全文获取类型
收费全文 | 570篇 |
免费 | 31篇 |
国内免费 | 2篇 |
出版年
2017年 | 5篇 |
2015年 | 7篇 |
2012年 | 7篇 |
2011年 | 6篇 |
2010年 | 15篇 |
2009年 | 14篇 |
2008年 | 8篇 |
2007年 | 13篇 |
2006年 | 16篇 |
2005年 | 10篇 |
2003年 | 5篇 |
2000年 | 5篇 |
1999年 | 10篇 |
1998年 | 7篇 |
1997年 | 10篇 |
1996年 | 10篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 5篇 |
1989年 | 11篇 |
1988年 | 7篇 |
1987年 | 15篇 |
1986年 | 12篇 |
1985年 | 18篇 |
1984年 | 13篇 |
1983年 | 8篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 5篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 15篇 |
1975年 | 9篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 10篇 |
1971年 | 7篇 |
1970年 | 6篇 |
1959年 | 12篇 |
1958年 | 20篇 |
1957年 | 19篇 |
1956年 | 11篇 |
1955年 | 20篇 |
1954年 | 26篇 |
1953年 | 18篇 |
1952年 | 16篇 |
1951年 | 15篇 |
1950年 | 12篇 |
1949年 | 21篇 |
1948年 | 13篇 |
排序方式: 共有603条查询结果,搜索用时 15 毫秒
31.
The cytoskeletal events that assist restitution of the native intestinal epithelium are poorly understood. To enhance our understanding of repair mechanisms in the native intestinal epithelium we assessed the functional role of actin and the temporal and spatial alterations in actin and villin that occur in native enterocytes migrating in response to injury. Using a well-characterizedin vitroUssing chamber model of native intestine epithelial restitution, the actin inhibitor cytochalasin D (CD) was applied to determine the functional importance of actin to restitution as assessed by sensitive electrophysiological means and structural techniques. Additionally we used phalloidin and indirect immunohistochemistry to localize and semi-quantitate F-actin and villin in migrating cells during restitution. We report new data that shows that when cytoskeletal changes were impaired with CD, the epithelial monolayer was re-established in fewer than 20% of CD-treated villi, cells bordering the epithelial defect did not assume the characteristic phenotype associated with migrating cells, and transepithelial resistance did not return to pre-injury levels. F-actin and villin were present at the leading edge of the migrating cells, basolateral F-actin was decreased, and cytoplasmic villin was increased as determined by phalloidin and immunohistochemical methods. We conclude thatin vitrorepair of the native intestinal epithelium is functionally and structurally dependent on major changes in the cytoskeleton of cells involved in re-establishing the epithelial monolayer over a complex extracellular matrix. 相似文献
32.
The taxonomic significance of leaf micromorphology in the genus Eugenia L. (Myrtaceae) 总被引:1,自引:0,他引:1
NOORMA WATI HARON DAVID M. MOORE 《Botanical journal of the Linnean Society. Linnean Society of London》1996,120(3):265-277
Leaf micromorphological features of both the Old and New World representatives of Eugenia L. have been studied by light microscopy and scanning electron microscopy. The leaves are hypostomatic and, in the majority of species, the stomata are raised above the epidermis. Trichomes are usually present on the abaxial surface of the New World species. The patterns of abaxial surface sculpturing and arrangement of outer stomatal rims are unique in the New World species. The majority of the Old W'orld species showed different anticlinal wall patterns on the adaxial and abaxial epidermises. In the majority of the New World species the anticlinal wall patterns are more or less the same except in E. axillaris. The paracytic type of stomata, with a non-prominent T-piece cutinization at the poles of the guard cells, is a characteristic feature of the New World species. The taxonomic significance of these features in identification and elucidation of species from both areas is discussed. 相似文献
33.
Endometrial hyperplasia and irregular shedding of the endometrium comprise the largest group of known causes of functional uterine bleeding.Most patients with functional uterine bleeding have a normal endometrial pattern. In a series of patients with functional uterine bleeding, it was noted that 69.7 per cent of endometrial specimens reported as normal showed evidence of hyalinized tissue which included endometrial glands. Tissue of this type was noted in only 3.5 per cent of curetted specimens from patients without functional uterine bleeding. Diagnostic uterine curettage is the initial step in the management of functional uterine bleeding. Hysterectomy and radiation castration are seldom necessary in the management of functional uterine bleeding and are indicated only under specific circumstances. 相似文献
34.
35.
C. L. REARDON A. C. DOHNALKOVA P. NACHIMUTHU D. W. KENNEDY D. A. SAFFARINI B. W. AREY L. SHI Z. WANG D. MOORE J. S. MCLEAN D. MOYLES M. J. MARSHALL J. M. ZACHARA J. K. FREDRICKSON A. S. BELIAEV 《Geobiology》2010,8(1):56-68
In an effort to improve the understanding of electron transfer mechanisms at the microbe–mineral interface, Shewanella oneidensis MR-1 mutants with in-frame deletions of outer-membrane cytochromes (OMCs), MtrC and OmcA, were characterized for the ability to reduce ferrihydrite (FH) using a suite of microscopic, spectroscopic, and biochemical techniques. Analysis of purified recombinant proteins demonstrated that both cytochromes undergo rapid electron exchange with FH in vitro with MtrC displaying faster transfer rates than OmcA. Immunomicroscopy with cytochrome-specific antibodies revealed that MtrC co-localizes with iron solids on the cell surface while OmcA exhibits a more diffuse distribution over the cell surface. After 3-day incubation of MR-1 with FH, pronounced reductive transformation mineral products were visible by electron microscopy. Upon further incubation, the predominant phases identified were ferrous phosphates including vivianite [Fe3 (PO4 )2 ·8H2 O] and a switzerite-like phase [Mn3 ,Fe3 (PO4 )2 ·7H2 O] that were heavily colonized by MR-1 cells with surface-exposed outer-membrane cytochromes. In the absence of both MtrC and OmcA, the cells ability to reduce FH was significantly hindered and no mineral transformation products were detected. Collectively, these results highlight the importance of the outer-membrane cytochromes in the reductive transformation of FH and support a role for direct electron transfer from the OMCs at the cell surface to the mineral. 相似文献
36.
37.
JERRY D. MOORE 《American anthropologist》2004,106(1):173-176
Architectural Anthropology. Mari-José Amerlinck, ed. Westport, CT: Bergin and Garvey, 2001. 232 pp.
Minaret Building and Apprenticeship in Yemen. Trevor H. J. Marchand. Richmond, Surrey: Curzon Press, 2001. 304 pp. 相似文献
Minaret Building and Apprenticeship in Yemen. Trevor H. J. Marchand. Richmond, Surrey: Curzon Press, 2001. 304 pp. 相似文献
38.
Baart GJ Zomer B de Haan A van der Pol LA Beuvery EC Tramper J Martens DE 《Genome biology》2007,8(7):R136
Background
Neisseria meningitidis is a human pathogen that can infect diverse sites within the human host. The major diseases caused by N. meningitidis are responsible for death and disability, especially in young infants. In general, most of the recent work on N. meningitidis focuses on potential antigens and their functions, immunogenicity, and pathogenicity mechanisms. Very little work has been carried out on Neisseria primary metabolism over the past 25 years. 相似文献39.
Molecules,morphology and Mimeoma scarabs: evolutionary and taxonomic implications for a palm‐associated scarab group 下载免费PDF全文
MATTHEW R. MOORE CRISTIAN F. BEZA‐BEZA DAVID A. WICKELL JAMES B. BECK MARY L. JAMESON 《Systematic Entomology》2015,40(4):891-900
Cyclocephaline scarabs, the second largest tribe of rhinoceros beetles, are important pollinators of early‐diverging angiosperm families in the tropics. The evolutionary history of cyclocephaline genera is poorly resolved and several genera are thought to be nonmonophyletic. We assess the monophyly of Mimeoma Casey, a group of Neotropical palm‐feeding scarabs, and its relationship to Cyclocephala with a phylogenetic analysis of 2899 bp of DNA sequence data and 18 morphological characters. All five species of Mimeoma were included in analyses along with species of Cyclocephala Dejean, Dyscinetus Harold and Tomarus Erichson as outgroup taxa. Nearly complete 28S, 12S and CO1 data were collected from 26 of 29 specimens, of which 16 samples were pinned, museum specimens. 28S data strongly support a nonmonophyletic Mimeoma; mitochondrial data (CO1 and 12S) suggest that Mimeoma species are nested within an apical clade of other Cyclocephala species; combined molecular and morphological data identify two strongly supported clades of Mimeoma species but do not support their sister relationship. Combined data show that Mimeoma species are nested within Cyclocephala, thus rendering Cyclocephala paraphyletic. Mimeoma is synonymized within Cyclocephala resulting in the following new combinations: Cyclocephala acuta Arrow n.comb ., Cyclocephala englemani (Ratcliffe) n.comb ., Cyclocephala maculata Burmeister n.comb ., Cyclocephala nigra (Endrödi) n.comb . and Cyclocephala signatoides Höhne n.comb . Our results demonstrate that pinned, museum specimens can be used to obtain DNA sequence data (particularly high‐copy gene regions) for evolutionary studies, and provide the first empirical support that host‐plant associations within cyclocephaline scarab clades are conserved at the plant family‐level. 相似文献
40.
Eoghan M Cunnane John JE Mulvihill Hilary E Barrett Michael T Walsh 《Biomedical engineering online》2015,14(Z1):S7