全文获取类型
收费全文 | 288篇 |
免费 | 2篇 |
专业分类
林业 | 1篇 |
农学 | 4篇 |
8篇 | |
综合类 | 247篇 |
农作物 | 1篇 |
水产渔业 | 2篇 |
畜牧兽医 | 25篇 |
园艺 | 1篇 |
植物保护 | 1篇 |
出版年
2023年 | 2篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2014年 | 1篇 |
2012年 | 2篇 |
2011年 | 4篇 |
2010年 | 1篇 |
2009年 | 1篇 |
2005年 | 1篇 |
2003年 | 5篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1990年 | 1篇 |
1989年 | 16篇 |
1988年 | 29篇 |
1987年 | 30篇 |
1986年 | 37篇 |
1985年 | 32篇 |
1984年 | 29篇 |
1983年 | 26篇 |
1982年 | 23篇 |
1981年 | 16篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1971年 | 3篇 |
1970年 | 1篇 |
1966年 | 1篇 |
1958年 | 1篇 |
1945年 | 1篇 |
排序方式: 共有290条查询结果,搜索用时 437 毫秒
271.
272.
273.
274.
275.
Lewin G 《The Journal of small animal practice》2003,44(8):346-351
The use of a split eyelid flap to reconstruct both a normal palpebral aperture and a smooth, hairless eyelid margin following the excision of eyelid neoplasia, in a series of seven dogs, is described. The patterns of reconstruction used in the procedure are discussed, and previously reported methods of eyelid reconstruction are reviewed. 相似文献
276.
J E Beever P D George R L Fernando C J Stormont H A Lewin 《Journal of animal science》1990,68(2):337-344
Segregation of polymorphic marker genes in a paternal half-sib family of Angus cattle was used to detect associations between genetic markers and quantitative traits. The half-sib family selected (n = 146) had a sire that was heterozygous at six polymorphic marker loci; BoLA-A (class I major histocompatibility complex), B, C and F blood group systems, serum transferrin and vitamin D binding protein. Segregation of alleles fit the expected ratios for all marker loci. Performance data analyzed for all half-sibs included birth, 205-d and 365-d adjusted weights and pre- and post-weaning average daily gains. Carcass data for steers (n = 61) included carcass weight, rib-eye area, 12th rib fat thickness, percent kidney, heart and pelvic fat and yield grade. Least squares means were compared for differences in performance and carcass traits between groups of half-sibs that inherited alternative paternal alleles. Significant effects were found for two of the six marker systems. Half-sibs that inherited the chromosomal segment (CS) marked by the RBC-B system BGKOxY2A'O' phenogroup had heavier 205-d (9.1 kg) and 365-d (17.3 kg) adjusted weights, faster preweaning average daily gains (.04 kg) and less fat thickness (-2.6 mm) than sibs that inherited the CS marked by I2Y2E'1Y'. Also, sibs that inherited the CS marked by the BoLA-w2 allele had larger rib-eye areas (4.1 cm2) than sibs that inherited BoLA-w28. These data indicate the probable presence of genes linked to the RBC-B and BoLA systems that affect preweaning growth and lean muscle content. 相似文献
277.
278.
Age factors loom in parkinsonian research 总被引:1,自引:0,他引:1
R Lewin 《Science (New York, N.Y.)》1986,234(4781):1200-1201
279.
W C Davis S Marusic H A Lewin G A Splitter L E Perryman T C McGuire J R Gorham 《Veterinary immunology and immunopathology》1987,15(4):337-376
We examined the potential of developing a set of species specific and cross reactive monoclonal antibodies (MoAbs) for use in the study of the phylogenetic and functional relation of class I and class II antigens of the major histocompatibility complex (MHC) and leukocyte differentiation antigens in cattle and other species. Comparing immunization strategies demonstrated the number of hybrids producing cross reactive antibodies can be increased by hyperimmunization of mice with lymphoid cells from multiple species. Comparing various methods of assay (antibody-complement mediated cytotoxicity [CT], enzyme linked immunosorbent assay [ELISA] and flow microfluorimetry [FMF]), revealed FMF is the most useful technique for the primary assay of hybridomas producing MoAbs of potential interest. By using dual parameter and dual fluorescence analysis, we could determine whether a given MoAb reacted with mononuclear cells (lymphocytes and monocytes) and/or granulocytes, and also whether any two MoAbs of different isotype and specificity recognized antigens present on identical or separate populations of leukocytes. Comparing the patterns of MoAb reactivity with leukocytes obtained from cows, goats, sheep, pigs, horses and humans, as well as comparing the patterns of reactivity with a panel of lymphoid cell lines derived from cattle (with enzootic bovine leukemia) and humans (with various forms of leukemia), revealed sets of MoAbs reactive with unique antigenic determinants present on BoLA class I (15 MoAbs) and class II (9 MoAbs) antigens, and also MoAbs reactive with determinants present on leukocyte differentiation antigens (36 MoAbs). Dual fluorescence analysis demonstrated the antigens detected by some MoAbs are predominantly expressed on one lineage of leukocytes while others are expressed on two or more lineages of leukocytes. Dual and single fluorescence analysis also demonstrated the PNA receptor(s) is: expressed on T cells, granulocytes and class II antigen monocytes and absent or expressed in low amount on sIgM+ B cells and a newly defined Non T/Non B population of cells. The strategies described for identifying and analyzing the specificity of MoAbs demonstrate the feasibility of developing a set of cross reactive MoAbs for identifying homologous molecules in multiple species and delineating their functional and phylogenetic relation. 相似文献
280.
The uncertain perils of an invisible landscape 总被引:1,自引:0,他引:1
R Lewin 《Science (New York, N.Y.)》1988,240(4858):1405-1406