全文获取类型
收费全文 | 342篇 |
免费 | 29篇 |
出版年
2022年 | 5篇 |
2021年 | 8篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2017年 | 11篇 |
2016年 | 9篇 |
2015年 | 10篇 |
2014年 | 10篇 |
2013年 | 26篇 |
2012年 | 22篇 |
2011年 | 21篇 |
2010年 | 14篇 |
2009年 | 16篇 |
2008年 | 12篇 |
2007年 | 16篇 |
2006年 | 15篇 |
2005年 | 14篇 |
2004年 | 16篇 |
2003年 | 13篇 |
2002年 | 9篇 |
2001年 | 11篇 |
2000年 | 9篇 |
1999年 | 6篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1991年 | 4篇 |
1990年 | 7篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 3篇 |
1979年 | 10篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1970年 | 2篇 |
1968年 | 3篇 |
1967年 | 4篇 |
1966年 | 2篇 |
1965年 | 1篇 |
1964年 | 4篇 |
1963年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有371条查询结果,搜索用时 453 毫秒
321.
E. Stodůlková M. Kolařík Z. Křesinová M. Kuzma M. Šulc P. Man P. Novák P. Maršík P. Landa J. Olšovská M. Chudíčková S. Pažoutová J. Černý J. Bella M. Flieger 《Folia microbiologica》2009,54(3):179-187
Geosmithia fungi are little known symbionts of bark beetles. Secondary metabolites of lilac colored species G. lavendula and other nine Geosmithia species were investigated in order to elucidate their possible role in the interactions of the fungi with environment. Hydroxylated
anthraquinones (yellow, orange, and red pigments), were found to be the most abundant compounds produced into the medium during
the submerged cultivation. Three main compounds were identified as 1,3,6,8-tetrahydroxyanthraquinone (1), rhodolamprometrin (1-acetyl-2,4,5,7-tetrahydroxyanthraquinone; 2), and 1-acetyl-2,4,5,7,8-pentahydroxyanthraquinone (3). Compounds 2 and 3 (representing the majority of produced metabolites) inhibited the growth of G+-bacteria Staphylococcus aureus and Bacillus subtilis with minimum inhibitory concentration of 64–512 μg/mL. Anti-inflammatory activity detected as inhibition of cyclooxygenase-2
was found only for compound 3 at 1 and 10 μg/mL. Compound 2 interfered with the morphology, compound 3 with cell-cycle dynamics of adherent mammalian cell lines. 相似文献
322.
Freshwater diatom and macroinvertebrate diversity of coastal permanent ponds along a gradient of human impact in a Mediterranean eco-region 总被引:1,自引:1,他引:0
Mediterranean coastal areas are characterised by heavily transformed landscapes and an ever-increasing number of ponds are
subjected to strong alterations. Although benthic diatoms and macroinvertebrates are widely used as indicators in freshwater
ecosystems, little is still known about the diatom communities of lowland freshwater ponds in the Mediterranean region, and,
furthermore, there are few macroinvertebrate-based methods to assess their ecological quality, especially in Italy. This article
undertakes an analysis of benthic diatom and macroinvertebrate communities of permanent freshwater ponds, selected along a
gradient of anthropogenic pressures, to identify community indicators (taxa and/or metrics) useful to evaluate the effect
of human impacts. A series of 21 ponds were sampled along Tyrrhenian coast in central Italy. Five of these ponds, in a good
conservations status and surrounded by woodland were selected as ‘reference sites’ for macroinvertebrates and epipelic diatoms.
The remaining sixteen ponds were located in an agricultural landscape subject to different levels of human impact. The total
number of macroinvertebrate taxa found in each pond was significantly higher in reference sites than in both the intermediate
and heavily degraded ones, whereas the diatom species richness did not result in a good community variable to evaluate the
pond ecological quality. The analysis revealed a substantial difference among the compositions of diatom communities between
reference ponds and degraded ponds. The former were characterised by the presence of several species belonging to genera,
such as Pinnularia sp., Eunotia sp., Stauroneis sp., Neidium sp., all of which were mostly absent from degraded ponds. Furthermore, the taxonomic richnesses of some macroinvetebrate
groups (Odonata, Ephemeroptera, Trichoptera, Coleoptera), and taxa composition attributes of macroinvertebrate communities
(total abundance, percentages of top three dominant taxa, percentages of Pleidae, Ancylidae, Hirudinea, Hydracarina) significantly
correlated with variables linked with anthropogenic pressures. The results of the investigation suggested that diatoms tended
more to reflect water chemistry through changes in community structure, whereas invertebrates responded to physical habitat
changes primarily through changes in taxonomic richness. The methodologies developed for the analysis of freshwater benthic
diatom and macroinvertebrate communities may have a considerable potential as a tool for assessing the ecological status of
this type of water body, complying with the European Union Water Framework Directive 2000/60/EC.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Guest editors: B. Oertli, R. Cereghino, A. Hull & R. Miracle
Pond Conservation: From Science to Practice. 3rd Conference of the European Pond Conservation Network, Valencia, Spain, 14–16
May 2008 相似文献
323.
324.
Koreck A Bella Z Kadocsa E Perenyi A Tiszlavicz L Nemeth I Kiss M Olariu TR Jori J Kemeny L 《Roumanian archives of microbiology and immunology》2010,69(1):20-23
Nasal polyposis (NP) affects 4% of the general population, representing a major health problem. In spite of complex (surgical and medical) treatment, the relapse rate is high and it has a negative impact on the quality of life. Recently we found that intranasal photochemotherapy with ultraviolet A light (PUVA) is effective in allergic rhinitis. In the present study PUVA was administered for 6 weeks in 7 patients with NP. Nasal lavages were performed in all patients before and at the end of the treatment; from four patients a biopsy specimen was also collected. Eosinophils significantly decreased in patients with NP and slightly in a patient who had associated aspirin sensitivity. IL-5 and eosinophil cationic protein (ECP) levels showed a decreasing trend in patients with NP and an increasing trend in patients with associated aspirin sensitivity. Our results suggest that intranasal PUVA might represent a future therapeutic method in a subset of patients with NP. 相似文献
325.
Igor Topol Jack Collins Igor Polyakov Bella Grigorenko Alexander Nemukhin 《Biophysical chemistry》2009
We present results of theoretical studies of the photoabsorption band corresponding to the vertical electronic transition S0–S1 between first two singlet states of the model chromophore from the green fluorescent protein (GFP) in its neutral form. Predictions of quantum chemical approaches including ab initio and semi-empirical approximations are compared for the model systems which mimic the GFP chromophore in different environments. We provide evidences that the protein matrix in GFP accounts for a fairly large shift of about 40 nm in the S0–S1 absorption band as compared to the gas phase. 相似文献
326.
Amedeo Amedei Elena Niccolai Chiara Della Bella Fabio Cianchi Giacomo Trallori Marisa Benagiano Lapo Bencini Marco Bernini Marco Farsi Renato Moretti Gianfranco Del Prete Mario Milco D’Elios 《Cancer immunology, immunotherapy : CII》2009,58(11):1819-1830
Gastric cancer is a significant cause of morbidity and mortality worldwide. Surgical resection remains the primary curative
treatment for gastric adenocarcinoma, but the poor (15–35%) survival rate at 5 years has prompted many studies for new therapeutic
strategies, such as specific immunotherapy. The aim of this study was to analyze the functional properties of the T cell response
to different antigen peptides related to gastric cancer in patients with gastric adenocarcinoma. To this purpose, we have
cloned and characterized tumor-infiltrating T cells (TILs) isolated from the neoplastic gastric tissue samples. A T cell response
specific to different peptides of gastric cancer antigens tested was documented in 17 out of 20 patients, selected for their
HLA-A02 and/or -A24 alleles. Most of the cancer peptide-specific TILs expressed a Th1/Tc1 profile and cytotoxic activity against
target cells. The effector functions of cancer peptide-specific T cells obtained from the peripheral blood of the same patients
were also studied. The majority of peripheral blood peptide-specific T cells also expressed the Th1/Tc1 functional profile.
In conclusion, in most of the patients with gastric adenocarcinoma, a specific type-1 T cell response to gastric cancer antigens
was detectable and would have the potential of hamper tumor cell growth. However, in order to get tumor cell killing in vivo,
the activity and the number of cancer peptide-specific Th1/Tc1 cells probably need to be enhanced by vaccination with the
appropriate cancer antigenic peptides or by injection of the autologus tumor peptide-specific T cells expanded in vitro. 相似文献
327.
An important issue in Metazoan development is to understand the mechanisms that lead to stereotyped patterns of programmed cell death. In particular, cells programmed to die may arise from asymmetric cell divisions. The mechanisms underlying such binary cell death decisions are unknown. We describe here a Drosophila sensory organ lineage that generates a single multidentritic neuron in the embryo. This lineage involves two asymmetric divisions. Following each division, one of the two daughter cells expresses the pro-apoptotic genes reaper and grim and subsequently dies. The protein Numb appears to be specifically inherited by the daughter cell that does not die. Numb is necessary and sufficient to prevent apoptosis in this lineage. Conversely, activated Notch is sufficient to trigger death in this lineage. These results show that binary cell death decision can be regulated by the unequal segregation of Numb at mitosis. Our study also indicates that regulation of programmed cell death modulates the final pattern of sensory organs in a segment-specific manner. 相似文献
328.
329.
330.