全文获取类型
收费全文 | 181篇 |
免费 | 8篇 |
专业分类
林业 | 7篇 |
农学 | 1篇 |
16篇 | |
综合类 | 53篇 |
农作物 | 2篇 |
水产渔业 | 2篇 |
畜牧兽医 | 96篇 |
植物保护 | 12篇 |
出版年
2020年 | 2篇 |
2018年 | 2篇 |
2016年 | 5篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 17篇 |
2012年 | 3篇 |
2011年 | 10篇 |
2010年 | 5篇 |
2007年 | 6篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 1篇 |
1972年 | 9篇 |
1971年 | 3篇 |
1970年 | 5篇 |
1969年 | 4篇 |
1968年 | 2篇 |
1967年 | 4篇 |
1966年 | 4篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1963年 | 2篇 |
1962年 | 1篇 |
1940年 | 1篇 |
1903年 | 1篇 |
1899年 | 2篇 |
1897年 | 2篇 |
排序方式: 共有189条查询结果,搜索用时 31 毫秒
1.
2.
Thirty of 200 ewes died or were euthanatized during a 21-day period following a 1-day accidental exposure to natural gas condensate, a complex mixture of hydrocarbons obtained during collection of natural gas from wells. Despite access to potable well water, the poisoned ewes willingly consumed toxic doses of condensate that contaminated surface water. Eight animals died without premonitory signs; the remainder became ill over the course of a few days to 3 weeks. The principal cause of mortality was aspiration pneumonia, but myocardial degeneration and necrosis, renal tubular damage, gastritis, enteritis, and meningeal edema and hyperemia were also observed. Gas chromatographic analysis identified chemical traces of the hydrocarbons in the tissues, and "fingerprinting," the process of matching chromatographic tracings, provided forensic proof of the contamination source. Atomic absorption spectroscopy and cholinesterase analyses were performed to eliminate the possibility of toxicosis by heavy metal contaminants or other constituents. This appears to be the first reported incidence of natural gas condensate toxicity involving sheep or other ruminants. Although the available literature presents a suggestive pattern of clinical signs and pathologic lesions of petroleum product poisoning, diagnostic investigations should employ detailed analytic examination because each source of petroleum hydrocarbons contains unique sets of components that may produce different toxic effects. 相似文献
3.
4.
To determine the potential of sexual reproduction among host-adapted populations of Phytophthora infestans sensu lato in Ecuador, 13 A1 isolates belonging to clonal lineages US-1, EC-1 and EC-3, and 11 A2 isolates belonging to the clonal lineage EC-2, were paired on agar plates to induce crossing. In the first experiment, six A1 isolates (three US-1, two EC-1 and one EC-3) were each crossed with three A2 isolates (total = 18 crosses). Matings involving isolates of the EC-1 lineage produced more oospores of healthy appearance than did matings with isolates of US-1 or EC-3. In the second experiment, the oospores of 35 crosses (21 EC-1 × EC-2; 10 US-1 × EC-2; four EC-3 × EC-2) were dispersed on water agar to assess oospore germination. Overall, germination percentages were low. Only one cross produced enough progeny for evaluation. Twenty-three single-oospore offspring were isolated and evaluated for mating type; electrophoretic patterns of glucose-6-phosphate isomerase ( Gpi ) and peptidase ( Pep ) alloenzyme loci; mitochondrial DNA haplotype; and genomic DNA fingerprint. Multilocus genotype data indicated that all 23 isolates resulted from meiotic recombination. Four progeny with homothallic phenotype appeared to be unstable heterokaryons. Markers at several loci segregated according to simple Mendelian expectations for a diploid organism, but the ratios of three RFLP loci and the Pep locus were not consistent with Mendelian expectations. All progeny were nonpathogenic on hosts of the parental genotypes. Reduced mating success and reduced pathogenic fitness of progeny appear to be postmating mechanisms of reproductive isolation in populations of P. infestans sensu lato in Ecuador. 相似文献
5.
Tatiana C. Weisbrod Ramiro Isaza Carolyn Cray Laurie Adler Nicole I. Stacy 《The Veterinary quarterly》2021,41(1):30
Unique features of elephant hematology are known challenges in analytical methodology like two types of monocytes typical for members of the Order Afrotheria and platelet counts of the comparatively small elephant platelet. To investigate WBC differential and platelet data generated by an impedance-based hematology analyzer without availability of validated species-specific software for recognition of elephant WBCs and platelets, compared to manual blood film review. Blood samples preserved in ethylenediaminetetraacetic acid (EDTA) of 50 elephants (n = 35 Elephas maximus and n = 15 Loxodonta africana) were used. A Mann-Whitney test for independent samples was used to compare parameters between methods and agreement was tested using Bland-Altman bias plots. All hematological variables, including absolute numbers of heterophils, lymphocytes, monocytes, eosinophils, basophils, and platelets, were significantly different (p < 0.0001) between both methods of analysis, and there was no agreement using Bland-Altman bias plots. Manual review consistently produced higher heterophil and monocyte counts as well as platelet estimates, while the automated analyzer produced higher lymphocyte, eosinophil, and basophil counts. The hematology analyzer did not properly differentiate elephant lymphocytes and monocytes, and did not accurately count elephant platelets. These findings emphasize the importance of manual blood film review as part of elephant complete blood counts in both clinical and research settings and as a basis for the development of hematological reference intervals. 相似文献
6.
Flowing solution culture enables the researcher to study effects of root environment variables independently. This flowing solution culture system utilizes air pressure and syphoning or a peristaltic pump to circulate the nutrient solution. Because this system is inexpensive, simple in design, and compact, several factors can be studied concurrently, treatments can be replicated to test for system effects, nutrient deviations, and block for growth effects due to environment. These systems have been used successfully with experiments in N form, plant growth regulators, salt stress, and mechanical stress. Non‐destructive measurements of root growth and nutrient uptake are possible. 相似文献
7.
Klaus Adler 《Genetic Resources and Crop Evolution》1967,15(1):151-160
Zusammenfassung Es wird eine Meßanordnung zur amperometrischen Registrierung der relativen Nettosauerstoffaustauschrate mittels einer membrangeschützten Platinelektrode beschrieben, die besonders für die Verwendung kleiner Versuchsobjekte (einzelliger Algen und isolierter Chloroplasten) geeignet ist. Die hohe Empfindlichkeit ermöglicht die Analyse von Sauer-stoffaustauschraten unter Verwendung monochromatischen Lichtes relativ hoher spektraler Reinheit. Die gute Stabilität des Elektrodenpotentials läßt eine große Verstärkung des Meßwertes und eine direkte Registrierung des Anstiegs der relativen Sauerstoffaustauschrate zu.
Summary An amperometric device is described for the registration of relative oxygen exchange rates of small particles such as algae or isolated chloroplasts. The high sensitivity of the electrode according to the Clark-type make possible the application of monochromatic light with small half band wides for examination of photosynthetic reactions. The employed Ag/AgO-reference electrode has a very stable potential and allows a high amplification necessary for direct registration of the oxygen exchange rate derivatives. Some examples are given for registrated exchange rates.
¶rt;- ¶rt;, . , , , . . . .相似文献
8.
The migration test on circulating bovine leukocytes and its possible application in the diagnosis of Johne's disease 总被引:3,自引:0,他引:3
The leukocyte migration test for in vitro studies of delayed type hypersensitivity has recently been reviewed (Søborg & Ben-dixen 1967; Bendixen & Søborg 1969). Søborg & Bendixen applied the test to circulating leukocytes in man and thereby widely increased the potentialities of this test. They obtained high leukocyte yields with only moderate erythrocyte admixture by harvesting the supernatant plasma after sedimentation of the erythrocytes for 60 min. at 37°C in the normal gravitational field (1 × g)- Their procedure was unsuitable for the present investigation because bovine erythrocytes sediment so slowly. Sedimentation after clumping at the interphase of aqueous solutions of polymers, dextran and methylcellulose, in combination with metrizoic acid (Böyum 1968) was tried without success because the vast majority of the leukocytes sedimented together with the erythrocytes. Separation of leukocytes from erythrocytes could not be achieved by differential centrifugation. 相似文献
9.
Canine visceral leishmaniasis (VL), caused by Leishmania infantum (Leishmania chagasi in the New World), is a zoonotic, endemic disease in Western Europe and Latin America. The potential spreading to new regions was suggested by the appearance of canine VL among foxhounds in the US. Although the sand fly vectors in the major foci of transmission have been described, no information exists on other sand flies that could propagate the infection outside endemic areas. We evaluated the capacity of Lutzomyia shannoni (Dyar) and Lutomyia youngi (Feliciangeli & Murillo), which are widely distributed in the New World, to acquire L chagasi (Cunha and Chagas) infections. A high proportion of L youngi were infected after feeding on an oligosymptomatic dog (51 per cent) or a polysymptomatic individual (95 per cent), but the intensity of infection was low (< 200 promastigotes/fly). L shannoni became infected only by feeding on the polysymptomatic dog, and the infection rate was lower (9 per cent) than in Lutzomyia longipalpis (36 per cent), and Lutzomyia evansi (Nunez-Tovar) (Lutz and Neiva) (38 per cent), but the intensity of infection (200 to > 500 promastigotes/fly) was comparable (L longipalpis) or higher (L evansi) than in the New World vectors. It is hypothesised that the presence of infected dogs in areas where L shannoni or L youngi occur could initiate new endemic cycles of VL in both South and North America. 相似文献
10.
R J Chappel B Adler S A Ballard S Faine R T Jones B D Millar J A Swainger 《Veterinary microbiology》1985,10(3):279-286
An enzymatic radioimmunoassay (ERIA) has been developed for detecting Leptospira interrogans serovar pomona in porcine urine. Four grower pigs were experimentally infected with serovar pomona. A total of 39 urine samples was collected, and ERIA was compared with dark ground microscopy (DGM) and culture for demonstrating leptospiruria. Of 20 samples positive by at least one technique, leptospires were detected by ERIA in 14, by culture in 16 and by DGM in 13. ERIA, unlike the other 2 methods, was suitable for use with urine which had been stored frozen for several months. 相似文献