全文获取类型
收费全文 | 677篇 |
免费 | 50篇 |
国内免费 | 1篇 |
出版年
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 22篇 |
2020年 | 7篇 |
2019年 | 14篇 |
2018年 | 26篇 |
2017年 | 21篇 |
2016年 | 20篇 |
2015年 | 35篇 |
2014年 | 33篇 |
2013年 | 49篇 |
2012年 | 57篇 |
2011年 | 60篇 |
2010年 | 32篇 |
2009年 | 26篇 |
2008年 | 34篇 |
2007年 | 33篇 |
2006年 | 35篇 |
2005年 | 35篇 |
2004年 | 24篇 |
2003年 | 24篇 |
2002年 | 15篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 15篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1982年 | 5篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 3篇 |
1969年 | 3篇 |
排序方式: 共有728条查询结果,搜索用时 656 毫秒
71.
Puligundla P Smogrovicova D Obulam VS Ko S 《Journal of industrial microbiology & biotechnology》2011,38(9):1133-1144
There have been numerous developments in ethanol fermentation technology since the beginning of the new millennium as ethanol
has become an immediate viable alternative to fast-depleting crude reserves as well as increasing concerns over environmental
pollution. Nowadays, although most research efforts are focused on the conversion of cheap cellulosic substrates to ethanol,
methods that are cost-competitive with gasoline production are still lacking. At the same time, the ethanol industry has engaged
in implementing potential energy-saving, productivity and efficiency-maximizing technologies in existing production methods
to become more viable. Very high gravity (VHG) fermentation is an emerging, versatile one among such technologies offering
great savings in process water and energy requirements through fermentation of higher concentrations of sugar substrate and,
therefore, increased final ethanol concentration in the medium. The technology also allows increased fermentation efficiency,
without major alterations to existing facilities, by efficient utilization of fermentor space and elimination of known losses.
This comprehensive research update on VHG technology is presented in two main sections, namely VHG brewing, wherein the effects
of nutrients supplementation, yeast pitching rate, flavour compound synthesis and foam stability under increased wort gravities
are discussed; and VHG bioethanol fermentation studies. In the latter section, aspects related to the role of osmoprotectants
and nutrients in yeast stress reduction, substrates utilized/tested so far, including saccharide (glucose, sucrose, molasses,
etc.) and starchy materials (wheat, corn, barley, oats, etc.), and mash viscosity issues in VHG bioethanol production are
detailed. Thereafter, topics common to both areas such as process optimization studies, mutants and gene level studies, immobilized
yeast applications, temperature effect, reserve carbohydrates profile in yeast, and economic aspects are discussed and future
prospects are summarized. 相似文献
72.
Kumar K Desai V Cheng L Khitrov M Grover D Satya RV Yu C Zavaljevski N Reifman J 《PloS one》2011,6(3):e17469
BACKGROUND: The annotation of genomes from next-generation sequencing platforms needs to be rapid, high-throughput, and fully integrated and automated. Although a few Web-based annotation services have recently become available, they may not be the best solution for researchers that need to annotate a large number of genomes, possibly including proprietary data, and store them locally for further analysis. To address this need, we developed a standalone software application, the Annotation of microbial Genome Sequences (AGeS) system, which incorporates publicly available and in-house-developed bioinformatics tools and databases, many of which are parallelized for high-throughput performance. METHODOLOGY: The AGeS system supports three main capabilities. The first is the storage of input contig sequences and the resulting annotation data in a central, customized database. The second is the annotation of microbial genomes using an integrated software pipeline, which first analyzes contigs from high-throughput sequencing by locating genomic regions that code for proteins, RNA, and other genomic elements through the Do-It-Yourself Annotation (DIYA) framework. The identified protein-coding regions are then functionally annotated using the in-house-developed Pipeline for Protein Annotation (PIPA). The third capability is the visualization of annotated sequences using GBrowse. To date, we have implemented these capabilities for bacterial genomes. AGeS was evaluated by comparing its genome annotations with those provided by three other methods. Our results indicate that the software tools integrated into AGeS provide annotations that are in general agreement with those provided by the compared methods. This is demonstrated by a >94% overlap in the number of identified genes, a significant number of identical annotated features, and a >90% agreement in enzyme function predictions. 相似文献
73.
HIV-1 within the CNS produces a neuroAIDS syndrome and may act as a reservoir for reinfection of the peripheral tissues. Study of how HIV-1 crosses the blood-brain barrier (BBB) has been hampered by the lack of nonprimate animal models. However, BBB transport of HIV-1 does not involve any of the known steps conferring species specificity, including binding to CD4 receptors. In vivo and in vitro studies show that HIV-1 and its glycoprotein coat, gp120, are taken up and transported across the BBB of the mouse. Here, we compared the ability of gp120 and HIV-1 to be taken up by isolated brain microvessels (IBM) freshly isolated from mice, from post-mortem human brain, and from mice that had been treated in a manner analogous to the human material (mouse post-mortem). Freshly isolated mouse IBM took up more gp120 and HIV-1 than the human or mouse post-mortem cells. We found no difference between the ability of mouse post-mortem and human IBM to take up either gp120 or HIV-1. Wheatgerm agglutinin has been previously shown to stimulate gp120 and HIV-1 uptake by the BBB; here, it stimulated the uptake of gp120 and of HIV-1 by both mouse post-mortem and human IBM, although stimulated uptake was greatest for fresh mouse IBM. These results show that the mouse can be used to study the initial phases of HIV-1 uptake by the BBB. 相似文献
74.
Molecular characterization of radial spoke subcomplex containing radial spoke protein 3 and heat shock protein 40 in sperm flagella of the ascidian Ciona intestinalis 总被引:1,自引:0,他引:1 下载免费PDF全文
Members of the heat-shock protein (HSP)40 regulate the protein folding activity of HSP70 proteins and help the functional specialization of this molecular chaperone system in various types of cellular events. We have recently identified Hsp40 as a component of flagellar axoneme in the ascidian Ciona intestinalis, suggesting a correlation between Hsp40 related chaperone system and flagellar function. In this study, we have found that Ciona 37-kDa Hsp40 is extracted from KCl-treated axonemes with 0.5 M KI solution and comigrates with radial spoke protein (RSP)3 along with several proteins as a complex through gel filtration and ion exchange columns. Peptide mass fingerprinting with matrix-assisted laser desorption ionization/time of flight/mass spectrometry revealed that other proteins in the complex include a homolog of sea urchin spokehead protein (homolog of RSP4/6), a membrane occupation and recognition nexus repeat protein with sequence similarity with meichroacidin, and a functionally unknown 33-kDa protein. A spoke head protein, LRR37, is not included in the complex, suggesting that the complex constructs the stalk of radial spoke. Immunoelectron microscopy indicates that Hsp40 is localized in the distal portion of spoke stalk, possibly at the junction between spoke head and the stalk. 相似文献
75.
Bono P Cordero E Johnson K Borowsky M Ramesh V Jacks T Hynes RO 《Experimental cell research》2005,308(1):177-187
Layilin is a widely expressed integral membrane hyaluronan receptor, originally identified as a binding partner of talin located in membrane ruffles. We have identified merlin, the neurofibromatosis type 2 tumor suppressor protein and radixin, as other interactors with the carboxy-terminal domain of layilin. We show that the carboxy-terminal domain of layilin is capable of binding to the amino-terminal domain of radixin. An interdomain interaction between the amino- and the carboxy-terminal domains of radixin inhibits its ability to bind to layilin. In the presence of acidic phospholipids, the interdomain interaction of radixin is inhibited and layilin can bind to full-length radixin. In contrast, layilin binds both full-length and amino-terminal merlin-GST fusion proteins without a requirement for phospholipids. Furthermore, layilin antibody can immunoprecipitate merlin, confirming association in vivo between these two proteins, which also display similar subcellular localizations in ruffling membranes. No interaction was observed between layilin and ezrin or layilin and moesin. These findings expand the known binding partners of layilin to include other members of the talin/band 4.1/ERM (ezrin, radixin, and moesin) family of cytoskeletal-membrane linker molecules. This in turn suggests that layilin may mediate signals from extracellular matrix to the cell cytoskeleton via interaction with different intracellular binding partners and thereby be involved in the modulation of cortical structures in the cell. 相似文献
76.
Nitrosation is an important reaction elicited by nitric oxide (NO). To better understand how nitrosation occurs in biological systems, we assessed the effect of myeloperoxidase (MPO), a mediator of inflammation, on nitrosation observed during NO autoxidation. Nitrosation of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ; 10 mum) to 2-nitrosoamino-3-methylimidazo[4,5-f]quinoline (N-NO-IQ) was monitored by HPLC. Using the NO donor spermine NONOate at pH 7.4, MPO potentiated N-NO-IQ formation. The minimum effective quantity of necessary components was 8.5 nm MPO, 0.25 mum H(2)O(2)/min, and 0.024 mum NO/min. Autoxidation was only detected at >/=1.2 mum NO/min. MPO potentiation was not affected by a 40-fold excess flux of H(2)O(2) over NO or less than a 2.4-fold excess flux of NO over H(2)O(2). Potentiation was due to an 8.8-fold increased affinity of MPO-derived nitrosating species for IQ. Autoxidation was inhibited by azide, suggesting involvement of the nitrosonium ion, NO(+). MPO potentiation was inhibited by NADH, but not azide, suggesting oxidative nitrosylation with NO(2)(.) or an NO(2)(.)-like species. MPO nonnitrosative oxidation of IQ with 0.3 mm NO(2)(-) at pH 5.5 was inhibited by azide, but not NADH, demonstrating differences between MPO oxidation of IQ with NO compared with NO(2)(-). Using phorbol ester-stimulated human neutrophils, N-NO-IQ formation was increased with superoxide dismutase and inhibited by catalase and NADH, but not NaN(3). This is consistent with nitrosation potentiation by MPO, not peroxynitrite. Increased N-NO-IQ formation was not detected with polymorphonuclear neutrophils from two unrelated MPO-deficient patients. Results suggest that the highly diffusible stable gas NO could initiate nitrosation at sites of neutrophil infiltration. 相似文献
77.
Ahmed Kamal E. Vijaya Bharathi M. Janaki Ramaiah D. Dastagiri J. Surendranadha Reddy A. Viswanath Farheen Sultana S.N.C.V.L. Pushpavalli Manika Pal-Bhadra Hemant Kumar Srivastava G. Narahari Sastry Aarti Juvekar Subrata Sen Surekha Zingde 《Bioorganic & medicinal chemistry》2010,18(2):526-542
A series of novel quinazolinone linked pyrrolobenzodiazepine (PBD) conjugates were synthesized. These compounds 4a–f and 5a–f were prepared in good yields by linking C-8 of DC-81 with quinazolinone moiety through different alkane spacers. These conjugates were tested for anticancer activity against 11 human cancer cell lines and found to be very potent anticancer agents with GI50 values in the range of <0.1–26.2 μM. Among all the PBD conjugates, one of the conjugate 5c was tested against a panel of 60 human cancer cells. This compound showed activity for individual cancer cell lines with GI50 values of <0.1 μM. The thermal denaturation studies exhibited effective DNA binding ability compared to DC-81 and these results are further supported by molecular modeling studies. The detailed biological aspects of these conjugates on A375 cell line were studied. It was observed that compounds 4b and 5c induced the release of cytochrome c, activation of caspase-3, cleavage of PARP and subsequent cell death. Further, these compounds when treated with A375 cells showed the characteristic features of apoptosis like enhancement in the levels of p53, p21 and p27 inhibition of cyclin dependent kinase-2 (CDK2) and suppression of NF-κB. Moreover, these two compounds 4b and 5c control the cell proliferation by regulating anti-apoptotic genes like (B-cell lymphoma 2) Bcl-2. Therefore, the data generated suggests that these PBD conjugates activate p53 and inhibit NF-κB and thereby these compounds could be promising anticancer agents with better therapeutic potential for the suppression of tumours. 相似文献
78.
Kannan-Thulasiraman P Katsoulidis E Tallman MS Arthur JS Platanias LC 《The Journal of biological chemistry》2006,281(32):22446-22452
Arsenic trioxide (As2O3) is a potent inducer of apoptosis of leukemic cells in vitro and in vivo, but the precise mechanisms by which it mediates such effects are not well defined. We provide evidence that As2O3 induces activation of the mitogen- and stress-activated kinase 1 (MSK1) and downstream phosphorylation of its substrate, histone H3, in leukemia cell lines. Such activation requires upstream engagement of p38 MAPK, as demonstrated by experiments using pharmacological inhibitors of p38 or p38alpha knock-out cells. Arsenic-induced apoptosis was enhanced in cells in which MSK1 expression was decreased using small interfering RNA and in Msk1 knock-out mouse embryonic fibroblasts, suggesting that this kinase is activated in a negative feedback regulatory manner to regulate As2O3 responses. Consistent with this, pharmacological inhibition of MSK1 enhanced the suppressive effects of As2O3 on the growth of primary leukemic progenitors from chronic myelogenous leukemia patients. Altogether, these findings indicate an important role for MSK1 downstream of p38 in the regulation of As2O3 responses. 相似文献
79.
Banks WA Jaeger LB Urayama A Kumar VB Hileman SM Gaskin FS Llanza NV Farr SA Morley JE 《Peptides》2006,27(4):784-796
Antisense potentially can manipulate target gene expression in the brain if it can cross the blood-brain barrier (BBB). We designed three (10mer, 17mer, and 19mer) phosphorothioated antisenses (PS-ODNs) directed against the precursor molecule of methionine enkephalin (Met-Enk), an opiate peptide which suppresses voluntary ethanol drinking. We measured the ability of the antisenses to cross the BBB, accumulate in the brain and CSF, decrease levels of Met-Enk in brain and blood, and affect voluntary ethanol drinking. Each antisense readily crossed the BBB, with 0.07-0.16% of the i.v. dose accumulating per gram of brain. Capillary depletion and CSF sampling each confirmed that the antisenses entered the CNS. Gel electrophoresis of radioactivity recovered from brain and serum showed intact antisense and a higher molecular weight form likely representing antisense bound to protein, but no degradation products. Each antisense molecule and a cocktail of all three reduced Met-Enk levels in brain and serum. Met-Enk levels in the brain were reduced more rapidly and for a longer duration than Met-Enk levels in the serum, indicating a degree of selective targeting to the CNS. Additionally, administration of the cocktail was more effective in reducing Met-Enk levels than any of the individual antisenses. Each antisense increased voluntary ethanol drinking by about 20% and the cocktail increased it by about 80%. Taken together, these results used pharmacokinetic, immunochemical, and behavioral methods to show that PS-ODN antisenses that readily cross the BBB can decrease brain levels of Met-Enk and increase voluntary ethanol drinking. 相似文献
80.
Antitumour activity of crocetin in accordance to tumor incidence, antioxidant status, drug metabolizing enzymes and histopathological studies 总被引:1,自引:0,他引:1
Magesh V Singh JP Selvendiran K Ekambaram G Sakthisekaran D 《Molecular and cellular biochemistry》2006,287(1-2):127-135
Lung cancer is the leading cause of cancer related mortality worldwide. Crocetin, saffron plant derivative known to play a role in cancer chemoprevention. In the present study the effects of crocetin was tested against lung cancer-bearing mice in both pre-initiation and post-initiation periods. Healthy male Swiss albino mice (6–8 weeks old) were used throughout the study. Experiment was designed with the treatment regimen of crocetin [20 mg/kg body weight dissolved in dimethyl sulphoxide (DMSO)] for 4 weeks before (pre-initiation) and from 12th week after Benzo(a) pyrene B(a)p (50 mg/kg body weight) induced lung carcinoma(post-initation). The level of lipid peroxidation (LPO) and marker enzymes markedly increased in carcinogen administered animals, which was brought back to near normal by crocetin treatment. The activities of the enzymic antioxidants and glutathione metabolizing enzymes were decreased in B(a)p induced animals and increased upon drug treatment. Crocetin profoundly reverted back the pathological changes observed in cancerous animals. From the results crocetin proves to scavenge free radical and plays an important role in cellular function. Tumor incidence and histopathological studies proves crocetin is a potent antitumour agent. 相似文献