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131.
A. Gallais 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1988,75(4):625-627
Summary A method is presented to estimate, from a two-factor crossing design including self-fertilization, mean and variance of lines and hybrids that can be derived from a random mating population. The derivation is only valid in the absence of epistasis. From such an estimation, it is possible to derive the expected value of the best lines and of the best hybrids that can be derived from a population. 相似文献
132.
A genetic disease observed in certain Quarter horses is hyperkalaemic periodic paralysis (HYPP). This disease causes attacks of paralysis which can be induced by ingestion of potassium. Recent studies have shown that HYPP in humans is due to single base changes within the adult skeletal muscle sodium channel gene. A large Quarter horse pedigree segregating dominant HYPP was studied to determine if mutations of the sodium channel gene are similarly responsible for HYPP in horses. We used cross-species, PCR-mediated, cDNA cloning and sequencing of the horse adult skeletal muscle sodium channel alpha-subunit gene to identify a polymorphism, and then used this polymorphism to see if the horse sodium channel gene was genetically linked to HYPP in horses. The sodium channel gene was indeed found to be tightly linked to HYPP (LOD = 2.7, theta = 0). Our results suggest that HYPP in horses involves the same gene as the clinically similar human disease, and indicates that these are homologous disorders. The future identification of the specific sodium channel mutation causing HYPP in Quarter horses will permit the development of accurate molecular diagnostics of this condition, as has been recently shown for humans. 相似文献
133.
AYODELE S. JEGEDE 《Developing world bioethics》2009,9(3):128-137
Africa is a continent in transition amidst a revival of cultural practices. Over previous years the continent was robbed of the benefits of medical advances by unfounded cultural practices surrounding its cultural heritage. In a fast moving field like genetic screening, discussions of social and policy aspects frequently need to take place at an early stage to avoid the dilemma encountered by Western medicine. This paper, examines the potential challenges to genetic screening in Africa. It discusses how cultural practices may affect genetic screening. It views genomics science as a culture which is trying to diffuse into another one. It argues that understanding the existing culture will help the diffusion process. The paper emphasizes the importance of genetic screening for Africa, by assessing the current level of burden of diseases in the continent and shows its role in reducing disease prevalence. The paper identifies and discusses the cultural challenges that are likely to confront genetic screening on the continent, such as the worldview, rituals and taboos, polygyny, culture of son preference and so on. It also discusses cultural practices that may promote the science such as inheritance practices, spouse selection practices and naming patterns. Factors driving the cultural challenges are identified and discussed, such as socialization process, patriarchy, gender, belief system and so on. Finally, the paper discusses the way forward and highlights the ethical considerations of doing genetic screening on the continent. However, the paper also recognizes that African culture is not monolithic and therefore makes a case for exceptions. 相似文献
134.
A.J. O’Neill 《Letters in applied microbiology》2010,51(3):358-361
Aims: To provide comparative genome sequence data for two related model strains of Staphylococcus aureus (SH1000 and 8325‐4) that are used extensively in laboratory research. Methods and Results: Comparative genome sequencing was used to identify genetic differences between Staph. aureus SH1000 and the fully genome‐sequenced ancestral strain, Staph. aureus NCTC 8325. PCR amplification and DNA sequencing were employed to determine which of the genetic polymorphisms identified were also present in Staph. aureus 8325‐4, a direct derivative of 8325 and the parent strain of SH1000. Aside from known genetic differences between these strains, Staph. aureus SH1000 harboured 15 single‐nucleotide polymorphisms compared with 8325 (of which 12 were also found in 8325‐4), and a 63‐bp deletion upstream of the spa gene not present in either 8325 or 8325‐4. Conclusions: Staphylococcus aureus SH1000 and 8325‐4 contain a number of genetic polymorphisms relative to the progenitor strain of the lineage (8325) and to each other. Significance and Impact of the Study: The comparative genome sequences of SH1000 and 8325‐4 presented here define the genotypes of two key strains in staphylococcal laboratory research and reveal genetic polymorphisms that may impact their phenotypic properties. 相似文献
135.
《遗传学报》2020,47(10):637-649
The long history of cultivation and breeding has left a variety of footprints in the genomes of Asian cultivated rice (Oryza sativa L.). In this study, we focus on two types of genomic footprints, introgression and differentiation, in a population of more than 1200 Chinese rice accessions. We found that a Xian/indica and a temperate Geng/japonica accession respectively contained an average of 19.3-Mb and 6.8-Mb alien introgressed chromosomal segments, of which many contained functional sequence variants, quantitative trait loci, or genes controlling flowering, grain, and resistance traits. Notably, we found most introgressions, including the known heterotic loci Hd3a and TAC1, were distributed differentially between the female and male parents of three-line indica hybrid rice, indicating their potential contribution to heterosis. We also found many differentiated regions between subgroups within a subpopulation contained agronomically important loci, such as DTH7, Hd1 for heading date, and qCT7 for cold tolerance, providing new candidates for studying local adaptation or heterosis. Tracing these footprints allows us to better understand the genetic exchange or differentiation underlying agronomic traits in modern Chinese rice cultivars. These findings also provide potential targets for rice genetic research and breeding. 相似文献
136.
137.
Tropospheric ozone (O3) is an important stressor in natural ecosystems, with well‐documented impacts on soils, biota and ecological processes. The effects of O3 on individual plants and processes scale up through the ecosystem through effects on carbon, nutrient and hydrologic dynamics. Ozone effects on individual species and their associated microflora and fauna cascade through the ecosystem to the landscape level. Systematic injury surveys demonstrate that foliar injury occurs on sensitive species throughout the globe. However, deleterious impacts on plant carbon, water and nutrient balance can also occur without visible injury. Because sensitivity to O3 may follow coarse physiognomic plant classes (in general, herbaceous crops are more sensitive than deciduous woody plants, grasses and conifers), the task still remains to use stomatal O3 uptake to assess class and species’ sensitivity. Investigations of the radial growth of mature trees, in combination with data from many controlled studies with seedlings, suggest that ambient O3 reduces growth of mature trees in some locations. Models based on tree physiology and forest stand dynamics suggest that modest effects of O3 on growth may accumulate over time, other stresses (prolonged drought, excess nitrogen deposition) may exacerbate the direct effects of O3 on tree growth, and competitive interactions among species may be altered. Ozone exposure over decades may be altering the species composition of forests currently, and as fossil fuel combustion products generate more O3 than deteriorates in the atmosphere, into the future as well. 相似文献
138.
139.
Here, we study the evolution of specialization using realistic computer simulations of bacteria that secrete two public goods in a dynamic fluid. Through this first‐principles approach, we find physical factors such as diffusion, flow patterns and decay rates are as influential as fitness economics in governing the evolution of community structure, to the extent that when mechanical factors are taken into account, (a) generalist communities can resist becoming specialists despite the invasion fitness of specialization; (b) generalist and specialists can both resist cheaters despite the invasion fitness of free‐riding; and (c) multiple community structures can coexist despite the opposing force of competitive exclusion. Our results emphasize the role of spatial assortment and physical forces on niche partitioning and the evolution of diverse community structures. 相似文献
140.
Thibaut Capblancq Xavier Morin Maya Gueguen Julien Renaud Stphane Lobreaux Eric Bazin 《Journal of evolutionary biology》2020,33(6):783-796
Local adaptation patterns have been found in many plants and animals, highlighting the genetic heterogeneity of species along their range of distribution. In the next decades, global warming is predicted to induce a change in the selective pressures that drive this adaptive variation, forcing a reshuffling of the underlying adaptive allele distributions. For species with low dispersion capacity and long generation time such as trees, the rapidity of the change could impede the migration of beneficial alleles and lower their capacity to track the changing environment. Identifying the main selective pressures driving the adaptive genetic variation is thus necessary when investigating species capacity to respond to global warming. In this study, we investigate the adaptive landscape of Fagus sylvatica along a gradient of populations in the French Alps. Using a double‐digest restriction‐site‐associated DNA (ddRAD) sequencing approach, we identified 7,000 SNPs from 570 individuals across 36 different sites. A redundancy analysis (RDA)‐derived method allowed us to identify several SNPs that were strongly associated with climatic gradients; moreover, we defined the primary selective gradients along the natural populations of F. sylvatica in the Alps. Strong effects of elevation and humidity, which contrast north‐western and south‐eastern site, were found and were believed to be important drivers of genetic adaptation. Finally, simulations of future genetic landscapes that used these findings allowed identifying populations at risk for F. sylvatica in the Alps, which could be helpful for future management plans. 相似文献