全文获取类型
收费全文 | 643篇 |
免费 | 31篇 |
国内免费 | 2篇 |
出版年
2021年 | 3篇 |
2018年 | 8篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 8篇 |
2014年 | 6篇 |
2013年 | 68篇 |
2012年 | 22篇 |
2011年 | 23篇 |
2010年 | 19篇 |
2009年 | 16篇 |
2008年 | 19篇 |
2007年 | 26篇 |
2006年 | 24篇 |
2005年 | 35篇 |
2004年 | 44篇 |
2003年 | 29篇 |
2002年 | 39篇 |
2001年 | 15篇 |
2000年 | 11篇 |
1999年 | 8篇 |
1998年 | 9篇 |
1997年 | 6篇 |
1996年 | 13篇 |
1995年 | 14篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 18篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 5篇 |
1981年 | 12篇 |
1980年 | 17篇 |
1979年 | 9篇 |
1978年 | 4篇 |
1977年 | 9篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1966年 | 3篇 |
1965年 | 4篇 |
1962年 | 3篇 |
1961年 | 3篇 |
1959年 | 2篇 |
排序方式: 共有676条查询结果,搜索用时 125 毫秒
21.
Restriction fragment length polymorphism of polymerase chain reaction (PCR) amplification products differentiated Rickettsia japonica, a causative agent of Oriental spotted fever, from other spotted fever group (SFG) rickettsiae. Primer pair Rr190. 70p and Rr190. 602n of R. rickettsii 190-kDa antigen gene sequence primed genomic DNAs obtained from R. japonica, type strain YH and strains NT, NK, YKI, and TKN. The products were cleaved by PstI but not by AfaI restriction endonuclease. The PstI digestion pattern of PCR-products amplified from all strains of R. japonica was identical and easily differentiated from that of other SFG rickettsiae. The present study demonstrated a genotypic difference between R. japonica and other pathogenic SFG rickettsiae. 相似文献
22.
Kajiwara Hideyuki; Okuyama Tsuneo; Fukuda Minoru; Hirano Hisashi; Oono Kiyoharu 《Plant & cell physiology》1992,33(1):27-32
A protein with relatively high homology in its N-terminal aminoacid sequence to animal parvalbumin and oncomodulin has beenidentified in leaves of rice (Oryza sativa L.). The PV-likeprotein has a relative molecular mass of 27,000 and an isoelectricpoint of 5.0. This protein was partially purified by ion-exchangechromatography, and the purified protein was found to have Ca2+-bindingactivity in a microscale Ca2+-binding assay. Furthermore, anantiserum raised against a synthetic oligopeptide based on theN-terminal amino acid sequence of this protein cross-reactedwith protein not only from rice but also from other monocotyledonousplants. (Received October 17, 1990; Accepted October 17, 1991) 相似文献
23.
Specimens of basidiomes and/or rhizomorphs ofArmillaria mellea complex and basidiomes ofRhodophyllus abortivus, developing on the same decaying stumps or stems of forest trees, were collected in three forests in Hokkaido. Normal basidiomes
ofR. abortivus were found near to, but free from, the rhizomorphs and/or basidiomes ofArmillaria, while abnormal basidiomes, as carpophoroid forms, were developed on the rhizomorphs ofArmillaria. Of three mycoparasiticArmillaria isolates found withR. abortivus, one was identified asA. gallica and two asA. jezoensis. The isolates ofR. abortivus showed excellent mycelial growth and rhizomorph formation on PDA. However, on MDA, RMDA and BMDA, they showed poor aerial
mycelia growth and no rhizomorphs. In the contrapositional cultures, the growth ofA. gallica was completely inhibited byR. abortivus on PDA but only slightly inhibited on MDA and RMDA. On the other hand, mutual inhibition at a distance was observed on BMDA.
The mycelial growth and rhizomorph formation inA. jezoensis were severely inhibited by the colony ofR. abortivus on PDA, but only slightly inhibited on MDA. On RMDA and BMDA, the colonies of twoArmillaria species andR. abortivus showed mutual inhibition at a distance and apparent rhizomorph formation by bothArmillaria species. 相似文献
24.
Kunio Koshimura Yasutaka Takagi Soichi Miwa †Tsuneo Kido ‡Yasuyoshi Watanabe Yoshio Murakami Yuzuru Kato Tomoh Masaki 《Journal of neurochemistry》1995,65(2):827-830
Abstract: 6R-l -erythro-Tetrahydrobiopterin (6R-BH4) is a cofactor for aromatic l -amino acid hydroxylases and nitric oxide synthase. Recently, we have reported that independently of its cofactor activities, 6R-BH4 acts from the outside of neurons in the brain to enhance the release of monoamine neurotransmitters such as dopamine. To characterize the pharmacological properties of the action, we examined the effects of 6S-BH4, a diastereoisomer of 6R-BH4, on dopamine release in the rat striatum by using brain microdialysis and compared its effects with those of 6R-BH4. Perfusion of 6S-BH4 or 6R-BH4 through the dialysis probe increased extracellular dopamine levels (an index of in vivo dopamine release) concentration dependently; the maximal increase by 6S-BH4, was one-sixth of that by 6R-BH4. 6S-BH4 increased extracellular DOPA levels in the presence of NSD 1015, an inhibitor of aromatic l -amino acid decarboxylase (an index of in vivo tyrosine hydroxylase activity), to an extent similar to the increase induced by 6R-BH4. The increase in the DOPA levels induced by either of the pteridines was abolished after pretreatment of rats with α-methyl-p-tyrosine (an inhibitor of tyrosine hydroxylase). Under the same conditions, the 6S-BH4-induced dopamine release was abolished, but most of the 6R-BH4-induced increase persisted. Coadministration of 6S-BH4 with 6R-BH4 inhibited the increase in dopamine release induced by 6R-BH4 alone. These results show that 6R-BH4 stimulates dopamine release by acting at the specific recognition site on the neuronal membrane, and that 6S-BH4 acts as an antagonist of 6R-BH4 at this site, although it has cofactor activities. 相似文献
25.
Hiromi Takahashi-Iwanaga Toshihiko Iwanaga Yuzuru Sakamoto Tsuneo Fujita 《Cell and tissue research》1995,280(3):491-497
In previous ultrastructural studies we have shown that at the tip of intestinal villi in guinea pigs, effete enterocytes are separated into two portions: a thin apical cytoplasm to be exfoliated into the lumen and a major basal portion to be ingested by lamina propria macrophages. During this process, intraepithelially disposed, large granular lymphocytes interdigitate with enterocytes in a complex manner. In the present study, the relation between the enterocytes and the lymphocytes in the villous epithelium of the guinea pig small intestine is described by use of transmission and scanning electron microscopy in an attempt to visualize the roles and activities of the lymphocytes more clearly. The lymphocytes project numerous pointed processes into effete enterocytes, even piercing them. Enterocytes are deeply indented or perforated, probably as a result of the encroaching lymphocyte processes. Some enterocytes are separated into apical and basal portions by numerous large excavations in the cytoplasm. These findings indicate that repeated perforating penetration of the lymphocytes induces cell cleavage. Supporting this supposition, our microcinematographic observations demonstrate the alternate protrusion and withdrawal of processes of lymphocytes. The processes advance with a pointed end, and subsequently, retract with a rounded end in a cycle of 8–18 seconds. 相似文献
26.
In a survey of 186 randomly selected microbial strains isolated from composted manure, 63 transformed oleic acid into three types of products: hydroxy fatty acid, fatty amide, and less polar oleyl lipid. Selection of oleic acid-transforming microorganisms was enhanced in nutrient agar supplemented with 0.1% (vol/vol) oleic acid at pH 7.2. Most of the 63 diverse isolates elicited inconsistent and poorly reproduced transformations. However, strains 142b (NRRL B-14797) transformed oleic acid to 10-hydroxystearic acid consistently, and strain 229b (NRRL B-14812) produced an octadecenamide. Taxonomic studies indicated that NRRL strain B-14797, possessing 1,3-dihydroxy-2-amino-15-methylhexadecane and sphinganine bases, was closely related to Sphingobacterium thalpophilum, and NRRL B-14812 was identified as Bacillus cereus. 相似文献
27.
Sixteen strains of aerobic bacteria which contain bacteriochlorophyll a were isolated from the samples collected in aerobic marine environments: thalli of Enteromorpha linza, Porphyra sp., Sargussum horneri; beach sand; and the surface seawater from Aburatsubo Inlet. When they occurred, their proportions among the aerobic heterotrophic populations ranged from 0.9 to 1.1% in the seaweed samples and from 1.2 to 6.3% in the beach sand samples and were 0.9% in the seawater sample. The results suggested that the aerobic photopigmented bacteria widely inhabit aerobic marine environments. 相似文献
28.
Takashi Manabe Tsuneo Okuyama Akiko Suzuki Akiyo Shigematsu 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1981,225(1):65-71
The changes in rat plasma protein distribution after carbon tetrachloride administration were examined using two-dimensional electrophoresis, utilizing isoelectric focusing in polyacrylamide gel in the first dimension and pore gradient polyacrylamide gel electrophoresis in the second dimension. Drastic changes in amount of protein were observed at more than 20 spot positions including those of transferrin, Gc-globulin and low-density lipoprotein. The time course of the changes was examined, and the most drastic changes were observed at 2 days after carbon tetrachloride administration. 相似文献
29.
Stipe elongation during basidiocarp maturation in Coprinus macrorhizus: Mechanical properties of stipe cell wall 总被引:1,自引:0,他引:1
Stipe elongation during basidiocarp maturation in the wild-type,#5026+5132, and the elongationless mutant, NG0398, of Coprinusmacrorhizus was studied, and the following results were obtained.
- In the wild-type the middle zone of the stipe elongated 8.4times in 15 hr during maturation, while in the mutant it elongatedoaiy 2.2 times.
- Component cells of the stipe elongated inparallel with thestipe elongation in both the wild-type andthe mutant. The widthof stipe cells was almost constant duringelongation in thewild-type, while it increased 2 times in themutant. Cell volumeincreased ca. 8 times in both stocks.
- Theosmotic value of stipe cells was almost constant (0.450.50M) throughout elongation of both the wild-type and the elongationlessstipes.
- Mechanical properties of the cell wall were examinedby measuringshrinkage, extensibility and minimum stress-relaxationtime(To) of the stipe during maturation. These parameters weredirectlyproportional to the elongation rate to follow.
- Whenthe wild-type stipes were incubated in various concentrationsof mannitol solution and then in plain buffer solution, theextensibility of the stipe after the incubation in mannitolsolutions changed proportionally with the stipe length afterthe mannitol treatment, and To with the elongation capacityin plain buffer solution.
30.
Pretreatment of Chang liver cells with (0.5 or 1 mM) stimulated Na+-independent uptake of leucine at low concentrations (?1 mM). The stimulatory effect of on the uptake of leucine measured in Na+-replete medium was completely blocked by the addition of (5 mM), which shows that the L system participates in the stimulation. The Na+-dependent uptake of glycine was depressed by pretreatment. The stimulation of the Na+-independent component of leucine uptake continued for at least 30 min after treatment, while the inhibition of glycine uptake was progressive with time and the Na+-dependent uptake of leucine became depressed later, after the treatment. It has been demonstrated that treatment of cells with is capable of increasing the Na+-independent influx of leucine and at the same time slightly decreasing the efflux of it. These results suggest that attacks the Na+-independent system of amino acid transport at the reactive SH groups(s) of relevant protein(s) in favor of specific activation of that system in this cell. 相似文献