全文获取类型
收费全文 | 4766篇 |
免费 | 491篇 |
出版年
2023年 | 25篇 |
2022年 | 49篇 |
2021年 | 132篇 |
2020年 | 69篇 |
2019年 | 91篇 |
2018年 | 121篇 |
2017年 | 109篇 |
2016年 | 155篇 |
2015年 | 221篇 |
2014年 | 247篇 |
2013年 | 272篇 |
2012年 | 344篇 |
2011年 | 292篇 |
2010年 | 208篇 |
2009年 | 162篇 |
2008年 | 237篇 |
2007年 | 220篇 |
2006年 | 193篇 |
2005年 | 172篇 |
2004年 | 164篇 |
2003年 | 168篇 |
2002年 | 106篇 |
2001年 | 128篇 |
2000年 | 111篇 |
1999年 | 83篇 |
1998年 | 51篇 |
1997年 | 45篇 |
1996年 | 44篇 |
1995年 | 43篇 |
1994年 | 46篇 |
1993年 | 41篇 |
1992年 | 71篇 |
1991年 | 64篇 |
1990年 | 83篇 |
1989年 | 70篇 |
1988年 | 76篇 |
1987年 | 62篇 |
1986年 | 64篇 |
1985年 | 55篇 |
1984年 | 36篇 |
1983年 | 37篇 |
1982年 | 27篇 |
1981年 | 21篇 |
1980年 | 22篇 |
1979年 | 23篇 |
1978年 | 21篇 |
1977年 | 22篇 |
1976年 | 21篇 |
1974年 | 19篇 |
1973年 | 20篇 |
排序方式: 共有5257条查询结果,搜索用时 15 毫秒
811.
Ian W. Pray Francesco Pizzitutti Gabrielle Bonnet Eloy Gonzales-Gustavson Wayne Wakeland William K. Pan William E. Lambert Armando E. Gonzalez Hector H. Garcia Seth E. ONeal for the Cysticercosis Working Group in Peru. 《PLoS neglected tropical diseases》2021,15(10)
BackgroundThe pork tapeworm (Taenia solium) is a parasitic helminth that imposes a major health and economic burden on poor rural populations around the world. As recognized by the World Health Organization, a key barrier for achieving control of T. solium is the lack of an accurate and validated simulation model with which to study transmission and evaluate available control and elimination strategies. CystiAgent is a spatially-explicit agent based model for T. solium that is unique among T. solium models in its ability to represent key spatial and environmental features of transmission and simulate spatially targeted interventions, such as ring strategy.Methods/Principal findingsWe validated CystiAgent against results from the Ring Strategy Trial (RST)–a large cluster-randomized trial conducted in northern Peru that evaluated six unique interventions for T. solium control in 23 villages. For the validation, each intervention strategy was replicated in CystiAgent, and the simulated prevalences of human taeniasis, porcine cysticercosis, and porcine seroincidence were compared against prevalence estimates from the trial. Results showed that CystiAgent produced declines in transmission in response to each of the six intervention strategies, but overestimated the effect of interventions in the majority of villages; simulated prevalences for human taenasis and porcine cysticercosis at the end of the trial were a median of 0.53 and 5.0 percentages points less than prevalence observed at the end of the trial, respectively.Conclusions/SignificanceThe validation of CystiAgent represented an important step towards developing an accurate and reliable T. solium transmission model that can be deployed to fill critical gaps in our understanding of T. solium transmission and control. To improve model accuracy, future versions would benefit from improved data on pig immunity and resistance, field effectiveness of anti-helminthic treatment, and factors driving spatial clustering of T. solium infections including dispersion and contact with T. solium eggs in the environment. 相似文献
812.
Elisabet Bjanes Reyna Garcia Sillas Rina Matsuda Benjamin Demarco Timothe Fettrelet Alexandra A. DeLaney Opher S. Kornfeld Bettina L. Lee Eric M. Rodríguez Lpez Daniel Grubaugh Meghan A. Wynosky-Dolfi Naomi H. Philip Elise Krespan Dorothy Tovar Leonel Joannas Daniel P. Beiting Jorge Henao-Mejia Brian C. Schaefer Kaiwen W. Chen Petr Broz Igor E. Brodsky 《PLoS pathogens》2021,17(10)
Cell death plays a critical role in inflammatory responses. During pyroptosis, inflammatory caspases cleave Gasdermin D (GSDMD) to release an N-terminal fragment that generates plasma membrane pores that mediate cell lysis and IL-1 cytokine release. Terminal cell lysis and IL-1β release following caspase activation can be uncoupled in certain cell types or in response to particular stimuli, a state termed hyperactivation. However, the factors and mechanisms that regulate terminal cell lysis downstream of GSDMD cleavage remain poorly understood. In the course of studies to define regulation of pyroptosis during Yersinia infection, we identified a line of Card19-deficient mice (Card19lxcn) whose macrophages were protected from cell lysis and showed reduced apoptosis and pyroptosis, yet had wild-type levels of caspase activation, IL-1 secretion, and GSDMD cleavage. Unexpectedly, CARD19, a mitochondrial CARD-containing protein, was not directly responsible for this, as an independently-generated CRISPR/Cas9 Card19 knockout mouse line (Card19Null) showed no defect in macrophage cell lysis. Notably, Card19 is located on chromosome 13, immediately adjacent to Ninj1, which was recently found to regulate cell lysis downstream of GSDMD activation. RNA-seq and western blotting revealed that Card19lxcn BMDMs have significantly reduced NINJ1 expression, and reconstitution of Ninj1 in Card19lxcn immortalized BMDMs restored their ability to undergo cell lysis in response to caspase-dependent cell death stimuli. Card19lxcn mice exhibited increased susceptibility to Yersinia infection, whereas independently-generated Card19Null mice did not, demonstrating that cell lysis itself plays a key role in protection against bacterial infection, and that the increased infection susceptibility of Card19lxcn mice is attributable to loss of NINJ1. Our findings identify genetic targeting of Card19 being responsible for off-target effects on the adjacent gene Ninj1, disrupting the ability of macrophages to undergo plasma membrane rupture downstream of gasdermin cleavage and impacting host survival and bacterial control during Yersinia infection. 相似文献
813.
Joanna Jeleska Jiyoung Lee Andrew J. Manning Donald J. Wolfgeher Youngjoo Ahn George Walters-Marrah Ivan E. Lopez Lissette Garcia Sheri A. McClerklin Richard W. Michelmore Stephen J. Kron Jean T. Greenberg 《PLoS pathogens》2021,17(11)
The plant pathogen Pseudomonas syringae secretes multiple effectors that modulate plant defenses. Some effectors trigger defenses due to specific recognition by plant immune complexes, whereas others can suppress the resulting immune responses. The HopZ3 effector of P. syringae pv. syringae B728a (PsyB728a) is an acetyltransferase that modifies not only components of plant immune complexes, but also the Psy effectors that activate these complexes. In Arabidopsis, HopZ3 acetylates the host RPM1 complex and the Psy effectors AvrRpm1 and AvrB3. This study focuses on the role of HopZ3 during tomato infection. In Psy-resistant tomato, the main immune complex includes PRF and PTO, a RIPK-family kinase that recognizes the AvrPto effector. HopZ3 acts as a virulence factor on tomato by suppressing AvrPto1Psy-triggered immunity. HopZ3 acetylates AvrPto1Psy and the host proteins PTO, SlRIPK and SlRIN4s. Biochemical reconstruction and site-directed mutagenesis experiments suggest that acetylation acts in multiple ways to suppress immune signaling in tomato. First, acetylation disrupts the critical AvrPto1Psy-PTO interaction needed to initiate the immune response. Unmodified residues at the binding interface of both proteins and at other residues needed for binding are acetylated. Second, acetylation occurs at residues important for AvrPto1Psy function but not for binding to PTO. Finally, acetylation reduces specific phosphorylations needed for promoting the immune-inducing activity of HopZ3’s targets such as AvrPto1Psy and PTO. In some cases, acetylation competes with phosphorylation. HopZ3-mediated acetylation suppresses the kinase activity of SlRIPK and the phosphorylation of its SlRIN4 substrate previously implicated in PTO-signaling. Thus, HopZ3 disrupts the functions of multiple immune components and the effectors that trigger them, leading to increased susceptibility to infection. Finally, mass spectrometry used to map specific acetylated residues confirmed HopZ3’s unusual capacity to modify histidine in addition to serine, threonine and lysine residues. 相似文献
814.
Barbara Ben Yamin Sana AhmedSeghir Junya Tomida Emmanuelle Despras Caroline Pouvelle Andrey Yurchenko Jordane Goulas Raphael Corre Quentin Delacour Nathalie Droin Philippe Dessen Didier Goidin Sabine S Lange Sarita Bhetawal Maria Teresa MitjavilaGarcia Giuseppe Baldacci Sergey Nikolaev Jean Charles Cadoret Richard D Wood Patricia L Kannouche 《The EMBO journal》2021,40(21)
815.
Mingzhao Zhu Wayne D. Harshbarger Omar Robles Joanna Krysiak Kenneth G. Hull Sung Wook Cho Robyn D. Richardson Yanyan Yang Andres Garcia Lindsey Spiegelman Bianca Ramirez Christopher T. Wilson Ju Anne Yau James T. Moore Caitlen B. Walker James C. Sacchettini Wenshe R. Liu Stephan A. Sieber Daniel Romo 《Bioorganic & medicinal chemistry》2017,25(11):2901-2916
The proteasome, a validated cellular target for cancer, is central for maintaining cellular homeostasis, while fatty acid synthase (FAS), a novel target for numerous cancers, is responsible for palmitic acid biosynthesis. Perturbation of either enzymatic machine results in decreased proliferation and ultimately cellular apoptosis. Based on structural similarities, we hypothesized that hybrid molecules of belactosin C, a known proteasome inhibitor, and orlistat, a known inhibitor of the thioesterase domain of FAS, could inhibit both enzymes. Herein, we describe proof-of-principle studies leading to the design, synthesis and enzymatic activity of several novel, β-lactone-based, dual inhibitors of these two enzymes. Validation of dual enzyme targeting through activity-based proteome profiling with an alkyne probe modeled after the most potent inhibitor, and preliminary serum stability studies of selected derivatives are also described. These results provide proof of concept for dual targeting of the proteasome and fatty acid synthase-thioesterase (FAS-TE) enabling a new approach for the development of drug-candidates with potential to overcome resistance. 相似文献
816.
An experimental demonstration that house finches add cigarette butts in response to ectoparasites 下载免费PDF全文
Monserrat Suárez‐Rodríguez Constantino Macías Garcia 《Journal of avian biology》2017,48(10):1316-1321
Urban species encounter resources that are uncommon in nature, such as materials found in city waste. Many studies have shown that these can be harmful to wildlife. In Mexico City, house finches bring cigarette butts to their nests, which reduces the amount of ectoparasites, but also induces genotoxic damage in chicks and parents. Yet, the reason for this behaviour is unknown. One possibility is that birds extract the cellulose fibres from discarded butts simply because they resemble feathers. Alternatively, disassembled cigarette butts may be brought to the nests because they repel ectoparasites. Here we tested the latter hypothesis by assessing whether house finches Carpodacus mexicanus increase the amount of cigarette butts in their nests in response to a raise in ectoparasite load. When present, fibres from butts are concentrated in the nest lining. By taking it away, we simultaneously removed most of the butt material and collected the bulk of the tick population infesting each nest, as these parasites cluster in the lining. We removed the bedding of nests when chicks had recently hatched, and randomly assigned each nests to one of the following treatments: 1) addition of live ticks, 2) addition of dead ticks and 3) simulation of tick addition. Females in the live ticks’ treatment added more butt fibres to their nests than parents in control treatments. Additionally, the amount of butt fibres in the original lining also predicted the amount of fibres added after the manipulation. It seems that the tendency to bring to the nest cigarette butts is at least partially a response to current, and perhaps also past, parasite load. 相似文献
817.
Structural basis for rifamycin resistance of bacterial RNA polymerase by the three most clinically important RpoB mutations found in Mycobacterium tuberculosis 下载免费PDF全文
Vadim Molodtsov Nathan T. Scharf Maxwell A. Stefan George A. Garcia Katsuhiko S. Murakami 《Molecular microbiology》2017,103(6):1034-1045
Since 1967, Rifampin (RMP, a Rifamycin) has been used as a first line antibiotic treatment for tuberculosis (TB), and it remains the cornerstone of current short‐term TB treatment. Increased occurrence of Rifamycin‐resistant (RIFR) TB, ~41% of which results from the RpoB S531L mutation in RNA polymerase (RNAP), has become a growing problem worldwide. In this study, we determined the X‐ray crystal structures of the Escherichia coli RNAPs containing the most clinically important S531L mutation and two other frequently observed RIFR mutants, RpoB D516V and RpoB H526Y. The structures reveal that the S531L mutation imparts subtle if any structural or functional impact on RNAP in the absence of RIF. However, upon RMP binding, the S531L mutant exhibits a disordering of the RIF binding interface, which effectively reduces the RMP affinity. In contrast, the H526Y mutation reshapes the RIF binding pocket, generating significant steric conflicts that essentially prevent any RIF binding. While the D516V mutant does not exhibit any such gross structural changes, certainly the electrostatic surface of the RIF binding pocket is dramatically changed, likely resulting in the decreased affinity for RIFs. Analysis of interactions of RMP with three common RIFR mutant RNAPs suggests that modifications to RMP may recover its efficacy against RIFR TB. 相似文献
818.
Length–weight relationships of fish species from Lower Paranapanema River Basin,Upper Paraná River Basin,Brazil 下载免费PDF全文
C. R. S. Ribeiro D. A. Z. Garcia A. D. A. Costa M. H. S. Yabu A. C. R. Casimiro A. P. Vidotto‐Magnoni M. L. Orsi 《Zeitschrift fur angewandte Ichthyologie》2017,33(5):1038-1039
Length–weight relationships were estimated for six fish species occurring in direct tributaries of the Lower Paranapanema River Basin. Data is described for the first time for five species and new measurements are provided for one species in the FishBase database. Studies of fish diversity are critical for species management and conservation, especially in this basin, which has suffered from many anthropical impacts. 相似文献
819.
Regional and temporal variation in diet and provisioning rates suggest weather limits prey availability for an endangered raptor 下载免费PDF全文
Marie‐Sophie Garcia‐Heras François Mougeot Robert E. Simmons Beatriz Arroyo 《Ibis》2017,159(3):567-579
Understanding variation in food requirements of wild animals is of central importance in population ecology and conservation, as it helps to identify where and when food may be limiting. Studies on diet variation or prey provisioning rates may give useful insights when direct information on prey availability is lacking. We assess spatial and temporal variation in the diet of an endangered predator, the Black Harrier Circus maurus. This raptor is endemic to southern Africa and specializes on small mammals but also feeds on birds and reptiles as alternative prey. Using data on 1679 prey identified in 953 pellets collected in inland and coastal regions from 2006 to 2015, we show that diet composition changed little throughout the breeding season in the coastal region, whereas there was a marked seasonal decline in the occurrence of small mammal prey in the inland region, with a concomitant increase in alternative prey. The proportion of small mammals in the diet declined with increasing maximum temperature, the latter being highest at the inland region late in the breeding season. Using camera recordings at nests in 2014, we further analysed daily patterns of prey provisioning to nestlings. A marked reduction in small mammal provisioning rates occurred during the middle of the day in the hotter inland region but not in the cooler coastal region. Reduced availability of the primary prey, small mammals, in hotter conditions, through a reduction in activity or overall abundance, could explain these patterns. Finally, we show a positive relationship between winter rainfall and interannual differences in the proportion of small mammals in the diet of Black Harriers breeding in the coastal region, suggesting relationships between diet and prey abundance that are mediated through rainfall. We discuss the need to consider spatial variation in food availability in conservation strategies. 相似文献
820.
Rafael G. Tonucci Vimala D. Nair P. K. Ramachandran Nair Rasmo Garcia 《Plant and Soil》2017,414(1-2):281-294