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991.
There is a general lack of genomic information available for chlorophyte seaweed genera such as Ulva, and in particular there is no information concerning the genes that contribute to adhesion and cell wall biosynthesis for this organism. Partial sequencing of cDNA libraries to generate expressed sequence tags (ESTs) is an effective means of gene discovery and characterization of expression patterns. In this study, a cDNA library was created from sporulating tissue of Ulva linza L. Initially, 650 ESTs were randomly selected from a cDNA library and sequenced from their 5′ ends to obtain an indication of the level of redundancy of the library (21%). The library was normalized to enrich for rarer sequences, and a further 1920 ESTs were sequenced. These sequences were subjected to contig assembly that resulted in a unigene set of approximately 1104 ESTs. Forty‐eight percent of these sequences exhibited significant similarity to sequences in the databases. Phylogenetic comparisons are made between selected sequences with similarity in the databases to proteins involved in aspects of extracellular matrix/cell wall assembly and adhesion. 相似文献
992.
Johnson JC Nettikadan SR Vengasandra SG Lovan S Muys J Henderson E Christiansen J 《In vitro cellular & developmental biology. Animal》2005,41(7):225-231
Summary Melanomacrophages (MMs) are a component of an internal, pigmented cell system in liver and splenic tissues of some fishes,
anurans, and reptiles. The cells have been found in centers or aggregates in sinusoids and are associated with cells capable
of producing a peptide cytokine and immunoglobulins. A unique cell extension process has been observed in turtle MMs placed
into cell culture, and this process has been studied by light and atomic force microscopy. These structures, referred to as
cablepodia, are uniquely straight, narrow, and unbranching and appear to originate from growth cones opposite lamellipodia.
Cablepodia were found to connect with other turtle MMs and fibroblasts forming cell networks. Dividing fibroblasts to which
a cablepodium attached ceased cell division. The observations collectively suggest that a principal reason for aggregations
of MMs in internal organs of lower vertebrates in their ability to form interconnected networks of cell processes for trapping
and processing of particulate matter, cells and infectious organisms and, possibly, for the communication of cell signals
and transfer of intracellular materials. 相似文献
993.
994.
Frelichowski JE Palmer MB Main D Tomkins JP Cantrell RG Stelly DM Yu J Kohel RJ Ulloa M 《Molecular genetics and genomics : MGG》2006,275(5):479-491
Fine mapping and positional cloning will eventually improve with the anchoring of additional markers derived from genomic
clones such as BACs. From 2,603 new BAC-end genomic sequences from Gossypium hirsutum Acala ‘Maxxa’, 1,316 PCR primer pairs (designated as MUSB) were designed to flank microsatellite or simple sequence repeat
motif sequences. Most (1164 or 88%) MUSB primer pairs successfully amplified DNA from three species of cotton with an average
of three amplicons per marker and 365 markers (21%) were polymorphic between G.
hirsutum and G. barbadense. An interspecific RIL population developed from the above two entries was used to map 433 marker loci and 46 linkage groups
with a genetic distance of 2,126.3 cM covering approximately 45% of the cotton genome and an average distance between two
loci of 4.9 cM. Based on genome-specific chromosomes identified in G. hirsutum tetraploid (A and D), 56.9% of the coverage was located on the A subgenome while 39.7% was assigned to the D subgenome in
the genetic map, suggesting that the A subgenome may be more polymorphic and recombinationally active than originally thought.
The linkage groups were assigned to 23 of the 26 chromosomes. This is the first genetic map in which the linkage groups A01
and A02/D03 have been assigned to specific chromosomes. In addition the MUSB-derived markers from BAC-end sequences markers
allows fine genetic and QTL mapping of important traits and for the first time provides reconciliation of the genetic and
physical maps. Limited QTL analyses suggested that loci on chromosomes 2, 3, 12, 15 and 18 may affect variation in fiber quality
traits. The original BAC clones containing the newly mapped MUSB that tag the QTLs provide critical DNA regions for the discovery
of gene sequences involved in biological processes such as fiber development and pest resistance in cotton.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. 相似文献
995.
Maria J. Sanchez James M. Bradeen 《Molecular breeding : new strategies in plant improvement》2006,17(2):137-148
Resistance (R) genes and the proteins they encode are key components of the defense system of plants. The exploration of R
gene diversity enables the study of R gene evolution and may facilitate the isolation of new and functional alleles. Most
cloned R genes occur in clusters of related sequences. Thus, the development of a tool for reliable recovery of orthologous
R gene sequences to the exclusion of paralogous sequences will facilitate R gene diversity analysis. The late blight resistance
gene RB is a single functional locus embedded within a cluster of related sequences. Previously, the functional RB allele was cloned from wild potato using a Long Range-PCR (LR-PCR) technique, suggesting this method may be a promising tool
for recovery of R gene orthologs in other genotypes. Using the RB gene as a model, we explored the limitations and improved three technical aspects of LR-PCR for multi-genotype applications.
We present improved primers for the recovery of the RB locus and have identified efficient DNA extraction procedures and reliable amplification systems. We document that consensus
sequences built from three independently generated LR-PCR clones can be up to 100% accurate. Our results show encouraging
advances toward successful application of LR-PCR for isolating alleles from orthologous R gene loci. 相似文献
996.
997.
Terner J Palaniappan V Gold A Weiss R Fitzgerald MM Sullivan AM Hosten CM 《Journal of inorganic biochemistry》2006,100(4):480-501
The catalytic cycle intermediates of heme peroxidases, known as compounds I and II, have been of long standing interest as models for intermediates of heme proteins, such as the terminal oxidases and cytochrome P450 enzymes, and for non-heme iron enzymes as well. Reports of resonance Raman signals for compound I intermediates of the oxo-iron(IV) porphyrin pi-cation radical type have been sometimes contradictory due to complications arising from photolability, causing compound I signals to appear similar to those of compound II or other forms. However, studies of synthetic systems indicated that protein based compound I intermediates of the oxoiron(IV) porphyrin pi-cation radical type should exhibit vibrational signatures that are different from the non-radical forms. The compound I intermediates of horseradish peroxidase (HRP), and chloroperoxidase (CPO) from Caldariomyces fumago do in fact exhibit unique and characteristic vibrational spectra. The nature of the putative oxoiron(IV) bond in peroxidase intermediates has been under discussion in the recent literature, with suggestions that the Fe(IV)O unit might be better described as Fe(IV)-OH. The generally low Fe(IV)O stretching frequencies observed for proteins have been difficult to mimic in synthetic ferryl porphyrins via electron donation from trans axial ligands alone. Resonance Raman studies of iron-oxygen vibrations within protein species that are sensitive to pH, deuteration, and solvent oxygen exchange, indicate that hydrogen bonding to the oxoiron(IV) group within the protein environment contributes to substantial lowering of Fe(IV)O frequencies relative to those of synthetic model compounds. 相似文献
998.
Zeidan YH Pettus BJ Elojeimy S Taha T Obeid LM Kawamori T Norris JS Hannun YA 《The Journal of biological chemistry》2006,281(34):24695-24703
Sphingolipids are well established effectors of signal transduction downstream of the tumor necrosis factor (TNF) receptor. In a previous study, we showed that the sphingosine kinase/sphingosine 1-phosphate (S1P) pathway couples TNF receptor to induction of the cyclooxygenase 2 gene and prostaglandin synthesis (Pettus, B. J., Bielawski, J., Porcelli, A. M., Reames, D. L., Johnson, K. R., Morrow, J., Chalfant, C. E., Obeid, L. M., and Hannun, Y. A. (2003) FASEB J. 17, 1411-1421). In this study, the requirement for acid sphingomyelinase and sphingomyelin metabolites in the TNFalpha/prostaglandin E(2) (PGE(2)) pathway was investigated. The amphiphilic compound desipramine, a frequently employed inhibitor of acid sphingomyelinase (ASMase), blocked PGE(2) production. However, the action of desipramine was independent of its action on ASMase, since neither genetic loss of ASMase (Niemann-Pick fibroblasts) nor knockdown of ASMase using RNA interference affected TNFalpha-induced PGE(2) synthesis. Further investigations revealed that desipramine down-regulated acid ceramidase (AC), but not sphingosine kinase, at the protein level. This resulted in a time-dependent drop in sphingosine and S1P levels. Moreover, exogenous administration of either sphingosine or S1P rescued PGE(2) biosynthesis after desipramine treatment. Interestingly, knockdown of endogenous AC by RNA interference attenuated cyclooxygenase 2 induction by TNFalpha and subsequent PGE(2) biosynthesis. Taken together, these results define a novel role for AC in the TNFalpha/PGE(2) pathway. In addition, the results of this study warrant careful reconsideration of desipramine as a specific inhibitor for ASMase. 相似文献
999.
1000.
Ralph Mac Nally rew F. Bennett James R. Thomson James Q. Radford † Guy Unmack Gregory Horrocks Peter A. Vesk 《Diversity & distributions》2009,15(4):720-730
Aim We characterized changes in reporting rates and abundances of bird species over a period of severe rainfall deficiency and increasing average temperatures. We also measured flowering in eucalypts, which support large numbers of nectarivores characteristic of the region.
Location A 30,000-km2 region of northern Victoria, Australia, consisting of limited amounts of remnant native woodlands embedded in largely agricultural landscapes.
Methods There were three sets of monitoring studies, pitched at regional (survey programmes in 1995–97, 2004–05 and 2006–08), landscape (2002–03 and 2006–07) and site (1997–2008 continuously) scales. Bird survey techniques used a standard 2-ha, 20-min count method. We used Bayesian analyses of reporting rates to document statistically changes in the avifauna through time at each spatial scale.
Results Bird populations in the largest remnants of native vegetation (up to 40,000 ha), some of which have been declared as national parks in the past decade, experienced similar declines to those in heavily cleared landscapes. All categories of birds (guilds based on foraging substrate, diet, nest site; relative mobility; geographical distributions) were affected similarly. We detected virtually no bird breeding in the latest survey periods. Eucalypt flowering has declined significantly over the past 12 years of drought.
Main conclusions Declines in the largest woodland remnants commensurate with those in cleared landscapes suggest that reserve systems may not be relied upon to sustain species under climate change. We attribute population declines to low breeding success due to reduced food. Resilience of bird populations in this woodland system might be increased by active management to enhance habitat quality in existing vegetation and restoration of woodland in the more fertile parts of landscapes. 相似文献
Location A 30,000-km
Methods There were three sets of monitoring studies, pitched at regional (survey programmes in 1995–97, 2004–05 and 2006–08), landscape (2002–03 and 2006–07) and site (1997–2008 continuously) scales. Bird survey techniques used a standard 2-ha, 20-min count method. We used Bayesian analyses of reporting rates to document statistically changes in the avifauna through time at each spatial scale.
Results Bird populations in the largest remnants of native vegetation (up to 40,000 ha), some of which have been declared as national parks in the past decade, experienced similar declines to those in heavily cleared landscapes. All categories of birds (guilds based on foraging substrate, diet, nest site; relative mobility; geographical distributions) were affected similarly. We detected virtually no bird breeding in the latest survey periods. Eucalypt flowering has declined significantly over the past 12 years of drought.
Main conclusions Declines in the largest woodland remnants commensurate with those in cleared landscapes suggest that reserve systems may not be relied upon to sustain species under climate change. We attribute population declines to low breeding success due to reduced food. Resilience of bird populations in this woodland system might be increased by active management to enhance habitat quality in existing vegetation and restoration of woodland in the more fertile parts of landscapes. 相似文献