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161.
H. Rubinsztein-Dunlop B. Littleton P. Barker P. Ljungberg Y. Malmsten 《Experiments in fluids》2001,30(1):36-42
A flow tagging technique based upon ionic fluorescence in strontium is investigated for applications to velocity measurements
in gas flows. The method is based upon a combination of two laser based spectroscopic techniques, i.e. resonantly-enhanced
ionisation and laser-induced ionic fluorescence. Strontium is first ionised and then planar laser-induced fluorescence is
utilised to give 2D `bright images' of the ionised region of the flow at a given time delay. The results show that this method
can be used for velocity measurements. The velocities were measured in two types of air–acetylene flames – a slot burner and
a circular burner yielding velocities of 5.1 ± 0.1 m/s and 9.3 ± 0.2 m/s, respectively. The feasibility of the method for
the determination of velocities in faster flows than those investigated here is discussed.
Received: 5 November 1998/Accepted: 19 January 2000 相似文献
162.
The fracture toughness of CIP-HIP Beryllium was determined using the short bar fracture toughness (KIcSB) method. The KIcSB value measured was 10.96 MPa√m at room temperature. This falls well within the expected range of 9 to 12 MPa√m as observed from previous fracture toughness measurements of beryllium. Toughness increased rapidly between 400°F and 500°F reaching a value of 16.7 MPa√m at 500°F. 相似文献
163.
The usual condition for static balance, for two bodies with masses and charges mi and ei (i = 1, 2), is . From a post-Newtonian analysis of the two-body problem, an alternate condition for static balance has been found. We do not know if this condition is exact beyond the post-Newtonian approximation. 相似文献
164.
165.
166.
B.N. Littleton A.I. Bishop T.J. McIntyre P.F. Barker H. Rubinsztein-Dunlop 《Shock Waves》2000,10(3):225-228
Abstract. A non-intrusive laser-based method for direct velocity measurements has been demonstrated in a superorbital flow facility.
The method is based upon laser enhanced ionisation velocimetry in which a tagged region is created by two step excitation
of sodium and subsequent collisional ionisation. The achieved depletion of neutral atoms is then interrogated by planar laser
induced fluorescence. The velocities were measured in the freestream at a superorbital condition yielding km/s. These results compare favourably with the measured shock speeds in the facility.
Received 15 March 1999 / Accepted 2 March 2000 相似文献
167.
This paper describes the synthesis of a range of new axially-disubstituted silicon-phthalocyanines with several ester and ether derivatives as axial ligands, including phenyl, terphenyl, thienyl and pyrenyl systems. Their absorption and emission spectra are reported and fluorescence lifetimes and quantum yields are correlated with the ligand structures. The X-ray crystal structure of a new polymorph of silicon-phthalocyanine bis(3-thienyl)acetate 7 is described. 相似文献
168.
Baldwin AJ Bader R Christodoulou J MacPhee CE Dobson CM Barker PD 《Journal of the American Chemical Society》2006,128(7):2162-2163
Protein amyloid fibrils can be functionalized by coating the core protofilament with high concentrations of proteins and enzymes. This can be done elegantly by appending a functional domain to an amyloidogenic protein monomer, then assembling the monomers into a fibril. To display an array of biologically functional porphyrins on the surface of protein fibrils, we have fused the sequence of the small, soluble cytochrome b562 to an SH3 dimer sequence that can form classical amyloid fibrils rapidly under well-defined conditions. The resulting fusion protein also forms amyloid fibrils and, in addition, binds metalloporphyrins, at half of the porphyrin binding sites as shown by UV-vis and NMR spectroscopies. Once metalloporphyrins are bound to the fibrils, the resulting holo-cytochrome domains are spectroscopically identical to the wild type cytochrome. The concentration of metalloporphyrins on a saturated fibril is estimated to be of the order of approximately 20 mM, suggesting that they could be interesting systems for applications in nanotechnology. 相似文献
169.
Lasse Murtomki Michael H. Barker Jos A. Manzanares Kysti Kontturi 《Journal of Electroanalytical Chemistry》2003,560(2):95-103
The rate of ion transfer across the supported liquid membrane (SLM) is studied in the rotating diffusion cell (RDC), varying the chemical composition of the SLM from net-cloth supported gel membranes to radiation-grafted polymer membranes. Steady-state current–voltage curves are measured as a function of the rotation rate, and values for the standard rate constant, k0, are determined for a series of tetraalkylammonium cations from the analysis of the initial slopes and the diffusion limiting currents. The analysis gives values for k0 of the order of 10−2–10−4 cm s−1, which is in rather good agreement with the values found in the literature for this type of the system. As controlled delivery of ionic drugs can be achieved by control of the electric current, whereby the SLM acts as a drug reservoir, the study is extended to the release of the anti-Alzheimer drug Tacrine, where ion-exchange fibers are embedded in the membrane as the drug carrier. Our previous transient experiments are also discussed, and it is suggested that their interpretation is seriously hampered by the non-uniform potential distribution, which brings about high capacitive currents. 相似文献
170.
We demonstrate, for the first time to our knowledge, the utility of coherent Rayleigh scattering (CRS) for temperature measurements in low-density gases and weakly ionized plasmas by measuring the translational temperature of neutral argon in a glow discharge. By analysis of the near-Gaussian spectral profile of the CRS signal, we determine temperatures with an uncertainty of =3%. We also investigate the intensity range over which this simple Gaussian analysis can be used for temperature measurements and discuss its potential for gas diagnostics. 相似文献