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81.
Kernel texture is an important characteristic for both the milling and the end-use quality of wheat (Triticum aestivum L.). Gene sequence variation and mutations to the two puroindoline genes (Pina and Pinb), located at the Ha locus on chromosome 5DS, account for the majority of variation in wheat kernel texture. Other factors also influence kernel texture, including effects associated with different maternal parent backgrounds. To investigate the effect of two hard puroindoline alleles in different maternal backgrounds, a population of 228 recombinant inbred lines (RILs) derived from a reciprocal cross between two wheat cultivars ID377s (Pina-D1b/Pinb-D1a) and Klasic (Pina-D1a/Pinb-D1b) were examined in two succeeding generations (F7 & F8). Kernel texture was determined using the Single Kernel Characterization System (SKCS) and the RIL puroindoline haplotype was identified by the sequence-specific PCR amplification of each gene. Analysis of variance identified a significant (P 0.001) effect of the maternal parent and puroindoline mutation on kernel texture. RILs containing the Pina-D1b mutation were significantly harder than lines containing the Pinb-D1b mutation. RILs which had Klasic as the maternal parent were significantly harder than those which had ID377s as the maternal parent. When the maternal parent and puroindoline allele were analyzed in combination, RILs derived from Klasic as the maternal parent and the Pina-D1b allele were significantly harder (P 0.001) than those containing the same allele but ID377s as the maternal parent. The same occurred for RILs containing the Pinb-D1b allele, lines with Klasic as the maternal parent were harder than lines with ID377s as the maternal parent. These results corroborate the harder phenotype of the Pina-D1b allele and indicate a significant maternally-inherited contribution to kernel texture variation.  相似文献   
82.
Flanking sequences of the puroindoline a(pinA) and puroindoline b (pinB) genes from Triticum monococcum, T. urartu, Aegilops speltoides and A. tauschii were obtained by inverse PCR. Two accessions from each of these related diploid taxa were sequenced, and the sequences compared to those of the soft hexaploid wheat cultivar `Penawawa'. As expected from the origin of the D-genome in hexaploid wheat, the highest sequence identity was observed for the A. tauschii sequences, whereas the sequences for A.speltoides were the most divergent. The promoter sequences were further analyzed for putative regulatory elements, and the possible significance of several highly conserved sequence motifs is discussed. Western blots of Triton X-114 extracted proteins separated by SDS-PAGE confirmed the accumulation of pinA and pinB gene products in the endosperm of all the germplasm lines studied. The deduced amino acid sequences for the related diploid taxa do not imply any major structural changes as compared to the wild-type T. aestivum puroindolines, and is therefore in agreement with the soft endosperm texture of these species. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
83.
OBJECTIVE: The effectiveness of geographic targeting in nutrition programmes depends largely on the degree to which malnutrition clusters within particular areas. This study investigates the extent to which the childhood nutrition indicators, stunting (height-for-age Z-score <-2) and wasting (weight-for-height Z-score <-2), are spatially clustered; this information is used to determine the implications of spatial clustering for the effectiveness of geographic targeting. DESIGN: Analysis of data from Demographic and Health Survey (DHS) results. Clustering is assessed by calculating intra-cluster correlation coefficients (ICCs). Estimating the proportion of malnourished children covered by a programme successfully targeting 10% of clusters with the highest malnutrition prevalences allows an assessment of the effectiveness of geographic targeting. SETTING: Fifty-eight DHS III (1992-1997) and DHS IV (1998-2001) reports from 46 developing countries. SUBJECTS: Pre-school children of mothers interviewed by DHS. MAIN RESULTS: The extent of clustering of nutritional status was surprisingly low (median ICC for national samples: stunting=0.054, wasting=0.032) and most countries were characterised by having an ICC <0.1--i.e. low clustering--for childhood undernutrition (91% of countries for wasting and 78% for stunting). Our assessment of the effectiveness of geographic targeting showed that coverage was better for wasting than for stunting; for wasting, 23% of countries would achieve less than 20% coverage, compared with 76% of countries achieving less than 20% coverage for stunting. Coverage is dependent on the overall prevalence of malnutrition and the ICC. CONCLUSIONS: Childhood nutritional status is determined at the household, or even individual, level; nutrition programmes that are geographically targeted may result in high levels of under-coverage and leakage, thereby compromising their cost-effectiveness; the lack of clustering questions the appropriateness of current nutrition interventions.  相似文献   
84.
In the realm of plant genomics, metabolic profiling has become a valuable tool with which to assess the effect of genetic and/or environmental factors on plant development. This paper reports the first application of metabolic profiling on differentiating xylem tissue of loblolly pine. A protocol is presented for the analysis of loblolly pine xylem tissue. The effects of sample preparation, extraction, and derivatization on the corresponding metabolite profiles and yields have been investigated and are reported. Gas chromatography-mass spectroscopy has been used to quantify >60 polar and lipophilic metabolites from wood-forming tissue. It was possible to assign chemical structures to approximately half of these compounds. Comparison of six loblolly pine genotypes, three high cellulose (50-52%) and three medium (45-48%) cellulose, showed distinct metabolic profiles. Principal component analysis enabled the assignment of metabolic phenotypes using these large data sets. Metabolic phenotype clustering occurred in which the three high-cellulose genotypes were segregated from the medium-cellulose genotypes. These results demonstrate the use of metabolic profiling for the study of wood-forming tissue and as a tool in functional genomics.  相似文献   
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87.
Soft-bodied marine faunas from the Lower and Middle Cambrian, exemplified by the Burgess Shale of British Columbia, are a key component in understanding the major adaptive radiations at the beginning of the Phanerozoic ("Cambrian explosion"). These faunas have a widespread distribution, and many taxa have pronounced longevity. Among the components appear to be survivors of the preceding Ediacaran assemblages and a suite of bizarre forms that give unexpected insights into morphological diversification. Microevolutionary processes, however, seem adequate to account for this radiation, and the macroevolutionary patterns that set the seal on Phanerozoic life are contingent on random extinctions. They weeded out the morphological spectrum and permitted rediversification among surviving clades. Although the predictability of which clades will play in successive acts of the Phanerozoic theater is low, at least the outlines of the underlying ecological plot are already clear from the opening of the drama.  相似文献   
88.
The Mars Exploration Rover (MER), Opportunity, showed that layered sulfate deposits in Meridiani Planum formed during a period of rising acidic ground water. Crystalline hematite spherules formed in the deposits as a consequence of aqueous alteration and were concentrated on the surface as a lag deposit as wind eroded the softer sulfate rocks. On the basis of Mars Express Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité (OMEGA) orbital data, we demonstrate that crystalline hematite deposits are associated with layered sulfates in other areas on Mars, implying that Meridiani-like ground water systems were indeed widespread and representative of an extensive acid sulfate aqueous system.  相似文献   
89.
The temperature- and concentration-dependent resistivities of annealed CaxC(60) and SrxC(60) films were measured near room temperature. Resistivity minima were observed at x = 2 and 5. The resistivities of these films were rho(min) approximately 1 ohm-centimeter for x = 2 and rho(min) approximately 10(-2) ohm-centimeter for x = 5. This latter value is comparable to the resistivities found in similar experiments on K(3)C(60) films. There is a maximum in the resistivity between x = 2 and 3, and another at x approximately 7. The conductivity is activated over the whole range of compositions, and the activation energy scales with the logarithm of the resistivity. The results suggest that the conductivity and superconductivity observed in Ca(5)C(60) are associated with the population of bands derived from the t(1g) level of C(6O).  相似文献   
90.
Circadian periodicity in susceptibility to lidocaine hydrochloride   总被引:1,自引:0,他引:1  
Separate groups of mice standardized in an alternating 12-hour-light,12-hour-dark regimen were treated with lidocaine hydrochloride every 3 hours over a 24-hour period. The results indicate a quantitative circadian periodicity with maximal convulsant activity at 2100 hours which was approximately a fourteen fold increase over the values observed at 1500 hours.  相似文献   
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