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排序方式: 共有592条查询结果,搜索用时 359 毫秒
1.
T Shirane 《The Journal of experimental zoology》1987,243(3):495-502
Peanut lectin (PNA) or N-acetylgalactosamine (galNA, a part of the disaccharide unit which is recognized by PNA) was injected into the coelomic cavity of anuran larvae at the developmental stages during which the genital ridges were growing, and the effect of these compounds on the initial determination of gonadal sex was examined. The treatment with PNA tended to inhibit (or perturb) the expression of feminizing gene(s) in Rana japonica, and of both feminizing and masculinizing genes in R. nigromaculata. In contrast, treatment with galNA suppressed the expression of masculinizing gene(s) considerably. In terms of the initial determination of gonadal sex during normal development, these results suggest that the PNA-affinity molecule (PLAM) of primordial germ cells acts as a trigger for the expression of genes that control sexual differentiation of somatic cells. Furthermore, the somatic cells (perhaps mesenchymal and/or epithelial cells), which respond to the stimulus via the PLAM of primordial germ cells, may differ in terms of the threshold for such a response between genetic males and females. This result suggests the mesenchymal and/or epithelial cells are not sexually predetermined, but rather that sexual determination follows the response to some signal(s) mediated by the PLAM. 相似文献
2.
Some reaction cascades in biological systems are analyzed by a self-organized chemical model, an autocatalytic reaction. This model is described by the coupling of a primary system which stabilizes the initial stage of the reaction rapidly and a partial system which controls the primary system slowly. By the internal force caused by a trigger above the threshold, the coupled system in near-equilibrium is broken and changed into a new state. From the rate equation for the coupled system, a dimensionless nonlinear state equation, n = -n3 - un - v, is derived, where n is the concentration of intermediate, and u, v are dynamic variables of the system. This equation is similar to a nonequilibrium tri-molecular reaction. By using this chemical network theory, fibrin polymerization. F + F----fm----fp + X, where F is a fibrinogen molecule, fm is a fibrin monomer, fp is fibrin polymer, and X is small peptides released from fibrinogen, is discussed as an excellent example of the enzyme reaction cascade. 相似文献
3.
Oka Kotaro; Ikeshima Hiroko; Ishikawa Hideo; Ohta Eiji; Sakata Makoto 《Plant & cell physiology》1988,29(5):771-775
We showed that the surface charge density of protoplasts canbe estimated by the 9-aminoacridine method. The estimated surfacecharge density of the protoplasts isolated from elongating regionsof Vigna mungo root was 39 ? 8 mC/m2. The negative surfacecharge density increased when protoplasts were treated withglutaraldehyde or when EDTA was added to the protoplast suspensionmedium. These results support the validity of our estimationof the surface charge density of protoplasts by the 9-aminoacridinemethod. The concentration of amino groups at the surface ofthe protoplasts was estimated to be 34 mC/m2. (Received June 19, 1987; Accepted April 11, 1988) 相似文献
4.
Kiyoshi Takahashi Katsuya Miyatani Hiroyuki Yanai Ho Jong Jeon Kotaro Fujiwara Tadashi Yoshino Kazuhiko Hayashi Tadaatsu Akagi Ken Tsutsui Koichi Mizobuchi 《Virchows Archiv. B, Cell pathology including molecular pathology》1992,62(1):105-113
Monocytic leukemia (MoL) cells were obtained from the peripheral blood of a patient in whom the leukemic cells infiltrating
various lymphoreticular organs exhibited features intermediate between interdigitating reticulum cells (IDC) and ordinary
phagocytic macrophages, whereas the leukemic cells in the peripheral blood were essentially monocytic and lacked such features.
Peripheral blood CD4+ T-cells were established as an interleukin-2-dependent T-cell line. When the MoL cells were exposed
for a few days to conditioned medium from the T-cell line, they extended several dendritic cytoplasmic projections and became
intensely positive for HLA-DR antigen, cytoplasmic S-100β protein, and CD1 antigen. Functionally, the conditioned medium significantly
down-regulated Fc-mediated and Fc-independent phagocytic activities, and the levels of lysosomal enzymes such as lysozyme
and nonspecific esterase in the MoL cells. Moreover, the conditioned medium significantly up-regulated the accessory cell
function of the MoL cells as measured by the primary allogenic mixed leukocyte reaction (MLR). Furthermore, the conditioned
medium significantly down-regulated the expression of CD14 antigen.
Biochemical analysis indicated that the factor responsible for these changes is a protein which is distinct from known human
cytokines and whose molecular weight is approximately 31 kDa. These findings suggest that IDC are closely related the monocytic
lineage and that helper T-cells play an important role in constructing the microenvironment of T-lymphoid tissues which is
necessary for the differentiation and maturation of IDC. 相似文献
5.
Ken-ichi Tanaka Shigeru Kohno Takashige Miyazaki Haruko Miyazaki Kotaro Mitsutake Shigefumi Maesaki Mitsuo Kaku Hironobu Koga 《Mycopathologia》1994,127(3):131-134
A latex agglutination test for cryptococcal antigen, the Eiken Latex test (Eiken, Tokyo, Japan), was compared with a monoclonal antibody-based agglutination assay, Pastorex® Cryptococcus (Diagnostics Pasteur, Marneur-la-Coquette, France). In a murine model of disseminated cryptococcosis, the kinetics of the antigen titers by the Eiken Latex were similar to those by the Pastorex® Cryptococcus, but sensitivity was much higher. In HIV-negative patients with pulmonary cryptococcosis, a cryptococcal antigen was detected in 6 of 10 patients by the Eiken Latex test and in only 3 of those patients by the Pastorex® Cryptococcus. The results indicate that the Eiken Latex is more sensitive for the detection of the cryptococcal antigen, even in non-disseminated cryptococcosis. The sensitivity and specificity of the Eiken Latex were examined using 195 sera from 25 patients with pulmonary cryptococcosis and 170 patients with non-cryptococcosis. The cutoff value of 1:8 showed a sensitivity of 76% (19/25) and a specificity of 98.9% (168/170). 相似文献
6.
Etsuro Ito Kotaro Oka Carlos Collin Bernard G. Schreurs Manabu Sakakibara Daniel L. Alkon 《Journal of neurochemistry》1994,62(4):1337-1344
Abstract: Tumor necrosis factor-a (TNF-α), interferon-γ (IFN-7), and interleukin-6 (IL-6), but not TNF-β, can induce the in vitro differentiation of the neuroblastoma cell line N103 in a dose-dependent manner. Differentiation of N103 was accompanied by the arrest of cell growth and neurite formation. The induction of neuroblastoma cell differentiation by TNF-α and IFN-γ can be specifically inhibited by a nitric oxide (NO) synthase inhibitor, l -NG -monomethylarginine. In contrast, the differentiation of N103 cells by IL-6 was not affected by l -NG -monomethylarginine. These results indicate that TNF-α and IFN-γ, but not IL-6, induce the differentiation of neuroblastoma cells via NO. This is confirmed by the finding that the culture super- natants of N103 cells induced by TNF-α and IFN-γ, but not that by IL-6, contained high levels of NO2 − , the production of which was inhibited by l - N G -monomethylarginine. Furthermore, the differentiation of N103 cells can be induced directly in a dose-dependent manner by the addition of nitroprusside, a generator of NO, into the culture medium. These data therefore indicate that NO may be an important mediator in the induction of neuronal cell differentiation by certain cytokines such as TNF-α and IFN-γ and that neuronal cells, in addition to the macrophagelike brain cells, can be induced by immunological stimuli to produce large quantities of NO. 相似文献
7.
Kan Shida Kotaro Takamizawa Masato Nagaoka Takao Tsuji Toshiaki Osawa 《Microbiology and immunology》1994,38(4):273-279
The binding of Escherichia coli heat-labile enterotoxin (LT) type I to glycosylated proteins with lactose (Galβ1-4Glc) by amino carbonyl reaction was studied by the Western blot assay and by the microtiter well binding assay. LT bound to a lactose-α-lactalbumin amino carbonyl product (Lac-LA), whereas cholera toxin did not. The binding ability of Lac-LA was abolished by β-galactosidase treatment, indicating that the terminal galactose is essential for the binding of LT. The binding of LT to Lac-LA was inhibited by galactose and lactose, and most effectively inhibited by lactulose (Galβ1-4Fru), which is a structural analog of the Amadori rearrangement product of the amino carbonyl reaction between lactose and an ε-amino group of a lysine residue (lactuloselysine). The results suggest that LT recognizes the portion of lactuloselysine in Lac-LA. LT also bound to a melibiose (Galα1-6Glc)-α-lactalbumin amino carbonyl product (Mel-LA), but the binding ability of Mel-LA was weaker than that of Lac-LA, suggesting that the β1-4 linked terminal galactose is dispensable but preferable for the binding. Furthermore, LT bound to the amino carbonyl products of lactose with β-lactoglobulin, caseins, bovine serum albumin, and ovalbumin. These results indicate that LT binds to the amino carbonyl products between proteins and sugars containing the terminal galactose, such as lactose. 相似文献
8.
9.
Yamato Kikkawa Kotaro Akaogi Hiroto Mizushima Naoki Yamanaka Makoto Umeda Kaoru Miyazaki 《In vitro cellular & developmental biology. Animal》1996,32(1):46-52
Summary Ladsin is a laminin-like cell-adhesive scatter factor with potent cell motility-stimulating ability and was purified from
serum-free conditioned medium of a malignant human gastric adenocarcinoma cell line STKM-1. To test its possible role in tumor
angiogenesis, we investigated its effect on primary culture of endothelial cells (human umbilical vein endothelial cells)
and endothelial cell line ECV304 in this study. Cell adhesion and motility effects of ladsin were observed in both types of
endothelial cells. In cell-attachment assay, ladsin interacted with integrin α3β1 that was expressed on the endothelial cell
surface. In Boyden chambers, ladsin stimulated both directed and random migration of ECV304 cells. Ladsin induced repair of
artificial wounds generated in ECV304 cell monolayers by stimulating cell migration. Ladsin did not affect the growth rate
of ECV304 cells at a low cell density but significantly increased the saturation cell density. These results suggest that
ladsin may be involved in the adhesion and migration of endothelial cells under some physiological and pathological conditions. 相似文献
10.
Phytochrome Control of Its Own Synthesis in Pisum sativum 总被引:1,自引:0,他引:1
Otto Veit; Sch?fer Eberhard; Nagatani Akira; Yamamoto Kotaro T.; Furuya Masaki 《Plant & cell physiology》1984,25(8):1579-1584
An analysis of phytochrome synthesis in Pisum seedlings by measuringthe activity of polysomal polyadenylated RNA (poly-A+-RNA) codingfor phytochrome apoprotein showed phytochrome control of itsown synthesis; brief red-light irradiation of pea seedlingsinhibited the activity of the RNA, and the red-light effectwas red/far-red reversible.
4 Permanent address: Biology Department, Faculty of Science,University of Tokyo, Hongo, Tokyo 113, Japan. (Received August 13, 1984; Accepted September 17, 1984) 相似文献