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   305篇
  免费   9篇
  国内免费   4篇
林业   30篇
农学   11篇
基础科学   2篇
  57篇
综合类   21篇
农作物   7篇
水产渔业   33篇
畜牧兽医   119篇
园艺   6篇
植物保护   32篇
  2022年   8篇
  2021年   5篇
  2019年   1篇
  2018年   3篇
  2017年   6篇
  2016年   5篇
  2015年   9篇
  2014年   9篇
  2013年   21篇
  2012年   11篇
  2011年   29篇
  2010年   11篇
  2009年   7篇
  2008年   28篇
  2007年   24篇
  2006年   31篇
  2005年   15篇
  2004年   8篇
  2003年   10篇
  2002年   7篇
  2001年   16篇
  2000年   6篇
  1999年   7篇
  1998年   2篇
  1997年   1篇
  1996年   1篇
  1995年   4篇
  1994年   1篇
  1993年   2篇
  1992年   3篇
  1991年   3篇
  1990年   4篇
  1988年   2篇
  1987年   3篇
  1986年   5篇
  1985年   1篇
  1984年   2篇
  1981年   1篇
  1977年   1篇
  1976年   2篇
  1975年   1篇
  1973年   2篇
排序方式: 共有318条查询结果,搜索用时 0 毫秒
231.
The study was designed to investigate the effect of Rhodobacter capsulatus on serum and meat cholesterol, fatty acid composition in meat, as well as meat quality of finishing pigs. A total of 16 120-day-old Landrace female pigs of about 60 kg initial body weight were randomly assigned into two groups. The pigs were fed a supplemented diet with 0.04% dietary R. capsulatus or a control diet for 60 days. Total cholesterol and low density lipoprotein-cholesterol concentration in serum was significantly lowered ( P  < 0.05) in the pigs fed the R. capsulatus supplemented diet compared to the control diet. Carcass weight, carcass length, shoulder fat, back fat and loin fat thickness, longissimus muscle (LM) area, and color score did not differ significantly between the pigs fed the R. capsulatus supplemented diet and control diet. Among the nutrient composition of LM meat, neutral fat and triglyceride concentration were significantly ( P  < 0.05) reduced in the finishing pigs by dietary supplementation of R. capsulatus . The proportions of n-6 PUFA were higher ( P  < 0.05) in the pigs fed the R. capsulatus supplemented diet than in the pigs fed the control diet. The supplementation of dietary R. capsulatus to finishing pig diet played important roles in reducing serum cholesterol and meat triglycerides, as well as in increasing polyunsaturated fatty acid content in LM meat.  相似文献   
232.
alpha-klotho was identified as a gene associated with premature aging-like phenotypes characterized by short lifespan. In mice, we found the molecular association of alpha-Klotho (alpha-Kl) and Na+,K+-adenosine triphosphatase (Na+,K+-ATPase) and provide evidence for an increase of abundance of Na+,K+-ATPase at the plasma membrane. Low concentrations of extracellular free calcium ([Ca2+]e) rapidly induce regulated parathyroid hormone (PTH) secretion in an alpha-Kl- and Na+,K+-ATPase-dependent manner. The increased Na+ gradient created by Na+,K+-ATPase activity might drive the transepithelial transport of Ca2+ in cooperation with ion channels and transporters in the choroid plexus and the kidney. Our findings reveal fundamental roles of alpha-Kl in the regulation of calcium metabolism.  相似文献   
233.
ABSTRACT:   Relationships between otolith and somatic sizes were examined for Japanese anchovy Engraulis japonicus and sardine Sardinops melanostictus larvae collected broadly in the western North Pacific, based on a substantial data set derived from a previous paper. Allometric formulae showed close fits to the relationships between otolith radius and standard length, and the formulae differed between anchovy and sardine larvae. Despite the high correlations, the effect of somatic growth rate on the otolith and somatic size relationship (the 'growth effect') was significantly detected for both anchovy and sardine larvae. Slower growing larvae tended to have larger otoliths than faster growing conspecifics at the same somatic size. This growth effect was more obvious for sardine larvae than for anchovy larvae, probably because of their differential responses of somatic growth to temperature shifts. The growth effect could lead to the possibility of biases in the back-calculation and size estimation processes. As the growth effect is considered to be a general phenomenon and its extent to be species-specific, the relationship between otolith and somatic size and its uncoupling should be scrutinized before application of techniques based on the otolith and somatic size correlation.  相似文献   
234.
Porcine IL-12Rbeta2 gene was cloned from mRNA preparation of mitogen-activated peripheral blood mononuclear cells (PBMCs), and its complete nucleotide sequence was determined. To confirm the biological function, the entire open reading frame (ORF) was re-cloned into a mammalian expression vector, pcDNA3.1/Zeo(+), at the downstream of CMV promoter, and introduced to a Th1-like human lymphoma cell line, Jurkat E6-1. Antibiotic-resistant cells retaining the expression construct were selected then, isolated by the limiting dilution method. An established clone (10B10) constitutively expressed chimeric IL-12Rs composed of intrinsic (human) beta1 and extrinsic (porcine) beta2 subunits, and produced interferon (IFN)-gamma in response to IL-12 of both species with optimal PHA/PMA stimulation. The production of IFN-gamma was observed as early as 42 h after culture and appeared to be dose-dependent within the range between 20 and 2000 pg/ml. Thus, this clone not only reacts with IL-12 of both species but also provides a useful tool for quick and sensitive detection of IL-12 bioactivity.  相似文献   
235.
This comparative study was to investigate the hypocholesterolemic effects of dietary Rhodopseudomonas palustris and Rhodobacter capsulatus on rats fed a high cholesterol diet. Thirty male Wister–Imamichi rats were assigned to three groups and fed on either a high cholesterol diet, or a high cholesterol diet supplemented with 2.0% R. palustris or R. capsulatus for 4 weeks. Compared to the control diet, both of the R. palustris and R. capsulatus supplemented diets significantly reduced the serum cholesterol, triglycerides, low‐density lipoprotein, very low density lipoprotein cholesterol and hepatic triglycerides, but increased hepatic cholesterol in rats. In addition, both of the R. palustris and R. capsulatus supplemented diets may reduce the risk of atherosclerosis, as the ratio of high density lipoprotein cholesterol to the total cholesterol was significantly higher than in the control group (P < 0.05). Both the R. palustris and R. capsulatus supplemented diets led to an increase in the serum palmitic acid, compared with the oleic acid and linoleic acid. No significant differences were postulated between the rats fed R. palustris and R. capsulatus supplemented diets during the 4 weeks of the experimental period. Thus, the results may suggest that both R. palustris and R. capsulatus can contribute significant health benefits and seems to be feasible to investigate in future research.  相似文献   
236.
Two field strains of avian infectious bronchitis virus were tested in specific pathogen-free chickens for interferon induction, growth and stimulation of virus-neutralizing antibody. Both strains induced interferon in lungs and trachea and neither strain induced it in kidneys. Strain Kagoshima-34, isolated from the kidneys of a chicken that had died of nephrosis/nephritis, induced interferon earlier than Strain Tottori-2, which was isolated from the trachea of a chicken with respiratory disease. Virus growth was generally more prolonged with Kagoshima-34, especially in the kidneys, but Tottori-2 persisted longer in the lungs.  相似文献   
237.
238.
The occurrence and density of Pacific saury Cololabis saira larvae and juveniles were examined in relation to environmental factors during the winter spawning season in the Kuroshio Current system, based on samples from extensive surveys off the Pacific coast of Japan in 2003–2012. Dense distributions of larvae and juveniles were observed in areas around and on the offshore side of the Kuroshio axis except during a large Kuroshio meander year (2005). The relationships of larval and juvenile occurrence and density given the occurrence to sea surface temperature (SST), salinity (SSS), and chlorophyll‐a concentration (CHL) were examined by generalized additive models for 10‐mm size classes up to 40 mm. In general, the optimal SST for larval and juvenile occurrence and density given the occurrence was consistently observed at 19–20°C. The patterns were more complex for SSS, but a peak in occurrence was observed at 34.75–34.80. In contrast, there were negative relationships of occurrence and density given the occurrence to CHL. These patterns tended to be consistent among different size classes, although the patterns differed for the smallest size class depending on environmental factors. Synthetically, the window for spawning and larval and juvenile occurrence and density seems to be largely determined by physical factors, in particular temperature. The environmental conditions which larvae and juveniles encounter would be maintained while they are transported. The survival success under the physically favorable but food‐poor conditions of the Kuroshio Current system could be key to their recruitment success.  相似文献   
239.
The leukocyte populations of periparturient dairy cows were analyzed after administration of active egg white/Clostridium butyricum Miyairi additive. Sixty-eight Holstein milking cows were divided into 3 groups. Group A was administered active egg white product (AEWP)/Clostridium butyricum Miyairi 588 (Miyairi 588) additive (n=23). Group B was administered Miyairi 588 only (n=23), and Group C was the control group (n=22). The challenged groups were administered 100 g of AEWP + Miyairi 588, or Miyairi 588 alone, daily for 60 days from 1 month before until 1 month after paturition. Blood samples were collected from all groups three times (1 month before, 1 week after and 1 month after parturition) for analysis of the peripheral leukocyte population. The results showed significantly higher numbers of CD4+ cells in Group A compared with Group C 1 week after paturition. AEWP/Miyairi 588 additive may enhance the number of CD4+ T cells in periparturient dairy cows.  相似文献   
240.
A seroepidemiological survey of Neospora caninum infection among dogs in Japan was conducted using species-specific enzyme-linked immunosorbent assay with recombinant surface antigen (Nc-SAG1t). Among 1,206 dogs examined, 126 dogs (10.4%) from 30 prefectures from Hokkaido to Okinawa were positive to N. caninum infections, which were more frequently detected in females than males. Siberian Huskies showed the highest positive rate compared with the other breeds. Dogs with pyometra and diabetes mellitus showed the higher positive rates than dogs with other diseases or without diseases.  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