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191.
Kin recognition, the ability to detect relatives, is important for cooperation, altruism and also inbreeding avoidance. A large body of research on kin recognition mechanisms exists for vertebrates and insects, while little is known for other arthropod taxa. In spiders, nepotism has been reported in social and solitary species. However, there are very few examples of kin discrimination in a mating context, one coming from the orb-weaver Argiope bruennichi. Owing to effective mating plugs and high rates of sexual cannibalism, both sexes of A. bruennichi are limited to a maximum of two copulations. Males surviving their first copulation can either re-mate with the current female (monopolizing paternity) or leave and search for another. Mating experiments have shown that males readily mate with sisters but are more likely to leave after one short copulation as compared with unrelated females, allowing them to search for another mate. Here, we ask whether the observed behaviour is based on chemical cues. We detected family-specific cuticular profiles that qualify as kin recognition cues. Moreover, correlations in the relative amounts of some of the detected substances between sexes within families indicate that kin recognition is likely based on subsets of cuticular substances, rather than entire profiles. 相似文献
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de Giuseppe PO Ullah A Silva DT Gremski LH Wille AC Chaves Moreira D Ribeiro AS Chaim OM Murakami MT Veiga SS Arni RK 《Biochemical and biophysical research communications》2011,409(4):6064-627
Phospholipases D (PLDs) are principally responsible for the local and systemic effects of Loxosceles envenomation including dermonecrosis and hemolysis. Despite their clinical relevance in loxoscelism, to date, only the SMase I from Loxosceles laeta, a class I member, has been structurally characterized. The crystal structure of a class II member from Loxosceles intermedia venom has been determined at 1.7 Å resolution. Structural comparison to the class I member showed that the presence of an additional disulphide bridge which links the catalytic loop to the flexible loop significantly changes the volume and shape of the catalytic cleft. An examination of the crystal structures of PLD homologues in the presence of low molecular weight compounds at their active sites suggests the existence of a ligand-dependent rotamer conformation of the highly conserved residue Trp230 (equivalent to Trp192 in the glycerophosphodiester phosphodiesterase from Thermus thermophofilus, PDB code: 1VD6) indicating its role in substrate binding in both enzymes. Sequence and structural analyses suggest that the reduced sphingomyelinase activity observed in some class IIb PLDs is probably due to point mutations which lead to a different substrate preference. 相似文献
196.
M.‐L. Johnson P. M. Schenk B. W. Cribb C. Moore L. E. Perkins M. P. Zalucki 《Entomologia Experimentalis et Applicata》2011,141(1):78-87
Theory and recent literature suggest strong effects of induced plant defences in some plant herbivore systems. Few have studied behavioural effects on intact plants. Differences in foraging behaviour as well as weight gain were determined for first instar Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) on Arabidopsis thaliana (L.) Heynh. (Brassicaceae) mutant and wild type plants, non‐primed, or primed by herbivore feeding or methyl jasmonate. The differences in feeding were primarily in the length of feeding time as opposed to the area fed on, feeding location, or frequency. More larvae dispersed from plants after priming by mite feeding than dispersed after caterpillar feeding. Other behavioural activities such as resting were not significantly affected. Early instars gained less weight feeding on ein2 (ethylene insensitive) mutant, but there was no difference in weight gain between larvae feeding on induced and non‐induced plants of the same type. We concluded that there are fitness consequences for neonates of the generalist H. armigera after feeding on induced plant tissues in some cases, and that distinct changes in behaviour are recognisable both at the fine scale and at grosser levels (dispersal). However, these changes are more subtle than might be expected. 相似文献
197.
Ettore RANDI 《Mammal Review》2011,41(2):99-111
- 1 The wolf Canis lupus, the most widespread of the four species of large carnivores in Europe, after centuries of population decline and eradication, is now recovering in many countries. Wolves contribute to regulating prey–predator dynamics and interact with human activities, mainly livestock farming and ungulate hunting. Although wolves are protected in most European countries, illegal or incidental killing is widespread.
- 2 Wolf populations do not show any apparent phylogeographic structuring worldwide. Molecular and morphological studies of historical samples showed evidence of wolf ecomorph extinctions, coinciding with the great Pleistocene faunal turnover.
- 3 Extant populations show recurrent long‐range dispersal during cycles of expansion and recolonization. Demographically stable populations, in contrast, seem to be characterized by very limited gene flow.
- 4 Despite the potential for dispersal and ecological flexibility, landscape genetic approaches have demonstrated the existence of genetically distinct wolf populations, which originated through habitat and prey specializations.
- 5 Small isolated wolf populations may suffer from inbreeding depression, although selection for heterozygotes and the rescue effect can foster rapid population recovery. Population structure and dynamics is efficiently monitored by non‐invasive genetic methods, which are also useful to identify wolf × dogCanis lupus familiaris hybridization.
- 6 Despite technical advances and a better knowledge of wolf biology, wolf conservation is largely dependent on humans, and on the solution of conflicts with stakeholders.
198.
Spermatogenesis has long been a major research area in understanding the development of living organisms. In vertebrates, sperm is produced along the wall of the seminiferous tubules, leaving spermatogonia in the outermost layer, which undergo cell division and differentiation. However, sperm in many invertebrates is developed in a testicular cyst, which contains germ cells at the same developmental stages. On the contrary, in spiders, it is very difficult to count the exact number of cells in a cyst, since each spermatid gets transformed to a round sperm ball within the cyst through the flagellar coiling process. Therefore, in this study, we applied a 3D rendering technique to analyze the exact number of germ cells per cyst in spiders. For image processing and reconstruction, serial section images were scanned and reconstructed into 3D images. Upon successful 3‐dimensional reconstruction of testicular cysts, the exact number of germ cells produced from a single cyst appeared to be 64, 26 which indicates that a spider spermatogonium undergoes 6 cell divisions to produce spermatozoa. 相似文献
199.
Nicola Weichert Valeska Hauptmann Matthias Menzel Kai Schallau Philip Gunkel Thomas C. Hertel Markus Pietzsch Uwe Spohn Udo Conrad 《Plant biotechnology journal》2014,12(2):265-275
In the last two decades it was shown that plants have a great potential for production of specific heterologous proteins. But high cost and inefficient downstream processing are a main technical bottleneck for the broader use of plant‐based production technology especially for protein‐based products, for technical use as fibres or biodegradable plastics and also for medical applications. High‐performance fibres from recombinant spider silks are, therefore, a prominent example. Spiders developed rather different silk materials that are based on proteins. These spider silks show excellent properties in terms of elasticity and toughness. Natural spider silk proteins have a very high molecular weight, and it is precisely this property which is thought to give them their strength. Transgenic plants were generated to produce ELPylated recombinant spider silk derivatives. These fusion proteins were purified by Inverse Transition Cycling (ITC) and enzymatically multimerized with transglutaminase in vitro. Layers produced by casting monomers and multimers were characterized using atomic force microscopy (AFM) and AFM‐based nanoindentation. The layered multimers formed by mixing lysine‐ and glutamine‐tagged monomers were associated with the highest elastic penetration modulus. 相似文献
200.
Oscar Ramirez I?igo Olalde Jonas Berglund Belen Lorente-Galdos Jessica Hernandez-Rodriguez Javier Quilez Matthew T Webster Robert K Wayne Carles Lalueza-Fox Carles Vilà Tomas Marques-Bonet 《BMC genomics》2014,15(1)