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21.
The T-DNA tagged mutant gene of Arabidopsis thaliana, mei1, produces after meiosis an abnormal tetrad, consisting of five to eight microspores of varying sizes and DNA contents. Plant
DNA flanking the inserted T-DNA was isolated by inverse PCR. An approximately 16-kb DNA fragment spanning the T-DNA insertion
site was isolated by screening a wild-type genomic library, using the plant flanking DNA as a probe. Using RT-PCR and RNA
isolated from very young flower buds, a cDNA fragment was obtained. Nucleotide sequence comparison of the cDNA and the genomic
sequence in this region indicated a gene which contained two introns. The 5′ and 3′ splice sites of neither intron comply
with the :GU...AG: rule. In the mutant, the T-DNA had inserted into one of the introns. The deduced sequence of the MEI1 wild-type gene, which contains 89 amino acids, shows possible similarity with the human acrosin-trypsin inhibitor, HUSI-II,
and is about the same size. Two wild-type DNA fragments, both extending over the T-DNA insertion site, were introduced into
mutant plants by Agrobacterium-mediated transformation and plants were selected for both hygromycin and kanamycin resistance. Several independent male-fertile
transformants were obtained with one of the DNA fragments. The fragment showing complementation of the mutant phenotype indicated
that the sequence with similarity to the acrosin-trypsin inhibitor is MEI1. Within the 16-kb genomic fragment two other genes were identified; one showed no overall similarity to any protein sequence
in the database and the other had almost complete identity with an Arabidopsis-transcribed sequence tag with similarity to ACC oxidase. Double mutants between mei1 and qrt1 were made, permitting better characterization of the mei1 phenotype because the individual microspores continued to be held together after callose dissolution.
Received: 21 April 1998 / Revision accepted: 11 June 1998 相似文献
22.
Maria A. Guimar?es Rosimeire N. de Oliveira Leiz M. C. Véras David F. Lima Yuri D. M. Campelo Stefano Augusto Campos Selma A. S. Kuckelhaus Pedro L. S. Pinto Peter Eaton Ana C. Mafud Yvonne P. Mascarenhas Silmara M. Allegretti Josué de Moraes Aleksandar Loli? Tatjana Verbi? José Roberto S. A. Leite 《PLoS neglected tropical diseases》2015,9(3)
Schistosomiasis is a serious disease currently estimated to affect more that 207 million people worldwide. Due to the intensive use of praziquantel, there is increasing concern about the development of drug-resistant strains. Therefore, it is necessary to search for and investigate new potential schistosomicidal compounds. This work reports the in vivo effect of the alkaloid epiisopiloturine (EPI) against adults and juvenile worms of Schistosoma mansoni. EPI was first purified its thermal behavior and theoretical solubility parameters charaterised. In the experiment, mice were treated with EPI over the 21 days post-infection with the doses of 40 and 200 mg/kg, and 45 days post-infection with single doses of 40, 100 and 300 mg/kg. The treatment with EPI at 40 mg/kg was more effective in adult worms when compared with doses of 100 and 300 mg/kg. The treatment with 40 mg/kg in adult worms reduced parasite burden significantly, lead to reduction in hepatosplenomegaly, reduced the egg burden in faeces, and decreased granuloma diameter. Scanning electron microscopy revealed morphological changes to the parasite tegument after treatment, including the loss of important features. Additionally, the in vivo treatment against juvenile with 40 mg/kg showed a reduction of the total worm burden of 50.2%. Histopathological studies were performed on liver, spleen, lung, kidney and brain and EPI was shown to have a DL50 of 8000 mg/kg. Therefore EPI shows potential to be used in schistosomiasis treatment. This is the first time that schistosomicidal in vivo activity of EPI has been reported. 相似文献
23.
Estefania Peña B. Calvo M. A. Martínez P. Martins T. Mascarenhas R. M. N. Jorge A. Ferreira M. Doblaré 《Biomechanics and modeling in mechanobiology》2010,9(1):35-44
In this paper, the viscoelastic mechanical properties of vaginal tissue are investigated. Using previous results of the authors
on the mechanical properties of biological soft tissues and newly experimental data from uniaxial tension tests, a new model
for the viscoelastic mechanical properties of the human vaginal tissue is proposed. The structural model seems to be sufficiently
accurate to guarantee its application to prediction of reliable stress distributions, and is suitable for finite element computations.
The obtained results may be helpful in the design of surgical procedures with autologous tissue or prostheses. 相似文献
24.
Vivian Flinte Ethel Hentz Barbara Mascarenhas Morgado Anne Caruliny do Monte Lima Gabriel Khattar Ricardo Ferreira Monteiro Margarete Valverde de Macedo 《ZooKeys》2015,(547):119-132
The population phenology of the cassidines, Coptocycla
arcuata and Omaspides
trichroa, and the chrysomeline, Platyphora
axillaris, was studied at Serra dos Órgãos National Park, State of Rio de Janeiro, southeast Brazil. Monthly surveys of larvae and adults were conducted between 2008 and 2011 at approximately 1000 m altitude on their respective host plants, Cordia
polycephala (Boraginaceae), Ipomoea
philomega (Convolvulaceae) and Solanum
scuticum (Solanaceae). This is the first observation of larviparity and host record for Platyphora
axillaris. Although having different life history traits, all species showed similar phenologies. They were abundant from October to March, months of high temperatures and intense rainfall, with two distinct reproductive peaks in the same season. Abundance dropped abruptly during the coldest and driest months, from May to August. Frequently none of these species were recorded during June and July. This phenological pattern is similar to other Chrysomelidae living in subtropical areas of Brazil. Temperature and rainfall appear to be the major factors influencing the fluctuation of these three species. 相似文献
25.
A shell finite element model of the pelvic floor muscles 总被引:3,自引:0,他引:3
d'Aulignac D Martins JA Pires EB Mascarenhas T Jorge RM 《Computer methods in biomechanics and biomedical engineering》2005,8(5):339-347
The pelvic floor gives support to the organs in the abdominal cavity. Using the dataset made public in (Janda et al. J. Biomech. (2003) 36(6), pp. 749-757), we have reconstructed the geometry of one of the most important parts of the pelvic floor, the levator ani, using NURB surfaces. Once the surface is triangulated, the corresponding mesh is used in a finite element analysis with shell elements.Based on the 3D behavior of the muscle we have constructed a shell that takes into account the direction of the muscle fibers and the incompressibility of the tissue. The constitutive model for the isotropic strain energy and the passive strain energy stored in the fibers is adapted from Humphrey's model for cardiac muscles. To this the active behavior of the skeletal muscle is added.We present preliminary results of a simulation of the levator ani muscle under pressure and with active contraction. This research aims at helping simulate the damages to the pelvic floor that can occur after childbirth. 相似文献
26.
27.
Mariana Vaini de Freitas Marcela Ramos de Oliveira Diogo Fernandes dos Santos Rita de Cássia Mascarenhas Netto Sheila Bernardino Fenelon Nilson Penha-Silva 《The Journal of membrane biology》2010,233(1-3):127-134
Multiple sclerosis (MS) probably occurs by oxidative, inflammatory and autoimmune mechanisms. This study investigated the influence of statin on the stability of erythrocyte membranes in MS patients. The population was composed of one group with simvastatin therapy (20 mg/day), another group without statin therapy and a healthy control group. The stability of erythrocytes was evaluated by the half-transition points, H50 and D50, obtained from the curves of hemolysis induced by hypotonic shock and ethanol action, respectively. Erythrocytes of MS patients were less stable against lysis by both chaotropes. This behavior may be merely a consequence of the lifestyle of MS patients or it may be intrinsically associated with the conjunct of factors responsible for the development of the disease. The use of statin by MS patients was associated with lower levels of LDL and total cholesterol, as expected, and with higher stability of erythrocytes against ethanol compared to the values of untreated MS patients. 相似文献
28.
29.
Structure and Interactions of the Cytoplasmic Domain of the Yersinia Type III Secretion Protein YscD
Alicia Gamez Romila Mukerjea Maher Alayyoubi Majid Ghassemian Partho Ghosh 《Journal of bacteriology》2012,194(21):5949-5958
The virulence of a large number of Gram-negative bacterial pathogens depends on the type III secretion (T3S) system, which transports select bacterial proteins into host cells. An essential component of the Yersinia T3S system is YscD, a single-pass inner membrane protein. We report here the 2.52-Å resolution structure of the cytoplasmic domain of YscD, called YscDc. The structure confirms that YscDc consists of a forkhead-associated (FHA) fold, which in many but not all cases specifies binding to phosphothreonine. YscDc, however, lacks the structural properties associated with phosphothreonine binding and thus most likely interacts with partners in a phosphorylation-independent manner. Structural comparison highlighted two loop regions, L3 and L4, as potential sites of interactions. Alanine substitutions at L3 and L4 had no deleterious effects on protein structure or stability but abrogated T3S in a dominant negative manner. To gain insight into the function of L3 and L4, we identified proteins associated with YscD by affinity purification coupled to mass spectrometry. The lipoprotein YscJ was found associated with wild-type YscD, as was the effector YopH. Notably, the L3 and L4 substitution mutants interacted with more YopH than did wild-type YscD. These substitution mutants also interacted with SycH (the specific chaperone for YopH), the putative C-ring component YscQ, and the ruler component YscP, whereas wild-type YscD did not. These results suggest that substitutions in the L3 and L4 loops of YscD disrupted the dissociation of SycH from YopH, leading to the accumulation of a large protein complex that stalled the T3S apparatus. 相似文献
30.
Maya N. Mascarenhas Seth R. Flaxman Ties Boerma Sheryl Vanderpoel Gretchen A. Stevens 《PLoS medicine》2012,9(12)