全文获取类型
收费全文 | 356篇 |
免费 | 13篇 |
国内免费 | 6篇 |
专业分类
化学 | 194篇 |
晶体学 | 1篇 |
力学 | 6篇 |
数学 | 72篇 |
物理学 | 102篇 |
出版年
2023年 | 5篇 |
2022年 | 6篇 |
2021年 | 8篇 |
2020年 | 3篇 |
2019年 | 11篇 |
2018年 | 3篇 |
2017年 | 7篇 |
2016年 | 11篇 |
2015年 | 9篇 |
2014年 | 10篇 |
2013年 | 22篇 |
2012年 | 28篇 |
2011年 | 14篇 |
2010年 | 11篇 |
2009年 | 16篇 |
2008年 | 24篇 |
2007年 | 12篇 |
2006年 | 17篇 |
2005年 | 17篇 |
2004年 | 14篇 |
2003年 | 9篇 |
2002年 | 13篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 12篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有375条查询结果,搜索用时 15 毫秒
91.
Aaij R Abellan Beteta C Adeva B Adinolfi M Adrover C Affolder A Ajaltouni Z Albrecht J Alessio F Alexander M Alkhazov G Alvarez Cartelle P Alves AA Amato S Amhis Y Anderson J Appleby RB Aquines Gutierrez O Archilli F Arrabito L Artamonov A Artuso M Aslanides E Auriemma G Bachmann S Back JJ Bailey DS Balagura V Baldini W Barlow RJ Barschel C Barsuk S Barter W Bates A Bauer C Bauer T Bay A Bediaga I Belogurov S Belous K Belyaev I Ben-Haim E Benayoun M Bencivenni G Benson S Benton J Bernet R 《Physical review letters》2012,108(10):101803
We present a measurement of the time-dependent CP-violating asymmetry in B(s)(0) → J/ψ? decays, using data collected with the LHCb detector at the LHC. The decay time distribution of B(s)(0) → J/ψ? is characterized by the decay widths Γ(H) and Γ(L) of the heavy and light mass eigenstates, respectively, of the B(s)(0) - B(s)(0) system and by a CP-violating phase ?(s). In a sample of about 8500 B(s)(0) → J/ψ? events isolated from 0.37 fb(-1) of pp collisions at sqrt[s] = 7 TeV, we measure ?(s) = 0.15 ± 0.18(stat) ± 0.06(syst) rad. We also find an average B(s)(0) decay width Γ(s) ≡ (Γ(L) + Γ(H))/2 = 0.657 ± 0.009(stat) ± 0.008(syst) ps(-1) and a decay width difference ΔΓ(s) ≡ Γ(L) - Γ(H) = 0.123 ± 0.029(stat) ± 0.011(syst) ps(-1). Our measurement is insensitive to the transformation (?(s),ΔΓ(s)) ? (π - ?(s), -ΔΓ(s)). 相似文献
92.
E. Butler G. B. Andresen M. D. Ashkezari M. Baquero-Ruiz W. Bertsche P. D. Bowe C. L. Cesar S. Chapman M. Charlton A. Deller S. Eriksson J. Fajans T. Friesen M. C. Fujiwara D. R. Gill A. Gutierrez J. S. Hangst W. N. Hardy M. E. Hayden A. J. Humphries R. Hydomako M. J. Jenkins S. Jonsell L. V. J?rgensen S. L. Kemp L. Kurchaninov N. Madsen S. Menary P. Nolan K. Olchanski A. Olin A. Povilus P. Pusa C. ?. Rasmussen F. Robicheaux E. Sarid S. Seif el Nasr D. M. Silveira C. So J. W. Storey R. I. Thompson D. P. van der Werf J. S. Wurtele Y. Yamazaki 《Hyperfine Interactions》2012,212(1-3):15-29
93.
94.
A. Chubykalo A. Espinoza R. Alvarado Flores A. Gutierrez Rodriguez 《Foundations of Physics Letters》2006,19(1):37-49
In this work we substantiate the applying of the Helmholtz vector decomposition theorem (H-theorem) to vector fields in classical
electrodynamics. Using the H-theorem, within the framework of the two-parameter Lorentz-like gauge (so called v-gauge), we show that two kinds of magnetic vector potentials exist: one of them (solenoidal) can act exclusively with the velocity
of light c and the other one (irrotational) with an arbitrary finite velocity v (including a velocity more than c). We show also that the irrotational component of the electric field has a physical meaning and can propagate exclusively
instantaneously. 相似文献
95.
Q. Xiong G. Chen H.R. Gutierrez P.C. Eklund 《Applied Physics A: Materials Science & Processing》2006,85(3):299-305
Results from Raman scattering experiments on individual crystalline GaP nanowires are presented which indicate that the shape of the nanowire, i.e., the high aspect ratio, may be responsible for two new phenomena involving optical phonons: (1) a shape-inducedsplitting of both the longitudinal optical (LO) and transverse optical (TO) phonons at the center of the Brillouin zone (q=0), and (2) a Raman scattering “antenna” effect which masks the normal Raman polarization selection rules. We suggest that (1) stems from the asymmetry in the long range dipolar sums that control the electromagnetic LO-TOsplitting, and we identify the Raman antenna effect (2) with the internal electric field created by Mie resonances in the nanowire driven by the incident laser field. Although these effects are reported here for GaP, they are expected to be general effects observable in many semiconducting nanowire systems. PACS 78.67.-n; 78.67.Lt; 78.30.-j; 78.30.Fs; 72.10.Di 相似文献
96.
Araujo K Colina M Mazurek R Delgado J Ledo H Gutierrez E Herrera L 《Analytical and bioanalytical chemistry》1996,355(3-4):319-320
The mercury concentrations in wastewater and sewage sludge of a stabilization pond system have been evaluated. The system is built by three parallel facultative ponds followed by two systems of three maturation ponds in series. The samples of wastewater and sludge were digested using nitric acid and placed into a Parr-type bomb for 4 h at 110 degrees C. Mercury was measured by Cold Vapour Atomic Absorption Spectrometry (CV-AAS) at 253.7 nm with sodium tetrahydroborate as reductant. The methodologies were checked with an USEPA quality control sample, a standard reference material from NIST and with another method of mineralization (cold mineralization) showing good results. Concentrations of mercury in wastewater between 1.47 +/- 0.75 microgl(-1) have been found at the entrance of the system and 0.74 +/- 0.0 microgl(-1) at the exit, while in sludge the results were between 0.29 +/- 0.12 microgkg(-1) in the facultative pond and 0.04 +/- 0.02 microgkg(-1) in the second maturation pond (exit). 相似文献
97.
Preparation and Characterization of Electrodes Modified with Pyrrole Surfactant,Multiwalled Carbon Nanotubes and Metallophthalocyanines for the Electrochemical Detection of Thiols 下载免费PDF全文
Magdalena Rangel Argote Elizabeth Sánchez Guillén Ana Gabriela Gutiérrez Porras Oracio Serrano Torres Cyrille Richard José H. Zagal Fethi Bedioui Silvia Gutierrez Granados Sophie Griveau 《Electroanalysis》2014,26(3):507-512
Our aim was to prepare hybrid electrodes active towards the electrooxidation of thiols by the co‐immobilization of native carbon nanotubes (CNTs) and cobalt phthalocyanine (CoPc) from aqueous solutions. This strategy was adopted to avoid the oxidation of CNTs that can induce a modification of their exceptional properties. To do so, a hydrosoluble pyrrole surfactant was used to get homogeneous aqueous dispersions of CNTs and CoPc and to trap both materials on the electrode via the electropolymerization of the pyrrole surfactant. The hybrid electrodes exhibit a good electrocatalytic activity towards the oxidation of L ‐cysteine and glutathione. Their performances in terms of limit of detection (0.01 mM) are compatible with the detection of these thiols in biological samples. 相似文献
98.
A study was undertaken to evaluate the content and distribution of eight key elements, namely, As, Cd, Co, Cu, Hg, Mn, Pb and Se in liver, kidney and muscle of chick individuals of Adélie penguin (Pygoscelis adeliae). Samples were collected during the 2002/2003 austral summer season campaign around Jubany Station (Argentine scientific station), Potter Cove, King George Island. Solutions of organs were prepared by acid-assisted microwave (MW) digestion by employing HNO3 and H202. Instrumental techniques selected to analyze the different tissues were inductively coupled plasma optical emission spectroscopy (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS). A wide range of elements retention capacity among the different organs was observed and the ranges ascertained are as follows (in μg g− 1): As, 0.5 (liver)-0.8 (muscle); Cd, < 0.07 (muscle)-3.4 (kidney); Co, 0.07 (liver)-0.7 (muscle); Cu, 0.6 (muscle)-18 (liver); Hg, 0.2 (kidney)-2.7 (liver); Mn, 1.5 (muscle)-10 (liver); Pb, 0.1 (muscle)-2.0 (liver); Se, 3.0 (muscle)-8.4 (liver). The observed trend in metal accumulation in the three organs of chick penguins was in the order Cu > Mn > Se ? As > Co > Pb ? Cd > Hg. Levels of metals and metalloids were, in general terms, higher in liver that is a specific target organ for metal accumulation. This study aimed at contributing to the establishment of base-line data on potential pollutants of ecotoxicological interest in the Antarctic ecosystem. 相似文献
99.
A review on the use of fluorescence polarization in immunoassay procedures is presented. Only the determination of low molecular-weight substances, such as therapeutic agents, drugs of abuse and hormones is considered because the measured change in fluorescence polarization depends on the molecular size of the analyte. The study emphasizes and appraises the analytical features of the methods so far proposed. 相似文献
100.
Grotjahn DB Van S Combs D Lev DA Schneider C Rideout M Meyer C Hernandez G Mejorado L 《The Journal of organic chemistry》2002,67(26):9200-9209
Syntheses of pyrazoles featuring a functionalized side chain attached to carbon 3 and varying alkyl and aryl substituents attached to carbon 5 are presented. Installation of R = methyl, isopropyl, tert-butyl, adamantyl, or phenyl groups at C5 is reported here, starting by coupling protected alkynols with acid chlorides RCOCl, forming alkynyl ketones, which are reacted with hydrazine to form the pyrazole nucleus. Alcohol deprotection and conversion to a chloride gave 5-substituted 3-(chloromethyl)- or 3-(2-chloroethyl)pyrazoles. This sequence can be done within 2 d on a 30 g scale in excellent overall yield. Through nucleophilic substitution reactions, the chlorides are useful precursors to other polyfunctional pyrazoles. In the work here, derivatives with side chains LCH(2)- and LCH(2)CH(2)- at C3 (L = thioether or phosphine) were made as ligands. The significance of the ligands made here is that by placing a ligating side chain on a ring carbon (C3), rather than on a ring nitrogen, the ring nitrogen not bound to the metal and its attached proton will be available for hydrogen bonding, depending on the steric environment created by R at C5. 相似文献