全文获取类型
收费全文 | 336篇 |
免费 | 34篇 |
专业分类
370篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 12篇 |
2020年 | 7篇 |
2019年 | 10篇 |
2018年 | 8篇 |
2017年 | 16篇 |
2016年 | 19篇 |
2015年 | 24篇 |
2014年 | 28篇 |
2013年 | 30篇 |
2012年 | 37篇 |
2011年 | 27篇 |
2010年 | 21篇 |
2009年 | 18篇 |
2008年 | 10篇 |
2007年 | 20篇 |
2006年 | 9篇 |
2005年 | 12篇 |
2004年 | 8篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 2篇 |
排序方式: 共有370条查询结果,搜索用时 15 毫秒
1.
A study was conducted on the adsorption of 45Ca2+ to a surface film of a hydrophobic protein derived from synaptic membranes isolated from bovine cerebellum. A kinetic analysis of Ca2+ displacement from the protein by various metal and organic cations could be described by a rate law based on diffusion and displacement. The relative rate constants for the displacement of bound Ca2+ were in the order Li+ <Na+, Rb+ <Cs+ <K+, NH4+. Among the alkaline earth series the sequence was Mg2+, Sr2+ <Ba2+. Ca2+ adsorption could be described by a theoretical formulation which takes into account an interfacial energy and potential barrier as well as the diffusional process. An attempt was made to consider the effect of energy of hydration of the cations, surface charge, and the chemical environment at the interface on catonic selectivity. The behavior of the cations in this system significantly resemble their behavior in natural membranes, particularly excitatory ones. The structural and physicochemical environment of the protein at the interface is discussed in relation to Ca2+ binding and cationic selectivity. 相似文献
2.
An observation of episodic feeding and growth of larval Leiostomus xanthurus in the northern Gulf of Mexico 总被引:1,自引:0,他引:1
Govoni John J.; Chester Alexander J.; Hoss Donald E.; Ortner Peter B. 《Journal of plankton research》1985,7(1):137-146
Four cruises were conducted in the northern Gulf of Mexico overtwo spawning seasons of the sciaenid fish Leiostomus xanthurus.On only one occasion did unusually high densities of larvaeand their principal microzooplanktonic foods co-occur. Peakdensities of larvae and microzooplankton were observed in athin lens of cool surface water that characterized a hydrographicdiscontinuity, and all larvae contained high numbers of foodorganisms in their guts. Instantaneous exponential growth ratesestimated from measurements of otolith growth increments, indicatedaccelerated growth on the day that larvae were collected. Alaboratory experiment verified that larval L. xanthurus respondsto an increased ration with accelerated growth that is detectableon otoliths. Together these data suggest that the spatial distributionof L. xanthurus larvae and their microzooplanktonic food ispatchy and that interactions of larvae and microzooplanktonmay be episodic. 相似文献
3.
Mareike Winchell 《The journal of the Royal Anthropological Institute》2023,29(3):611-630
Drawing from fieldwork and archival research carried out in Bolivia between 2010 and 2017, this article undertakes a rethinking of Indigenous ontologies in light of Bolivian interlocutors’ efforts to navigate deeply precarious ties to named places and saints. Attention to such instabilities challenges romantic accounts of ontology that presume a stable domain of materiality or religiosity outside of practice. During fieldwork in central Bolivia, I learned about the ways that Quechua farmers negotiated the relational and ecological effects of a divisive history of indentured labour and sexual violence through acts of devotion including paraman purina (‘walking for rain’), feasting, flute-play, dance, and chapel prayer each February for the Patron Saint La Virgen de la Candelaria, named places, and the Pachamama. These practices sought to rebuild ties to named places that were interrupted by the forbidding of offerings by the prior hacienda master and reshaped by state projects of Indigenous revivalism. These devotional practices, and participants’ narrations of them, offer insight into the political workings of Indigenous ontologies in twenty-first-century Bolivia. I propose critical ontologies as a scholarly lens that insists upon placing relations with other-than-humans within broader fields of legal and political contestation over rights, nature, and Indigeneity. 相似文献
4.
Bruce D. Davies Wayne Hoss Jan-Ping Lin Fabian Lionetti 《Molecular and cellular biochemistry》1982,44(1):23-31
Summary A noncholinergic nicotine receptor on human phagocytic leukocytes has been characterized using the binding of3H-(d,l)-nicotine. The average affinity +/-standard deviation of (d,l)-nicotine for the receptor on neutrophils is 36 ± 18 nM (n=6). The binding is saturable with an average of 8.7 x 104 sites per neutrophil. Monocytes and to a lesser extent lymphocytes but not erythrocytes also display specific binding. Bound nicotine is dissociable from the receptor and is not metabolized. Only close structural analogs of nicotine bind to the receptor, which is stereoselective for the (d)-isomer. The receptor can be occupied by (l)-nicotine at concentrations present in the blood of smokers. It is suggested that some of the adverse effects of smoking on leukocyte functions may be mediated by a specific nicotine receptor. 相似文献
5.
Meythaler M Wang Z Martinot A Pryputniewicz S Kasheta M McClure HM O'Neil SP Kaur A 《Journal of immunology (Baltimore, Md. : 1950)》2011,186(9):5151-5161
Although the cellular immune response is essential for controlling SIV replication in Asian macaques, its role in maintaining nonpathogenic SIV infection in natural hosts such as sooty mangabeys (SM) remains to be defined. We have previously shown that similar to rhesus macaques (RM), SM are able to mount a T lymphocyte response against SIV infection. To investigate early control of SIV replication in natural hosts, we performed a detailed characterization of SIV-specific cellular immunity and viral control in the first 6 mo following SIV infection in SM. Detection of the initial SIV-specific IFN-γ ELISPOT response in SIVsmE041-infected SM coincided temporally with a decline in peak plasma viremia and was similar in magnitude, specificity, and breadth to SIVsmE041-infected and SIVmac239-infected RM. Despite these similarities, SM showed a greater reduction in postpeak plasma viremia and a more rapid disappearance of productively SIV-infected cells from the lymph node compared with SIVmac239-infected RM. The early Gag-specific CD8(+) T lymphocyte response was significantly more polyfunctional in SM compared with RM, and granzyme B-positive CD8(+) T lymphocytes were present at significantly higher frequencies in SM even prior to SIV infection. These findings suggest that the early SIV-specific T cell response may be an important determinant of lymphoid tissue viral clearance and absence of lymph node immunopathology in natural hosts of SIV infection. 相似文献
6.
7.
W S Messer D O Ngur Y F Abuh L A Dokas S M Ting U Hacksell B M Nilsson P G Dunbar W Hoss 《Chirality》1992,4(8):463-468
The activities of the enantiomers of BM-5 were examined to measure muscarinic cholinergic selectivity in the central nervous system. Autoradiographic studies assessed the ability of each enantiomer to inhibit the binding of [3H]-(R)-quinuclidinyl benzilate ([3H]-(R)-QNB) to muscarinic receptors in the rat brain. (+)-(R)-BM-5 inhibited [3H]-(R)-QNB binding to rat brain sections at concentrations below 1.0 microM, while 100-fold higher concentrations of (-)-(S)-BM-5 were required for comparable levels of inhibition. Analysis of the autoradiograms indicated that both stereoisomers had a similar distribution of high affinity binding sites. Each enantiomer displayed higher affinity for muscarinic receptors in the superior colliculi and lower affinity for receptors in the cerebral cortex and hippocampus. (+)-(R)-BM-5 and oxotremorine inhibited adenylyl cyclase activity in the cerebral cortex with efficacies comparable to that for acetylcholine. (+)-(R)-BM-5 was 26-fold more potent than (-)-(S)-BM-5 in inhibiting adenylyl cyclase. Oxotremorine-M and carbamylcholine stimulated phosphoinositide turnover in the cerebral cortex. Oxotremorine had lower activity and (+)-(R)-BM-5 was essentially inactive at comparable concentrations. The difference in activity of the two enantiomers indicates a remarkable stereochemical selectivity for muscarinic receptors. The stereoselectivity index is comparable for both the autoradiographic assays (48) and measures of adenylyl cyclase activity (26) in the cerebral cortex. 相似文献
8.
Sara Montanari Munazza Saeed Mareike Kn?bel YoonKyeong Kim Michela Troggio Mickael Malnoy Riccardo Velasco Paolo Fontana KyungHo Won Charles-Eric Durel Laure Perchepied Robert Schaffer Claudia Wiedow Vincent Bus Lester Brewer Susan E. Gardiner Ross N. Crowhurst David Chagné 《PloS one》2013,8(10)
We have used new generation sequencing (NGS) technologies to identify single nucleotide polymorphism (SNP) markers from three European pear (Pyrus communis L.) cultivars and subsequently developed a subset of 1096 pear SNPs into high throughput markers by combining them with the set of 7692 apple SNPs on the IRSC apple Infinium® II 8K array. We then evaluated this apple and pear Infinium® II 9K SNP array for large-scale genotyping in pear across several species, using both pear and apple SNPs. The segregating populations employed for array validation included a segregating population of European pear (‘Old Home’בLouise Bon Jersey’) and four interspecific breeding families derived from Asian (P. pyrifolia Nakai and P. bretschneideri Rehd.) and European pear pedigrees. In total, we mapped 857 polymorphic pear markers to construct the first SNP-based genetic maps for pear, comprising 78% of the total pear SNPs included in the array. In addition, 1031 SNP markers derived from apple (13% of the total apple SNPs included in the array) were polymorphic and were mapped in one or more of the pear populations. These results are the first to demonstrate SNP transferability across the genera Malus and Pyrus. Our construction of high density SNP-based and gene-based genetic maps in pear represents an important step towards the identification of chromosomal regions associated with a range of horticultural characters, such as pest and disease resistance, orchard yield and fruit quality. 相似文献
9.
10.