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   370篇
  免费   27篇
林业   37篇
农学   29篇
  63篇
综合类   12篇
农作物   17篇
水产渔业   76篇
畜牧兽医   99篇
园艺   10篇
植物保护   54篇
  2024年   1篇
  2023年   6篇
  2022年   11篇
  2021年   24篇
  2020年   19篇
  2019年   28篇
  2018年   20篇
  2017年   20篇
  2016年   19篇
  2015年   14篇
  2014年   18篇
  2013年   18篇
  2012年   21篇
  2011年   28篇
  2010年   18篇
  2009年   15篇
  2008年   27篇
  2007年   19篇
  2006年   12篇
  2005年   14篇
  2004年   12篇
  2003年   7篇
  2002年   7篇
  2001年   4篇
  2000年   3篇
  1999年   4篇
  1998年   2篇
  1996年   1篇
  1994年   2篇
  1987年   1篇
  1984年   1篇
  1983年   1篇
排序方式: 共有397条查询结果,搜索用时 15 毫秒
291.
Leishmune vaccination covers a broader number of endemic areas of canine visceral leishmaniasis (CVL) and therefore the development of new serological devices able to discriminate CVL from Leishmune vaccinees becomes an urgent need considering the post-vaccine seroconversion detected throughout conventional methodologies. Herein, we have described the establishment of a flow cytometry based methodology to detect anti-fixed L. (L.) chagasi promastigotes antibodies (FC-AFPA-IgG, FC-AFPA-IgG1 and FC-AFPA-IgG2) in sera samples from Leishmania (Leishmania) chagasi infected dogs and Leishmune vaccinees. The results of FC-AFPA were reported along the sera titration curve (1:128-1:524,288), as percentage-of-positive-fluorescent-parasite (PPFP). The use of PPFP=20% as a cut-off edge to segregate negative and positive results at sera dilution 1:2048 revealed outstanding performance indexes that elect FC-AFPA-IgG and IgG2 (both detected by polyclonal FITC-labeled second step reagent) applicable to the serological diagnosis of CVL, with 100% of specificity for both IgG and IgG2 and 97 and 93% of sensitivity, respectively. Moreover, FC-AFPA-IgG, applied at sera dilution 1:2048, also appeared as a useful tool to discriminate L. chagasi infected dogs from Leishmune vaccinees, with 76% of specificity. Outstanding likelihood indexes further support the performance of FC-AFPA-IgG for exclusion diagnosis of CVL in Leishmune vaccinees. Analysis of FC-AFPA-IgG at sera dilution 1:8192 revealed the most outstanding indexes, demonstrating that besides the ability of PPFP 相似文献   
292.
A 2‐year‐old neutered male European short‐haired cat was presented for a persistent discharge from the scar of previous left eye enucleation, performed 6 months prior by the referring veterinarian. A surgical exploration of the orbit was performed and retained nictitating membrane glandular and conjunctival tissues were removed. Eleven days later, the cat developed an orbital pneumatosis caused by retrograde movement of air through a patent nasolacrimal system and diagnosed by survey radiographic examination of the skull. Nasolacrimal system patency was assessed by dacryocystography performed by injection of iodinated contrast medium under pressure into the orbital cavity. Computed tomography dacryocystography confirmed the radiographic findings. The condition resolved following dacryocystography, possibly as an inflammatory response to the contrast medium. To our knowledge, this is the first case of orbital pneumatosis reported in a cat.  相似文献   
293.
The genetic control of tree ring growth in Douglas-fir in response to the drought and heat-wave that occurred in 2003 in Europe was studied with microdensity profiles in three clonal experiments located in three different French regions. The drought and heat-wave significantly affected Douglas-fir wood formation. The Chassenoix site (Northeast of Massif-Central) was more severely affected that the other two: the 2003 year-ring was narrower and less dense than in the other sites and than the previous (2002) and following (2004) year-rings in the same site: ring growth stopped earlier and latewood did not develop completely. The year-rings 2004 and 2002 were very similar in this site. There was a significant genetic control for all ring parameters in the three sites and during the three years. The heritability was highly variable between years and among sites, without any clear pattern in this variability, except in Chassenoix where it was slightly lower in the 2003 year-ring. Variables measuring the response of trees to the 2003 event, i.e., the difference in ring width between 2002 and 2003, or between 2003 and 2004, showed a very variable degree of genetic control, from very low to relatively high. Douglas-fir seemed plastic enough to acclimate to the drought and heat-wave and then to recover during 2004. Furthermore the level of heritability estimated demonstrates that Douglas-fir has an adaptive potential that could be useful for multi-generation long-term response.  相似文献   
294.
Sportfishing is a growing segment in the fishing sector, which requires the supply of marine shrimps to meet the demand for live baits; however, the extraction of white shrimp from their natural habitat results in overfishing depleting natural stocks. Intensive cultivation in water recirculation system is a worldwide trend for shrimp farming, which, in addition to increasing productivity, minimizes the impact of effluent emission on the environment, reinforcing sustainability. This study analyzed the economic viability of establishing farms for the cultivation of white shrimp (Litopenaeus schmitti) in water recirculation system to meet the market demand of sportfishing for live baits. The indicators were used: internal rate of return (IRR), net present value (NPV) and payback period (PP). The best scenario, with 90 % survival rate and unitary selling prices of US$ 0.50, showed IRR 11.74 %, NPV (10 %) US$ 1,241.88 and PP 5.71 years, demonstrating financial risk for the production of live baits in the conditions proposed in this study.  相似文献   
295.
296.
This study examined the effects of Bacillus licheniformis strain CIGBC‐232, isolated from the gut of shrimp Litopenaeus vannamei and having antagonistic activity against Vibrio harveyi, on the immunity and larval quality of L. vannamei at various ontogenetic stages, in two separate experiments: (1) PL2 to PL17 exposed to the strain CIGBC‐232 under laboratory conditions (2) zoea I to PL8 exposed to the strain CIGBC‐232 and EPICIN 3W probiotics under farming conditions. The first experiment showed that phenoloxidase, peroxidase and superoxide dismutase activities were improved in animals grown with CIGBC‐232 compared to the untreated control. In tests, the resistance to osmotic stress was also enhanced. During the second experiment, animals treated with CIGBC‐232 exhibited significant (< 0.05) increases in phenoloxidase activity (30–40% higher in zoea I–II, mysis II–III and PL 2–7) and in the respiratory burst (30% higher from PL 2 to 7) as compared to those animals that received EPICIN 3W. There was no significant difference in the lectins and agglutinins (except in PL1, 6 and 7), in peroxidase and superoxide dismutase activities, in the resistance to osmotic stress, nor in the survival rate among treatments. CIGBC‐232 treatment was able to reduce, the level of presumptive Vibrio spp. with respect to EPICIN 3W treatment in the tank water as well as in animals. At the end of both experiments, the growth of shrimp, i.e. weight and length was increased by CIGBC‐232 treatment. This study showed the probiotic effect of CIGBC‐232, which appeared to have a better probiotic performance than EPICIN 3W treatment.  相似文献   
297.
298.
299.
300.
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