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161.
《Macromolecular bioscience》2017,17(12)
Chondrocytes are important for cartilage tissue engineering. However, dedifferentiation during chondrocyte subculture prevents the application of cartilage tissue engineering. Therefore, prevention of this dedifferentiation is required. Here, the possibility of poly(2‐methoxyethyl acrylate) (PMEA) and its analogous polymers, poly(tetrahydrofurfuryl acrylate) (PTHFA) and poly(2‐(2‐methoxyethoxy) ethyl acrylate‐co‐butyl acrylate) (PMe2A), for chondrocyte subculture without dedifferentiation is examined. Chondrocytes spread on PTHFA and polyethylene terephthalate (PET), whereas their spreading is delayed on PMEA and PMe2A. When primary chondrocytes are subcultured on these polymers, the expression levels of cartilaginous genes are higher on PMEA and PMe2A than on PET and PTHFA. Integrin contribution to the initial cell adhesion is lower on PMEA and PMe2A than on PTHFA and PET. This low level of integrin contribution to cell adhesion may cause a delay in cell spreading and the maintenance of cartilaginous gene expression. These results indicate that PMEA and PMe2A may be favorable substrates for chondrocyte subculture and cartilage tissue engineering. 相似文献
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163.
Wladyslaw Reimschüssel Halina Abramczyk Jacek Michalak 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):201-211
Abstract 2-Chloro-5,5-dimethyl-2-oxo-1,3,2-dioxaphosphorinane has been studied in CCl4, CHCl3 and CD3CN solutions by IR and Raman line shape analysis. Equilibrium process of dimerization and ring conversion in CCl4 solutions have been considered. On the contrary to the commonly expected dominance of the conformer with the equatorial oriented P[dbnd]O bond for 2-halo-2-oxo-1,3,2-dioxaphosphorinanes, it was found that for the 2-chloro derivative both conformers are nearly equally distributed. It has been shown that the interactions induced absorption is an important mechanism of relaxation in the studied compound and this mechanism gives significant contribution to the total IR band broadening, while the interaction induced light scattering is negligible. The obtained results show that the molecular dynamics method can be useful in studying cyclic compounds in solutions. 相似文献
164.
The analysis on the recovery performance and characteristics in shape memory effects is helpful for the optimal design and engineering applications of shape memory polymers and their composites. To investigate the relationships among recovery performance, material parameters, and loading conditions, by taking aliphatic polyether urethane as an example, the researchers simulate the shape memory behaviors numerically using a three‐dimensional viscoelastic model. The material parameters for this model are taken from stress relaxation tests, rather than dynamic mechanical analysis tests. Both the unconstrained and the constrained recovery behaviors during strain‐controlled shape memory processes are analyzed. The results reveal that the unconstrained recovery occurs at the same temperature regardless of the applied strain values. Another interesting result is that the shape recovery temperature in unconstrained recovery situations increases and the maximum recovery stress under constrained recovery conditions decreases with the increase of heating rates. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
165.
Hossein Reza Darabi Abbas Darestani Farahani Mohammad Hashemi Karouei Kioumars Aghapoor Rohoullah Firouzi Rainer Herges 《Supramolecular chemistry》2013,25(9):653-657
A new E,E-stilbenophane was synthesised and characterised. The crystal structure of this cyclophane shows that this molecule has a cup-shaped structure, which hosts a phenyl ring of neighbouring molecule as guest in its cavity with a π–π distance of about 3.7 Å. Moreover, the NMR spectra and theoretical analysis (gauge-independent atomic orbitals (GIAO) and quantum theory of atoms in molecules (QTAIM)) suggest that the silver recognition by E,E-stilbenophane host molecules is based on cation–π interactions in which the π-electrons of the double bonds play a major role. 相似文献
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167.
以乙二醇、乙醇为溶剂通过溶剂热法制备出立方状ITO纳米粉体,研究了反应时间、NaOH浓度对ITO纳米粉体形貌的影响,并讨论了溶剂体积比、NaOH浓度对ITO粉体导电性的影响及机理。结果表明:采用乙二醇与乙醇做溶剂,VEG:VEtOH=4:1时,制备出分散性良好的立方状ITO纳米粉体,平均粒径为10.7 nm,且其XRD衍射峰强度比I400/I222最高为0.380;乙二醇与乙醇做溶剂,VEG:VEtOH=4:1,且NaOH浓度为0.275 mol·L-1时,粉体电导率最高为46.75 mS·cm-1。 相似文献
168.
Being able to predict the final product yield at all stages in long-running, industrial, mammalian cell culture processes is vital for both operational efficiency, process consistency, and the implementation of quality by design (QbD) practices. Here we used Raman spectroscopy to monitor (in terms of glycoprotein yield prediction) a fed-batch fermentation from start to finish. Raman data were collected from 12 different time points in a Chinese hamster ovary (CHO) based manufacturing process and across 37 separate production runs. The samples comprised of clarified bioprocess broths extracted from the CHO cell based process with varying amounts of fresh and spent cell culture media. Competitive adaptive reweighted sampling (CoAdReS) and ant colony optimization (ACO) variable selection methods were used to enhance the predictive ability of the chemometric models by removing unnecessary spectral information. Using CoAdReS accurate prediction models (relative error of predictions between 2.1% and 3.3%) were built for the final glycoprotein yield at every stage of the bioprocess from small scale up to the final 5000 L bioreactor. This result reinforces our previous studies which indicate that media quality is one of the most significant factors determining the efficiency of industrial CHO-cell processes. This Raman based approach could thus be used to manage production in terms of selecting which small scale batches are progressed to large-scale manufacture, thus improving process efficiency significantly. 相似文献
169.
Martin Schmid Hans‐Peter Steinrück J. Michael Gottfried 《Surface and interface analysis : SIA》2014,46(8):505-511
Asymmetric peak profiles for the application in spectroscopy can be obtained in a simple way by substituting the usually constant full width at half maximum parameter in Pseudo‐Voigt functions with an energy‐dependent expression, for instance of sigmoidal shape. While this approach has been successfully applied to vibrational spectra, we find that the resulting curves are less suitable for least‐squares fits of X‐ray photoelectron spectroscopy (XPS) data. However, if one additionally allows a variable displacement of the sigmoidal step relative to the peak, excellent fitting results can be obtained. We demonstrate the applicability of our extended approach on several inherently asymmetric XPS lines, i.e. the C 1s signal of graphite and C2H2/Pd(100), the 3d5/2–3d3/2 doublet of palladium, and the 4f7/2–4f5/2 doublet of platinum. Comparison of the corresponding fit results with the results obtained by the application of more elaborate, theory‐based line profiles (Doniach‐?unji? and Mahan functions) shows that the modified Pseudo‐Voigt function gives practically identical results in terms of peak shape and area, while requiring much less computational effort since no convolution procedures are required for its calculation. Thus, this function is most suitable for application in one of the following situations: (i) the peak shape of a given signal is known but cannot be calculated with ease, and (ii) the theoretical peak shape is not (yet) known, however, one wants to perform a first quantitative screening of the data at issue. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
170.
On the induced‐fit mechanism of substrate‐enzyme binding structures of nylon‐oligomer hydrolase 下载免费PDF全文
Takeshi Baba Ryuhei Harada Masayoshi Nakano Yasuteru Shigeta 《Journal of computational chemistry》2014,35(16):1240-1247
We present a detailed computational investigation of the induced‐fit motion in a nylon‐oligomer hydrolase (NylB) upon substrate binding. To this aim, we resort on the recently introduced parallel cascade selection molecular dynamics approach, allowing for an accelerated access to the set of conformational changes from an open‐ to a closed‐state structure to form the enzyme‐substrate complex in a specific induce‐fit mechanism. The structural investigation is quantitatively complemented by free energy analyses within the umbrella sampling algorithm accompanied by weighted histogram analysis. We find that the stabilization free energy is about 1.4 kcal/mol, whereas the highest free energy barrier to be overcome is about 2.3 kcal/mol. Conversely, the energetic contribution for the substrate binding is about 20 kcal/mol, as estimated from Generalized Born/Surface Area. This means that the open‐close induced‐fit motion could occur frequently once the substrate binds to the open state of NylB. © 2014 Wiley Periodicals, Inc. 相似文献