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101.
For any set ={f
1,f
2,...,f
s} ofC
3-functions on the interval [–1, 1], and for any weight functionw(x) satisfyingL
1w(x)L
2(1–|x|)(L
1,L
2>0, 0) and
, we give a constructive proof for the existence of quadrature formulas of the type
相似文献
102.
Dieter Seebach Rolf Dach Dieter Enders Bernd Renger Martin Jansen Gerold Brachtel 《Helvetica chimica acta》1978,61(5):1622-1647
1, 4, 5, 6-Tetrahydro-ν-tetrazin-Derivate The title compounds 2 and 13 are readily available from α-lithiated N-alkyl-nitrosoamines 1 (see Tables 1 and 2) which decompose at ? 73° to yield the N-oxides 2. The ESR. spectra of two derivatives 1 are recorded (Fig. 1), and tentative mechanisms are proposed for the head to head dimerizations ( la- 3- 4- 5- 2a and Scheme 1). Coupling of lithionitrosoamines with iodine (-6) and alternative decomposition routes of representatives of this class of organometallics with special substitution [equations (2)-(5)] are reported. The structures of the tetrazines are established by spectroscopic data [ESCA] (Fig. 2), IR., UV., 1H- (cf. Fig. 9) and 13C-NMR., PE. (Scheme 2), by an X-ray analysis of 2a (Fig. 4-8 and Table 3), and by the chemical reactions. The crystal structure of 2a is a twisted boat with non planar terminal nitrogen atoms which reflects the electron repulsion in the 4-atom-6-electron N? N?N?N-system. Comparisons are made with 2-tetrazenes, the open chain analogues of 13 , wherever possible. Raney-Ni reductions of 2 or 13 gives diamines 14 to which is assigned the d, l-configuration through the 1H-NMR. spectra of the aminals 7 and 15 . Neither the oxides 2 nor the tetrazines 13 undergo cycloaddition reactions [equation (6) and Section 4]. Compound 2a is dimerized to the bis (nitrosoamino)-2-tetrazene 18 by treatment with acid, ZnII, CuI or iodomethane. 2a is oxidized at nitrogen to the ethylene diamine derivative 6a (through 20 , with H2O2), or at the CH2-groups of the ring to give oxo-N-oxide 21 (with MnO2 or the ring contracted oxo-tetrazoline-N-oxide 22 (with KMnO4). Pyrolysis or photolysis of the dimethyl tetrahydrotetrazine 13a furnishes the trimer 26 of N-methylimine, but no diazetidine 27 . Silver and mercury complexes 29 are obtained from 13a , while Cr(CO)5. THF does not furnish a complex as with azocompounds, but rather replaces N2 in 13a by CO (→ 28). Oxidation with permanganate converts 13a into the oxalic acid derivative 30 with unchanged tetrazine structure. 相似文献
103.
Analysis of the quorum-sensing regulon of the opportunistic pathogen Burkholderia cepacia H111 by proteomics 总被引:3,自引:0,他引:3
Burkholderia cepacia H111, an important pathogen for persons suffering from cystic fibrosis, employs a quorum-sensing (QS) system, cep, to control expression of virulence factors as well as the formation of biofilms. The QS system is thought to ensure that pathogenic traits are only expressed when the bacterial population density is high enough to overwhelm the host before it is able to mount an efficient response. In this study, we compared the protein pattern of the intracellular, extracellular, and surface protein fractions of an AHL-deficient cepI mutant with the one of the parent strain H111 by means of two-dimensional gel electrophoresis (2-DE). Our analysis showed that 55 proteins out of 985 detected spots were differentially expressed; these are expected to represent QS-controlled gene products. Addition of the respective signal molecules to the growth medium of the cep mutant fully restored the wild-type protein expression profile. In total about 5% of the B. cepacia proteome was downregulated and 1% upregulated in the cepI mutant, indicating that quorum sensing represents a global regulatory system. Nineteen proteins were identified with high confidence by N-terminal sequence analysis. 相似文献
104.
Günther J. Redhammer Gerold Tippelt Daniel Rettenwander 《Acta Crystallographica. Section C, Structural Chemistry》2022,78(1):1-6
Single crystals of an Li-stuffed, Al- and Ga-stabilized garnet-type solid-state electrolyte material, Li7La3Zr2O12 (LLZO), have been analysed using single-crystal X-ray diffraction to determine the pristine structural state immediately after synthesis via ceramic sintering techniques. Hydrothermal treatment at 150 °C for 28 d induces a phase transition in the Al-stabilized compound from the commonly observed cubic Iad structure to the acentric I3d subtype. LiI ions at the interstitial octahedrally (4 + 2-fold) coordinated 48e site are most easily extracted and AlIII ions order onto the tetrahedral 12a site. Deep hydration induces a distinct depletion of LiI at this site, while the second tetrahedral site, 12b, suffers only minor LiI loss. Charge balance is maintained by the incorporation of HI, which is bonded to an O atom. Hydration of Ga-stabilized LLZO induces similar effects, with complete depletion of LiI at the 48e site. The LiI/HI exchange not only leads to a distinct increase in the unit-cell size, but also alters some bonding topology, which is discussed here. 相似文献
105.
The crystal structure of Cr2H2(As2O7)(As4O12) has been determined by X-ray methods using single crystal diffractometer data (1,152 reflections,R=0.054, orthorhombic,Pmmn,a=1317.7 (7),b=1124.9 (6),c=494.3 (4) pm,Z=2). The crystal structure contains both diarsenate(V) and the hitherto unknown cyclo-tetraarsenate(V)-anions. The magnetic susceptibility follows theCurie-Weiss law (=3.86±0.01 B/Cr3+, =–31 K). 相似文献
106.
107.
Reactions of triaminophosphane (R2N)2P–NH2, (R = 1Pr) 1a, with aminodihalogenophosphanes 1Pr2N–PX2, 2a–c [X = CL (a), Br (b), I(c)], in the presence of a base yielded the P-hydrogeno-iminophosphoranyl-halogenophosphanes (R2N)2PH = N–PX–N(1Pr)2 4a–c [X = Cl (a), Br (b), I(c)]. Analogous reactions between 1a and 1b (b: R = c-hexyl) and chloroiminophosphane (Cl–P = N–Mes*, (Mes* = 2,4,6-tBu3C6H2) 6 , gave the P-hydrogeno(iminophosphoranyl)-σ2,λ3-iminophosphanes, (R2N)2PH = N–P = N–Mes* 8a and 8b. In solution 8a, 8b eliminated amine, yielding σ2, λ3-iminophosphanyl-substituted 1,3,2,4-diazadiphosphetidines [(R2N)PN(P = N–Mes*)]2, 10a, 10b , and 11 ( 10a and 10b : cis; 11: trans). The X-ray structure analyses of compounds 4a, 4b, 8a, and 11 are discussed. © 1996 John Wiley & Sons, Inc. 相似文献
108.
109.
Gerold Filscher 《Crystal Research and Technology》1977,12(12):1311-1317
In dependence on crystal altitude, Bragg angle and distance focus-crystal the necessary accuracy of crystal adjustment is calculated on condition that with illumination of the full crystal height the Kα-doublet is separable. In this connection a critical crystal altitude for the Lang-topography is stated, which requires a faultless adjustment of the net plane. For the real altitude of crystal resp. film adequate demands for adjustment are derived. A simple diffractometer device for external crystal adjustment if described and the attainable accuracy is indicated. 相似文献
110.
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