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91.
Formation of Na nanotubes inside the channels of anodic aluminium oxide (AAO) membranes has been achieved by decomposing NaH thermally on AAO. The as-produced material, Na@AAO, is applied as a reactive template to prepare other tubular materials. Reacting Na@AAO with gaseous C6Cl6 generates carbon nanotubes (ca. 250 nm, wall thickness of 20 nm, tube length of 60 microm) inside the AAO channels. Highly aligned bundles of nearly amorphous carbon nanotubes are isolated after AAO is removed. 相似文献
92.
Wiskur SL Lavigne JJ Ait-Haddou H Lynch V Chiu YH Canary JW Anslyn EV 《Organic letters》2001,3(9):1311-1314
[structure in text] The pK(a) values and the geometries of secondary and tertiary amines adjacent to boronic acids were determined using potentiometric and (11)B NMR titrations. The studies showed that the secondary ammonium ion has a pK(a) similar to that of the tertiary ammonium species, which leads to the formation of tetrahedral boron centers at pH values above approximately 5.5. Therefore, secondary amines as well as tertiary amines, when placed proximal to boron centers, can be used to create tetrahedral boronic acids at neutral pH for diol complexation. 相似文献
93.
Laser-scanning angular deviation microscopy based on the small angle measurement using surface plasmon resonance (SPR) phase
detection technique is proposed. The phase shift coming from a SPR sensor is measured by a common-path heterodyne interferometry.
This phase deviation is proportional to the beam converging or diverging angle, due to the specimen departing from the focal
plane of objective lens. Using the phase deviations, one can calculate the surface profile by use of numerical method. The
specimen could be scanned in real-time and the axial-resolution could be better than 1 nm.
PACS 07.79-v; 68.37.-d; 73.20.Mf; 42.30.Wb; 42.62.Eh 相似文献
94.
W.Y. Zhang C.H. Chiu L.C. Zhang K. Biswas H. Ehrenberg W.C. Chang J. Eckert 《Journal of magnetism and magnetic materials》2007
The effect of refractory element addition on phase transformation, crystallization behavior and magnetic properties of Pr8.5Fe81.5B10 (addition-free) and Pr8.5Fe81.5M2B10 (M=V, Cr, Nb, Zr, Ti) ribbons has been investigated. The annealed addition-free ribbon as well as the samples with V or Cr additions are mainly composed of the metastable Pr2Fe23B3 phase, whereas annealed ribbons with Nb, Zr or Ti additions primarily consist of Pr2Fe14B and a minor amount of Fe3B/boride. The complete suppression of the metastable Pr2Fe23B3 phase due to Nb, Zr or Ti additions leads to a significant enhancement of the magnetic properties. For example, the remanence, the coercivity and the energy product are remarkably increased from 2.5 kG, 0.4 kOe and 0.2 MG Oe for the addition-free material to 9.2 kG, 4.7 kOe and 7.6 MG Oe for the specimens with Nb addition. The successful elimination of the metastable Pr2Fe23B3 phase is believed to profit from two factors: (a) Nb, Zr or Ti atoms substitute the Pr site, comparatively increase the Pr content, and thus inhibit the nucleation of Pr-lean Pr2Fe23B3 phases, and (b) the formation of Nb, Zr, or Ti borides consumes some part of B, which hinders the generation of the B-rich Pr2Fe23B3 phase. 相似文献
95.
We have reported that photodynamic therapy (PDT) using the photosensitizer phthalocyanine (Pc) 4 and red light damages the antiapoptotic protein Bcl-2. Recently, using transient transfection of Bcl-2 deletion mutants, we identified the membrane anchorage domains of Bcl-2 as necessary to form the photosensitive target. However, it is not clear how Bcl-2 photodamage sensitizes cells to Pc 4-PDT-induced apoptosis, whether overall cell killing is also sensitized or how up-regulation of Bcl-2 in tumors might make them more or less responsive to Pc 4-PDT. In this study we report on MCF-7c3 cells (human breast cancer cells expressing stably transfected procaspase-3) overexpressing wild-type Bcl-2 or certain deletion mutants in either a transient or a stable mode. By flow cytometric analysis of transiently transfected cells, we found that wild-type Bcl-2, Bcl-2delta33-54 and Bcl-2delta37-63 (each of which can be photodamaged) protected cells from apoptosis caused by Pc 4-PDT. In contrast, Bcl-2delta210-239, which lacks the C-terminal transmembrane domain and cannot be photodamaged, afforded no protection. We then evaluated the PDT sensitivity of transfected cell lines stably overexpressing high levels of wild-type Bcl-2 or one of the Bcl-2 mutants. Overexpression of wild-type Bcl-2, Bcl-2delta33-54 or Bcl-2delta37-63 resulted in relative resistance of cells to Pc 4-PDT, as assessed by morphological apoptosis or loss of clonogenicity. Furthermore, overexpression of Bcl-2 also inhibited the activation-associated conformational change of the proapoptotic protein Bax, and higher doses of Pc 4 and light were required to activate Bax in cells expressing high levels of Bcl-2. Many advanced cancer cells have elevated amounts of Bcl-2. Our results show that increasing the dose of Pc 4-PDT can overcome the resistance afforded by either Bcl-2 or the two mutants. PDT regimens that photodamage Bcl-2 lead to activation of Bax, induction of apoptosis and elimination of the otherwise resistant tumor cells. 相似文献
96.
97.
98.
A study of a bluff-body combustor using laser sheet lighting 总被引:2,自引:0,他引:2
Laser sheet lighting is used to study reacting flows with and without heat release in an axisymmetric, unducted and vertically mounted bluff-body combustor. The fuel, which is seeded with titanium tetrachloride vapor, is ejected from a jet located in the center of the bluff-body. The TiCl4 in the dry fuel reacts spontaneously with the water in the annulus air to form titanium dioxide particles. High speed movies and visual observations of vertically and horizontally located sheets of laser light provided remarkably detailed visualization (via Mie scattering) of the vortex dynamics in the near-wake region of the bluff-body.A version of this paper was presented at the ASME Winter Annual Meeting of 1984 and printed in AMD, Vol. 66 相似文献
99.
Using 1 MHz pulse-echo ultrasound externally applied to detect mastoid effusion: cadaver experiments
The objective of this study is to explore the feasibility of using ultrasound to detect mastoid effusion (ME). In the past, ultrasound has been used to measure middle ear effusion (MEE) by injecting water into the external ear canal to measure echoes from the tympanic membrane, which is uncomfortable for the patient. It has been shown that air cells in the mastoid of patients with MEE are filled with fluid, which implies that ME could be a useful indicator of MEE. This study suggests using ultrasound to detect ME as a potentially noninvasive approach for MEE detection. In vitro experiments were performed on ten cadaver samples of the human ear. A single-element 1 MHz transducer was used to measure the mastoid of each cadaver before and after injecting water into the mastoid. The experimental results showed that the relative amplitudes of ultrasonic signals differed significantly between before (0.24 ± 0.09, mean ± standard deviation) and after (0.15 ± 0.03) the water injection (p < 0.05, t-test), demonstrating that the ultrasonic reflection can be used to detect ME. The location of the human mastoid under the skin behind the ear allows external measurements, and hence ultrasound-based ME detection may be an alternative, noninvasive diagnostic approach to detecting MEE in the future, providing an examination that avoids discomfort. 相似文献
100.
Adare A Afanasiev S Aidala C Ajitanand NN Akiba Y Al-Bataineh H Alexander J Al-Jamel A Aoki K Aphecetche L Armendariz R Aronson SH Asai J Atomssa ET Averbeck R Awes TC Azmoun B Babintsev V Baksay G Baksay L Baldisseri A Barish KN Barnes PD Bassalleck B Bathe S Batsouli S Baublis V Bauer F Bazilevsky A Belikov S Bennett R Berdnikov Y Bickley AA Bjorndal MT Boissevain JG Borel H Boyle K Brooks ML Brown DS Bucher D Buesching H Bumazhnov V Bunce G Burward-Hoy JM Butsyk S Campbell S Chai JS Chang BS 《Physical review letters》2007,98(16):162301
Differential measurements of elliptic flow (v2) for Au+Au and Cu+Cu collisions at sqrt[sNN]=200 GeV are used to test and validate predictions from perfect fluid hydrodynamics for scaling of v2 with eccentricity, system size, and transverse kinetic energy (KE T). For KE T identical with mT-m up to approximately 1 GeV the scaling is compatible with hydrodynamic expansion of a thermalized fluid. For large values of KE T mesons and baryons scale separately. Quark number scaling reveals a universal scaling of v2 for both mesons and baryons over the full KE T range for Au+Au. For Au+Au and Cu+Cu the scaling is more pronounced in terms of KE T, rather than transverse momentum. 相似文献