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101.
Bartelt A Bruns OT Reimer R Hohenberg H Ittrich H Peldschus K Kaul MG Tromsdorf UI Weller H Waurisch C Eychmüller A Gordts PL Rinninger F Bruegelmann K Freund B Nielsen P Merkel M Heeren J 《Nature medicine》2011,17(2):200-205
Brown adipose tissue (BAT) burns fatty acids for heat production to defend the body against cold and has recently been shown to be present in humans. Triglyceride-rich lipoproteins (TRLs) transport lipids in the bloodstream, where the fatty acid moieties are liberated by the action of lipoprotein lipase (LPL). Peripheral organs such as muscle and adipose tissue take up the fatty acids, whereas the remaining cholesterol-rich remnant particles are cleared by the liver. Elevated plasma triglyceride concentrations and prolonged circulation of cholesterol-rich remnants, especially in diabetic dyslipidemia, are risk factors for cardiovascular disease. However, the precise biological role of BAT for TRL clearance remains unclear. Here we show that increased BAT activity induced by short-term cold exposure controls TRL metabolism in mice. Cold exposure drastically accelerated plasma clearance of triglycerides as a result of increased uptake into BAT, a process crucially dependent on local LPL activity and transmembrane receptor CD36. In pathophysiological settings, cold exposure corrected hyperlipidemia and improved deleterious effects of insulin resistance. In conclusion, BAT activity controls vascular lipoprotein homeostasis by inducing a metabolic program that boosts TRL turnover and channels lipids into BAT. Activation of BAT might be a therapeutic approach to reduce elevated triglyceride concentrations and combat obesity in humans. 相似文献
102.
Nandivada H Villa-Diaz LG O'Shea KS Smith GD Krebsbach PH Lahann J 《Nature protocols》2011,6(7):1037-1043
The culture of human embryonic stem (hES) cells in defined and xenogeneic-free conditions will contribute substantially to future biotechnological and medical applications. To achieve this goal, we developed the first fully defined synthetic polymer coating poly[2-(methacryloyloxy)ethyl dimethyl-(3-sulfopropyl)ammonium hydroxide] (PMEDSAH) that sustains long-term growth of hES cells in different culture media. Here we describe a detailed protocol for the reproducible fabrication of PMEDSAH coating on tissue culture polystyrene dishes, and for the feeder-free culture of hES cells on PMEDSAH coating in defined culture medium. This culture system represents a key step toward the fully defined and xenogeneic-free culture of hES cells. 相似文献
103.
Brundert M Heeren J Merkel M Carambia A Herkel J Groitl P Dobner T Ramakrishnan R Moore KJ Rinninger F 《Journal of lipid research》2011,52(4):745-758
The mechanisms of HDL-mediated cholesterol transport from peripheral tissues to the liver are incompletely defined. Here the function of scavenger receptor cluster of differentiation 36 (CD36) for HDL uptake by the liver was investigated. CD36 knockout (KO) mice, which were the model, have a 37% increase (P = 0.008) of plasma HDL cholesterol compared with wild-type (WT) littermates. To explore the mechanism of this increase, HDL metabolism was investigated with HDL radiolabeled in the apolipoprotein (125I) and cholesteryl ester (CE, [3H]) moiety. Liver uptake of [3H] and 125I from HDL decreased in CD36 KO mice and the difference, i. e. hepatic selective CE uptake ([3H]125I), declined (–33%, P = 0.0003) in CD36 KO compared with WT mice. Hepatic HDL holo-particle uptake (125I) decreased (–29%, P = 0.0038) in CD36 KO mice. In vitro, uptake of 125I-/[3H]HDL by primary liver cells from WT or CD36 KO mice revealed a diminished HDL uptake in CD36-deficient hepatocytes. Adenovirus-mediated expression of CD36 in cells induced an increase in selective CE uptake from HDL and a stimulation of holo-particle internalization. In conclusion, CD36 plays a role in HDL uptake in mice and by cultured cells. A physiologic function of CD36 in HDL metabolism in vivo is suggested. 相似文献
104.
Ilana Agmon Tamar Auerbach David Baram Heike Bartels Anat Bashan Rita Berisio Paola Fucini Harly A S Hansen Joerg Harms Maggie Kessler Moshe Peretz Frank Schluenzen Ada Yonath Raz Zarivach 《European journal of biochemistry》2003,270(12):2543-2556
High-resolution crystal structures of large ribosomal subunits from Deinococcus radiodurans complexed with tRNA-mimics indicate that precise substrate positioning, mandatory for efficient protein biosynthesis with no further conformational rearrangements, is governed by remote interactions of the tRNA helical features. Based on the peptidyl transferase center (PTC) architecture, on the placement of tRNA mimics, and on the existence of a two-fold related region consisting of about 180 nucleotides of the 23S RNA, we proposed a unified mechanism integrating peptide bond formation, A-to-P site translocation, and the entrance of the nascent protein into its exit tunnel. This mechanism implies sovereign, albeit correlated, motions of the tRNA termini and includes a spiral rotation of the A-site tRNA-3' end around a local two-fold rotation axis, identified within the PTC. PTC features, ensuring the precise orientation required for the A-site nucleophilic attack on the P-site carbonyl-carbon, guide these motions. Solvent mediated hydrogen transfer appears to facilitate peptide bond formation in conjunction with the spiral rotation. The detection of similar two-fold symmetry-related regions in all known structures of the large ribosomal subunit, indicate the universality of this mechanism, and emphasizes the significance of the ribosomal template for the precise alignment of the substrates as well as for accurate and efficient translocation. The symmetry-related region may also be involved in regulatory tasks, such as signal transmission between the ribosomal features facilitating the entrance and the release of the tRNA molecules. The protein exit tunnel is an additional feature that has a role in cellular regulation. We showed by crystallographic methods that this tunnel is capable of undergoing conformational oscillations and correlated the tunnel mobility with sequence discrimination, gating and intracellular regulation. 相似文献
105.
106.
We studied the plasma beta carotene concentrations in 40 Alzheimer's disease patients and the association with cerebrospinal fluid beta-amyloid 1-40, (Abeta40), cerebrospinal fluid beta-amyloid 1-42 (Abeta42) and cerebrospinal fluid total Tau. We found that patients with plasma beta carotene levels below the 25th percentile had 55% reduced ratios of Abeta40/Tau and 51% reduced ratios of Abeta 40/Abeta 42 compared with patients in the highest quartile. Mean Tau concentrations in the lowest quartile of plasma beta-carotene levels were 74% higher compared with the highest quartile of plasma beta-carotene levels. Thus, we could demonstrate an statistically significant association between beta carotene levels in plasma and neurochemical markers in the cerebrospinal fluid of Alzheimer's disease patients. 相似文献
107.
Poly(2-alkyl-1,3-oxazoline)s (alkyl = methyl, ethyl) with terminal quarternary ammonium groups were synthesized. It could be shown by NMR and ESI-MS that the termination of the living polymerization with N,N-dimethylalkyl(butyl to hexadecyl)amines was quantitative. The novel functions were investigated regarding their antimicrobial potential toward the bacterium Staphylococcus aureus revealing that only quarternary ammonium functions with 12 and more carbons are antibacterial. Using a novel bifunctional initiator, 3-[(tert-butoxycarbonyl)amino]benzyl-p-toluenesulfonate, poly(oxazoline) with a primary amino group at the starting end and an antimicrobial function at the terminal could be synthesized, as confirmed by NMR and ESI-MS measurements. Comparing the bioactivity of polymers with different functions at the starting end and terminated with dimethyldodecylamine revealed that the starting group has a great effect on the antibacterial properties of the distant terminal. The minimal inhibitory concentrations varied from 0.1 mM for polymer derivatives with a BOC-NH-phenyl starting group to 4 mM for poly(oxazoline)s with a free primary amine at the starting end. 相似文献
108.
State-of-the-art in phosphoproteomics 总被引:2,自引:0,他引:2
Presently, phosphorylation of proteins is the most studied and best understood PTM. However, the analysis of phosphoproteins and phosphopeptides is still one of the most challenging tasks in contemporary proteome research. Since not every phosphoprotein is accessible by a certain method and identification of the phosphorylated amino acid residue is required in the majority of cases, various strategies for the detection and localization of phosphorylations have been developed. Identification and localization of protein phosphorylations is mostly done by MS nowadays but phosphoproteins and -peptides are often suppressed in comparison to the unphosphorylated species if measured in complex mixtures. Thus, the isolation of pure phosphopeptide samples is a main task. This review gives an overview over the most frequently used methods in isolation and detection of phosphoproteins and -peptides such as specific enrichment or separation strategies as well as the localization of the phosphorylated residues by various mass spectrometric techniques. 相似文献
109.
This study investigated and correlated physical properties and cell interactions of copolymers obtained by a poly(ethylene glycol) (PEG)-modulated fermentation of Azotobacter vinelandii UWD. PEGs with molecular weights of 400 and 3400 Da and di(ethylene glycol) (DEG) were used to modulate the bacterial synthesis of poly(beta-hydroxybutyrate) (PHB). The PHB crystallinity was determined by wide-angle X-ray scattering (WAXS). Small-angle X-ray scattering (SAXS) showed that lamellar distances decreased between the PHB and the PHB modulated with PEG or DEG. Furthermore, the contact angle of water on the PHB/PEG polymer surfaces decreased when compared to that of PHB. The significant decrease of the contact angle and corresponding increase in surface tension, as well as significant decrease in cell adhesion, suggest the presence of hydrophilic PEG and DEG within the hydrophobic surface. 相似文献
110.