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81.
Anderson K Sizovs A Cortez M Waldron C Haddleton DM Reineke TM 《Biomacromolecules》2012,13(8):2229-2239
In this study, we have synthesized six analogs of a trehalose-pentaethylenehexamine glycopolymer (Tr4) that contain (1A) adamantane, (1B) carboxy, (1C) alkynyl-oligoethyleneamine, (1D) azido trehalose, (1E) octyl, or (1F) oligoethyleneamine end groups and evaluated the effects of polymer end group chemistry on the ability of these systems to bind, compact, and deliver pDNA to cultured HeLa cells. The polymers were synthesized in one-pot azide-alkyne cycloaddition reactions with an adaptation of the Carothers equation for step-growth polymerization to produce a series of polymers with similar degrees of polymerization. An excess of end-capping monomer was added at the end of the polymerizations to maximize functionalization efficiency, which was evaluated with GPC, NMR, and MALDI-TOF. The polymers were all found to bind and compact pDNA at similarly low N/P ratios and form polyplexes with plasmid DNA. The effects of the different end group structures were most evident in the polyplex internalization and transfection assays in the presence of serum as determined by flow cytometry and luciferase gene expression, respectively. The Tr4 polymers end-capped with carboxyl groups (1B) (N/P = 7), octyne (1E) (N/P = 7), and oligoethyleneamine (1F) (N/P = 7), were taken into cells as polyplex and exhibited the highest levels of fluorescence, resulting from labeled plasmid. Similarly, the polymers end-functionalized with carboxyl groups (1E at N/P = 7), octyl groups (1E at N/P = 15), and in particular oligoethyleneamine groups (1F at N/P = 15) yielded dramatically higher reporter gene expression in the presence of serum. This study yields insight into how very subtle structural changes in polymer chemistry, such as end groups can yield very significant differences in the biological delivery efficiency and transgene expression of polymers used for pDNA delivery. 相似文献
82.
Caruso JF Daily JS Mason ML Shepherd CM McLagan JR Marshall MR Walker RH West JO 《Journal of strength and conditioning research / National Strength & Conditioning Association》2012,26(1):284-292
The current study purpose examined the vertical height-anthropometry relationship with jump data obtained from an instrumented platform. Our methods required college-aged (n = 177) subjects to make 3 visits to our laboratory to measure the following anthropometric variables: height, body mass, upper arm length (UAL), lower arm length, upper leg length, and lower leg length. Per jump, maximum height was measured in 3 ways: from the subjects' takeoff, hang times, and as they landed on the platform. Standard multivariate regression assessed how well anthropometry predicted the criterion variance per gender (men, women, pooled) and jump height method (takeoff, hang time, landing) combination. Z-scores indicated that small amounts of the total data were outliers. The results showed that the majority of outliers were from jump heights calculated as women landed on the platform. With the genders pooled, anthropometry predicted a significant (p < 0.05) amount of variance from jump heights calculated from both takeoff and hang time. The anthropometry-vertical jump relationship was not significant from heights calculated as subjects landed on the platform, likely due to the female outliers. Yet anthropometric data of men did predict a significant amount of variance from heights calculated when they landed on the platform; univariate correlations of men's data revealed that UAL was the best predictor. It was concluded that the large sample of men's data led to greater data heterogeneity and a higher univariate correlation. Because of our sample size and data heterogeneity, practical applications suggest that coaches may find our results best predict performance for a variety of college-aged athletes and vertical jump enthusiasts. 相似文献
83.
Salter MD Nienhaus K Nienhaus GU Dewilde S Moens L Pesce A Nardini M Bolognesi M Olson JS 《The Journal of biological chemistry》2008,283(51):35689-35702
The major pathway for O2 binding to mammalian myoglobins (Mb) and hemoglobins (Hb) involves transient upward movement of the distal histidine (His-64(E7)), allowing ligand capture in the distal pocket. The mini-globin from Cerebratulus lacteus (CerHb) appears to have an alternative pathway between the E and H helices that is made accessible by loss of the N-terminal A helix. To test this pathway, we examined the effects of changing the size of the E7 gate and closing the end of the apolar channel in CerHb by site-directed mutagenesis. Increasing the size of Gln-44(E7) from Ala to Trp causes variation of association (k'O2) and dissociation (kO2) rate coefficients, but the changes are not systematic. More significantly, the fractions (Fgem approximately 0.05-0.19) and rates (kgem approximately 50-100 micros(-1)) of geminate CO recombination in the Gln-44(E7) mutants are all similar. In contrast, blocking the entrance to the apolar channel by increasing the size of Ala-55(E18) to Phe and Trp causes the following: 1) both k'O2 and kO2 to decrease roughly 4-fold; 2) Fgem for CO to increase from approximately 0.05 to 0.45; and 3) kgem to decrease from approximately 80 to approximately 9 micros(-1), as ligands become trapped in the channel. Crystal structures and low temperature Fourier-transform infrared spectra of Phe-55 and Trp-55 CerHb confirm that the aromatic side chains block the channel entrance, with little effect on the distal pocket. These results provide unambiguous experimental proof that diatomic ligands can enter and exit a globin through an interior channel in preference to the more direct E7 pathway. 相似文献
84.
The majority of species in the scincid genus Emoia (Squamata: Scincidae) have a fixed clutch size of two eggs per clutch and produce between two and four clutches per year. One lineage within Emoia, the Emoia samoensis species group, consists of 13 species occurring in Melanesia and the islands of the southwestern Pacific Ocean, and exhibits variation in clutch size, with previously reported clutch sizes of two to five eggs. Little is known about reproduction in several members of this lineage including Emoia sanfordi, a large-bodied lizard endemic to the archipelago of Vanuatu in the South Pacific. We analyzed reproduction and clutch size in E. sanfordi females and discovered that there is a substantial amount of intraspecific variation, with clutch size ranging from two to seven eggs, with a modal clutch size of five eggs. Females were reproductively active throughout the study period of June through October and appear to be laying multiple clutches. The variation in clutch size seen in E. sanfordi is congruent with the variation previously reported within other closely related species. 相似文献
85.
86.
Population structure of Purple Sandpipers (Calidris maritima) as revealed by mitochondrial DNA and microsatellites 下载免费PDF全文
Nathalie M. LeBlanc Donald T. Stewart Snaebjörn Pálsson Mark F. Elderkin Glen Mittelhauser Stephen Mockford Julie Paquet Gregory J. Robertson Ron W. Summers Lindsay Tudor Mark L. Mallory 《Ecology and evolution》2017,7(9):3225-3242
The Purple Sandpiper (Calidris maritima) is a medium‐sized shorebird that breeds in the Arctic and winters along northern Atlantic coastlines. Migration routes and affiliations between breeding grounds and wintering grounds are incompletely understood. Some populations appear to be declining, and future management policies for this species will benefit from understanding their migration patterns. This study used two mitochondrial DNA markers and 10 microsatellite loci to analyze current population structure and historical demographic trends. Samples were obtained from breeding locations in Nunavut (Canada), Iceland, and Svalbard (Norway) and from wintering locations along the coast of Maine (USA), Nova Scotia, New Brunswick, and Newfoundland (Canada), and Scotland (UK). Mitochondrial haplotypes displayed low genetic diversity, and a shallow phylogeny indicating recent divergence. With the exception of the two Canadian breeding populations from Nunavut, there was significant genetic differentiation among samples from all breeding locations; however, none of the breeding populations was a monophyletic group. We also found differentiation between both Iceland and Svalbard breeding populations and North American wintering populations. This pattern of divergence is consistent with a previously proposed migratory pathway between Canadian breeding locations and wintering grounds in the United Kingdom, but argues against migration between breeding grounds in Iceland and Svalbard and wintering grounds in North America. Breeding birds from Svalbard also showed a genetic signature intermediate between Canadian breeders and Icelandic breeders. Our results extend current knowledge of Purple Sandpiper population genetic structure and present new information regarding migration routes to wintering grounds in North America. 相似文献
87.
RAD sequencing reveals genomewide divergence between independent invasions of the European green crab (Carcinus maenas) in the Northwest Atlantic 下载免费PDF全文
Nicholas W. Jeffery Claudio DiBacco Mallory Van Wyngaarden Lorraine C. Hamilton Ryan R. E. Stanley Renée Bernier Jennifer FitzGerald K. Matheson C. H. McKenzie Praveen Nadukkalam Ravindran Robert Beiko Ian R. Bradbury 《Ecology and evolution》2017,7(8):2513-2524
Genomic studies of invasive species can reveal both invasive pathways and functional differences underpinning patterns of colonization success. The European green crab (Carcinus maenas) was initially introduced to eastern North America nearly 200 years ago where it expanded northwards to eastern Nova Scotia. A subsequent invasion to Nova Scotia from a northern European source allowed further range expansion, providing a unique opportunity to study the invasion genomics of a species with multiple invasions. Here, we use restriction‐site‐associated DNA sequencing‐derived SNPs to explore fine‐scale genomewide differentiation between these two invasions. We identified 9137 loci from green crab sampled from 11 locations along eastern North America and compared spatial variation to mitochondrial COI sequence variation used previously to characterize these invasions. Overall spatial divergence among invasions was high (pairwise FST ~0.001 to 0.15) and spread across many loci, with a mean FST ~0.052 and 52% of loci examined characterized by FST values >0.05. The majority of the most divergent loci (i.e., outliers, ~1.2%) displayed latitudinal clines in allele frequency highlighting extensive genomic divergence among the invasions. Discriminant analysis of principal components (both neutral and outlier loci) clearly resolved the two invasions spatially and was highly correlated with mitochondrial divergence. Our results reveal extensive cryptic intraspecific genomic diversity associated with differing patterns of colonization success and demonstrates clear utility for genomic approaches to delineating the distribution and colonization success of aquatic invasive species. 相似文献
88.
beta-Synuclein inhibits alpha-synuclein aggregation: a possible role as an anti-parkinsonian factor. 总被引:8,自引:0,他引:8
We characterized beta-synuclein, the non-amyloidogenic homolog of alpha-synuclein, as an inhibitor of aggregation of alpha-synuclein, a molecule implicated in Parkinson's disease. For this, doubly transgenic mice expressing human (h) alpha- and beta-synuclein were generated. In doubly transgenic mice, beta-synuclein ameliorated motor deficits, neurodegenerative alterations, and neuronal alpha-synuclein accumulation seen in halpha-synuclein transgenic mice. Similarly, cell lines transfected with beta-synuclein were resistant to alpha-synuclein accumulation. halpha-synuclein was coimmunoprecipitated with hbeta-synuclein in the brains of doubly transgenic mice and in the double-transfected cell lines. Our results raise the possibility that beta-synuclein might be a natural negative regulator of alpha-synuclein aggregation and that a similar class of endogenous factors might regulate the aggregation state of other molecules involved in neurodegeneration. Such an anti-amyloidogenic property of beta-synuclein might also provide a novel strategy for the treatment of neurodegenerative disorders. 相似文献
89.
Understanding predator-prey dynamics is an important component of management strategy development for wildlife populations that are directly affected by predation. Ungulates often serve as a significant source of prey for many large mammal predators, and patterns of predation are known to influence population dynamics. Although black bear and wolf diets have been investigated extensively, prey preference has been less commonly examined, especially in analyses that take into account age class (i.e., juvenile and adult) of the ungulate prey. We examined black bear (Ursus americanus), wolf (Canis lupus), and hybrids (Canis spp.) prey preference in Ontario based on the availability of three ungulate species—elk (Cervus elaphus), moose (Alces alces), and white-tailed deer (Odocoileus virginianus). We analyzed the presence of prey items in black bear and wolf scats collected over 3 years by examining prey hair cuticular scale patterns. We applied correction factors to frequencies of occurrence of prey items found in predator scat and related diet composition to the availability of ungulates, determined by fecal pellet transect surveys. In addition, non-ungulate diet items were identified to obtain full diet composition profiles. We found that black bear diet consisted of more than 87% vegetation, and they were opportunistic, not selecting for any particular ungulate species in either adult or juvenile age class. Wolf diet was comprised mainly of ungulates (~?73.2%), muskrat (Ondatra zibethica; ~?8.5%), and beaver (Castor canadensis; ~?14.6%), and although moose were at least 1.5 times more abundant then each of the other ungulate prey species in the study area, wolves preferred elk, using moose less than expected. Although we found black bear diet to be opportunistic during the summer, wolves in our study heavily utilized both juvenile and adult ungulates, however, among ungulate species, displayed preference for elk. The preference displayed by wolves provides insight that wildlife managers can use to guide further investigation and assist with the development of strategies to ensure continued elk reintroduction success, and moose and white-tailed deer population sustainability. 相似文献
90.
Presence or absence of fish as a cue to macroinvertebrate abundance in boreal wetlands 总被引:2,自引:2,他引:2
Mallory Mark L. Blancher Peter J. Weatherhead Patrick J. McNicol Donald K. 《Hydrobiologia》1994,(1):345-351
Waterfowl that eat macroinvertebrates must select among potential nesting or brood-rearing habitats that may vary in food abundance over the season. We compared the reliability of predicting the relative abundance of macroinvertebrates in boreal wetlands using either the number of macroinvertebrates collected at one sampling period, or presence or absence of fish. Wetlands with fish had fewer macroinvertebrates than fishless wetlands in all five sampling periods. Predictions of the relative abundance of invertebrates in a wetland at other sampling periods based on the presence or absence of fish, were equal to or better than predictions based on the actual number of macroinvertebrates collected during one sampling period. These results suggest that fish status of a wetland is a reliable cue to invertebrate abundance in boreal wetlands. 相似文献