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101.
Zhu XH Mercier N Frère P Blanchard P Roncali J Allain M Pasquier C Riou A 《Inorganic chemistry》2003,42(17):5330-5339
2,2'-bithiophene derivatives, 5-ammoniumethylsulfanyl-2,2'-bithiophene (AESBT) and 5,5'-bis(ammoniumethylsulfanyl)-2,2'-bithiophene (BAESBT), have been designed for their incorporation in organic-inorganic materials based on iodometalates. Three layered compounds, (BAESBT)PbI(4), (AESBT)(4)Pb(3)I(10), and (AESBT)(3)Bi(2)I(9), have been synthesized as crystals from slowly cooled aqueous solution containing metal halide and bithiophene derivative salts. When starting from the diammonium cation, (BAESBT)PbI(4) hybrid perovskite is obtained. (BAESBT)PbI(4) adopts a triclinic cell (P1) with the lattice parameters a = 8.4741(5) A, b = 8.9255(6) A, c = 16.876(1) A, alpha = 88.328(5) degrees, beta = 81.806(4) degrees, gamma = 88.864(5) degrees, Z = 2. In the structure, PbI(4)(2)(-) perovskite sheets and diammonium cation layers alternate along c. The incorporation of the corresponding monoammonium cation (AESBT) leads to a head to tail arrangement of the molecules in the (AESBT)(4)Pb(3)I(10) hybrid, precluding the formation of the perovskite layers. (AESBT)(4)Pb(3)I(10) is orthorhombic, Pna2(1), with a = 38.333(4) A, b = 22.239(3) A, c = 8.448(2) A, Z = 4. The structure consists of corrugated layers of Pb(3)I(10)(4)(-) separated by organic layers of monoammonium cations. A similar relative situation of molecules in organic layers is observed in (AESBT)(3)Bi(2)I(9), with the inorganic sheets being built up from Bi(2)I(9)(3)(-) entities. (AESBT)(3)Bi(2)I(9) crystallizes in an orthorhombic cell (P2(1)2(1)2(1)) with a = 8.4564(6) A, b = 21.368(2) A, c = 30.747(2) A, Z = 4. In the three compounds, the molecular packings appear different, underlining the interplay between both organic and inorganic components. New packings are stabilized, as illustrated by an original mixed kappa-alpha type arrangement of the bithiophene units in (AESBT)(3)Bi(2)I(9). Furthermore, molecular interactions, especially of S.S type, appear stronger in the hybrids based on the monoammonium cations. The electrical conductivity of a (BAESBT)PbI(4) single crystal has also been investigated, revealing a semiconductive behavior with a characteristic energy of E(g) = 2.535 eV. 相似文献
102.
Gonçalves da Silva AM Romão RS Lucero Caro A Rodríguez Patino JM 《Journal of colloid and interface science》2004,270(2):417-425
The structural and dynamic characteristics of dioctadecyldimethylammonium bromide (DODAB) monolayers on a pure water subphase were investigated by surface film balance, Brewster angle microscopy, and relaxation in area and surface pressure at constant surface pressure and area, respectively. The first compression-expansion cycle of the monolayer is not reversible and the second pi-A compression isotherm deviates to larger molecular areas relative to the first one. At a microscopic level this hysteresis may be assigned to an irreversible hydration of the ammonium groups of DODAB. The morphology and reflectivity of DODAB monolayers during compression and expansion on the monolayer depend on the monolayer history. Bright domains randomly dispersed were observed during compression before collapse. Surprisingly, this random distribution of domains changes into a fractal-like structure during the monolayer expansion in a narrow range of surface pressures. This morphology does not form when the monolayer is previously compressed above the collapse surface pressure. 2D foam-like structure is often observed when the film is expanded at maximum area. Relaxation phenomena in DODAB monolayers are attributed to monolayer reorganization and nucleation of liquid-condensed domains from the liquid-expanded phase. These time-dependent processes are irreversible. 相似文献
103.
Amélia Messara Dr. Armen Panossian Dr. Koichi Mikami Dr. Gilles Hanquet Dr. Frédéric R. Leroux 《Angewandte Chemie (International ed. in English)》2023,62(10):e202215899
The deprotonative functionalization of α,α-difluoromethyl ketones is described herein. Using a catalytic organosuperbase and a silane additive, the corresponding difluoroenolate could be generated and trapped with aldehydes to deliver various α,α-difluoro-β-hydroxy ketones in high yields. This new strategy tolerates numerous functional groups and represents the access to the difluoroenolate by direct deprotonation of the difluoromethyl unit. The diastereoselective version of the reaction was also investigated with d.r. up to 93 : 7. Several transformations were performed to demonstrate the synthetic potential of these α,α-difluoro-β-hydroxy ketones. In addition, this method has been extended to the use of other electrophiles such as imines and chalcogen derivatives, and a difluoromethyl sulfoxide as nucleophile, thus leading to a diversity of difluoromethylene compounds. 相似文献
104.
105.
Amílcar Pacheco 《代数通讯》2013,41(11):3689-3703
106.
Vázquez-Olmos A Redón R Rodríguez-Gattorno G Esther Mata-Zamora M Morales-Leal F Fernández-Osorio AL Saniger JM 《Journal of colloid and interface science》2005,291(1):175-180
One-step room-temperature synthesis of nanocrystalline Mn3O4 hausmannite, without heating posttreatment, was carried out from a simple dissolution of manganese(II) acetate in a mixture of N,N'-dimethylformamide (DMF) and water. Homogeneous nanocrystals like rods were obtained, with an average width and length of 6.6+/-1.2 nm and 17.4+/-4.1 nm, respectively, and a preferential growth along the 001 direction. Magnetization measurements on a powdered sample showed ferrimagnetic behavior at low temperatures. Under zero-field cooling (ZFC) measurement at 100 Oe, the observed blocking temperature (T(B)) was 37 K. 相似文献
107.
Hayriye Nevin Genc Abdulkadir Sirit 《Journal of inclusion phenomena and macrocyclic chemistry》2018,90(1-2):39-49
New bifunctional calixarene thiourea organocatalysts were synthesized and applied in catalytic asymmetric Michael addition of acetylacetone to various nitroolefins at room temperature. The corresponding adducts were obtained in good to excellent yields with excellent enantioselectivities (up to 92% ee). The present research demonstrates the advantages of incorporating two stereocontrolling structures into a single catalyst. Notably, it offers a simple and convenient doubly stereocontrolled approach for the catalytic asymmetric synthesis of a chiral organic molecule. 相似文献
108.
The action modes of Lippia sidoides (Cham) essential oil as penetration enhancers on snake skin 总被引:1,自引:0,他引:1
M. B. Brito Gabriela B. Barin A. A. S. Araújo D. P. de Sousa S. C. H. Cavalcanti Ana Amélia M. Lira Rogéria S. Nunes 《Journal of Thermal Analysis and Calorimetry》2009,97(1):323-327
The aim of this work was to study the effect of Lippia sidoides essential oil (LSEO) on stratum corneum lipids and the permeation of salicylic acid. DSC and FTIR spectroscopy were applied.
LSEO 1% (v/v) significantly enhanced salicylic acid flux through snake skin. According to the DSC curves changes in the transition
temperature of the lipids were observed indicating that LSEO can interact with stratum corneum. The IR spectrum of skin treated
with LSEO showed a decrease in the peak intensity for CH2 stretchings (2920–2850 cm–1) however the peak positions did not alter suggesting the extraction of the lipids. 相似文献
109.
We give a Taylor series expansion for the joint Laplace transform of stationary waiting times in open (max,+)-linear stochastic systems with Poisson input. Probabilistic expressions are derived for coefficients of all orders. Even though the computation of these coefficients can be hard for certain systems, it is sufficient to compute only a few coefficients to obtain good approximations (especially under the assumption of light traffic). Combining this new result with the earlier expansion formula for the mean stationary waiting times, we also provide a Taylor series expansion for the covariance of stationary waiting times in such systems.It is well known that (max,+)-linear systems can be used to represent stochastic Petri nets belonging to the class of event graphs. This class contains various instances of queueing networks like acyclic or cyclic fork-and-join queueing networks, finite or infinite capacity tandem queueing networks with various types of blocking, synchronized queueing networks and so on. It also contains some basic manufacturing models such as kanban networks, assembly systems and so forth. The applicability of this expansion technique is discussed for several systems of this type. 相似文献
110.
Kenan Aydogan Serkan Yazici Saduman Balaban Adim Ferah Budak Hayriye Saricaoglu Sukran Tunali Emel Bulbul Baskan 《Photochemistry and photobiology》2014,90(4):873-877
Mycosis fungoides (MF) and parapsoriasis (PP) are major dermatologic conditions for which phototherapy continues to be a successful and valuable treatment option. UVA‐1 phototherapy is effective in the management of cutaneous T‐cell mediated diseases. The aim of the study was to evaluate the efficacy and safety of low‐dose UVA‐1 phototherapy for the management of PP/early‐stage MF. A total of 30 patients, diagnosed with MF (n:19) or PP (n:11) were enrolled to the study. All patients were managed with low‐dose UVA‐1 (20 or 30 J cm?2). Response was assessed clinically and immunohistochemically. UVA‐1 treatment led to clinical and histological complete remission (CR) in 11 of 19 MF patients (57.9%), partial remission (PR) in three of 19 (15.8%), after a mean cumulative dose of 1665 (range, 860–3120) J cm?2 and mean number of 73 exposure (range, 43–107) sessions. Five patients with PP (45.5%) showed CR, and PR was observed in six patients with PP (54.5%) after a mean cumulative dose of 1723 (range, 1060–3030) J cm?2 and mean number of 74 exposure (range, 53–101) sessions. We conclude that low‐dose UVA‐1 therapy seems to be an effective, safe, and well‐tolerated treatment option for patients with PP/early‐stage MF. 相似文献