全文获取类型
收费全文 | 580篇 |
免费 | 30篇 |
专业分类
610篇 |
出版年
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 5篇 |
2016年 | 12篇 |
2015年 | 28篇 |
2014年 | 28篇 |
2013年 | 33篇 |
2012年 | 38篇 |
2011年 | 31篇 |
2010年 | 19篇 |
2009年 | 14篇 |
2008年 | 33篇 |
2007年 | 41篇 |
2006年 | 34篇 |
2005年 | 26篇 |
2004年 | 31篇 |
2003年 | 24篇 |
2002年 | 20篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 12篇 |
1998年 | 10篇 |
1997年 | 13篇 |
1996年 | 8篇 |
1995年 | 13篇 |
1994年 | 11篇 |
1993年 | 13篇 |
1992年 | 8篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1981年 | 2篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1967年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有610条查询结果,搜索用时 0 毫秒
131.
Yasuhiro Hashimoto Mikiko Abe Akemi Suzuki Kentaro Iwasaki Tamio Yamakawa 《Glycoconjugate journal》1985,2(3-4):255-265
Genetic polymorphism in the expression of the GM1(NeuGc) ganglioside has been shown in the liver of inbred strains of mice. Through analysis of the gangliosides of H-2 congenic and recombinant strains, this polymorphism was demonstrated to be controlled by a locus mapped left outside of the H-2 complex on chromosome 17, and the locus was assumed to control the level of the activity of GM1(NeuGc) synthetase, UDP-galactose:GM2(NeuGc) galactosyltransferase (E.C.2.4.1.62) [Hashimotoet al., J Biochem (1983) 94:2049-54].In the present study we analyzed the genetic linkage between the activity of the galactosyltransferase and the H-2 haplotype. For this purpose, we selected two inbred strains of mice, WHT/Ht and BALB/c, because they have different levels of the transferase activity and show different H-2 haplotypes; the specific activity of the transferase obtained with BALB/c was one-eighth of that with WHT/Ht, and BALB/c expressed the la.7 antigen as one of the products encoded in their H-2d complex, whereas WHT/Ht did not. To analyze the linkage between these two phenotypes, WHT/Ht were mated with BALB/c to obtain the F1 mice, and the female F1 mice were then backcrossed to WHT/Ht. It was found that one half of the backcross generation expressed the la.7 antigen derived from BALB/c and had a significantly lower specific activity of the transferase than that of WHT/Ht, while the other half did not express the la.7 antigen but had the same specific activity of the transferase as that obtained with WHT/Ht.These results suggest that the locus controlling the level of the transferase activity in mouse liver is linked to the H-2 complex on chromosome 17.Abbreviations NeuGc
N-glycolylneuraminic acid
The ganglioside nomenclature is based on the system of Svennerholm, J Neurochem (1963) 10:613-23. The sialic acid species present is shown in parentheses after the ganglioside abbreviation. 相似文献
132.
The clinically isolated heat labile enterotoxin (LT)-producing strains of Escherichia coli can be separated into two groups, namely spontaneous LT-releasing strain and non-spontaneous LT-releasing strain, based on their phenotypes of spontaneous release of LT into the culture medium. The phenotype of spontaneous LT release was observed to correlate closely with the phenotype of the release of numerous small vesicles into the culture medium. Both morphological and biological examinations of the vesicle showed that the vesicle was released from the outer membrane. It can, therefore, be assumed that LT may be released from the cell at the time the vesicles form. 相似文献
133.
Sun Nyunt Wai Tohru Takata Akemi Takade Naotaka Hamasaki Kazunobu Amako 《Archives of microbiology》1995,164(1):1-6
We purified an iron-containing protein from Campylobacter jejuni using ultracentrifugation and ion-exchange chromatography. Electron microscopy of this protein revealed circular particles
with a diameter of 11.5 nm and a central core with a diameter of 5.5 nm. The protein was composed of a single peptide of 21
kDa and did not serologically cross-react with horse spleen ferritin. The UV-visible spectrum of the protein showed no absorption
peaks in the visible region, indicating that little or no heme is bound. The ratio of Fe:phosphate of C. jejuni ferritin was 1.5:1. From these morphological and chemical examinations, we concluded that the C. jejuni purified protein is a ferritin of the same class as that of Helicobacter pylori and Bacteroides fragilis and differs from the heme-containing bacterioferritin of Escherichia coli. The 30 N-terminal amino acids were sequenced and were found to resemble the sequences of other ferritins strongly (H. pylori ferritin, 73% identity; B. fragilis ferritin, 50% identity; E. coli gene-165 product, 50% identity), and to a lesser degree, bacterioferritins (E. coli bacterioferritin, 26% identity; Azotobacter vinelandii, 26% identity; horse spleen ferritin 30% identity). Proteins that cross-reacted with antiserum against the ferritin of C. jejuni were found in other Campylobacter species and in H. pylori, but not in Vibrio, E. coli, or Pseudomonas aeruginosa.
Received: 6 September 1994 / Accepted: 6 February 1995 相似文献
134.
Summary The influence of colchicine on the addition of 3H-galactose to the enamel protein in secretory amelloblasts of cultured germs of rat molar tooth was investigated by light- and electron-microscopic radioautography. In tooth germs cultured without colchicine, the reaction products of 3H-galactose were observed over Golgi cisternae at early chase times and then localized over the enamel with time. In tooth germs cultured with colchicine, the silver grains were seen over the Golgi cisternae, condensing granules and accumulated secretory granules. Some grains also appeared with time over the pale granular material precipitated in the intercellular space with colchicine treatment. In quantitative analysis with light microscopic radioautography, values of silver grain counts over the unit area (100 m2) on ameloblasts and enamel of colchicine-treated tooth germs were significantly lower at both 0 min and 30 min chase after 30 min pulse than those of control tooth germs, respectively. This finding indicates that colchicine diminished the incorporation of 3H-galactose into the secretory ameloblast of cultured tooth germs. It is suggested that colchicine decreases the activity of the Golgi apparatus with regared to the addition of sugar to the synthesizing glycoprotein in the secretory ameloblast. 相似文献
135.
Summary We found cells with calcitonin gene-related peptide-like immunoreactivity and with many cored vesicles in the secretory portions of sweat glands of rat foot pads. About 10% of sweat glands contained single immunoreactive cells. The immunoreactive cells were flaskshaped, with a narrow apex facing the glandular lumen and the bulk of the cell body in the basal half of the glandular wall. In the cytoplasm, there were many vesicles, 100–250 nm in diameter, with cores of various electron densities. These cytochemical and cytological characteristics suggest that the immunoreactive cells are homologous to gastrointestinal basal granulated cells. 相似文献
136.
Intact cells of Halobacterium halobium R1mR, a red strain deficient in bacteriorhodopsin, pumped protons only in an inward direction when illuminated, in contrast to R1 cells which showed proton transfer in both directions. The cellular ATP level of R1mR, as well as R1 cells, under nitrogen, was increased upon illumination to the aerobic level. The proton uptake and ATP synthesis observed with both R1 and R1mR occurred even after the majority of bacteriorhodopsin (in R1) had been bleached with NH2OH, but they were abolished by brief heat treatment of the cells. These results suggest a mechanism common to both strains which is responsible for the observed proton uptake and ATP synthesis. When R1mR cells were grown in the presence of nicotine, an inhibitor of carotenoid biosynthesis, both the proton uptake and ATP synthesis were completely depressed, but recovered after all-trans retinal was added externally. The action spectrum by R1mR, NH2OH-treated R1, or nicotinegrown R1mR reconstituted with retinal consistently exhibited a maximum between 580 and 600 nm. Hence the mechanism is independent of bacteriorhodopsin of the purple membrane. Instead, our results indicate the possible presence of a new chromoprotein which involves retinal as the chromophore and participates in the mechanism of cellular ATP synthesis. 相似文献
137.
Mating behaviour and associated songs were compared between 2 sympatric congeneric species,Nezara antennata andN. viridula, between which interspecific mating was known to occur under natural conditions. The fundamental sequence of mating behaviour
for these species was the same. Three kinds of songs were recorded from each sex ofN. antennata. ForN. viridula, 4 kinds of male songs and 3 kinds of female songs were recorded. The songs which corresponded with definite behavioural
bouts were distinct between these species. Some consideration was made as to why interspecific differences in the songs did
not sufficiently engender ethological isolation. In addition, some geographic variations in the songs were shown among Yugoslavian
(Čokl et al. 1972), American (Harris et al. 1982) and Japanese populations ofN. viridula. These variations were relatively inconspicuous when compared with the interspecific differences fromN. antennata. 相似文献
138.
M Iwase M Kikuchi K Nunoi Y Maki M Wakisaka M Wada M Fujishima 《Endocrinologia japonica》1988,35(6):803-808
We have evaluated the residual pancreatic B cell function by glucagon load test in 28 patients with non-insulin-dependent diabetes mellitus (NIDDM) of a duration of 20 years or more. The increase in serum C-peptide at 6 minutes after glucagon administration (delta C-peptide) was used as an index of residual B cell function. There was much less delta C-peptide in patients treated with insulin than in those treated with sulfonylurea (p less than 0.05), and it was significantly correlated with the body mass index (r = 0.40, p less than 0.05). Long term metabolic control assessed by the average annual mean fasting blood glucose for the observation period (mean, 21 years) was not correlated with delta C-peptide (r = -0.13). The prevalence of retinopathy which needed photocoagulation therapy and of neuropathy in patients with poor residual B cell function (delta C-peptide less than or equal to 0.3 ng/ml) was the same as that in those with good residual B cell function (delta C-peptide greater than or equal to 1.0 ng/ml). The present study shows that the residual B cell function is not correlated with long term glycemic control and the prevalence of diabetic complications in long-standing NIDDM patients. 相似文献
139.
The localization of calcium in the enamel organ of rapidly-frozen, freeze-substituted rat incisors in early-stage amelogenesis was examined by a histochemical calcium-staining method. In secretory ameloblasts, glyoxal bis(2-hydroxyanil) (GBHA) staining revealed intense red reactions in mitochondria and tubulovesicular structures located throughout the cytoplasm, while no reaction was seen in the nucleus and cytosol, nor along the plasma membranes of the respective cells. No significant GBHA reaction was observed in the intercellular compartment and other cells of the enamel organ. Some granular reactions were localized in the cells of the adjacent connective tissue. Control tests confirmed the specificity of GBHA reactions for calcium. Thus, the present observations provide histochemical evidence indicating an exclusive localization of calcium in mitochondria and tubulovesicular structures of the secretory ameloblast, and support their contributions to the translocation of calcium from the proximal to the distal pole of the cytoplasm. 相似文献
140.