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231.
Leonid I. Penkov Evgeni S. Platonov Oksana V. Mironova Boris V. Konyukhov 《Development, growth & differentiation》1996,38(3):263-270
This study describes the effects of 5-azacytidine (5-azaC) on the development of diploid parthenogenetic embryos (PE) of CBA, C57BL/6 and (CBA × C57BL/6)F1 mice in vitro at the 1-cell or the blastocyst stage or in vivo after implantation. Our findings indicate that genomic imprinting is modulated by genetic background. Non-fertilized C57BL/6 eggs form diploid parthenogenetic blastocysts at a much higher frequency than CBA eggs. Eggs from F1 hybrid females form parthenogenetic blastocysts at an approximately intermediate level between these inbred strains of mice. C57BL/6 PE do not develop to the somite stages. In contrast, CBA PE and F1 PE develop to various somite stages. Following administration of 5–azaC at 1.0 μmol/L in vitro at the 1- -cell stage, the number of implantations of C57BL/6 PE transferred to pseudopregnant females increased. In contrast, the number of implantations and somite F1 PE did not significantly change following exposure to 5–azaC. However, administration of 5-azaC at the 1-cell stage stimulates development of somite F1 PE. Administration of 5-azaC at 0.2 and 1.0 μmol/L in vitro at the blastocyst stage did not change the number of implantations of C57BL/6 PE. However, the number of implantations and somite CBA PE decreased. After injection of 5azaC at 0.24mg/kg in vivo at day 8 of gestation, some F1 PE developed to 26–35 somites compared with a maximum of 25 somites in controls. The different effects of 5-azaC on the development of PE depend upon the mouse strain used and the stage of development. 相似文献
232.
Leonid Yu. Sklyarov Irina N. Sbitneva Nadezhda A. Kopina 《Letters in Peptide Science》1995,2(3-4):247-252
Summary Heterocycles (pyridines and pyrroles) obtained from amino acid derivatives and unsaturated compounds can be considered as peptidomimetics. These compounds contain amino acid radicals and modified, nonhydrolysable peptide bonds (micromimetics). The polyfunctionality of pyridoxine (one of the most available pyridines, derived from N-formyl -alanine amide/ester) offers the possibility for use in the synthesis of multiple peptides (MPs). In view of the fact that MPs have certain structures and molecular weights and also owing to the proximity of several peptide chains, they may be considered as models of proteins and even of cell surfaces (macromimetics). Dendritic compounds — multiple spherical peptides — most closely imitate globular proteins. The potential for macromimetics to model the various functions of biopolymers is investigated here. 相似文献
233.
Confocal microscopy of cells implanted into tissue blocks: Cell migration in long-term histocultures
Leonid B. Margolis Svetlana E. Glushakova Boris A. Baibakov Carlos Collin Joshua Zimmerberg 《In vitro cellular & developmental biology. Animal》1995,31(3):221-226
Summary In three-dimensional tissues in vivo, cells find themselves in a unique, heterogeneous microenvironment among various cellular
and noncellular elements. Cells are greatly affected by and contribute to their physical and chemical microenvironments. However,
live cells are currently studied predominantly in homogeneous monolayer cultures where newly established contacts might be
fundamentally different from contacts in vivo. Several systems have been suggested to simulate the three-dimensional environment
of real tissue. In this report, we describe a new system for studying cell behavior inside real tissues in vitro. By fluorescently
labeling mouse tumor cells, then implanting them into cultured tissue blocks (histocultures), we have observed cellular location
and followed their locomotion, within tissues in vitro for days. We discuss the potential of the described system for studying
different aspects of cell behavior in a nativelike microenvironment. 相似文献
234.
Leonid Margolis Boris Baibakov Carlos Collin Sidney A. Simon 《In vitro cellular & developmental biology. Animal》1995,31(6):456-461
Summary A three-dimensional histoculture of wet stratified squamous epithelium of rat lingual frenulum was cultured on a liquid-air
interface. The tissue retained its morphology for many days in culture. During this period the vast majority of the epithelial
cells remained viable and exhibited dye (lucifer yellow) coupling in all living epithelial strata. Dye coupling was determined
using two methods: the conventional intracellular injection method, and a new method—“cut-loading.” In the cut-loading method,
an incision is made in the epithelium in the presence of dye, and intracellular diffusion of dye throughout the epithelium
was measured using confocal microscopy. The basolateral surface of the lingual frenulum also acted as a substrate for neuroblastoma
cells to grow without exogenously added trophic factors. These neuroblastoma cells grow neurites that establish contacts with
epithelial cells. This preparation can serve as a model for investigating interactions among epithelial cells and between
nerves and epithelial cells. 相似文献
235.
Danil I. Peregud Alexander A. Yakovlev Mikhail Yu. Stepanichev Mikhail V. Onufriev Leonid F. Panchenko Natalia V. Gulyaeva 《Cellular and molecular neurobiology》2016,36(6):839-849
Nitric oxide (NO) mediates pharmacological effects of opiates including dependence and abstinence. Modulation of NO synthesis during the induction phase of morphine dependence affects manifestations of morphine withdrawal syndrome, though little is known about mechanisms underlying this phenomenon. Neurotrophic and growth factors are involved in neuronal adaptation during opiate dependence. NO-dependent modulation of morphine dependence may be mediated by changes in expression and activity of neurotrophic and/or growth factors in the brain. Here, we studied the effects of NO synthesis inhibition during the induction phase of morphine dependence on the expression of brain-derived neurotrophic factor (BDNF), glial-derived neurotrophic factor (GDNF), nerve growth factor (NGF), and insulin-like growth factor 1 (IGF1) as well as their receptors in rat brain regions after spontaneous morphine withdrawal in dependent animals. Morphine dependence in rats was induced within 6 days by 12 injections of morphine in increasing doses (10–100 mg/kg), and NO synthase inhibitor L-NG-nitroarginine methyl ester (L-NAME) (10 mg/kg) was given 1 h before each morphine injection. The expression of the BDNF, GDNF, NGF, IGF1, and their receptors in the frontal cortex, striatum, hippocampus, and midbrain was assessed 40 h after morphine withdrawal. L-NAME treatment during morphine intoxication resulted in an aggravation of the spontaneous morphine withdrawal severity. Morphine withdrawal was accompanied by upregulation of BDNF, IGF1, and their receptors TrkB and IGF1R, respectively, on the mRNA level in the frontal cortex, and only BDNF in hippocampus and midbrain. L-NAME administration during morphine intoxication decreased abstinence-induced upregulation of these mRNAs in the frontal cortex, hippocampus and midbrain. L-NAME prevented from abstinence-induced elevation of mature but not pro-form of BDNF polypeptide in the frontal cortex. While morphine abstinence did not affect TrkB protein levels as well as its phosphorylation status, inhibition of NO synthesis decreased levels of phosphorylated TrkB after withdrawal. Thus, NO signaling during induction of dependence may be involved in the mechanisms of BDNF expression and processing at abstinence, thereby affecting signaling through TrkB in the frontal cortex. 相似文献
236.
Sergey N. Mikhailov Alexandra N. Zakharova Mikhail S. Drenichev Andrey V. Ershov Mariya A. Kasatkina Leonid V. Vladimirov 《Nucleosides, nucleotides & nucleic acids》2016,35(3):114-129
In medical and pharmaceutical applications, chitosan is used as a component of hydrogels–macromolecular networks swollen in water. Chemical hydrogels are formed by covalent links between the crosslinking reagents and amino functionalities of chitosan. To date, the most commonly used chitosan crosslinkers are dialdehydes, such as glutaraldehyde (GA). We have developed novel GA like crosslinkers with additional functional groups–dialdehyde derivatives of uridine (oUrd) and nucleotides (oUMP and oAMP)–leading to chitosan-based biomaterials with new properties. The process of chitosan crosslinking was investigated in details and compared to crosslinking with GA. The rates of crosslinking with oUMP, oAMP, and GA were essentially the same, though much higher than in the case of oUrd. The remarkable difference in the crosslinking properties of nucleoside and nucleotide dialdehydes can be clearly attributed to the presence of the phosphate group in nucleotides that participates in the gelation process through ionic interactions with the amino groups of chitosan. Using NMR spectroscopy, we have not observed the formation of aldimine bonds. It can be concluded that the real number of crosslinks needed to cause gelation of chitosan chains may be less than 1%. 相似文献
237.
Irene V. Budunova Leonid A. Mittelman Gennady A. Belitsky 《Cell biology and toxicology》1989,5(1):77-89
The effect of the tumor promoters 12-O-tetradecanoylphorbol-13-acetate (TPA), mezerein, teleocidin, anthralin, the Ca2+-ionophore A23187, butylated hydroxytoluene (BHT), dichlordiphenyltrichloroethane (DDT) and phenobarbital (PB) on lucifer yellow transfer in cultures of SV-40-transformed Djungarian hamster fibroblasts was studied. TPA, mezerein, teleocidin, A23187, DDT and BHT exerted a strong inhibitory effect on cell-to-cell dye transfer. Anthralin uncoupled cells in 3 experiments out of 6. PB appeared to enhance lucifer yellow transfer. Sodium nitrite, a substance with unknown promoting activity, effectively uncoupled cells. All the promoters investigated had a reversible effect on the dye transfer. The value of the dye transfer method for promoter screening is discussed.Abbreviations BHT
butylated hydroxytoluene
- DDT
dichlordiphenyltrichloroethane
- LY
Lucifer Yellow
- PB
phenobarbital
- TPA
12-O-tetradecanoylphorbol-13-acetate 相似文献
238.
Alexander Zaslavsky Pedro Madeira Leonid Breydo Vladimir N. Uversky Arnon Chait Boris Zaslavsky 《Biochimica et Biophysica Acta - Proteins and Proteomics》2013,1834(2):583-592
Partitioning of a protein in an aqueous two-phase system (ATPS) is governed by interactions of the protein with aqueous media in the two phases. Here we describe how partitioning of proteins in a set of ATPS of different compositions can be used to quantify differences between 3D structures of closely related proteins. We also provide perspective on practical applications of the technology when comparative analysis of the higher-order structure of proteins is desired. 相似文献
239.
Leonid Teytelman Bilge ?zayd?n Oliver Zill Philippe Lefran?ois Michael Snyder Jasper Rine Michael B. Eisen 《PloS one》2009,4(8)
Chromatin has an impact on recombination, repair, replication, and evolution of DNA. Here we report that chromatin structure also affects laboratory DNA manipulation in ways that distort the results of chromatin immunoprecipitation (ChIP) experiments. We initially discovered this effect at the Saccharomyces cerevisiae HMR locus, where we found that silenced chromatin was refractory to shearing, relative to euchromatin. Using input samples from ChIP-Seq studies, we detected a similar bias throughout the heterochromatic portions of the yeast genome. We also observed significant chromatin-related effects at telomeres, protein binding sites, and genes, reflected in the variation of input-Seq coverage. Experimental tests of candidate regions showed that chromatin influenced shearing at some loci, and that chromatin could also lead to enriched or depleted DNA levels in prepared samples, independently of shearing effects. Our results suggested that assays relying on immunoprecipitation of chromatin will be biased by intrinsic differences between regions packaged into different chromatin structures - biases which have been largely ignored to date. These results established the pervasiveness of this bias genome-wide, and suggested that this bias can be used to detect differences in chromatin structures across the genome. 相似文献
240.