全文获取类型
收费全文 | 2350篇 |
免费 | 222篇 |
出版年
2021年 | 28篇 |
2020年 | 16篇 |
2019年 | 18篇 |
2018年 | 25篇 |
2017年 | 32篇 |
2016年 | 51篇 |
2015年 | 65篇 |
2014年 | 90篇 |
2013年 | 123篇 |
2012年 | 104篇 |
2011年 | 99篇 |
2010年 | 81篇 |
2009年 | 69篇 |
2008年 | 106篇 |
2007年 | 115篇 |
2006年 | 108篇 |
2005年 | 90篇 |
2004年 | 87篇 |
2003年 | 65篇 |
2002年 | 78篇 |
2001年 | 86篇 |
2000年 | 93篇 |
1999年 | 87篇 |
1998年 | 32篇 |
1997年 | 36篇 |
1996年 | 20篇 |
1995年 | 30篇 |
1994年 | 36篇 |
1993年 | 20篇 |
1992年 | 57篇 |
1991年 | 50篇 |
1990年 | 64篇 |
1989年 | 57篇 |
1988年 | 51篇 |
1987年 | 47篇 |
1986年 | 42篇 |
1985年 | 34篇 |
1984年 | 22篇 |
1983年 | 20篇 |
1982年 | 25篇 |
1981年 | 15篇 |
1980年 | 13篇 |
1979年 | 29篇 |
1978年 | 25篇 |
1977年 | 15篇 |
1976年 | 13篇 |
1975年 | 19篇 |
1974年 | 19篇 |
1973年 | 12篇 |
1968年 | 9篇 |
排序方式: 共有2572条查询结果,搜索用时 62 毫秒
991.
H Sakuraba S Fujiwara T Noguchi 《Biochemical and biophysical research communications》1991,176(3):1450-1453
Alanine:glyoxylate aminotransferase has been reported to be present as the apo form in the peroxisomes and as the holo form in the mitochondria in chicken kidney. In contrast, the enzyme was found to be present as the holo form both in the peroxisomes and in the mitochondria in pigeon kidney, suggesting that birds are classified into two groups on the basis of intraperoxisomal form of kidney alanine:glyoxylate aminotransferase. In the kidney, the pigeon peroxisomal holo enzyme did not cross-react immunologically with the chicken peroxisomal apo enzyme. 相似文献
992.
T Azuma S Sato S Kitagawa S Hori S Kokudo T Hamaoka H Fujiwara 《Journal of immunology (Baltimore, Md. : 1950)》1989,143(1):1-8
C57BL/6 (B6) mice were i.v. presensitized with class I H-2-disparate B6-C-H-2bm1 (bm1) spleen cells. Such presensitization resulted in almost complete abrogation of bm1-specific Lyt-2+ T cell-mediated proliferative and IL-2-producing capacities as measured by MLC of lymphoid cells from presensitized B6 mice with stimulating bm1 cells. In contrast, comparable magnitude of CTL responses was generated in bulk cultures from presensitized B6 lymphoid cells to that obtained in unpresensitized B6 responding cultures. These differential influences of Lyt-2+ T cell functions were also demonstrated by limiting dilution assays; frequencies of proliferative and IL-2-producing T cell precursors were as low as undetectable in presensitized B6 lymphoid cells, whereas an appreciable frequency of CTL precursors in a portion of the same lymphoid cells was observed. When bm1 skin grafting was performed in B6 mice i.v. presensitized with bm1 cells, the strikingly prolonged survival of bm1 skin grafts was observed. It was also demonstrated that the bm1 skin graft-bearing B6 mice which had been presensitized with bm1 cells not only exhibited a continuing suppressive state of bm1-specific helper (proliferative and IL-2-producing) function but also failed to generate anti-bm1 CTL responses. These results indicate that 1) i.v. presensitization with class I H-2 alloantigens results in selective tolerance of Lyt-2+ Th cells which is adequate for inducing prolonged graft survival, 2) the induction of complete abrogation of CTL potential is not absolute requirement for the prolongation of graft survival, and 3) residual CTL potential is attenuated after grafting so far as Th cells are rendered tolerant. 相似文献
993.
Effects of specific alpha-adrenoceptive agents (alpha 1-agonist, alpha 1-antagonist, alpha 2-agonist and alpha 2-antagonist) on the extraneuronal accumulation of 3H-isoproterenol in the perfused rat heart were examined. The extraneuronal accumulation of 3H-isoproterenol in the hearts perfused with 3H-isoproterenol (10(-6)M) under COMT inhibition by tropolone (10(-4)M) was about 6 times higher than that of intact COMT. The increase in the accumulation by COMT inhibition was regarded as 100% and the effects of specific alpha-adrenoceptive agents on the accumulation was evaluated. alpha 1-agonists, methoxamine and phenylephrine, did not affect the accumulation. alpha 1-antagonists, prazosin, bunazosin and YM-12617, significantly decreased the accumulation of 3H-isoproterenol and these IC50 values were 2 x 10(-6)M, 3.5 x 10(-6)M and 2.3 x 10(-5)M, respectively. alpha 2-agonists, clonidine and guanabenz, significantly reduced the accumulation and these IC50 values were 3.4 x 10(-5)M and 2.9 x 10(-7)M, respectively. The alpha 2-antagonist, yohimbine, did not affect the accumulation. The present experiments clearly demonstrated that the tested alpha 1-antagonists and alpha 2-agonists inhibited uptake2 in rat heart but the tested alpha 1-agonists and an alpha 2-antagonist did not inhibit it. 相似文献
994.
S Araki S Abe S Ando K Kon N Fujiwara M Satake 《The Journal of biological chemistry》1989,264(33):19922-19927
A phosphonoglycosphingolipid, designated as FGL-IIb, was identified in nerve fibers of Aplysia kurodai by two-dimensional thin layer chromatography (Abe, S., Araki, S., and Satake, M. (1986) Biomed. Res. (Tokyo) 7, 47-51). FGL-IIb was isolated from the nervous system of A. kurodai by Iatrobeads column chromatography using three solvent systems. Pyruvic acid was identified by thin layer chromatography as its 2,4-dinitrophenylhydrazone and established by permethylation studies to be attached as a ketal to O-3 and O-4 of the terminal galactose of the oligosaccharide chain in FGL-IIb. By sugar analysis, permethylation studies, fast atom bombardment-mass spectrometry, and proton magnetic resonance spectrometry, the structure of FGL-IIb was concluded to be [3,4-O-(1-carboxyethylidene)]Gal beta 1----3GalNAc alpha 1----3(Fuc alpha 1----2) (2-aminoethylphosphonyl----6)Gal beta 1----4Glc beta 1----1ceramide. Its major aliphatic components were palmitic acid, octadeca-4-sphingenine and anteisononadeca-4-sphingenine. This is the first report of the occurrence of pyruvylated galactose as a constituent of animal sphingolipid. 相似文献
995.
H Fujiwara R B Levy G M Shearer 《Journal of immunology (Baltimore, Md. : 1950)》1981,126(4):1522-1525
Spleen cells from C3H/He mice immunized in vivo to trinitrophenyl (TNP)-self were sensitized in vitro to TNP-self. These spleen cells displayed strong lysis on TNP-modified H-2D end-matched (Kd-Dk) targets as well as enhanced cytotoxicity against H-2 matched (Kk-Dk) or H-2K end-matched (Kk-Dd) target cells. Cold target-blocking studies showed that the lysis of TNP-Kd-Dk targets could be blocked by the addition of TNP-modified Kk-Dk, Kk-Dd Kk-Db, or Kd-Dk, but not by TNP-modified Kd-Dd, Kb-Db and Kq-Kq spleen cells. These results demonstrate that the lysis of TNP-Kd-Dk targets is not due to cross-reactive clones against TNP-Kd-Dd, Kb-Db or Kq-Dq antigens. Inhibition of the TNP-Kd-Dk target lysis by TNP-Kk-matched (Kk-Dd or Kk-Db) as well as TNP-Dk-matched (Kd-Dk) blockers also reveals that this target is lysed by clones directed against shared antigens between Kk-TNP and Dk-TNP, indicating that no cytotoxic response restricted for Dk-TNP only could be detected even after in vivo priming. 相似文献
996.
Katsumi Niki Yumiko Takizawa Hiroaki Kumagai Ryoji Fujiwara Tatsuhiko Yagi Hiroo Inokuchi 《BBA》1981,636(2):136-143
The electrocatalytic activity of cytochrome c3 for the reduction of molecular oxygen was characterized from the studies of the adsorption of cytochrome c3 and the co-adsorption of cytochrome c3 with cytochrome c on the mercury electrode by the a.c. polarographic technique. The adsorption of cytochrome c3 on the mercury electrode is irreversible and is diffusion-controlled. The maximum amount of cytochrome c3 adsorbed was 0.92 · 10?11 mol · cm?2 at ?0.90 V. The amount of cytochrome c3 in the mixed adsorbed layer with cytochrome c was determined from the differential capacitance measurement. It was shown that the fractional coverage of cytochrome c3 can be estimated from its bulk concentration and the diffusion coefficient (1.05 · 10?6 cm2 · s?1). Cytochrome c3 catalyzes the electrochemical reduction of molecular oxygen from the two-electron pathways via hydrogen peroxide to the four-electron pathway at the mercury electrode in neutral phosphate buffer solution. The catalytic activity varies with the bulk concentration of cytochrome c3. The highest catalytic activity for the oxygen reduction (no hydrogen peroxide formation) is attained when one-half of the mercury electrode surface is covered by cytochrome c3. The addition of cytochrome c or bovine serum albumin to the cytochrome c3 solution inhibits the catalytic activity of cytochrome c3. The reversible polarographic behavior of cytochrome c3 through the mixed adsorbed layer of cytochrome c3 and cytochrome c was also investigated. 相似文献
997.
Adult male and female rats were inoculated with tween 80-ethylether-formalin-ultraviolet inactivated Sendai virus (Sv-V) and examined for the production of hemagglutination inhibition (HI) antibody. There were no significant differences in the antibody titers between males and females, and among the various routes of inoculation except for the intranasal which was not effective. The antibody became detectable 7 days after a single inoculation with 10(5) HAU of Sv-V. The antibody titer, which had its peak 21 days after the inoculation, persisted for 200 days and declined gradually thereafter. The HI antibody titers were correlated with inoculated Sv-V doses and a predominant booster reaction with the vaccine was observed. Maternal antibodies were detected in sucklings born to dams hyperimmunized with the vaccine. The titers were similar to those of the dams until 3 weeks after birth but declined rapidly after weaning at 4-week-old. The titers of fetuses and neonates before suckling were significantly lower than those of the sucklings. 相似文献
998.
The antibacterial property of 7 compounds, isolated from Erythrina variegata (Leguminosae) by repeated silica gel column chromatography, against cariogenic oral bacteria was investigated. Extensive spectroscopic study revealed that all were isoflavonoids. Among them, 3,9-dihydroxy-2,10-di(gamma,gamma-dimethylallyl)-6a,11a-dehydropterocarpan (erycristagallin) showed the highest antibacterial activity against mutans streptococci, other oral streptococci, Actinomyces and Lactobacillus species with a minimum inhibitory concentration (MIC) range of 1.56-6.25 microg/ml, followed by 3,6a-dihydroxy-9-methoxy-2,10-di(gamma,gamma-dimethylallyl)pterocarpan (erystagallinA) and 9-hydroxy-3-methoxy-2-gamma,gamma-dimethylallylpterocarpan (orientanol B) (MIC range: 3.13-12.5 microg/ml). The antibacterial effect of erycristagallin to mutans streptococci was based on a bactericidal action. Erycristagallin (6.25 microg/ml: MIC) completely inhibited incorporation of radio-labelled thymidine into Streptococcus mutans cells. Incorporation of radio-labelled glucose into bacterial cells was also strongly inhibited at MIC, and 1/2 MIC of the compound reduced the incorporation approximately by half. The findings indicate that erycristagallin has a potential as potent phytochemical agent for prevention of dental caries by inhibiting the growth of cariogenic bacteria and by interfering with incorporation of glucose responsible for production of organic acids. 相似文献
999.
Y. Otsu Y. Matsuda H. Shimizu H. Ueki H. Mori K. Fujiwara T. Nakajima A. Miwa T. Nonomura Y. Sakuratani Y. Tosa S. Mayama H. Toyoda 《Journal of Applied Entomology》2003,127(8):441-446
The chitinase secreting strain KPM‐012A of Alcaligenes paradoxus was isolated from tomato leaves and vitally entrapped in sodium alginate gel beads to provide a new method for biocontrol of phytophagous ladybird beetles Epilachna vigintioctopunctata. First, the peritrophic membrane was dissected from the adult ladybird beetles that ingested the suspension of KPM‐012A after starvation to observe degradation of the midgut surface by the bacteria under electron microscopy. The peritrophic membrane around the bacteria was degraded, suggesting the release of chitinase from the ingested bacteria. Large amounts of chitinase were successfully released from KPM‐012A‐entrapped calcium alginate beads. This chitinase release from the microbial beads was sustained for 1 week and was sufficient to digest the peritrophic membrane. Daily supply of tomato leaves treated with the microbial beads caused considerable suppression of leaf feeding and oviposition by the adult ladybird beetles, indicating that this method is effective for decreasing population of insect pests in the subsequent generation. Thus, the present study provided an experimental basis for the biocontrol measures of herbivorous insect pests by the chitinolytic bacteria entrapped in alginate beads. 相似文献
1000.
Akiko Fujiwara Katsunari Taguchi Ikuo Yasumasu 《Development, growth & differentiation》1990,32(3):303-314
Ryanodine, miconazole, clotrimazole, doxorubicin, quercetin, halothane, caffeine and chloroform, which activate Ca2+ -induced Ca2+ release from Ca2+ stores, induced Ca2+ release from a particulate fraction isolated from sea urchin eggs, Ca2+ influx into eggs and formation of a fertilization membrane in an appreciable number of eggs. Their minimum effective concentrations for inducing a fertilization membrane increased in the order of these drugs listed above, and this order was also the same as that of their minimum effective concentrations for inducing Ca2+ release from the isolated particulate fraction. Their effect in inducing a fertilization membrane was blocked by ruthenium red and procaine, which inhibit Ca2+ release from Ca2+ stores. Thus these drugs probably induced sufficient Ca2+ release to make the cytosolic Ca2+ level high enough in many eggs for formation of a fertilization membrane. In the absence of external Ca2+ , fewer eggs treated with these drugs formed a fertilization membrane and more eggs did so on further treatment with either A23187 or carbonylcyanide-p-trifluoromethoxy-phenylhydrazone (FCCP). Thus, a high level of Ca2+ is probably derived from Ca2+ release through Ca2+ releasing channels (by A23187), from mitochondria (by FCCP) and its transport from the external medium. 相似文献