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101.
Do we expect natural selection to produce rational behaviour? 总被引:3,自引:0,他引:3
Houston AI McNamara JM Steer MD 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2007,362(1485):1531-1543
We expect that natural selection should result in behavioural rules which perform well; however, animals (including humans) sometimes make bad decisions. Researchers account for these with a variety of explanations; we concentrate on two of them. One explanation is that the outcome is a side effect; what matters is how a rule performs (in terms of reproductive success). Several rules may perform well in the environment in which they have evolved, but their performance may differ in a 'new' environment (e.g. the laboratory). Some rules may perform very badly in this environment. We use the debate about whether animals follow the matching law rather than maximizing their gains as an illustration. Another possibility is that we were wrong about what is optimal. Here, the general idea is that the setting in which optimal decisions are investigated is too simple and may not include elements that add extra degrees of freedom to the situation. 相似文献
102.
Brown T Taherbhai Z Sexton J Sutterfield A Turlington M Jones J Stallings L Stewart M Buchmueller K Mackay H O'hare C Kluza J Nguyen B Wilson D Lee M Hartley JA 《Bioorganic & medicinal chemistry》2007,15(1):474-483
Five polyamide derivatives with rationally modified C-terminus moieties were synthesized and their DNA binding specificity and affinity determined. A convergent approach was employed to synthesize polyamides containing an alkylaminopiperazine (4 and 5), a truncated piperazine (6), or an alkyldiamino-C-terminus moiety (7 and 8) with two specific objectives: to investigate the effects of number of potential cationic centers and steric bulk at the C-terminus. CD studies confirmed that compounds 4, 5, 7, and 8 bind in the minor groove of DNA. The alkylpiperazine containing compounds (4 and 5) showed only moderate binding to DNA with DeltaT(m) values of 2.8 and 8.3 degrees C with their cognate sequence, respectively. The alkyldiamino compounds (7 and 8) were more impressive producing a DeltaT(m) of >17 and >22 degrees C, respectively. Compound 6 (truncated piperazine) did not stabilize its cognate DNA sequence. Footprints were observed for all compounds (except compound 6) with their cognate DNA sequence using DNase I footprinting, with compound 7 producing a footprint of 0.1 microM at the expected 5'-ACGCGT-3' site. SPR analysis of compound 7 binding to 5'-ACGCGT-3', 5'-ACCGGT-3', and 5'-AAATTT-3' produced binding affinities of 2.2x10(6), 3.3x10(5), and 1x10(5)M(-1), respectively, indicating a preference for its cognate sequence of 5'-ACGCGT-3'. These results are in good agreement with the footprinting data. The results indicate that steric crowding at the C-terminus is important with respect to binding. However, the number of cationic centers within the molecule may also play a role. The alkyldiamino-containing compounds (7 and 8) warrant further investigation in the field of polyamide research. 相似文献
103.
Welsh TN Hubbard S Mitchell CM Mesiano S Zarzycki PK Zakar T 《Prostaglandins & other lipid mediators》2007,83(4):304-310
The primary prostaglandins PGE(2) and PGF(2 alpha) are metabolized in tissues by a series of enzymatic and non-enzymatic reactions. To measure metabolic rates and individual reaction rates it is necessary to extract the parent prostaglandins and metabolites before the separation and quantification of each compound is achieved. Here we have established and optimized a solid phase extraction (SPE) procedure to recover PGE(2), PGF(2 alpha) and their six enzymatic and non-enzymatic tissue metabolites from aqueous solutions including urine, plasma and tissue homogenate. We have used octadecyl-bonded silica gel as the stationary phase and methanol-water mixtures as binary mobile phases. The volumes and concentrations of the washing and elution solutions were optimized individually for each PG. Recoveries of all PG standards were quantitative except for PGEM, which was recovered at 80% efficiency. Biological matrix components interfered with the extraction in a PG- and matrix-specific fashion. Inclusion of 1% formic acid in the loading mixture raised recoveries from urine, plasma and tissue homogenate to >or=90%. This SPE method is the first that has been optimized by systematic elution studies for PGE(2), PGF(2 alpha) and the complement of their tissue metabolites. The procedure is simple, robust and can serve as an effective pre-purification step before downstream separation and quantification of each tissue metabolite of PGE(2) and PGF(2 alpha) from complex biological matrices. 相似文献
104.
The morphogenetic events leading to the transendothelial passage of lymphoid and tumoral cells are analyzed in light of a very recent and global theory of intercellular communication designated as the Triune Information Network (TIN). The TIN system is based on the assumption that cell-cell interactions primarily occur through cell surface informations or topobiological procesess, whose mechanisms rely upon expression of adhesion molecules, and are regulated by an array of locally-borne (autocrine/paracrine signals and autonomic inputs) and distantly-borne (endocrine secretions) messages. The final aim of the TIN is to control homeostatic functions crucial for the organism survival, like morphogenesis. Knowledge of the TIN signals involved in lymphoid and tumoral cell intravasation might offer a new perspetive to study the mechanisms of tumor immunity. Recognition of tumor target cells by immune cytotoxic effectors, in fact, can be considered a notable case of TIN-mediated cell to cell interaction. In particular, Natural Killer (NK) cells play a role in the cell-mediated control of tumor growth and metastatic spreading. Cell targeting and killing are dependent on the different NK cell receptors and on the efficacy of NK cells after cytokine and monoclonal antibody administration in cancer therapy. Since efficacy of NK cell-based immunotheraphy has been proven in KIR-mismatch regimens or in TRAIL-dependent apoptosis, the ability to manipulate the balance of activating and inhibitory receptors on NK cells and of their cognate ligands as well as the sensitivity of tumor cells to apoptosis, opens new perspectives for NK cell based immunotherapy. 相似文献
105.
Snake scales contain specialized hard keratins (beta-keratins) and alpha- or cyto-keratins in their epidermis. The number, isoelectric point, and the evolution of these proteins in snakes and their similarity with those of other vertebrates are not known. In the present study, alpha- and beta-keratins of snake molts and of the whole epidermis have been studied by using two-dimensional electrophoresis and immunocytochemistry. Specific keratins in snake epidermis have been identified by using antibodies that recognize acidic and basic cytokeratins and avian or lizard scale beta-keratin. Alpha keratins of 40-70 kDa and isoelectric point (pI) at 4.5-7.0 are present in molts. The study suggests that cytokeratins in snakes are acidic or neutral, in contrast to mammals and birds where basic keratins are also present. Beta keratins of 10-15 kDa and a pI of 6.5-8.5 are found in molts. Some beta-keratins appear as basic proteins (pI 8.2) comparable to those present in the epidermis of other reptiles. Some basic "beta-keratins" associate with cytokeratins as matrix proteins and replace cytokeratins forming the corneous material of the mature beta-layer of snake scales, as in other reptiles. The study also suggests that more forms of beta-keratins (more than three different types) are present in the epidermis of snakes. 相似文献
106.
Do Insectivorous Birds use Volatile Organic Compounds from Plants as Olfactory Foraging Cues? Three Experimental Tests 下载免费PDF全文
Tuuli‐Marjaana Koski Toni Laaksonen Elina Mäntylä Suvi Ruuskanen Tao Li Patricia Sarai Girón‐Calva Liisa Huttunen James D. Blande Jarmo K. Holopainen Tero Klemola 《Ethology : formerly Zeitschrift fur Tierpsychologie》2015,121(12):1131-1144
Some insectivorous birds orient towards insect‐defoliated trees even when they do not see the foliar damage or the herbivores. There are, however, only a few studies that have examined the mechanisms behind this foraging behaviour. Previous studies suggest that birds can use olfactory foraging cues (e.g. volatile organic compounds (VOCs) emitted by defoliated plants), indirect visual cues or a combination of the two sensory cues. VOCs from insect‐defoliated plants are known to attract natural enemies of herbivores, and researchers have hypothesized that VOCs could also act as olfactory foraging cues for birds. We conducted three experiments across a range of spatial scales to test this hypothesis. In each experiment, birds were presented with olfactory cues and their behavioural responses or foraging outcomes were observed. In the first experiment, two different VOC blends, designed to simulate the volatile emissions of mountain birch (Betula pubescens ssp. czerepanovii) after defoliation by autumnal moth (Epirrita autumnata) larvae, were used in behavioural experiments in aviaries with pied flycatchers (Ficedula hypoleuca). The second experiment was a field‐based trial of bird foraging efficiency; the same VOC blends were applied to mountain birches, silver birches (B. pendula) and European white birches (B. pubescens) with plasticine larvae attached to the trees to serve as artificial prey for birds and provide a means to monitor predation rate. In the third experiment, the attractiveness of silver birch saplings defoliated by autumnal moth larvae versus intact controls was tested with great tits (Parus major) and blue tits (Cyanistes caeruleus) in an aviary. Birds did not orient towards either artificial or real trees with VOC supplements or towards herbivore‐damaged saplings when these saplings and undamaged alternatives were hidden from view. These findings do not support the hypothesis that olfactory foraging cues are necessary in the attraction of birds to herbivore‐damaged trees. 相似文献
107.
Transcriptome analysis of cyclic AMP‐dependent protein kinase A–regulated genes reveals the production of the novel natural compound fumipyrrole by Aspergillus fumigatus 下载免费PDF全文
108.
Fecundity selection does not vary along a large geographical cline of trait means in a passerine bird 下载免费PDF全文
Päivi M. Sirkiä Peter Adamík Alexandr V. Artemyev Eugen Belskii Christiaan Both Stanislav Bureš Malcolm Burgess Andrey V. Bushuev Jukka T. Forsman Vladimir Grinkov Dieter Hoffmann Antero Järvinen Miroslav Král Indrikis Krams Helene M. Lampe Juan Moreno Marko Mägi Andreas Nord Jaime Potti Pierre‐Alain Ravussin Leonid Sokolov Toni Laaksonen 《Biological journal of the Linnean Society. Linnean Society of London》2015,114(4):808-827
Local environmental and ecological conditions are commonly expected to result in local adaptation, although there are few examples of variation in phenotypic selection across continent‐wide spatial scales. We collected standardized data on selection with respect to the highly variable plumage coloration of pied flycatcher (Ficedula hypoleuca Pall.) males from 17 populations across the species' breeding range. The observed selection on multiple male coloration traits via the annual number of fledged young was generally relatively weak. The main aim of the present study, however, was to examine whether the current directional selection estimates are associated with distance to the sympatric area with the collared flycatcher (Ficedula albicollis Temminck), a sister species with which the pied flycatcher is showing character displacement. This pattern was expected because plumage traits in male pied flycatchers are changing with the distance to these areas of sympatry. However, we did not find such a pattern in current selection on coloration. There were no associations between current directional selection on ornamentation and latitude or longitude either. Interestingly, current selection on coloration traits was not associated with the observed mean plumage traits of the populations. Thus, there do not appear to be geographical gradients in current directional fecundity selection on male plumage ornamentation. The results of the present study do not support the idea that constant patterns in directional fecundity selection would play a major role in the maintenance of coloration among populations in this species. By contrast, the tendency for relatively weak mosaic‐like variation in selection among populations could reflect just a snapshot of temporally variable, potentially environment‐dependent, selection, as suggested by other studies in this system. Such fine‐grained variable selection coupled with gene flow could maintain extensive phenotypic variation across populations. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 808–827. 相似文献
109.
Daniel F. Carlson Aron M. Geurts John R. Garbe Chang-Won Park Artur Rangel-Filho Scott M. O’Grady Howard J. Jacob Clifford J. Steer David A. Largaespada Scott C. Fahrenkrug 《Transgenic research》2011,20(1):29-45
Heightened interest in relevant models for human disease increases the need for improved methods for germline transgenesis.
We describe a significant improvement in the creation of transgenic laboratory mice and rats by chemical modification of Sleeping Beauty transposons. Germline transgenesis in mice and rats was significantly enhanced by in vitro cytosine-phosphodiester-guanine
methylation of transposons prior to injection. Heritability of transgene alleles was also greater from founder mice generated
with methylated versus non-methylated transposon. The artificial methylation was reprogrammed in the early embryo, leading
to founders that express the transgenes. We also noted differences in transgene insertion number and structure (single-insert
versus concatemer) based on the influence of methylation and plasmid conformation (linear versus supercoiled), with supercoiled
substrate resulting in efficient transpositional transgenesis (TnT) with near elimination of concatemer insertion. Combined,
these substrate modifications resulted in increases in both the frequency of transgenic founders and the number of transgenes
per founder, significantly elevating the number of potential transgenic lines. Given its simplicity, versatility and high
efficiency, TnT with enhanced Sleeping Beauty components represents a compelling non-viral approach to modifying the mammalian germline. 相似文献
110.
David Coulibaly-N'Golo Bernard Allali Stéphane K. Kouassi Elisabeth Fichet-Calvet Beate Becker-Ziaja Toni Rieger Stephan ?lschl?ger Hernri Dosso Christiane Denys Jan ter Meulen Chantal Akoua-Koffi Stephan Günther 《PloS one》2011,6(6)
This study aimed to identify new arenaviruses and gather insights in the evolution of arenaviruses in Africa. During 2003 through 2005, 1,228 small mammals representing 14 different genera were trapped in 9 villages in south, east, and middle west of Côte d''Ivoire. Specimens were screened by pan-Old World arenavirus RT-PCRs targeting S and L RNA segments as well as immunofluorescence assay. Sequences of two novel tentative species of the family Arenaviridae, Menekre and Gbagroube virus, were detected in Hylomyscus sp. and Mus (Nannomys) setulosus, respectively. Arenavirus infection of Mus (Nannomys) setulosus was also demonstrated by serological testing. Lassa virus was not found, although 60% of the captured animals were Mastomys natalensis. Complete S RNA and partial L RNA sequences of the novel viruses were recovered from the rodent specimens and subjected to phylogenetic analysis. Gbagroube virus is a closely related sister taxon of Lassa virus, while Menekre virus clusters with the Ippy/Mobala/Mopeia virus complex. Reconstruction of possible virus–host co-phylogeny scenarios suggests that, within the African continent, signatures of co-evolution might have been obliterated by multiple host-switching events. 相似文献