全文获取类型
收费全文 | 461篇 |
免费 | 35篇 |
专业分类
林业 | 68篇 |
农学 | 11篇 |
基础科学 | 1篇 |
46篇 | |
综合类 | 25篇 |
农作物 | 13篇 |
水产渔业 | 76篇 |
畜牧兽医 | 234篇 |
园艺 | 2篇 |
植物保护 | 20篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 2篇 |
2019年 | 10篇 |
2018年 | 17篇 |
2017年 | 14篇 |
2016年 | 13篇 |
2015年 | 13篇 |
2014年 | 15篇 |
2013年 | 25篇 |
2012年 | 16篇 |
2011年 | 30篇 |
2010年 | 13篇 |
2009年 | 21篇 |
2008年 | 34篇 |
2007年 | 27篇 |
2006年 | 29篇 |
2005年 | 27篇 |
2004年 | 19篇 |
2003年 | 41篇 |
2002年 | 22篇 |
2001年 | 24篇 |
2000年 | 17篇 |
1999年 | 16篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1979年 | 3篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有496条查询结果,搜索用时 15 毫秒
31.
Immunostimulant effects of nucleotide isolated from yeast RNA on carp, Cyprinus carpio L. 总被引:2,自引:0,他引:2
Nucleotides from yeast RNA were evaluated for their ability to enhance the non-specific immune responses in carp, Cyprinus carpio . Oral administration of nucleotides to fish daily for 3 days resulted in enhanced responses of phagocytic and nitroblue tetrazolium (NBT) activities in kidney phagocytic cells. This activation of kidney cells was observed for at least 10 days post-treatment. The serum complement and lysozyme activities also increased in fish treated with nucleotides. Furthermore, the number of Aeromonas hydrophila in nucleotide-treated fish significantly decreased in the blood, kidney and liver after intraperitoneal injection. Thus yeast nucleotides appear to enhance non-specific immune responses in fish. 相似文献
32.
Manuel Martin‐Flores Daniel M Sakai Luis Campoy RD Gleed 《Veterinary anaesthesia and analgesia》2014,41(3):269-277
ObjectiveTo evaluate if return of spontaneous ventilation to pre-relaxation values indicates complete recovery from neuromuscular blockade.Study designProspective, with each individual acting as its own control.AnimalsTen healthy adult female Beagle dogs weighing 6.2–9.4 kg.MethodsDogs were anesthetized with propofol, dexemedetomidine and isoflurane. Spontaneous ventilation was assessed by measuring end-tidal CO2, expired tidal volume, peak inspiratory flow, respiratory rate and minute ventilation. Vecuronium 25 μg kg?1 IV was administered and neuromuscular block was evaluated by measuring the train-of-four (TOF) ratio with acceleromyography in the hind limb. During spontaneous recovery from neuromuscular block, the TOF ratio when each ventilatory variable returned to baseline was recorded.ResultsThis dose of vecuronium produced moderate neuromuscular block in all dogs, with TOF ratio values of 0–18% at maximal block. Expired tidal volume, peak inspiratory flow and minute ventilation returned to pre-relaxation values when the median TOF ratio was ≤ 20%. The median TOF ratio was 42% when the end-tidal CO2 returned to pre-relaxation values.Conclusions and clinical relevanceSignificant residual neuromuscular block could be measured at the hind limb with acceleromyography when ventilation had spontaneously returned to pre-vecuronium values. Monitoring spontaneous ventilation, including end-tidal CO2, expired tidal volume, peak inspiratory flow or minute ventilation cannot be used as a surrogate for objective neuromuscular monitoring, and this practice may increase the risk of postoperative residual paralysis. 相似文献
33.
The siderophore avaroferrin (1), an inhibitor of Vibrio swarming that was recently identified in Shewanella algae B516, was produced by heterologous expression of the biosynthetic gene cluster cloned from a deep-sea sediment metagenomic DNA, together with two analogues, bisucaberin (2) and putrebactin (3). Avaroferrin (1) is a macrocyclic heterodimer of N-hydroxy-N-succinyl cadaverine (4) and N-hydroxy-N-succinyl-putrescine (5), whereas analogues 2 and 3 are homodimers of 4 and 5, respectively. Heterologous expression of two other related genes from culturable marine bacteria resulted in production of compounds 1–3, but in quite different proportions compared with production through expression of the metagenomic DNA. 相似文献
34.
Mizuho Sakai Sei-Ichi Okumura Kanami Onuma Hiroaki Senbokuya Kunio Yamamori 《Fisheries Science》2007,73(1):77-80
The telomere sequence type (TTAGGG)n is known to be distributed in various phyla in the Animalia and in Mastigophora (Protista). However, the telomere type of
Porifera (sponges), a phylum comprising the lowest multicellular animals, has not been reported. In this study, we examined
the three sponge species Leucetta chagosensis, Halichondria japonica, and Halichondria panicea for the presence of the telomere type (TTAGGG)n by fluorescence in situ hybridization (FISH). The oligonucleotide probe (TTAGGG)7 clearly displayed signals on the interphase nuclei of all three sponges. In contrast, the (TTAGG)7 probe, which has one base fewer than (TTAGGG)7, did not display the signals. These results suggest that the telomeres of the three sponges consist of (TTAGGG)n, which is identical to the sequence type found in many higher multicellular animals and in Mastigophora. Additionally, this
is the first study to reveal a telomere sequence type for Porifera. Moreover, these results suggest that Porifera are phylogenetically
related to Mastigophora, and supports the general theory that Porifera evolved from Mastigophora. Further, this study strongly
suggests that the origin of the (TTAGGG)n telomere sequence is to be found in a common ancestor of either the Bilateria and Porifera, or the Protista. 相似文献
35.
T Sakai K Takahashi S Hisasue M Horimoto T Takizawa 《Nippon juigaku zasshi. The Japanese journal of veterinary science》1990,52(1):121-127
From 1982 to 1987 a total of 4,371 dairy cattle in Saitama Prefecture, were examined for levels of hemagglutination inhibition (HI) antibody to Japanese encephalitis virus (JEV) and the correlation with meteorological factors and an antibody positive rate was studied. Positivity rates of HI antibody from July to October each year (Yi) ranged from 58.8 to 88.0% with a considerable annual variation. Simple regression analysis of Yi with the comparative meteorological value (Xi) was determined from mean temperatures (Ti, j-1), rainfalls (Ri, j-1) for 10-day-periods each, and the number of days showing 25 degrees C or above (ti, j-1) from June to September, which yielded a correlation coefficient of 0.8147 (p less than 0.05) and an equation for estimated HI antibody positivity rate: Yi = -0.04Xi+79.9 (p less than 0.05). Multiple regression analysis with the power values of three meteorological parameters as independent variables and Yi as the dependent variable, showed a multiple correlation coefficient of 0.987 (p less than 0.05) and a multiple regression equation: Yi = -3991T1/13-0.0035R-12+1978t1/9+4187 (p less than 0.05), giving estimated positivity rates almost equal to the values from the observations. Therefore, a predictive equation was formulated reflecting positive and negative correlations of sero-positivity with the temperature and the precipitation, respectively. 相似文献
36.
37.
A 49-kilodalton phosphoprotein in the Drosophila photoreceptor is an arrestin homolog 总被引:10,自引:0,他引:10
T Yamada Y Takeuchi N Komori H Kobayashi Y Sakai Y Hotta H Matsumoto 《Science (New York, N.Y.)》1990,248(4954):483-486
The gene encoding the 49-kilodalton protein that undergoes light-induced phosphorylation in the Drosophila photoreceptor has been isolated and characterized. The encoded protein has 401 amino acid residues and a molecular mass of 44,972 daltons, and it shares approximately 42 percent amino acid sequence identity with arrestin (S-antigen), which has been proposed to quench the light-induced cascade of guanosine 3',5'-monophosphate hydrolysis in vertebrate photoreceptors. Unlike the 49-kilodalton protein, however, arrestin, which appears to bind to phosphorylated rhodopsin, has not itself been reported to undergo phosphorylation. In vitro, Ca2+ was the only agent found that would stimulate the phosphorylation of the 49-kilodalton protein. The phosphorylation of this arrestin-like protein in vivo may therefore be triggered by a Ca2+ signal that is likely to be regulated by light-activated phosphoinositide-specific phospholipase C. 相似文献
38.
Iran supports five different vegetation zones. One of those is the Irano-Touranian zone that is located in the northeast of
Iran. This vegetation zone includes arid and semi-arid lands, and its area is about 3.5 million hm2. It supports growth of pistachio (Pistacia vera), a deciduous-broadleaved species, which is one of the ecologically and economically most important native species. In this
study, we analyzed three images acquired by ALOS satellite, including 10m resolution multispectral band (AVNIR-2), 2.5 m resolution
“Backward” PRISM image, and 2.5 m resolution “Nadir” PRISM image, based on a provided rational polynomial coefficient (RPC).
Using the “Backward” and “Nadir” images, a 2.5 m resolution digital elevation model (DEM) was produced. Four methods with
AVNIR-2 and PRISM data were used to produce pan-sharpening images and conduct an object-based feature extraction process.
Normalized Difference Vegetation Index (NDVI) was used to determine the maximum distribution of pistachio in related elevation.
The accuracy of the DEM was tested on 28 ground control points in the pair image as tie points, with the value of parallax
error of 0.9027 m. The created elevation map indicated that pistachio trees grow up at 650m above sea level (a.s.l.). The
result from NDVI in the related elevation showed the maximum density of pistachio at 800m a.s.l. In addition, the result of
feature extraction in the forest showed the area of each target element calculated. The results of this research will improve
decision-making and lead to sustainable management in general. 相似文献
39.
Linkage groups of a culicine mosquito, Culex tritaeniorhynchus, have been assigned to their respective chromosomes by genetic and cytologic observations of radiation-induced aberrations. Linkage group I is assigned to the smallest chromosome, linkage group II to the submetacentric chromosome, and linkage group III to the metacentric chromosome. 相似文献
40.
The membrane rotor ring from the vacuolar-type (V-type) sodium ion-pumping adenosine triphosphatase (Na+-ATPase) from Enterococcus hirae consists of 10 NtpK subunits, which are homologs of the 16-kilodalton and 8-kilodalton proteolipids found in other V-ATPases and in F1Fo- or F-ATPases, respectively. Each NtpK subunit has four transmembrane alpha helices, with a sodium ion bound between helices 2 and 4 at a site buried deeply in the membrane that includes the essential residue glutamate-139. This site is probably connected to the membrane surface by two half-channels in subunit NtpI, against which the ring rotates. Symmetry mismatch between the rotor and catalytic domains appears to be an intrinsic feature of both V- and F-ATPases. 相似文献