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81.
Data are presented on the cytokinin status of seeds and seed components, at different stages of development in Phaseolus coccineus L., as determined with the soybean callus growth bioassay: A change in cytokinin types according to developmental stage occurred: from biologically very active less polar types (zeatin=Z) at early stages to more polar types (zeatin glucoside=Z9G and zeatin riboside=Zr), with relatively low biological activity, at intermediate and late stages of seed development: When cytokinins were analyzed separately in embryos (embryo proper) and suspensors at two embryonic stages: heart-shaped (A) and middle cotyledonary embryos (stage B) respectively, it was found that: i) at stage A, the suspensor showed cytokinin activity at the level of Z, 2iPA (2-isopentenyladenosine) and Zr, whereas more polar cytokinins (Z9G, Zr) were present in the embryo; ii) at stage B, when the embryo seems to become autonomous for cytokinin supply, there was a relative abundance of active cytokinins (Z, 2iPA) in the embryo to which Z9G activity in the suspensor corresponded. It is concluded that the suspensor plays an essential role in embryogenesis by acting as a hormone source to the early embryo.Abbreviations GA
gibberellic acid
- 2iPA
2-isopentenyladenosine
- Stage A
heart-shaped embryo
- siage B
middle cotyledonary embryo
- Z
zeatin
- Z9G
zeatin glucoside
- Zr
Zeatin riboside 相似文献
82.
Yasuko Mizuno Atsushi Ichikawa Kenkichi Tomita 《Prostaglandins & other lipid mediators》1983,26(5):785-795
The effect of 7-fluoro proscyclilin (PGI2-F), a chemically stable analogue of prostacyclin, on cAMP accumulation in and [3H]PGE binding to mastocytoma P-815 cells was compared with those of the Na salt and methyl ester of prostacyclin (PGI2Na or PGI2Me), which are rapidly inactivated in aqueous solution or metabolized in the tissue.PGIF was as effective as PGI2Me, and slightly less effective than PGI2Na in stimulating cAMP accumulation in mastocytoma cells and rabbit platelets. PGI2F was also more stable than PGI2Me or PGI2Na, and retained its original cAMP elevating activity even after incubation with or without cells for 4 h at 37°C. Cells which had been exposed to PGI2F and then washed free of unbound reagent continued to produced cAMP for more than 3 h. PGI2F was also as effective as PGE1 or PGE2 in displacing [3H]PGE2 bound to the cells. Non-competitive inhibition by PGI2F or PGI2Me of [3H]PGE2 binding to the cells, with apparent Kis of 1.29 μM and 1.13 μM, respectively, indicates the presence of different receptors for PGE2 and for PGI2F or PGI2Me in mastocytoma P-815 cells. 相似文献
83.
Katsuyuki Imai Atsushi Tanaka Ken Fujimori Masa-Oki Yamada 《Experimental cell research》1982,138(2):367-375
A neutral α-glucosidase (EC 3.2.1.20) activity was shown to be associated with granules which are sedimentable at 10 000 g after differential centrifugation of mouse peritoneal macrophage homogenates. When the post-nuclear supernatant was centrifuged in a sucrose density gradient, high activities for neutral α-glucosidase and β-glucuronidase (EC 3.2.1.31) were detected in the bottom fractions because of aggregation of the granules. Neutral α-glucosidase-containing granules were completely disaggregated by the addition of 20 units/ml of heparin and 10 mM Tris-HCl (pH 7.2), which caused only a partial disaggregation of β-glucuronidase-containing granules. The addition of a high concentration of heparin, Tris buffer, or KCl to the gradient gave the same patterns of disaggregation of the granules. Under the condition in which about 50% of the total β-glucuronidase activity was released into the medium, depending on phagocytosis, very little α-glucosidase was released. These observations suggested that neutral α-glucosidase may localize in non-lysosomal granules. 相似文献
84.
The product of the malE—lacZ gene fusion was reported to compete with some proteins including outer membrane lipoprotein in the protein translocation across the Echerichia coli membrane. The fusion product also inhibited colicin E1 export. Furthermore, globomycin, which accumulated prolipoprotein in the membrane, inhibited the translocation of colicin E1 in the wild-type cells, but not in lipoprotein-negative mutant cells. Since colicin E1 contains the internal signal-like sequence [Proc. Natl. Acad. Sci. USA (1982) 79, 2827–2831], these results suggest that colicin E1 is exported by the aid of this sequence at a common site for maltose-binding protein and lipoprotein translocation. 相似文献
85.
Protoplasts prepared from suspension-cultured Vinca rosea cellswere cultured for 5 days. The cell walls regenerated from theprotoplasts were mainly composed of glucans having 1,3- and1,4-linkages. To investigate the molecular species, these glucanswere separated into four fractions: EDTA (50 mM, pH 4.5)-soluble(fraction E), KOH (24%)- soluble but not precipitatable by neutralizationwith acetic acid (fraction K-S), KOH (24%)-soluble and precipitatableby neutralization with acetic acid (fraction K-P), and KOH (24%)-insoluble(fraction C). By means of sugar composition analysis, methylationanalysis, periodate oxidation and enzymatic digestion, the molecularspecies of the glucans contained in the regenerated cell wallswere deduced to be ß-1,4-glucan (cellulose) and ß-1,3-glucan.Fraction C was mainly composed of ß-1,4-glucan; ß-1,3-glucanwas mainly recovered in fraction K-P. The ß-l,3-glucanwas soluble in dilute alkali solution, but was only slightlysoluble in water. The ß-1,3-glucan had an essentiallyunbranched structure, and its weight average molecular weightestimated by gel permeation chromatography was 4.55.0x 104.
1 Present address: Division of Environmental Biology, NationalInstitute for Environmental Studies, Yatabe, Tsukuba, Ibaraki305, Japan (Received May 21, 1981; Accepted October 13, 1981) 相似文献
86.
Takehiko Watanabe Kazutaka Maeyama Atsushi Yamatodani Mitsuko Yamada Yukihiko Kitamura Hiroshi Wada 《Life sciences》1980,26(19):1569-1574
The histamine contents were very low in the whole bodies of various types of mutant mice (Wv/Wv, Wv/W, W/W), in which the number of mast cells was decreased, but the L-histidine decarboxylase activities in these mutant mice were not much lower than in control wild type mice. These findings suggest the presence of high histidine decarboxylase activity in cells other than mast cells. Histidine decarboxylase in the whole body of mice was difficult to assay, because the enzyme was rapidly destroyed by proteases, but inclusion of a protease inhibitor, such as Leupeptin, Antipain, Chymostatin, or Pepstatin in the assay mixture permitted the accurate assay of histidine decarboxylase in crude extracts. 相似文献
87.
Yoshikazu Kuroki Ichiro Matsui Yoshifumi Yamamoto Atsushi Ieshima 《Human genetics》1980,55(2):227-229
Summary Disomic and trisomic cells of a patient with Down syndrome mosaic were used to study the effect of the additional chromosome 21 against an identical genetic background. The frequency of Ag staining and the participation in satellite associations were determined for each pair of acrocentric chromosomes. The additional chromosome 21 of the trisomic cells and its homologues proved to be regularly Ag positive. Therefore the trisomic cells showed more Ag positive chromosomes and more satellite associations per cell than the diploid cells. Thus, no compensation for the additional rRNA-gene dose could be found in the cells of the trisomic line. 相似文献
88.
Toshio Hirano Osamu Teraoka Tsuyoshi Teranishi Izuo Tsityuguchi Hiroko Tohda Atsushi Oikawa 《Microbiology and immunology》1980,24(9):879-886
Autoantibody-producing B cell lines were established from peripheral blood lymphocytes of patients with systemic lupus erythematosus. Peripheral blood lymphocytes obtained from five of seven patients were successfully transformed by Epstein-Barr virus. Two of four established B lymphoblastoid cell lines examined in this study produced anti-nuclear factor antibodies and one of them produced anti-single-stranded DNA and anti-double-stranded DNA antibodies. These results indicate that B cell clones committed to self antigens are transformed by Epstein-Barr virus and continue to produce autoantibodies. In order to establish a monoclonal autoantibody-producing B cell line, the cells were cloned by a limiting dilution method. The data suggest that it is possible to establish a monoclonal autoantibody-producing B cell line by the combination of transformation of B cells by Epstein-Barr virus and extensive cloning. 相似文献
89.
Lemna perpusilla 6746, a short-day duckweed, flowered undercontinuous illumination if some of the SH inhibitors, such ascyanide or tungstate were added to the M-sucrose medium. Theeffect of tungstate was not overcome by simultaneous applicationof molybdate, but deletion of the Mo from the medium was enoughto induce the long-day flowering. In vivo assay of nitrate reductaseactivity suggested that nitrate reduction was not inhibitedby tungstate, CuSO4 or AgNO3 which induced longday flowering.The possibility was suggested that suppression of some Mo-requiringprocess other than nitrate reduction brings about the long-dayflowering in this plant. (Received November 12, 1975; ) 相似文献
90.
The metabolism of d-gluconate-[1-14C] and -[6-14C] by segments from etiolated hypocotyls of Phaseolus mungo has been studied. The release of 14CO2 from gluconate-[1-14C] was greater than that from gluconate-[6-14C] in all parts of hypocotyls examined. Incorporation of the radioactivity from gluconate-[6-14C] into RNA, lignin and aromatic amino acid fractions was greater in the upper (younger) part of the hypocotyls. Incorporation into sugars was greater in the lower (more mature) parts. 相似文献