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171.
Reaction of A2CO3 (A = K, Rb) with Sn and Se in an H2O/CH3OH mixture at 115–130°C affords the isotypic selenidostannates(IV) A6Sn4Se11 _. xH2O (A = K, x = 8) 1 and 2 whose discrete [Sn4Se11]6– anions each contain two corner‐bridged ditetrahedral [Sn2Se6]4– species. Similar reaction conditions with A = Cs afford Cs2Sn2Se5 _. H2O ( 3a ) and Cs2Sn2Se5 ( 3b ) in which such [Sn2Se6]4– building blocks are connected through common Se atoms into infinite [Sn2Se52–] chains. The [Sn3Se72–] ribbons of (Et4N)2Sn3Se7 ( 4 ), formed by treating (Et4N)I with Sn and Se in methanol at 130°C, can be regarded as resulting from the condensation of [Sn2Se52–] chains with molecular [SnSe4]4– anions. The anions [Sn4Se11]6–, [Sn2Se52–], and [Sn3Se72–] represent the products of individual reaction steps on the potential condensation pathway of [Sn2Se6]4– to the lamellar selenidostannates(IV) [Sn4Se92–] or [Sn3Se72–]. 相似文献
172.
Polysulfonylamines. CXI. The First X‐Ray Structures of Cationic Diorganyltin(IV) Dichelates [R2Sn(L–L)2]2⊕ Involving Bidentate Phosphine Oxide Ligands: Di(methanesulfonyl)amide as a Non‐Coordinating Counter‐Ion The reaction of Me2Sn(A)2, where A⊖ = (MeSO2)2N⊖, with DPPOE = ethane‐1,2‐diylbis(diphenylphosphine oxide) or CDPPOET = cis‐ethene‐1,2‐diylbis(diphenylphosphine oxide) yields the ionic dichelates [Me2Sn(dppoe)2]2⊕ · 2 A⊖ ( 1 ; monoclinic, space group P21/c) and [Me2Sn(cdppoet)2]2⊕ · 2 A⊖ ( 2 ; monoclinic, P21/n). A solvated variety of 2 , [Me2Sn(cdppoet)2]2⊕ · 2 A⊖ · Et2O · 0.15 MeCN ( 4 ; triclinic, P 1), was serendipitously obtained by thermal degradation of the new compound [Me2Sn(A)(μ‐OH)]2 · 2 CDPPOET in an MeCN/Et2O medium. The crystals of 1 , 2 and 4 consist of discrete formula units (one independent unit for 1 and 2 , two independent units for 4 ); in the structure of 4 , the solvent molecules are located in lattice cavities. All the tin atoms lie on crystallographic inversion centres and display moderately distorted octahedral C2O4 coordinations with short Sn–O bonds in the range 218–223 pm. Within the formula units, the anions are connected to the P–CH donor groups of the chelating ligands by C–H…O/N interactions, some of which are remarkably short (e.g. in 1 : H…O 220 pm, C–H…O 170°; H…N 242 pm, C–H…N 153°). 相似文献
173.
Nils Wiberg Hans-Wolfram Lerner Heinrich Nth Werner Ponikwar 《Angewandte Chemie (International ed. in English)》1999,38(8):1103-1105
Dark violet hexastannane ( t Bu 3 Si) 6 Sn 6 displays a new framework motif for molecular tin compounds, in which six Sn atoms are located at the corners of a trigonal prism. The compound can be synthesized according to Equation (a). R*=SitBu3. 相似文献
174.
《Arabian Journal of Chemistry》2019,12(5):610-620
In this paper pH sensors based on tetra-metal oxide system (TMOF) film was synthesized by branched cathodic electrodeposition technique. Four different metal oxides mainly IrO2, RuO2, SnO2, and TiO2 used to form a film, which coated on various substrates such as titanium, steel, tin, and copper. The fabricated pH sensors underwent characterization and evaluation sensing performance. Characterizations results have indicated that titanium and steel substrates outperform alternative metal substrates Tin and copper. Nernstian performance of Steel and Titanium substrate with pH sensitivity ∼59 mV/pH remain the same, as well as tin and copper which are behaved as super-Nernstian with sensitivity ∼65 mV/pH. Fast response time ranged from 1 to 3 s were obtained. Perfect selectivity obtained using Na+, K+, Li+ and Mg2+ ions vs. primary one H+. 相似文献
175.
《Particuology》2018
Tin dioxide is a useful n-type oxide semiconductor used in a variety of applications owing to its superior optical, electrical, and multifunctional properties. Here, we used a network of resorcinol–formaldehyde (RF) gel to synthesize mesoporous tin dioxide via a sol–gel process. The effects of various synthesis parameters on the morphology and mesoporosity of the obtained product were investigated, including aging time of the RF gel, tin-to-formaldehyde molar ratio, resorcinol-to-carbonate molar ratio, and the aging time of the tin/RF mixed gel. Our experimental results showed that the interaction between the network of the RF gel and tin-containing sol is a key factor that affected the structural strength of the porous network and the porosity of the final product. Through control of the interactions in the tin/RF mixed gel we obtained porous tin dioxide materials that could be effectively used to form large-surface area films with desirable mesoporous properties. 相似文献
176.
D.H. Delphenich 《Annalen der Physik》2009,18(4):206-230
The mechanics of wave motion in a medium are founded in conservation laws for the physical quantities that the waves carry, combined with the constitutive laws of the medium, and define Lorentzian structures only in degenerate cases of the dispersion laws that follow from the field equations. It is suggested that the transition from wave motion to point motion is best factored into an intermediate step of extended matter motion, which then makes the dimension‐codimension duality of waves and trajectories a natural consequence of the bicharacteristic (geodesic) foliation associated with the dispersion law. This process is illustrated in the conventional case of quadratic dispersion laws, as well as quartic ones, which include the Heisenberg–Euler dispersion law. It is suggested that the contributions to geodesic motion from the non‐quadratic nature of a dispersion law might represent another source of quantum fluctuations about classical extremals, in addition to the diffraction effects that are left out by the geometrical optics approximation. 相似文献
177.
178.
Nari N. Talaty Kristina Beck Helene Citeau Kristin Kirschbaum Dean M. Giolando Prof. Dr. 《无机化学与普通化学杂志》2009,635(1):53-63
A new single‐source precursor, [SnCl4{OC(H)OC2H5}2], prepared by treating tin tetrachloride with ethyl formate (1:2 ratio) was developed for the deposition of tin oxide thin films on glass substrates. The compound [SnCl4{OC(H)OC2H5}2] is highly volatile and provides very high growth rates (up to 100Å s?1 at 560 °C) in an atmospheric pressure chemical vapor deposition (APCVD) reactor. More significantly, the compound does not decompose to tin oxide below 320 °C, thereby minimizing the formation of particles in the vapor above the growing tin oxide film. To prepare highly conducting fluorine doped tin oxide (SnO2:F) films 2,2,2‐trifluoroethyl trifluoroacetate was used as the source of fluoride. High quality SnO2:F films were deposited at 560 °C with a flow rate of 2 mL fluoride reagent hr?1; typical film properties are resistivity of 5.9 X 10?4 Ω cm, Hall mobility of 27.3 cm2 V?1 s?1, carrier concentration of 3.9 X 1020 cm?3 and percent transmission ranging from 86 to 88 %. The best films of SnO2:F possess transparencies as high as 90 % (750 nm), sheet resistances as low as 7 Ω sq?1 and Haacke's figure of merit as high as 29 X 10?3 (750 nm). The newly developed APCVD reactor and the chemistry were optimized with respect to structural, electrical and optical properties of the films by adjusting the substrate temperature, gas flow rates and the amount of fluoride present in the vapor stream. Growth rates with respect to deposition time, substrate temperature and flow rates of precursors were found to be similar for both undoped (SnO2) and doped (SnO2:F) samples. The SnO2:F films possess larger grains than the SnO2 which may account for the lower resistivity and the higher mobility in the SnO2:F samples. 相似文献
179.
The cationic surfactant, cetyltrimethyl ammonium bromide (CTAB) effect on accurate determination of dopamine in the presence of ascorbic acid (as natural obtrusive in determination of dopamine) using chemically modified electrode based on tin hexacyanoferrate (SnHCF) as a modifier at carbon paste electrode (CPE) is described. The electrochemical response of bare CPE and SnHCF modified electrode (ME) examined in different pHs, in absence and presence of different concentration of dopamine (DA) and ascorbic acid (AA). In addition a simple and reliable method for simultaneous electrochemical determination of AA and DA was presented. It was based on the use of the cationic surfactant CTAB that enables the separation of the oxidation peaks potential of AA and DA. The experimental results showed that DA and AA have two separate peaks. In pH 3 and at presence of 3 mM of CTAB the separation of DA and AA peaks and the eminence of them increased evidently. Good linear response to AA and DA was observed in the range of 0.4–50 and 0.2–25 mM with the correlation of 0.9912 and 0.9955, respectively. 相似文献
180.
Farhat Waqar Saida Jan Bashir Mohammad Muhammad Hakim Shah Alam Wasim Yawar 《中国化学会会志》2009,56(2):335-340
An analytical method has been developed for the preconcentration of rare earth elements (REEs) in seawater for their determination by inductively coupled plasma optical emission spectrometry (ICP‐OES). An indigenously synthesized chelating resin was used for the preconcentration of (REEs) which was based on immobilization of fluorinated β‐diketone group on solid support styrene divinyl benzene. Sample solutions (adjusted to optimized pH) were passed through a polyethylene column packed with 250 mg of the resin. Experimental conditions consisting of pH, sample flow rate, sample volume and eluent concentration were optimized. The established method has been applied for the preconcentration of light, medium and heavy REEs in coastal sea water samples for their subsequent determination by (ICP‐OES). Percentage recoveries of La, Ce, Nd, Sm, Eu, Gd, Dy, Er, Yb and Lu were ≥ 95%, a preconcentration factor of 200 times, and relative standard deviations < 5% were achieved. 相似文献