全文获取类型
收费全文 | 79篇 |
免费 | 3篇 |
专业分类
林业 | 1篇 |
农学 | 1篇 |
10篇 | |
综合类 | 20篇 |
农作物 | 1篇 |
畜牧兽医 | 48篇 |
植物保护 | 1篇 |
出版年
2021年 | 1篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2013年 | 3篇 |
2012年 | 1篇 |
2011年 | 2篇 |
2010年 | 1篇 |
2009年 | 5篇 |
2008年 | 2篇 |
2007年 | 1篇 |
2006年 | 6篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 5篇 |
2002年 | 7篇 |
2001年 | 1篇 |
1999年 | 1篇 |
1998年 | 7篇 |
1996年 | 6篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1983年 | 1篇 |
1978年 | 3篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有82条查询结果,搜索用时 0 毫秒
61.
62.
When Aspergillus niger or a Penicillium sp. were grown in potato dextrose broth supplemented with chlorsulfuron, the herbicide concentration decreased by 97–99% within 78–96 h and the pH of the medium fell from 7.2 to between 2.4 and 3.1. If, during growth, the pH was maintained at or near neutrality, no decrease in herbicide concentration occurred. When sterile medium containing the herbicide was titrated with acid to mimic acid formation during fungal growth, the herbicide concentration again declined. Precipitation was not responsible for the observed decrease. The data indicate that, in laboratory media, these fungi do not directly metabolise the herbicide as previously thought. Chlorsulfuron degradation in perfused soil cores was not enhanced by inoculation with A. niger. Our results show that A. niger and a Penicillium sp. do not degrade chlorsulfuron. 相似文献
63.
JB MOLLOY PM BOWLES DP KNOWLES TF McELWAIN RE BOCK TG KINGSTON GW BLIGHT RJ DALGLIESH 《Australian veterinary journal》1999,77(4):245-249
OBJECTIVE: To compare a recently developed recombinant MSP-5 competitive inhibition ELISA with a card agglutination test for detection of antibodies to Anaplasma marginale and Anaplasma centrale in Australian cattle. MATERIALS AND METHODS: The ELISA was compared with the card agglutination test using 208 sera from cattle in Anaplasma-free herds, 86 sera from cattle experimentally infected with A marginale or A centrale and 757 sera from cattle in areas endemic for A marginale. RESULTS: The specificity of the ELISA, based on testing 208 sera from cattle in Anaplasma-free areas, was 99.5%, and the sensitivities for detection of antibodies to A marginale and A centrale in sera from the experimentally infected cattle were 98.0% and 100%, respectively. For the same sets of sera, the specificity of the card agglutination test was 98.6% and the sensitivities for detection of antibodies to A marginale and A centrale were 98.0% and 100%, respectively. For the 757 sera collected from cattle in areas endemic for A marginale, the agreement between the ELISA and the card agglutination test depended on the positive threshold selected for the ELISA. The maximum achievable agreement was 91.5% (kappa = 0.73; 95% confidence interval 0.66, 0.79). CONCLUSION: We conclude that the competitive inhibition ELISA is a useful alternative to the card agglutination test for detection of A marginale or A centrale infection in cattle. The assay should be particularly useful for epidemiological applications such as prevalence studies and control programs. 相似文献
64.
LG Devito CB Fernandes IDP Blanco PM Tsuribe FC Landim‐Alvarenga 《Reproduction in domestic animals》2010,45(4):654-658
Intracytoplasmic sperm injection (ICSI) consists of the introduction, by micromanipulation, of a single sperm into the cytoplasm of a mature egg. This technique is particularly advantageous when only a few sperm are available for fertilization, representing an important tool in preserving genetic material, especially from poorly fertile males. The results from ICSI in cattle are very often unsatisfactory and difficult to reproduce. Thus, the goal of this study was to evaluate the effect of the use of a Piezo drill (PD) and oocyte activation with ionomycin + roscovitine (I + R) during ICSI in cattle oocytes. After in vitro maturation (24 h), cumulus complex oocytes were divided into four groups: G1 – the ICSI was performed without the use of a PD and the oocyte was activated with I + R; G2 – the ICSI was performed with the use of the PD and activation with I + R; G3 – the ICSI was performed with the use of the PD, but without activation and G4 – parthenogenetic control, treated with I + R, but without sperm injection. The presumptive zygotes were cultured for 7 days and evaluated on day 3 for cleavage rate and on day 7 for blastocyst formation. Embryo production by standard in vitro fertilization in the laboratory was 78% for cleavage (117/150) and 35% for blastocyst formation (41/150). The cleavage rates obtained in G1, G2 and G4 were similar (66.7%, 71.6% and 66.3%, respectively), demonstrating the beneficial effect of oocyte activation. However, in G3, despite the presence of the sperm and the electric stimulation of a PD, the cleavage rates were significantly lower (17.5%) compared with the groups that used chemical activation, even in the absence of sperm (G4). Despite the beneficial effects of activation, this stimulus alone, or in the absence of the PD, was not sufficient for adequate morulae formation (13.4%, 37.9%, 0.0% and 13.5% for G1, G2, G3 and G4, respectively). Only in G2, when the PD was used followed by artificial activation, blastocysts were obtained (14.7%). These results indicate that cattle oocytes must be activated after ICSI to produce viable embryos. 相似文献
65.
The clementine mission to the moon: scientific overview 总被引:4,自引:0,他引:4
Nozette S Rustan P Pleasance LP Kordas JF Lewis IT Park HS Priest RE Horan DM Regeon P Lichtenberg CL Shoemaker EM Eliason EM McEwen AS Robinson MS Spudis PD Acton CH Buratti BJ Duxbury TC Baker DN Jakosky BM Blamont JE Corson MP Resnick JH Rollins CJ Davies ME Lucey PG Malaret E Massie MA Pieters CM Reisse RA Simpson RA Smith DE Sorenson TC Breugge RW Zuber MT 《Science (New York, N.Y.)》1994,266(5192):1835-1839
In the course of 71 days in lunar orbit, from 19 February to 3 May 1994, the Clementine spacecraft acquired just under two million digital images of the moon at visible and infrared wavelengths. These data are enabling the global mapping of the rock types of the lunar crust and the first detailed investigation of the geology of the lunar polar regions and the lunar far side. In addition, laser-ranging measurements provided the first view of the global topographic figure of the moon. The topography of many ancient impact basins has been measured, and a global map of the thickness of the lunar crust has been derived from the topography and gravity. 相似文献
66.
A preliminary investigation comparing pre-operative morphine and buprenorphine for postoperative analgesia and sedation in cats 总被引:1,自引:1,他引:1
GW Stanway BVSC Cert VA PM Taylor MA Vet MB PhD DVA Dip ECVA & DC Brodbelt† MA Vet MB DVA Dip ECVA MRCVS 《Veterinary anaesthesia and analgesia》2002,29(1):29-35
Objective To compare the postoperative analgesic and sedative properties of buprenorphine and morphine in cats. Study Design Prospective, randomized, blinded study. Animals Thirty‐two domestic cats undergoing surgery. Methods Cats received pre‐anaesthetic medication with acepromazine (0.05 mg kg?1) given intramuscularly and were randomly allocated to group M and given morphine (0.1 mg kg?1) intramuscularly (IM) or to group B and given buprenorphine (0.01 mg kg?1) IM. Anaesthesia was induced with propofol and maintained with halothane in oxygen and nitrous oxide. Pain and sedation scores using visual analogue scales, and heart and respiratory rates, were measured immediately before, and 30, 60, 120, 180, 300 and 420 minutes after anaesthesia. Results Pain scores were significantly lower at 60, 120 and 180 minutes after anaesthesia in group B. Group B also had higher heart rates at 30 minutes. There were no other statistically significant differences between the groups. Clinical relevance Buprenorphine (0.01 mg kg?1) appeared to provide better postoperative analgesia than morphine (0.1 mg kg?1) and may also have a longer duration of action. 相似文献
67.
In the current survey, there was no clear evidence that GM (genetically modified) crops are higher yielding than those conventionally bred<fnoteref rid="fn1">1</fnoteref>. Furthermore, there were no trials to support valid comparisons of yield per se. This article investigates GM crop yields, introducing the importance of hybrid vigour and a non-stress environment for higher percentage heritability selection and therefore more productive conventional plant breeding and improved crops. GM technology and crops are compared with proven plant breeding methods, with respect to hybrid vigour and the economic viability of both systems. These proven methods of plant breeding are (1) traditional landrace cropping, (2) conventional Mendelian breeding and (3) Isolection Mendelian breeding, and are also considered historically. 相似文献
68.
Van R. Haden Jing Xiang Shaobing Peng Bas A. M. Bouman Romeo Visperas Quirine M. Ketterings Peter Hobbs John M. Duxbury 《植物养料与土壤学杂志》2011,174(2):292-300
Recent studies have documented adverse affects of urea on the establishment and growth of aerobic rice when applied at seeding. The following experiments were conducted to examine the relative importance of ammonia and nitrite (NO$ _2^- $ ) toxicities as mechanisms contributing to poor germination and early growth of aerobic rice. Soil was collected from an experiment in the Philippines where aerobic rice was grown continuously for 7 years. Subsamples of the soil were: (1) pretreated with sulfuric acid (0.5 M H2SO4 added at 75 mL kg–1), (2) oven‐heated at 120°C for 12 h, or (3) left untreated. In a greenhouse study N was applied to the untreated, acidified, and oven‐heated soils as either urea or ammonium sulfate (0.0 or 0.3 g N kg–1). Plant height, root length, total biomass, and number of seminal roots were evaluated after 10 d. Microdiffusion incubations were used to assess the effects of soil pretreatment, N source, and N rate (0, 0.5, 1.0, 1.5 g N kg–1) on ammonia (NH3) volatilization and germination. Nitrite incubations were conducted to establish a critical level for NO$ _2^- $ toxicity and measure the extractable NO$ _2^- $ and germination trends as affected by soil pretreatment, N source, and N rate. On untreated soil, urea reduced early growth and germination while ammonium sulfate caused no adverse effects. Progressively higher rates of urea increased NH3 volatilization and inhibited germination, while oven‐heating and acidification minimized the adverse effects. All treatment combinations (soil pretreatment, N source, N rate) had extractable NO$ _2^- $ levels below the critical level of 0.2 g N kg–1, suggesting that ammonia and not NO$ _2^- $ toxicity was the principal cause of inhibition. Since the risk of NH3 toxicity is highest just following urea hydrolysis, strategies to optimize the timing and placement of urea should be considered. 相似文献
69.
It may be desirable to minimize dinitrogen (N2) fixation in alfalfa (Medicago saliva L.) when a source of inorganic nitrogen (N), such as manure, is readily available. Our objectives were to determine the N2 fixation response of eight alfalfa germplasms to inorganic N and to characterize plant‐to‐plant variation for this trait. Seed was sown in vermiculite and irrigated with nutrient solution in growth chambers. Herbage was removed at 71 d and treatments of 1, 3, 5, or 10 mM N were applied as 15N‐depleted ammonium nitrate (NH4NO3). After 34 d of regrowth, herbage was removed and analyzed for dry mass, total N concentration, and N isotope ratio. Increased availability of inorganic N resulted in a linear increase in herbage weight, height, shoot number, and N concentration, and consistently decreased N2 fixation for all germplasms. Estimated N2 fixation was greater than zero at the highest rate of inorganic N, which we speculate was due, in part, to remobilized root and crown N, because nodules appeared to be nonfunctional. Across all treatments, N2 fixation correlated best with herbage N concentration, but there was no relationship between these variables within a given N treatment concentration. Significant variation in reliance on N2 fixation in the presence of inorganic N existed in all eight germplasms. 相似文献
70.
Predatory dinosaur remains from madagascar: implications for the cretaceous biogeography of gondwana 总被引:1,自引:0,他引:1
SD Sampson LM Witmer CA Forster DW Krause PM O'Connor P Dodson F Ravoavy 《Science (New York, N.Y.)》1998,280(5366):1048-1051
Recent discoveries of fossil vertebrates from the Late Cretaceous of Madagascar include several specimens of a large theropod dinosaur. One specimen includes a nearly complete and exquisitely preserved skull with thickened pneumatic nasals, a median frontal horn, and a dorsal projection on the parietals. The new materials are assigned to the enigmatic theropod group Abelisauridae on the basis of a number of unique features. Fossil remains attributable to abelisaurids are restricted to three Gondwanan landmasses: South America, Madagascar, and the Indian subcontinent. This distribution is consistent with a revised paleogeographic reconstruction that posits prolonged links between these landmasses (via Antarctica), perhaps until late in the Late Cretaceous. 相似文献