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排序方式: 共有590条查询结果,搜索用时 31 毫秒
81.
Gabriel Yarmush Lucas Santos Joshua Yarmush Srivathsan Koundinyan Mubasher Saleem Nir I. Nativ Martin L. Yarmush Francois Berthiaume Timothy J. Maguire Chris Guaghan 《Biomechanics and modeling in mechanobiology》2017,16(4):1095-1102
Donor livers available to transplant for patients with end-stage liver disease are in severe shortage. One possible avenue to expand the donor pool is to recondition livers that would be otherwise discarded due to excessive fat content. Severely steatotic livers (also known as fatty livers) are highly susceptible to ischemia-reperfusion injury and as a result, primary liver non-function post-transplantation. Prior studies in isolated perfused rat livers suggest that “defatting” may be possible in a timeframe of a few hours; thus, it is conceivable that fatty liver grafts could be recovered by machine perfusion to clear stored fat from the organ prior to transplantation. However, studies using hepatoma cells and adult hepatocytes made fatty in culture report that defatting may take several days. Because cell culture studies were done in static conditions, we hypothesized that the defatting kinetics are highly sensitive to flow-mediated transport of metabolites. To investigate this question, we experimentally evaluated the effect of increasing flow rate on the defatting kinetics of cultured HepG2 cells and developed an in silico combined reaction-transport model to identify possible rate-limiting steps in the defatting process. We found that in cultured fatty HepG2 cells, the time required to clear stored fat down to lean control cells can be reduced from 48 to 4–6 h by switching from static to flow conditions. The flow required resulted in a fluid shear of .008 Pa, which did not adversely affect hepatic function. The reaction-transport model suggests that the transport of l-carnitine, which is the carrier responsible for taking free fatty acids into the mitochondria, is the key rate-limiting process in defatting that was modulated by flow. Therefore, we can ensure higher levels of l-carnitine uptake by the cells by choosing flow rates that minimize the limiting mass transport while minimizing shear stress. 相似文献
82.
A flexible framework for conducting nationwide multimedia, multipathway and multireceptor risk assessments (3MRA) under uncertainty was developed to estimate protective chemical concentration limits in a source area. The framework consists of two components: risk assessment and uncertainty analysis. The risk component utilizes linked source, fate/transport, exposure and risk assessment models to estimate the risk exposures for the receptors of concern. Both human and ecological receptors are included in the risk assessment framework. The flexibility of the framework is based on its ability to address problems varying in spatial scales from site-specific to regional and even national levels; and its ability to accommodate varying types of source, fate/transport, exposure and risk assessment models. The uncertainty component of the 3MRA framework is based on a two-stage Monte Carlo methodology. It allows the calculation of uncertainty in risk estimates, and the incorporation of the effects of uncertainty on the determination of regulatory concentration limits as a function of variability and uncertainty in input data, as well as potential errors in fate and transport and risk and exposure models. The framework can be adapted to handle a wide range of multimedia risk assessment problems. Two examples are presented to illustrate its use, and to demonstrate how regulatory decisions can be structured to incorporate the uncertainty in risk estimates. 相似文献
83.
84.
Muhammad Tahir Muhammad Saleem Haider Javed Iqbal Rob William Briddon 《Journal of Phytopathology》2009,157(3):188-193
Pedilanthus tithymaloides (Redbird flower) is an ornamental shrub that occasionally exhibits leaf curl and enation symptoms in Pakistan. Symptoms were shown to be associated with a monopartite begomovirus and a betasatellite. The complete nucleotide sequence of the begomovirus was found to be 2764 nucleotides in length and have the highest nucleotide sequence identity to a begomovirus previously isolated from tomato (90.3% nucleotide sequence identity), followed by Radish leaf curl virus (86.3%). The complete betasatellite sequence was determined to be 1358 nucleotides in length and has the highest sequence identity (97%) with Tobacco leaf curl betasatellite . The analysis shows the begomovirus associated with leaf curl disease of Pedilanthus to be a distinct and previously unreported begomovirus for which the name Pedilanthus leaf curl virus (PedLCV) is proposed. This virus is one of an increasing number of monopartite begomoviruses shown to be associated with a betasatellite. 相似文献
85.
Sarfraz Hussain Muhammad Arshad Baby Shaharoona Muhammad Saleem Azeem Khalid 《World journal of microbiology & biotechnology》2009,25(5):853-858
The rates of biodegradation of endosulfan by P. aeruginosa were determined with different initial endosulfan concentrations (10, 50, 100, 150, 200 and 250 mg l−1) and different growth linked kinetic models were fitted at these concentrations. At 10 mg endosulfan l−1, Monod no growth model was well fitted. Monod with growth model described the biodegradation pattern at an initial concentration
of 50, 100 and 150 mg endosulfan l−1. Significant increases of P. aeruginosa MN2B14 density in broth culture during incubation further support this result. Conversely, zero order kinetic model was well
fitted into the biodegradation data if initial endosulfan concentration was ≥200 mg endosulfan l−1. The kinetics of endosulfan biodegradation by P. aeruginosa MN2B14 in liquid broth was highly dependent upon its initial concentration. The results of this study could be employed for
predicting the persistence of endosulfan in water environment containing P. aeruginosa as an endosulfan degrading bacterium. 相似文献
86.
Dasagrandhi Chakradhar Saleem Javeed Avinash P. Sattur 《Journal of industrial microbiology & biotechnology》2009,36(9):1179-1187
Nigerloxin, a new and potent lipoxygenase inhibitor, was discovered in our laboratory through solid-state fermentation of
wheat bran by Aspergillus niger V. Teigh (MTCC-5166). The aim of this study is to investigate the possibility of using different agro-industrial residues
as nutritional supplements along with wheat bran to enhance the production of nigerloxin. Nigerloxin produced by SSF was quantified
spectrophotometrically at 292 nm. The results indicate that the inhibitor production was influenced by the type of solid substrate
supplemented, moisture content, pH and size of the inoculum. Individually optimized supplements were tested in different combinations
to determine their effects on nigerloxin production. A twofold increase in the production of nigerloxin (4.9 ± 0.3 mg gds−1) was achieved by supplementing wheat bran with 10% w/w sweet lemon peel and 5% v/w methanol at optimized process parameters,
that is, an initial moisture content of 65% v/w and incubation period of 6 days with an initial inoculum size of 2 ml (8 × 105 spores gds−1). Nigerloxin production was stable between pH of 4 and 5. 相似文献
87.
Abdelnoor RV Christensen AC Mohammed S Munoz-Castillo B Moriyama H Mackenzie SA 《Journal of molecular evolution》2006,63(2):165-173
Mitochondrial processes influence a broad spectrum of physiological and developmental events in higher eukaryotes, and their
aberrant function can lead to several familiar disease phenotypes in mammals. In plants, mitochondrial genes directly influence
pollen development and the occurrence of male sterility in natural plant populations. Likewise, in animal systems evidence
accumulates to suggest important mitochondrial functions in spermatogenesis and reproduction. Here we present evidence for
a convergent gene fusion involving a MutS-homologous gene functioning within the mitochondrion and designated Msh1. In only plants and soft corals, the MutS homologue has fused with a homing endonuclease sequence at the carboxy terminus of the protein. However, the endonuclease
domains in the plants and the soft corals are members of different groups. In plants, Msh1 can influence mitochondrial genome organization and male sterility expression. Based on parallels in Msh1 gene structure shared by plants and corals, and their similarities in reproductive behavior, we postulate that this convergent
gene fusion might have occurred in response to coincident adaptive pressures on reproduction.
[Reviewing Editor: Dr. Deborah Charlesworth] 相似文献
88.
Cloning and characterization of deoxymugineic acid synthase genes from graminaceous plants 总被引:2,自引:0,他引:2
Bashir K Inoue H Nagasaka S Takahashi M Nakanishi H Mori S Nishizawa NK 《The Journal of biological chemistry》2006,281(43):32395-32402
Graminaceous plants have evolved a unique mechanism to acquire iron through the secretion of a family of small molecules, called mugineic acid family phytosiderophores (MAs). All MAs are synthesized from l-Met, sharing the same pathway from l-Met to 2'-deoxymugineic acid (DMA). DMA is synthesized through the reduction of a 3'-keto intermediate by deoxymugineic acid synthase (DMAS). We have isolated DMAS genes from rice (OsDMAS1), barley (HvDMAS1), wheat (TaD-MAS1), and maize (ZmDMAS1). Their nucleotide sequences indicate that OsDMAS1 encodes a predicted polypeptide of 318 amino acids, whereas the other three orthologs all encode predicted polypeptides of 314 amino acids and are highly homologous (82-97.5%) to each other. The DMAS proteins belong to the aldo-keto reductase superfamily 4 (AKR4) but do not fall within the existing subfamilies of AKR4 and appear to constitute a new subfamily within the AKR4 group. All of the proteins showed DMA synthesis activity in vitro. Their enzymatic activities were highest at pH 8-9, consistent with the hypothesis that DMA is synthesized in subcellular vesicles. Northern blot analysis revealed that the expression of each of the above DMAS genes is up-regulated under iron-deficient conditions in root tissue, and that of the genes OsDMAS1 and TaDMAS1 is up-regulated in shoot tissue. OsDMAS1 promoter-GUS analysis in iron-sufficient roots showed that its expression is restricted to cells participating in long distance transport and that it is highly up-regulated in the entire root under iron-deficient conditions. In shoot tissue, OsDMAS1 promoter drove expression in vascular bundles specifically under iron-deficient conditions. 相似文献
89.
Wernery U Liu C Baskar V Guerineche Z Khazanehdari KA Saleem S Kinne J Wernery R Griffin DK Chang IK 《PloS one》2010,5(12):e15824
Background
The Houbara bustard (Chlamydotis undulata) is a wild seasonal breeding bird populating arid sandy semi-desert habitats in North Africa and the Middle East. Its population has declined drastically during the last two decades and it is classified as vulnerable. Captive breeding programmes have, hitherto, been unsuccessful in reviving population numbers and thus radical technological solutions are essential for the long term survival of this species. The purpose of this study was to investigate the use of primordial germ cell-mediated chimera technology to produce viable Houbara bustard offspring.Methodology/Principal Findings
Embryonic gonadal tissue was dissected from Houbara bustard embryos at eight days post-incubation. Subsequently, Houbara tissue containing gonadal primordial germ cells (gPGCs) was injected into White Leghorn chicken (Gallus gallus domesticus) embryos, producing 83/138 surviving male chimeric embryos, of which 35 chimeric roosters reached sexual maturity after 5 months. The incorporation and differentiation of Houbara gPGCs in chimeric chicken testis were assessed by PCR with Houbara-specific primers and 31.3% (5/16) gonads collected from the injected chicken embryos showed the presence of donor Houbara cells. A total of 302 semen samples from 34 chimeric roosters were analyzed and eight were confirmed as germline chimeras. Semen samples from these eight roosters were used to artificially inseminate three female Houbara bustards. Subsequently, 45 Houbara eggs were obtained and incubated, two of which were fertile. One egg hatched as a male live born Houbara; the other was female but died before hatching. Genotyping confirmed that the male chick was a pure-line Houbara derived from a chimeric rooster.Conclusion
This study demonstrates for the first time that Houbara gPGCs can migrate, differentiate and eventually give rise to functional sperm in the chimeric chicken testis. This approach may provide a promising tool for propagation and conservation of endangered avian species that cannot breed in captivity. 相似文献90.
Amjad Hameed Muhammad Yussouf Saleem Khalid Pervaiz Akhtar Muhammad Shoaib Qumer Iqbal Muhammad Asghar 《Molecular biotechnology》2017,59(6):234-240
Tomato is one of the most consumed vegetables in the world. Diseases are the number one concern in the development of high-yield and disease-resistant tomato hybrids which is the foremost priority of breeders. Present study was conducted (1) to develop DNA-based markers for genetic confirmation of tomato F1 hybrids, (2) to utilize sequenced characterized amplified region (SCAR) marker linked to the Ph-3 gene for Phytophthora infestans resistance in tomato and (3) to evaluate male and female parental genotypes and their F1 hybrids against late blight (LB) and cucumber mosaic virus (CMV). For molecular studies, 58 previously reported markers including RAPDs (10), SCAR (01), EST-SSR (01) and SSR (46) were applied. The SCAR marker clearly differentiated the LB3 and LB4 from Roma and T-1359 and provided evidence for Ph-3 gene. The SCAR marker was able to confirm the Ph-3 gene in the hybrids Roma × LB4, Roma × LB3, Riogrande × LB2, Riogrande × LB3 and Roma × LB7. Out of several tested primers, SSR-22 proved useful for genetic confirmation of F1 hybrid TMS1 × Money Maker (MM). For LB, tested hybrids/genotypes were ranked as susceptible to highly susceptible with different infection percentage (IP). However, the pace of symptom development was slower in hybrid Rio × LB2, 45% IP after 10 days of inoculation compared with 85% disease in one of the parent genotypes (Riogrande). None of the tested genotypes was found resistant; however, TMS1 responded as tolerant against CMV using mechanical inoculation. Under natural field conditions, TMS1 was found resistant while hybrids TMS1 × Naqeeb and TMS1 × MM were tolerant where as others were found to be susceptible. In conclusion, all tomato hybrids were genetically confirmed using DNA-based markers. SCAR marker was useful for marker-assisted confirmation of the Ph-3 gene in parental lines and hybrids; however, this gene was unable to provide protection against the local population of P. infestans. 相似文献