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911.
Dr. Safak Bulut Dr. Philipp Eiden Witali Beichel Dr. John M. Slattery Dr. Tom F. Beyersdorff Dr. Thomas J. S. Schubert Prof. Dr. Ingo Krossing 《Chemphyschem》2011,12(12):2296-2310
A series of bis(trifluoromethylsulfonyl)imide ionic liquids (ILs) with classical as well as mildly functionalized cations was prepared and their viscosities and conductivities were determined as a function of the temperature. Both were analyzed with respect to Arrhenius, Litovitz and Vogel–Fulcher–Tammann (VFT) behaviors, as well as in the context of their molecular volume (Vm). Their viscosity and conductivity are highly correlated with Vm/T or related expressions (R2≥0.94). With the knowledge of Vm of new cations, these correlations allow the temperature‐dependent prediction of the viscosity and conductivity of hitherto unknown, non‐ or mildly functionalized ILs with low error bars (0.05 and 0.04 log units, respectively). The influence of the cation structure and mild functionalization on the physical properties was studied with systematically altered cations, in which Vm remained similar. The To parameter obtained from the VFT fits was compared to the experimental glass temperature (Tg) and the Tg/To ratio for each IL was calculated using both experimental values and Angell’s relationship. With Walden plots we investigated the IL ionicity and interpreted it in relation to the cation effects on the physical IL properties. We checked the validity of these Vm/T relations by also including the recently published variable temperature viscosity and conductivity data of the [Al(ORF)4]? ILs with RF=C(H)(CF3)2 (error bars for the prediction: 0.09 and 0.10 log units, respectively). 相似文献
912.
Takezawa Y Böckmann P Sugi N Wang Z Abe S Murakami T Hikage T Erker G Watanabe Y Kitagawa S Ueno T 《Dalton transactions (Cambridge, England : 2003)》2011,40(10):2190-2195
Spherical protein cages such as an iron storage protein, ferritin, have great potential as nanometer-scale capsules to assemble and store metal ions and complexes. We report herein the synthesis of a composite of an apo-ferritin cage and Ru(p-cymene) complexes. Ru complexes were efficiently incorporated into the ferritin cavity without degradation of its cage structure. X-Ray crystallography revealed that the Ru complexes were immobilized on the interior surface of the cage mainly by the coordination of histidine residues. 相似文献
913.
Philipp AA Meyer MR Wissenbach DK Weber AA Zoerntlein SW Zweipfenning PG Maurer HH 《Analytical and bioanalytical chemistry》2011,400(1):127-135
The Thai medicinal plant Mitragyna speciosa (kratom) is misused as a herbal drug. Besides this, a new herbal blend has appeared on the drugs of abuse market, named Krypton,
a mixture of O-demethyltramadol (ODT) and kratom. Therefore, urine drug screenings should include ODT and focus on the metabolites of the kratom alkaloids mitragynine (MG), paynantheine (PAY), speciogynine (SG), and speciociliatine (SC). The aim of this study was to
develop a full-scan gas chromatography–mass spectrometry procedure for monitoring kratom or Krypton intake in urine after enzymatic cleavage of conjugates, solid-phase extraction, and trimethylsilylation. With
use of reconstructed mass chromatography with the ions m/z 271, 286, 329, 344, 470, 526, 528, and 586, the presence of MG, 16-carboxy-MG, 9-O-demethyl-MG, and/or 9-O-demethyl-16-carboxy-MG could be indicated, and in case of Krypton, with m/z 58, 84, 116, 142, 303, 361, 393, and 451, the additional presence of ODT and its nor metabolite could be indicated. Compounds
were identified by comparison with their respective reference spectra. Depending on the plant type, dose, administration route,
and/or sampling time, further metabolites of MG, PAY, SG, and SC could be detected. The limits of detection (signal-to-noise
ratio of 3) were 100 ng/ml for the parent alkaloids and 50 ng/ml for ODT. As mainly metabolites of the kratom alkaloids were detected in urine, the detectability of kratom was tested successfully using rat urine after administration of a common user’s dose of MG. As the metabolism in humans was
similar, this procedure should be suitable to prove an intake of kratom or Krypton. 相似文献
914.
In experiments using hot wires near the wall, it is well known that wall interference effects between the hot wire and the
wall give rise to errors, and mean velocity data from the viscous sublayer can usually not be used to determine the wall position,
nor the friction velocity from the linear velocity distribution. Here, we introduce a new method that takes advantage of the
similarity of the probability density distributions (PDF) or rather the cumulative distribution functions (CDF) in the near-wall
region. By using the velocity data in the CDF in a novel way, it is possible to circumvent the problem associated with heat
transfer to the wall and to accurately determine both the wall position and the friction velocity. Prior to its exploitation,
the self-similarity of the distribution functions of the streamwise velocity fluctuations within the viscous sublayer is established,
and it is shown that they can accurately be described by a lognormal distribution. 相似文献
915.
Large Scale Accumulation Patterns of Inertial Particles in Wall-Bounded Turbulent Flow 总被引:1,自引:0,他引:1
Gaetano Sardina Francesco Picano Philipp Schlatter Luca Brandt Carlo Massimo Casciola 《Flow, Turbulence and Combustion》2011,86(3-4):519-532
Turbulent internal flow in channel and pipe geometry with a diluted second phase of inertial particles is studied numerically. Direct numerical simulations (DNS) are performed at moderate Reynolds number (Re ?? ????200) in pipe and two channels??a smaller one similar in size to previous studies and a 3?×?3-times larger one??and Eulerian statistics pertaining to the particle concentration are evaluated. This simulation box constitutes the largest domain used for particle-laden flows so far. The resulting two-point correlations of the particle concentration show that in the smaller channel the particles organize in thin, streamwise elongated patterns which are very regular and long. The spanwise spacing of these structures is 120 and 160 plus units for the channel and pipe, respectively. Only in the larger box, the streamwise extent is long enough for the particle streaks to decorrelate, thus allowing the particles to move more freely. The influence of the box size on the characteristics of the turbophoresis is clearly shown; a 10% increase of the near-wall correlation is observed for particles with Stokes number St ?+??=?50. It is thus shown that the box dimensions are an important factor in correctly assessing the motion of inertial particles, and their relation to the underlying velocity field. In addition the binning size effects on the correlation statistics of particle concentration are exploited. In particular the spanwise correlation peak values appear very sensitive to the adopted binning size, although the position of these peaks is found almost independent. Hence to allow a significant comparison between data of different configurations it is necessary to adopt the same binning spacing in inner variable. 相似文献
916.
We extend the program potfit, which generates effective atomic interaction potentials from ab initio data, to electrostatic interactions and induced dipoles. The potential parametrization algorithm uses the Wolf direct, pairwise summation method with spherical truncation. The polarizability of oxygen atoms is modeled with the Tangney-Scandolo interatomic force field approach. Due to the Wolf summation, the computational effort in simulation scales linearly in the number of particles, despite the presence of electrostatic interactions. Thus, this model allows to perform large-scale molecular dynamics simulations of metal oxides with realistic potentials. Details of the implementation are given, and the generation of potentials for SiO(2) and MgO is demonstrated. The approach is validated by simulations of microstructural, thermodynamic, and vibrational properties of liquid silica and magnesia. 相似文献
917.
We present a method for the rapid and direct determination of dissolved Thallium (Tl) using high resolution sector field inductively coupled mass spectrometry (SF-ICP-MS) suitable for the measurement of large time series (e.g. during monitoring). Thallium data are presented for a series of natural sea water samples, which were validated with sea water standards CASS-4 and NASS-5. The sea water samples and standards were diluted 10 times prior to measurement with SF-ICP-MS in low resolution mode (R = 300, LR). For both CASS-4 and NASS-5 (salinity of 30.5) we calculated a concentration of about 11 ng L−1 when using Tl values of 14 ± 2 ng L−1 (at salinity of 35 ± 1) published by Flegal and Patterson [1] for Atlantic and Pacific sea water. For CASS-4 we report a Tl value of 10.6 ± 0.7 ng L−1 (n = 70), for NASS-5 a Tl value of 10.3 ± 0.8 ng L−1 (n = 11). For Tl in both CASS-4 and NASS-5, the overall error in accuracy and precision is less than 4% and 8% (2 s), respectively. Further, values of 7.7 ± 0.3 and 6.7 ± 0.2 ng L−1 Tl were found for the estuarine standard SLEW-3 (salinity of 15) and the river water standard SLRS-4, respectively, for which no certified value exists so far. The detection and quantification limits of our method are 0.1 and 0.3 ng L−1, respectively. Slight differences in the accuracy of our method and other published methods for the determination of Tl in sea water are discussed. Time-series of natural coastal water samples gave Tl values (6-12 ng L−1), which correspond to determined salinities, and hence, appear realistic and oceanographically consistent. 相似文献
918.
The chain type nitridotantalate LiSr2[TaN3]F was synthesized by reaction of strontium with AlF3, Eu(NH2)2, LiN3 and lithium metal as fluxing agent in weld shut tantalum ampoules. Single crystals were obtained as byproduct from reaction with the ampoule material. The crystal structure (Pbca (no. 61), a = 10.768(2), b = 5.5913(11), c = 15.891(3) Å, Z = 8) was solved on the basis of single‐crystal X‐ray diffraction data. LiSr2[TaN3]F contains infinite chains of vertex sharing TaN4 tetrahedra running along [010]. The structure can be understood as an intercalation of Li+ and F– into Sr2TaN3. Lattice energy calculations (MAPLE) and EDX measurements confirmed the electrostatic bonding interactions and the chemical composition. 相似文献
919.
It is commonly believed that, whenever timescale separation holds, the predictions of reduced chemical master equations obtained using the stochastic quasi-steady-state approximation are in very good agreement with the predictions of the full master equations. We use the linear noise approximation to obtain a simple formula for the relative error between the predictions of the two master equations for the Michaelis-Menten reaction with substrate input. The reduced approach is predicted to overestimate the variance of the substrate concentration fluctuations by as much as 30%. The theoretical results are validated by stochastic simulations using experimental parameter values for enzymes involved in proteolysis, gluconeogenesis, and fermentation. 相似文献
920.
Philipp Mücke Ruth Edge Sébastien Clément Stanislav Záliš Rainer F. Winter 《Journal of organometallic chemistry》2011,696(20):3186-3197
Pseudo-para[2.2]paracyclophane- and [2.1]orthocyclophane-bridged diruthenium complexes 2 and 3 with two interlinked electroactive styryl ruthenium moieties have been prepared and investigated. Both complexes undergo two reversible consecutive one-electron oxidation processes which are separated by 270 or 105 mV. Stepwise electrolysis of the neutral complexes to first the mixed-valent radical cations and then the dioxidized dications under IR monitoring reveal incremental shifts of the charge-sensitive Ru(CO) bands and allow for an assignment of their radical cations as moderately or very weakly coupled mixed-valent systems of class II according to Robin and Day. Ground-state delocalization in the mixed-valent forms of these complexes as based on the CO band shifts is considerably larger for the “closed” paracyclophane as for the “half-open” orthocyclophane. Experimental findings are backed by the calculated IR band patterns and spin density distributions for radical cations of slightly simplified model complexes 2Me+ and 3Me+ with the PiPr3 ligands replaced by PMe3. Radical cations 2+ and 3+ feature a characteristic NIR band that is neither present in their neutral or fully oxidized forms nor in the radical cation of the monoruthenium [2.2]paracyclophane complex 1 with just one vinyl ruthenium moiety. These bands are thus assigned as intervalence charge-transfer (IVCT) transitions. Our results indicate that, for the radical cations, electronic coupling “through-space” via the stacked styrene decks is significantly more efficient than the “through-bond” pathway. 相似文献