全文获取类型
收费全文 | 392篇 |
免费 | 14篇 |
专业分类
化学 | 295篇 |
晶体学 | 1篇 |
力学 | 27篇 |
数学 | 46篇 |
物理学 | 37篇 |
出版年
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 4篇 |
2019年 | 11篇 |
2018年 | 9篇 |
2017年 | 3篇 |
2016年 | 15篇 |
2015年 | 4篇 |
2014年 | 9篇 |
2013年 | 17篇 |
2012年 | 16篇 |
2011年 | 26篇 |
2010年 | 17篇 |
2009年 | 20篇 |
2008年 | 26篇 |
2007年 | 24篇 |
2006年 | 17篇 |
2005年 | 17篇 |
2004年 | 18篇 |
2003年 | 17篇 |
2002年 | 10篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 9篇 |
1973年 | 2篇 |
1970年 | 1篇 |
1967年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有406条查询结果,搜索用时 46 毫秒
141.
Non‐Porous Iron(II)‐Based Sensor: Crystallographic Insights into a Cycle of Colorful Guest‐Induced Topotactic Transformations 下载免费PDF全文
Santiago Rodríguez‐Jiménez Dr. Humphrey L. C. Feltham Prof. Sally Brooker 《Angewandte Chemie (International ed. in English)》2016,55(48):15067-15071
Materials capable of sensing volatile guests at room temperature by an easily monitored set of outputs are of great appeal for development as chemical sensors of small volatile organics and toxic gases. Herein the dinuclear iron(II) complex, [FeII2( L )2(CH3CN)4](BF4)4?2 CH3CN ( 1 ) [ L =4‐(4‐methylphenyl)‐3‐(3‐pyridazinyl)‐5‐pyridyl‐4H‐1,2,4‐triazole], is shown to undergo reversible single‐crystal‐to‐single‐crystal (SCSC) transformations upon exposure to vapors of different guests: 1 (MeCN)? 2 (EtOH)→ 3 (H2O)? 1 (MeCN). Whilst 1 and 2 remain dimetallic, SCSC to 3 involves conversion to a 1D polymeric chain (due to a change in L bridging mode), which, remarkably, can undergo SCSC de‐polymerization, reforming dimetallic 1 . Additionally, SC‐XRD studies of two ordered transient forms, 1TF3 and 2TF3 , confirm that guest exchange occurs by diffusion of the new guests into the non‐porous lattices as the old guests leave. These reversible SCSC events also induce color and magnetic responses. Indeed dark red 1 is spin crossover active (T1/2↓ 356 K; T1/2↑ 369 K), whilst orange 2 and yellow 3 remain high spin. 相似文献
142.
Michel R Subramaniam V McArthur SL Bondurant B D'Ambruoso GD Hall HK Brown MF Ross EE Saavedra SS Castner DG 《Langmuir : the ACS journal of surfaces and colloids》2008,24(9):4901-4906
Planar supported lipid bilayers that are stable under ambient atmospheric and ultra-high-vacuum conditions were prepared by cross-linking polymerization of bis-sorbylphosphatidylcholine (bis-SorbPC). X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were employed to investigate bilayers that were cross-linked using either redox-initiated radical polymerization or ultraviolet photopolymerization. The redox method yields a more structurally intact bilayer; however, the UV method is more compatible with incorporation of transmembrane proteins. UV polymerization was therefore used to prepare cross-linked bilayers with incorporated bovine rhodopsin, a light-activated, G-protein-coupled receptor (GPCR). A previous study (Subramaniam, V.; Alves, I. D.; Salgado, G. F. J.; Lau, P. W.; Wysocki, R. J.; Salamon, Z.; Tollin, G.; Hruby, V. J.; Brown, M. F.; Saavedra, S. S. J. Am. Chem. Soc. 2005, 127, 5320-5321) showed that rhodopsin retains photoactivity after incorporation into UV-polymerized bis-SorbPC, but did not address how the protein is associated with the bilayer. In this study, we show that rhodopsin is retained in supported bilayers of poly(bis-SorbPC) under ultra-high-vacuum conditions, on the basis of the increase in the XPS nitrogen concentration and the presence of characteristic amino acid peaks in the ToF-SIMS data. Angle-resolved XPS data show that the protein is inserted into the bilayer, rather than adsorbed on the bilayer surface. This is the first study to demonstrate the use of ultra-high-vacuum techniques for structural studies of supported proteolipid bilayers. 相似文献
143.
Mansell D Rattray N Etchells LL Schwalbe CH Blake AJ Bichenkova EV Bryce RA Barker CJ Díaz A Kremer C Freeman S 《Chemical communications (Cambridge, England)》2008,(41):5161-5163
Natural myo-inositol phosphate antioxidants containing the 1,2,3-trisphosphate motif bind Fe(3+) in the unstable penta-axial conformation. 相似文献
144.
Rapid on-chip multi-step (bio)chemical procedures in continuous flow--manoeuvring particles through co-laminar reagent streams 总被引:1,自引:0,他引:1
We introduce a novel and extremely versatile microfluidic platform in which tedious multi-step biochemical processes can be performed in continuous flow within a fraction of the time required for conventional methods. 相似文献
145.
Influences of coadsorbed sodium and water, aqueous solvent, and electrode potential on the kinetics of O(2) dissociation over Pt(111) are systematically investigated using density functional theory models of vacuum and electrochemical interfaces. Na coadsorption alters the electronic states of Pt to stabilize the reactant (O(2)*), transition, and product (2O*) states by facilitating electron donation to oxygen, causing a more exothermic reaction energy (-0.84 eV for Na and O(2), -0.81 eV for isolated O(2)) and a decrease in dissociation barrier (0.39 eV for Na and O(2), 0.57 eV for isolated O(2)). Solvation decreases the reaction energy (-0.67 eV) due to enhanced hydrogen bond stabilization of O(2)* compared to 2O*. The influence of Na is less pronounced at the solvated interface (barrier decreases by only 0.11 eV) because H(2)O screens Na charge-donation. In the electrochemical model system, the dissociation energy becomes more exothermic and the barrier decreases toward more positive potentials. Potential-dependent behavior results from changes in interfacial dipole moment and polarizability between O(2)*, the dissociation transition state, and 2O*; each are influenced by changes in adsorption and hydrogen bonding. Coadsorption of Na in the solvated system dampens the dipole moment change between O(2)* and 2O* and significantly increases the polarizability at the dissociation transition state and for 2O*; the combination causes little change in the reaction energy but reduces the activation barrier by 0.08 eV at 0 V versus NHE. The potential-dependent behavior contrasts that determined at a constant surface charge or from an applied electric field, illustrating the importance of considering the electrochemical potential at the fully-solvated interface in determining reaction energetics, even for non-redox reactions. 相似文献
146.
Candace M. Day Martin J. Sweetman Shane M. Hickey Yunmei Song Yongjun Liu Na Zhang Sally E. Plush Sanjay Garg 《Molecules (Basel, Switzerland)》2021,26(1)
Conventional chemotherapies used for breast cancer (BC) treatment are non-selective, attacking both healthy and cancerous cells. Therefore, new technologies that enhance drug efficacy and ameliorate the off-target toxic effects exhibited by currently used anticancer drugs are urgently needed. Here we report the design and synthesis of novel mesoporous silica nanoparticles (MSNs) equipped with the hormonal drug tamoxifen (TAM) to facilitate guidance towards estrogen receptors (ERs) which are upregulated in breast tumours. TAM is linked to the MSNs using a poly-ʟ-histidine (PLH) polymer as a pH-sensitive gatekeeper, to ensure efficient delivery of encapsulated materials within the pores. XRD, HR-TEM, DLS, SEM, FT-IR and BET techniques were used to confirm the successful fabrication of MSNs. The MSNs have a high surface area (>1000 m2/g); and a mean particle size of 150 nm, which is an appropriate size to allow the penetration of premature blood vessels surrounding breast tumours. Successful surface functionalization was supported by FT-IR, XPS and TGA techniques, with a grafting ratio of approximately 29%. The outcomes of this preliminary work could be used as practical building blocks towards future formulations. 相似文献
147.
Agarwal Umesh P. Ralph Sally A. Baez Carlos Reiner Richard S. 《Cellulose (London, England)》2021,28(14):9069-9079
Cellulose - In cellulose materials, the cellulose II allomorph is often present either exclusively or in conjunction with cellulose I, the natural cellulose. Moreover, in regenerated and mercerized... 相似文献
148.
The design, synthesis, and characterization of a novel dinuclear Eu(III) bismacrocyclic conjugate 1.Eu2 as a delayed luminescent lanthanide sensor for dicarboxylates is discussed. The sensor was shown to bind small dicarboxylic acids such as aspartic, malonic, succinic, or glutaric acid in pH 6.5 solutions. However, only malonic acid gave rise to selective Eu(III) luminescent enhancements, as the emission was reduced for all of the other acids. 相似文献
149.
Natarajan A Du W Xiong CY DeNardo GL DeNardo SJ Gervay-Hague J 《Chemical communications (Cambridge, England)》2007,(7):695-697
Heterofunctional azide and alkyne PEG-linkers have been synthesized and site specifically conjugated to scFv via a reactive thiol functionality; two scFv were coupled by copper catalyzed 1,3-dipolar cycloaddition to make divalent scFv (di-scFv) with an inter-scFv distance defined to provide divalent binding; antigen binding was maintained for the di-scFv construct and increased several times compared to that of the parent scFv; the cycloaddition reaction reported herein represents an important ligation strategy to covalently link macromolecular proteins and retain sensitive structural conformations. 相似文献
150.
Dmitriy Silin Liviu Tomutsa Sally M. Benson Tad W. Patzek 《Transport in Porous Media》2011,86(2):495-515
Synchrotron-based X-ray microtomography (micro CT) at the Advanced Light Source (ALS) line 8.3.2 at the Lawrence Berkeley
National Laboratory produces three-dimensional micron-scale-resolution digital images of the pore space of the reservoir rock
along with the spacial distribution of the fluids. Pore-scale visualization of carbon dioxide flooding experiments performed
at a reservoir pressure demonstrates that the injected gas fills some pores and pore clusters, and entirely bypasses the others.
Using 3D digital images of the pore space as input data, the method of maximal inscribed spheres (MIS) predicts two-phase
fluid distribution in capillary equilibrium. Verification against the tomography images shows a good agreement between the
computed fluid distribution in the pores and the experimental data. The model-predicted capillary pressure curves and tomography-based
porosimetry distributions compared favorably with the mercury injection data. Thus, micro CT in combination with modeling
based on the MIS is a viable approach to study the pore-scale mechanisms of CO2 injection into an aquifer, as well as more general multi-phase flows. 相似文献