全文获取类型
收费全文 | 251篇 |
免费 | 12篇 |
出版年
2021年 | 1篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 10篇 |
2015年 | 15篇 |
2014年 | 9篇 |
2013年 | 12篇 |
2012年 | 12篇 |
2011年 | 25篇 |
2010年 | 11篇 |
2009年 | 7篇 |
2008年 | 5篇 |
2007年 | 5篇 |
2006年 | 8篇 |
2005年 | 7篇 |
2004年 | 7篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 14篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 8篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 8篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1967年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有263条查询结果,搜索用时 406 毫秒
1.
D Poland 《Biopolymers》1999,50(7):720-732
A statistical mechanical model is given for linear associating systems that contain defects, using the double-stranded actin polymer as an example. We treat the system as a one-dimensional lattice that can desorb monomers (giving defects) using grand partition function techniques. The main difference from a standard adsorption problem is that the monomer units are also responsible for the structural integrity of the lattice (polymer) and if too many desorb the polymer will be broken. We use literature data to estimate the density of defects in the actin polymer. 相似文献
2.
D Poland 《Biophysical chemistry》2001,94(3):185-199
In the present paper we show how one can use the perturbation of some molecular optical property (for example circular dichroism or chemical shift) as a function of concentration to construct cluster distribution functions describing the self-association of molecules in solution. The optical data are first converted into data giving the variation of the average extent of clustering as a function of the total concentration and then, using straightforward thermodynamics, a set of moments of the cluster distribution function can be obtained. Utilizing the maximum-entropy method, the moments are then used to calculate approximate distribution functions, where the more moments that are used the better the approximation obtained. Given the probability distribution for clusters of different sizes one can then calculate the equilibrium constant for each stage of association. Thus one converts average degree of association into equilibrium constants without having to use any specific model. By this method one can clearly tell whether the equilibrium constants remain constant, increase, or decrease with the number of molecules in a cluster. We apply the method to literature data for two systems, namely daunorubicin, which has a strong tendency to cluster in solution, and Mg(ATP)(2-) which forms weaker clusters. We find that the successive equilibrium constants for adding a monomer to a cluster are approximately constant for daunorubicin but clearly decrease as a function of increasing cluster size for Mg(ATP)(2-). 相似文献
3.
Thomas M. Becker Jack D. Poland Thomas J. Quan Mark E. White Jonathan M. Mann Allan M. Barnes 《The Western journal of medicine》1987,147(5):554-557
Meningitis caused by Yersinia pestis developed in 6 (6%) of a total of 105 patients with plague reported to the Centers for Disease Control from 1970 to 1979. Five of the six cases occurred in children aged 10 to 15 years. All six patients received antibiotic therapy before meningitis developed, which appeared between the 9th and 14th days after the onset of acute illness in five of the six patients. There were no neurologic sequelae. The antigenic and biochemical profiles of the Y pestis strains isolated from cerebrospinal fluid in the meningitis cases did not differ from those of the Y pestis strains obtained from blood and bubo aspirates in the other 99 patients, and neither did in vitro studies suggest antibiotic resistance. While plague meningitis is an uncommon complication of acute plague infection, physicians in the western United States should be aware that it may develop as much as 14 days after antibiotic therapy for the acute plague infection has been initiated. 相似文献
4.
Photoaffinity labeling of the Ah receptor 总被引:6,自引:0,他引:6
A series of halodibenzo-p-dioxins with the photolabile aryl azide functional group were synthesized and screened as potential photoaffinity labels for the Ah receptor, and 2-azido-3-iodo-7,8-dibromodibenzo-p-dioxin was selected for radiosynthesis with 125I (specific activity 2176 Ci/mmol, equilibrium dissociation constant, KD = 0.76 nM). Following incubation of this 125I-labeled photoaffinity ligand with the protamine sulfate-precipitated fraction of C57BL/6J mouse liver cytosol, and irradiation with long wavelength ultraviolet light, the radiolabeled macromolecules were precipitated with acetone and analyzed by denaturing gel electrophoresis and autoradiography. Among the labeled products, two peptides with apparent molecular masses of 95,000 and 70,000 daltons had the following properties: 1) they were selectively labeled at low ligand concentrations; 2) they were labeled in approximately a 1:1 ratio; 3) co-incubation with receptor agonists inhibited the photoaffinity labeling of both peptides to a similar extent, and structure activity relationship for inhibition of labeling by these agonists corresponded to that for their binding affinity to the Ah receptor; 4) upon nondenaturing chromatographic separation of photoaffinity labeled cytosol on high performance liquid chromatography size exclusion and anion exchange columns, the 95- and 70-kDa peptides coelute; 5) the migration of these peptides upon denaturing electrophoresis is the same in the presence or absence of a thiol reducing agent; and 6) proteolysis of the 95- and 70-kDa peptides produces a similar pattern of cleavage peptides. The simplest structure of the Ah receptor in mouse liver cytosol, appears to be a dimer composed of two noncovalently linked subunits of apparent molecular masses of 95 and 70 kDa, which have homologous structure and similar ligand binding sites, but other possibilities are discussed. 相似文献
5.
Multiple opiate receptor agonists and antagonists have been found to produce different patterns of anterior pituitary hormone release. The present studies examined the pattern of anterior pituitary hormone release produced by buprenorphine. The effects of the kappa agonist ethylketocyclazocine on thyroid stimulating hormone release were also examined. Following buprenorphine, serum levels of corticosterone and luteinizing hormone were not changed while growth hormone release was stimulated in a dose-dependent manner. Prolactin release was stimulated after the lowest dose of buprenorphine while the highest dose induced a fall in serum prolactin. Similar biphasic effects on thyroid stimulating hormone were seen after either buprenorphine or ethylketocyclazocine. The results provide support for the role of multiple opiate receptors in opiate-induced changes in anterior pituitary hormone release. 相似文献
6.
Edward J. B. Beeley P. A. Bennett L. G. I. Poland J. S. 《Biological trace element research》1990,(1):53-61
A microcomputer-controlled irradiation and measurement system and a microprocessor-controlled sample changer have been installed
at the SLOWPOKE-2 Facility at the Royal Military College of Canada (RMC). These systems can provide the gamut of instrumental
neutron activation analysis (INAA) techniques for the analyst. Custom software has been created for system control, data acquisition,
and off-line spectral analysis using programs that incorporate Gaussian peak-fitting methods of analysis. The design and use
of the equipment is discussed, and the performance is illustrated with results obtained from the analysis of marine sediment
and biological reference materials. 相似文献
7.
The effects of the trichothecene mycotoxins (acetyl T-2 toxin, T-2 toxin, HT-2 toxin, palmityl T-2 toxin, diacetoxyscirpenol (DAS), deoxynivalenol (DON), and T-2 tetraol) on bovine platelet function were examined in homologous plasma stimulated with platelet activating factor (PAF). The mycotoxins inhibited platelet function with the following order of potency: acetyl T-2 toxin > palmityl T-2 toxin = DAS > HT-2 toxin = T-2 toxin. While T-2 tetraol was completely ineffective as an inhibitor, DON exhibited minimal inhibitory activity at concentrations above 10×10?4M. The stability of the platelet aggregates formed was significantly reduced in all mycotoxin treated platelets compared to that of the untreated PAF controls. It is suggested that the increased sensitivity of PAF stimulated bovine platelets to the more lipophilic mycotoxins may be related to their more efficient partitioning into the platelet membrane compared to the more hydrophilic compounds. 相似文献
8.
Although several studies have demonstrated the efficacy of the vasopressin analog DDAVP in enhancing human memory, no previous study has reported the dose-response relationship of DDAVP to memory in healthy young adults. The present study was undertaken to explore the dose-response curve for DDAVP on recall of implicational sentences. Five doses of DDAVP (0, 5, 15, 30, and 60 micrograms) were administered intranasally to healthy young adult male volunteers. Results demonstrated a facilitation in cued recall after treatment with the 60-micrograms dose and a general impairment in recall after treatment with the 15-micrograms dose. These effects were independent of subject's weight, vocabulary ability, and concentration of salivary cortisol. 相似文献
9.
本文首先根据眼小叶蝉族Alebrini讨论翅的命名,接着是眼小叶蝉属Alebra Fieb.和东半球眼小叶蝉族各属的评论。Homa elongata Kato移入属AsialebraDwor.,Shaddai distanti Dwor.是S.typicus Dist.的异名。描述了6个新种,即Sobralacapreola,S.clara,Orientalebra drawidana,Afralebra melichari,A.youngi,A.paolii. 本文引言部分讨论小叶蝉亚科Typhlocybinae翅的形态学,正文为分类部分。 在描述内部构造以及端节、头、和胸部背面时,使用习惯术语。 新种模式标本系列保存于下列博物馆中;正模的保管者在有关描述中最先提到: SMTD——德国得累斯顿,国家动物学博物馆。 BMNH——英国伦敦,英国自然历史博物馆。 USNM——美国华盛顿,美国国家博物馆。 MM——捷克斯洛伐克Brno,Moravian博物馆。 相似文献
10.
Eric L. Olson Matthew N. Rouse Michael O. Pumphrey Robert L. Bowden Bikram S. Gill Jesse A. Poland 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2013,126(5):1179-1188
Wheat production is currently threatened by widely virulent races of the wheat stem rust fungus, Puccinia graminis f. sp. tritici, that are part of the TTKSK (also known as ‘Ug99’) race group. The diploid D genome donor species Aegilops tauschii (2n = 2x = 14, DD) is a readily accessible source of resistance to TTKSK and its derivatives that can be transferred to hexaploid wheat, Triticum aestivum (2n = 6x = 42, AABBDD). To expedite transfer of TTKSK resistance from Ae. tauschii, a direct hybridization approach was undertaken that integrates gene transfer, mapping, and introgression into one process. Direct crossing of Ae. tauschii accessions with an elite wheat breeding line combines the steps of gene transfer and introgression while development of mapping populations during gene transfer enables the identification of closely linked markers. Direct crosses were made using TTKSK-resistant Ae. tauschii accessions TA1662 and PI 603225 as males and a stem rust-susceptible T. aestivum breeding line, KS05HW14, as a female. Embryo rescue enabled recovery of F1 (ABDD) plants that were backcrossed as females to the hexaploid recurrent parent. Stem rust-resistant BC1F1 plants from each Ae. tauschii donor source were used as males to generate BC2F1 mapping populations. Bulked segregant analysis of BC2F1 genotypes was performed using 70 SSR loci distributed across the D genome. Using this approach, stem rust resistance genes from both accessions were located on chromosome arm 1DS and mapped using SSR and EST-STS markers. An allelism test indicated the stem rust resistance gene transferred from PI 603225 is Sr33. Race specificity suggests the stem rust resistance gene transferred from TA1662 is unique and this gene has been temporarily designated SrTA1662. Stem rust resistance genes derived from TA1662 and PI 603225 have been made available with selectable molecular markers in genetic backgrounds suitable for stem rust resistance breeding. 相似文献