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991.
Kazuhiro Tashima Hideyuki Yamamoto Chiaki Setoyama Tsunehiko Ono Eishichi Miyamoto 《Journal of neurochemistry》1996,66(1):57-64
Abstract: To investigate the physiological role of Ca2+ /calmodulin-dependent protein kinase II (CaM kinase II) in neuronal differentiation, we transfected the cDNA of the α subunit of mouse CaM kinase II (CaM kinase IIα) into PC12 cells and established clonal cell lines that constitutively express the transfected CaM kinase IIα gene. The expression of CaM kinase IIα was confirmed by northern blot and immunoblot analyses. Northern blot analysis showed that the γ and δ subunits of CaM kinase II are mainly expressed in PC12 cells. Treatment of the cells with ionomycin activated CaM kinase IIα through autophosphorylation and generation of the Ca2+ /calmodulin-independent form. It is interesting that the neurite outgrowth induced by dibutyryl cyclic AMP was inhibited in these cell lines in accordance with the activities of overexpressed CaM kinase IIα. The activity of cyclic AMP-dependent protein kinase showed similar levels among these cell lines. These results suggest that CaM kinase II is involved in the modulation of the neurite outgrowth induced by activation of the cyclic AMP system. 相似文献
992.
I. Fujii Y. Ono H. Tada K. Gomi Y. Ebizuka U. Sankawa 《Molecular & general genetics : MGG》1996,253(1-2):1-10
The geneCAL1 (also known asCDC43) ofSaccharomyces cerevisiae encodes the subunit of geranylgeranyl transferase I (GGTase I), which modifies several small GTPases. Biochemical analyses of the mutant enzymes encoded bycall-1, andcdc43-2 tocdc43-7, expressed in bacteria, have shown that all of the mutant enzymes possess reduced activity, and that none shows temperature-sensitive enzymatic activities. Nonetheless, all of thecall/cdc43 mutants show temperature-sensitive growth phenotypes. Increase in soluble pools of the small GTPases was observed in the yeast mutant cells at the restrictive temperature in vivo, suggesting that the yeast prenylation pathway itself is temperature sensitive. Thecall-1 mutation, located most proximal to the C-terminus of the protein, differs from the othercdc43 mutations in several respects. An increase in soluble Rholp was observed in thecall-1 strain grown at the restrictive temperature. The temperature-sensitive phenotype ofcall-1 is most efficiently suppressed by overproduction of Rholp. Overproduction of the other essential target, Cdc42p, in contrast, is deleterious incall-1 cells, but not in othercdc43 mutants or the wild-type strains. Thecdc43-5 mutant cells accumulate Cdc42p in soluble pools andcdc43-5 is suppressed by overproduction of Cdc42p. Thus, several phenotypic differences are observed among thecall/cdc43 mutations, possibly due to alterations in substrate specificity caused by the mutations. 相似文献
993.
The loss of PSII activity (water 相似文献
994.
Purification and Properties of Flavin- and Molybdenum-Containing Aldehyde Oxidase from Coleoptiles of Maize 总被引:12,自引:1,他引:11 下载免费PDF全文
Aldehyde oxidase (AO; EC 1.2.3.1) that could oxidize indole-3-acetaldehyde into indole-3-acetic acid was purified approximately 2000-fold from coleoptiles of 3-d-old maize (Zea mays L.) seedlings. The apparent molecular mass of the native enzyme was about 300 kD as estimated by gel-filtration column chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the enzyme was composed of 150-kD subunits. It contained flavin adenine dinucleotide, iron, and molybdenum as prosthetic groups and had absorption peaks in the visible region (300-600 nm). To our knowledge, this is the first demonstration of the presence of flavin adenine dinucleotide and metals in plant AO. Other aromatic aldehydes such as indole-3-aldehyde and benzaldehyde also served as good substrates, but N-methylnicotinamide, a good substrate for animal AO, was not oxidized. 2-Mercaptoethanol, p-chloromercu-ribenzoate, and iodoacetate partially inhibited the activity, but well-known inhibitors of animal AO, such as menadione and estradiol, caused no reduction in activity. These results indicate that, although maize AO is similar to animal enzymes in molecular mass and cofactor components, it differs in substrate specificity and susceptibility to inhibitors. Immunoblotting analysis with mouse polyclonal antibodies raised against the purified maize AO showed that the enzyme was relatively rich in the apical region of maize coleoptiles. The possible role of this enzyme is discussed in relation to phytohormone biosynthesis in plants. 相似文献
995.
A field observation of the dragonflyNannophya pygmaea revealed that males prefer some territorial sites to others, and that these same sites attract more females than others (Tsubaki
& Ono, 1986, 1987). In this paper, we asked if males choose territorial sites in response to female dispersion or distribution
of resources. We conducted 3 types of removal experiments to test the following 2 hypotheses; (1) a male may assess the territory
quality by the female encounter rate at his site (learning), (2) a male may assess the resource quality (or quantity) in the
territory. The results of our experiments show that males discriminate attractive and less attractive territorial sites without
any mating experience within the study area. Moreover, the territorial site preference of males was not affected by the mating
experience. Therefore, males probably choose territorial sites by resource quality rather than by female dispersion. 相似文献
996.
997.
Immunofluorescence staining with an antiserum raised against a presumptive meiotic histone, which has been shown to appear
prior to male meiosis in liliaceous plants, preferentially stained the centromere (kinetochore) region of meiotic chromosomes
in microsporocytes and megasporocytes. Using this antiserum, we were able clearly to visualize the centromeres at all important
meiotic stages in microsporocytes, namely, the association and fusion of centromeres of homologous chromosomes at zygotene-pachytene
in prophase I, the disjunction of the homologous centromeres at diplotene, the doubling of each centromere at metaphase I
and nonseparation of the sister centromeres at anaphase I, by confocal laser scanning microscopy. Thus, this report provides
a complete picture of the behavior of centromeres during meiosis in a eukaryote for the first time. This antiserum also decorated
centromeres during female meiosis in cryo-sectioned megasporocytes, but did not stain the centromeres of mitotic chromosomes
in root-tip meristem. From these observations, it is suggested that a meiosis-specific centromere protein is required for
the meiosis-specific behavior of the centromere.
Received: 12 May 1997; in revised form: 20 August 1997 / Accepted: 25 August 1997 相似文献
998.
Characterization of human immunodeficiency virus type 1 matrix revertants: effects on virus assembly, Gag processing, and Env incorporation into virions. 总被引:5,自引:3,他引:2 下载免费PDF全文
The matrix protein of human immunodeficiency virus type 1 (HIV-1) has been postulated to serve a variety of functions in the virus life cycle. Previously, we introduced a large number of mutations into the HIV-1 matrix and determined the effects on virus replication. These studies identified domains involved in virus assembly and release and envelope glycoprotein incorporation into virions. Here we describe the identification and characterization of viral revertants containing second-site changes in the matrix which compensate for the effects of four of the original mutations on matrix function. Specifically, mutations at matrix residues 4 and 6 severely impaired virus assembly and release; substitutions at residues 4 and 6 reversed the phenotype of the amino acid 4 change while second-site mutations at matrix positions 10, 69, and 97 partially or fully reversed the phenotype of the amino acid 6 substitution. A mutation at matrix residue 62 reversed the effect of a position 34 change which blocks envelope glycoprotein incorporation into virions, and substitutions at residues 27 and 51 reversed the phenotype of a position 86 mutation which redirects virus assembly to the cytoplasm. In addition to determining the effects of the compensatory changes in the context of the original mutations, we also introduced and analyzed the second-site changes alone in the context of the wild-type molecular clone. The data presented here define potential intermolecular and intramolecular interactions which occur in the matrix during the virus life cycle and have implications for our understanding of the relationship between matrix structure and function. 相似文献
999.
Disassembly and reassembly of cortical microtubules (MT) during and after segregative cell division (SCO) in Dictyosphaeria cavernosa (Forssk.) Børgesen were observed using fluorescence microscopy. Parallel cortical MT in a mother cell were intact just after the initiation of SCD, but soon circular, MT-free patches appeared. Protoplasmic contraction enlarged the patches, and in these areas, the protoplasm eventually became perforated. Long and undulating cortical MT were arranged densely in the reticulate protoplasm. During further protoplasmic contraction, cortical MT appeared to be random and decreased in density. Finally, short and random cortical MT were present in the segregated protoplasts. Parallel cortical MT reassembled in the expanding daughter cells. After the daughter cells came in contact with one another, a radial system of cortical MT was constructed at the side that faced the inside of the mother cell wall. A microtubule inhibitor (amiprophos methyl, APM) had no effect on SCO. Segregative cell division was not induced directly by mechanical wounding. A comparison between SCO and wound-induced protoplasmic contraction was made. 相似文献
1000.
Ichiro Ono Keizo Matsuda Sachiko Kanno 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1996,678(2):384
A column-switching high-performance liquid chromatography method with ultraviolet detection at 210 nm has been developed for the determination of N-(trans-4-isopropylcyclohexylcarbonyl)-d-phenylalanine (AY4166, I) in human plasma. Plasma samples were prepared by solid-phase extraction with Sep-Pak Light tC18, followed by HPLC. The calibration graph for I was linear in the range 0.1–20 μg/ml. The limit of quantitation of I, in plasma, was 0.05 μg/ml. The recovery of spiked I (0.5 μg/ml) to drug-free plasma was over 92% and the relative standard deviation of spiked I (0.5 μg/ml) compared to drug-free plasma was 4.3% (n = 8). 相似文献