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63.
Phylogeny of Impatiens (Balsaminaceae): integrating molecular and morphological evidence into a new classification 下载免费PDF全文
Sheng‐Xiang Yu Steven B. Janssens Xiang‐Yun Zhu Magnus Lidén Tian‐Gang Gao Wei Wang 《Cladistics : the international journal of the Willi Hennig Society》2016,32(2):179-197
Impatiens L. is one of the largest angiosperm genera, containing over 1000 species, and is notorious for its taxonomic difficulty. Here, we present, to our knowledge, the most comprehensive phylogenetic analysis of the genus to date based on a total evidence approach. Forty‐six morphological characters, mainly obtained from our own investigations, are combined with sequence data from three genetic regions, including nuclear ribosomal ITS and plastid atpB‐rbcL and trnL‐F. We include 150 Impatiens species representing all clades recovered by previous phylogenetic analyses as well as three outgroups. Maximum‐parsimony and Bayesian inference methods were used to infer phylogenetic relationships. Our analyses concur with previous studies, but in most cases provide stronger support. Impatiens splits into two major clades. For the first time, we report that species with three‐colpate pollen and four carpels form a monophyletic group (clade I). Within clade II, seven well‐supported subclades are recognized. Within this phylogenetic framework, character evolution is reconstructed, and diagnostic morphological characters for different clades and subclades are identified and discussed. Based on both morphological and molecular evidence, a new classification outline is presented, in which Impatiens is divided into two subgenera, subgen. Clavicarpa and subgen. Impatiens; the latter is further subdivided into seven sections. 相似文献
64.
Magnus Simonsson Mélanie Court Johan Bergholm Damien Lemarchand Stephen Hillier 《Biogeochemistry》2016,129(1-2):77-91
Clay minerals and K feldspars were evaluated as sources of K in a Norway spruce stand (Picea abies (L.) Karst.) from the Skogaby experimental forest in southwest Sweden. The soil, developed in a Quaternary glacial till, has only 3–5% clay, and more than 95% of its K resides in feldspars. Ratios of K/Rb were assessed in interlayers of 2:1 clay minerals (extracted with hot (100 °C) 2 M HCl), biomass and the forest floor. These compartments had similarly low K/Rb ratios, whereas K feldspars were significantly poorer in Rb. A fractionation model indicated preferential retention of Rb in the biomass and forest floor, due to stronger adsorption of Rb than K in the humus, as well as preferential uptake of K from the exchange complex in the mineral soil. Preferential uptake of K may result from weaker adsorption of K by the cation exchanger, or preference for dissolved K over Rb by the roots. A quantitative mineralogical analysis revealed that loss from micas may account for half of the Holocene loss of K from the soil, which was approximately 22 Mg ha?1. Exceptionally low K/Rb ratios in HCl extracts of the upper 60 cm of the profile indicated extensive loss of K from mica in the parent material and re-fixation of K and Rb at lower ratios. The results indicate that fixation in and release from clay minerals may be prominent in the cycling of K, even in a soil that is poor in clay minerals. 相似文献
65.
Ectopic position of duplicated KIT gene in African Nguni cattle,associated with color sidedness,confirms its shared ancestry with the Bos taurus lineage 下载免费PDF全文
66.
Niels M. Schmidt Rolf A. Ims Toke T. H?ye Olivier Gilg Lars H. Hansen Jannik Hansen Magnus Lund Eva Fuglei Mads C. Forchhammer Benoit Sittler 《Proceedings. Biological sciences / The Royal Society》2012,279(1746):4417-4422
Alpine and arctic lemming populations appear to be highly sensitive to climate change, and when faced with warmer and shorter winters, their well-known high-amplitude population cycles may collapse. Being keystone species in tundra ecosystems, changed lemming dynamics may convey significant knock-on effects on trophically linked species. Here, we analyse long-term (1988–2010), community-wide monitoring data from two sites in high-arctic Greenland and document how a collapse in collared lemming cyclicity affects the population dynamics of the predator guild. Dramatic changes were observed in two highly specialized lemming predators: snowy owl and stoat. Following the lemming cycle collapse, snowy owl fledgling production declined by 98 per cent, and there was indication of a severe population decline of stoats at one site. The less specialized long-tailed skua and the generalist arctic fox were more loosely coupled to the lemming dynamics. Still, the lemming collapse had noticeable effects on their reproductive performance. Predator responses differed somewhat between sites in all species and could arise from site-specific differences in lemming dynamics, intra-guild interactions or subsidies from other resources. Nevertheless, population extinctions and community restructuring of this arctic endemic predator guild are likely if the lemming dynamics are maintained at the current non-cyclic, low-density state. 相似文献
67.
Anderlid BM Schoumans J Annerén G Tapia-Paez I Dumanski J Blennow E Nordenskjöld M 《Human genetics》2002,110(5):439-443
Both cytogenetically visible and cryptic deletions of the terminal region of chromosome 22q are associated with a clinical phenotype including mental retardation, delay in expressive speech development, hypotonia, normal to accelerated growth and minor facial dysmorphic features. The genes responsible for the development of the phenotype have not yet been identified, but a distal localization is probable, since the cytogenetically visible and the cryptic deletions show a similar pattern of symptoms. We report a 33-year-old woman with a submicroscopic 22q13 deletion, mild mental retardation, speech delay, autistic symptoms and mild facial dysmorphic features. The deletion was mapped by FISH using cosmid probes from terminal 22q13, and the size of the deletion was estimated to be 100 kb. Three genes are affected by the deletion in this patient. ACR and RABL2B are deleted and proSAP2 is disrupted. This observation, together with recently published data, supports the notion that proSAP2 is the most important contributor to the 22q13 deletion phenotype. 相似文献
68.
Dominika Staniec Miroslaw Ksiazek Ida B. Th?gersen Jan J. Enghild Aneta Sroka Danuta Bryzek Matthew Bogyo Magnus Abrahamson Jan Potempa 《The Journal of biological chemistry》2015,290(45):27248-27260
Porphyromonas gingivalis is a peptide-fermenting asaccharolytic periodontal pathogen. Its genome contains several genes encoding cysteine peptidases other than gingipains. One of these genes (PG1055) encodes a protein called Tpr (thiol protease) that has sequence similarity to cysteine peptidases of the papain and calpain families. In this study we biochemically characterize Tpr. We found that the 55-kDa Tpr inactive zymogen proteolytically processes itself into active forms of 48, 37, and 33 kDa via sequential truncations at the N terminus. These processed molecular forms of Tpr are associated with the bacterial outer membrane where they are likely responsible for the generation of metabolic peptides required for survival of the pathogen. Both autoprocessing and activity were dependent on calcium concentrations >1 mm, consistent with the protein''s activity within the intestinal and inflammatory milieus. Calcium also stabilized the Tpr structure and rendered the protein fully resistant to proteolytic degradation by gingipains. Together, our findings suggest that Tpr is an example of a bacterial calpain, a calcium-responsive peptidase that may generate substrates required for the peptide-fermenting metabolism of P. gingivalis. Aside from nutrient generation, Tpr may also be involved in evasion of host immune response through degradation of the antimicrobial peptide LL-37 and complement proteins C3, C4, and C5. Taken together, these results indicate that Tpr likely represents an important pathogenesis factor for P. gingivalis. 相似文献
69.
Icelandic lampreys (<Emphasis Type="Italic">Petromyzon marinus</Emphasis>): where do they come from?
Ana M. Pereira Benony Jonsson Magnus Johannsson Joana I. Robalo Vítor C. Almada 《Ichthyological Research》2012,59(1):83-85
The recent discovery of sea lamprey wounds on salmonids in Icelandic rivers prompted an investigation on the origin of sea
lampreys in Icelandic waters. Using a mitochondrial DNA fragment, the origin of the lampreys examined was assigned to the
European stock and not to the North American one. 相似文献
70.
Lori Newman Jane Rowley Stephen Vander Hoorn Nalinka Saman Wijesooriya Magnus Unemo Nicola Low Gretchen Stevens Sami Gottlieb James Kiarie Marleen Temmerman 《PloS one》2015,10(12)