts, except for chickpea isolate Ca-18 that failed to infect its original host. All strains showed homology to a typical Rhizobium strain on the basis of growth pattern, C-source utilization and polysaccharide production. The strain Ca-18 was characterized by its phosphate solubilization and indole acetic acid (IAA) production. The genetic relationship of the six rhizobial strains was carried out by random amplified polymorphic DNA (RAPD) including a reference strain of Bradyrhizobium japonicum TAL-102. Analysis conducted with 60 primers discriminated between the strains of Rhizobium and Bradyrhizobium in two different clusters. One of the primers, OPB-5, yielded a unique RAPD pattern for the six strains and well discriminated the non-nodulating chickpea isolate Ca-18 from all the other nodulating rhizobial strains. Isolate Ca-18 showed the least homology of 15% and 18% with Rhizobium and Bradyrhizobium, respectively, and was probably not a (Brady)rhizobium strain. Partial 16S rRNA gene sequence analysis for MN-S, TAL-102 and Ca-18 strains showed 97% homology between MN-S and TAL-102 strains, supporting the view that they were strains of B. japonicum species. The non-infective isolate Ca-18 was 67% different from the other two strains and probably was an Agrobacterium strain.  相似文献   
120.
Impact of yield and quality-related traits of sugarcane on sugar recovery   总被引:1,自引:0,他引:1  
Sugar recovery of Pakistani sugarcane varieties is relatively low as compared to the rest of the world while very little work is done on this aspect. The current study was conducted to tackle this issue and to assess the effect of quality and yielding traits on final sugar recovery. Sixty genotypes of sugarcane were sown during 2013 and data was collected at different growth stages during maturity and post maturity. Correlation studies indicated that polarity (0.77**) and purity (0.73**) were positively and significantly correlated with sugar recovery while brix% (-0.21**), fiber contents (-0.21**) and number of leaves per plant (-0.33**) were significant and negatively correlated with sugar recovery. Furthermore, leaf area was positively and significantly correlated with internode length (0.63**). Path coefficient analysis indicated that highest direct effect on sugar recovery was shown by purity (2.92), followed by brix% (2.48), and leaf area (0.66) which confirms that these traits could contribute more towards an increase of sugar recovery. Overall values of higher direct and indirect effects were observed by purity. The results of the current studies indicate that sugar recovery can be improved by focusing on purity, brix%, and leaf area.  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