全文获取类型
收费全文 | 621篇 |
免费 | 36篇 |
国内免费 | 2篇 |
专业分类
林业 | 78篇 |
农学 | 32篇 |
基础科学 | 4篇 |
63篇 | |
综合类 | 31篇 |
农作物 | 22篇 |
水产渔业 | 97篇 |
畜牧兽医 | 284篇 |
园艺 | 9篇 |
植物保护 | 39篇 |
出版年
2022年 | 4篇 |
2021年 | 21篇 |
2020年 | 13篇 |
2019年 | 18篇 |
2018年 | 15篇 |
2017年 | 17篇 |
2016年 | 23篇 |
2015年 | 13篇 |
2014年 | 25篇 |
2013年 | 41篇 |
2012年 | 36篇 |
2011年 | 32篇 |
2010年 | 13篇 |
2009年 | 23篇 |
2008年 | 42篇 |
2007年 | 35篇 |
2006年 | 39篇 |
2005年 | 35篇 |
2004年 | 43篇 |
2003年 | 31篇 |
2002年 | 24篇 |
2001年 | 24篇 |
2000年 | 15篇 |
1999年 | 8篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1965年 | 2篇 |
1964年 | 1篇 |
排序方式: 共有659条查询结果,搜索用时 31 毫秒
41.
The heritability of tolerance of wheat F3 lines to competition from annual ryegrass (Lolium rigidum), and its relationship to morphological traits, were determined using crosses between wheat cultivars with good and poor
competitive ability. Forty F2-derived F3 lines from a cross between two late flowering varieties (Machete × Spear) and 40 from a cross between early flowering varieties
(Wilgoyne × Gutha) were grown in the field with and without annual ryegrass. There was significant genetic variation between
lines within each of the two populations in a number of aspects of plant growth and development, including yield in monoculture.
The estimates of heritability for % yield loss due to competition were 0.25 and 0.57 in the two crosses respectively, indicating
that selection for high tolerance to competition in the F3 generation or later should be effective. Fairly strong relationships between height and % yield loss and between leaf length
and % yield loss suggest that these may be useful auxiliary traits when selecting for low % yield loss. However, differences
between crosses in the magnitude and sign of genetic and phenotypic correlation between traits indicate that competitive ability
is a complex character influenced by many factors.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
42.
Hoy-Taek Kim Yutaka Hirata Yong-Uk Shin Hae-Sung Hwang Jeong-Hwan Hwang Il-Sheob Shin Dae-Il Kim Sang-Jo Kang Hyun-Jung Kim Dong-Young Shin Ill-Sup Nou 《Euphytica》2004,138(1):73-80
The pear cultivar ‘Osa-Nijisseiki’ (S2Ssm
4; sm = stylar-part mutant) has been used as a parent to breed self-compatible cultivars that produce excellent fruits. However,
determination of the self-compatibility of ‘Osa-Nijisseiki’ offspring requires a lot of time, 6 years or more, by conventional
cross breeding. We have designed a rapid reliable method for the identification of self-compatible varieties of ‘Osa-Nijisseiki’
offspring based on the polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) with S-allele specific
restriction endonucleases. By using this method, 8 self-compatible varieties were selected among 16 selections resulting from
a cross between the self-compatible cultivar ‘Osa-Nijisseiki’ (S2Ssm
4) and the self-incompatible cultivars ‘Niitaka’ (S3S9), ‘Whasan’ (S3S5), ‘Chuwhangbae’ (S4S6). The S-genotypes of 16 ‘Osa-Nijisseiki’ offsprings were also determined.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
43.
Rensing SA Lang D Zimmer AD Terry A Salamov A Shapiro H Nishiyama T Perroud PF Lindquist EA Kamisugi Y Tanahashi T Sakakibara K Fujita T Oishi K Shin-I T Kuroki Y Toyoda A Suzuki Y Hashimoto S Yamaguchi K Sugano S Kohara Y Fujiyama A Anterola A Aoki S Ashton N Barbazuk WB Barker E Bennetzen JL Blankenship R Cho SH Dutcher SK Estelle M Fawcett JA Gundlach H Hanada K Heyl A Hicks KA Hughes J Lohr M Mayer K Melkozernov A Murata T Nelson DR Pils B Prigge M Reiss B Renner T Rombauts S Rushton PJ 《Science (New York, N.Y.)》2008,319(5859):64-69
We report the draft genome sequence of the model moss Physcomitrella patens and compare its features with those of flowering plants, from which it is separated by more than 400 million years, and unicellular aquatic algae. This comparison reveals genomic changes concomitant with the evolutionary movement to land, including a general increase in gene family complexity; loss of genes associated with aquatic environments (e.g., flagellar arms); acquisition of genes for tolerating terrestrial stresses (e.g., variation in temperature and water availability); and the development of the auxin and abscisic acid signaling pathways for coordinating multicellular growth and dehydration response. The Physcomitrella genome provides a resource for phylogenetic inferences about gene function and for experimental analysis of plant processes through this plant's unique facility for reverse genetics. 相似文献
44.
Rice Full-Length cDNA Consortium;National Institute of Agrobiological Sciences Rice Full-Length cDNA Project Team Kikuchi S Satoh K Nagata T Kawagashira N Doi K Kishimoto N Yazaki J Ishikawa M Yamada H Ooka H Hotta I Kojima K Namiki T Ohneda E Yahagi W Suzuki K Li CJ Ohtsuki K Shishiki T;Foundation of Advancement of International Science Genome Sequencing & Analysis Group Otomo Y Murakami K Iida Y Sugano S Fujimura T Suzuki Y Tsunoda Y Kurosaki T Kodama T Masuda H Kobayashi M Xie Q Lu M 《Science (New York, N.Y.)》2003,301(5631):376-379
45.
Oscillatory expression of the bHLH factor Hes1 regulated by a negative feedback loop 总被引:1,自引:0,他引:1
Hirata H Yoshiura S Ohtsuka T Bessho Y Harada T Yoshikawa K Kageyama R 《Science (New York, N.Y.)》2002,298(5594):840-843
46.
Excess cyclin E-Cdk2 accelerates entry into S phase of the cell cycle and promotes polyploidy, which may contribute to genomic instability in cancer cells. We identified 20 amino acids in cyclin E as a centrosomal localization signal (CLS) essential for both centrosomal targeting and promoting DNA synthesis. Expressed wild-type, but not mutant, CLS peptides localized on the centrosome, prevented endogenous cyclin E and cyclin A from localizing to the centrosome, and inhibited DNA synthesis. Ectopic cyclin E localized to the centrosome and accelerated S phase entry even with mutations that abolish Cdk2 binding, but not with a mutation in the CLS. These results suggest that cyclin E has a modular centrosomal-targeting domain essential for promoting S phase entry in a Cdk2-independent manner. 相似文献
47.
鲢及其加工废弃物发酵鱼露的比较 总被引:9,自引:0,他引:9
本研究分别以鲢全鱼及鲢鱼糜加工中的废弃物为原料发酵鱼露。测定了发酵过程中pH1T-VBN以及氨基酸的变化情况,分析了产品的理化成份并比较了氨基酸组成。结果表明,以鲢全鱼和废弃物发酵鱼露过程中pH、T-VBN以及氨基酸总量的变化情况基本相同。产品的感官评价结果无显著差异;全鱼发酵产品的氨基氮、总氮比由废弃物发酵的产品高,但是后者的氨基酸转化率、脂肪、红色指数以及呈鲜味的氨基酸占氨基酸总量的比例比前者高。 相似文献
48.
Many salmonids have become at risk of extinction. For teleosts whose eggs cannot be cryopreserved, developing techniques other than egg cryopreservation to save genetic resources is imperative. In this study, spermatogonia from rainbow trout were intraperitoneally transplanted into newly hatched sterile triploid masu salmon. Transplanted trout spermatogonia underwent spermatogenesis and oogenesis in male and female recipients, respectively. At 2 years after transplantation, triploid salmon recipients only produced trout sperm and eggs. With use of these salmon as parents, we successfully produced only donor-derived trout offspring. Thus, by transplanting cryopreserved spermatogonia into sterile xenogeneic recipients, we can generate individuals of a threatened species. 相似文献
49.
50.
采用系统采样和野外饲养的方法,同杨干透翅蛾幼虫有8个龄期,用零点标记法研究了幼虫的生长进度;同时通过野外取样调查,观察了不同年群幼虫间的演替过程。 相似文献