全文获取类型
收费全文 | 409篇 |
免费 | 14篇 |
国内免费 | 1篇 |
专业分类
林业 | 37篇 |
农学 | 12篇 |
基础科学 | 3篇 |
47篇 | |
综合类 | 20篇 |
农作物 | 6篇 |
水产渔业 | 88篇 |
畜牧兽医 | 184篇 |
园艺 | 5篇 |
植物保护 | 22篇 |
出版年
2022年 | 5篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 6篇 |
2014年 | 18篇 |
2013年 | 30篇 |
2012年 | 30篇 |
2011年 | 31篇 |
2010年 | 12篇 |
2009年 | 13篇 |
2008年 | 28篇 |
2007年 | 28篇 |
2006年 | 36篇 |
2005年 | 28篇 |
2004年 | 21篇 |
2003年 | 21篇 |
2002年 | 8篇 |
2001年 | 20篇 |
2000年 | 18篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 3篇 |
1991年 | 9篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1978年 | 2篇 |
1974年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有424条查询结果,搜索用时 0 毫秒
421.
The development of a coupled model (PCPF-SWMS) to simulate water flow and pollutant transport in Japanese paddy fields 总被引:1,自引:0,他引:1
Julien Tournebize Hirozumi Watanabe Kazuhiro Takagi Taku Nishimura 《Paddy and Water Environment》2006,4(1):39-51
A new coupled model (PCPF–SWMS) was developed for simulating fate and behavior of pollutant in paddy water and paddy soil.
The model coupled the PCPF-1, a lumped model simulating pesticide concentrations in paddy water and 1 cm-surface sediment
compartment, and the SWMS-2D, a finite element numerical model solving Richard's and advection-dispersion equations for solute
transport in soil compartment. The coupling involved improvements on interactions of the water flow and the concentration
the pollutant of at the soil interface between both compartments. The monitoring data collected from experimental plots in
Tsukuba, Japan in 1998 and 1999 were used to parameterise and calibrate hydraulic functioning, hydrodynamic and hydrodispersive
parameters of the paddy soil. The analysis on the hydraulic functioning of paddy soil revealed that the hard pan layer was
the key factor controlling percolation rate and tracer transport. Matric potential and tracer monitoring highlighted the evolution
of saturated hydraulic conductivity (K
S) of hard pan layer during the crop season. K
S slightly decreased after puddling by clay clogging and strongly increased after mid term drainage by drying cracks. The model
was able to calculate residential time in every soil layers. Residential time of tracer in top saturated layers was evaluated
to be less than 40 days. It took 60 days to reach the unsaturated layers below hardpan layer. 相似文献
422.
Mitochondrial DNA variation and population structure of the Japanese mitten crab Eriocheir japonica 总被引:2,自引:0,他引:2
Izumi Yamasaki Goro Yoshizaki Masashi Yokota Carlos A. Strüssmann Seiichi Watanabe 《Fisheries Science》2006,72(2):299-309
ABSTRACT: The Japanese mitten crab Eriocheir japonica is a common grapsid species found throughout freshwater and estuarine regions in Japan. In order to obtain information on the genetic variation and population structure of this species, a polymerase chain reaction (PCR) restriction fragment length polymorphism (RFLP) analysis was conducted on the cytochrome oxidase subunit I (COI) of mitochondrial DNA, on 666 individuals from 19 sample sites covering the three main geographic regions of Japan (Main Islands, Okinawa, and Ogasawara). Genetic analysis using seven restriction enzymes produced an array of 61 composite haplotypes. Three regional groups corresponding to the three geographic regions were clearly identified by cluster and molecular variance model ( amova ) analyses. Each of the three groups showed dominant haplotypes that were almost completely absent in populations from the other geographic areas. Comparison with published information for other species indicates that the degree of genetic divergence between these three main groups is equivalent to the genetic distance between congeneric species. Thus, the population structure of the Japanese mitten crab, as inferred from mtDNA analysis, is formed by genetically distinct groups that closely reflect their geographic distribution in the Japanese archipelago as well as restricted gene flow. 相似文献
423.
The Japanese population of the cyprinid minnow Aphyocypris chinensis is nearing extinction in the wild. The genetic diversity of three microsatellite loci in five captive populations was investigated,
and an effective breeding strategy to reduce inbreeding from pairwise relatedness (R
xy
) between each captive line is discussed. The average number of alleles ranged 2.33–4.67 and the average heterozygosity ranged
0.283–0.602. The pairwise relatedness observed in most combinations showed a significant decrease between the populations.
It is suggested that exchange of individuals between different breeding lines should effectively stop inbreeding. Studies
show that the effective population size (N
e
) estimated from the number of parental individuals was 8.54 in one captive population, which is insufficient to maintain
genetic diversity. It is recommended that more parental individuals should be used, and to exchange fish in a rotating mating
mode between institutions participating in captive breeding of A. chinensis. 相似文献
424.
Ryuichi Haginoya Kunio Sakai Takashi Komatsu Seiichi Nagao Kenji Yokoyama Toshifumi Takeuchi Ritsuko Matsukawa Isao Karube 《Cereal Chemistry》1997,74(6):745-749
The determination of damaged starch and diastatic activity in flour was studied using a flow-injection analysis (FIA) biosensor system. The system consisted of an oxygen electrode and an immobilized enzyme column containing purified glucoamylase and glucose oxidase immobilized on activated aminopropyl glass beads. The biosensor system has an optimum pH between 6.5 and 7.5 and an optimum temperature of 35°C for glucose measurement. The response of the FIA biosensor was linear up to 1.000 g/L of glucose with a lower detection limit of 0.025 g/L. Each assay took about 20 min, and the system showed good reproducibility (r = 0.998, n = 8). When applied to the measurement of damaged starch and diastatic activity in wheat flour, the results obtained agreed with those obtained using the conventional methods of measurement. This biosensor system is a rapid practical alternative for the measurement of damaged starch and diastatic activity in wheat flour. 相似文献