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201.
Ksenia V. Ksenofontova Anastasia A. Kerner Alexander A. Ksenofontov Artyom Yu. Shagurin Pavel S. Bocharov Michael M. Lukanov Airat R. Kayumov Darya E. Zhuravleva Zalina I. Iskhakova Evgeniy E. Molchanov Dmitriy A. Merkushev Ilya A. Khodov Yuriy S. Marfin 《Molecules (Basel, Switzerland)》2022,27(22)
A boron-dipyrromethene (BODIPY) derivative reactive towards amino groups of proteins (NHS-Ph-BODIPY) was synthesized. Spectroscopic and photophysical properties of amine-reactive NHS-Ph-BODIPY and its non-reactive precursor (COOH-Ph-BODIPY) in a number of organic solvents were investigated. Both fluorescent dyes were characterized by green absorption (521–532 nm) and fluorescence (538–552 nm) and medium molar absorption coefficients (46,500–118,500 M−1·cm−1) and fluorescence quantum yields (0.32 – 0.73). Solvent polarizability and dipolarity were found to play a crucial role in solvent effects on COOH-Ph-BODIPY and NHS-Ph-BODIPY absorption and emission bands maxima. Quantum-chemical calculations were used to show why solvent polarizability and dipolarity are important as well as to understand how the nature of the substituent affects spectroscopic properties of the fluorescent dyes. NHS-Ph-BODIPY was used for fluorescent labeling of a number of proteins. Conjugation of NHS-Ph-BODIPY with bovine serum albumin (BSA) resulted in bathochromic shifts of absorption and emission bands and noticeable fluorescence quenching (about 1.5 times). It was demonstrated that the sensitivity of BSA detection with NHS-Ph-BODIPY was up to eight times higher than with Coomassie brilliant blue while the sensitivity of PII-like protein PotN (PotN) detection with NHS-Ph-BODIPY and Coomassie brilliant blue was almost the same. On the basis of the molecular docking results, the most probable binding sites of NHS-Ph-BODIPY in BSA and PotN and the corresponding binding free energies were estimated. 相似文献
202.
The problem of obtaining the matrix elements of Hartree-Fock Hamiltonians for alkanes using the EO method is considered. It has been shown that the data on the electronic structure of diamond together witht 1/e splitting in the neopentane photoelectron spectrum are helpful to produce such EO method parameter scale which involves even “through space” interactions. In terms of the EO method the photoelectron spectra of propane, butane, isobutane, and neopentane are interpreted. The valence band structure of polyethylene in analytical form is obtained. 相似文献
203.
St'astný V Stibor I Císarová I Sýkora J Pojarová M Lhoták P 《The Journal of organic chemistry》2006,71(14):5404-5406
A novel type of doubly bridged thiacalix[4]arenes in the 1,3-alternate conformation has been prepared by direct aminolysis reaction of easily accessible thiacalix[4]arene tetraacetates with alpha,omega-diamines. Despite the high excess of diamine, both sites of a 1,3-alternate conformer can be intramolecularly bridged to form the cagelike structures in high yields. Optimum results were obtained using 1,2-ethanediamine as bridging units. X-ray analysis of the novel cagelike molecules revealed a highly preorganized array of -C(O)-NH- bonds pointing to the interior of the cavity. 相似文献
204.
Afanasiev P 《Inorganic chemistry》2002,41(21):5317-5319
Dispersed Mo(2)N with lamellar morphology and high specific surface area was obtained from the decomposition of the (HMT)(2)(NH(4))(4)Mo(7)O(24) salt (HMT = hexamethylentertramine) in the temperature range 550-800 degrees C. During the thermal decomposition, reduction of Mo species by carbon from the HMT ligand occurs, with release of CO gas. 相似文献
205.
Contactless conductivity detection is successfully demonstrated for the enantiomeric separation of basic drugs and amino acids in capillary electrophoresis (CE). Derivatization of the compounds or the addition of a visualization agent as for indirect optical detection schemes were not needed. Non-charged chiral selectors were employed, hydroxypropylated cyclodextrin (CD) for the more lipophilic basic drugs and 18-crown-6-tetracarboxylic acid (18C6H4) for the amino acids. Acidic buffer solutions based on lactic or citric acid were used. The detection limits were determined as 0.3 microM for pseudoephedrine as an example of a basic drug and were in the range from 2.5 to 20 microM for the amino acids. 相似文献
206.
Yuriy A. Zhabanov Alexey V. Eroshin Igor V. Ryzhov Ilya A. Kuzmin Daniil N. Finogenov Pavel A. Stuzhin 《Molecules (Basel, Switzerland)》2021,26(10)
The Knudsen effusion method with mass spectrometric control of the vapor composition was used to study the possibility of a congruent transition to the gas phase and to estimate the enthalpy of sublimation of metal-free tetrakis(1,2,5-thiadiazolo)porphyrazine and its nickel complex (H2TTDPz and NiTTDPz, respectively). The geometrical and electronic structure of H2TTDPz and NiTTDPz in ground and low-lying excited electronic states were determined by DFT calculations. The electronic structure of NiTTDPz was studied by the complete active space (CASSCF) method, following accounting dynamic correlation by multiconfigurational quasi-degenerate second-order perturbation theory (MCQDPT2). A geometrical structure of D2h and D4h symmetry was obtained for H2TTDPz and NiTTDPz, respectively. According to data obtained by the MCQDPT2 method, the nickel complex possesses the ground state 1A1g, and the wave function of the ground state has the form of a single determinant. Electronic absorption and vibrational (IR and resonance Raman) spectra of H2TTDPz and NiTTDPz were studied experimentally and simulated theoretically. 相似文献
207.
Wang Z Palacios MA Zyryanov G Anzenbacher P 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(28):8540-8546
Ratiometric fluorescence-based sensors are widely sought after because they can effectively convert even relatively small changes in optical output into a strong and easy-to-read signal. However, ratiometric sensor molecules are usually difficult to make. We present a proof-of-principle experiment that shows that efficient ratiometric sensing may be achieved by an array of two chromophores, one providing an on-to-off response and the second yielding an off-to-on response in a complementary fashion. In the case that both chromophores emit light of different color, the result is a switching of colors that may be utilized in the same way as from a true ratiometric probe. The chromophore array comprises two sensor elements: i) a polyurethane membrane with embedded N-anthracen-9-yl-methyl-N-7-nitrobenzoxa-[1,2,5]diazo-4-yl-N',N'-dimethylethylenediamine hydrochloride and ii) a membrane with N,N-dimethyl-N'-(9-methylanthracenyl)ethylenediamine. A combination of photoinduced electron transfer (PET) and fluorescence resonance energy transfer (FRET) allows for green-to-blue emission switching in the presence of Zn(II) ions. The sensing experiments carried out with different Zn(II) salts at controlled pH revealed that the degree of color switching in the individual sensor elements depends on both the presence of Zn(II) ions and the counter anion. These results suggest that sensing of both cations and anions may perhaps be extended to different cation-anion pairs. 相似文献
208.
The tryptophyl-glycine (Trp-Gly) and tryptophyl-glycyl-glycine (Trp-Gly-Gly) peptides have been studied by means of molecular dynamic simulations combined with high-level correlated ab initio quantum chemical and statistical thermodynamic calculations. The lowest energy conformers were localized in the free energy surface. The structures of the different Trp-Gly and Trp-Gly-Gly conformers coexisting in the gas phase have been for the first time reported and their scaled theoretical IR spectra unambiguously assigned and compared with previous gas-phase experimental results. Common geometrical features have been systematically observed for the sequence Trp, Trp-Gly, and Trp-Gly-Gly. In addition, the peptide backbone of Trp-Gly-Gly has been compared with that of the previously studied Phe-Gly-Gly (Reha, D. et. al. Chem. Eur. J. 2005, 11, 6803). From the observed systematic structural behavior between these peptide analogues, it is expected that the gas-phase conformers of other similar aromatic small peptides would present equivalent geometries. The DFT methodology failed to describe the potential energy surface of the studied peptides since the London dispersion energy (not covered in DFT) plays a significant role in the stabilization of most stable conformers. 相似文献
209.
Summary In the first part of this paper we are dealing with theoretical statements and conditions which lead to existence and uniqueness of the solution of a nonlinear boundary value problem with delay. Next we apply this method successfully to a numerical example. The computations have been carried out at the computer Siemens 4004. The data obtained are presented in two tables. 相似文献
210.
Varghese HT Panicker CY Philip D Pazdera P 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,67(3-4):1055-1059
FT-Raman and FT-IR spectra of 2-cyanophenylisocyanid dichloride were recorded and analyzed. The vibrational frequencies of the title compound have been computed using the Hartree-Fock/6-31G* basis and compared with the experimental values. The prepared compound was identified by NMR and mass spectra. 相似文献