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   197篇
  免费   7篇
林业   16篇
农学   5篇
  27篇
综合类   15篇
农作物   2篇
水产渔业   22篇
畜牧兽医   101篇
园艺   4篇
植物保护   12篇
  2023年   1篇
  2022年   3篇
  2021年   2篇
  2019年   3篇
  2018年   3篇
  2017年   2篇
  2016年   5篇
  2015年   6篇
  2014年   6篇
  2013年   14篇
  2012年   7篇
  2011年   15篇
  2010年   2篇
  2009年   2篇
  2008年   10篇
  2007年   7篇
  2006年   9篇
  2005年   8篇
  2004年   7篇
  2003年   8篇
  2002年   7篇
  2001年   11篇
  2000年   7篇
  1999年   7篇
  1998年   2篇
  1997年   2篇
  1996年   2篇
  1995年   1篇
  1994年   2篇
  1992年   2篇
  1991年   3篇
  1990年   2篇
  1989年   5篇
  1988年   4篇
  1987年   7篇
  1986年   4篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1975年   2篇
  1974年   3篇
  1973年   3篇
  1972年   1篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
  1966年   1篇
排序方式: 共有204条查询结果,搜索用时 10 毫秒
131.
ABSTRACT:   The effects of dietary taurine levels and lipid contents on the conjugated bile acid composition and growth performance of juvenile Japanese flounder Paralichthys olivaceus were investigated. Six types of diet (three different levels of taurine at two different levels of lipid) were fed to juveniles (average body weight, 0.04 g). Fishmeal that was washed with 70% ethanol to remove taurine was used as the sole protein source. Feeding experiments were carried out at 20°C for 6 weeks. At the end of the experiments, fish were weighed and analyzed for free amino acids in the body and the composition of the conjugated bile acids. The body weight and percent weight gain of the juveniles were improved by the dietary taurine supplementation. The taurine contents of the whole body and tissues increased with the increase of the dietary taurine contents. The conjugated bile acids in the gall bladder consisted of taurocholic acid and taurochenodeoxycholic acid, which increased with the increase of the dietary taurine level. Taurocholic acid accounted for more than 95% of the total conjugated bile acids. This indicates that taurine is the sole amino acid to conjugate bile acid in Japanese flounder.  相似文献   
132.
Repetitive extragenic palindromic (REP)-PCR and enterobacterial repetitive intergenic consensus (ERIC)-PCR analysis was applied to the identification and classification of local isolates of 44 Bradyrhizobium japonicum, 7 Sinorhizobium meliloti, 10 Rhizobium leguminosarum strains from Japan and Thai. Using genomic DNA of the 61 strains, both REP and ERIC primers induced reproducible PCR band patterns, although REP-PCR generated more bands and appeared to be more useful for distinguishing the isolates from each other. Using mixed matrix data from both REP- and ERIC-PCR data, it become possible to distinguish all the isolates analyzed in this experiment from each other. When cluster analysis was applied to both PCR matrix data of 44 B. japonicum isolates, only the REP-PCR dendrogram showed a grouping profile corresponding to the exo-polysaccharide phenotype with a exceptions. When the matrix data of R. leguminosarum and S. meliloti were subjected to cluster analysis, S. meliloti appeared to form a different subgroup from R. leguminosarum in the dendrogram of REP-PCR data except for one strain. In the case of ERIC-PCR, isolates of R. leguminosarum from northern Thailand formed a separate subgroup from other R. leguminosarum and S. meliloti which were dispersed in the dendrogram. These data suggest that REP-PCR and ERIC-PCR were effective for the identification of individual isolates even though the isolates showed a wide genetic diversity and the same phenotype. When the data of the local isolates from Japan and Thailand were subjected to cluster analysis, REP- and ERIC-PCR analysis revealed different grouping characteristics.  相似文献   
133.
Inactivated influenza virus vaccine prepared from a non-pathogenic influenza virus strain A/duck/Hokkaido/Vac-1/2004 (H5N1) from the virus library conferred protective immunity to chickens against the challenge of antigenically drifted highly pathogenic avian influenza virus (HPAIV), A/whooper swan/Hokkaido/1/2008 (H5N1). The efficacy of the vaccine was comparable to that prepared from genetically modified HPAIV strain deltaRRRRK rg-A/ whooper swan/Mongolia/3/2005 (H5N1), which is more antigenically related to the challenge virus strain, in chickens.  相似文献   
134.
Hepatoblastomas are neoplasms that originate from putative pluripotential stem cells of the liver. A hepatic mass from an 8-year-old Abyssinian cat was composed of cords and sheets of neoplastic cells, with scattered rosettes and small ductal structures. Most neoplastic cells had a pale eosinophilic cytoplasm and a round to ovoid nucleus. The tumor also had short spindle cells with an oval nucleus. Immunohistochemically, neoplastic cells were weakly positive for embryonic hepatocellular markers, such as alpha-fetoprotein and cytokeratin (CK) 8/18, but negative for the hepatocellular marker Hepatocyte Paraffin 1. The cells were also positive for CD56/neural cell adhesion molecule and for the biliary epithelial markers CK 7, CK 8/18, CK CAM5.2, and vimentin, but negative for CK 20. Some neoplastic cells expressed neuroectodermal or neuroendocrine markers, such as protein gene product 9.5 and synaptophysin, but were negative for chromogranin A and not argyrophilic by the Grimelius technique. The cat died soon after the biopsy without clinical improvement.  相似文献   
135.
We report the fabrication of transparent field-effect transistors using a single-crystalline thin-film transparent oxide semiconductor, InGaO3(ZnO)5, as an electron channel and amorphous hafnium oxide as a gate insulator. The device exhibits an on-to-off current ratio of approximately 106 and a field-effect mobility of approximately 80 square centimeters per volt per second at room temperature, with operation insensitive to visible light irradiation. The result provides a step toward the realization of transparent electronics for next-generation optoelectronics.  相似文献   
136.
Inorganic polyphosphate (polyP), a polymer of hundreds of phosphate (Pi) residues, accumulates in Escherichia coli in response to stresses, including amino acid starvation. Here we show that the adenosine 5'-triphosphate-dependent protease Lon formed a complex with polyP and degraded most of the ribosomal proteins, including S2, L9, and L13. Purified S2 also bound to polyP and formed a complex with Lon in the presence of polyP. Thus, polyP may promote ribosomal protein degradation by the Lon protease, thereby supplying the amino acids needed to respond to starvation.  相似文献   
137.
The eel has long been esteemed as an important food fish in the world, especially in Japan, and has been used as an experimental fish for many fields of fish physiology. However, the decreases in eel resources have been a serious concern in recent years. The catches of glass eels as seedlings for aquaculture have shown a long-term decrease in both Europe and East Asia. To increase eel resources, the development of techniques for artificial induction of maturation and spawning and rearing their larvae have been eagerly desired. Recent progress of reproductive physiology of fish, especially mechanisms of oocyte maturation and ovulation in female and of spermatozoa maturation in male, facilitate to establish techniques for hormonal induction of maturation and spawning in sexually immature eels. With persistent effort to development of rearing techniques of larvae, we have first succeeded to produce glass eel. These applied techniques are may contribute to understand the basic reproductive physiology of the eel.  相似文献   
138.
139.
140.
Summary Barley plants are able to accumulate glycinebetaine (betaine) at high levels in their leaves in response not only to water and salt stress but also to cold stress. Such accumulation of betaine during acclimation to cold is associated to some extent with freezing tolerance in leaves of barley plants, as previously demonstrated with near-isogenic lines that differed only in a single gene for the spring type of growth habit (Plant, Cell and Enyironment 17: 89–95, 1994). We now present evidence that the levels of betaine accumulated during cold acclimation might be associated with the earliness or lateness of the maturity of cultivars, namely, that late cultivars accumulate more betaine than early cultivars. Moreover, the grade of the vermalization requirement of the cultivars seemed unlikely to be associated with the level of betaine acumulated during cold acclimation. However, the trait that controlled accumulation of betaine during cold acclimation was not linked with the earliness or lateness of the maturity of cultivars. The higher levels of betaine in the late cultivars might have resulted from co-selection for lateness of maturity and freezing tolerance, which is generally a requirement in the areas of Japan where such late cultivars were originally cultivated.  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