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931.
Hydrogenated amorphous carbon films (a-C:H) were deposited on p-type silicon as well as silica substrates by pulsed laser deposition technique using a mixture of graphite and camphor powders. The Fourier transform infrared spectroscopy measurement revealed the presence of hydrogen in the a-C:H films. The optical properties and structure of the a-C:H film were investigated by UV-visible and Raman scattering spectroscopy. The formation of a heterojunction between the a-C:H film and silicon substrate was confirmed by the current-voltage (I-V) measurement. Furthermore, the structure of a-C:H/p-Si showed photovoltaic characteristics with an open-circuit voltage (Voc) of 0.4 V and short-circuit current density (Jsc) of about 15 mA/cm2 under AM1.5 (100 mW/cm2) illumination. From the calculation, the energy conversion efficiency and fill factor were found to be 2.1% and 0.38, respectively. The carbon layer contributed to the energy conversion efficiency, which was proved by the measurement of quantum efficiency. 相似文献
932.
Sn-Zn eutectic system is one of the most promising lead-free solders with the advantages of low melting points, excellent mechanical properties and acceptable costs, whereas its poor wetting ability confines its applications in many substrates. In this paper, gallium (Ga) was added to the Sn-Zn eutectic system in order to improve its melting properties and wetting abilities. Piecing binary phase diagram method was employed to calculate the uncharted Sn-Zn-Ga ternary phase diagram and the eutectic point of this ternary system. Differential scanning calorimeter (DSC) method was used to exam the melting point of the solder system. The SnZn6Ga solder has a melting point of 174.4 °C, with wetting rate of 48.9%, while the melting point of Sn-Zn alloy is 198.5 °C and melting rate is only about 20%. In addition, the method of piecing binary phase diagrams proves to be feasible to clarify certain unknown ternary phase systems. 相似文献
933.
《Journal of Non》2004,344(3):148-157
Enthalpy, h, and volume, v, relaxation of poly(methyl methacrylate), PMMA, and polycarbonate, PC, were measured using differential scanning calorimetry and mercury-in-glass dilatometry. For PMMA both temperature down-jumps and up-jumps were studied. Attention was paid to the influence of cooling/heating rates on aging process with the result that it is related to the corresponding shift of glass transition temperature, Tg. From the time dependence of enthalpy, h, and volume, v, the aging modulus was defined as Ka = (∂h/∂v)T, and was found to be ca. 2 GPa. This corresponds roughly to the inverse value of the compressibility, κl, in the vicinity of Tg. The results of the measurements on amorphous selenium supported the notion that Ka assumes values close to 1/κl. The measured Ka values were about 5 GPa, in fair agreement with compressibility data extracted from pvT measurements. 相似文献
934.
Transparent glasses composition of which can be expressed by the formula: (100−x) · (K2O · 2TiO2 · P2O5) · x(K2O · 2B2O3 · 7SiO2), where x=5, 10, 15 and 20 mol% (KTP-xKBS), were obtained by melt quenching technique. The structure and crystallization behavior of these glasses have been examined by Fourier transform infrared spectroscopy, differential thermal analysis and X-ray diffraction. In spite of their nominal composition, the studied glasses exhibit a similar oxygen polyhedra distribution. However, significant differences were found in the trigonal BO3 units amount. During DTA runs all the examined glasses devitrify in two steps. In the former, very small crystals of an unknown crystalline phase are produced. In KTP-5KBS and KTP-10KBS glasses anatase phase was also detected. Attempts were made in order to identify the unknown phase (UTP) for which a AB3(XO4)2(OH)6 Crandallite-type structure was proposed where the A, B and X sites were occupied by K, Ti and/or Al, and P, respectively. In the second devitrification step the crystallization of the KTiOPO4 phase occurs while the UTP phase previously formed disappears. Isothermal heat treatments performed at temperature just above Tg have allowed one to obtain transparent crystal-glass nanocomposites, formed by crystalline nanostructure of the UTP phase uniformly dispersed in the amorphous matrix. 相似文献
935.
Roos PH Venkatachalam A Manz A Waentig L Koehler CU Jakubowski N 《Analytical and bioanalytical chemistry》2008,392(6):1135-1147
Numerous structurally and enzymatically similar cytochromes P450 (CYPs) are involved in the metabolism of xenobiotics and
are present in different amounts and with different enzyme profiles in human tissues and cells. Analysis of their adaptively
regulated and individually variable patterns is a peculiar analytical challenge. We developed a laser ablation inductively
coupled plasma mass spectrometry (LA-ICP-MS) based method for concomitant detection and semiquantitative determination of
electrophoretically separated and blotted CYPs. The first results are given here for the two enzymes CYP1A1 and CYP2E1. Specific
monoclonal antibodies directed against the enzymes were differentially labelled with europium via a covalently linked chelator
and with iodine, respectively. Analysis of the modified antibodies shows that both europium and iodine are coupled to the
heavy and the light chains of the antibodies. Also, the antibodies maintained their antigen-binding properties after labelling
as demonstrated by LA-ICP-MS-analysed immunoblots. The method allowed us to detect specifically and concomitantly both CYP
enzymes in complex biological samples, i.e. microsomes of rat liver and minipig duodenum, which are characterized by different
levels and proportions of the two CYP enzymes. A strong CYP1A1 signal is found in liver microsomes of 3-methylcholanthrene-treated
rats, while it is (nearly) absent in liver microsomes of rats treated with isonocotinic acid hydrazide (isoniazid). The constitutively
expressed CYP2E1 is found in microsomes of both treatment groups. Duodenal microsomes of minipigs orally exposed to polycyclic
aromatic hydrocarbons show a clear CYP1A1 signal. Low levels of CYP2E1 can also be detected in these microsomes. The LA-ICP-MS
method allows concomitant determination of CYPs, thereby exhibiting sensitivity similar to that of conventional chemoluminescence
detection via peroxidase-labelled secondary antibodies. The latter method allows readout of a single CYP protein in a 1D separation.
Although the results presented here are only for labelling by use of the elements iodine and europium, the same strategy can
be applied also for other lanthanide elements in combination with chelating compounds, so LA-ICP-MS of western blots offers
a new capability to be applied for highly multiplexed CYP determinations via labelled antibodies. 相似文献
936.
We consider the optimization problem of minimizing in the class of functions W1,G(Ω) with , for a given φ0?0 and bounded. W1,G(Ω) is the class of weakly differentiable functions with . The conditions on the function G allow for a different behavior at 0 and at ∞. We prove that every solution u is locally Lipschitz continuous, that it is a solution to a free boundary problem and that the free boundary, Ω∩∂{u>0}, is a regular surface. Also, we introduce the notion of weak solution to the free boundary problem solved by the minimizers and prove the Lipschitz regularity of the weak solutions and the C1,α regularity of their free boundaries near “flat” free boundary points. 相似文献
937.
938.
The cytochrome P450 (P450) enzymes are mainly localized to the endoplasmic reticulum (ER), where they function within catalytic
complexes metabolizing xenobiotics and some endogenous substrates. However, certain members of families 1–3 were also found
in other subcellular compartments, such as mitochondria, plasma membrane, and lysosomes. The physiological function of these
enzymes in non-ER locations is not known, although plasma-membrane-associated P450s have been described to be catalytically
active and to participate in immune-mediated reactions with autoantibody formation that can trigger drug-induced hepatitis.
Several retention/retrieval mechanisms are active in the ER retention of the P450s and inverse integration of the translated
P450 into the ER membrane appears to be responsible for transport to the plasma membrane. Furthermore, hydrophilic motifs
in the NH2-terminal part have been suggested to be important for mitochondrial import. Phosphorylation of P450s has been described to
be important for increased rate of degradation as well as for targeting into mitochondria. It was also suggested that the
mitochondria-targeted P450s from families 1–3 could be active in drug metabolism using an alternative electron transport chain.
In this review we present an update of the field emphasizing studies concerning localization, posttranslational modification,
such as phosphorylation, and intracellular transport of microsomal P450s. 相似文献
939.
Werner Georg Nowak 《Archiv der Mathematik》2008,90(2):181-192
This article gives an asymptotic result for the lattice point discrepancy of a large body of rotation in , whose boundary is piecewise smooth and contains points of vanishing Gaussian curvature.
Received: 2 November 2006 相似文献
940.
Jesse I. Deutsch 《Archiv der Mathematik》2008,91(1):44-48
In a paper of Kim, Chan, and Rhagavan, the universal ternary classical quadratic forms over quadratic fields of positive discriminant
were discovered. Here a proof of the universality of some of these quadratic forms is given using a technique of Liouville.
Another quadratic form over the field of discriminant 8 is shown universal by a different elementary approach.
Received: 30 October 2007 相似文献