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991.
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C. Fortes Ferreira M. Gonzaga Pereira A. da Silva dos Santos R. Rodrigues R.E. Bressan-Smith A. PioViana R. Figueiredo Daher 《Euphytica》2003,134(1):43-46
Among the main causes of poor yield in common beans are fungal, viral and bacterial diseases. Common bacterial blight, caused
by Xanthomonas axonopodis pv. phaseoli (Xap), is one of the major bacterial diseases leading to significant losses in Brazil. Chemical control is ineffective, therefore,
the use of resistant varieties becomes an interesting alternative. The objective of the present work was to evaluate disease
resistance under natural infection of the pathogen in 109 recombinant inbred lines (F7) of P. vulgaris originated from the cross HAB-52 (susceptible — snapbean) × BAC-6 (resistant — common bean) in two different environments,
as well as to calculate genetic parameters to assist in the selection of promising materials to be used in the CBB resistance
breeding program. The data of the genetic parameters were
compared to those calculated for the F3 generation originated from the same cross. The heritability results for DI (disease index) and VI (variation index) in F3 were 26.85% and 0.26, respectively, whereas in F7 they were 91.77% and 1.36, respectively. These results demonstrate a potential to be explored for this advanced population,
that in the future, along with other pathogen variability studies and tests in other environments, may provide more information
regarding a more precise evaluation of promising genotypes to be used in common bean breeding programs aiming to obtain CBB
resistant varieties.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
995.
Mixed modelling for QTL × environment interaction analysis 总被引:2,自引:0,他引:2
Phenotypic data for quantitative trait loci (QTL) mapping studies are typically generated at multiple environments in order
to broaden the inference space. Many aspects of the usually complex design call for a mixed modelling approach taking into
account various sources of variation, e.g., incomplete blocks, a spatial error structure, genetic correlations due to the
pedigree, and random environmental effects, including QTL × E interaction. Perhaps the most important source of random variation
is the genetic correlation across environment, which arises when the same set of lines is tested in each environment. This
correlation is likely to be positive, and ignoring it will lead to an increased rate of false positives. In this paper, we
present a mixed modelling framework for QTL mapping based on complex data from multiple environments. Our main focus is on
an appropriate modelling for the non-QTL part. The methodology will be illustrated using a barley data set from a BC2F2:5 advanced backcross trial.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
996.
B.I.G. Haussmann D.E. Hess B.V.S. Reddy S.Z. Mukuru M. Kayentao H.G. Welz H.H. Geiger 《Euphytica》2001,122(2):297-308
The parasitic weed Striga hermonthica (Del.) Benth. seriously limits sorghum [Sorghum bicolor (L.) Moench] production in Sub-Saharan Africa. As an outbreeder, S. hermonthica is highly variable with an extraordinary capacity to adapt to different hosts and environments, thereby complicating resistance
breeding. To study genotype x environment (G x E) interaction for striga resistance and grain yield, nine sorghum lines, 36
F2 populations and five local checks were grown under striga infestation at two locations in both Mali and Kenya. Mean squares
due to genotypes and G x E interaction were highly significant for both sorghum grain yield and area under striga severity
progress curve(ASVPC, a measure of striga emergence and vigor throughout the season). For grain yield, the entry x location-within-country
interaction explained most of the total G x E while for ASVPC, entry x country and entry x location-within-country interactions
were equally important. Pattern analysis (classification and ordination techniques) was applied to the environment-standardized
matrix of entry x environment means. The classification clearly distinguished Malian from Kenyan locations for ASVPC, but
not for grain yield. Performance plots for different entry groups showed differing patterns of adaptation. The ordination
biplot underlined the importance of entry x country interaction for ASVPC. The F2 derived from the cross of the striga-resistant line Framida with the striga-tolerant cultivar Seredo was the superior entry
for both grain yield and ASVPC, underlining the importance of combining resistance with tolerance in striga resistance breeding.
The observed entry x country interaction for ASVPC may be due to the entries' different reactions to climatic conditions and
putative differences in striga virulence in Mali and Kenya.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
997.
Previously, we reported that phyllochron of rice greatly fluctuated in the course of development under natural conditions. The present study was carried out to examine the phyllochron dynamics using the five near-isogenic lines (NILs) for heading time and the recurrent parent. The change of phyllochron was investigated under four different controlled conditions regarding daylength and temperature. Growth duration (days to heading) showed a large variation among different growth regimes as well as genotypes. Changes of phyllochron were evaluated in the genotypes by using a quartic polynomial regression that was well fitted to the change of phyllochron in the present controlled environments as previously observed under natural conditions. Phyllochron began to drastically increase after around the 5th phytomer order and decreased with the progress of reproductive development in similar manners under different environments. The pattern of phyllochron change varied from a flat to non-flat shape. The shape of the equation was affected by genotypes as well as daylengths and temperatures. In addition, the shape was closely related to the growth duration (days to heading) of the genotype, suggesting that the phyllochron might internally increase depending on the genotype controlling the heading date. Therefore, the present results showed that the sufficient examination of phyllochron dynamics is necessary for understanding a variation in the heading date of rice. 相似文献
998.
Yield and adaptation of hexaploid spring triticale 总被引:2,自引:0,他引:2
Summary Gains in yield and stability were analysed using grain yield data from the 8th to the 14th International Triticale Yield Nursery (ITYN) and differences in adaptation between complete and substituted triticales (X Triticosecale Wittmack) were examined. A trend of improving yield and adaptation was observed. As highly significant genotype × site interaction each year was not adequately described using regression analysis, yield stability was examined by ranking genotypes within sites and summarizing scores for individual genotypes across sites. Cluster analysis was used to study the relationships among sites and among genotypes. There was little evidence of sites grouping on a geographical basis. Grouping of genotypes showed a tendency for complete and substituted triticales to perform differently, suggesting that diversity for adaptation is maximized by utilizing both types in breeding.Progress for grain yield is compared with more spectacular gains in test weight and reasons for the different rates of improvement are postulated.Abbreviations CIMMYT
International Maize & Wheat Improvement Centre
- ITYN
International Triticale Yield Nursery
contribution from CIMMYT/Agriculture Canada (No. R-002) 相似文献
999.
Summary In breeding crop varieties for stress environments, it must be decided whether to select directly, in the presence of stress, or indirectly, in a nonstress environment. The relative effectiveness of these two strategies depends upon the genetic correlation (r
g
) between yield in stress and nonstress environments and upon heritability in each. These parameters were estimated for grain yield of 116 random oat lines grown in nonstress, P-deficient, N-deficient, and late-planted environments. Estimates of r
g
between yield in nonstress and yield in P-deficient, N-deficient, and late-planted environments were 0.52±0.24, 1.08±0.16, and 0.06±0.24, respectively. No consistent relationship between heritability and environment mean yield was observed. Direct selection in the presence of stress was predicted to be superior for yield in low-P and late-planted environments, but indirect selection in high-N environments was predicted to be as effective as direct selection in producing yield gain in low-N environments. These results confirm that neither high-yield environments nor environments in which the heritability of yield is maximized are necessarily optimum when the goal is to maximize yield gain in stress environments.Dep. of Agronomy, Iowa State Univ., Ames, IA 50011; USA, Journal Paper no. 13101. Project 2447. 相似文献
1000.
Summary Four varieties of lupins were sown at three planting dates and the level of Phomopsis leptostromiformis measured on the mature stems. When averaged over planting dates the varieties did not differ in resistance to this disease, however there were highly significant interactions between varieties and planting dates for level of disease. The implications of this result for resistance breeding to Phomopsis leptostromiformis are discussed. 相似文献