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901.
Anatoly F. Nastoyashchiy 《Journal of Russian Laser Research》2011,32(3):238-246
We propose a simple target in the form of a miniature torus, in which the heavy shell is used to confine the plasma spread,
for a solution of the laser-fusion problem. We achieve a significant decrease of heat losses using an external magnetic field
and/or as a result of a self-sustaining magnetic field that is generated in the plasma. We formulate the conditions and determine
the energy of the laser pulse (or of a beam of fast charged particles) required to ignite a thermonuclear DD reaction and
obtain a positive energy yield. We show that the stopping range of α-particles does not exceed the small radius of the torus
within a broad range of the plasma and magnetic-field parameters. 相似文献
902.
Delevoye L Trébosc J Gan Z Montagne L Amoureux JP 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2007,186(1):94-99
A new decoupling composite pulse sequence is proposed to remove the broadening on spin S=1/2 magic-angle spinning (MAS) spectra arising from the scalar coupling with a quadrupolar nucleus I. It is illustrated on the (31)P spectrum of an aluminophosphate, AlPO(4)-14, which is broadened by the presence of (27)Al/(31)P scalar couplings. The multiple-pulse (MP) sequence has the advantage over the continuous wave (CW) irradiation to efficiently annul the scalar dephasing without reintroducing the dipolar interaction. The MP decoupling sequence is first described in a rotor-synchronised version (RS-MP) where one parameter only needs to be adjusted. It clearly avoids the dipolar recoupling in order to achieve a better resolution than using the CW sequence. In a second improved version, the MP sequence is experimentally studied in the vicinity of the perfect rotor-synchronised conditions. The linewidth at half maximum (FWHM) of 65 Hz using (27)Al CW decoupling decreases to 48 Hz with RS-MP decoupling and to 30 Hz with rotor-asynchronised MP (RA-MP) decoupling. The main phenomena are explained using both experimental results and numerical simulations. 相似文献
903.
Eric Weise 《Czechoslovak Journal of Physics》2005,55(1):A27-A34
COMPASS is a fixed target experiment at CERN studying nucleon spin structure in polarised deep inelastic muon nucleon scattering and hadron spectroscopy using hadron beams. The main goal of the COMPASS spin physics program is the measurement of the helicity contribution of the gluons to the nucleon spin, ΔG. This quantity is accessible via the photon-gluon-fusion process which can be selected by open charm production or production of hadron pairs with large transverse momenta. The spin physics program of COMPASS includes also measurements with a transversely polarised target. These allow to measure the transverse structure function.COMPASS has up to now successfully finished three runs with a muon beam of 160 GeV and a longitudinally polarized6LiD target in the years 2002, 2003 and 2004. An overview of the physics addressed by the muon program, with an emphasis on the ΔG/G measurement will be presented. The status of the analysis of the highpt hadron pairs, open charm, longitudinal and transverse asymmetries will be reviewed. 相似文献
904.
Lin Wang Heqing Yang Hua Zhao Ru Yu Shi Liu Bao Bin Liu 《Applied Physics A: Materials Science & Processing》2011,102(1):61-68
The present work reports on novel four-layer thermally driven piezoresistive cantilevers implemented in one- and two-dimensional
arrays for parallel proximity scanning. There, the heater (metallic meander), the piezoresistive deflection sensor, and the
metal actuation film with significantly higher thermal expansion coefficient make up separate layers. Actuation efficiency
and cross-talk of the novel cantilever design are studied and compared with two recent designs: thin metallic film and ion-implanted
heater. The novel actuator, integrated on a 240 μm long and 3 μm thick silicon cantilever and supplied by V
dc=1 V enables deflections up to 5 μm of the AFM-tip with an actuation efficiency of about 170 nm/mW and suppressed cross-talk
between actuator and sensor. 相似文献
905.
Nanoflakes-built pyrite FeS2 microspheres were synthesized through a simple solvothermal process in mixed solvents of N, N-dimethytformamide and ethylene
glycol without using any surfactant. Both the composition of the solvents and urea were key factors for the formation of the
uniform products. It was found that the flake-like intermediate products transformed into FeS2 nanoflakes in situ in the early stage and Ostwald ripening growth mechanism would contribute to the uniformity of the final
products. Electrochemical studies revealed that the nanoflakes-built pyrite FeS2 microspheres exhibited large lithium storage capacities. This method can be easily controlled and is expected to be extendable
to the fabrication of other metal chalcogenides with controlled shape and structure. 相似文献
906.
M. A. Kudryashov A. I. Mashin A. S. Tyurin A. E. Fedosov G. Chidichimo G. De Filpo 《Technical Physics》2011,56(1):92-96
Silver/polyacrylonitrile (Ag/PAN) nanocomposites are synthesized at the stage of simultaneous acrylonitrile polymerization
and the reduction of silver ions from a mixture of silver nitrate AgNO3, acrylonitrile, and a photoinitiator. The synthesized films are transparent in the visible region and are characterized by
a uniform dispersion of silver nanoparticles in a PAN matrix without any macroscopic agglomeration. The effects of the metal
salt and photoinitiator concentrations on the size and density of metal nanoparticles in a composite are revealed. 相似文献
907.
908.
909.
Robbin S. Johnson 《Journal of nanoparticle research》2011,13(4):1467-1476
This article uses lessons from biotechnology to help inform the design of oversight for nanobiotechnology. Those lessons suggest
the following: first, oversight needs to be broadly defined, encompassing not just regulatory findings around safety and efficacy,
but also public understanding and acceptance of the technology and its products. Second, the intensity of scrutiny and review
should reflect not just risks but also perceptions of risk. Finally, a global marketplace argues for uniform standards or
commercially practical solutions to differences in standards. One way of designing oversight to achieve these purposes is
to think about it in three phases—precaution, prudence, and promotion. Precaution comes early in the technology or product’s
development and reflects real and perceived uncertainties. Prudence governs when risks and hazards have been identified, containment
approaches established, and benefits broadly defined. Transparency and public participation rise to the fore. The promotional
phase moves toward shaping public understanding and acceptance and involves marketing issues rather than safety ones. This
flexible, three-phase approach to oversight would have avoided some of the early regulatory problems with agricultural biotechnology.
It also would have led to a more risk-adjusted pathway to regulatory approval. Furthermore, it would avoid some of the arbitrary,
disruptive marketing issues that have arisen. 相似文献
910.
Ran Li Ming-Fan Li Ji-Rong Ren 《The European Physical Journal C - Particles and Fields》2011,71(2):1566
We extend the recently proposal of hidden conformal symmetry to the self-dual warped AdS3 black holes in topological massive gravity. It is shown that the wave equation of massive scalar field with sufficient small
angular momentum can be reproduced by the SL(2, R) Casimir quadratic operator. Due to the periodic identification in the φ direction, it is found that only the left section of hidden conformal symmetry is broken to U(1), while the right section
is unbroken, which only gives the left temperature of dual CFT. As a check of the dual CFT conjecture of self-warped AdS3 black hole, we further compute the Bekenstein–Hawking entropy and absorption cross section and quasinormal modes of scalar
field perturbation and show these are just of the forms predicted by the dual CFT. 相似文献