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991.
992.
The consequences of the seed deposition of the parasitic mistletoe Psittacanthus schiedeanus were evaluated in a 32-mo study. We conducted a field seed inoculation experiment to determine variation in seed adhesion, seed germination, seedling establishment, and plant survival to reproduction among five host species and to evaluate whether these post-dispersal processes explain mistletoe prevalence and specificity at the regional scale. Seeds without an exocarp were inoculated onto branches of individuals of the five most common host species identified in nature in central Veracruz, México. Seed fate was monitored for 2 yr, at weekly intervals for the first 2 mo and at 2-mo intervals thereafter. The height and diameter of experimental host branches and canopy cover above them were measured to see if these factors affected mistletoe establishment. Significant differences in seed attachment and seed germination were found among host species. Fewer seeds remained attached on experimental branches of Quercus germana than those of Liquidambar styraciflua, Acacia pennatula, and Platanus mexicana. Although significant differences in seed germination were observed among species (significantly greater on A. pennatula), >70% of mistletoe seeds germinated within the first 5 wk on all host species. Towards the end of the inoculation experiment, more mistletoe seedlings survived, grew, and then flowered on Liquidambar styraciflua than on A. pennatula, P. mexicana, Q. germana, or Q. leiophylla. Host branch initial height and diameter did not affect seedling survival, but seedlings survived better on trees where the canopy was more open. Our results suggest that Liquidambar styraciflua is the most compatible host species with P. schiedeanus in central Veracruz. Not surprisingly, Liquidambar is by far the most common host tree for P. schiedeanus in this area as well. We suggest that the observed local specialization is a result of seed dispersal as consequence of bird foraging and territorial behavior, host abundance, and host species compatibility. 相似文献
993.
Nayeli Goreti Nieto-Velázquez Yessica Dorin Torres-Ramos José Luis Mu?oz-Sánchez Lorena Espinosa-Godoy Susana Gómez-Cortés José Moreno Mario Adán Moreno-Eutimio 《Translational oncology》2016,9(5):384-391
Human natural killer (NK) cells are considered professional cytotoxic cells that are integrated into the effector branch of innate immunity during antiviral and antitumoral responses. The purpose of this study was to examine the peripheral distribution and expression of NK cell activation receptors from the fresh peripheral blood mononuclear cells of 30 breast cancer patients prior to any form of treatment (including surgery, chemotherapy, and radiotherapy), 10 benign breast pathology patients, and 24 control individuals. CD3−CD56dimCD16bright NK cells (CD56dim NK) and CD3−CD56brightCD16dim/− NK cells (CD56bright NK) were identified using flow cytometry. The circulating counts of CD56dim and CD56bright NK cells were not significantly different between the groups evaluated, nor were the counts of other leukocyte subsets between the breast cancer patients and benign breast pathology patients. However, in CD56dim NK cells, NKp44 expression was higher in breast cancer patients (P = .0302), whereas NKp30 (P = .0005), NKp46 (P = .0298), and NKG2D (P = .0005) expression was lower with respect to healthy donors. In CD56bright NK cells, NKp30 (P = .0007), NKp46 (P = .0012), and NKG2D (P = .0069) expression was lower in breast cancer patients compared with control group. Only NKG2D in CD56bright NK cells (P = .0208) and CD56dim NK cells (P = .0439) showed difference between benign breast pathology and breast cancer patients. Collectively, the current study showed phenotypic alterations in activation receptors on CD56dim and CD56bright NK cells, suggesting that breast cancer patients have decreased NK cell cytotoxicity. 相似文献
994.
Lorena Ribeiro de A. Carneiro Albertina P. Lima Ricardo B. Machado William E. Magnusson 《PloS one》2016,11(1)
Species-distribution models (SDM) are tools with potential to inform environmental-impact studies (EIA). However, they are not always appropriate and may result in improper and expensive mitigation and compensation if their limitations are not understood by decision makers. Here, we examine the use of SDM for frogs that were used in impact assessment using data obtained from the EIA of a hydroelectric project located in the Amazon Basin in Brazil. The results show that lack of knowledge of species distributions limits the appropriate use of SDM in the Amazon region for most target species. Because most of these targets are newly described and their distributions poorly known, data about their distributions are insufficient to be effectively used in SDM. Surveys that are mandatory for the EIA are often conducted only near the area under assessment, and so models must extrapolate well beyond the sampled area to inform decisions made at much larger spatial scales, such as defining areas to be used to offset the negative effects of the projects. Using distributions of better-known species in simulations, we show that geographical-extrapolations based on limited information of species ranges often lead to spurious results. We conclude that the use of SDM as evidence to support project-licensing decisions in the Amazon requires much greater area sampling for impact studies, or, alternatively, integrated and comparative survey strategies, to improve biodiversity sampling. When more detailed distribution information is unavailable, SDM will produce results that generate uncertain and untestable decisions regarding impact assessment. In many cases, SDM is unlikely to be better than the use of expert opinion. 相似文献
995.
Christian Silva-Platas Carlos Enrique Guerrero-Beltrán Mariana Carrancá Elena Cristina Castillo Judith Bernal-Ramírez Yuriana Oropeza-Almazán Lorena N. González Rocío Rojo Luis Enrique Martínez Juan Valiente-Banuet Lena Ruiz-Azuara María Elena Bravo-Gómez Noemí García Karla Carvajal Gerardo García-Rivas 《Journal of bioenergetics and biomembranes》2016,48(1):43-54
996.
Jesús Rodríguez-Bonilla Lorena Vargas-Rodríguez Carlos Calvo-Méndez Arturo Flores-Carreón Everardo López-Romero 《Antonie van Leeuwenhoek》1998,73(4):373-380
A mixed membrane fraction isolated from C. albicans yeast cells catalyzed the transfer of glucose from UDP-Glc into three classes of endogenous acceptors: glucolipid, glycoprotein and lipid-linked oligosaccharides. About 80 of the total radioactivity transferred into these products corresponded to the glucolipid which was identified as dolichol phosphate glucose by several criteria. The remainder was detected in about equal proportions in the other two fractions. Conditions that stimulated or inhibited glucolipid synthesis did not affect the extent of glycoprotein labeling. The synthesis of dolichol phosphate glucose exhibited a Kmof 104 M UDP-Glc and was stimulated by Mg2+but not by Mn2+or Ca2+. The latter cations were, however, better stimulators of glycoprotein labeling than Mg2+. Most nucleotides strongly inhibited the synthesis of dolichol phosphate glucose, UMP being a competitive inhibitor with a Kiof 100 M. The dolichol phosphate glucose synthase reaction was reversed about 57 by 0.62 mM UDP but not by UMP. 相似文献
997.
Characterization of cry Genes in a Mexican Bacillus thuringiensis Strain Collection 总被引:12,自引:0,他引:12
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Alejandra Bravo Sergio Sarabia Lorena Lopez Hernesto Ontiveros Carolina Abarca Anabel Ortiz Miriam Ortiz Laura Lina Francisco J. Villalobos Guadalupe Pea María-Eugenia Nuez-Valdez Mario Sobern Rodolfo Quintero 《Applied microbiology》1998,64(12):4965-4972
Mexico is located in a transition zone between the Nearctic and Neotropical biogeographical regions and contains a rich and unique biodiversity. A total of 496 Bacillus thuringiensis strains were isolated from 503 soil samples collected from the five macroregions of the country. The characterization of the strain collection provided useful information on the ecological patterns of distribution of B. thuringiensis and opportunities for the selection of strains to develop novel bioinsecticidal products. The analysis of the strains was based on multiplex PCR with novel general and specific primers that could detect the cry1, cry3, cry5, cry7, cry8, cry9, cry11, cry12, cry13, cry14, cry21, and cyt genes. The proteins belonging to the Cry1 and Cry9 groups are toxic for lepidopteran insects. The Cry3, Cry7, and Cry8 proteins are active against coleopteran insects. The Cry5, Cry12, Cry13, and Cry14 proteins are nematocidal. The Cry11, Cry21, and Cyt proteins are toxic for dipteran insects. Six pairs of general primers are used in this method. Strains for which unique PCR product profiles were obtained with the general primers were further characterized by additional PCRs with specific primers. Strains containing cry1 genes were the most abundant in our collection (49.5%). Thirty-three different cry1-type profiles were identified. B. thuringiensis strains harboring cry3 genes represented 21.5% of the strains, and 7.9% of the strains contained cry11 and cyt genes. cry7, cry8, and cry9 genes were found in 0.6, 2.4, and 2.6% of the strains, respectively. No strains carrying cry5, cry12, cry13, cry14, or cry21 genes were found. Finally, 14% of the strains did not give any PCR product and did not react with any polyclonal antisera. Our results indicate the presence of strains that may harbor potentially novel Cry proteins as well as strains with combinations of less frequently observed cry genes. 相似文献
998.
Julia Bechteler Gabriel Peñaloza-Bojacá David Bell J. Gordon Burleigh Stuart F. McDaniel E. Christine Davis Emily B. Sessa Alexander Bippus D. Christine Cargill Sahut Chantanoarrapint Isabel Draper Lorena Endara Laura L. Forrest Ricardo Garilleti Sean W. Graham Sanna Huttunen Javier Jauregui Lazo Francisco Lara Juan Larraín Lily R. Lewis David G. Long Dietmar Quandt Karen Renzaglia Alfons Schäfer-Verwimp Gaik Ee Lee Adriel M. Sierra Matt von Konrat Charles E. Zartman Marta Regina Pereira Bernard Goffinet Juan Carlos Villarreal A. 《American journal of botany》2023,110(11):e16249
Premise
Bryophytes form a major component of terrestrial plant biomass, structuring ecological communities in all biomes. Our understanding of the evolutionary history of hornworts, liverworts, and mosses has been significantly reshaped by inferences from molecular data, which have highlighted extensive homoplasy in various traits and repeated bursts of diversification. However, the timing of key events in the phylogeny, patterns, and processes of diversification across bryophytes remain unclear.Methods
Using the GoFlag probe set, we sequenced 405 exons representing 228 nuclear genes for 531 species from 52 of the 54 orders of bryophytes. We inferred the species phylogeny from gene tree analyses using concatenated and coalescence approaches, assessed gene conflict, and estimated the timing of divergences based on 29 fossil calibrations.Results
The phylogeny resolves many relationships across the bryophytes, enabling us to resurrect five liverwort orders and recognize three more and propose 10 new orders of mosses. Most orders originated in the Jurassic and diversified in the Cretaceous or later. The phylogenomic data also highlight topological conflict in parts of the tree, suggesting complex processes of diversification that cannot be adequately captured in a single gene-tree topology.Conclusions
We sampled hundreds of loci across a broad phylogenetic spectrum spanning at least 450 Ma of evolution; these data resolved many of the critical nodes of the diversification of bryophytes. The data also highlight the need to explore the mechanisms underlying the phylogenetic ambiguity at specific nodes. The phylogenomic data provide an expandable framework toward reconstructing a comprehensive phylogeny of this important group of plants. 相似文献999.
Marcos J. Espino Ureña Albert Katchborian-Neto Alexander Benítez Trinidad Maritza Ramírez Ramírez Manuel Vásquez Tineo José Vilemar de Araújo-Filho Wesley Lyeverton Correia Ribeiro Débora de Souza Collares Maia Castelo-Branco Lorena Mayana Beserra de Oliveira Claudia Maria Leal Bevilaqua Daniela Aparecida Chagas-Paula Claudio Viegas Jr. Marcos José Marques 《化学与生物多样性》2023,20(7):e202300135
Gastrointestinal nematode parasitism is a major burden to small ruminant production globally, compounded by increasing anthelmintic resistance. Previous studies have identified essential oils (EOs) from the Lippia genus with antiprotozoal and anthelmintic effects. Lippia dominguensis Moldenke (Ld), an endemic specie from the Dominican Republic, has similar popular uses, however, is chemically and pharmacologically yet uncharacterized. Here, we investigated the in vitro anthelmintic activity of LdEO and its ultrastructural effects on eggs and adult nematodes of Haemonchus contortus multidrug-resistant isolated. The GC/MS analysis showed linalool (33.85 %), 1,8-cineole (30.88 %), and δ-terpineol (10.61 %) as the main EO constituents. The LdEO showed an IC50=0.523 mg/mL in the egg hatch test, and the motility in the adult worm motility test was 95.8 % at 1 mg/mL. The confocal scanning laser microscopy of eggs indicated permeabilization or disruption of egg cell membranes as the possible mechanism of action of LdEO. The scanning electron microscopy of adult worms showed wrinkling, undulations, and cuticular disruptions. The LdEO displayed significant in vitro anthelmintic activity on eggs and adult worms of H. contortus. Additionally, the LdEO showed low oral toxicity in mice at 2,000 mg/kg. Thus, additional in vivo studies are justified to determine its anthelmintic efficacy in small ruminants. 相似文献
1000.
Edgar Zenteno Ricardo Lascurain Luis F. Montaño Lorena Vazquez Henri Debray Jean Montreuil 《Glycoconjugate journal》1992,9(4):204-208
We have demonstrated thatAmaranthus leucocarpus lectin hemagglutinating activity was powerfully inhibited by the T-antigen, containing Gal(1–3)GalNAc(1–3)Ser/Thr, and the Tn-antigen, which contains GalNAc(1–3)Ser/Thr. This suggests that the acetamido group at C-2 and the axial -OH at C-4 of theN-acetyl-D-galactopyranosylamine ring are important for lectin binding. The hemagglutination assays also established that desialylated and Pronase-treated human typeO erythrocytes with an M phenotype were better recognized than erythrocytes from all other blood groups. The recognition was dependent on pH and ionic strength. 相似文献