全文获取类型
收费全文 | 64篇 |
免费 | 13篇 |
专业分类
7篇 | |
综合类 | 18篇 |
畜牧兽医 | 52篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 3篇 |
2013年 | 7篇 |
2011年 | 1篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2008年 | 1篇 |
2007年 | 2篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2003年 | 3篇 |
2002年 | 1篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1984年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有77条查询结果,搜索用时 15 毫秒
1.
SUMMARY Mean concentration of cadmium (Cd) in kidneys of hogget sheep from 67 flocks grazing in the Agricultural Region of Western Australia was tested for association with soil, pastoral, climatic and nutritional factors. Hoggets grazing pastures on acidic soils and soils with a sandy-textured surface had higher Cd concentrations in kidneys than hoggets grazing pastures on more alkaline soils or soils with a clay-textured surface. Application of more than 100 kg of phosphatic fertiliser during the past 3 years to loamy soils was also associated with greater Cd concentration in kidneys of the grazing animals. 相似文献
2.
DM Leathwick TS Waghorn CM Miller DS Atkinson NA Haack A-M Oliver 《New Zealand veterinary journal》2013,61(6):305-312
AIM: To determine whether drenching regimes for lambs by which a proportion (10%) of the heaviest animals was selectively left untreated, or animals are only drenched ‘on demand’ when faecal nematode egg counts (FEC) exceeded a threshold level, would result in measurable increases in parasite larval challenge in the autumn and/or decreases in the performance of lambs. METHODS: A replicated study compared three drenching strategies in which mobs of lambs (n=360 in total) received either: a five-drench preventive programme, administered to all animals (Treatment 1); a five-drench preventive programme, but the 10% heaviest animals left untreated each time (Treatment 2); or drench treatments administered only when FEC exceeded 500 eggs per gram of faeces (epg) (Treatment 3). After the five-drench programme, animals in Treatments 1 and 2 were treated according to FEC as for Treatment 3. A triple-combination drench containing ivermectin, oxfendazole and levamisole, administered orally, was used for all treatments. There were nine farmlets, allowing three replicates of each treatment, in a completely randomised design. Parasite infestations on pasture were measured in autumn by pasture plucks, and worm burdens were monitored in tracer lambs, while the performance of lambs was assessed by liveweight gains, fleece weights, and body condition and dag scores. RESULTS: Increased numbers of Haemonchus contortus and Trichostrongylus colubriformis larvae on pasture were found in the autumn on farmlets treating selectively or on-demand (Treatments 2 and 3). No differences were detected in other parasite species. Mean liveweight gains did not differ between treatments but some differences were detected between drenched and undrenched lambs in Treatment 2. Mean body condition and mean dag scores of lambs in Treatment 3 tended to be lower and higher, respectively, than those of lambs in Treatment 1; Treatment 2 was generally intermediate. CONCLUSIONS: Drenching strategies for lambs designed to slow the development of anthelmintic resistance, by increasing the pool of susceptible worms available to dilute resistant survivors after treatment, resulted in increased numbers of H. contortus and T. colubriformis but not other species of parasite on pasture. The increased parasite challenge to lambs in the autumn was associated with small production losses, which may be acceptable to farmers wishing to implement such strategies. It is clear that further work is required on the interaction between management practices and the population dynamics of parasites, especially with regard to creating pools of susceptible genotypes to slow the development of drench resistance. 相似文献
3.
W Zhou JM Thomas DS Shephard BFG Johnson D Ozkaya T Maschmeyer RG Bell Q Ge 《Science (New York, N.Y.)》1998,280(5364):705-708
The anionic ruthenium cluster carbonylates [Ru6C(CO)16]2- or [H2Ru10(CO)25]2- interspersed with bis(triphenylphosphino)iminium counterions (PPN+) are incorporated from solution into the pores of MCM-41 mesoporous silica (3 nanometers in diameter), where they form tightly packed arrays. These arrays were shown by high-resolution transmission electron microscopy, Fourier transform optical diffraction, and computer simulations to be well ordered both along and perpendicular to the axis of the cylindrical pores. In their denuded state produced by gentle thermolysis, the cluster carbonylates yield nanoparticles of ruthenium that are less well ordered than their assimilated precursors but show good activity as hydrogenation catalysts for hexene and cyclooctene. In both their as-prepared and denuded states, these encapsulated clusters are likely to exhibit interesting electronic and other properties. 相似文献
4.
A detailed discussion of the quantitative nature of 13C CPMAS NMR spectra as applied to solid samples, such as soil, is given. In particular, the influence of the cross-polarization (CP) time constant (TCH), the relaxation time constant of protons in the rotating frame (T1pH) and the contact time (tc) in the CPMAS experiment are considered. Three distinct quantitation regimes are numerically identified according to sample parameters tCH and T1PH > and the experimental choice of tc: (i) quantitation obtainable from a single CPMAS spectrum; (ii) quantitation obtainable from a series of CPMAS spectra; and (iii) quantitation not possible using CPMAS. Strategies for the measurement of sample parameters TCH and TipH are reviewed. When quantitation is not possible using CPMAS it is necessary to regress to the direct polarization (DP) of 13C nuclei. The sensitivity problems of DPMAS are discussed, as too are general factors that affect the quantitation of 13C data such as spinning sidebands. More specifically in relation to soil samples, the effects on quantitation arising from the presence of paramagnetics and the actual methods for the measurement of signal intensities are covered. 相似文献
5.
AG Loeser Z Shen DS Dessau DS Marshall CH Park P Fournier A Kapitulnik 《Science (New York, N.Y.)》1996,273(5273):325-329
Angle-resolved photoemission experiments reveal evidence of an energy gap in the normal state excitation spectrum of the cuprate superconductor Bi2Sr2CaCu2O8+delta. This gap exists only in underdoped samples and closes around the doping level at which the superconducting transition temperature Tc is a maximum. The momentum dependence and magnitude of the gap closely resemble those of the dx2-y2 gap observed in the superconducting state. This observation is consistent with results from several other experimental techniques, which also indicate the presence of a gap in the normal state. Some possible theoretical explanations for this effect are reviewed. 相似文献
6.
F Ronning C Kim DL Feng DS Marshall AG Loeser LL Miller JN Eckstein I Bozovic Z Shen 《Science (New York, N.Y.)》1998,282(5396):2067-2072
An angle-resolved photoemission study is reported on Ca2CuO2Cl2, a parent compound of high-Tc superconductors. Analysis of the electron occupation probability, n(k), from the spectra shows a steep drop in spectral intensity across a contour that is close to the Fermi surface predicted by the band calculation. This analysis reveals a Fermi surface remnant, even though Ca2CuO2Cl2 is a Mott insulator. The lowest energy peak exhibits a dispersion with approximately the &cjs3539;coskxa - coskya&cjs3539; form along this remnant Fermi surface. Together with the data from Dy-doped Bi2Sr2CaCu2O8+delta, these results suggest that this d-wave-like dispersion of the insulator is the underlying reason for the pseudo gap in the underdoped regime. 相似文献
7.
Suberoylanilide hydroxamic acid,a novel histone deacetylase inhibitor,improves the development and acetylation level of miniature porcine handmade cloning embryos 下载免费PDF全文
Histone deacetylase inhibitors (HDACis) can change the histone acetylation and significantly enhance the developmental competence of the pre‐implantation SCNT embryo. To select a proper histone deacetylase inhibitor to improve the success rate and potentially developmental ability of handmade cloning (HMC) embryos of miniature porcine, we compared the effect of two histone deacetylase inhibitors (SAHA vs. VPA) on HMC embryo development, their histone acetylation level and the expression level of relevant genes. The blastocyst rate and number of blastocyst cells of HMC embryos treated with SAHA (SAHA‐HMC) or VPA (VPA‐HMC) were significantly higher than those of control (Control‐HMC), respectively, but there were no significant difference between SAHA‐HMC and VPA‐HMC groups. In addition, the acetylation level (AcH4K8) of Control‐HMC and VPA‐HMC embryos at the blastocyst stage, respectively, was significantly lower than that of in vitro fertilized (IVF) and SAHA‐HMC embryos. However, the acetylation H4K8 of the blastocysts had no significant difference between SAHA‐HMC and the IVF groups. The SAHA‐HMC blastocysts indicated comparative expression levels of Oct4 and HDAC1 (histone deacetyltransferase gene) with those of IVF blastocysts. In contrast, the expression levels of Oct4 were lower and those of HDAC1 were higher in the VPA‐HMC and Control‐HMC blastocysts, respectively, compared to those of the IVF blastocysts. Our results demonstrated that the HMC embryos treated by SAHA could promote the pre‐implantation development and increase the levels of histone H4K8 acetylation and the expression of the OCT4 gene, yet decrease the expression of the HDAC1 gene to the comparable level of the IVF embryos. Our results proved that SAHA may be a better histone deacetylase inhibitor for porcine HMC compared to VPA, and furthermore, it may indicate that SAHA can effectively correct the abnormal histone acetylation during the HMC embryo development and subsequently improve the full‐term developmental potential of the HMC embryos after embryo transplantation. 相似文献
8.
Tom MISSELBROOK Zhaohai BAI Zejiang CAI Weidong CAO Alison CARSWELL Nicholas COWAN Zhenling CUI David CHADWICK Bridget EMMETT Keith GOULDING Rui JIANG Davey JONES Xiaotang JU Hongbin LIU Yuelai LU Lin MA David POWLSON Robert M. REES Ute SKIBA Pete SMITH Roger SYLVESTER-BRADLEY John WILLIAMS Lianhai WU Minggang XU Wen XU Fusuo ZHANG Junling ZHANG Jianbin ZHOU Xuejun LIU 《农业科学与工程前沿(英文版)》2022,9(3):475
9.
10.
D. S. POWLSON 《European Journal of Soil Science》1980,31(1):77-85
Grinding more than doubled the respiration rate of two silt loam soils, one arable and one grassland. The increases were smaller when the grinding treatment was given to portions of soils that had previously been fumigated with CHCI3and incubated, a treatment that greatly decreased microbial biomass. The results indicate that the flush of decomposition caused by grinding was in part derived from killed organisms and in part from enhanced decomposition of non-biomass sections of the soil organic matter. Grinding killed about a quarter of the biomass in both soils. Carbon from killed organisms accounted for a quarter of the extra CO2–C evolved after grinding in the arable soil and almost half in the grassland soil. The extra non-biomass organic matter decomposing after grinding amounted to about 0.5% of the soil organic carbon in both soils. This non-biomass material rendered decomposable by grinding had a higher C/N ratio than the organic matter decomposing in unground soil. 相似文献