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41.
S. Caroli O. Senofonte S. Caimi P. Pucci J. Pauwels G. N. Kramer 《Analytical and bioanalytical chemistry》1998,360(3-4):410-414
The preparation of new Certified Reference Materials (CRMs) of antarctic matrices forms the backbone of an ongoing project
in the framework of the Italian National Program for Antarctic Research. The first CRM of this kind (MURST-ISS-A1 Antarctic
Marine Sediment) is already available. The second phase focuses on the certification of antarctic krill, a small shrimp extremely
abundant in the Southern Ocean. The total mass of krill available for this purpose is approximately 44 kg and results from
the combination of three different catches (Ross Sea, Marguerite Bay and Livingston Island, respectively). The quantification
of the following elements in the raw mass appears to be affordable by current analytical techniques, values being in the range
of (in μg/g) 0.11–0.30 for As, 0.03–0.12 for Cd, 0.06–0.23 for Cr, 6.1–21 for Cu, 5.7–7.6 for Fe, 0.005–0.008 for Hg, 0.7–1.2
for Mn, 0.013– 0.077 for Ni, 0.04–0.57 for Pb and 12–16 for Zn. On the other hand, the average values ascertained in freeze-dried
krill are as a rule one order of magnitude higher, i.e., (in μg/g), 3.2 for As, 0.6 for Cd, 1.8 for Cr, 75 for Cu, 61 for
Fe, 0.025 for Hg, 4.6 for Mn, 0.7 for Ni, 2.1 for Pb and 81 for Zn. Information on the pretreatment of krill and details on
the planned certification campaign are also given.
Received: 10 June 1997 / Revised: 24 September 1997 / Accepted: 28 September 1997 相似文献
42.
U. Steiner M. Hafner S. Schreiner H. E. A. Kramer 《Photochemistry and photobiology》1974,19(2):119-128
Abstract— While studying the photoreduction of some dyes (D) by reducing agents (R), it was observed that the quantum yield of the photoreduction increases considerably upon addition of a third substance (C), whereas it is very small when the dye is photoreduced by C alone (catalytic effect), (see Table 1).
The system thionine (D), allylthiourea (R), and azulene (C) was investigated in detail using both flash photolysis and continuous illumination. On photolysis, thionine is converted into its photo-reduced form, leucothionine. Azulene reacts with the basic form of the thionine triplet3 TH + to produce the semithionine radical. In the system thionine and azulene, most of these radicals revert back to thionine. When ATU (˜ 102- M ) is added to thionine and azulene (3 × 10-4 M ), the semithionine radicals are reduced to leucothionine; the quantum yield of this reduction is considerably higher than in the system thionine and allylthiourea. Flash experiments demonstrate that allylthiourea does not react with the semithionine radicals.
At very high ATU concentrations (≥ 10-1 M ), however, the primary reaction is between thionine triplet and allylthiourea; under these conditions the quantum yield is not influenced by azulene (3 × 10-4 M ). 相似文献
The system thionine (D), allylthiourea (R), and azulene (C) was investigated in detail using both flash photolysis and continuous illumination. On photolysis, thionine is converted into its photo-reduced form, leucothionine. Azulene reacts with the basic form of the thionine triplet
At very high ATU concentrations (≥ 10
43.
Thedc-conductivity of the one-dimensional Anderson model of a disordered system is investigated with two independent numerical methods for systems as large as 104 sites starting from Kubo's formula. In contradiction to the conventional theory of one-dimensional disordered systems a non zero conductivity for finite values of the disorder parameterW/V is found. the eigenstates of the system are investigated. Results for the inverse participation number and the mean square extension of the states are given and compared with the results for the conductivity.Work supported by the Deutsche Forschungsgemeinschaft (SFB 125 Köln and Project No. Kr627/2) 相似文献
44.
Zusammenfassung Aus der Gruppe der Dibenzoazepinderivate wurden die Hydrochloride von Clomipramin, Imipramin und Desipramin miteinander kombiniert und aus der Gruppe der Dibenzocykloheptadiene bzw.-triene die Hydrochloride von Amitriptylin, Nortriptylin, Noxiptilin und Protriptylin.Bei fünf der untersuchten binären Systeme liegt Mischkristallbildung aufgrund von Isomorphiebeziehungen mit instabilen Modifikationen vor: Imipraminhydrochlorid — Clomipraminhydrochlorid, Imipraminhydrochlorid — Desipraminhydrochlorid, Clomipraminhydrochlorid — Desipraminhydrochlorid, Nortriptylinhydrochlorid — Protriptylinhydrochlorid und Noxiptilinhydrochlorid-Amitriptylinhydrochlorid. Das Substanzpaar Protriptylinhydrochlorid — Noxiptilinhydrochlorid bildet eine Molekülverbindung im Verhältnis 11. In drei Fällen werden einfache Eutektika gebildet.
Thermoanalytical investigations of psychotropic substances derived from phenothiazine and butyrophenones for isomorphism and polymorphism. II
Summary From the group of dibenzoazepine derivatives, the hydrochlorides of clomipramine, imipramine and desipramine were combined with each other and from the group of dibenzocycloheptadienes or -trienes the hydrochlorides of amitriptyline, nortriptyline, noxiptiline and protryptiline. In five of the binary systems investigated, there is formation of mixed crystals due to isomorphism with unstable modifications: imipramine hydrochloride — clomipramine hydrochloride, imipramine hydrochloride — desipramine hydrochloride, clomipramine hydrochloride 3- desipramine hydrochloride, nortriptyline hydrochloride — protriptyline hydrochloride and noxiptiline hydrochloride — amitriptyline hydrochloride. The substance pair protriptyline hydrochloride — noxiptiline hydrochloride forms a molecular compound in the ratio 11. In three cases, simple eutectics are formed.相似文献
45.
H. Kaupp H. -P. Didra C. Kramer M. Baumann 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,27(4):307-312
Depolarization of excited114Cd 5s5p 3 P 1 atoms induced by collisions with various molecular gases (N2, H2, D2, CO, CO2, CH4, C2H6, C2H4) has been investigated using polarized fluorescence spectroscopy. After pulsed optical excitation of the Cd 53 P 1 level with appropriately polarized light the temporal behaviour of Zeeman quantum beats has been observed showing the influence of collisional destruction of orientation and alignment. By analyzing the signal curves at different molecular gas pressures the corresponding depolarization cross sections for114Cd atoms in the 53 P 1 state have been obtained. With regard to a test of a nuclear spin decoupling model for the collisions the cross sections were compared with previously measured hyperfine structure transfer cross sections of113Cd 5s5p 3 P 1 atoms. 相似文献
46.
Petra Schulte Gunther Schmidt Claus-Peter Kramer Adolf Krebs Ulrich Behrens 《Journal of organometallic chemistry》1997,530(1-2):95-100
The strained cycloheptynes 2a, 2b and 2c react with copper(I) chloride to form the dinuclear complexes [CuCl(cycloheptyne)]2 3a, 3b and 3c respectively. X-ray diffraction studies on all three compounds 3 show an increase in strength of the copper-alkyne bond with increasing deformation of the alkyne moiety from the ideal 180°. Thus going from the least strained alkyne (2c) to the most strained one (2a), the Cu-C bond lengths in the corresponding complexes decrease from 197.5 pm (3c) to 194.9 pm (3a). The C≡C-C angles increase from 145.6° (3a) over 147.4° (3b) to 151.6° (3c).
Zusammenfassung
Die gespannten Cycloheptine 2a, 2b und 2c reagieren mit Kupfer(I)—chlorid unter Bildung der zweikernigen Komplexe [CuCl(cycloheptin)]2 3a, 3b und 3c. Röntgenstrukturanalysen von allen drei Verbindungen 3 zeigen, daβ die Stärke der Kupfer—Alkin-Bindung zunimmt je mehr das ganze Alkinsystem vom idealen 180°-Winkel abweicht. Geht man vom am wenigsten gespannten Alkin (2c) zum gespanntesten (2a), so nehmen die Cu-C-Bindungslängen in den entsprechenden Komplexen von 197.5 pm (3c) auf 194.9 pm (3a) ab. Die C≡C-C-Winkel werden von 145.6° (3a) über 147.4° (3b) nach 151.6° (3c) hin gröβer. 相似文献
47.
B. M. K. Nefkens S. D. Adrian D. B. Barlow P. DiBernardo A. D. Eichon R. S. Kessler J. N. Labrenz C. Pillai J. W. Price J. A. Wightman W. J. Briscoe L. H. Kramer M. F. Taragin D. F. Ottewell 《Few-Body Systems》1992,12(2-4):133-140
First results on –
d are reported. The measurements were made using 8 specially designed neutron counters, which were carefully calibratedin situ. The differential cross sections atT
=142, 180, 217, and 254 MeV were obtained at four angles between 0° and 90°, they are compared to +
d pp data measured at the same energies and angles with the same setup. At every beam energy, the shape of the angular distributions of –
d nn and +
d pp is the same to ±2%. The absolute cross sections differ by 1 to 10%. The error in this comparison is ±4% implying a small violation of charge symmetry.Dedicated to Prof. I. laus on the occasion of his 60th birthdayDeceased 相似文献
48.
49.
We discuss the scale dependence of
s
in connection with jet multiplicities on theZ pole in the framework of perturbative QCD. Several scale defining procedures are applied to jet fractions and compared to recent measurements at LEP.Dedicated to Prof. Dr. H.J. Mang on the occasion of his 60th birthday 相似文献
50.