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81.
We describe a strategy to establish cyanobacterial strains with high levels of H2 production that involves the identification of promising wild-type strains followed by optimization of the selected strains
using genetic engineering. Nostoc sp. PCC 7422 was chosen from 12 other heterocystous strains, because it has the highest nitrogenase activity. We sequenced
the uptake hydrogenase (Hup) gene cluster as well as the bidirectional hydrogenase gene cluster from the strain, and constructed
a mutant (ΔhupL) by insertional disruption of the hupL gene. The ΔhupL mutant produced H2 at 100 μmoles mg chlorophyll a
-1 h-1, a rate three times that of the wild-type. The ΔhupL cells could accumulate H2 to about 29% (v/v) accompanied by O2 evolution in 6 days, under a starting gas phase of Ar + 5% CO2. The presence of 20% O2 in the initial gas phase inhibited H2 accumulation of the ΔhupL cells by less than 20% until day 7. 相似文献
82.
A Takeno A Okamoto K Tori K Oshima H Hirakawa H Toh N Agata K Yamada N Ogasawara T Hayashi T Shimizu S Kuhara M Hattori M Ohta 《Journal of bacteriology》2012,194(17):4767-4768
We report the complete and annotated genome sequence of Bacillus cereus NC7401, a representative of the strain group that causes emetic-type food poisoning. The emetic toxin, cereulide, is produced by a nonribosomal protein synthesis (NRPS) system that is encoded by a gene cluster on a large resident plasmid, pNCcld. 相似文献
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84.
Yoshiba N Yoshiba K Stoetzel C Perrin-Schmitt F Cam Y Ruch JV Hosoya A Ozawa H Lesot H 《Cell and tissue research》2006,324(1):97-104
Tissue inhibitors of metalloproteinases (TIMPs) possess multiple functions, in addition to their matrix metalloproteinase
(MMP) inhibitory activity. The continuously growing incisor of mouse possesses a stem cell compartment at the apical end of
the epithelium (the apical loop) and thus provides an excellent tool to analyze the mechanisms of organogenesis and cytodifferentiation.
To understand the functions of TIMPs in tooth development, we have analyzed the gene expression and protein localization
of TIMP-1, -2, and -3 during mouse incisor development, from embryonic day 13 (E13) to postnatal day 3 (P3). TIMP-1 was present
on the basement membrane during early developmental stages. At P2, TIMP-1 was strongly detected along the apical loop, transiently
disappeared from the basement membrane in the cytodifferentiation zone, and later reappeared at the distal end of functional
ameloblasts. Expression of TIMP-2 protein was restricted to the outer part of the apical loop throughout the examined stages.
At P2, TIMP-2 was present on the basement membrane at the outer part of the apical loop. The dental follicle also expressed
Timp-2, and the corresponding protein was abundant within the extracellular matrix. Timp-3 mRNA was highly expressed in the mesenchyme surrounding the apical loop. During matrix formation, Timp-3 was expressed by subodontoblasts, and the protein was detected in this layer and between odontoblasts. Distinct temporal
and spatial expression patterns of TIMPs suggest divergent functions of these factors in incisor organogenesis.
This work was supported by INSERM, CNRS, ARC, French Ministry of Research (ACI), Japanese Ministry of Education, Culture,
Sports, Science, and Technology, and Niigata University Research Projects. 相似文献
85.
OBJECTIVE: To test the association between a shift in vaginal flora (SVF) and chorioamnionitis in a population with a high prevalence of both conditions. STUDY DESIGN: Subjects were women with Pap smears and placentas examined at the Medical Center of Louisiana, New Orleans. The presence of subchorionitis, chorionitis, chorioamnionitis and necrotizing chorioamnionitis was evaluated blindly on placental tissue sections. The presence of SVF was evaluated on matching cervical Pap smears obtained during gestation. RESULTS: Three hundred twenty-two placentas and the corresponding Pap smears were examined. Chorioamnionitis was identified in 112 placentas. It was not significantly associated with maternal age or ethnicity, but its prevalence was inversely related to gestational age. SVF was observed in 114 Pap smears. It was more common among African Americans than other ethnic groups but was not significantly associated with maternal age or gestational age at delivery. SVF was more often observed in Pap smears collected in early pregnancies than in those collected later. There was no significant association between chorioamnionitis and SVF before and after accounting for ethnicity, maternal age, gestational age at Pap smear collection, and interval between Pap smear collection and delivery. CONCLUSION: SVF had no significant predictive value for chorioamnionitis in our study population. 相似文献
86.
Nishida Y Yokota T Takahashi T Uchihara T Jishage K Mizusawa H 《Biochemical and biophysical research communications》2006,350(3):530-536
Increased oxidative damage is a prominent and early feature in Alzheimer disease (AD). However, whether it is a primary cause or merely a downstream consequence in AD pathology is still unknown. We previously generated alpha-tocopherol transfer protein knockout (Ttpa-/-) mice, in which lipid peroxidation in the brain was significantly increased by complete depletion of alpha-tocopherol (alpha-Toc). Here we crossed AD transgenic (APPsw) model mice (Tg2576) with Ttpa-/- mice. The resulting double-mutant (Ttpa-/- APPsw) mice showed earlier and more severe cognitive dysfunction in the Morris water maze, novel-object recognition, and contextual fear conditioning tests. They also showed increased amyloid beta-peptide (Abeta) deposits in the brain by immunohistochemical analysis, which was ameliorated with alpha-Toc supplementation. In this report we provide clear evidence indicating that chronic lipid peroxidation due to alpha-Toc depletion enhances AD phenotype in a mouse model. 相似文献
87.
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89.
Hormone interactions during lateral root formation 总被引:2,自引:0,他引:2
Lateral root (LR) formation, the production of new roots from parent roots, is a hormone- and environmentally-regulated developmental
process in higher plants. Physiological and genetic studies using Arabidopsis
thaliana and other plant species have revealed the roles of several plant hormones in LR formation, particularly the role of auxin
in LR initiation and primordium development, resulting in much progress toward understanding the mechanisms of auxin-mediated
LR formation. However, hormone interactions during LR formation have been relatively underexamined. Recent studies have shown
that the plant hormones, cytokinin and abscisic acid negatively regulate LR formation whereas brassinosteroids positively
regulate LR formation. On the other hand, ethylene has positive and negative roles during LR formation. This review summarizes
recent findings on hormone-regulated LR formation in higher plants, focusing on auxin as a trigger and on the other hormones
in LR formation, and discusses the possible interactions among plant hormones in this developmental process. 相似文献
90.
Hidehiro Takahashi Naohiro Ohtaki Masae Maeda-Sato Michiko Tanaka Keiko Tanaka Hirofumi Sawa Toyokazu Ishikawa Akihisa Takamizawa Tomohiko Takasaki Hideki Hasegawa Tetsutaro Sata William W. Hall Takeshi Kurata Asato Kojima 《Microbes and infection / Institut Pasteur》2009,11(13):1019-1028
Expression of genes for precursor M (prM) and envelope (E) proteins of West Nile virus (WNV) leads to the production of small, capsidless, and non-infectious virus-like particles (VLPs) possessing the E antigen which is responsible for viral entry and immune protection. It has been reported that processing of the secretion signal affects viral release. We examined the secretion efficiency of VLPs into the culture medium from RK13 or 293 T cells transfected with expression vectors for prM and E proteins of WNV which were constructed to comprise different lengths of signal peptides upstream of the prM-E domain. The number of amino acid residues present in the segment markedly affected the production, processing, and secretion of VLPs. Secreted VLPs possessed both the processed M protein and the glycosylated E protein. In addition, immunization with VLPs induced neutralizing antibodies in C3H/HeN mice. These results indicate that the number of amino acid residues comprising the N-terminus of the signal segment controls the efficiency of assembly, maturation, and release of VLPs in the absence of viral protease, which in turn indicates the potential of VLPs as a candidate for an effective WNV subunit vaccine. 相似文献