全文获取类型
收费全文 | 92篇 |
免费 | 14篇 |
国内免费 | 3篇 |
专业分类
林业 | 5篇 |
1篇 | |
综合类 | 18篇 |
畜牧兽医 | 83篇 |
园艺 | 1篇 |
植物保护 | 1篇 |
出版年
2023年 | 2篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 7篇 |
2016年 | 1篇 |
2015年 | 4篇 |
2014年 | 7篇 |
2013年 | 11篇 |
2012年 | 1篇 |
2011年 | 1篇 |
2010年 | 4篇 |
2009年 | 5篇 |
2008年 | 3篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 4篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1989年 | 1篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1979年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1933年 | 1篇 |
1901年 | 1篇 |
排序方式: 共有109条查询结果,搜索用时 15 毫秒
81.
82.
DK Keefer SD deFrance ME Moseley JB Richardson DR Satterlee A Day-Lewis 《Science (New York, N.Y.)》1998,281(5384):1833-1835
The archaeological site of Quebrada Tacahuay, Peru, dates to 12,700 to 12,500 calibrated years before the present (10,770 to 10,530 carbon-14 years before the present). It contains some of the oldest evidence of maritime-based economic activity in the New World. Recovered materials include a hearth, lithic cutting tools and flakes, and abundant processed marine fauna, primarily seabirds and fish. Sediments below and above the occupation layer were probably generated by El Nino events, indicating that El Nino was active during the Pleistocene as well as during the early and middle Holocene. 相似文献
83.
84.
85.
AIM: To gather information on the repeatability of a faecal nematode egg count (FEC) reduction (FECR) test (FECRT), evaluating both different methods of calculating efficacy and variations within a method, in order to supply veterinarians and other advisors with sufficient information to apply some level of confidence around a diagnosis of anthelmintic resistance based on FECRT results. METHODS: Two commercial sheep farms were selected on the basis of having previously recorded FECR <95% after treatment with ivermectin (Farm 1) or albendazole (Farm 2). On each farm at least 250 lambs, managed as a single mob, were individually ear-tagged and sampled for FEC. The resulting counts were used, 3—4 days later, to sort the lambs into 24 groups of 10. First, the animals were split into three groups of 80, having high, medium or low FEC. Second, within each of these groups the 80 animals were further divided into four replicate mobs of 20 (each with the same mean count). Third, each of these replicates was further split into two groups of 10: those that would be drenched and those that would remain as untreated controls. All animals were again faecal-sampled and those in the drenched groups were dosed, using a syringe, to their individual liveweight, with ivermectin (Farm 1) or albendazole (Farm 2). Ten days after treatment all animals were individually faecal- sampled again. FEC and larval cultures were undertaken for all 24 groups from both pre- and post-treatment samples. Ef- ficacy (FECR) of the undifferentiated FECRT was calculated using three different equations, and efficacy by genus was also calculated. RESULTS: Calculated efficacies differed between equations, and the equation which did not utilise an untreated control yielded significantly lower efficacy estimates on both farms. Faecal cultures varied considerably in the proportions of parasite genera recovered. In general, this did not differ between FEC groups, except on Farm 1 where Haemonchus spp were more common and Cooperia spp less common in high-FEC samples. Estimated efficacies against individual genera varied considerably or very little, depending on the level of resistance. On both farms, differing proportions of tests against some genera passed or failed FECRTs based on a threshold pass mark of ≥95% FECR. CONCLUSION: There was considerable variability in the outcomes of FECRTs and in larval culture results. Caution is warranted in interpreting the results of FECRTs when efficacy values fall into the 90—95% range. Further, the possibility of a test returning a false-negative result is raised, indicating that even an efficacy estimated ≥95% may not guarantee the absence of resistant parasites. 相似文献
86.
87.
Reproductive Performance of Gilts with Similar Age but with Different Growth Rate at the Onset of Puberty Stimulation 总被引:1,自引:0,他引:1
R Kummer ML Bernardi AC Schenkel WS Amaral Filha I Wentz FP Bortolozzo 《Reproduction in domestic animals》2009,44(2):255-259
The aim of this study was to evaluate the reproductive performance of gilts that had a similar age but different weights at the onset of puberty stimulation by boar exposure at 144 days. Gilts were divided into two groups according to their lifetime growth rate from birth to approximately 144 days of age. Mean growth rates at this moment were 577 and 724 g/day for group 1 (G1; n = 58) and group 2 (G2; n = 58), respectively. After selection, gilts were weighed at approximately 155, 165 and 175 days of age, on the insemination day and at slaughter. Gilts were inseminated, on average, at 193 days of age and were slaughtered 32 days after insemination, when the number of corpora lutea and embryos were recorded. Higher growth rate gilts (G2) reached puberty earlier (155.3 vs 164.1 days; p < 0.01). More gilts of G2 group attained puberty by 190 days of age (p = 0.004) than G1 gilts (95%; 55/58 vs 76%; 44/58). The anoestrous rate, until 60 days after the onset of boar exposure was higher (p < 0.01) in G1 (19.0%; 11/58) than in G2 (3.4%; 2/58) group. However, there were no differences in the pregnancy rate (90.7 vs 94.5), ovulation rate (15.9 vs 16.5), total embryos (12.9 vs 11.7), viable embryos (12.0 vs 11.1) and embryo survival (73.7% vs 68.5%), between G1 gilts and G2 gilts, respectively (p > 0.05). High growth rate gilts attain puberty earlier and have a lower anoestrous rate than low growth rate gilts. 相似文献
88.
A parathyroid hormone-related protein implicated in malignant hypercalcemia: cloning and expression 总被引:57,自引:0,他引:57
L J Suva G A Winslow R E Wettenhall R G Hammonds J M Moseley H Diefenbach-Jagger C P Rodda B E Kemp H Rodriguez E Y Chen 《Science (New York, N.Y.)》1987,237(4817):893-896
Humoral hypercalcemia of malignancy is a common complication of lung and certain other cancers. The hypercalcemia results from the actions of tumor factors on bone and kidney. We report here the isolation of full-length complementary DNA clones of a putative hypercalcemia factor, and the expression from the cloned DNA of the active protein in mammalian cells. The clones encode a prepro peptide of 36 amino acids and a mature protein of 141 amino acids that has significant homology with parathyroid hormone in the amino-terminal region. This previously unrecognized hormone may be important in normal as well as abnormal calcium metabolism. 相似文献
89.
90.
Moseley ME 《Science (New York, N.Y.)》1975,187(4173):219-225
I have discussed Chan Chan in terms of its political and economic characteristics because state organization had a pervasive impact on the growth and structure of the settlement. In this sense the capital of Chimor resembles Cuzco the Inca capital (1). Both metropolitan centers served as seats of Andean empires governed by noble classes headed by members of royal dynasties. Each state relied on a system of labor taxation and controlled the production, collection, and redistribution of goods. These political and economic institutions gave the sites distinctive but parallel forms. First, the settlements were large, containing a great deal of monumental architecture, but size and construction do not reflect substantial populations because building was done by nonresident work forces. Second, the urban proletariat were relatively few in numbers and composed of retainers or service personnel at Cuzco, as well as craftsmen and artisans at Chan Chan. Third, civic facilities were intended to serve the aristocracy and the state, not the common citizenry because these were governmental, not folk or popular, centers. And, fourth, palaces tied up a great amount of urban space because each monarch built his own seat of government during life and this became a monument to his name after death. In conclusion, I cannot say Chan Chan and Cuzco are necessarily typical of other prehistoric population centers in the region because these centers are little studied. I can, however, say Chan Chan was distinct from the preindustrial cities of Europe and Mesopotamia, but this is not surprising because the capital of Chimor was the product of distinctly Andean cultural institutions. 相似文献