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961.
Jessica D. Wiley Emilio F. Merino Priscilla M. Krai Kyle J. McLean Abhai K. Tripathi Joel Vega-Rodríguez Marcelo Jacobs-Lorena Michael Klemba Maria B. Cassera 《Eukaryotic cell》2015,14(2):128-139
The malaria parasite harbors a relict plastid called the apicoplast and its discovery opened a new avenue for drug discovery and development due to its unusual, nonmammalian metabolism. The apicoplast is essential during the asexual intraerythrocytic and hepatic stages of the parasite, and there is strong evidence supporting its essential metabolic role during the mosquito stages of the parasite. Supply of the isoprenoid building blocks isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) is the essential metabolic function of the apicoplast during the asexual intraerythrocytic stages. However, the metabolic role of the apicoplast during gametocyte development, the malaria stages transmitted to the mosquito, remains unknown. In this study, we showed that production of IPP for isoprenoid biosynthesis is the essential metabolic function of the apicoplast during gametocytogenesis, by obtaining normal gametocytes lacking the apicoplast when supplemented with IPP. When IPP supplementation was removed early in gametocytogenesis, developmental defects were observed, supporting the essential role of isoprenoids for normal gametocytogenesis. Furthermore, mosquitoes infected with gametocytes lacking the apicoplast developed fewer and smaller oocysts that failed to produce sporozoites. This finding further supports the essential role of the apicoplast in establishing a successful infection in the mosquito vector. Our study supports isoprenoid biosynthesis as a valid drug target for development of malaria transmission-blocking inhibitors. 相似文献
962.
First Molecular Characterization of Cryptosporidium spp. Infecting Buffalo Calves in Brazil
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![点击此处可从《The Journal of eukaryotic microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Monally C. C. Aquino Giovanni Widmer Anaiza S. Zucatto Milena A. Viol Sandra V. Inácio Alex A. Nakamura Willian M. D. Coelho Silvia H. V. Perri Marcelo V. Meireles Katia D. S. Bresciani 《The Journal of eukaryotic microbiology》2015,62(5):657-661
With the aim of determining the occurrence of Cryptosporidium spp., 222 fecal samples were collected from Murrah buffalo calves aged up to 6 mo. Fecal DNA was genotyped with a nested polymerase chain reaction targeting the 18S rRNA gene and sequencing of the amplified fragment. Nested 18S PCR was positive for 48.2% of the samples. Sequence analysis showed that the most frequent species in these animals was Cryptosporidium ryanae, which was present in buffalo calves as young as 5 d. The zoonotic species Cryptosporidium parvum was detected in one animal. An uncommon Cryptosporidium 18S genotype was found in buffaloes. 相似文献
963.
Angiotensin II restricted analogs with biological activity in the erythrocytic cycle of Plasmodium falciparum
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![点击此处可从《Journal of peptide science》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Marcelo Der Torossian Torres Adriana Farias Silva Leandro de Souza Silva Ana Acácia de Sá Pinheiro Vani Xavier Jr. Oliveira 《Journal of peptide science》2015,21(1):24-28
The anti‐plasmodial activity of conformationally restricted analogs of angiotensin II against Plasmodium gallinaceum has been described. To observe activity against another Plasmodium species, invasion of red blood cells by Plasmodium falciparum was analyzed. Analogs restricted with lactam or disulfide bridges were synthesized to determine their effects and constraints in the peptide–parasite interaction. The analogs were synthesized using tert‐butoxycarbonyl and fluoromethoxycarbonyl solid phase methods, purified by liquid chromatography, and characterized by mass spectrometry. Results indicated that the lactam bridge restricted analogs 1 (Glu‐Asp‐Arg‐Orn ‐Val‐Tyr‐Ile‐His‐Pro‐Phe) and 3 (Asp‐Glu‐Arg‐Val‐Orn ‐Tyr‐Ile‐His‐Pro‐Phe) showed activity toward inhibition of ring formation stage of P. falciparum erythrocytic cycle, preventing invasion in about 40% of the erythrocytes. The disulfide‐bridged analog 10 (Cys‐Asp‐Arg‐Cys ‐Val‐Tyr‐Ile‐His‐Pro‐Phe) was less effective yet significant, showing a 25% decrease in infection of new erythrocytes. In all cases, the peptides presented no pressor activity, and hydrophobic interactions between the aromatic and alkyl amino acid side chains were preserved, a factor proven important in efficacy against P. gallinaceum. In contrast, hydrophilic interactions between the Asp1 carboxyl and Arg2 guanidyl groups proved not to be as important as they were in the case of P. gallinaceum, while interactions between the Arg2 guanidyl and Tyr4 hydroxyl groups were not important in either case. The β‐turn conformation was predominant in all of the active peptides, proving importance in anti‐plasmodial activity. This approach provides insight for understanding the importance of each amino acid residue on the native angiotensin II structure and a new direction for the design of potential chemotherapeutic agents. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
964.
965.
Would protecting tropical forest fragments provide carbon and biodiversity cobenefits under REDD+?
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Luiz Fernando S. Magnago Ainhoa Magrach William F. Laurance Sebastião V. Martins João Augusto A. Meira‐Neto Marcelo Simonelli David P. Edwards 《Global Change Biology》2015,21(9):3455-3468
Tropical forests store vast amounts of carbon and are the most biodiverse terrestrial habitats, yet they are being converted and degraded at alarming rates. Given global shortfalls in the budgets required to prevent carbon and biodiversity loss, we need to seek solutions that simultaneously address both issues. Of particular interest are carbon‐based payments under the Reducing Emissions from Deforestation and Forest Degradation (REDD+) mechanism to also conserve biodiversity at no additional cost. One potential is for REDD+ to protect forest fragments, especially within biomes where contiguous forest cover has diminished dramatically, but we require empirical tests of the strength of any carbon and biodiversity cobenefits in such fragmented systems. Using the globally threatened Atlantic Forest landscape, we measured above‐ground carbon stocks within forest fragments spanning 13 to 23 442 ha in area and with different degrees of isolation. We related these stocks to tree community structure and to the richness and abundance of endemic and IUCN Red‐listed species. We found that increasing fragment size has a positive relationship with above‐ground carbon stock and with abundance of IUCN Red‐listed species and tree community structure. We also found negative relationships between distance from large forest block and tree community structure, endemic species richness and abundance, and IUCN Red‐listed species abundance. These resulted in positive congruence between carbon stocks and Red‐listed species, and the abundance and richness of endemic species, demonstrating vital cobenefits. As such, protecting forest fragments in hotspots of biodiversity, particularly larger fragments and those closest to sources, offers important carbon and biodiversity cobenefits. More generally, our results suggest that macroscale models of cobenefits under REDD+ have likely overlooked key benefits at small scales, indicating the necessity to apply models that include finer‐grained assessments in fragmented landscapes rather than using averaged coarse‐grained cells. 相似文献
966.
Lizama C Rojas-Benitez D Antonelli M Ludwig A Moreno RD 《Journal of cellular physiology》2012,227(2):829-838
Germ cell apoptosis is important to regulate sperm production in the mammalian testis, but the molecular mechanisms underlying apoptosis are still poorly understood. We have recently shown that in vitro, etoposide induces upregulation of TACE/ADAM17 and ADAM10, two membrane-bound extracellular metalloproteases. Here we show that in vivo these enzymes are involved in etoposide-, but not in heat shock-, induced apoptosis in rat spermatogenesis. Germ cell apoptosis induced by DNA damage was associated with an increase in protein levels and cell surface localization of TACE/ADAM17 and ADAM10. On the contrary, apoptosis of germ cells induced by heat stress, another cell death stimulus, did not change levels or localization of these proteins. Pharmacological in vivo inhibition of TACE/ADAM17 and ADAM10 prevents etoposide-induced germ cell apoptosis. Finally, Gleevec (STI571) a pharmacological inhibitor of p73, a master gene controlling apoptosis induced by etoposide, prevented the increase of TACE/ADAM17 levels. Our results strongly suggest that TACE/ADAM17 participates in in vivo apoptosis of male germ cells induced by DNA damage. 相似文献
967.
Maria Leandra Terencio Carlos Henrique Schneider Maria Claudia Gross Marcelo Ricardo Vicari Eliana Feldberg 《Hydrobiologia》2012,686(1):147-156
Cytogenetic studies involving the family Prochilodontidae have shown that these fish can be characterized by a constant diploid
number and a conserved karyotypic macrostructure. This study focused on comparative physical chromosomal mapping using 18S
and 5S rDNA to compare the species Semaprochilodus insignis and S. taeniurus. Our results indicated the conservation of large number of conventional chromosomal markers. The molecular cytogenetic analyses
of the location of the 18S rDNA indicated the maintenance of a chromosome pair bearing these sites in both species analyzed,
and it appears to be a conserved character among the majority of the species of this family. The stability of the number of
5S ribosomal DNA sites and their chromosomal localization as has been reported for the Prochilodontidae was not, however,
confirmed for S. insignis and S. taeniurus, as these species showed multiple specific rDNA 5S sites. As such, and in spite of the fact that a number of studies indicate
that the family Prochilodontidae has a conserved karyotypic structure, the utilization of molecular tools that use chromosomal
segments as markers revealed that this presumed stability cannot be extended to the genome level for the species S. insignis and S. taeniurus. 相似文献
968.
969.
970.
Ieda de Carvalho Mendes Marcelo Ferreira Fernandes Guilherme Montandon Chaer Fábio Bueno dos Reis Junior 《Plant and Soil》2012,359(1-2):183-195