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991.
Bénédicte DelouvriéHervé Germain Craig S. Harris Maryannick LamorletteHonorine Lebraud Ha Thi Hoang NguyenAnais Noisier Gilles Ouvry 《Tetrahedron letters》2012,53(40):5380-5384
During our efforts to selectively synthesise N-arylated benzotriazole fragments, we developed a new primary aromatic amine protecting group strategy showing significant advantages over recognised protecting groups. 相似文献
992.
Karthikeyan Gunasekaran Thi H. Nguyen Heather D. Maynard Thomas P. Davis Volga Bulmus 《Macromolecular rapid communications》2011,32(8):654-659
A thiol‐modified siRNA targeting the enhanced green fluorescence protein (eGFP) gene was conjugated with RAFT‐synthesized, pyridyl disulfide‐functional poly(PEG methyl ether acrylate)s (p(PEGA)s). siRNA‐p(PEGA) conjugates demonstrated significantly enhanced in vitro serum stability and nuclease resistance compared to the unmodified and thiol‐modified siRNA. The complexes of siRNA‐p(PEGA) conjugates with a fusogenic peptide, KALA ((+)/(–) = 2) inhibited the protein expression approximately 28‐fold more than the KALA complex of the unmodified siRNA. The protein inhibition caused by siRNA‐p(PEGA)‐KALA complexes (56 ± 5%–58 ± 3% of the fluorescence expressed in non‐treated cells) was comparable to the effect of the unmodified siRNA‐lipofectamine complex (77 ± 7%).
993.
Marini RD Groom C Doucet FR Hawari J Bitar Y Holzgrabe U Gotti R Schappler J Rudaz S Veuthey JL Mol R Somsen GW de Jong GJ Ha PT Zhang J Van Schepdael A Hoogmartens J Briône W Ceccato A Boulanger B Mangelings D Vander Heyden Y Van Ael W Jimidar I Pedrini M Servais AC Fillet M Crommen J Rozet E Hubert P 《Electrophoresis》2006,27(12):2386-2399
994.
Sayle DC Mangili BC Klinowski J Sayle TX 《Journal of the American Chemical Society》2006,128(47):15283-15291
Characterization of materials is crucial for the quantification and prediction of their physical, chemical, and mechanical properties. However, as the complexity of a system increases, so do the challenges involved in elucidating its structure. While molecular simulation and modeling have proved invaluable as complements to experiment, such simulations now face serious challenges: new materials are being synthesized with ever increasing structural complexity, and it may soon prove impossible to generate models that are sufficiently realistic to describe them adequately. Perhaps, ultimately, it will only be possible to generate such models by simulating the synthetic process itself. Here, we attempt such a strategy to generate full atomistic models for mesoporous molecular sieves. As in experiment, this is done by allowing nanoparticles to self-assemble at high temperature to form an amorphous mesoporous framework. The temperature is then reduced, and the system is allowed to crystallize. Animations of atomic trajectories, available as Supporting Information, reveal the evolution of multiple seeds which propagate to form a complex framework. The products are polycrystalline mesoporous framework structures containing cavities connected by channels running along "zero", one, two, and three perpendicular directions. We suggest that it is easier to generate these model structures by attempting to simulate the synthetic process rather than by using more conventional techniques. The strategy is illustrated using ZnS as a model system. Further development of the mathematics of minimal surfaces will advance our understanding of these structures. 相似文献
995.
Thiébaut D Vial J Michel M Hennion MC Greibrokk T 《Journal of chromatography. A》2006,1122(1-2):97-104
Quantification of neurotransmitters as biologically active analytes in neurological samples is of high interest for studying their effect on multiple targets. This work is part of a strategy involving two-dimensional liquid chromatography (2D LC) system with mass spectrometry (MS) detection. The concept of the on-line LC system is the coupling of reversed phase liquid chromatography (RPLC, the second separation dimension) to ion-exchange chromatography (IEC, the first dimension). Our objective in this study is to find the appropriate second dimension column, ensuring that samples of neurotransmitters are refocused and separated on it. Silica-based columns designed specifically to retain polar compounds were tested in LC conditions and compared with results obtained with a porous graphitic carbon (PGC, Hypercarb) column. These polar embedded, polar endcapped, and high-density alkyl chain columns successfully separated analytes in question using mobile phase systems with high percentage of water, or even pure water. Only Hypercarb column provided efficient retention of the most polar neurotransmitters and could be used for trapping and preconcentrating the compounds without rapid breakthrough. 相似文献
996.
Truong Thi Ngoc Lien Vu Thi Hong An Duong Tuan Quang Dinh Quang Khieu Young Hoon Lee 《Talanta》2010,80(3):1164-2580
In this paper, we describe DNA electrochemical detection for genetically modified organism (GMO) based on multi-wall carbon nanotubes (MWCNTs)-doped polypyrrole (PPy). DNA hybridization is studied by quartz crystal microbalance (QCM) and electrochemical impedance spectroscopy (EIS). An increase in DNA complementary target concentration results in a decrease in the faradic charge transfer resistance (Rct) and signifying “signal-on” behavior of MWCNTs-PPy-DNA system. QCM and EIS data indicated that the electroanalytical MWCNTs-PPy films were highly sensitive (as low as 4 pM of target can be detected with QCM technique). In principle, this system can be suitable not only for DNA but also for protein biosensor construction. 相似文献
997.
Tran Duc Thiep Truong Thi An Nguyen Tuan Khai Nguyen The Vinh Phan Viet Cuong I. P. Gangrski I. E. Penhionzkevich G. V. Mishinski V. I. Zemenhik 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(3):511-517
The ratio of the probabilities of population of the isomeric and ground states, so called the isomeric ratio is closely connected to the angular momentum of the initial fission fragments that is dissipated at the later stages of gamma ray cascade. This ratio also provides important information on the nuclear level structure as well as the nuclear reaction mechanism involved. In this work, the isomeric ratio in fission fragment 135Xe from photofission of 233U induced by 23.5 MeV bremsstrahlung has been determined by the method that uses inert gaseous flow. The results have been discussed and compared with that of other authors. 相似文献
998.
Le Thi Phuong Ngoc Le Khanh Luan Tran Minh Thuyet Nguyen Thanh Long 《Nonlinear Analysis: Theory, Methods & Applications》2009,71(11):5799-5819
In this paper, we consider the following nonlinear wave equation (1) where , , μ, f, g are given functions. To problem (1), we associate a linear recursive scheme for which the existence of a local and unique weak solution is proved by applying the Faedo–Galerkin method and the weak compact method. In the case of , , μ(z)≥μ0>0, μ1(z)≥0, for all , and , , , a weak solution uε1,ε2(x,t) having an asymptotic expansion of order N+1 in two small parameters ε1, ε2 is established for the following equation associated to (1)2,3: (2) 相似文献
999.
In this paper, we address the global optimization of functions subject to bound and linear constraints without using derivatives
of the objective function. We investigate the use of derivative-free models based on radial basis functions (RBFs) in the
search step of direct-search methods of directional type. We also study the application of algorithms based on difference
of convex (d.c.) functions programming to solve the resulting subproblems which consist of the minimization of the RBF models
subject to simple bounds on the variables. Extensive numerical results are reported with a test set of bound and linearly
constrained problems. 相似文献
1000.
Tran Thi Viet NgaNguyen Phuc Duong Than Duc Hien 《Journal of magnetism and magnetic materials》2012,324(6):1141-1146
Ultrafine aluminum-substituted strontium hexaferrite particles have been prepared via citrate sol-gel route. Gels were synthesized with molar ratios [Al3+]:[Fe3+] of 0.4:11.6, 1:11, 1.5:10.5 and 2:10 and the ferrite particles were obtained by annealing the gels at 950 °C for 2 and 24 h. Electron energy dispersive X-ray spectroscopy (EDX) verified the presence of Al in the substituted samples. X-ray diffraction (XRD) confirmed the formation of the M-type hexaferrite phase in the samples with some indication of α-Fe2O3. Scanning electron microscope showed that the hexaferrite powder consists hexagonal crystals with average diameter Dav (80-186 nm) that decreases with increasing Al content and increases with increasing annealing time. Magnetic properties were determined using a pulsed-field magnetometer and a vibrating sample magnetometer (VSM). The saturation magnetization at room temperature and the Curie temperature were found to decrease while the coercivity increases with increasing the Al content. The highest coercivity of 10.1 kOe was achieved for the sample with the molar ratio [Al3+]:[Fe3+]=2:10 annealed for 24 h. The influences of the particle size, composition and impurity on the magnetic properties were discussed. 相似文献