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1.
ANP (atrial natriuretic peptide), a peptide found in granules of mammalian atrial cardiac myocytes, has been shown to be active in regulation of blood pressure and body water homeostasis. The existence of ANP in atrium, pituitary, adrenal gland, and kidney of the rat had been immunocytochemically demonstrated with an antibody against rat ANP (102-126). We used the same antibody in immunocytochemical studies for the detection of ANP in peripheral organs of the tree shrew (Tupaia belangeri). The antibody stained granules in myocytes of cardiac atria which indicated that it reacted with tree shrew ANP. In contrast to the rat, no immunoreactive cells were found in pituitaries and adrenal glands. However, in the kidneys distal tubules in outer medulla and cortex were labeled. Ascending limbs of distal tubules were intensely stained when either the peroxidase-antiperoxidase (PAP) or the indirect immunofluorescence method were used. Collecting ducts and convoluted distal tubules in the outer cortex showed a granular type of staining when the immunofluorescence method was used. These data indicate that ANP is present in epithelial cells of distal tubules and collecting ducts, where it may be involved in the regulation of renal salt excretion. 相似文献
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Flávio Resende 《Planta》1936,25(4):665-666
Ohne ZusammenfassungMit 1 Textabbildung (3 Einzelbildern). 相似文献
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Phosphorylation of a 51-kDa envelope membrane polypeptide involved in protein translocation into chloroplasts 总被引:4,自引:0,他引:4
In this report we demonstrate that a 51-kDa outer-envelope membrane protein (P51) is involved in protein translocation into chloroplasts. Furthermore it is shown that phosphorylation of P51 is functionally related to the process of binding and/or importing precursor proteins into chloroplasts. Several lines of evidence have been obtained supporting this suggestion. First, protein import into chloroplasts was inhibited by the membrane-impermeable agent pyridoxal 5'-phosphate, which has been shown to react with a component of the protein-import apparatus. Phosphorylation of envelope membrane polypeptides using [gamma-32P]ATP in the presence of pyridoxal 5'-phosphate resulted in an increased incorporation of 32P radiolabel into a 51-kDa membrane polypeptide (P51). A close correlation between the inhibition of protein import and the increase in the phosphorylation state of P51, both as a function of PLP concentration, was observed. Second, binding of purified precursor proteins to chloroplasts resulted in a specific increase in the phosphorylation state of P51. This effect was not exerted by the mature form of the precursor protein lacking the presequence. Third, internally generated ATP was able to compete specifically with externally added [gamma-32P]ATP for the phosphorylation of P51. Fourth, digestion of the outer-envelope membrane with low amounts of thermolysin resulted in a loss of protein import activity, which was associated with the removal of the phosphorylation site of P51. Phosphorylation of P51 proceeds with an apparent Km (ATP) of about 5 microM, which is much lower than the ATP concentration required for the protein translocation itself. We suggest that two different ATP-dependent processes are involved in protein translocation into chloroplasts. P51 represent presumably a regulatory component of the protein-import apparatus or the protein receptor itself. 相似文献
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Energy dependence of protein translocation into chloroplasts 总被引:25,自引:0,他引:25
The translocation of in vitro synthesized precursor proteins into intact spinach chloroplasts was investigated with respect to its energy requirement. It was demonstrated that MgATP itself, and not a transmembrane electrochemical gradient across the envelope membrane, promotes protein import. By manipulating the external and the stromal level of MgATP, we provided evidence that MgATP energized the protein import not within the chloroplast but at the outside of the envelope membrane. It is postulated that an MgATP-dependent phosphorylation/dephosphorylation cycle at the outer membrane face was involved in the course of protein translocation into the chloroplast. 相似文献
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Dietrich Flöβner 《Hydrobiologia》1984,108(3):259-263
A new species of Neodiaptomus, N. intermedius n. sp. is described and illustrated. It is compared with related species of the strigilipes — physalipus species group. 相似文献
9.
Autoradiographic detection of the earliest stage of [3H]-uridine incorporation into the cow embryo 总被引:3,自引:0,他引:3
S Camous V Kopecny J E Fléchon 《Biology of the cell / under the auspices of the European Cell Biology Organization》1986,58(3):195-200
Cow embryos, obtained from superovulated heifers on days 3 and 4 after oestrus, were cultured for 20 min in Ménézo's complete culture medium (B2), enriched with 200 microCi/ml of 5-[3H]-uridine. Semi-thin Epon sections of this material were investigated by autoradiography for sites of RNA synthesis. It was found that 5-[3H]-uridine was incorporated into the nucleoplasm and nucleoli only at the end of the 8-cell stage. This suggested that synthesis of hnRNA and rRNA occurred from this stage onwards. Ultrastructural studies were performed on these embryos as well as on other non-incubated 4-cell embryos recovered on day 2. The transformation of dense fibrillar primary nucleoli into functional reticulated nucleoli appeared sooner in the development of cow embryos than in other mammalian species hitherto studied and took place generally during the 8-cell stage. An unusual step in this transformation was represented by the development of a single vacuole in nucleoli at the beginning of this stage (day 3 post-oestrus). 相似文献
10.
Using the indirect immunofluorescence staining technique, the occurrence and localization of proacrosin, the zymogen form of acrosin, was studied during spermatogenesis in the bull, ram, boar and rabbit. Proacrosin staining was demonstrable for the first time in the early haploid spermatid and increased with the differentiation of the spermatid to spermatozoon. The spermatozoon is covered by a cap-like structure of uniform fluorescence corresponding to the acrosomal compartment of the male gamete. No fluorescence could be found in diploid spermatogenic cells, i.e., in spermatogonia and spermatocytes. An identical developmental pattern of proacrosin was observed with the indirect immunoperoxidase staining technique. However, with this staining technique a distinct distribution of proacrosin staining was observed in the acrosome of epididymal and ejaculated spermatozoa of the bull, ram, boar, rabbit and man. Proacrosin seems to be distributed in the acrosome in granules rather than in the homogeneous form, as was indicated by the results of indirect immunofluorescence staining. 相似文献