全文获取类型
收费全文 | 435篇 |
免费 | 47篇 |
国内免费 | 1篇 |
专业分类
林业 | 13篇 |
农学 | 8篇 |
基础科学 | 22篇 |
17篇 | |
综合类 | 126篇 |
农作物 | 5篇 |
水产渔业 | 15篇 |
畜牧兽医 | 261篇 |
园艺 | 5篇 |
植物保护 | 11篇 |
出版年
2023年 | 3篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 13篇 |
2017年 | 11篇 |
2016年 | 9篇 |
2015年 | 12篇 |
2014年 | 12篇 |
2013年 | 13篇 |
2012年 | 16篇 |
2011年 | 20篇 |
2010年 | 17篇 |
2009年 | 13篇 |
2008年 | 14篇 |
2007年 | 26篇 |
2006年 | 10篇 |
2005年 | 11篇 |
2004年 | 10篇 |
2003年 | 10篇 |
2002年 | 15篇 |
2001年 | 11篇 |
2000年 | 7篇 |
1999年 | 11篇 |
1998年 | 10篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 15篇 |
1991年 | 26篇 |
1990年 | 12篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 5篇 |
1971年 | 5篇 |
1968年 | 4篇 |
1967年 | 5篇 |
1925年 | 2篇 |
1922年 | 3篇 |
排序方式: 共有483条查询结果,搜索用时 281 毫秒
31.
QTL controlling partial resistance to Stagonospora nodorum leaf blotch in winter wheat cultivar Alba 总被引:1,自引:1,他引:1
Edward Arseniuk Pawel C. Czembor Andrzej Czaplicki Qijian Song Perry B. Cregan David L. Hoffman Peter P. Ueng 《Euphytica》2004,137(2):225-231
Stagonospora nodorum blotch (SNB) is an important foliar and glume disease in cereals. Inheritance of SNB resistance in wheat appears quantitative. The development of partially resistant cultivars seems to be the only effective way to combat the pathogen. Partial resistance components like length of incubation period (INC), disease severity (DIS) and length of latent period (LAT) were evaluated on a population of doubled-haploids derived from a cross between the partially resistant cultivar Alba and the susceptible cultivar Begra. Experiments were conducted in controlled environments and the fifth leaf was examined. Molecular analyses were based on bulked segregant analyses (BSA) and screening with 240 microsatellites DNA markers. The QTL analysis revealed QTL on chromosome 6AL (designated as QSnl.ihar-6A) and putative QTL on chromosome 6D. The QSnl.ihar-6A accounted for 36% of the phenotypic variance for DIS and 14% for INC. The putative QTL accounted for 10% of the variability in INC and 8% of DIS components of SNB resistance. 相似文献
32.
Protection against malaria by vaccination with sporozoite surface protein 2 plus CS protein. 总被引:23,自引:0,他引:23
S Khusmith Y Charoenvit S Kumar M Sedegah R L Beaudoin S L Hoffman 《Science (New York, N.Y.)》1991,252(5006):715-718
The circumsporozoite (CS) protein has been the target for development of malaria sporozoite vaccines for a decade. However, immunization with subunit vaccines based on the CS protein has never given the complete protection found after immunization with irradiated sporozoites. BALB/c mice immunized with irradiated Plasmodium yoelii sporozoites produced antibodies and cytotoxic T cells against a 140-kilodalton protein, sporozoite surface protein 2 (SSP2). Mice immunized with P815 cells that had been transfected with either SSP2 or CS genes were partially protected, and those immunized with a mixture of SSP2 and CS transfectants were completely protected against malaria. These studies emphasize the importance of vaccine delivery systems in achieving protection and define a multi-antigen sporozoite vaccine. 相似文献
33.
Hoffman JH Hodges RR McElroy MB Donahue TM Kolpin M 《Science (New York, N.Y.)》1979,203(4382):800-802
Initial examination of data from the neutral mass spectrometer on the Pioneer Venus sounder probe indicates that the abundances of argon-36, argon-38, and neon-20 in the Venus atmosphere are much higher than those of the corresponding gases in Earth's atmosphere, although the abundance of radiogenic argon-40 is apparently similar for both planets. The lower atmosphere of Venus includes significant concentrations of various gaseous sulfur compounds. The inlet leak to the mass spectrometer was temporarily blocked by an apparently liquid component of the Venus clouds during passage through the dense cloud layer. Analysis of gases released during the evaporation of the droplets shows the presence of water vapor to some compound or compounds of sulfur. 相似文献
34.
Hoffman WA 《Science (New York, N.Y.)》1927,66(1716):484-485
35.
Hoffman JE McElroy K Lee DH Lang KM Eisaki H Uchida S Davis JC 《Science (New York, N.Y.)》2002,297(5584):1148-1151
Scanning tunneling spectroscopy of the high-Tc superconductor Bi2Sr2CaCu2O8+delta reveals weak, incommensurate, spatial modulations in the tunneling conductance. Images of these energy-dependent modulations are Fourier analyzed to yield the dispersion of their wavevectors. Comparison of the dispersions with photoemission spectroscopy data indicates that quasiparticle interference, due to elastic scattering between characteristic regions of momentum-space, provides a consistent explanation for the conductance modulations, without appeal to another order parameter. These results refocus attention on quasiparticle scattering processes as potential explanations for other incommensurate phenomena in the cuprates. The momentum-resolved tunneling spectroscopy demonstrated here also provides a new technique with which to study quasiparticles in correlated materials. 相似文献
36.
37.
38.
Progress toward malaria preerythrocytic vaccines 总被引:5,自引:0,他引:5
S L Hoffman V Nussenzweig J C Sadoff R S Nussenzweig 《Science (New York, N.Y.)》1991,252(5005):520-521
39.
Welfare dependence within and across generations 总被引:2,自引:0,他引:2
A central question in the debate about the effects of welfare programs is whether their intended positive results--providing needed resources to recipients and their children--outweigh any unintended negative results--for example, the breaking up of families, reduction in work effort, or the fostering of a welfare "culture" that is passed on from parent to child. Recent research shows that although work effort is affected adversely by the generosity of welfare programs, effects on family structure appear quite weak, most welfare experiences are relatively short, and the majority of women who grew up in homes heavily dependent on welfare do not rely on those programs when they are young adults. 相似文献
40.
Experimentally damaged leaves of Cucurbita moschata mobilize substances to the damaged region within 40 minutes. These substances stimulate feeding by Acalymma vittata (Coleoptera: Chrysomelidae) and inhibit feeding by Epilacha tredecimnotata (Coleoptera: Coccinelidae). Under natural conditions, Epilachna cuts a circular trench in the leaf before feeding on the encircled leaf material, thus preventing mobilization of the deterrent substances to the feeding area. 相似文献