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991.
Kádár Z Kovács D Frank É Schneider G Huber J Zupkó I Bartók T Wölfling J 《Molecules (Basel, Switzerland)》2011,16(6):4786-4806
A straightforward and reliable method for the regioselective synthesis of steroidal 1,4-disubstituted triazoles and 1,5-disubstituted tetrazoles via copper(I)-catalyzed cycloadditions is reported. Heterocycle moieties were efficiently introduced onto the starting azide compound 3β-acetoxy-16β-azidomethylandrost-5-en-17β-ol through use of the "click" chemistry approach. The antiproliferative activities of the newly-synthesized triazoles were determined in vitro on three human gynecological cell lines (HeLa, MCF7 and A2780) using the microculture tetrazolium assay. 相似文献
992.
Louërat F Tye H Napier S Garrigou M Whittaker M Gros PC 《Organic & biomolecular chemistry》2011,9(6):1768-1773
The concomitant use of silver oxide and catalytic amount of TBAF allowed the efficient and chemoselective coupling of readily available 4-chloro- and 4-methyl-2-trimethyl-silyl-pyridines with heteroaromatic and aromatic halides. Based on control experiments, a mechanism involving the formation of a pyridylsilver intermediate and TBAF recycling is postulated. 相似文献
993.
Kádár Z Baji Á Zupkó I Bartók T Wölfling J Frank É 《Organic & biomolecular chemistry》2011,9(23):8051-8057
Stereoselective 1,4-Michael addition of azoimide to 17β-acetoxy-5α-adrost-1-en-3-one was carried out to furnish a 1α-azido-3-ketone, which was reduced to give the 3β- and 3α-hydroxy epimers in a ratio of 5 : 2. The Cu(I)-catalyzed 1,3-dipolar cycloaddition of the major isomer to terminal alkynes afforded 1α-triazolyl derivatives, which were deacetylated to the corresponding 3β,17β-diols or oxidized to the analogous 3-ketones. However, the ability of the minor 1α,3α-azidoalcohol to undergo similar cyclization was found to be affected significantly by the steric bulk of the substituents on the alkyne reaction partner. All triazolyl compounds were tested in vitro on three malignant gynecological cell lines (HeLa, MCF7 and A2780). 相似文献
994.
Molnár A Kapros A Párkányi L Mucsi Z Vlád G Hermecz I 《Organic & biomolecular chemistry》2011,9(19):6559-6565
The palladium-catalyzed Suzuki-Miyaura cross-coupling reactions of halo derivatives of 4H-pyrido[1,2-a]pyrimidin-4-one with (het)arylboronic acids allow easy access to (het)aryl and vinyl derivatives of this bicycle in good to excellent yields, even from chloro derivatives. The sequence of reactivity of the halogen in the different positions of the ring system was also investigated. 6-Phenyl-4H-pyrido[1,2-a]pyrimidin-4-one could be prepared by thermal cyclization of isopropylidene (6-phenylpyrid-2-ylamino)methylenemalonate, together with a small amount of 7-phenyl-1,4-dihydro-1,8-naphthyridin-4-one. 相似文献
995.
Dinda J Liatard S Chauvin J Jouvenot D Loiseau F 《Dalton transactions (Cambridge, England : 2003)》2011,40(14):3683-3688
This work describes the synthesis and characterization of two new bis-terdentate Ru(II) complexes. Compound 1 is a homoleptic complex containing two CNC N-heterocyclic carbene (NHC) based ligands, whereas compound 2 bears one CNC ligand and an ancillary terpyridine ligand. The redox and photophysical properties of both compounds have been investigated and their X-ray crystal structures determined. Complex 1 displays a close-to-perfect octahedral coordination geometry and is not luminescent at room temperature while complex 2 features room temperature and 77 K luminescence despite its partially distorted geometry. The presence of the NHC moieties brings a significant amount of electronic density to the metal centre therefore lowering its oxidation potential with respect to that of analogous polypyridyl complexes. 相似文献
996.
Murtaza G Badshah A Said M Khan H Khan A Khan S Siddiq S Choudhary MI Boudreau J Fontaine FG 《Dalton transactions (Cambridge, England : 2003)》2011,40(36):9202-9211
A series of N,N',N'-trisubstituted guanidines (1-6) and their copper(II) complexes, [κ(2)(O,N)-C(6)H(5)CONHC(NHC(6)H(4)Cl)NR](2)Cu(ii) (R = iso-propyl (1a), n-butyl (2a), sec-butyl (3a), tert-butyl (4a), benzyl (5a), and para-tolyl (6a)) were synthesized and characterized using elemental analysis, FTIR and NMR spectroscopy. DFT studies were used to assess the location of the protons in the free ligands. However, calculations have shown that, in all cases, hydrogen bonding from either N-H group gives conformations that are very similar in energy. Single crystal XRD studies were used to characterize ligands 1 and 4 and the related complexes 1a and 4a. The structures reveal that these complexes are mononuclear in the solid state and that copper adopts a regular square planar geometry. In both metallic species, the N, N', N'-trisubstituted guanidine ligands chelate the Cu(II) atom using the oxygen and one nitrogen. The synthesized compounds were investigated for urease inhibition using thiourea as a standard drug. Most complexes exhibit a better activity than the respective guanidines and compound 1a was found to be the most active with IC(50) = 9.83 ± 0.07 μM (the IC(50) for thiourea is 21.0 ± 0.1 μM). The species were also screened for their anti-leishmanial activity. However, all of the compounds were devoid of any significant activity. 相似文献
997.
A general and convenient protocol for the electrophilic borylation of aryl Grignard reagents prepared from arylbromides by direct insertion of magnesium in the presence of LiCl or by Mg/Br exchange with (i)PrMgCl·LiCl has been developed. Various aryl boronic acids were synthesized in a straightforward manner in excellent yields at 0 °C. 相似文献
998.
Two ordinary green light-emitting diodes used as light emitter and detector coupled with simple voltmeter form a complete,
cost-effective prototype of a photometric hemoglobinometer. The device has been optimized for cuvette assays of total hemoglobin
(Hb) in diluted blood using three different chemical methods recommended for the needs of clinical analysis (namely Drabkin,
lauryl sulfate, and dithionite methods). The utility of developed device for real analytics has been validated by the assays
of total Hb content in human blood. The results of analysis are fully compatible with those obtained using clinically recommended
method and clinical analyzer. 相似文献
999.
Frédéric Bernicot 《Mathematische Annalen》2011,351(1):1-49
In this work, we study some non-smooth bilinear analogues of linear Littlewood–Paley square functions on the real line. We prove boundedness-properties in Lebesgue spaces for them. Let us consider the functions \({\phi_{n}}\) satisfying \({\widehat{\phi_n}(\xi)={\bf 1}_{[n,n+1]}(\xi)}\) and define the bilinear operator \({S_n(f,g)(x):=\int f(x+y)g(x-y) \phi_n(y) dy}\) . These bilinear operators are closely related to the bilinear Hilbert transforms. Then for exponents \({p,q,r'\in[2,\infty)}\) satisfying \({\frac{1}{p}+\frac{1}{q}=\frac{1}{r}}\) , we prove that
相似文献
$\left\| \left( \sum_{n\in \mathbb{Z}}\left|S_n(f,g) \right|^2 \right)^{1/2}\right\|_{L^{r}(\mathbb{R})}\lesssim \|f\|_{L^p(\mathbb{R})}\|g\|_{L^q(\mathbb{R})}.$
1000.
Samira El Moumen Rachid EllaiaRajae Aboulaich 《Applied mathematics and computation》2011,218(7):3265-3276
In this paper we present a new hybrid method, called the SASP method. The purpose of this method is the hybridization of the simulated annealing (SA) with the descent method, where we estimate the gradient using simultaneous perturbation. Firstly, the new hybrid method finds a local minimum using the descent method, then SA is executed in order to escape from the currently discovered local minimum to a better one, from which the descent method restarts a new local search, and so on until convergence.The new hybrid method can be widely applied to a class of global optimization problems for continuous functions with constraints. Experiments on 30 benchmark functions, including high dimensional functions, show that the new method is able to find near optimal solutions efficiently. In addition, its performance as a viable optimization method is demonstrated by comparing it with other existing algorithms. Numerical results improve the robustness and efficiency of the method presented. 相似文献