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排序方式: 共有106条查询结果,搜索用时 16 毫秒
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Geoffrey R. Tick Colleen M. McColl Irfan Yolcubal Mark L. Brusseau 《Water, air, and soil pollution》2007,184(1-4):355-362
Robust measurements of porous-medium tortuosity are one of the many components needed for accurate characterization and prediction of fluid flow and contaminant transport in the subsurface. A gas-phase diffusive tracer-test method is evaluated for the in-situ measurement of tortuosity in the vadose zone. This technique presents an alternative to employing widely-used correlations to estimate tortuosity. A small-scale field study was conducted using a single well and a non-reactive gas-phase tracer (sulfur hexafluoride; SF6). Gas samples were collected from the injection point periodically after tracer injection into the soil matrix. An effective radius of influence of 50 cm was determined for the tests. An analytical solution was calibrated to the measured temporal concentration distribution, producing a fitted value for tortuosity. The value obtained from the tracer tests was compared to values estimated with several widely-used correlations. The value obtained from the tracer tests was generally larger than the values estimated with the correlations, which spanned a relatively wide range. The tracer-test method provides a means by which to determine in-situ measurements of tortuosity, allowing for better characterization of contaminant transport in the vadose zone. 相似文献
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This experiment was carried out to determine the effects of using L-carnitine and humate alone or in combination in quail diets on laying performance, egg traits and blood parameters. A total of 280 Japanese quails aged 10 weeks, divided into one control group and three treatment groups, were used. The diets of the first, second and third treatment groups were supplemented with 100 mg L-carnitine/kg, 1.5 g humate (Farmagülat?r Dry Plus)/kg and 100 mg L-camitine + 1.5 g humate/kg, respectively. The experimental period lasted 16 weeks. The addition of L-carnitine and sodium humate alone or in combination did not significantly affect body weight, feed consumption, egg production, feed conversion ratio, mortality, egg-shell thickness, egg yolk index and the percentages of egg-shell, albumen and yolk. Egg weight increased (P < 0.001) with L-carnitine supplementation. The values of egg albumen height (P < 0.05), egg albumen index (P < 0.01) and egg Haugh unit (P < 0.05) were increased with humate supplementation. Egg cholesterol content and blood serum parameters were not affected by the supplementation of L-carnitine with or without humate. The results in this study demonstrated that L-carnitine supplementation increased egg weight while humate addition increased egg albumen index and egg Haugh unit of laying quails. However, the combined administration of L-carnitine and humate did not have any significant effects on the parameters measured. 相似文献
5.
ABSTRACT Resistance to Soybean mosaic virus (SMV) was identified in PI 88788 soybean, a germ plasm accession from China that is used widely as a source of resistance to soybean cyst nematode. Strains SMV-G1 through -G7 infected the inoculated leaves of PI 88788 but were not detected in upper, noninoculated trifoliolate leaves. Inheritance of resistance was determined by inoculating progenies of crosses of PI 88788 with susceptible cvs. Essex and Lee 68 with SMV strains G1 and G7. Allelomorphic relationships with known genes for resistance to SMV were tested in crosses with the resistant genotypes PI 96983, L29, and V94-5152, possessing Rsv1, Rsv3, and Rsv4 genes, respectively. Data analyses showed that resistance in PI 88788 to SMV-G1 is controlled by a single, partially dominant gene; however, to SMV-G7, the same gene was completely dominant. The PI 88788 gene was independent of the Rsv1 and Rsv3 loci, but allelic to Rsv4 in V94-5152. Expression of the Rsv4 gene in PI 88788 resulted in a reduced number of infection sites and restricted short- and long-distance movement of virus, rather than hypersensitivity. A unique late susceptible phenotype was strongly associated with heterozygosity. This gene has potential value for use in gene pyramiding to achieve resistance to several SMV strains, as well as for rate-reducing resistance. 相似文献
6.
Theories about sexual selection can be traced back to Darwin in 1871. He proposed that males fertilize as many females as possible with inexpensive sperm, whereas females, with a limited supply of large eggs, select the genetically highest quality males to endow their offspring with superior capabilities. Since its proposal, problems with this narrative have continued to accumulate, and it is our view that sexual selection theory needs to be replaced. We suggest an approach that relies on the exchange of direct ecological benefits among cooperating animals without reference to genetic benefits. This approach can be expressed mathematically in a branch of game theory that pertains to bargaining and side payments. 相似文献
7.
Alkuraya FS Saadi I Lund JJ Turbe-Doan A Morton CC Maas RL 《Science (New York, N.Y.)》2006,313(5794):1751
The posttranslational modification sumoylation can have multiple effects on its substrate proteins. We studied a patient with isolated cleft lip and palate and a balanced chromosomal translocation that disrupts the SUMO1 (small ubiquitin-related modifier) gene, resulting in haploinsufficiency. In mouse, we found that Sumo1 is expressed in the developing lip and palate and that a Sumo1 hypomorphic allele manifests an incompletely penetrant orofacial clefting phenotype. Products of several genes implicated in clefting are sumoylated, and the Sumo1 hypomorphic allele interacts genetically with a loss-of-function allele for one of these loci. Thus, sumoylation defines a network of genes important for palatogenesis. 相似文献
8.
Awais MM Akhtar M Iqbal Z Muhammad F Anwar MI 《Tropical animal health and production》2012,44(2):323-328
The present paper reports the prevalence of coccidiosis in industrial broiler chickens in Faisalabad, Punjab, Pakistan to
determine the occurrence of different species of Eimeria in the area and to assess their correlation with the environmental conditions including temperature, humidity and rainfall.
The study was conducted from January 2009 to December 2010. Examination of chicken guts revealed 43.89% (n = 3,283/7,480) prevalence of coccidiosis. The highest prevalence (27.04%) was recorded of Eimeria tenella followed by Eimeria maxima (22.42%), Eimeria acervulina (19.89%) and Eimeria necatrix (4.02%). The prevalence of disease was significantly higher (P < 0.05) in autumn (60.02 ± 4.38) followed by summer (47.42 ± 2.92), spring (36.92 ± 2.27) and winter (29.89 ± 3.43). Likewise,
prevalence of different species of Eimeria also varied (P < 0.05) in different seasons of the year except that of E. necatrix. A strong correlation (P < 0.05) of environmental conditions with the overall and species-wise prevalence of coccidiosis was recorded except E. necatrix. 相似文献
9.
Irfan Ahmad MIR Bablu KUMAR Anil TAKU Farah FARIDI Mohd. Altaf BHAT Naseer Ahmad BABA Tahir MAQBOOL 《Journal of Equine Science》2013,24(3):53-55
Present study was undertaken to study the prevalence of β-haemolytic streptococci in
equine of northern temperate region of Jammu and Kashmir, India. One hundred and forty one
samples were collected in duplicate from nasopharyngeal tract of diseased (53) and
apparently healthy equine (88) for isolation and direct PCR. A total of 77 isolates of
streptococci were recovered from 141 samples with an overall prevalence rate of 54.60%.
Out of these 77 isolates, 52 were from diseased and 25 from apparently healthy animals. Of
the 77 isolates, 4 were identified as Streptococcus equi subsp.
equi, 56 as S. equi subsp.
zooepidemicus and 17 as S. dysgalactiae subsp.
equisimilis. Thus the overall prevalence of S. equi subsp.
equi, S. equi subsp. zooepidemicus
and S. dysgalactiae subsp. equisimilis was 2.83, 39.71
and 12.05% respectively. The sensitivity of the PCR for the detection of S.
equi species was found higher when attempted from direct swab samples. 相似文献
10.
Muhammad MUSHTAQ Iftikhar HUSSAIN Afsar MIAN Shahid MUNIR Irfan AHMED Abdul Aziz KHAN 《Integrative zoology》2013,8(3):285-292
This research study evaluated the effect of different additives on the bait consumption by Indian crested porcupine, a serious forest and agricultural pest, under field conditions. Different additives (saccharin, common salt, bone meal, fish meal, peanut butter, egg yolk, egg shell powder, yeast powder, mineral oil and coconut oil) at 2 and 5% each were tested for their relative preference, using groundnut–maize (1:1) as basic bait. All the additives were tested under a no‐choice test pattern. For control tests, no additive was mixed with the basic bait. Saccharin at 5% concentration significantly enhanced the consumption of bait over the basic bait, while 2% saccharin supplemented bait resulted in a non‐significant bait consumption. All other additives did not enhance the consumption of the bait material; rather, these worked as repellents. However, the repellency was lowest with the common salt, followed by egg yolk, egg shell powder, bone meal, peanut butter, mineral oil, fish meal and yeast powder, while coconut remained the most repellent compound. The present study suggested that groundnut–maize (1:1) supplemented with 5% saccharin was the preferred bait combination, and can be used with different rodenticides for the management of Indian crested porcupine. 相似文献