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931.
932.
Stefan Zawadzki Andrzej Wijata 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):307-311
Abstract The convenient synthesis of N-phosphorylated formamidines, 3 based on the reaction c diethyl(ethoxymethylene)phosphoramidate, 1 with primary and secondary amines is described. 相似文献
933.
Hartmut Komber Gisbert Grossmann Axel Kretschmer 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):335-343
Abstract Compounds of the following structure (R1O)2(X)P[sbnd]Y–P(X)(OR2)2 (X = O, Y = Sn (n = 1–4), R1 = R2 = Me, iPr; X = S, Y = Sn (n = 1–4), R1, R2 = Me, Et, iPr, iBu; X = S, Y = S-Se-S, S-Te-S, R1 = R2 = Me were prepared and their NMR spectra were analysed. Depending on the number of sulfur atoms, bonded between the phosphorus atoms, typical ranges of the P-P coupling constants were found for the different sulfanes investigated: 2JPP from-10 to-20 Hz, 3JPP less than 3 Hz, 4JPP from +10 to +13 Hz and 5JPP less than 1 Hz. For the small vicinal coupling constants and the relatively large values of 4JPP different possibilities of their interpretation are given. 相似文献
934.
Tongdao Wang Dr. Hong Zhang Feifei Han Lipeng Long Prof. Dr. Zhenyang Lin Prof. Dr. Haiping Xia 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(33):10982-10991
Alkali‐resistant osmabenzene [(SCN)2(PPh3)2Os{CHC(PPh3)CHCICH}] ( 2 ) can undergo nucleophilic aromatic substitution with MeOH or EtOH to give cine‐substitution products [(SCN)2(PPh3)2Os{CHC(PPh3)CHCHCR}] (R=OMe ( 3 ), OEt( 4 )) in the presence of strong alkali. However, the reactions of compound 2 with various amines, such as n‐butylamine and aniline, afford five‐membered ring species, [(SCN)2(PPh3)2Os{CH?C(PPh3)CH?C(CH?NHR′)}] (R′=nBu( 8 ), Ph( 9 )), in addition to the desired cine‐substitution products, [(SCN)2(PPh3)2Os{CHC(PPh3)CHCHC(NHR′)}] (R′=nBu( 6 ), Ph( 7 )), under similar reaction conditions. The mechanisms of these reactions have been investigated in detail with the aid of isotopic labeling experiments and density functional theory (DFT) calculations. The results reveal that the cine‐substitution reactions occur through nucleophilic addition, dissociation of the leaving group, protonation, and deprotonation steps, which resemble the classical “addition‐of‐nucleophile, ring‐opening, ring‐closure” (ANRORC) mechanism. DFT calculations suggest that, in the reaction with MeOH, the formation of a five‐membered metallacycle species is both kinetically and thermodynamically less favorable, which is consistent with the experimental results that only the cine‐substitution product is observed. For the analogous reaction with n‐butylamine, the pathway for the formation of the cine‐substitution product is kinetically less favorable than the pathway for the formation of a five‐membered ring species, but is much more thermodynamically favorable, again consistent with the experimental conversion of compound 8 into compound 6 , which is observed in an in situ NMR experiment with an isolated pure sample of 8 . 相似文献
935.
Dr. Niels J. M. Pijnenburg Dr. Yves H. M. Cabon Prof. Dr. Gerard van Koten Prof. Dr. Robertus J. M. Klein Gebbink 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(15):4858-4868
This paper describes a mechanistic study of the SCS‐pincer PdII‐catalyzed auto‐tandem reaction consisting of the stannylation of cinnamyl chloride with hexamethylditin, followed by an electrophilic allylic substitution of the primary tandem‐reaction product with 4‐nitrobenzaldehyde to yield homoallylic alcohols as the secondary tandem products. As it turned out, the anticipated stannylation product, cinnamyl trimethylstannane, is not a substrate for the second part of the tandem reaction. These studies have provided insight in the catalytic behavior of SCS‐pincer PdII complexes in the auto‐tandem reaction and on the formation and possible involvement of Pd0 species during prolonged reaction times. This has led to optimized reaction conditions in which the overall tandem reaction proceeds through SCS‐pincer PdII‐mediated catalysis, that is, true auto‐tandem catalysis. Accordingly, this study has provided the appropriate reaction conditions that allow the pincer catalysts to be recycled and reused. 相似文献
936.
萘甲酸功能化聚砜的制备及其与Eu(Ⅲ)稀土离子配合物的荧光发射特性 总被引:3,自引:2,他引:1
以1,4-二氯甲氧基丁烷(BCMB)为氯甲基化试剂,使聚砜(PSF)氯甲基化(CM),形成氯甲基化聚砜(CMPSF),然后用6-羟基-2-萘甲酸(HNA)使CMPSF的氯甲基与HNA的酚羟基之间发生亲核取代反应,将萘甲酸(NA)配基键合在聚砜侧链,制得了功能化改性的聚砜NAPSF。采用红外光谱和核磁共振氢谱对其结构进行了表征。考察了主要因素对CMPSF与HNA之间亲核取代反应的影响规律,分析了反应机理,优化了反应条件。结果表明,CMPSF与HNA之间取代反应的速率与亲核试剂HNA的浓度无关,遵循SN1的反应机理;使用极性较强的溶剂二甲亚砜,有利于亲核取代反应的进行;在适宜条件下,CMPSF的氯甲基转化率可达96%,NA的键合量为1.68 mmol/g。将NAPSF与Eu(Ⅲ)离子配位,制得了聚合物-稀土配合物NAPSF-Eu(Ⅲ),它不仅发射出Eu3+离子的特征荧光,而且对Eu3+离子的荧光发射显示出很强的敏化作用。萘甲酸功能化的大分子配基NAPSF对Eu3+离子的敏化作用,远强于苯甲酸(BA)功能化的大分子配基BAPSF对Eu3+离子的敏化作用。 相似文献
937.
Derivation of saddle shaped cyclooctatetrathiophene: increasing conjugation and fabricating pentamer
With cyclooctatetrathiophene (COTh) as building block, two α,α,α,α-tetraaryl COThs, COThP and COThTh have been efficiently synthesized. Phenyl and thienyl were employed as end-capping groups to introduce to COTh and increase its conjugation. For enlarging the special ‘saddle’ shaped structure, a pentamer of COTh was synthesized via Negishi reaction and CuCl2-promoted oxidative coupling reaction. The pentamer (COThF) is a new type of dendrimer with COTh as dendron, which presents an artistic configuration possessing a large saddle shape. All compounds were fully characterized by 1H NMR, 13C NMR, HRMS and IR. The crystal structures of COThP and COThTh were confirmed by X-ray analysis. The molecular configuration of COThF was optimized by theoretical calculations. Their UV–vis properties, electrochemical behaviours and thermo-gravimetric analysis of COThP, COThTh and COThF were also described. 相似文献
938.
Shunji Ito Shohei Yamazaki Shun Kudo Ryuta Sekiguchi Jun Kawakami Masayuki Takahashi Takashi Matsuhashi Kozo Toyota Noboru Morita 《Tetrahedron》2014
Three new 1,2-dihydro-1-oxabenz[a]azulen-2-one derivatives, 1a (R1=H, R2=Me), 1b (R1=H, R2=Ph), and 1c (R1=COOEt, R2=Me), have been synthesized by the reaction of 2-hydroxyazulene (2a) and its 1-ethoxycarbonyl derivative 2b with ethyl acetoacetate (3a) or ethyl benzoylacetate (3b) in the presence of aluminum chloride. To our knowledge, these are the first examples of this type of compound, although the yield of the products is low in some cases. Their electronic properties were studied in detail utilizing the analyses of 1,2-dihydro-1-oxabenz[a]azulen-2-one derivative 1a by the spectroscopic and voltammetric analyses. The analyses revealed that the fused α-pyrone system lowers both the HOMO and the LUMO energies, relative to those of parent azulene (10), but has much pronounced effect on the LUMO, consequently, leading to decrease in HOMO–LUMO gap, compared with those of 10. These results should be attracted to the development of amphoteric redox materials. Reactivity toward electrophilic reagents was also examined by bromination and Vilsmeier–Haack formylation reactions of 1a. To evaluate the scope of the reaction products we have examined Sonogashira cross-coupling reaction of the bromination products with trimethylsilylacetylene and conversion of the formylation product to dibromoolefin by the reaction with phosphorous ylide prepared with CBr4 and Ph3P. Effective extension of the π-electron system in the ethynyl products has been revealed by the spectroscopic analysis. These reaction products would be attracted to the application as a terminal group for electronic applications. 相似文献
939.
940.