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961.
962.
In this work a model envisaging the integrated optimization of bioreaction and downstream processing is presented. This model extends the work presented in part 1 of this pair of papers by adding ultrafiltration to process optimization. The new operational parameters include ultrafiltration time, pressure, and stirring rate. For global optimization, the model uses as constraints the final product titer and quality to be achieved after downstream processing. This extended model was validated with the same system used in part 1, i.e., PA317 cells producing a recombinant retrovirus containing the LacZ gene as a marker in stirred tanks using porous supports. Optimization of the extended model led to the conclusion that bioreaction should have two steps, batch and perfusion, similar to what was found in part 1. Ultrafiltration in a stirred cell should be performed at low pressures and stirring rates to reduce the losses of infective retroviruses. Sensitivity analysis performed on the results of the integrated optimization showed that under optimal conditions the productivity is less sensitive to the parameters related to ultrafiltration than to those associated with bioreaction. These results were interpreted as reflecting the high yield of ultrafiltration (90%). The relevance of the model extension to perform integrated optimization was also demonstrated since a restriction in the specific ultrafiltration area in downstream processing conditioned perfusion duration and perfusion rate in bioreaction. This clearly indicates that overall process optimization cannot be achieved without integrated optimization. 相似文献
963.
Wegrowski Y Gillery P Kotlarz G Perreau C Georges N Maquart FX 《Molecular and cellular biochemistry》2000,205(1-2):125-131
Cell culture in collagen lattice is known to be a more physiological model than monolayer for studying the regulation of extracellular matrix protein deposition. The synthesis of sulfated glycosaminoglycans (GAG) and dermatan sulfate (DS) proteoglycans by 3 cell strains were studied in confluent monolayers grown on plastic surface, in comparison to fully retracted collagen lattices. Cells were labelled with35S-sulfate, followed by GAG and proteoglycan analysis by cellulose acetate and SDS-polyacrylamide gel electrophoresis, respectively. The 3 cell strains contracted the lattice in a similar way. In monolayer cultures, the major part of GAG was secreted into culture medium whereas in lattice cultures of dermal fibroblasts and osteosarcoma MG-63 cells but not fibrosarcoma HT-1080 cells, a higher proportion of GAGs, including dermatan sulfate, was retained within the lattices. Small DS proteoglycans, decorin and biglycan, were detected in fibroblasts and MG-63 cultures. They were preferentially trapped within the collagen gel. In retracted lattices, decorin had a higher Mr than in monolayer. Biglycan was detected in monolayer and lattice cultures of MG-63 cells but in lattice cultures only in the case of fibroblasts. In this last case, an up regulation of biglycan mRNA steady state level and down regulation of decorin mRNA was observed, in comparison to monolayers, indicating that collagen can modulate the phenotypical expression of small proteoglycan genes.Supported by a fellowship from the Centre National de la Recherche Scientifique 相似文献
964.
Sauer S Lechner D Berlin K Plançon C Heuermann A Lehrach H Gut IG 《Nucleic acids research》2000,28(23):e100
Recently a facile method for genotyping single nucleotide polymorphisms (SNPs) using MALDI mass spectrometry, termed the GOOD assay, was developed. It does not require any purification and is performed with simple liquid handling, thermal incubation and cycling steps. Although this method is well suited to automation and high-throughput analysis of SNPs, it did not allow full flexibility due to lack of certain reagents. A complete set of β-cyanoethyl phosphoramidites is presented herein that give this SNP genotyping method full sequence and multiplex capabilities. Applications to SNP genotyping in the prion protein gene, the β-2-adrenergic receptor gene and the angiotensin converting enzyme gene using the GOOD assay are demonstrated. Because SNP genotyping technologies are generally very sensitive to varying DNA quality, the GOOD assay has been stabilised and optimised for low quality DNA. A template extraction method is introduced that allows genotyping from tissue that was taken while placing an ear tag on an animal. This dramatically facilitates the application of genotyping to animal agricultural applications, as it demonstrates that expensive and cumbersome DNA extraction procedures prior to genotyping can be avoided. 相似文献
965.
Pastor J Lafon M Travé-Massuyès L Démonet JF Doyon B Celsis P 《Biological cybernetics》2000,82(1):49-59
Today, cognitive functions are considered to be the offspring of the activity of large-scale networks of functionally interconnected
cerebral regions. The interpretation of cerebral activation data provided by functional imaging has therefore recently moved
to the search for the effective connectivity of activated regions, which aims at understanding the role of anatomical links
in the activation propagation. Our assumption is that only causal connectivity can offer a real understanding of the links
between brain and mind. Causal connectivity is based on the anatomical connection pattern, the information processing within
cerebral regions and the causal influences that connected regions exert on each other. In our approach, the information processing
within a region is implemented by a causal network of functional primitives, which are the interpretation of integrated biological
properties. Our choice of a qualitative representation of information reflects the fact that cerebral activation data are
only the approximate view, provided by imaging techniques, of the real cerebral activity. This explicit modeling approach
allows the formulation and the simulation of functional and physiological assumptions about activation data. Two alternative
models explaining results of the striate cortex activation described by Fox and Raichle (Fox PT, Raichle ME (1984) J. Neurophysiol
51:1109–1120; Fox PT, Raichle ME (1985) Ann Neurol 17:303–305) are provided as an example of our approach.
Received: 22 December 1998 / Accepted in revised form: 23 June 1999 相似文献
966.
Chemosensory proteins from the proboscis of mamestra brassicae 总被引:7,自引:0,他引:7
Nagnan-Le Meillour P Cain AH Jacquin-Joly E François MC Ramachandran S Maida R Steinbrecht RA 《Chemical senses》2000,25(5):541-553
Soluble, low molecular weight proteins were immunodetected in proboscis extracts of Mamestra brassicae males by Western blot, using antibodies raised against the general odorant-binding protein of the moth Antheraea polyphemus. The same antibodies weakly labelled the sensillum lymph and subcuticular space of sensilla styloconica on ultrathin sections of the proboscis. The morphology of sensilla styloconica is described. The immunodetected proteins yielded several N-terminal sequences, three of which showed strong affinity for tritiated analogues of pheromonal compounds of M. brassicae in binding assays. The cDNAs coding for these sequences were cloned and it was shown that the new proteins are related to the OS-D protein of DROSOPHILA: They are named chemosensory proteins (CSP-MBRA:A1-CSP-MBRA:A5 and CSP-MBRA:B1 and CSP-MBRA:B2) and may have an odorant-binding protein-like function. A common localization in both olfaction and taste organs suggests a physiological role depending on the cellular environment. 相似文献
967.
The nucleolus is a very dynamic structure able rapidly to adapt its activity to the cellular metabolic state. An interesting physiological model characterized by drastic modifications of cellular metabolism is represented by hibernating animals. In the present study we investigated the hepatocyte nuclei of euthermic and hibernating edible dormice (Glis glis) with the aim of revealing, by means of ultrastructural and immunocytochemical analyses, possible modifications of nucleolar components during hibernation. Our observations demonstrate that, in deep hibernation, nucleoli undergo structural and molecular modifications: (a) they show numerous nucleoplasmic invaginations and clumps of dense fibrillar component extend from the nucleolar surface; (b) they are frequently in contact with coiled bodies and fibro-granular material, two nuclear bodies usually occurring in the nucleoplasm; (c) the dense fibrillar component contains significant amounts of small nuclear ribonucleoproteins, splicing factors usually distributed in the nucleoplasm. Taken together, these results suggest that during hibernation complex relationships are established between the nucleolus and nucleoplasm, probably related to functional activities peculiar to this physiological phase. However, since no evident nucleolar modification was found in early hibernating dormice, it seems likely that the particular structural and molecular arrangement of nucleoli establishes progressively during hibernation, becoming evident only in the deepest phase, and then disappears upon arousal. 相似文献
968.
A simple method to take macrophotographs that show details even in the microsurgical field was discussed. The method uses any single lens up to 80 mm or any zoom lens in the reverse position with a single-lens reflex camera. In this manner, high reproduction ratios larger than the actual size of the object can be achieved. 相似文献
969.
Mesnard F Azaroual N Marty D Fliniaux MA Robins RJ Vermeersch G Monti JP 《Planta》2000,210(3):446-453
Nitrogen metabolism was monitored in suspension cultured cells of Nicotiana plumbaginifolia Viv. using nuclear magnetic resonance (NMR) spectroscopy following the feeding of (15NH4)2SO4 and K15NO3. By using two-dimensional 15N-1H NMR with heteronuclear single-quantum-coherence spectroscopy and heteronuclear multiple-bond-coherence spectroscopy sequences,
an enhanced resolution of the incorporation of 15N label into a range of compounds could be detected. Thus, in addition to the amino acids normally observed in one-dimensional
15N NMR (glutamine, aspartate, alanine), several other amino acids could be resolved, notably serine, glycine and proline. Furthermore,
it was found that the peak normally assigned to the non-protein amino-acid γ-aminobutyric acid in the one-dimensional 15N NMR spectrum was resolved into a several components. A peak of N-acetylated compounds was resolved, probably composed of the intermediates in arginine biosynthesis, N-acetylglutamate and N-acetylornithine and, possibly, the intermediate of putrescine degradation into γ-aminobutyric acid, N-acetylputrescine. The occurrence of 15N-label in agmatine and the low detection of labelled putrescine indicate that crucial intermediates of the pathway from glutamate
to polyamines and/or the tobacco alkaloids could be monitored. For the first time, labelling of the peptide glutathione and
of the nucleotide uridine could be seen.
Received: 29 March 1999 / Accepted: 15 July 1999 相似文献
970.