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21.
Pramod B. Shinde Ah Reum Han Jaeyong Cho So Ra Lee Yeon Hee Ban Young Ji Yoo Eun Ji Kim Eunji Kim Myoung-Chong Song Je Won Park Dong Gun Lee Yeo Joon Yoon 《Journal of biotechnology》2013
Expression plasmids carrying different deoxysugar biosynthetic gene cassettes and the gene encoding a substrate-flexible glycosyltransferase DesVII were constructed and introduced into Streptomyces venezuelae YJ003 mutant strain bearing a deletion of a desosamine biosynthetic (des) gene cluster. The resulting recombinants produced macrolide antibiotic YC-17 analogs possessing unnatural sugars replacing native d-desosamine. These metabolites were isolated and further purified using chromatographic techniques and their structures were determined as d-quinovosyl-10-deoxymethynolide, l-rhamnosyl-10-deoxymethynolide, l-olivosyl-10-deoxymethynolide, and d-boivinosyl-10-deoxymethynolide on the basis of 1D and 2D NMR and MS analyses and the stereochemistry of sugars was confirmed using coupling constant values and NOE correlations. Their antibacterial activities were evaluated in vitro against erythromycin-susceptible and -resistant Enterococcus faecium and Staphylococcus aureus. Substitution with l-rhamnose displayed better antibacterial activity than parent compound YC-17 containing native sugar d-desosamine. The present study on relationships between chemical structures and antibacterial activities could be useful in generation of novel advanced antibiotics utilizing combinatorial biosynthesis approach. 相似文献
22.
Jin Bae Weon Hyun-Jeong Ko Choong Je Ma 《Bioorganic & medicinal chemistry letters》2013,23(24):6732-6736
We isolated 2,3-dihydroxy-4-methoxyacetophenone, a neuroprotective compound from Cynenchum paniculatum in our previous study.The present study was conducted to investigate the possible neuroprotective effect of 2,3-dihydroxy-4-methoxyacetophenone that has been previously isolated from Cynenchum paniculatum on hippocampal neuronal cell line, HT22 cells and its possible cognitive-enhancing effect on scopolamine-induced amnesia in mice.Neuroprotective effect against glutamate-induced neurotoxicity in HT22 cells was evaluated by MTT assay. Also, cognitive enhancing effect against scopolamine (1 mg/kg, ip) induced learning and memory deficit was measured by Morris water maze test. Oral administered of 2,3-dihydroxy-4-methoxyacetophenone (1, 10, 20, 40 and 50 mg/kg) to amnesic mice induced by scopolamine. In Morris water maze test, 2,3-dihydroxy-4-methoxyacetophenone (50 mg/kg) improved the impairment of spatial memory induced by scopolamine. 2,3-Dihydroxy-4-methoxyacetophenone protect HT22 cells on glutamate induced cell-death in a dose-dependent manner (EC50 value: 10.94 μM). Furthermore, 2,3-dihydroxy-4-methoxyacetophenone was found to inhibit [Ca2+] accumulation in HT22 cells and had antioxidantive activity. The results showed that 2,3-dihydroxy-4-methoxyacetophenone exert neuroprotective and cognitive-enhancing activities through its antioxidant activity. We suggest that 2,3-dihydroxy-4-methoxyacetophenone improves cognitive function and may be helpful for the treatment of Alzheimer’s disease. 相似文献
23.
Mojca Jež Tuba Bas Matija Veber Andrej Košir Tanja Dominko Raymond Page Primož Rožman 《Histochemistry and cell biology》2013,139(1):195-204
Immunocytochemistry is a powerful tool for detection and visualization of specific molecules in living or fixed cells, their localization and their relative abundance. One of the most commonly used fluorescent DNA dyes in immunocytochemistry applications is 4′,6-diamidino-2-phenylindole dihydrochloride, known as DAPI. DAPI binds strongly to DNA and is used extensively for visualizing cell nuclei. It is excited by UV light and emits characteristic blue fluorescence. Here, we report a phenomenon based on an apparent photoconversion of DAPI that results in detection of a DAPI signal using a standard filter set for detection of green emission due to blue excitation. When a sample stained with DAPI only was first imaged with the green filter set (FITC/GFP), only a weak cytoplasmic autofluorescence was observed. Next, we imaged the sample with a DAPI filter set, obtaining a strong nuclear DAPI signal as expected. Upon reimaging the same samples with a FITC/GFP filter set, robust nuclear fluorescence was observed. We conclude that excitation with UV results in a photoconversion of DAPI that leads to detection of DAPI due to excitation and emission in the FITC/GFP channel. This phenomenon can affect data interpretation and lead to false-positive results when used together with fluorochrome-labeled nuclear proteins detected with blue excitation and green emission. In order to avoid misinterpretations, extra precaution should be taken to prepare staining solutions with low DAPI concentration and DAPI (UV excitation) images should be acquired after all other higher wavelength images. Of various DNA dyes tested, Hoechst 33342 exhibited the lowest photoconversion while that for DAPI and Hoechst 33258 was much stronger. Different fixation methods did not substantially affect the strength of photoconversion. We also suggest avoiding the use of mounting medium with high glycerol concentrations since glycerol showed the strongest impact on photoconversion. This photoconversion effect cannot be avoided even when using narrow bandpass filter sets. 相似文献
24.
The human B12 trafficking chaperone hCblC is well conserved in mammals and non-mammalian eukaryotes. However, the C-terminal ∼40 amino acids of hCblC vary significantly and are predicted to be deleted by alternative splicing of the encoding gene. In this study, we examined the thermostability of the bovine CblC truncated at the C-terminal variable region (t-bCblC) and its regulation by glutathione. t-bCblC is highly thermolabile (Tm = ∼42℃) similar to the full-length protein (f-bCblC). However, t-bCblC is stabilized to a greater extent than f-bCblC by binding of reduced glutathione (GSH) with increased sensitivity to GSH. In addition, binding of oxidized glutathione (GSSG) destabilizes t-bCblC to a greater extent and with increased sensitivity as compared to f-bCblC. These results indicate that t-bCblC is a more sensitive form to be regulated by glutathione than the full-length form of the protein. [BMB Reports 2013; 46(3): 169-174] 相似文献
25.
Yong Wang Jae Young Choi Jong Yul Roh Xue Ying Tao Qin Liu Joo Hyun Lee Jae Su Kim Woo Jin Kim Yeon Ho Je 《Entomological Research》2013,43(1):63-69
Baculovirus chitinase gene (chiA) is a late gene essential for liquefying the host insect at a late stage of infection for its hydrolyzing chitin function. In a previous report, baculovirus ChiA has been shown to offer many interesting new opportunities for pest control. Recently, a putative chiA gene was identified in the Korean isolate of the Spodoptera litura nucleopolyhedorvirus (SpliMNPV‐K1) genome. The open reading frame (ORF) contains 1692 nucelotides and encodes a protein of 563 amino acids with a predicted molecular weight of about 62.6 kDa. To study the insecticidal activity of ChiA from SpliMNPV‐K1, we constructed a recombinant AcMNPV, Ap‐SlChiA, which is designed to express the ChiA under the control of a polyhedrin promoter. Western blot analysis indicated that ChiA was successfully expressed by this recombinant virus. Chitinase assay revealed that the chitobiosidase and endochitinase activity of the recombinant virus was 2.5‐ and 3.9‐flods higher than those of wild‐type AcMNPV, respectively. In addition, the recombinant virus showed higher evident insecticidal activity against 3rd instar larvae of Spodotera exigua than that of the AcMNPV. These results suggest that the chiA gene from SpliMNPV‐K1 could be successfully applied to improve pathogenicity of baculoviruses. 相似文献
26.
Sung Ji Choi Ik Jae Shin Kang-Hoon Je Eun Kyoung Min Eun Ji Kim Hee-Sun Kim Senyon Choe Dong-Eog Kim Dong Kun Lee 《PloS one》2013,8(3)
Although both glucose deprivation and hypoxia have been reported to promote cascades of biological alterations that lead to induction of inflammatory mediators, we hypothesized that glucose deprivation and hypoxia might show neutral, synergistic or antagonistic effects to each other on gene expression of inflammatory mediators depending on the regulatory components in their promoters. Gene expression of interleukin 6 (IL-6) was analyzed by real-time PCR, ELISA, or Western blot. Effects of glucose deprivation and/or hypoxia on activation of signaling pathways were analyzed by time-dependent phosphorylation patterns of signaling molecules. We demonstrate that hypoxia antagonized the effects of glucose deprivation on induction of IL-6 gene expression in microglia, macrophages, and monocytes. Hypoxia also antagonized thapsigargin-induced IL-6 gene expression. Hypoxia enhanced phosphorylation of Akt, and inhibition of Akt was able to reverse the effects of hypoxia on IL-6 gene expression. However, inhibition of HIF-1/2α did not reverse the effects of hypoxia on IL-6 gene expression. In addition, phosphorylation of p38, but not JNK, was responsible for the effects of glucose deprivation on IL-6 gene expression. 相似文献
27.
Mohammad Ali Amanda K. Debes Francisco J. Luquero Deok Ryun Kim Je Yeon Park Laura Digilio Byomkesh Manna Suman Kanungo Shanta Dutta Dipika Sur Sujit K. Bhattacharya David A. Sack 《PLoS medicine》2016,13(9)
IntroductionVaccinating a buffer of individuals around a case (ring vaccination) has the potential to target those who are at highest risk of infection, reducing the number of doses needed to control a disease. We explored the potential vaccine effectiveness (VE) of oral cholera vaccines (OCVs) for such a strategy.ConclusionsThese findings suggest that high-level protection can be achieved if individuals living close to cholera cases are living in a high coverage ring. Since this was an observational study including participants who had received two doses of vaccine (or placebo) in the clinical trial, further studies are needed to determine whether a ring vaccination strategy, in which vaccine is given quickly to those living close to a case, is feasible and effective.
Trial registration
ClinicalTrials.gov NCT00289224相似文献28.
Genetic evidence for prevalence of alloparental care in a socially monogamous biparental cichlid fish,Perissodus microlepis,from Lake Tanganyika supports the “selfish shepherd effect” hypothesis 下载免费PDF全文
Alloparental care – care for unrelated young – is rare in animals, and its ecological or evolutionary advantages or, alternative maladaptive nature, remain unclear. We investigate alloparental care in the socially monogamous cichlid fish Perissodus microlepis from Lake Tanganyika that exhibits bi‐parental care. In a genetic parentage analysis, we discovered a surprisingly high percentage of alloparental care represented by brood mixing, extra‐pair paternity and extra‐pair maternity in all broods that we investigated. The percentage of nondescendant juveniles of other parents, i.e., brood mixing, ranged from 5% to 57% (mean = 28%). The distribution of genetic parentage also suggests that this socially monogamous species has, in fact, polygamous mating system. The prevalence of genetically mixed broods can be best explained by two, not mutually exclusive hypotheses on farming‐out and fostering behaviors. In the majority of broods, the sizes of the parents’ own (descendant) offspring were significantly larger than those of the adopted (nondescendant) juveniles, supporting the ‘selfish shepherd effect’ hypothesis, i.e., that foster parents preferentially accept unrelated “smaller or not larger” young since this would tend to lower the predation risks for their own larger offspring. There was also a tendency for larger parents particularly mothers, more so than smaller parents, to care predominantly for their own offspring. Larger parents might be better at defending against cuckoldry and having foreign young dumped into their broods through farming‐out behavior. This result might argue for maladaptive effects of allopatric care for the foster parents that only larger and possibly more experienced pairs can guard against. It needs to be determined why, apparently, the ability to recognize one's own young has not evolved in this species. 相似文献
29.
Je Hyeong Jung Baskaran Kannan Hugo Dermawan Geoffrey W. Moxley Fredy Altpeter 《Plant molecular biology》2016,92(4-5):505-517
Sugarcane (Saccharum spp. hybrids) is a major feedstock for commercial bioethanol production. The recent integration of conversion technologies that utilize lignocellulosic sugarcane residues as well as sucrose from stem internodes has elevated bioethanol yields. RNAi suppression of lignin biosynthetic enzymes is a successful strategy to improve the saccharification of lignocellulosic biomass. 4-coumarate:coenzyme A ligase (4CL) is a key enzyme in the biosynthesis of phenylpropanoid metabolites, such as lignin and flavonoids. Identifying a major 4CL involved in lignin biosynthesis among multiple isoforms with functional divergence is key to manipulate lignin biosynthesis. In this study, two full length 4CL genes (Sh4CL1 and Sh4CL2) were isolated and characterized in sugarcane. Phylogenetic, expression and RNA interference (RNAi) analysis confirmed that Sh4CL1 is a major lignin biosynthetic gene. An intragenic precision breeding strategy may facilitate the regulatory approval of the genetically improved events and was used for RNAi suppression of Sh4CL1. Both, the RNAi inducing cassette and the expression cassette for the mutated ALS selection marker consisted entirely of DNA sequences from sugarcane or the sexually compatible species Sorghum bicolor. Field grown sugarcane with intragenic RNAi suppression of Sh4CL1 resulted in reduction of the total lignin content by up to 16.5?% along with altered monolignol ratios without reduction in biomass yield. Mature, field grown, intragenic sugarcane events displayed 52–76?% improved saccharification efficiency of lignocellulosic biomass compared to wild type (WT) controls. This demonstrates for the first time that an intragenic approach can add significant value to lignocellulosic feedstocks for biofuel and biochemical production. 相似文献
30.