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1.
Three isozymes specifically concerned with the “branching” of linear polyglucosides have been delected in algae. These enzymes were detected using two-dimensional polyacrylamide gel electrophoresis, and were found to be present in blue-green, red and in green algae. Two isozynies were found in Oscillatoria princeps; three enzymes were present in Spirogyra setiformis, and two and three such enzymes were detected in red algae of the Rhodymenia type. The significance of the multiple forms of this branching enzyme was assessed in light of the type of storage poly-glucosides formed by these plants. The “degree of branching” of the storage sugar appeared to be related to the evolutionary status of these algae. 相似文献
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Mismatch Repair Genes on Chromosomes 2p and 3p Account for a Major Share of Hereditary Nonpolyposis Colorectal Cancer Families Evaluable by Linkage 总被引:17,自引:1,他引:16 下载免费PDF全文
Minna Nystrm-Lahti Ramon Parsons Pertti Sistonen Lea Pylkknen Lauri A. Aaltonen Fredrick S. Leach Stanley R. Hamilton Patrice Watson Earlene Bronson Ramon Fusaro Jennifer Cavalieri Jane Lynch Stephen Lanspa Tom Smyrk Patrick Lynch Thomas Drouhard Kenneth W. Kinzler Bert Vogelstein Henry T. Lynch Albert de la Chapelle Pivi Peltomki 《American journal of human genetics》1994,55(4):659-665
Two susceptibility loci for hereditary nonpolyposis colo-rectal cancer (HNPCC) have been identified, and each contains a mismatch repair gene: MSH2 on chromosome 2p and MLH1 on chromosome 3p. We studied the involvement of these loci in 13 large HNPCC kindreds originating from three different continents. Six families showed close linkage to the 2p locus, and a heritable mutation of the MSH2 gene was subsequently found in four. The 2p-linked kindreds included a family characterized by the lack of extracolonic manifestations (Lynch I syndrome), as well as two families with cutaneous manifestations typical of the Muir-Torre syndrome. Four families showed evidence for linkage to the 3p locus, and a heritable mutation of the MLH1 gene was later detected in three. One 3p-linked kindred was of Amerindian origin. Of the remaining three families studied for linkage, one showed lod scores compatible with exclusion of both MSH2 and MLH1, while lod scores obtained in the other two families suggested exclusion of one HNPCC locus (MSH2 or MLH1) but were uninformative for markers flanking the other locus. Our results suggest that mismatch repair genes on 2p and 3p account for a major share of HNPCC in kindreds that can be evaluated by linkage analysis. 相似文献
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Mitra Azadniv Morton W. Miller Christopher Cox Fredrick Valentine 《Radiation and environmental biophysics》1993,32(1):73-83
Data on 60-Hz electric field (EF) induced reduction in growth rate of plant roots have strongly supported the hypothesis that the effect is related to an EF-induced transmembrane potential (V
i
m). An investigation was undertaken to determine if this hypothesis is also applicable to 60-Hz EF-induced reductions in growth rate of mammalian cells in vitro. Human lymphoblastic (RPMI 1788) and human carcinoma (HeLa) cells were selected for study, the former having a relatively small diameter (11.2 m), and the latter having a relatively large diameter (15.4 tm). The 60-Hz EFs ranged from 430–1200 V/m in the culture medium. The growth rate of RPMI 1788 cells after 4-days was depressed by about 42% at a 60-Hz EF of 1000–1200 V/m with a response threshold occurring at 950 V/m; theV
i
m at the response threshold was 8 mV There was no 60-Hz EF-induced effect on HeLa cell growth rate of aV
i
m of 8 mV (60-Hz EF=700 V/m); a statistically significant effect was achieved atV
i
m of 11 mV (950 V/m). The data support the hypothesis that above a threshold 60-Hz EF,V
i
m acts as the initial signal leading to growth rate reductions. 相似文献
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Summary Male and female embryos develop in an identical fashion during the initial portion of gestation. If the indifferent gonad differentiates into an ovary (or if no gonad is present), a female phenotype is formed. Male phenotypic differentiation, however, requires the presence of an endocrinologically active testis. Two secretion of the fetal testis, Müllerian inhibiting substance and testosterone, are responsible for male development. Studies of single gene mutations that interfere with androgen action indicate that testosterone itself is responsible for virilization of the Wolffian duct system into the epididymis, vas deferens, and seminal vesicle, whereas the testosterone metabolite dihydrotestosterone induces development of the prostate and male external genitalia. Thus, impairment of dihydrotestosterone formation results in a characteristic phenotype consisting of predominantly female external genitalia but normally virilized Wolffian ducts. The molecular mechanisms by which testosterone and dihydrotestosterone act during fetal development appear to involve the same high affinity receptor, a protein that transports both testosterone and dihydrotestosterone to the nucleus of target cells. When this receptor is either absent, deficient, or structurally abnormal, the actions of both testosterone and dihydrotestosterone are impaired, and the resulting developmental anomalies involve both internal and external genital structures.The original work described in this review was supported by grant AM 03892 from the National Institutes of Health 相似文献
6.
Fredrick C. Colley Lie Kian Joe Viqar Zaman E.U. Canning 《Journal of invertebrate pathology》1975,26(1):11-20
A nuclear-polyhedrosis virus (NPV) of the silkworm, Bombyx mori, which forms an icosahedral inclusion body, was transmitted to larvae of the rice stem borer, Chilo suppressalis. Serial passages of Bombyx NPV in the alternate host by injecting the supernatant of diseased hemolymph produced inclusion bodies with cuboidal and other shapes that differed from the original shape formed in Bombyx. These different shapes increased with times of passages, and after the twelfth passage, only cuboidal inclusion bodies were formed. The icosahedral inclusion bodies in B. mori and the cuboidal inclusion bodies in C. suppressalis occluded singly enveloped virions of the same size (350 × 75 nm), but the cuboidal inclusion bodies contained only a few virions and a large number of membraneous spherical structures. The formation process of the cuboidal inclusion body differed from that of the icosahedral. At first, irregularly branched inclusion bodies containing “vacant” spaces appeared in the infected nuclei. The bodies grew larger with the deposition of protein in the spaces between the branches, and this was accompanied with the occlusion of a large number of membraneous structures formed in the vicinity of the inclusion bodies, which became cuboidal in shape. 相似文献
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Ziyaad Valley-Omar Fredrick Nindo Maanda Mudau Marvin Hsiao Darren Patrick Martin 《PloS one》2015,10(11)
Traditional modes of investigating influenza nosocomial transmission have entailed a combination of confirmatory molecular diagnostic testing and epidemiological investigation. Common hospital-acquired infections like influenza require a discerning ability to distinguish between viral isolates to accurately identify patient transmission chains. We assessed whether influenza hemagglutinin sequence phylogenies can be used to enrich epidemiological data when investigating the extent of nosocomial transmission over a four-month period within a paediatric Hospital in Cape Town South Africa. Possible transmission chains/channels were initially determined through basic patient admission data combined with Maximum likelihood and time-scaled Bayesian phylogenetic analyses. These analyses suggested that most instances of potential hospital-acquired infections resulted from multiple introductions of Influenza A into the hospital, which included instances where virus hemagglutinin sequences were identical between different patients. Furthermore, a general inability to establish epidemiological transmission linkage of patients/viral isolates implied that identified isolates could have originated from asymptomatic hospital patients, visitors or hospital staff. In contrast, a traditional epidemiological investigation that used no viral phylogenetic analyses, based on patient co-admission into specific wards during a particular time-frame, suggested that multiple hospital acquired infection instances may have stemmed from a limited number of identifiable index viral isolates/patients. This traditional epidemiological analysis by itself could incorrectly suggest linkage between unrelated cases, underestimate the number of unique infections and may overlook the possible diffuse nature of hospital transmission, which was suggested by sequencing data to be caused by multiple unique introductions of influenza A isolates into individual hospital wards. We have demonstrated a functional role for viral sequence data in nosocomial transmission investigation through its ability to enrich traditional, non-molecular observational epidemiological investigation by teasing out possible transmission pathways and working toward more accurately enumerating the number of possible transmission events. 相似文献