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21.
Summary A new case of triploid-diploid mosaicism in the lymphocytes of a newborn with multiple malformations is reported, and the origin of the mosaicism is briefly discussed.N.I.H. International Post-doctoral Fellow.Bevoegd Navorser N.F.W.O. 相似文献
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23.
Isolation and partial characterization of an unusual human immunodeficiency retrovirus from two persons of west-central African origin. 总被引:12,自引:4,他引:8 下载免费PDF全文
R De Leys B Vanderborght M Vanden Haesevelde L Heyndrickx A van Geel C Wauters R Bernaerts E Saman P Nijs B Willems et al. 《Journal of virology》1990,64(3):1207-1216
An unusual human retrovirus was isolated from two patients with persistent generalized lymphadenopathy who originate from West-Central Africa and are currently residing in Belgium. Although the virus shared a number of the same biological and morphological properties as human immunodeficiency retrovirus type 1 (HIV-1) and HIV-2, significant antigenic differences could be demonstrated. Several of the viral proteins also differed in molecular weight from the corresponding HIV-1 and HIV-2 proteins. Partial chemical cleavage of the most highly conserved viral proteins resulted in patterns which differed from those of HIV-1 and HIV-2. Furthermore, nucleic acid hybridization experiments were capable of discriminating between the virus types. Sequence analysis of the viral U3 region revealed a unique enhancer organization not found in other immunodeficiency viruses. The data indicated that the new isolate is more closely related to HIV-1 than to HIV-2 but clearly differs in a number of important respects. 相似文献
24.
In this report the authors describe an 8-year-old severely mentally retarded girl with facial features resembling the facial dysmorphism seen in patients with Alagille-Watson syndrome, severe growth retardation and a 46,XX/46,XX,del(20)(pter-->p12.2) mosaicism in fibroblasts. 相似文献
25.
Anterior basal encephalocele in the median cleft face syndrome. Comments on nosology and treatment 总被引:1,自引:0,他引:1
C Grubben J P Fryns F De Zegher H Van Den Berghe 《Genetic counseling (Geneva, Switzerland)》1990,1(2):103-109
Two cases of median cleft syndrome with associated basal encephalocele are presented. The median cleft face syndrome consists of several craniofacial defects and occurs, as far as we know, sporadically. Extracranial defects should be looked for carefully since they may indicate the presence of a specific syndrome with its own prognosis and mode of inheritance. Basal encephaloceles are sometimes part of the syndrome and may cause serious, or even life-threatening, symptoms. With regard to the treatment of basal encephaloceles there still exists a lot of controversion, but most authors agree that it is better to postpone operation until after the age of three because mortality is lower then. 相似文献
26.
Regulation of expression of a cDNA from barley roots encoding a high affinity sulphate transporter 总被引:27,自引:3,他引:24
Frank W. Smith Malcolm J. Hawkesford Paul M. Ealing David T. Clarkson Peter J. Vanden Berg Ann R. Belcher Andrew G.S. Warrilow 《The Plant journal : for cell and molecular biology》1997,12(4):875-884
A cDNA encoding a high-affinity sulphate transporter has been isolated from barley by complementation of a yeast mutant. The cDNA, designated HVST1, encodes a polypeptide of 660 amino acids (Mr = 72 550), which is predicted to have 12 membrane-spanning domains and has extensive sequence homology with other identified eukaryotic sulphate transporters. The Km for sulphate was 6.9 µM when the HVST1 cDNA was expressed in a yeast mutant deficient in the gene encoding for the yeast SUL1 sulphate transporter. The strong pH-dependency of sulphate uptake when HVST1 was expressed heterologously in yeast suggests that the HVST1 polypeptide is a proton/sulphate co-transporter. The gene encoding HVST1 is expressed specifically in root tissues and the abundance of the mRNA is strongly influenced by sulphur nutrition. During sulphur-starvation of barley, the abundance of mRNA corresponding to HVST1, and the capacity of the roots to take up sulphate, both increase. Upon re-supply of sulphate, the abundance of the mRNA corresponding to HVST1, and the capacity of the roots to take up sulphate, decrease rapidly, concomitant with rises in tissue sulphate, cysteine and glutathione contents. Addition of the cysteine precursor, O-acetylserine, to plants grown with adequate sulphur supply, leads to increases in sulphate transporter mRNA, sulphate uptake rates and tissue contents of glutathione and cysteine. It is suggested, that whilst sulphate, cysteine and glutathione may be candidates for negative metabolic regulators of sulphate transporter gene expression, this regulation may be overridden by O-acetylserine acting as a positive regulator. 相似文献
27.
Study of the dynamics of neutralization escape mutants in a chimpanzee naturally infected with the simian immunodeficiency virus SIVcpz-ant. 总被引:2,自引:1,他引:1 下载免费PDF全文
P N Nyambi P Lewi M Peeters W Janssens L Heyndrickx K Fransen K Andries M Vanden Haesevelde J Heeney P Piot G van der Groen 《Journal of virology》1997,71(3):2320-2330
Here we report on the use of spectral map analysis of time-paired sequential neutralization data of 11 serum samples of a chimpanzee naturally infected with a simian immunodeficiency virus (SIVcpz-ant) and 8 primary consecutive SIVcpz-ant isolates, taken at about 4-month intervals. The analysis reveals the existence of three SIVcpz-ant isolate and serum neutralization clusters. Each cluster groups virus isolates and/or sera based on similarities of their neutralization spectra. On average, neutralization escape mutants emerged after 15 months and mounted a neutralization response approximately 8 months later. The entire gp160 regions of eight consecutive isolates were sequenced and analyzed by a new statistical method called polygram, which allowed the deduction of amino acid sequence motifs of gp160 which were specific for SIVcpz-ant isolates belonging to the same isolate neutralization clusters. Changes in specific amino acid quadruplets in V1, V2, C3, V4, V5, and CD4 domains of gp120 and gp40 were seen to correlate with the neutralization clusters with most of the specific changes occurring in the V4 region. This method of analysis may facilitate an understanding of the study of the dynamic interplay between human immunodeficiency virus (HIV) and host neutralization responses as well as providing possible insights into mechanisms of persistence of HIV-1-related lentiviruses in their natural hosts. 相似文献
28.
P Marynen F Van Leuven J J Cassiman H Van den Berghe 《Biochimica et biophysica acta》1984,799(2):187-193
alpha 2-Macroglobulin complexed to proteinases activated during clotting of cystic fibrosis and control sera was quantitated with the complex-specific monoclonal antibody F2B2 . Similar amounts of alpha 2-macroglobulin complexes (between 40 and 90 micrograms/ml) were generated in cystic fibrosis and control sera. Endocytosis of the complexes by normal human fibroblasts was compared to the amount of complexes detected by the F2B2 -radioimmunoassay. Normal uptake was observed with 13 out of 14 cystic fibrosis sera. One cystic fibrosis serum showed strongly reduced endocytosis of the complexes. Complexes isolated from this serum on immobilized F2B2 failed to inhibit binding of purified alpha 2-macroglobulin-trypsin to its receptor, demonstrating deficient receptor-binding of these complexes. The low uptake complexes could not be distinguished from complexes isolated from control or other cystic fibrosis sera by isoelectric focusing, rate electrophoresis or SDS-polyacrylamide gel electrophoresis. 相似文献
29.
Peroxidases in Acetabularia: their possible role in development 总被引:1,自引:0,他引:1
Thérèse Vanden Driessche Claire Kevers Thomas Gaspar Roland Caubergs 《Differentiation; research in biological diversity》1984,27(1-3):175-181
Abstract. Crude enzymatic extracts from Acetabularia exhibit very low peroxidase activity after a lag period. Starch gel electrophoresis of extracts from growing algae shows a single, extremely anodic band. Extracts of small, slow-growing or cap-bearing algae, which do not grow any more, do not exhibit any peroxidase band. Cytochemical staining with benzidine reveals changes in both the quantity and distribution of peroxidase along the polarized Acetabularia cell. The homogenous staining of small algae becomes distributed along a negative apico-basal gradient when the algae initiate their rapid growth phase. This polarized pattern is repeated on the hair whorls. A similar developmental sequence directs cap growth, with an initial intense staining reaction of the primordium, which later leaves only the corona inferior stained blue. Finally, the Acetabularia cell remains slightly blue at the edges of the rhizoidal out-growths and cap rays. Crude extracts of Acetabularia induce a lag in standard horseradish peroxidase (HRP) activity. The inhibitor is always present in small and growing algae; it is sometimes absent or less active in cap-bearing algae. In no case does it change the kinetics of the HRP reaction with guaïacol. The lag is completely suppressed by pretreatment with either H2 O2 or ascorbate oxidase. The changes in peroxidase activity, correlated with developmental stage and according to a polarized gradient, suggest that the enzyme could be involved in some way in the control of morphogenesis in Acetabularia . An inhibitor of peroxidase activity, which disappears as the cap matures, might, in turn, exert a regulatory function. 相似文献
30.
Summary Chromosome analysis with conventional staining, G-banding, and R-banding with 5-bromodeoxyuridine (BrdU) incorporation were performed on the lymphocytes of ten females, who were heterozygous for the fragile X-chromosome. Mental development of these females varied greatly: moderate to severe mental retardation was found in one and moderate mental retardation in four females. Normal to borderline intelligence was found in three and normal intelligence was noted in two further females. The discrepancy in percentage of active fragile X-chromosomes in the five females with moderate mental retardation was found to be 60–100% (mean value: 80%). The three women with normal to borderline intelligence showed a corresponding discrepancy from 57 to 86% (mean value: 77%) of active fragile X-chromosomes. Finally, two female heterozygotes for fragile X with normal intelligence showed 70 and 76% (mean value 73%) of active fragile X-chromosomes. The phenotypic features also did not seem to correspond with the X-chromosome inactivation pattern. Based on the data obtained, we suggest that there is no evident correlation between the frequency of the active fragile X chromosomes and the mental status of these females. 相似文献