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281.
282.
Bacillus subtilis attachment to Aspergillus niger hyphae results in mutually altered metabolism
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283.
Gonzalo Machado-Schiaffino Andreas F Kautt Henrik Kusche Axel Meyer 《BMC evolutionary biology》2015,15(1)
Background
The enormous diversity found in East African cichlid fishes in terms of morphology, coloration, and behavior have made them a model for the study of speciation and adaptive evolution. In particular, haplochromine cichlids, by far the most species-rich lineage of cichlids, are a well-known textbook example for parallel evolution. Southwestern Uganda is an area of high tectonic activity, and is home to numerous crater lakes. Many Ugandan crater lakes were colonized, apparently independently, by a single lineage of haplochromine cichlids. Thereby, this system could be considered a natural experiment in which one can study the interaction between geographical isolation and natural selection promoting phenotypic diversification.Results
We sampled 13 crater lakes and six potentially-ancestral older lakes and, using both mitochondrial and microsatellite markers, discovered strong genetic and morphological differentiation whereby (a) geographically close lakes tend to be genetically more similar and (b) three different geographic areas seem to have been colonized by three independent waves of colonization from the same source population. Using a geometric morphometric approach, we found that body shape elongation (i.e. a limnetic morphology) evolved repeatedly from the ancestral deeper-bodied benthic morphology in the clear and deep crater lake habitats.Conclusions
A pattern of strong genetic and morphological differentiation was observed in the Ugandan crater lakes. Our data suggest that body shape changes have repeatedly evolved into a more limnetic-like form in several Ugandan crater lakes after independent waves of colonization from the same source population. The observed morphological changes in crater lake cichlids are likely to result from a common selective regime.Electronic supplementary material
The online version of this article (doi:10.1186/s12862-015-0287-3) contains supplementary material, which is available to authorized users. 相似文献284.
285.
286.
Jabari S da Silveira AB de Oliveira EC Neto SG Quint K Neuhuber W Brehmer A 《Histochemistry and cell biology》2011,135(1):47-57
One frequent chronic syndrome of Chagas’ disease is megacolon, an irreversible dilation of a colonic segment. Extensive enteric
neuron loss in the affected segment is regarded as key factor for deficient motility. Here, we assessed the quantitative balance
between cholinergic and nitrergic neurons representing the main limbs of excitatory and inhibitory colonic motor innervation,
respectively. From surgically removed megacolonic segments of four patients, each three myenteric wholemounts (from non-dilated
oral, megacolonic and non-dilated anal parts) was immunohistochemically triple-stained for choline acetyltransferase, neuronal
nitric oxide synthase (NOS) and the panneuronal human neuronal protein Hu C/D. Degenerative changes were most pronounced in
the megacolonic and anal regions, e.g. bulked, honeycomb-like ganglia with few neurons which were partly enlarged or atrophic
or vacuolated. Neuron counts from each 15 ganglia of 12 megacolonic wholemounts were compared with those of 12 age- and region-matched
controls. Extensive neuron loss, mainly in megacolonic and anal wholemounts, was obvious. In all three regions derived from
megacolonic samples, the proportion of NOS-positive neurons (control: 55%) was significantly increased: in non-dilated oral
parts to 61% (p = 0.003), in megacolonic regions to 72% (p < 0.001) and in non-dilated anal regions to 78% (p < 0.001). We suggest the chronic dilation of megacolonic specimens to be due to the preponderance of the nitrergic, inhibitory
input to the intestinal muscle. However, the observed neuronal imbalance was not restricted to the dilated regions: the non-dilated
anal parts may be innervated by ascending, cholinergic axons emerging from less affected, more anally located regions. 相似文献
287.
Captive breeding has become an important tool in species conservation programmes. Current management strategies for ex situ populations are based on theoretical models, which have mainly been tested in model species or assessed using studbook data.
During recent years an increasing number of molecular genetic studies have been published on captive populations of several
endangered species. However, a comprehensive analysis of these studies is still outstanding. Here, we present a review of
the published literature on ex situ conservation genetics with a focus on molecular studies. We analysed 188 publications which either presented empirical studies
using molecular markers (105), studbook analyses (26), theoretical work (38), or tested the genetic effects of management
strategies using model species (19). The results show that inbreeding can be minimized by a thorough management of captive
populations. There seems to be a minimum number of founders (15) and a minimum size of a captive population (100) necessary
in order to minimize a loss of genetic diversity. Optimally, the founders should be unrelated and new founders should be integrated
into the captive population successively. We recommend that genetic analyses should generally precede and accompany ex situ conservation projects in order to avoid inbreeding and outbreeding depression. Furthermore, many of the published studies
do not provide all the relevant parameters (founder size, captive population size, Ho, He, inbreeding coefficients). We, therefore, propose that a general standard for the presentation of genetic studies should
be established, which would allow integration of the data into a global database. 相似文献
288.
In the piriform cortex, individual odorants activate a unique ensemble of neurons that are distributed without discernable spatial order. Piriform neurons receive convergent excitatory inputs from random collections of olfactory bulb glomeruli. Pyramidal cells also make extensive recurrent connections with other excitatory and inhibitory neurons. We introduced channelrhodopsin into the piriform cortex to characterize these intrinsic circuits and to examine their contribution to activity driven by afferent bulbar inputs. We demonstrated that individual pyramidal cells are sparsely interconnected by thousands of excitatory synaptic connections that extend, largely undiminished, across the piriform cortex, forming a large excitatory network that can dominate the bulbar input. Pyramidal cells also activate inhibitory interneurons that mediate strong, local feedback inhibition that scales with excitation. This recurrent network can enhance or suppress bulbar input, depending on whether the input arrives before or after the cortex is activated. This circuitry may shape the ensembles of piriform cells that encode odorant identity. 相似文献
289.
Pituitary tumors are common intracranial neoplasms, yet few germline abnormalities have been implicated in their pathogenesis. Here we show that a single nucleotide germline polymorphism (SNP) substituting an arginine (R) for glycine (G) in the FGFR4 transmembrane domain can alter pituitary cell growth and hormone production. Compared with FGFR4-G388 mammosomatotroph cells that support prolactin (PRL) production, FGFR4-R388 cells express predominantly growth hormone (GH). Growth promoting effects of FGFR4-R388 as evidenced by enhanced colony formation was ascribed to Src activation and mitochondrial serine phosphorylation of STAT3 (pS-STAT3). In contrast, diminished pY-STAT3 mediated by FGFR4-R388 relieved GH inhibition leading to hormone excess. Using a knock-in mouse model, we demonstrate the ability of FGFR4-R385 to promote GH pituitary tumorigenesis. In patients with acromegaly, pituitary tumor size correlated with hormone excess in the presence of the FGFR4-R388 but not the FGFR4-G388 allele. Our findings establish a new role for the FGFR4-G388R polymorphism in pituitary oncogenesis, providing a rationale for targeting Src and STAT3 in the personalized treatment of associated disorders. 相似文献
290.
Moritz Muschick Marta Barluenga Walter Salzburger Axel Meyer 《BMC evolutionary biology》2011,11(1):116