全文获取类型
收费全文 | 1271篇 |
免费 | 60篇 |
国内免费 | 6篇 |
专业分类
林业 | 62篇 |
农学 | 62篇 |
基础科学 | 2篇 |
164篇 | |
综合类 | 64篇 |
农作物 | 38篇 |
水产渔业 | 96篇 |
畜牧兽医 | 763篇 |
园艺 | 11篇 |
植物保护 | 75篇 |
出版年
2021年 | 21篇 |
2020年 | 19篇 |
2019年 | 23篇 |
2018年 | 23篇 |
2017年 | 36篇 |
2016年 | 34篇 |
2015年 | 37篇 |
2014年 | 43篇 |
2013年 | 91篇 |
2012年 | 78篇 |
2011年 | 80篇 |
2010年 | 29篇 |
2009年 | 37篇 |
2008年 | 56篇 |
2007年 | 58篇 |
2006年 | 76篇 |
2005年 | 79篇 |
2004年 | 64篇 |
2003年 | 59篇 |
2002年 | 32篇 |
2001年 | 43篇 |
2000年 | 50篇 |
1999年 | 41篇 |
1998年 | 6篇 |
1997年 | 10篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1992年 | 14篇 |
1991年 | 15篇 |
1990年 | 16篇 |
1989年 | 15篇 |
1988年 | 16篇 |
1987年 | 18篇 |
1986年 | 9篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1979年 | 9篇 |
1977年 | 7篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1972年 | 7篇 |
1970年 | 3篇 |
1968年 | 3篇 |
1967年 | 3篇 |
1966年 | 3篇 |
1965年 | 3篇 |
排序方式: 共有1337条查询结果,搜索用时 15 毫秒
41.
Identification of Mulberry Dwarf Phytoplasmas in the Genital Organs and Eggs of Leafhopper Hishimonoides sellatiformis 总被引:1,自引:0,他引:1
ABSTRACT The presence of mulberry dwarf (MD) phytoplasmas in organs of the inoculative vector insects Hishimonoides sellatiformis and Hishimonus sellatus was determined by means of electron microscopy (EM) and polymerase chain reaction (PCR) assays. Many MD phytoplasmas were detected in genital organs as well as in the intestines, salivary glands, brains, fat bodies, and thoracic ganglia of Hishimonoides sellatiformis, but only in the intestine and salivary glands of Hishimonus sellatus. Many phytoplasmas with characteristic morphology were observed via EM in ovaries, seminal receptacles, and testes, and they were further identified by PCR assays with group I-specific primers. In addition, the organisms were detected by direct or nested PCR assays in eggs (head pigmentation stage of embryos) laid on mulberry shoots by inoculative leafhoppers and in the newly hatched nymphs from these eggs. These findings indicate that transovarial transmission of MD phytoplasmas occurs in Hishimonoides sellatiformis. 相似文献
42.
The aim of the present study was to determine the whole nucleotide sequence of the open reading frame of the sex‐determining region Y (SRY‐ORF) in wild sika deer. The SRY gene of wild sika deer was obtained by polymerase chain reaction (PCR) with DNA from blood samples. The whole nucleotide sequence of the SRY‐ORF in wild sika deer consisted of 687 bp and encoded 229 deduced amino acids. In comparison with the bovine SRY gene, the percentage of nucleotide sequence homology was 91.0% in the overall ORF, and those of the N‐terminal, high mobility group (HMG) box, and C‐terminal regions within ORF were 88.9%, 96.2% and 87.9%, respectively. The nucleotide sequences of sika deer SRY‐ORF characterized in the present study can be used for phylogenetic analysis or sexing in wild sika deer. 相似文献
43.
ABSTRACT Previous work suggested that the efe gene encoding the ethylene-forming enzyme was present in the plasmids of three pathovars of Pseudomonas syringae including glycinea, phaseolicola (kudzu strains), and cannabina. However, no direct evidence to support this assumption had been presented. In the current study, we isolated the conjugative plasmid harboring the efe gene (ethylene plasmid) designated pETH2 from P. syringae pv. glycinea MAFF301683. pETH2 was detected by Southern blot hybridization using the efe probe, marked with the transposon mini-Tn5-Km1, and transferred into P. syringae Ni27(n), which does not produce ethylene. The transconjugant Ni27(n) (pETH2) produced ethylene at a level similar to pv. glycinea MAFF301683. In addition, the plasmid designated pCOR2, which encodes coronatine biosynthesis genes, was detected in the same strain. Although the molecular size of the plasmid pCOR2 was not easily distinguishable from pETH2, pCOR2 transferred independently into Ni27(n) and the transconjugants produced coronatine. These findings suggested that the efe gene has been horizontally dispersed among pathovars of P. syringae by plasmid-mediated conjugation in nature. 相似文献
44.
M. Nagai M. Sato H. Nagano H. Pang X. Kong T. Murakami T. Ozawa H. Akashi 《Veterinary microbiology》1998,60(2-4):271-276
Cytopathogenic and non-cytopathogenic bovine viral diarrhea viruses (BVDVs) were isolated from cattle with mucosal disease or persistent infection in Japan. These isolates were compared for antigenic properties by cross-neutralization tests with Japanese reference strains of BVDV belonging to classical type 1. Significantly low cross-reactivity to reference strains was noted, indicating the viruses to possibly represent a new serotype in Japan. Thus, to determine the genotype of the isolates, nucleotide sequences of the 5′ untranslated region were determined and compared with those of previously reported BVDV 1 and 2. The isolates were clearly shown to belong to BVDV 2, not to BVDV 1. 相似文献
45.
46.
47.
48.
49.
Jie Liu Rumi Fujita Michiko Sato Kuniyoshi Shimizu Fumiko Konishi Kiyoshi Noda Shoichiro Kumamoto Chie Ueda Hisatoshi Tajiri Shuhei Kaneko Yoshitaro Suimi Ryuichiro Kondo 《Journal of Wood Science》2005,51(2):189-192
The inhibitory effects of 102 methanol extracts of 40 mycelia, 9 culture fluids, and 53 fruiting bodies of 40 strains of Ganoderma lucidum on 5-reductase were investigated. The methanol extract of the fruiting body of each strain was found to show the strongest 5-reductase inhibitory activity among the extracts tested. 相似文献
50.
Self-bonding is the main factor of the performance expression of binderless boards, and therefore its clarification is considered
to be an important issue. For this purpose, a series of chemical analyses were conducted on kenaf core binderless boards and
their chemical changes during the hot-pressing process are discussed in this article. First of all, binderless boards were
prepared from kenaf core powder at different pressing temperatures (without steam-explosion process) and were used for chemical
analyses after they were reduced into powders and extracted with methanol. To investigate their chemical changes, lignin,
holocellulose, and neutral sugar contents were determined, Fourier transform infrared (FTIR) spectra were recorded, and the
nitrobenzene oxidation procedure was applied. As a result, it was found that parts of lignin and hemicelullose were decomposed
during the hot-pressing process; however, the contribution of the resulting fractions to selfbonding was not observed. In
addition, progress of condensation reactions in lignin and the formation of chemical bonds by low molecular weight conjugated
carbonyl compounds in methanol extractives were observed. Thermal softening of lignin is also suggested to play an important
role in the expression of board performance. 相似文献