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1.
2.
Aminoglycoside suppression at UAG, UAA and UGA codons in Escherichia coli and human tissue culture cells 总被引:6,自引:0,他引:6
Robin Martin Anne E. Mogg Louise A. Heywood Lars Nitschke Julian F. Burke 《Molecular & general genetics : MGG》1989,217(2-3):411-418
Summary We have compared the suppression of nonsense mutations by aminoglycoside antibiotics inEscherichia coli and in human 293 cells. Six nonsense alleles of the chloramphenicol acetyl transferase (cat) gene, in the vector pRSVcat, were suppressed by growth in G418 and paromomycin. Readthrough at UAG, UAA and UGA codons was monitored with enzyme assays
for chloramphenicol acetyl transferase (CAT), in stably transformed bacteria and during transient expression from the same
plasmid in human 293 tissue culture cells. We have found significant differences in the degree of suppression amongst three
UAG codons and two UAA codons in different mRNA contexts. However, the pattern of these effects are not the same in the two
organisms. Our data suggest that context effects of nonsense suppression may operate under different rules inE. coli and human cells. 相似文献
3.
Dieter Ehlers Ina Sakowski Werher Mohrig 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1989,159(4):481-489
Summary The high affinity of granulocytes of guinea pig and man to glass surfaces is modified by serum. Native serum contains both an adherence-promoting activity, which is related to complement, and components which reduce the adhesiveness of granulocytes. These components are stable at 56°C for 30 min and are tightly bound to the glass surface. -Lipoproteins are candidates for this adherence reducing ability of serum. Adherence promotion by native serum is mediated by coating the glass surface with C3b/C3bi. Human granulocytes from the peripheral blood adhered to glass surfaces coated by native human or guinea pig serum with C3b/C3bi to almost the same extent as in the presence of native serum, but on guinea pig granulocytes elicited in the peritoneal cavity, a cell surface metalloproteinase degraded the C3b/C3bi, thus reducing the adhesiveness of these cells. This proteinase was inhibited by MgEDTA, DTT, and 1,10-phenanthroline, whereby the high adhesiveness of granulocytes was restored to C3b/C3bi-coated glass.Abbreviations
BA
benzamidine hydrochloride
-
BTS
Bacillus thuringiensis subtoxicus
-
DTT
dithiothreitol
-
EAC
-amino-caproic acid
-
gp
guinea pig
-
LDL
low density lipoproteins
-
SEM
scanning electron microscopy 相似文献
4.
The comparison of primary structures is extended to 22 cytochromesb orb
6, 12 cytochromesc
1 orf, and 8 Rieske FeS proteins. Conclusions are drawn as to their phylogenetic relationship as well as on conserved, functionally important amino acids and secondary structures. The results are in favor of two independent quinone binding sites at opposite surfaces of the membrane, topping one of the two hemes of cytochromeb each. 相似文献
5.
Jessica E. Hoogendijk Gerard W. Hensels Ina Zorn Linda Valentijn Emiel A. M. Janssen Marianne de Visser David F. Barker Bram W. Ongerboer de Visser Frank Baas Pieter A. Bolhuis 《Human genetics》1991,88(2):215-218
Summary Recently, it has been shown that Charcot-Marie-Tooth disease type 1a (CMT1a) is linked with a duplication of a DNA segment that is detected by probe VAW409R3, and that is located on chromosome 17p11.2. Here, we show that this duplication also contains VAW412R3a, but not A10-41 and EW503. Accounting for the duplication in recombination analysis, we found recombinants between CMT1a and EW301 and EW502, but not with A10-41, VAW409R3, and VAW412R3. Using pulsed-field gel electrophoresis analysis, we estimated the minimal size of the duplicated region in CMT1a patients to be 1100 kb. 相似文献
6.
X-irradiated oxymyoglobin (MbO2) exhibits electron spin resonance (ESR) spectra at 77 K due to two distinct [FeO2]-centers formed by electron addition to the dioxygen. In single crystals with 17O and 57Fe isotope enrichment in the heme-ligand complex, the full set of spectral parameters is analyzed for one of the centers (gmax = 2.23, gint = 2.13, gmin = 1.97; HOmax = 2.66 mT, HOint = 1.61 mT, HOmin = 0.57 mT; HFe max = 1.62 mT, HFe int = 0.57 mT, HFe min = 0.49 mT) and the iron-dioxygen spin-density distribution and bonding geometry is derived. The g-tensor is evaluated for the second species at 77 K (gmax = 2.25, gint = 2.11, gmin = 1.95). Both centers transform into secondary species at 180 K for which the g-tensor elements are analyzed (gmax = 2.31, gint = 2.18, gmin = 1.93; gmax = 2.35, gint = 2.21, gmin = 1.91). 相似文献
7.
Scavenging of Hydrogen Peroxide in the Endosperm of Ricinus communis by Ascorbate Peroxidase 总被引:6,自引:0,他引:6
The fat-storing endosperm of Ricinus communis L. was found tocontain an ascorbate peroxidase (EC 1.11.1.11
[EC]
), which is nearlyas active as catalase (EC 1.11.1.6
[EC]
) in degradation of hydrogenperoxide (H2O2) at its physiological concentrations. This ascorbateperoxidase probably functions together with monodehydroascorbatereductase (EC 1.6.5.4
[EC]
) or dehydroascorbate reductase (EC 1.8.5.1
[EC]
)and glutathione reductase (EC 1.6.4.2
[EC]
) to remove the H2O2 producedduring the transformation of fat to carbohydrate in the glyoxysomes.The activities of these enzymes as well as the content of ascorbateand glutathione increase parallel to the activities of glyoxysomalmarker enzymes during the course of germination. Inhibitionof catalase by aminotriazole results in increases of the ascorbateperoxidase activity and of the glutathione content. All fourenzymes are predominantly localized in the cytosol of the Ricinusendosperm with low activities found in the plastids and themitochondria. The results suggest, that the ascorbate-dependentH2O2 scavenging pathway, which has been shown to be responsiblefor the reduction of photosynthetically derived H2O2 in thechloroplasts, operates also in the Ricinus endosperm. (Received June 5, 1990; Accepted July 31, 1990) 相似文献
8.
Lars Nitschke Karin Heeger Hans Bender Georg E. Schulz 《Applied microbiology and biotechnology》1990,33(5):542-546
Summary The -cyclodextrin glycosyltransferase (-CGTase) gene was isolated from a -library prepared from Bacillus circulans strain no. 8. It was subcloned into plasmid pTZ and expressed by its endogenous regulatory sequences in Escherichia coli JM 103. The structural gene was sequenced and showed an open reading frame for a polypeptide of 718 amino acid residues. The recombinant -CGTase had the same enzymatic properties as the extracellular CGTase (684 amino acid residues, corresponding to a mol. wt. of 74416) produced by B. circulans strain no. 8. The amino acid sequence showed the highest homology (74.6% identical amino acids) with the CGTase of B. circulans strain F-2, which had been erroneously described as an amylase. The homology with the enzyme from the alkalophilic Bacillus sp. strain no. 1011 was 71.4%. The amino acid sequence derived will be used for elucidating the three-dimensional structure of the enzyme.
Offprint requests to: H. Bender 相似文献
9.
10.
The 3-end of the cDNA encoding the smg GDP dissociation stimulator (smg GDS) protein shares 100% homology with the previously published expressed sequence tag 00038 site. This site extends the 3-end of the smg GDS gene by 212 bp. It has been localized to human chromosome 4. Here, we have refined the localization of smg GDP to human chromosome 4q21-q25 using a mapping panel of rodent/human somatic cell hybrids containing different parts of chromosome 4. This chromosomal localization of smg GDP to 4q21-25 overlaps with a region of allele loss in primary hepatocellular carcinoma (4q13-q26).HGM symbol: RAP1GDS1 相似文献