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171.
pp60
c-src
kinase activity can be increased by phosphotyrosine dephosphorylation or growth factor-dependent phosphorylation reactions. Expression of the transmembrane phosphotyrosine phosphatase (PTPase) CD45 has been shown to inhibit growth factor receptor signal transduction (Mooney, RA, Freund, GG, Way, BA and Bordwell, KL (1992) J Biol Chem 267, 23443–23446). Here it is shown that PTPase expression decreased platelet-derived growth factor (PDGF)-dependant activation of pp60
c-src
but failed to increase hormone independent (basal) pp60
c-src
activity. PDGF-dependent tyrosine phosphorylation of its receptor was reduced by approximately 60% in cells expressing the PTPase. In contrast, a change in phosphotyrosine content of pp60
c-src
was not detected in response to PDGF or in PTPase+cells. PDGF increased the intrinsic tyrosine kinase activity of pp60
c-src
in both control and PTPase+cells but the effect was smaller in PTPase+cells. In anin vitro assay, hormone-stimulate pp60
c-src
autophosphorylation from PTPase+ cells was decreased 64±22%, and substrate phosphorylation by pp60
c-src
was reduced 54±16% compared to controls. Hormone-independent pp60
c-src
kinase activity was unchanged by expression of the PTPase. pp60
c-src
was, however, anin vitro substrate for CD45, being dephosphorylated at both the regulatory (Tyr527) and kinase domain (Tyr416) residues. In addition,in vitro dephosphorylation by CD45 increased pp60
c-src
activity. These findings suggest that the PDGF receptor was anin vivo substrate of CD45 but pp60
c-src
was not. The lack of activation of pp60
c-src
in the presence of expressed PTPase may demonstrate the importance of compartmentalization and/or accessory proteins to PTPase-substrate interactions.Abbreviations PTPase
phosphotyrosine phosphatase
- PDGF
platelet-derived growth factor
- PMSF
phenylmethylsulfonyl fluoride
- LCA, CD45
leukocyte common antigen
- PBS
phosphate buffered saline
- SDS
sodium dodecyl sulfate
- PAGE
polyacrylamide gel electrophoresis
- DTT
dithiothreitol
- Na3VO4
sodium orthovanadate
- PV
pervanadate
- -ME
-mercaptoethanol 相似文献
172.
173.
Locus Heterogeneity for Waardenburg Syndrome is Predictive of Clinical Subtypes 总被引:5,自引:4,他引:1 下载免费PDF全文
Lindsay A. Farrer Kathleen S. Arnos James H. Asher Clinton T. Baldwin Scott R. Diehl Thomas B. Friedman Jacquie Greenberg Kenneth M. Grundfast Christopher Hoth Anil K. Lalwani Barbara Landa Kate Leverton Aubrey Milunsky Robert Morell Walter E. Nance Valerie Newton Rajkumar Ramesar Valluri S. Rao Jennifer E. Reynolds Theresa B. San Agustin Edward R. Wilcox Ingrid Winship Andrew P. Read 《American journal of human genetics》1994,55(4):728-737
Waardenburg syndrome (WS) is a dominantly inherited and clinically variable syndrome of deafness, pigmentary changes, and distinctive facial features. Clinically, WS type I (WS1) is differentiated from WS type II (WS2) by the high frequency of dystopia canthorum in the family. In some families, WS is caused by mutations in the PAX3 gene on chromosome 2q. We have typed microsatellite markers within and flanking PAX3 in 41 WS1 kindreds and 26 WS2 kindreds in order to estimate the proportion of families with probable mutations in PAX3 and to study the relationship between phenotypic and genotypic heterogeneity. Evaluation of heterogeneity in location scores obtained by multilocus analysis indicated that WS is linked to PAX3 in 60% of all WS families and in 100% of WS1 families. None of the WS2 families were linked. In those families in which equivocal lod scores (between −2 and +1) were found, PAX3 mutations have been identified in 5 of the 15 WS1 families but in none of the 4 WS2 families. Although preliminary studies do not suggest any association between the phenotype and the molecular pathology in 20 families with known PAX3 mutations and in four patients with chromosomal abnormalities in the vicinity of PAX3, the presence of dystopia in multiple family members is a reliable indicator for identifying families likely to have a defect in PAX3. 相似文献
174.
Abstract: Histamine (HA) potently stimulated cyclic AMP accumulation in intact pineal glands taken from light-exposed chicks. The action of HA was stronger in the presence of forskolin and the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). The effect of HA was mimicked by HA H1- and H2-receptor-selective agonists in the following order of potency: HA > 4-methylhistamine (H2) > 2-methylhistamine (H1) > 2-thiazolylethylamine (H1) ≫ dimaprit (H2). The HA H3-receptor-selective agonist (R)α-methylhistamine was poorly active. The effect of HA was antagonized by selective H2-receptor blockers (tiotidine > oxmetidine > cimetidine = ranitidine) and was not significantly affected by the selective H1- and H3-receptor blockers mepyramine and thioperamide. A detailed analysis of an antagonistic action of ranitidine (versus HA) revealed a noncompetitive mode of action of the H2 blocker. The stimulatory action of the H1 agonist 2-thiazolylethylamine (both under basal conditions and in the presence of forskolin or IBMX) was not significantly influenced by three H1-receptor-selective blockers (mepyramine, triprolidine, and diphenhydramine), but it was totally counteracted by ranitidine. Using accepted selective agonists and antagonists of the HA H1, H2, and H3 receptor we were unable to identify clearly the receptor subtype mediating the HA action on the cyclic AMP-generating system of the chick pineal. It is suggested that the receptor under consideration may represent either an H2-like (in terms of mammalian criteria) or avian-specific HA receptor. The data suggest that HA may be considered a modulator of the pineal activity in chicks. 相似文献
175.
Summary Plasmalemmal ionic currents from enzymatically-isolated protoplasts of suspension-cultured carrot cells were investigated by patch-clamp techniques. Among other currents, a novel hyperpolarization-activated, inwardly-rectifying, whole-cell current was observed. The activation of this current was fast in onset, and for large hyperpolarizations a characteristic, rapid voltage-dependent inactivation was seen. Ion substitution experiments indicate that this inward current was due mainly to efflux of chloride ions. No dependence on either internal or external calcium was found, and internal MgATP was not necessary. Surprisingly, zinc did not block this current. In hyperpolarized outside-out patches, inward single-channel chloride currents having an elementary conductance of ca. 100 pS were observed. The open probability increased with hyperpolarization. Similar single-channel currents were activated by slight negative pressure applied to the pipette. These chloride currents could contribute both to the control of membrane potential and in the regulation of osmotic balance in carrot cells.Abbreviations BAPTA
1,2-bis (2-aminophenoxy)ethane-N,N,N,N-tetraacetic acid
- 2,4-D
2,4-dichlorophenoxyacetic acid
- Ex
Nernst equilibrium potential for ion x
- NMDG
N-methyl-D-glucamine
- PMSF
phenylmethylsulfonyl fluoride 相似文献
176.
Summary We irradiated chromosomal spindle fibres in crane-fly spermatocytes with an ultraviolet microbeam of 270 nm wavelength light with total energies near those that cause actin filaments in myofibrils to depolymerize; after irradiation we stained the cells with rhodamine-labelled phalloidin and with anti-tubulin antibodies. In some cells, the irradiation reduced both phalloidin and tubulin staining of the chromosomal spindle fibres; in other cells, the irradiations reduced phalloidin staining but not tubulin staining; in yet other cells, the irradiations reduced tubulin staining but not phalloidin staining. In all irradiated cells in which phalloidin staining was reduced in the irradiated areas phalloidin staining also was reduced poleward from the irradiated areas. These results show that phalloidin staining of chromosomal spindle fibres is not dependent on the presence of kinetochore microtubules, and, therefore, that actin filaments are present in the spindle fibres in vivo. We suggest that actin filaments present in spindle fibres in vivo may be involved in causing chromosome movements during anaphase. 相似文献
177.
Zagrodzki Paweł Mietelski Jerzy W. Krośniak Mirosław Petelenz Barbara 《Biological trace element research》1994,(1):273-277
The aim of this work was to check whether the stable cesium content in forest litter affects the value of radiocesium from
litter-to-mushroom transfer factorTf or not. Total cesium in litter, measured by AAS, varied from 0.1–2.7 μg/g. These data, combined with earlier results for
mushrooms, showed no simple correlation forTf. More complex relationships provided very high correlation coefficients, but their validity needs further investigation. 相似文献
178.
Structural organization and differential expression of three stilbene synthase genes located on a 13 kb grapevine DNA fragment 总被引:10,自引:0,他引:10
Wilfried Wiese Barbara Vornam Elvira Krause Helmut Kindl 《Plant molecular biology》1994,26(2):667-677
A 13 kb DNA fragment was isolated from a grapevine (Vitis var. Optima) genomic library by hybridizing with elicitor-induced stilbene synthase cDNA as a probe. After fragmentation with Eco RI, subcloning and sequencing, two full-size stilbene synthase genes (Vst1 and Vst2) and the 3 end of a third stilbene synthase gene (Vst3) were located within the 13 kb fragment. Vst1 and Vst2, differing only slightly in the coding region, are distinguished in the intron size and in the structure of the promoter region. The 5 flanking region of gene Vst1 contains a TATAA box at nucleotide –48. The substantial structural differences found for the promoters of the two genes are paralleled by a striking difference in the expression of the two genes in elicitor-treated cells. Moreover, the accumulation upon elicitation of six different stilbene synthase mRNAs was studied and found to differ by two orders of magnitude. 相似文献
179.
Maike Petersen Elisabeth Häusler Juliane Meinhard Barbara Karwatzki Claudia Gertlowski 《Plant Cell, Tissue and Organ Culture》1994,38(2-3):171-179
Suspension cultures of Coleus blumei accumulate very high amounts of rosmarinic acid, an ester of caffeic acid and 3,4-dihydroxyphenyllactate, in medium with elevated sucrose concentrations. Since the synthesis of this high level of rosmarinic acid occurs in only five days of the culture period, the activities of the enzymes involved in the biosynthesis are very high. Therefore all the enzymes necessary for the formation of rosmarinic acid from the precursors phenylalanine and tyrosine could be isolated from cell cultures of Coleus blumei: phenylalanine ammonia-lyase, cinnamic acid 4-hydroxylase, hydroxycinnamoyl:CoA ligase, tyrosine aminotransferase, hydroxyphenylpyruvate reductase, rosmarinic acid synthase and two microsomal 3- and 3-hydroxylases. The main characteristics of these enzymes of the proposed biosynthetic pathway of rosmarinic acid will be described.Abbreviations DHPL
3,4-dihydroxyphenyllactate
- DHPP
3,4-dihydroxyphenylpyruvate
- pHPL
4-hydroxyphenyllactate
- pHPP
4-hydroxyphenylpyruvate
- RA
rosmarinic acid 相似文献
180.
Eighteen German families with a history of paramyotonia congenita (PC) were characterised by genetic und mutational analysis at the SCN4A locus, which encodes the -subunit of the adult skeletal muscle sodium channel. We concentrated our analysis primarily on these families to test the hypothesis that a predominance of one common mutation occurs in all German PC families and that this mutation arose in a common ancestor originating in the North-West of the country. The present eighteen PC families exhibit two different mutations (R1448C and R1448H) on various SCN4A dinucleotide repeat haplotypes and therefore the majority of the mutations probably occurred independently. However, the R1448H mutation is extremely frequent in the North-West of Germany (Ravensberger Land) on a specific SCN4A microsatellite haplotype, indicating a founder effect within this subpopulation. Our results suggest that the R1448C/R1448H mutations are by far the most common to be associated with the PC phenotype in the German population.This paper is dedicated to Professor Dr. Dr. Peter Emil Becker on the occasion of this 85th birthday 相似文献