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221.
Kenji Uneyama 《Journal of fluorine chemistry》2008,129(7):550-576
Preparations, reactions, and synthetic applications of functionalized fluoroalkyl and alkenyl silanes have been summarized. This review focuses mainly on the chemistries of (1) 1-substituted difluoromethylsilanes (XCF2SiR3), (2) 1-substituted 2,2-difluorovinylsilanes (CF2CXSiR3), (3) trifluoroisopropenyl, trifluoroacetimidoyl, and trifluoroacetyl silanes [CF3C(SiR3)X, XCH2, NAr, O] and (4) other fluorinated alicyclic silanes. 相似文献
222.
Bin Li 《Journal of organometallic chemistry》2008,693(1):87-96
Reaction of the doubly bridged dinuclear molybdenum complex (Me2C)(Me2Si)[(η5-C5H3)Mo(CO)3]2 (1) with benzonitrile in refluxing xylene afforded complexes (Me2C)(Me2Si)[(η5-C5H3)2Mo2(CO)4(μ-η2-η2(⊥)-NCPh)] (2) (50%) and (Me2C)(Me2Si)[(η5-C5H3)2Mo2(CO)4(μ-η1-η2-NCPh)] (3) (6%) with different coordination of nitrile. The corresponding μ-η2-η2 acetonitrile and propionitrile complexes 4 and 5 could be obtained from the reactions of (Me2C)(Me2Si)(C5H4)2 with (RCN)3Mo(CO)3 (R = Me, Et) in refluxing xylene. Reactions of 1 with isonitriles generated μ-η1-η2-CNR (R = tBu, Ph, C6H11) bridged complexes 6-8 in 53-63% yields. Subsequent reaction of 4 with Ru3(CO)12 yielded two CN bond cleavaged MoRu clusters (Me2C)(Me2Si)(η5-C5H3)2Mo2Ru3(CO)10(μ-CO)(μ3-CMe)(μ4-N) (9) (7%) and [(Me2C)(Me2Si)(η5-C5H3)2]2Mo4Ru6(CO)16(μ-CO)(μ4-CO)2(μ3-η1-η2-η2-NCMe)(μ3-CMe)(μ5-N) (10) (8%). All the new complexes have been fully characterized. The molecular structures of 2, 4, 6, 9, and 10 have been determined by X-ray diffraction analysis. 相似文献
223.
In this paper, we propose a modification of Benson’s algorithm for solving multiobjective linear programmes in objective space
in order to approximate the true nondominated set. We first summarize Benson’s original algorithm and propose some small changes
to improve computational performance. We then introduce our approximation version of the algorithm, which computes an inner
and an outer approximation of the nondominated set. We prove that the inner approximation provides a set of -nondominated points. This work is motivated by an application, the beam intensity optimization problem of radiotherapy treatment
planning. This problem can be formulated as a multiobjective linear programme with three objectives. The constraint matrix
of the problem relies on the calculation of dose deposited in tissue. Since this calculation is always imprecise solving the
MOLP exactly is not necessary in practice. With our algorithm we solve the problem approximately within a specified accuracy
in objective space. We present results on four clinical cancer cases that clearly illustrate the advantages of our method. 相似文献
224.
Three papers, published coincidentally and independently by Felix Browder, Dietrich G?hde, and W. A. Kirk in 1965, triggered
a branch of mathematical research now called metric fixed point theory. This is a survey of some of the highlights of that
theory, with a special emphasis on some of the problems that remain open.
Dedicated to Felix Browder on the occasion of his 80th birthday 相似文献
225.
受听觉系统运行机制的启发,提出一种以同步性为线索的信号分量间关联度的分析方法.首先对信号进行带通滤波、逆序滤波和半波整流,继而提取一次、二次和三次极值点,并生成三种单位序列.基于单位序列分别计算相邻滤波通道同步性和一、二次极值点同步性,这两种同步性可描述信号分量间的波形吻合程度和波动关联性.分析了带有侧隙的齿轮振动信号,结果表明所提方法可发现具有较高关联性的信号分量,有助于缩减数据量和揭示被测对象的动力行为特性. 相似文献
226.
为了发挥轨道交通票价的杠杆作用,进一步完善地面公交与轨道交通衔接,优化交通结构,增加客票收入,本文通过分析国内外大都市票制体系、票价优惠策略及北京市轨道交通发展状况,提出北京市轨道交通票价改革方案。在重点分析客流量、运营成本和城市人均收入水平的基础上,确定单一票价水平为4元;实施高低峰分时定价策略,通过分析三峰时间分布及高峰客流构成,用Logit模型计算出高低峰票价分别为6元、2元;提出制定月票的策略,以及其他一系列辅助票制来保障上班族、老人等的权益。该研究为实现北京市轨道交通可持续发展提供了理论基础。 相似文献
227.
Matching for a wavefunction the WKB expansion at large distances and Taylor expansion at small distances leads to a compact, few-parametric uniform approximation found in Turbiner and Olivares-Pilon (2011). The ten low-lying eigenstates of H2+ of the quantum numbers (n,m,Λ,±) with n=m=0 at Λ=0,1,2, with n=1, m=0 and n=0, m=1 at Λ=0 of both parities are explored for all interproton distances R. For all these states this approximation provides the relative accuracy ?10−5 (not less than 5 s.d.) locally, for any real coordinate x in eigenfunctions, when for total energy E(R) it gives 10-11 s.d. for R∈[0,50] a.u. Corrections to the approximation are evaluated in the specially-designed, convergent perturbation theory. Separation constants are found with not less than 8 s.d. The oscillator strength for the electric dipole transitions E1 is calculated with not less than 6 s.d. A dramatic dip in the E1 oscillator strength f1sσg−3pσu at R∼Req is observed. The magnetic dipole and electric quadrupole transitions are calculated for the first time with not less than 6 s.d. in oscillator strength. For two lowest states (0,0,0,±) (or, equivalently, 1sσg and 2pσu states) the potential curves are checked and confirmed in the Lagrange mesh method within 12 s.d. Based on them the Energy Gap between 1sσg and 2pσu potential curves is approximated with modified Pade Re−R[Pade(8/7)](R) with not less than 4-5 figures at R∈[0,40] a.u. Sum of potential curves E1sσg+E2pσu is approximated by Pade 1/R[Pade(5/8)](R) in R∈[0,40] a.u. with not less than 3-4 figures. 相似文献
228.
Frost RL Cejka J Bostrom T Weier M Martens W 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,67(5):1220-1227
Raman spectra at 298 and 77K and infrared spectra of the uranyl sulfate mineral zippeite from Jáchymov (Joachimsthal), Czech Republic, K(0.6)(H(3)O)0.4[(UO(2))6(SO(4))3(OH)7].8H2O, were studied. Observed bands were tentatively attributed to the (UO(2))2+ and (SO(4))2- stretching and bending vibrations, the OH stretching vibrations of water molecules, hydroxyls and oxonium ions, and H(2)O, oxonium, and delta U-OH bending vibrations. Empirical relations were used for the calculation of U-O bond lengths in uranyl R (A)=f(nu(3) or nu(1)(UO(2))2+). Calculated U-O bond lengths are in agreement with U-O bond lengths from the single crystal structure analysis and those inferred for uranyl anion sheet topology of uranyl pentagonal dipyramidal coordination polyhedra. The number of observed bands supports the conclusion from single crystal structure analysis that at least two symmetrically distinct U6+ (in uranyls) and S6+ (in sulfates), water molecules and hydroxyls may be present in the crystal structure of the zippeite studied. Strong to very weak hydrogen bonds present in the crystal structure of zippeite studied were inferred from the IR spectra. 相似文献
229.
Application of interdigitated array microelectrodes as electrochemical sensors for determination of antioxidant capacity is reported. Electrochemical measurements with interdigitated electrodes (IDE) were studied in both stationary solutions and the flow system. The method is based on biamperometric measurements using ABTS+|ABTS redox couple in phosphate buffer solution, pH 7.40. During analysis, the ABTS radical cation was enzymatically produced by peroxidase in a tubular flow-through reactor. The performance of bioreactor was tested at different concentrations of immobilized enzyme, ABTS and hydrogen peroxide. The influence of flow rate on proper operation of the bioreactor was also studied. The results of antioxidant activity were determined using Trolox as a standard. The applied IDE detector accomplished good sensitivity of 0.3 nA/μM of Trolox and offered linear range between 20 to 500 μM of Trolox.The comparison of results (R2 = 0.9915) for antioxidant activity between spectroscopic and FIA biamperometric measurements by interdigitated electrodes confirmed the applicability of the proposed method for determination of antioxidant capacity. 相似文献
230.
The syntheses of organochalcogen-supported azacalix[3]arenes are described in a one-pot manner in satisfactory yields. A remarkably selective potentiometric response was accomplished for uranyl ions over a variety of other metal ions, including alkali (Na+, K+), alkaline-earth (Mg2+, Ca2+, Ba2+), transition and heavy metal ions (Co2+, Ni2+, Cu2+, Ag+, Fe3+, Zn2+, Cd2+ and Pb2+) using an ion-selective electrode based on compound 3 incorporated into a polymeric (PVC) membrane. 相似文献