全文获取类型
收费全文 | 979篇 |
免费 | 61篇 |
国内免费 | 14篇 |
专业分类
林业 | 120篇 |
农学 | 29篇 |
基础科学 | 6篇 |
110篇 | |
综合类 | 123篇 |
农作物 | 54篇 |
水产渔业 | 85篇 |
畜牧兽医 | 449篇 |
园艺 | 24篇 |
植物保护 | 54篇 |
出版年
2024年 | 2篇 |
2022年 | 16篇 |
2021年 | 30篇 |
2020年 | 15篇 |
2019年 | 14篇 |
2018年 | 28篇 |
2017年 | 30篇 |
2016年 | 31篇 |
2015年 | 33篇 |
2014年 | 40篇 |
2013年 | 64篇 |
2012年 | 68篇 |
2011年 | 78篇 |
2010年 | 38篇 |
2009年 | 45篇 |
2008年 | 47篇 |
2007年 | 53篇 |
2006年 | 74篇 |
2005年 | 66篇 |
2004年 | 55篇 |
2003年 | 45篇 |
2002年 | 51篇 |
2001年 | 17篇 |
2000年 | 18篇 |
1999年 | 8篇 |
1998年 | 7篇 |
1997年 | 2篇 |
1996年 | 8篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1981年 | 5篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1971年 | 3篇 |
1970年 | 2篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有1054条查询结果,搜索用时 15 毫秒
91.
Ken‐ichi YAMANAKA Masahiro KANEDA Yasushi INABA Koji SAITO Kaiyu KUBOTA Miki SAKATANI Satoshi SUGIMURA Kei IMAI Shinya WATANABE Masashi TAKAHASHI 《Animal Science Journal》2011,82(4):523-530
Many observations have been made on cloned embryos and on adult clones by somatic cell nuclear transfer (SCNT), but it is still unclear whether the progeny of cloned animals is presenting normal epigenetic status. Here, in order to accumulate the information for evaluating the normality of cloned cattle, we analyzed the DNA methylation status on satellite I region in blastocysts obtained from cloned cattle. Embryos were produced by artificial insemination (AI) to non‐cloned or cloned dams using semen from non‐cloned or cloned sires. After 7 days of AI, embryos at blastocyst stage were collected by uterine flushing. The DNA methylation levels in embryos obtained by using semen and/or oocytes from cloned cattle were similar to those in in vivo embryos from non‐cloned cattle. In contrast, the DNA methylation levels in SCNT embryos were significantly higher (P < 0.01) than those in in vivo embryos from non‐cloned and cloned cattle, approximately similar to those in somatic cells used as donor cells. Thus, this study provides useful information that epigenetic status may be normal in the progeny of cloned cattle, suggesting the normality of germline cells in cloned cattle. 相似文献
92.
Pfeiffer DU Otte MJ Roland-Holst D Inui K Nguyen T Zilberman D 《Veterinary journal (London, England : 1997)》2011,(3):309-316
This paper analyses the publicly available data on the distribution and evolution of highly pathogenic avian influenza virus (HPAIV) H5N1 clades, whilst acknowledging the biases resulting from the non-random selection of isolates for gene sequencing. The data indicate molecular heterogeneity in the global distribution of HPAIV H5N1, in particular in different parts of East and Southeast Asia. Analysis of the temporal pattern of haemagglutinin clade data shows a progression from clade 0 (the ‘dominant’ clade between 1996 and 2002) to clade 1 (2003–2005) and then to clade 2.3.4 (2005 onwards). This process continuously produces variants, depending on the frequency of virus multiplication in the host population, which is influenced by geographical variation in poultry density, poultry production systems and also HPAI risk management measures such as vaccination. Increased multilateral collaboration needs to focus on developing enhanced disease surveillance and control targeted at evolutionary ‘hotspots’. 相似文献
93.
94.
Arthur J. Horowitz Ken R. Lum John R. Garbarino Gwendy E. M. Hall Claire Lemieux Charles R. Demas 《Water, air, and soil pollution》1996,90(1-2):281-294
The almost universally accepted operational definition for dissolved constituents is based on processing The almost universally accepted operational definition for dissolved constituents is based on processing whole-water samples through a 0.45-μm membrane filter. Results from field and laboratory experiments indicate that a number of factors associated with filtration, other than just pore size (e.g., diameter, manufacturer, volume of sample processed, amount of suspended sediment in the sample), can produce substantial variations in the ‘disolved’ concentrations of such elements as Fe, Al, Cu, Zn, Pb, Co, and Ni. These variations result from the inclusion/exclusion of colloidally-associated trace elements. Thus, 'dissolved' concentrations quantitated by analyzing filtrates generated by processing whole-water through similar pore-sized membrane filters may not be equal/comparable. As such, simple filtration through a 0.45-μm membrane filter may no longer represent an acceptable operational definition for dissolved chemical constituents. This conclusion may have important implications for environmental studies and regulatory agencies. 相似文献
95.
Food-drug interaction between ferulic acid and nateglinide involving the fluorescein/H+ cotransport system 总被引:2,自引:0,他引:2
Itagaki S Kobayashi Y Otsuka Y Kubo S Kobayashi M Hirano T Iseki K 《Journal of agricultural and food chemistry》2005,53(7):2499-2502
In clinical, patients usually take many kinds of drugs at the same time. Thus, drug-drug interactions involving transporters can often directly affect the therapeutic safety and efficacy of many drugs. However, there have been few studies on food-drug interactions involving transporters. Dietary polyphenols have been widely assumed to be beneficial to human health. Polyphenols are commercially prepared and used as functional foods. We report here for the first time that ferulic acid, which is widely used as a functional food, affects the transport of clinical agents. It is important to be aware of the potential of food-drug interactions and to act in order to prevent undesirable and harmful clinical consequences. 相似文献
96.
Kazuhiro Ujiie Toshio Yamamoto Masahiro Yano Ken Ishimaru 《Genetic Resources and Crop Evolution》2016,63(1):97-123
The yield of Koshihikari, a Japanese premium rice variety, is relatively lower than that of modern high yielding varieties. IR64 carries several well-known genes such as GS3, an important gene for grain size, sd-1, a semi-dwarf gene, and NARROW LEAF1 (NAL1), a gene for small, narrow flag leaves. In this study, we used two sets of chromosome segment substitution lines (CSSLs), from Koshihikari and IR64, and attempted to evaluate the genetic factors that cause differences between parents by analyzing the function of chromosome regions affecting a trait (CRATs). For 28 traits, we identified 312 CRATs in the Koshihikari background and 275 in the IR64 background. In these, donor alleles had positive effects in 84 and 103 CRATs, respectively. Among these, the CRAT related to GS3 and those for grain number expanded the potential sink size in Koshihikari, although this did not affect final yield. The combination of CRATs that enhances source ability may increase grain yield. Although the sd-1 gene might improve resistance to lodging, the yield of CSSLs with sd-1 decreased by 28.7 %. These results suggest that the smaller biomass conferred by sd-1 might reduce canopy photosynthesis. In the Koshihikari background, the CRAT related to NAL1 and those located on chr. 6 increased SPAD value but had the opposite effect on leaf size. Two CRATs that were detected on chr. 6 and 7 increased leaf area without any effect on the SPAD value. The combination of these CRATs for area and SPAD value might improve source ability. 相似文献
97.
云南东方蜜蜂形态特征与环境因子相关性的研究 总被引:4,自引:0,他引:4
云南东方蜜蜂种群内遗传变异丰富 ,每个形态性状特征均具有丰富的多态性 ,种群间具多型性 ,且种群中许多形态性状特征表现出较明显的地理变异性[1~ 3 ] 。从滇南 -滇中 -滇西北 ,随纬度或海拔的增加 ,形态特征变异的总趋势是 :蜜蜂个体增大、体色变深。具体是 :1.前翅长、宽 ,背板 3、 4宽 ;2 .后腿长 ,蜡镜长、宽 ,蜡镜间距 ,腹片 3、 6的长和宽逐渐增加 ;3.背板 3、 4的色素度 ,小盾片的色素度逐渐加深。云南东方蜜蜂种群形态性状的多态性、多型性及其生态地理变异式样 ,均具有生态适应意义 :与云南东方蜜蜂分布区的气候特点相适应 ,而且还与海拔高度和纬度的变化有着密切的适应关系 相似文献
98.
99.
100.
Porcine alpha-fetoprotein (AFP) was purified from the sera of four-day-old piglets using an immunoadsorbent column. The molecular weight of the AFP was 80,000 when determined by gel filtration on Sephadex G-200 and 75,000 when determined by sodium dodecylsulphate polyacrylamide gel electrophoresis. The isoelectric point of the AFP was pH 4.85 at 0 degree C. The maximum concentration of serum AFP was reached on the fourth day after birth (mean value 1.1 mg ml-1), and it then decreased to 10 micrograms ml-1 when the piglets were 35 days old. The concentration of serum albumin increased rapidly between birth and seven days old, reaching 16 to 17 mg ml-1 at seven days old. Between birth and seven days old, the serum concentrations of AFP and albumin were approximately inversely proportional. 相似文献