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排序方式: 共有133条查询结果,搜索用时 31 毫秒
81.
Naja Steen Andersen Gert Poulsen Bente Anni Andersen Lars Pødenphant Kiær Tina D’Hertefeldt Mike J. Wilkinson Rikke Bagger Jørgensen 《Genetic Resources and Crop Evolution》2009,56(2):189-200
When planning optimal conservation strategies for wild and cultivated types of a plant species, a number of influencing biological
and environmental factors should be considered from the outset. In the present study Brassica rapa was used to illustrate this: to develop Scandinavian conservation strategies for wild and cultivated B. rapa, DNA-marker analysis was performed on 15 cultivated and 17 wild accessions of B. rapa plus 8 accessions of the cross compatible B. napus. The B. rapa cultivars were bred in Sweden and Finland in 1944–1997 and the wild B. rapa material was collected from Denmark, Sweden and United Kingdom. The B. napus accessions were bred within the last 20 years in the Scandinavian countries. Results were based on scoring of 131 polymorphic
ISSR markers in the total plant material. A Bayesian Markov chain Monte Carlo (MCMC) approach implemented in NewHybrids demonstrated
a clear distinction of B. rapa and B. napus individuals except for three individuals that seemed to be backcrosses. The backcrossed hybrids descended from two Swedish
populations, one wild and one escaped. The overall pattern of genetic variation and structure in B. rapa showed that cultivated and wild B. rapa accessions formed two almost separated clusters. Geographical origin and breeding history of cultivars were reflected in
these genetic relationships. In addition, wild populations from Denmark and Sweden seemed to be closely related, except for
a Swedish population, which seemingly was an escaped cultivar. The study point to that many processes, e.g. spontaneous introgression,
naturalisation, breeding and agricultural practise affected the genetic structure of wild and cultivated B. rapa populations. 相似文献
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84.
Aper J Mechant E Rubin B Heyerick A Callebaut G Mangelinckx S Deforce D De Kimpe N Bulcke R Reheul D 《Pest management science》2012,68(2):209-216
BACKGROUND: In recent years, common lambsquarters (Chenopodium album L.) populations from sugar beet fields in different European countries have responded as resistant to the as‐triazinone metamitron. The populations have been found to have the same D1 point mutation as known for atrazine‐resistant biotypes (Ser264 to Gly). However, pot experiments revealed that metamitron resistance is not as clear‐cut as observed with triazine resistance in the past. The objectives of this study were to clarify the absorption, translocation and metabolic fate of metamitron in C. album. RESULTS: Root absorption and foliar absorption experiments showed minor differences in absorption, translocation and metabolism of metamitron between the susceptible and resistant C. album populations. A rapid metabolism in the C. album populations was observed when metamitron was absorbed by the roots. The primary products of metamitron metabolism were identified as deamino‐metamitron and metamitron‐N‐glucoside. PABA, known to inhibit the deamination of metribuzin, did not alter the metabolism of metamitron, and nor did the cytochrome P450 inhibitor PBO. However, inhibition of metamitron metabolism in the presence of the cytochrome P450 inhibitor ABT was demonstrated. CONCLUSION: Metamitron metabolism in C. album may act as a basic tolerance mechanism, which can be important in circumstances favouring this degradation pathway. Copyright © 2011 Society of Chemical Industry 相似文献
85.
Massive phytoplankton blooms under Arctic sea ice 总被引:3,自引:0,他引:3
Arrigo KR Perovich DK Pickart RS Brown ZW van Dijken GL Lowry KE Mills MM Palmer MA Balch WM Bahr F Bates NR Benitez-Nelson C Bowler B Brownlee E Ehn JK Frey KE Garley R Laney SR Lubelczyk L Mathis J Matsuoka A Mitchell BG Moore GW Ortega-Retuerta E Pal S Polashenski CM Reynolds RA Schieber B Sosik HM Stephens M Swift JH 《Science (New York, N.Y.)》2012,336(6087):1408
Phytoplankton blooms over Arctic Ocean continental shelves are thought to be restricted to waters free of sea ice. Here, we document a massive phytoplankton bloom beneath fully consolidated pack ice far from the ice edge in the Chukchi Sea, where light transmission has increased in recent decades because of thinning ice cover and proliferation of melt ponds. The bloom was characterized by high diatom biomass and rates of growth and primary production. Evidence suggests that under-ice phytoplankton blooms may be more widespread over nutrient-rich Arctic continental shelves and that satellite-based estimates of annual primary production in these waters may be underestimated by up to 10-fold. 相似文献
86.
Klocke NW Snyder PW Widmer WR Zhong W McCabe GP Breur GJ 《American journal of veterinary research》2005,66(3):493-499
OBJECTIVE: To test the hypotheses that the densities of macrophages in the synovial membranes and capsules of stifle joints in dogs with ruptured cranial cruciate ligaments are greater than those of normal joints and that those densities in affected joints are positively correlated with the chronicity and severity of the disease. ANIMALS: 17 dogs with naturally occurring rupture of the cranial cruciate ligament and 5 healthy control dogs. PROCEDURE: All dogs underwent orthopedic and radiographic evaluations. In affected dogs, duration of clinical signs was used as an indicator of disease chronicity and the severity of osteoarthritis in the stifle joint was determined radiographically. Joint capsule specimens were evaluated histologically; macrophages, interleukin-6, and tumor necrosis factor-alpha were identified by use of immunocytochemical techniques. RESULTS: Compared with unaffected joints, macrophage density was increased in all affected joints. Duration of disease was significantly associated with radiographic severity of osteoarthritis and synovial macrophage density. Synovial macrophage density was significantly associated with severity of osteoarthritis and with the presence of interleukin-6 and tumor necrosis factor-a. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that synovial macrophages may be involved in the development of pathologic changes (including osteophyte formation) in the stifle joints of dogs with osteoarthritis secondary to rupture of the cranial cruciate ligament. Determination of the importance of synovial macrophages in the development of changes in osteoarthritic joints may result in new treatment strategies that involve elimination of the deleterious effects of those cells. 相似文献
87.
A large-scale epidemiological study was conducted to determine breeds at risk for 12 developmental orthopedic diseases (DODs). Developmental orthopedic diseases investigated included canine hip dysplasia (CHD); craniomandibular osteopathy (CMO); fragmented coronoid process; hypertrophic osteodystrophy; Legg-Calvé-Perthes disease; osteochondrosis of the medial humeral condyle, caudal humeral head, femoral condyles, and talar trochlear ridges; panosteitis; patella luxation; and ununited anconeal process. Dogs that were diagnosed with any one of the diseases of interest at any of 10 veterinary teaching hospitals participating in the Veterinary Medical Database from 1986 to 1995 were included as cases. Odds ratios and corresponding 95% confidence intervals were calculated to determine risk. Frequency of diagnosis during the 10-year period ranged from 35 cases (CMO) to 10,637 cases (CHD). The number of breeds at increased risk for a disease ranged from one (CMO) to 35 (CHD). Breed susceptibility for a DOD may suggest a genetic component in the disease etiology. The results of this study serve to increase veterinarians' awareness of breeds susceptible to DODs and may facilitate the control of such diseases by identifying breeds that might benefit from breeding programs or environmental intervention such as dietary modification. 相似文献
88.
ABSTRACT Specific resistances to isolates of the ascomycete fungus Mycosphaerella graminicola, which causes Septoria tritici blotch of wheat, have been detected in many cultivars. Cvs. Flame and Hereward, which have specific resistance to the isolate IPO323, were crossed with the susceptible cv. Longbow. The results of tests on F1 and F2 progeny indicated that a single semidominant gene controls resistance to IPO323 in each of the resistant cultivars. This was confirmed in F3 families of Flame x Longbow, which were either homozygous resistant, homozygous susceptible, or segregating in tests with IPO323 but were uniformly susceptible to another isolate, IPO94269. None of 100 F2 progeny of Flame x Hereward were susceptible to IPO323, indicating that the resistance genes in these two cultivars are the same, closely linked, or allelic. The resistance gene in cv. Flame was mapped to the short arm of chromosome 3A using microsatellite markers and was named Stb6. Fifty-nine progeny of a cross between IPO323 and IPO94269 were used in complementary genetic analysis of the pathogen to test a gene-for-gene relationship between Stb6 and the avirulence gene in IPO323. Avirulence to cvs. Flame, Hereward, Shafir, Bezostaya 1, and Vivant and the breeding line NSL92-5719 cosegregated, and the ratio of virulent to avirulent was close to 1:1, suggesting that these wheat lines may all recognize the same avirulence gene and may all have Stb6. Together, these data provide the first demonstration that isolate-specific resistance of wheat to Septoria tritici blotch follows a gene-for-gene relationship. 相似文献
89.
Toxicity measurements were made with three closely-related Bollworm species, Heliothis virescens F., Helicoverpa zea (Boddie), and Helicoverpa armigera (Huebner) using insecticides of 3 different chemical classes. Tests were carried out by a leaf-dip method using neonate larval stages, a topical application test on 3rd larvae, and a topical test with imagines. H. armigera populations from Ivory Coast, Turkey, Thailand, and India were obtained and investigated. H. virescens originated from the USA and Colombia, and H. zea from Guatemala and Nicaragua. Resistance was expressed in all species, the sensitive reference strains having similar LC50s in tests with monocrotophos, profenofos, thiodicarb, and methomyl. Since resistance appeared not to be a quality related to species but rather a feature common to all of the samples investigated, its origin must be connected with the type of cotton culture and the selection pressure they were subjected to in their respective agro-ecosystem. Resistance was highest for monocrotophos and cypermethrin in Central American countries, differences in the treatment regime being reflected by the resistance levels attained. In all stages tested, resistance was sufficiently well expressed to make a monitoring system based on neonate larvae, the 3rd larval stage, or imagines of the species possible. The final decision as to which should be used for a general, comparative monitoring system, therefore, should be governed by the technical parameters of the testing process. 相似文献
90.
Alexander Peringer Kiowa A. Schulze Ileana Stupariu Mihai-Sorin Stupariu Gert Rosenthal Alexandre Buttler François Gillet 《Landscape Ecology》2016,31(4):913-927