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971.
Experimental evaluation of the transesterification of waste palm oil into biodiesel 总被引:43,自引:0,他引:43
Transesterified vegetable oils (VOs) are promising alternative diesel fuel. Waste VOs are cheap and renewable but currently disposed of inadequately. In this work, waste palm oil was transesterified under various conditions. H2SO4 and different concentrations of HCl and ethanol at different excess levels were used. Higher catalyst concentrations (1.5-2.25 M) produced biodiesel with lower specific gravity, gamma, in a much shorter reaction time than lower concentrations. The H2SO4 performed better than HCl at 2.25 M, as it resulted in lower gamma. Moreover, a 100% excess alcohol effected significant reductions in reaction time and lower gamma relative to lower excess levels. The best process combination was 2.25 M H2SO4 with 100% excess ethanol which reduced gamma from an initial value of 0.916 to a final value of 0.8737 in about 3 h of reaction time. Biodiesel had the behavior of a Newtonian fluid. 相似文献
972.
973.
974.
Background
Existing cut-offs for fasting plasma glucose (FPG) and post-load glucose (2hPG) criteria are not equivalent in the diagnosis of diabetes and glucose intolerance. Adjusting cut-offs of single measurements have not helped so we undertook this project to see if they could be complementary. 相似文献975.
Chohan ZH Iqbal MS Iqbal HS Scozzafava A Supuran CT 《Journal of enzyme inhibition and medicinal chemistry》2002,17(2):87-91
Mononuclear and binuclear transition metal [Co(II), Cu(II), Ni(II) and Zn(II)] acetylsalicylates of the type [M(L)2], [M(L)2Cl2] and [(M)2(L)4] have been prepared and characterized on the basis of their physical, spectral and analytical data. The complexes have been investigated in an in vivo animal model for anti-inflammatory activity and show a better effect and a more potent action than acetylsalicylic acid. 相似文献
976.
Chlorination of microbial polyesters poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxyoctanoate) (PHO) was carried out by passing chlorine gas through their solutions. The chlorine contents in chlorinated PHB (PHB-Cl) and chlorinated PHO (PHO-Cl) were between 5.45 and 23.81 wt % and 28.09 and 39.09 wt %, respectively. Molecular weights of the chlorinated samples were in the range of between one-half to one-fourth of the original values because of hydrolysis during the chlorination process. Thermal properties of the PHO-Cl were dramatically changed with an increase in its glass transition (T(g) = 2 degrees C) and the melting transition (T(m)). The T(g) of PHB-Cl varied from -20 to 10 degrees C, and its T(m) decreased to 148 degrees C. The chlorinated poly(3-hydroxyalkanoate)s (PHA-Cl) were converted to their corresponding quaternary ammonium salts (PHA-N(+)R(3)), sodium sulfate salts (PHA-S), and phenyl derivatives (PHA-Ph). Cross-linked polymers were also formed by a Friedel-Crafts reaction between benzene and PHA-Cl. The modified PHO derivatives were characterized by (1)H NMR and (13)C NMR spectrometry, Fourier transform infrared spectroscopy, gel permeation chromatography, and differential scanning calorimetry techniques. 相似文献
977.
978.
Expression of small interfering RNAs targeted against HIV-1 rev transcripts in human cells 总被引:142,自引:0,他引:142
Lee NS Dohjima T Bauer G Li H Li MJ Ehsani A Salvaterra P Rossi J 《Nature biotechnology》2002,20(5):500-505
979.
Guillem VM Tormo M Revert F Benet I García-Conde J Crespo A Aliño SF 《The journal of gene medicine》2002,4(2):170-182
Background
Specific and efficient delivery of genes into targeted cells is a priority objective in non‐viral gene therapy. Polyethyleneimine‐based polyplexes have been reported to be good non‐viral transfection reagents. However, polyplex‐mediated DNA delivery occurs through a non‐specific mechanism. This article reports the construction of an immunopolyplex, a targeted non‐viral vector based on a polyplex backbone, and its application in gene transfer over human lymphoma cell lines.Methods
Targeting elements (biotin‐labeled antibodies), which should recognize a specific element of the target cell membrane and promote nucleic acid entry into the cell, were attached to the polyplex backbone through a bridge protein (streptavidin). Immunopolyplex transfection activity was studied in several hematological cell lines [Jurkat (CD3+/CD19?), Granta 519 (CD3?/ CD19+), and J.RT3‐T3.5 (CD3?/CD19?)] using the EGFP gene as a reporter gene and anti‐CD3 and anti‐CD19 antibodies as targeting elements. Transfection activity was evaluated via green fluorescence per cell and the percentage of positive cells determined by flow cytometry.Results
A significant selectivity of gene delivery was observed, since the anti‐CD3 immunopolyplex worked only in Jurkat cells while the anti‐CD19 immunopolyplex worked only in the Granta cell line. Moreover, transfection of a CD3+/CD3? cell mixture with anti‐CD3 immunopolyplexes showed up to 16‐fold more transfection in CD3+ than in CD3? cells. Several non‐specific transfection reagents showed poor or no transfection activity.Conclusion
It is concluded that immunopolyplex is a good non‐viral vector for specific and selective nucleic acid delivery. Immunopolyplex design allows easy replacement of the targeting element (antibody) – the streptavidin–polyplex backbone remaining intact – thereby conferring high versatility. Copyright © 2002 John Wiley & Sons, Ltd.980.
Nor?Aini?Abdul?Rahman Yoshihito?Shirai Kazuyuki?ShimizuEmail author Mohd?Ali?Hassan 《Biotechnology and Bioprocess Engineering》2002,7(5):281-288
RecombinantEscherichia coli strain harboring the λp
R-p
L promotor and heterologus poly-β-hydroxybutyrate (PHB) biosynthesis genes was used to investigate the effect of culture conditions
on the efficient PHB production. The expression ofphb genes was induced by a temperature upshift from 33°C to 38°C. The protein expression levels were measured by using two-dimensional
electrophoresis, and the enzyme activities were also measured to understand the effect of culture temperature, carbon sources,
and the dissolved oxygen (DO) concentration on the metabolic regulations. AcetylCoA is an important branch point for PHB production.
The decrease in DO concentration lowers the citrate synthase activity, thus limit the flux toward the TCA cycle, and increase
the flux for PHB production. Since NADPH is required for PHB production, the PHB production does not continue leading the
overproduction of acetate and lactate. Based on these observations, a new operation was considered where DO concentration
was changed periodically, and it was verified its usefulness for the efficient PHB production by experiments. 相似文献