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151.
Journal of Mathematical Biology - A set of axioms is formulated characterizing ecologically plausible community dynamics. Using these axioms, it is proved that the transients following an invasion... 相似文献
152.
Eliana Buenaventura Krzysztof Szpila Brian K. Cassel Brian M. Wiegmann Thomas Pape 《Systematic Entomology》2020,45(2):281-301
Sarcophagidae is one of the most species-rich families within the superfamily Oestroidea. This diversity is usually represented by three lineages: Miltogramminae, Paramacronychiinae and Sarcophaginae. Historically, the phylogenetic relationships among these lineages have been elusive, due to poorly supported hypotheses or small taxon sets, or both. This study provides a dramatic increase in molecular data, more balanced sampling of all three lineages from all biogeographical regions and a reassessment of morphological characters using scanning electron microscopy in the most comprehensive assessment of subfamily-level phylogeny in Sarcophagidae to date. This analysis of the largest molecular dataset ever produced for a phylogenetic analysis of a fly lineage, with 950 loci from anchored hybrid enrichment comprising 435 930 bp from 101 species, revealed Paramacronychiinae as sister to Miltogramminae, not to Sarcophaginae, as suggested by adult morphology. Maximum likelihood analysis produced a well-supported topology, with 91% of the nodes receiving strong bootstrap proportions (> 97%). In contrast to the molecular data, three out of nine morphological characters studied point to a sister-group relationship of (Sarcophaginae + Paramacronychiinae) and the remaining six characters are either silent on subfamily relationships or in need of further study. Re-examination of morphological structures provides new insights into the evolution of male genitalic traits within Sarcophagidae and highlights their convergence producing conflicting phylogenetic signal. Our phylogeny reconciles older and widely used systems of classification with tree-based thinking and sets up a classification of flesh flies that is more aligned with their evolutionary history. 相似文献
153.
Julia S. Markl Werner E. G. Müller Dayane Sereno Tarek A. Elkhooly Maria Kokkinopoulou Johan Gardères Frank Depoix Matthias Wiens 《Biotechnology and bioengineering》2020,117(6):1789-1804
During evolution, sponges (Porifera) have honed the genetic toolbox and biosynthetic mechanisms for the fabrication of siliceous skeletal components (spicules). Spicules carry a protein scaffold embedded within biogenic silica (biosilica) and feature an amazing range of optical, structural, and mechanical properties. Thus, it is tempting to explore the low-energy synthetic pathways of spiculogenesis for the fabrication of innovative hybrid materials. In this synthetic biology approach, the uptake of multifunctional nonbiogenic nanoparticles (fluorescent, superparamagnetic) by spicule-forming cells of bioreactor-cultivated sponge primmorphs provides access to spiculogenesis. The ingested nanoparticles were detected within intracellular vesicles resembling silicasomes (silica-rich cellular compartments) and as cytosolic clusters where they lent primmorphs fluorescent/magnetic properties. During spiculogenesis, the nanoparticles initially formed an incomplete layer around juvenile, intracellular spicules. In the mature, extracellular spicules the nanoparticles were densely arranged as a surface layer that rendered the resulting composite fluorescent and magnetic. By branching off the conventional route of solid-state materials synthesis under harsh conditions, a new pathway has been opened to a versatile platform that allows adding functionalities to growing spicules as templates in living cells, using nonbiogenic nanoscale building blocks with multiple functionalities. The magnet-assisted alignment renders this composite with its fluorescent/magnetic properties potentially suitable for application in biooptoelectronics and microelectronics (e.g., microscale on-chip waveguides for applications of optical detection and sensing). 相似文献
154.
155.
Indrek Saar Johan Runesson Jaak Järv Kaido Kurrikoff Ülo Langel 《Neurochemical research》2013,38(2):398-404
Neuropeptide galanin and its three receptors, galanin receptor type 1–galanin receptor type 3, are known to be involved in the regulation of numerous psychological processes, including depression. Studies have suggested that stimulation of galanin receptor type 2 (GalR2) leads to attenuation of the depression-like behavior in animals. However, due to the lack of highly selective galanin subtype specific ligands the involvement of different receptors in depression-like behavior is yet not fully known. In the present study we introduce a novel GalR2 selective agonist and demonstrate its ability to produce actions consistent with theorized GalR2 functions and analogous to that of the anti-depressant, imipramine. 相似文献
156.
Markus W. Germann Bernd W. Kalisch Johan H. van de Sande 《Journal of biomolecular structure & dynamics》2013,31(6):953-962
Abstract Oligodeoxyribonucleotides containing dA·dU base combinations were shown to form parallel stranded DNA. CD spectra and hyperchromicity profiles provide evidence that the structure is very similar to that of a related parallel stranded dA·oligomer. Thermal denaturation studies show that these parallel dAdU sequences are significantly less stable than their dA·analogues in either antiparallel or parallel stranded orientations. The stabilizing effect of the 5- methyl group is similar for parallel and antiparallel sequences. The minor groove binding drug Hoechst 33258 binds with similar affinity to APS dA·and APS dA·dU sequences. However, binding to the PS dA·hairpin is significantly impaired as a consequence of the different groove dimensions and the presence of thymine methyl groups at the binding site. This results in an 8.6 kJmoF reduced free energy of binding for the PS dA·sequence. Replacement of the bulky methyl group with a hydrogen (ie. T -> U) results in significantly stronger Hoechst 33258 binding to the parallel dA·dU sequences with a penalty of only 4.1 kJmol?1. Our data demonstrate that although Hoechst 33258 detects the altered groove, it is still able to bind a PS duplex containing dA·dU base pairs with high affinity, despite the large structural differences from its regular binding site in APS DNA. 相似文献
157.
158.
It is well known that proprioception is composed of the senses of movement and position. Whereas tests of position sense are quite commonly used, tests of the acuity in perception of movement velocity are scarce. In the present study we examined some novel tests for assessing the sense of limb movement velocity, involving replication and discrimination of single-joint movement velocity. Specifically, we investigated: (1) whether replication of limb movement velocity is more accurate following active criterion movements as compared to passive; (2) whether antagonist muscle contraction during passive limb movement enhances velocity discrimination; (3) how criterion movement velocity influences response accuracy; (4) the relationship between movement velocity and movement extent during velocity replication; and (5) whether subjects really base discrimination of velocities on perceived velocity. Sixteen healthy subjects participated in four tests (I-IV). For each test, horizontal abductions were performed about the right glenohumeral joint from the sagittal plane. The subjects were required to actively replicate the velocity of either an active (Test I) or passive (Test II) criterion movement, or judge whether a passive/semipassive (passive during antagonist muscle contraction) movement was faster or slower than a previous passive/semipassive criterion movement (Test III/IV). The results revealed higher response accuracy for Test I compared to Test II and for slower movements compared to faster, but no difference in response accuracy between Test III and IV. For velocity discrimination, the analysis revealed that the subjects based their judgment on the difference between criterion and comparison velocity rather than time or extent cues. 相似文献
159.
María Victoria Albarracín Johan Six Benjamin Z. Houlton Caroline S. Bledsoe 《Oecologia》2013,173(4):1439-1450
Ectomycorrhizal (EM) fungi form relationships with higher plants; plants transfer C to fungi, and fungi transfer nutrients to their host. While evidence indicates that this interaction is largely mutualistic, less is known about how nutrient supply and EM associates may alter C and nutrient exchanges, especially in intact plant-soil-microbe systems in the field. In a dual-labeling experiment with N fertilization, we used C and N stable isotopes to examine in situ transfers in EM pine trees in a Pinus sabiniana woodland in northern California. We added 15NH4SO2 and 13CO2 to track 13C transfer from pine needles to EM roots and 15N transfer from soil to EM roots and pine needles. Transfers of 13C and 15N differed with EM morphotype and with N fertilization. The brown morphotype received the least C per unit of N transferred (5:1); in contrast red and gold morphotypes gained more C and transferred less N (17:1 and 25:1, respectively). N fertilization increased N retention by ectomycorrhizas (EMs) but did not increase N transfer from EMs to pine needles. Therefore N fertilization positively affected both nutrient and C gains by EMs, increasing net C flows and N retention in EMs. Our work on intact and native trees/EM associations thereby extends earlier conclusions based on pot studies with young plants and culturable EM fungi; our results support the concept that EM-host relationships depend on species-level differences as well as responses to soil resources such as N. 相似文献
160.
Ping‐Pin Zheng Marcel van der Weiden Peter J. van der Spek Arnaud J.P.E. Vincent Johan M. Kros 《Journal of cellular physiology》2013,228(7):1383-1390
Literature data indicate that glioma stem cells may give rise to both tumor cells and endothelial progenitor cells (EPCs). Malignant glioma patients usually have increased levels of circulating (EPCs) and these cells are known to contribute to the glioma neovasculature. In this study we compared the intratumoral and circulating EPCs of glioma patients for a set of common glioma genotypical aberrations (amplification of EGFR; deletion of PTEN and aneusomy of chromosomes 7 and 10). We found that the EPCs present in the tumor tissues, not the circulating EPCs, share genetic aberrations with the tumor cells. EPCs with EGFR amplification were found in 46% and with PTEN deletion in 36% of the cases. EPCs with polysomy 7 and monosomy 10 were detected in 56% and 38% of the cases while centrosomal abnormalities in EPCs were found in 68% of the cases. The presence of genetic aberrations of glioma cells in intratumoral EPCs may point to transdifferentiation of glioma stem cells into EPCs. However, the tissue specific CD133 splice variant of blood EPCs was detected in the glioma tissues but not in control brains, suggestive of a blood origin of at least part of the intratumoral EPCs. The findings highlight the complexity of the cellular constituents of glioma neovascularization which should be taken into account when developing anti‐angiogenic strategies for gliomas. J. Cell. Physiol. 228: 1383–1390, 2013. © 2012 Wiley Periodicals, Inc. 相似文献