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1.
- 1.
- 1. The plasma membrane has been isolated from rat myometrium using a single step density gradient centrifugation without any salt extraction. A new kind of continuous sucrose density gradient was prepared using an Instrumentation Specialities Co. (ISCO) density gradient former. Other subcellular fractions were also obtained by this technique. 相似文献
2.
Escherichia coli and Bacillus megaterium rendered permeable to ribonucleoside triphosphates by toluene treatment retain the capacity to synthesize discrete ribonucleic acid species. 相似文献
3.
Stimulation of tissue plasminogen activator by denatured proteins and fibrin clots: A possible additional role for plasminogen activator? 总被引:1,自引:0,他引:1
Purified plasminogen activator from pig heart displays weak activity toward plasminogen, with or without detergents present. The activation rate is enhanced at least 50 times upon addition of low concentrations (1 μg/ml) of many proteins following their denaturation by acid, base, or heat. No native proteins, at concentrations up to 10 mg/ ml, enhanced plasminogen activator activity. The degree of enhancement by many denatured proteins was as great as that caused by the presence of a fibrin clot, and occurred at lower protein concentrations. Similar observations with activators from human vena cava and cadaver perfusate suggest that the effect is probably general to tissue activators. None of the denatured proteins examined enhanced the activity of urokinase, streptokinase, staphylokinase, or plasmin. Small proteins known to renature rapidly, such as RNAse, and highly ordered structural proteins, such as collagen and keratin, could not be converted to stimulators of plasminogen activators by treatment with acid or base. If, as appears likely, plasminogen activator can indeed recognize and be stimulated by misfolded proteins, a possible role in selective catabolism of damaged protein in general, not solely fibrin clots, is evident. If the nature of the stimulatory peptide grouping can be elucidated, plasminogen activator may also be a valuable tool both for study of protein denaturation and clarification of the clot stimulatory effect in fibrinolysis. 相似文献
4.
Radcliffe CE Drucker DB Boote V Fletcher-Williams G Claydon MA 《Canadian journal of microbiology》2001,47(1):96-101
Species of Peptostreptococcus cause a variety of infections, primarily abscesses of soft tissues, joints, and mucous membranes. The aim of this study was to compare the phospholipid analogue profiles of Peptostreptococcus species, represented by P. anaerobius, P. asaccharolyticus, P. indolicus, P. lacrimalis, and P. prevotii; Micromonas micros (P. micros) and Finegoldia magna (P. magnus). After anaerobic growth on blood-FAA, lipids extracted by chloroform-methanol (2:1 v/v) were purified, then analysed by fast atom bombardment mass spectrometry (FAB-MS) in negative ion mode. The major peaks with mass to charge (m/z) 719, 721, and 749, corresponded to phosphatidylglycerol analogues, namely PG (32:1), PG (32:0), and PG (34:0), which have been found previously in Lactobacillus spp., Clostridium difficile, and Staphylococcus spp. Other major peaks observed, with m/z 619, 647, 665, 675, 677, 687, 691, 693, 701, 703, 707, 733, and 746 have also been reported in one or more of these three species. However, other major peaks found here in Peptostreptococcus, Micromonas, and Finegoldia have not been described elsewhere; these are 501, 514, 515, 618, 659, 673, 676, 688, 690, 692, 694, 700, 706, 715, 718, 722, and 750. We conclude that Peptostreptococcus, Micromonas, and Finegoldia isolates are chemically unique. 相似文献
5.
In multi-cellular organisms, failure to properly regulate cell-cycle progression can result in inappropriate cell death or uncontrolled cell division leading to tumor formation. To guard against such events, conserved regulatory mechanisms called "checkpoints" block progression into mitosis in response to DNA damage and incomplete replication, as well as in response to other signals. Checkpoint mutants in organisms as diverse as yeast and humans are sensitive to various chemical agents that inhibit DNA replication or cause DNA damage. This phenomenon is the primary rationale for chemotherapy, which uses drugs that preferentially target tumor cells with compromised checkpoints. In this study, we demonstrate the use of Drosophila checkpoint mutants as a system for assaying the effects of various DNA-damaging and anti-cancer agents in a developing multicellular organism. Dwee1, grp and mei-41 are genes that encode kinases that function in the DNA replication checkpoint. We tested zygotic mutants of each gene for sensitivity to the DNA replication inhibitor hydroxyurea (HU), methyl methanosulfonate (MMS), ara-C, cisplatin, and the oxygen radical generating compound paraquat. The mutants show distinct differences in their sensitivity to each of the drugs tested, suggesting an underlying complexity in the responses of individual checkpoint genes to genotoxic stress. 相似文献
6.
The proper folding of tubulins and their incorporation into microtubules consist of a series of reactions, in which evolutionarily conserved proteins, cofactors A to E, play a vital role. We have cloned a fission yeast gene (alp41(+)) which encodes a highly conserved small GTP-binding protein homologous to budding yeast CIN4 and human ARF-like Arl2. alp41(+) is essential, disruption of which results in microtubule dysfunction and growth polarity defects. Genetic analysis indicates that Alp41 plays a crucial role in the cofactor-dependent pathway, in which it functions upstream of the cofactor D homologue Alp1(D) and possibly in concert with Alp21(E). 相似文献
7.
The proper folding of tubulins prior to their incorporation into microtubules requires a group of conserved proteins called
cofactors A to E. In fission yeast, homologues of these cofactors (at least B, D and E) are necessary for the biogenesis of
microtubules and for cell viability. Here we show that the temperature-sensitive alp11-924 mutant, which is defective in the cofactor B homologue, contains an opal nonsense mutation, which results in the production
of a truncated Alp11B protein (Alp111–118). We isolated a tRNATrp gene as a multicopy suppressor of this mutation, which rescues alp11-924 by read-through of the nonsense codon. The truncated Alp111–118 protein lacks the C-terminal half of Alp11B, consisting of a central coiled-coil region and the distal CLIP-170 domain found in a number of proteins involved in microtubule
functions. Both of these domains are required for the maintenance of microtubule architecture in vivo. Detailed functional
analyses lead us to propose that Alp11B comprises three functional domains: the N-terminal half executes the essential function, the central coiled-coil region is
necessary for satisfactory maintenance of cellular α-tubulin levels, and the C-terminal CLIP-170 domain is required for efficient
binding to α-tubulin.
Received: 29 November 1999 / Accepted: 18 April 2000 相似文献
8.
Applications of supercritical fluid extraction and chromatography in forensic science 总被引:2,自引:0,他引:2
Radcliffe C Maguire K Lockwood B 《Journal of biochemical and biophysical methods》2000,43(1-3):261-272
Supercritical fluid technology is a rapidly expanding analytical technique. Here we give a brief insight into the background of supercritical fluid technology and how supercritical fluid extraction and supercritical fluid chromatography work in analysis. The applications of these two techniques in forensic science are known to be important. The main area of forensic use of supercritical fluid technology is in the sample preparation and separation of drugs of abuse particularly opiates, cannabinoids, cocaine and sedatives. Supercritical fluid technology can be used for both time-of-death-related drug analysis and for obtaining information relating to long term drug abuse. We also give a review of the use of supercritical fluids in two other major forensic areas, fingerprinting and the extraction and separation of explosives from both bombing events and gunshot residues. Overall we show that supercritical fluid technology is fast becoming a major part of forensic investigations and that it is an invaluable analysis technique. 相似文献
9.
Webber D Radcliffe CM Royle L Tobiasen G Merry AH Rodgers AL Sturrock ED Wormald MR Harvey DJ Dwek RA Rudd PM 《The FEBS journal》2006,273(13):3024-3037
Urinary glycoproteins are important inhibitors of calcium oxalate crystallization and adhesion of crystals to renal cells, both of which are key mechanisms in kidney stone formation. This has been attributed to glycosylation of the proteins. In South Africa, the black population rarely form stones (incidence < 1%) compared with the white population (incidence 12-15%). A previous study involving urinary prothrombin fragment 1 from both populations demonstrated superior inhibitory activity associated with the protein from the black group. In the present study, we compared N-linked and O-linked oligosaccharides released from urinary prothrombin fragment 1 isolated from the urine of healthy and stone-forming subjects in both populations to elucidate the relationship between glycosylation and calcium oxalate stone pathogenesis. The O-glycans of both control groups and the N-glycans of the black control samples were significantly more sialylated than those of the white stone-formers. This demonstrates a possible association between low-percentage sialylation and kidney stone disease and provides a potential diagnostic method for a predisposition to kidney stones that could lead to the implementation of a preventative regimen. These results indicate that sialylated glycoforms of urinary prothrombin fragment 1 afford protection against calcium oxalate stone formation, possibly by coating the surface of calcium oxalate crystals. This provides a rationale for the established roles of urinary prothrombin fragment 1, namely reducing the potential for crystal aggregation and inhibiting crystal-cell adhesion by masking the interaction of the calcium ions on the crystal surface with the renal cell surface along the nephron. 相似文献
10.