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排序方式: 共有257条查询结果,搜索用时 46 毫秒
1.
Detailed flow patterns in the nasal cavity. 总被引:9,自引:0,他引:9
The human nasal cavity filters and conditions inspired air while providing olfactory function. Detailed experimental study of nasal airflow patterns has been limited because of the complex geometry of the nasal cavity. In this work, particle image velocimetry was used to determine two-dimensional instantaneous velocity vector fields in parallel planes throughout a model of the nasal cavity that was subjected to a nonoscillatory flow rate of 125 ml/s. The model, which was fabricated from 26 computed tomography scans by using rapid prototyping techniques, is a scaled replica of a human right nasal cavity. The resulting vector plots show that the flow is laminar and regions of highest velocity are in the nasal valve and in the inferior airway. The relatively low flow in the olfactory region appears to protect the olfactory bulb from particulate pollutants. Low flows were also observed in the nasal meatuses, whose primary function has been the subject of debate. Comparison of sequentially recorded data suggests a steady flow. 相似文献
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Lucyna Firlej Bogdan Kuchta Michael W. Roth Carlos Wexler 《Journal of molecular modeling》2011,17(4):811-816
The interplay between the torsional potential energy and the scaling of the 1-4 van der Waals and Coulomb interactions determines
the stiffness of flexible molecules. In this paper we demonstrate for the first time that the precise value of the nonbond
scaling factor (SF)—often a value assumed without justification—has a significant effect on the critical properties and mechanisms
of systems undergoing a phase transition, and that, for accurate simulations, this scaling factor is highly dependent on the
system under consideration. In particular, by analyzing the melting of n-alkanes (hexane C6, dodecane C12, tetracosane C24)
on graphite, we show that the SF is not constant over varying alkane chain lengths when the structural correlated transformations
are concerned. Instead, monotonic decrease of SF with the molecular length drives a cross-over between two distinct mechanisms
for melting in such systems. In a broad sense we show that the choice for SF in any simulation containing adsorbed or correlated
long molecules needs to be carefully considered. 相似文献
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Jennifer X. Qiao Sarah R. King Kan He Pancras C. Wong Alan R. Rendina Joseph M. Luettgen Baomin Xin Robert M. Knabb Ruth R. Wexler Patrick Y.S. Lam 《Bioorganic & medicinal chemistry letters》2009,19(2):462-468
We previously disclosed a series of highly potent FXa inhibitors bearing α-substituted (CH2NR1R2) phenylcyclopropyl P4 moieties in the pyrazolodihydropyridone core system. Herein, we describe our continuous SAR efforts in this series. Effects of the C-3 substitution of the pyrazolodihydropyridone core and the α-substitution (R group) of the cyclopropyl ring on FXa binding affinity (FXa Ki), human plasma anticoagulant activity (PT EC2×) and permeability are discussed. A set of compounds obtained from optimization of the R group and the C-3 substituent were orally bioavailable in dogs. Furthermore, representative compounds were highly efficacious in the rabbit arterio-venous shunt thrombosis model (EC50s = 29–81 nM). 相似文献
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Peter W. Glunz Xiaojun Zhang Yan Zou Indawati Delucca Alexandra H. Nirschl Xuhong Cheng Carolyn A. Weigelt Daniel L. Cheney Anzhi Wei Rushith Anumula Joseph M. Luettgen Alan R. Rendina Mark Harpel Gang Luo Robert Knabb Pancras C. Wong Ruth R. Wexler E. Scott Priestley 《Bioorganic & medicinal chemistry letters》2013,23(18):5244-5248
Aminoisoquinoline and isoquinoline groups have successfully replaced the more basic P1 benzamidine group of an acylsulfonamide factor VIIa inhibitor. Inhibitory activity was optimized by the identification of additional hydrophobic and hydrophilic P′ binding interactions. The molecular details of these interactions were elucidated by X-ray crystallography and molecular modeling. We also show that decreasing the basicity of the P1 group results in improved oral bioavailability in this chemotype. 相似文献
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We present results of molecular dynamics computer simulations of hexane (C6H14 or C6) and pentane (C5H12 or C5) adlayers physisorbed onto a graphite substrate, for various submonolayer coverages. The hexane and pentane molecules incorporate explicit hydrogens and the graphite is modelled as a six-layer all-atom structure. Even though C6 and C5 have different structures at monolayer completion, both systems generally behave similarly in the submonolayer regime and results are in reasonable agreement with experiment for both systems. Specifically, there are four distinct topological regimes involving empty space: at densities closest to full coverage, there are large domains with individual vacancies, then with decreasing density, large vacancy patches appear first, followed by the formation of connected networks of smaller domains with multiple orientations that ultimately separate into individual patches. The energetics and melting behaviour of all systems are readily understood within the framework of the topology presented at various densities. 相似文献
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Wenqing Yao Michael Chao Zelda R Wasserman Rui Qin Liu Maryanne B Covington Robert Newton David Christ Ruth R Wexler Carl P Decicco 《Bioorganic & medicinal chemistry letters》2002,12(1):101-104
A series of cis-1(S)2(R)-amino-2-indanol based compounds with a biphenylmethyl group at the P1' position was found to be potent aggrecanase inhibitors. Both compounds 2j and 2n possessed very high aggrecanase affinity (IC(50)=1.5nM), and showed excellent selectivity over MMP-1 and MMP-9, with moderate selectivity against MMP-2. 相似文献