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   229篇
  免费   6篇
林业   22篇
农学   11篇
基础科学   4篇
  49篇
综合类   17篇
农作物   20篇
水产渔业   30篇
畜牧兽医   50篇
园艺   5篇
植物保护   27篇
  2024年   1篇
  2023年   3篇
  2022年   6篇
  2021年   9篇
  2020年   6篇
  2019年   16篇
  2018年   7篇
  2017年   8篇
  2016年   5篇
  2015年   5篇
  2014年   10篇
  2013年   13篇
  2012年   11篇
  2011年   16篇
  2010年   13篇
  2009年   12篇
  2008年   14篇
  2007年   4篇
  2006年   5篇
  2005年   3篇
  2004年   6篇
  2003年   3篇
  2002年   6篇
  2001年   8篇
  2000年   3篇
  1999年   6篇
  1998年   3篇
  1997年   1篇
  1996年   2篇
  1992年   1篇
  1988年   4篇
  1987年   1篇
  1986年   3篇
  1985年   2篇
  1984年   1篇
  1983年   1篇
  1981年   1篇
  1980年   1篇
  1979年   3篇
  1977年   1篇
  1975年   1篇
  1974年   1篇
  1971年   1篇
  1969年   4篇
  1968年   1篇
  1967年   3篇
排序方式: 共有235条查询结果,搜索用时 359 毫秒
61.
The aryloxyphenoxypropionic acid (AOPP) and cyclohexanedione (CHD) herbicides inhibit the first committed enzyme in fatty acid biosynthesis, acetyl CoA carboxylase (ACCase). The frequent use of AOPP and CHD herbicides has resulted in the development of resistance to these herbicides in many grass weed species. New herbicides that inhibit both the susceptible and resistant forms of ACCase in grass weeds would have obvious commercial appeal. In the present study, an attempt was made to identify molecules that target both the herbicide-sensitive and -resistant forms of ACCase. Seven experimental compounds, either CHD-like or AOPP-CHD hybrids, were synthesized and assayed against previously characterized susceptible and resistant forms of ACCase. All seven compounds inhibited ACCase from sensitive biotypes of Setaria viridis and Eleusine indica (I50 values from 6.4 to >100 microM) but were not particularly potent compared to some commercialized herbicides (I50 values of 0.08-5.6 microM). In almost all cases, the I50 values for each compound assayed against the resistant ACCases were higher than those against the corresponding sensitive ACCase, indicating reduced binding to the resistant ACCases. One compound, a CHD analogue, was almost equally effective against the resistant and susceptible ACCases, although it was not a very potent ACCase inhibitor per se (I50 of 51 and 76 microM against susceptible ACCase from S. viridis and E. indica, respectively). The AOPP-CHD hybrid molecules also inhibited some of the resistant ACCases, with I50 values ranging from 6.4 to 50 microM. These compounds may be good leads for developing ACCase inhibitors that target a wider range of ACCase isoforms, including those found in AOPP- and CHD-resistant weed biotypes.  相似文献   
62.
The present studies were conducted to isolate, select, identify and characterize gut bacteria as antimicrobial and growth promoting agent for the feed of economical y important ifsh Cirrhinus mrigala. ...  相似文献   
63.

De-oiled rice bran (DORB) is obtained after oil is removed from the rice bran. This is the commonly used ingredient in the feeding of Indian major carps due to its cheaper cost. DORB is used as a feed ingredient in cattle, poultry, and fish diet. Along with this, they are also used in making fiber-rich biscuits and extraction of an antioxidant compound like oryzanol and other industrial uses. Due to the increased competition, there will be a huge imbalance in the demand and supply for this ingredient in the years to come. DORB is associated with high fiber content, anti-nutrients, and non-starch polysaccharides which lead to its poor utilization resulting in a higher feed conversion ratio (FCR) in fish. Hence, the strategic utilization of this ingredient by solid-state fermentation, exogenous enzyme supplementation, and supplementing it with deficient nutrients like amino acids and fatty acids will help in improving the utilization of this ingredient.

  相似文献   
64.
Two experiments were conducted to investigate the effect of inland water salinity on growth performance, feed conversion efficiency and intestinal enzyme activity in grey mullet. In experiment I, a 90 day monoculture of grey mullet at different salinity levels (0, 10, 15, 20 and 25%) was carried out. The fingerlings were stocked at 5000 per hectare and fed on a supplementary diet at 5% BW d–1. This Study revealed that fish growth mean body weight (90.5 ± 4.5 g) and mean length (21.6 ± 0.4 cm), SGR (4.70%) and growth per day (0.99 g d–1) were significantly (p < 0.05) enhanced in fish maintained at 10% salinity in comparison with other treatments. Nutrient levels, phytoplankton population, NPP and chlorophyll a all decreased with an increase in salinity (>10%). In addition, zooplankton populations increased with an increase in the salinity level. Most of the other hydrochemical characteristics remained at optimal levels in all other treatments. Fish weight gain showed a significant positive correlation with productivity indicating parameters viz. alkalinity (r = 0.53), turbidity (r = 0.62), NPP (r = 0.75) and chlorophyll a (r = 0.46), clearly revealing that fish growth is also related to the trophic status of the ponds. In the second experiment (Experiment II), mullet fry were exposed to five different salinity levels (10, 15, 20, 25 and 30%) and maintained for 70 days in the laboratory. Significantly (p < 0.05) high growth, (SGR and per cent increase in body weight), feed conversion efficiency and intestinal enzyme activity were observed in the group maintained at 10 salinity in comparison with other groups maintained at similar salinity levels. Carcass composition, musc1e and liver glycogen levels were also significantly (p < 0.05) affected by salinity changes.  相似文献   
65.
66.
67.

Paratuberculosis (PTB) is a chronic infectious enteritis of ruminants, caused by Mycobacterium avium subspecies paratuberculosis (MAP) that brings huge economic loss to the dairy farmers. The study was conducted to explore the association of selected SNPs in IFNG, SLC11A1, ANKRA2 and PGLYRP1 genes with resistance to PTB disease in Indian cattle population. A case-control resource population was established based on the results of diagnostic tests used for detection of MAP infection status viz. ELISA, Johnin PPD test, faecal microscopy and IS900 blood PCR. The PCR-RFLP method was used for genotyping of SNPs. SNPs rs109453173 in SLC11A1, rs110853455 in IFNG and rs41933863 in ANKRA2 genes were significantly (P<0.05) associated with resistance to MAP infection. For SNP rs109453173, GG genotype and G allele was found to be associated with resistance against MAP infection than CC and CG genotypes and C allele, respectively. For SNP rs110853455, AG genotype was found to be associated with susceptibility to MAP infection than AA and GG genotype. For SNP rs41933863, the AG genotype provided three and six times more resistance against MAP infection than GG and AA genotype. The results of this study are suggestive of SNPs rs109453173, rs110853455 and rs41933863 as potential markers for screening MAP resistant cattle and a breeding programme favouring GG genotype and G allele for rs109453173, AG genotype for rs41933863 and against AG genotype for rs110853455 might confer resistance against MAP infection in Indian cattle. However, investigation of these SNPs in an independent and larger population will warrant the strength of association for resistance against MAP infection in cattle.

  相似文献   
68.
Kumar  Raj  Bhardwaj  A. K.  Rao  B. K.  Vishwakarma  A. K.  Kakade  Vijaysinha  Dinesh  D.  Singh  Gaurav  Kumar  Gopal  Pande  V. C.  Bhatnagar  P. R.  Bagdi  G. L. 《Journal of Soils and Sediments》2021,21(2):1232-1242
Journal of Soils and Sediments - Soil erosion and loss threatens vast tracts of agricultural and non-agricultural land, worldwide. High soil erosion severely affects establishment of vegetation via...  相似文献   
69.
Over the last few years, significant research has been conducted in the construction of artificial bone scaffolds. In the present study, different types of polymer scaffolds, such as chitosan-alginate (Chi-Alg) and chitosan-alginate with fucoidan (Chi-Alg-fucoidan), were developed by a freeze-drying method, and each was characterized as a bone graft substitute. The porosity, water uptake and retention ability of the prepared scaffolds showed similar efficacy. The pore size of the Chi-Alg and Chi-Alg-fucoidan scaffolds were measured from scanning electron microscopy and found to be 62–490 and 56–437 µm, respectively. In vitro studies using the MG-63 cell line revealed profound cytocompatibility, increased cell proliferation and enhanced alkaline phosphatase secretion in the Chi-Alg-fucoidan scaffold compared to the Chi-Alg scaffold. Further, protein adsorption and mineralization were about two times greater in the Chi-Alg-fucoidan scaffold than the Chi-Alg scaffold. Hence, we suggest that Chi-Alg-fucoidan will be a promising biomaterial for bone tissue regeneration.  相似文献   
70.
Genetic Resources and Crop Evolution - Agricultural production is facing serious threat from various biotic and abiotic stresses specifically under climatic challenges. It is becoming increasingly...  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