全文获取类型
收费全文 | 353篇 |
免费 | 44篇 |
出版年
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 6篇 |
2018年 | 8篇 |
2017年 | 12篇 |
2016年 | 15篇 |
2015年 | 23篇 |
2014年 | 19篇 |
2013年 | 25篇 |
2012年 | 18篇 |
2011年 | 14篇 |
2010年 | 10篇 |
2009年 | 4篇 |
2008年 | 16篇 |
2007年 | 11篇 |
2006年 | 12篇 |
2005年 | 11篇 |
2004年 | 6篇 |
2003年 | 13篇 |
2002年 | 9篇 |
2001年 | 12篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 9篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 10篇 |
1987年 | 4篇 |
1986年 | 8篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1976年 | 2篇 |
1974年 | 3篇 |
1973年 | 9篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有397条查询结果,搜索用时 15 毫秒
51.
In Malaysia, tissue banking activities began in Universiti Sains Malaysia (USM) Tissue Bank in early 1990s. Since then a few
other bone banks have been set up in other government hospitals and institutions. However, these banks are not governed by
the national authority. In addition there is no requirement set by the national regulatory authority on coding and traceability
for donated human tissues for transplantation. Hence, USM Tissue Bank has taken the initiatives to adopt a system that enables
the traceability of tissues between the donor, the processed tissue and the recipient based on other international standards
for tissue banks. The traceability trail has been effective and the bank is certified compliance to the international standard
ISO 9001:2008. 相似文献
52.
Batai (Falcataria moluccana) is a valuable tree species for forest plantations in Malaysia and Indonesia. Since 1993, a gall rust disease has caused
severe damage to all growth stages, from seedlings in the nursery to mature trees in the field. To identify the fungus causing
gall rust disease on F. moluccana in Malaysia and Indonesia, study of the mode of infection and changes in the anatomy of infected cells were carried out in
the anatomy laboratory. The disease in Malaysia and Indonesia is caused by Uromycladium tepperianum. The fungus produces three longitudinally ridged teliospores on each head, with spores measuring 13–20 μm wide and 17–28 μm
long. The fungus is microcyclic, completing its entire life cycle on F. moluccana. This study confirmed that the teliospores themselves cannot infect the host. Under favorable conditions, about 10 h after
inoculation, teliospores germinate to produce basidiospores that form penetration pegs about 6 h later, and it is this peg
which penetrates the host cells directly through the epidermis. Pycnia, recognized as small brown pustules, break through
the epidermis about 7 days after inoculation. 相似文献
53.
Abílio VC Vera JA Ferreira LS Duarte CR Martins CR Torres-Leite D Ribeiro Rde A Frussa-Filho R 《Life sciences》2003,72(26):3003-3015
This study examines the effects of melatonin on dopaminergic supersensitivity induced by long-term treatment with haloperidol in rats. Enhancements of spontaneous general activity in an open-field and of stereotyped behavior induced by apomorphine after abrupt withdrawal from long-term treatment with haloperidol were used as experimental parameters for dopaminergic supersensitivity. Experiment 1 was conducted to investigate the effects of melatonin on the development of dopaminergic supersensitivity, and experiment 2 was conducted to investigate the effects of melatonin on the development as well as on expression of dopaminergic supersensitivity. Rats of both experiments were long-term treated with saline or haloperidol concomitant to saline or melatonin. In experiment 1 behavioral observations were performed after abrupt withdrawal from long-term treatment. In experiment 2 behavioral observations were performed 1 hour after an acute injection of saline or melatonin, administered after the abrupt withdrawal from long-term treatment. Both behavioral parameters used showed the development of central dopaminergic supersensitivity in rats treated with haloperidol since 24 hours after abrupt withdrawal. Concomitant treatment with melatonin intensified haloperidol-induced dopaminergic supersensitivity, observed 72 hours after withdrawal. Melatonin treatment per se also induced behavioral supersensitivity evaluated by both open-field and stereotyped behaviors, although it was more fugacious than that presented by haloperidol. Acute treatment with melatonin reverted the enhancement of the haloperidol-induced dopaminergic supersensitivity produced by concomitant long-term treatment with melatonin, as well as melatonin-induced dopaminergic supersensitivity per se. Our results support previous evidence of antidopaminergic effects of melatonin and demonstrate that repeated administration of this hormone modifies the plasticity of behaviors mediated by central dopaminergic systems. 相似文献
54.
Satoshi Maruyama Manami Itagaki Hiroko Ida-Yonemochi Takehiko Kubota Manabu Yamazaki Tatsuya Abé Hiromasa Yoshie Jun Cheng Takashi Saku 《Histochemistry and cell biology》2014,142(3):297-305
The aim of this study was to demonstrate the presence of intraepithelial stroma represented by extracellular matrix (ECM) deposits in the junctional epithelium to clarify its function as a scaffold for leukocyte migration through epithelial cells. Twenty-three biopsy specimens from the gingiva including the junctional epithelium were examined to determine comparative protein and gene level expression profiles for keratin and ECM molecules between the junctional epithelium and the gingival epithelium using immunohistochemistry and in situ hybridization. Intraepithelial leukocyte types and frequencies were also determined and compared between the junctional and gingival epithelia. In the junctional epithelium, which was positive for keratin 19, perlecan was strongly deposited in intercellular space of the whole epithelial layer, while it was faintly positive around the parabasal layer of the gingival epithelium. Perlecan mRNA signals were enhanced to a greater degree in both epithelial and inflammatory cells within the junctional epithelium. In the junctional epithelium, greater numbers of neutrophils and macrophages were found as compared with the gingival epithelium. Our results showed that perlecan is the primary ECM molecule comprising intraepithelial stroma of the junctional epithelium, in which leukocytes may migrate on ECM scaffolds in intercellular space toward the surface of the gingival sulci or pockets. 相似文献
55.
56.
Ecological restoration of rich fens in Europe and North America: from trial and error to an evidence‐based approach
下载免费PDF全文
![点击此处可从《Biological reviews of the Cambridge Philosophical Society》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Leon P. M. Lamers Melanie A. Vile Ab P. Grootjans Mike C. Acreman Rudy van Diggelen Martin G. Evans Curtis J. Richardson Line Rochefort Annemieke M. Kooijman Jan G. M. Roelofs Alfons J. P. Smolders 《Biological reviews of the Cambridge Philosophical Society》2015,90(1):182-203
Fens represent a large array of ecosystem services, including the highest biodiversity found among wetlands, hydrological services, water purification and carbon sequestration. Land‐use change and drainage has severely damaged or annihilated these services in many parts of North America and Europe; restoration plans are urgently needed at the landscape level. We review the major constraints on the restoration of rich fens and fen water bodies in agricultural areas in Europe and disturbed landscapes in North America: (i) habitat quality problems: drought, eutrophication, acidification, and toxicity, and (ii) recolonization problems: species pools, ecosystem fragmentation and connectivity, genetic variability, and invasive species; and here provide possible solutions. We discuss both positive and negative consequences of restoration measures, and their causes. The restoration of wetland ecosystem functioning and services has, for a long time, been based on a trial‐and‐error approach. By presenting research and practice on the restoration of rich fen ecosystems within agricultural areas, we demonstrate the importance of biogeochemical and ecological knowledge at different spatial scales for the management and restoration of biodiversity, water quality, carbon sequestration and other ecosystem services, especially in a changing climate. We define target processes that enable scientists, nature managers, water managers and policy makers to choose between different measures and to predict restoration prospects for different types of deteriorated fens and their starting conditions. 相似文献
57.
Human recombinant stem cell factor promotes spermatogonial proliferation,but not meiosis initiation in organ culture of newt testis fragments 总被引:3,自引:0,他引:3
Abé K Jin Y Yamamoto T Abé S 《Biochemical and biophysical research communications》2002,294(3):695-699
We previously showed that mammalian FSH stimulates the proliferation of newt spermatogonia and induces their differentiation into primary spermatocytes in vitro. In the current study, to examine a possibility that stem cell factor (SCF) is involved in the proliferation of newt spermatogonia and/or their differentiation into primary spermatocytes, human recombinant SCF (rhSCF) was added to organ culture of testicular fragments. rhSCF was found to stimulate the spermatogonial proliferation and the spermatogonia progressed to the seventh generation that is the penultimate stage before primary spermatocyte stage. However, the spermatogonia did not differentiate into primary spermatocytes, but instead died of apoptosis. These results indicate that rhSCF promotes the proliferation of newt spermatogonia, but not the initiation of meiosis. 相似文献
58.
Lovisa Wennerström Linda Laikre Nils Ryman Fred M. Utter Nurul Izza Ab Ghani Carl André Jacquelin DeFaveri Daniel Johansson Lena Kautsky Juha Merilä Natalia Mikhailova Ricardo Pereyra Annica Sandström Amber G. F. Teacher Roman Wenne Anti Vasemägi Małgorzata Zbawicka Kerstin Johannesson Craig R. Primmer 《Biodiversity and Conservation》2013,22(13-14):3045-3065
Information on spatial and temporal patterns of genetic diversity is a prerequisite to understanding the demography of populations, and is fundamental to successful management and conservation of species. In the sea, it has been observed that oceanographic and other physical forces can constitute barriers to gene flow that may result in similar population genetic structures in different species. Such similarities among species would greatly simplify management of genetic biodiversity. Here, we tested for shared genetic patterns in a complex marine area, the Baltic Sea. We assessed spatial patterns of intraspecific genetic diversity and differentiation in seven ecologically important species of the Baltic ecosystem—Atlantic herring (Clupea harengus), northern pike (Esox lucius), European whitefish (Coregonus lavaretus), three-spined stickleback (Gasterosteus aculeatus), nine-spined stickleback (Pungitius pungitius), blue mussel (Mytilus spp.), and bladderwrack (Fucus vesiculosus). We used nuclear genetic data of putatively neutral microsatellite and SNP loci from samples collected from seven regions throughout the Baltic Sea, and reference samples from North Atlantic areas. Overall, patterns of genetic diversity and differentiation among sampling regions were unique for each species, although all six species with Atlantic samples indicated strong resistence to Atlantic-Baltic gene-flow. Major genetic barriers were not shared among species within the Baltic Sea; most species show genetic heterogeneity, but significant isolation by distance was only detected in pike and whitefish. These species-specific patterns of genetic structure preclude generalizations and emphasize the need to undertake genetic surveys for species separately, and to design management plans taking into consideration the specific structures of each species. 相似文献
59.
Sequence homologies within the 5'' end region of the estrogen-controlled vitellogenin gene in Xenopus and chicken. 总被引:8,自引:2,他引:8
下载免费PDF全文
![点击此处可从《The EMBO journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
P Walker M Brown-Luedi J E Germond W Wahli F C Meijlink A D van het Schip H Roelink M Gruber G Ab 《The EMBO journal》1983,2(12):2271-2279
In oviparous vertebrates vitellogenin, the precursor of the major yolk proteins, is synthesized in the liver of mature females under the control of estrogen. We have established the organization and primary structure of the 5' end region of the Xenopus laevis vitellogenin A2 gene and of the major chicken vitellogenin gene. The first three homologous exons have exactly the same length in both species, namely 53, 21 and 152 nucleotides, and present an overall sequence homology of 60%. In both species, the 5'-non-coding region of the vitellogenin mRNA measures only 13 nucleotides, nine of which are conserved. In contrast, the corresponding introns of the Xenopus and the chicken vitellogenin gene show no significant sequence homology. Within the 500 nucleotides preceding the 5' end of the genes, at least six blocks with sequence homologies of greater than 70% were detected. It remains to be demonstrated which of these conserved sequences, if any, are involved in the hormone-regulated expression of the vitellogenin genes. 相似文献
60.