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101.
Effect of Si in reactively sputtered Ti-Si-N films on structure and diffusion barrier performance 总被引:2,自引:0,他引:2
X. Sun E. Kolawa S. Im C. Garland M.-A. Nicolet 《Applied Physics A: Materials Science & Processing》1997,65(1):43-45
34 Si23N43 (b3) and Ti35Si13N52 (c3), are synthesized by reactively sputtering a Ti5Si3 or a Ti3Si target, respectively. The silicon-lean film (c3) has a columnar structure closely resembling that of TiN. As a diffusion
barrier between a shallow Si n+p junction diode and a Cu overlayer, this material is effective up to 700 °C for 30 min annealing in vacuum, a performance
similar to that for TiN. The silicon-rich (b3) film contains nanocrystals of TiN, randomly oriented and embedded in an amorphous
matrix. A film of (b3) maintains the stability of the same diode structure up to 850 °C for 30 min in vacuum. This film (b3)
is clearly superior to TiN or to (c3). Similar experiments performed with Al instead of Cu overlayers highlight the importance
of the thermodynamic stability of a barrier layer and demonstrate convincingly that for stable barriers the microstructure
is a parameter that directly determines the barrier performance.
Received: 18 November 1996/Accepted: 22 January 1997 相似文献
102.
We have evaluated thermal stability and aging property of a blue color-emitting phosphor, CaAl2Si2O8:Eu2+ (CAS:Eu2+), synthesized by conventional solid-state reaction method. When both CAS:Eu2+ and BaMgAl10O19:Eu2+ (BAM) were baked in air at 500 °C for 20 min, the decrease of photoluminescence (PL) intensity of CAS:Eu2+ was lower than that of BAM. The aging property of CAS:Eu2+ was also better than that of BAM. Due to its rigid structure and unlimited framework of silicon-oxygen and aluminum-oxygen around Eu2+ ions, Eu2+ ions were protected from outer oxidizing atmosphere and plasma discharge. After analysis of aging property and thermal stability, the differences of these thermal stability and aging property of CAS:Eu2+ from those of BAM were ascribed to its crystal structure which plays a role of a shield for Eu2+ ions against oxidation atmosphere and Xe ion bombardment. 相似文献
103.
Approximate fibrations form a useful class of maps. By definition fibrators provide instant detection of maps in this class, and PL fibrators do the same in the PL category. This paper formalizes a natural concept of partial asphericity and establishes fibrator properties of certain partially aspherical closed manifolds. One consequence is that any connected sum of aspherical PL manifolds with residually finite fundamental groups is a codimension-(2n−2) PL fibrator. 相似文献
104.
Hee-Jung Im Carl Willis Suree Saengkerdsub Rajev Makote Michelle D. Pawel Sheng Dai 《Journal of Sol-Gel Science and Technology》2004,32(1-3):117-123
Solid-state scintillating materials were synthesized by the co-doping of sol–gel components with neutron absorbers [6Li and 10B], organic fluorescence sensitizers such as salicylic acid and 2,5-diphenyloxazole (PPO) and activator 1,4-bis-2-(5-phenyloxazolyl)-benzene (POPOP). The room-temperature sol–gel process through the addition of organic polymers is the key to the successful entrapment of the organic sensitizers and activator in inorganic matrixes. These transparent or translucent sol–gel scintillators were evaluated for alpha radiation and neutron detections. 相似文献
105.
Oh C Chung SC Shin SI Kim YC Im SS Oh SG 《Journal of colloid and interface science》2002,254(1):79-86
The distribution of macropores in silica particles prepared by the hydrolysis and condensation of TEOS in a hexane/water/decyl alcohol (O(1)/W/O(2)) multiple emulsion was investigated. To stabilize the emulsion structure, hydroxypropyl cellulose (HPC) was added into the O(2) phase and polyethylene glycol (PEG) was added into the water phase. Without HPC, the particles have an irregular shape and hardly have particulate forms. As the concentration of HPC increases, the shape of particles becomes more and more spherical and the size decreases. The size of silica particles was varied from 5 to 1 microm as the concentration of HPC increased from 0.5 to 0.7 wt%. The number and size of the macropores in silica particles were affected by PEG polymer concentration. With the variation in the concentration of PEG, macropores in silica particles were located at the surface of or inside the particles. At high concentrations of PEG, the macropores in particles were located inside the particles, but at low concentrations of PEG the macropores were located at the surfaces of particles. Interestingly, the particles of dimpled surfaces were formed when the molar ratio of water to TEOS (R(w)) was 4.0 and the concentrations of PEG and HPC were 2.0 and 0.7 wt% respectively. The surface areas of dimpled silica particles and completely spherical particles, measured by the BET method, were 409 and 433 m(2)/g respectively. 相似文献
106.
Chi C Im C Enkelmann V Ziegler A Lieser G Wegner G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(23):6833-6845
Oligofluorenes (a trimer, pentamer, and heptamer) with one fluorenone unit in the center (OFnK: n=3, 5, or 7) were synthesized and used as models to understand the origin of the low-energy emission band in the photoluminescence and electroluminescence spectra of some polyfluorenes. All compounds form glasses with T(g) at 30 degrees C (OF3 K), 50 degrees C (OF5 K) and 57 degrees C (OF7 K). Oligomers OF5 K and OF7 K exhibit smectic liquid crystal phases that undergo transition to isotropic melts at 107 and 205 degrees C, respectively. Oligomer OF5 K could be obtained in form of single crystals. The X-ray structure analysis revealed the helical nature of the molecule and a helix reversal defect located at the central fluorenone unit. The packing pattern precludes formation of excimers. Electrochemical properties were investigated by cyclic voltammetry. The ionization potential (I(p)) and electron affinity (E(a)) were calculated from these data. Studies of the photophysical properties of OFnK in solution and thin film by steady-state and time-resolved fluorescence spectroscopic measurements suggest efficient funneling of excitation energy from the photoexcited fluorene segments to the low-energy fluorenone sites by both intra- and intermolecular hopping events whereby they give rise to green emission. Intermolecular energy transfer was investigated by using a model system composed of a highly defect free polyfluorene PF2/6 doped by OFnK. F?rster-type energy transfer takes place from PF2/6 to OFnK. The energy-transfer efficiency increases predictably with increasing concentration of OFnK. 相似文献
107.
Lee HY Kang HK Jo EJ Kim JI Lee YN Lee SH Park YM Ryu SH Kwak JY Bae YS 《Experimental & molecular medicine》2004,36(2):135-144
Dendritic cells (DCs) play a key role in activating the immune response against invading pathogens as well as dying cells or tumors. Although the immune response can be initiated by the phagocytic activity by DCs, the molecular mechanism involved in this process has not been fully investigated. Trp-Lys-Tyr-Met-Val-Met-NH(2) (WKYMVM) stimulates the activation of phospholipase D (PLD) via Ca(2+) increase and protein kinase C activation in mouse DC cell line, DC2.4. WKYMVM stimulates the phagocytic activity, which is inhibited in the presence of N-butanol but not t-butanol in DC2.4 cells. Furthermore, the addition of phosphatidic acid, an enzymatic product of PLD activity, enhanced the phagocytic activity in DC2.4 cells. Since at least two of formyl peptide receptor (FPR) family (FPR1 and FPR2) are expressed in DC2.4 as well as in mouse bone marrow-derived dendritic cells, this study suggests that the activation of FPR family by WKYMVM stimulates the PLD activity resulting in phagocytic activity in DC2.4 cells. 相似文献
108.
A synthetic absorbable bicomponent monofilament suture (MonoFlex), composed of poly(p-dioxanone) and its copolymer, was prepared by a conjugate spinning method, and its degradation behavior was investigated in vitro and in vivo. MonoFlex degraded by hydrolysis, and retained approximately 55% of its original strength after four weeks of incubation in PBS at 37 °C. About 70% of the original strength was maintained after four weeks of implantation in rats, and the suture material was completely absorbed after 180-210 days post-implantation in rats. No remarkable tissue reactions were observed during degradation, and foreign body reactions were similar to those of commercially available suture materials composed of poly(p-dioxanone). This study to monitor the degradation behavior of monofilament sutures in vitro as well as in vivo may be useful in the development of novel suture materials for extended wound support. 相似文献
109.
Wang W Li F Hong J Lee CO Cho HY Im KS Jung JH 《Chemical & pharmaceutical bulletin》2003,51(4):435-439
Four new saponins, designated as certonardosides K-N (1-3, 5), were isolated, along with culcitoside C(6) (4), from the brine shrimp active fraction of the starfish Certonardoa semiregularis. The structures were determined on the basis of spectral analysis and chemical derivatization. These compounds were evaluated for cytotoxicity and antibacterial activity. 相似文献
110.
Fernández P Durand JS Pérez-Conde C Paniagua G 《Analytical and bioanalytical chemistry》2003,375(8):1020-1023
This paper reports a new flow-through fluoroimmunosensor, the function of which is based on antibodies immobilized on an inmunoreactor of controlled-pore glass (CPG), for determination of digoxin, used in the treatment of congestive heart failure and artery disease. The immunosensor has a detection limit of 1.20 microg L(-1) and provides high reproducibility (RSD=4.5% for a concentration of 0.0025 mg L(-1), and RSD=6.7% for 0.01 mg L(-1)). The optimum working concentration range was found to be 1.2 x 10(-3)-4.0 x 10(-2) mg L(-1). The lifetime of the immunosensor was about 50 immunoassays; if stored unused its lifetime can be extended to three months. A sample speed of about 10-12 samples per hour can be attained. Possible interference from substances with structures similar to digoxin (morphine, heroin, tebaine, codeine, pentazocine and narcotine) was investigated. No cross-reactivity was seen at the highest digoxin: interferent ratio studied (1:100). The proposed fluoroimmunosensor was successfully used to determine digoxin concentrations in human serum samples. 相似文献