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   1359篇
  免费   51篇
  国内免费   3篇
林业   99篇
农学   70篇
基础科学   17篇
  257篇
综合类   89篇
农作物   140篇
水产渔业   150篇
畜牧兽医   432篇
园艺   25篇
植物保护   134篇
  2023年   15篇
  2022年   30篇
  2021年   63篇
  2020年   74篇
  2019年   61篇
  2018年   51篇
  2017年   58篇
  2016年   49篇
  2015年   55篇
  2014年   56篇
  2013年   117篇
  2012年   86篇
  2011年   104篇
  2010年   49篇
  2009年   31篇
  2008年   58篇
  2007年   52篇
  2006年   33篇
  2005年   33篇
  2004年   34篇
  2003年   34篇
  2002年   25篇
  2001年   14篇
  2000年   14篇
  1999年   13篇
  1998年   4篇
  1997年   7篇
  1996年   9篇
  1995年   8篇
  1994年   6篇
  1993年   9篇
  1991年   11篇
  1990年   10篇
  1989年   14篇
  1988年   8篇
  1987年   10篇
  1986年   9篇
  1985年   10篇
  1984年   12篇
  1983年   9篇
  1981年   7篇
  1979年   5篇
  1978年   5篇
  1976年   4篇
  1975年   7篇
  1973年   4篇
  1972年   4篇
  1971年   5篇
  1970年   5篇
  1969年   4篇
排序方式: 共有1413条查询结果,搜索用时 295 毫秒
991.
992.
993.
994.
995.
The opsonization and lysis of different protozoa by antibodies and/or complement was followed using luminol-dependent chemiluminescence and bioluminescence. The addition of immune serum to variable antigen type populations of Trypanosoma evansi led to the specific opsonization of trypanosomes resulting in an intense metabolic activation and chemiluminescence response of phagocytic cells. In comparison to those of uninfected control mice, the phagocytosis of coccidia merozoites by spleen cells from mice infected with Eimeria falciformis was enhanced during the acute stage of a primary infection. Opsonizing activity was demonstrated in phosphate-buffered saline extracts of gut contents of mice infected for 10 days. The incubation of E. falciformis merozoites together with guinea-pig complement resulted in slow lysis of the cells. The addition of mouse serum collected greater than 6 days after an infection led to an accelerated lysis of the merozoites, indicating the appearance of complement-fixing antibodies in the serum. Heat-inactivated immune serum alone had no lysing activity on merozoites. In the presence of complement, bovine lymphoblastoid cells infected with Theileria annulata were lysed by anti-lymphoblastoid cell serum raised in mice but not by serum from cattle which had developed immunity to Theileria annulata.  相似文献   
996.
Total hepatic microsomal cytochrome P450 (CYP) content as well as in vitro CYP mediated activities for five substrates [bufuralol 1-hydroxylation, ethoxyresorufin O-deethylation, S-mephenytoin 4-hydroxylation, testosterone 6beta-hydroxylation, and tolbutamide hydroxylation] were measured in specific pathogen free male Japanese leghorn chickens and male beagle dogs. The Vmax, Km and intrinsic clearance (Vmax/Km) for these substrates were calculated and compared between animal species in order to evaluate the drug catalytic activity in chicken liver. The total CYP content in chicken (0.296 +/- 0.04 nmol/mg microsomal protein) was close to levels reported for other species including humans, cats, pigs and some nonmammalian vertebrates (e.g. snakes, frogs and trout fish), but was lower than levels measured in dogs (1.11 +/- 0.22) or recorded in guinea-pigs, hamsters, monkeys, mice, rabbits, rats, horse and ruminants. Bufuralol 1-hydroxylation, ethoxyresorufin O-deethylation, S-mephenytoin 4-hydroxylation, and testosterone 6beta-hydroxylation were lower in chickens than in dogs based on intrinsic clearance. On the other hand, tolbutamide hydroxylation was markedly higher in chickens than in dogs.  相似文献   
997.
998.
The sequential development of the clinical signs and lesions in the organs of desert sheep and Nubian goats dosed with Jatropha curcas seeds at 0.05, 0.5 and 1 g/kg/day was studied. Diarrhoea, reduced water consumption, dehydration, sunken eyes, inappetence and loss in condition were the important signs of J curcas poisoning in sheep and goats. The main pathological changes were haemorrhage in the rumen, reticulum, lungs, kidneys and heart, catarrhal and/or haemorrhagic enteritis, hepatic fatty change, pulmonary congestion and oedema and straw-coloured fluid in serous cavities. An increase in the concentrations of AST, ammonia, potassium and sodium and a decrease in total protein and calcium were detected in the serum. Haematological changes were haemoconcentration and leucocytosis.  相似文献   
999.
1000.
Hydrophobic fibers are highly crysta lline and non-polar polymers hence pose a big problem for dyers. Modified acrylic fiber containing different amounts of amidoxime groups as a function of the nitrogen content was obtained and dyed with curcumin and madder natural dyes. The dyeing parameters, such as dye concentration, dye bath pH, salt concentration, temperature, and time and the effect of alum and ferrous sulfate used as mordants were investigated. Compared with the dyeings obtained from modified acrylics, those of blank samples appeared less in color strength values. The color strength was proportional to the nitrogen content of the sample and the maximum value was obtained at pH 2 and pH 5 using madder and curcumin, respectively. The fixation of the dye molecules to the modified acrylic fibers was investigated to show mainly ionic and physical bonds. The washing, perspiration, and rubbing fastness properties for the dyed samples were enhanced by application of alum. The light fastness ratings were also improved using ferrous sulfate especially for the case of the samples dyed with madder.  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