全文获取类型
收费全文 | 120篇 |
免费 | 2篇 |
专业分类
122篇 |
出版年
2024年 | 2篇 |
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 7篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 4篇 |
2013年 | 10篇 |
2012年 | 2篇 |
2011年 | 5篇 |
2010年 | 3篇 |
2009年 | 3篇 |
2008年 | 7篇 |
2007年 | 3篇 |
2006年 | 4篇 |
2005年 | 3篇 |
2004年 | 1篇 |
2003年 | 3篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有122条查询结果,搜索用时 15 毫秒
71.
Improved method for ribonuclease zymogram 总被引:1,自引:0,他引:1
An improved method for ribonuclease zymogram in agarose overlays is described which enables significantly enhanced sensitivity and the avoidance of false-positive activity. Two critical aspects of the zymogram method—the fixation/staining technique and the RNA substrate concentration—were evaluated for the RNase activity in RNase A and in human serum and urine. The zymogram method is sensitive to at least 10 pg of RNase A and does not show a false-positive reaction from 1500 μg of non-RNase protein following electrophoresis in thin-layer polyacrylamide gel. 相似文献
72.
PurposeTo evaluate patient-level colorectal cancer outcomes in relation to residential income and racial segregation and composition of the neighborhood surrounding the diagnosing hospitals, and characterize presence of cancer-relevant diagnosis and treatment modalities that might contribute to these associations.MethodsWe utilized Georgia state cancer registry data (2010–2015), matching diagnosis information to hospital technology provided by the American Hospital Association and spatial information to the US Census. We modeled time-to-treatment and survival time, using Cox proportional hazards models, stratified by segregation. Segregation was examined as residential economic and racial evenness (Atkinson index) and isolation (isolation index) and mean income at the Census tract level. To assess possible contributing factors, analysis of hospital diagnosis and treatment technologies in relation to segregation was conducted.ResultsAverage income of the Census tract and racial residential segregation of the diagnosing hospital’s neighborhood was generally unassociated with time-to-treatment or survival time. Higher income evenness around the diagnosing hospital was associated with shorter time-to-treatment, with no association with time-to-death. Higher income isolation for the diagnosing hospital, conversely, was associated with longer times to treatment, but also longer survival times. Hospitals in regions with higher level of residential income segregation were less likely to have a particular diagnosing or treatment technologies, such as virtual colonoscopy and chemotherapy.ConclusionHospital resources may be a function of their immediate economic environment, and this may have influence on cancer outcomes. Future work should evaluate patient outcomes in light of technologies or therapies utilized within particular economic environments. 相似文献
73.
R. N. Inserra N. Vovlas A. P. Nyczepir E.J. Wehunt A. M. Golden 《Journal of nematology》1990,22(1):45-55
Most morphological characteristics of three populations of a Tylenchulus sp. from peach roots in Alabama, Arkansas, and Georgia did not differ from those of T. palustris paratypes. However, some mature females differed slightly from those of T. palustris paratypes from Florida. These mature females were more swollen in the posterior portion of their bodies, and they possessed digitate postvulval body sections with round rather than conoid termini. These morphological variants had a wide postvulval section core (PVSC), as do T. palustris paratypes; they did not differ from the paratypes in other characteristics. Second-stage juveniles and males were less morphologically variable and were not different from the paratypes. No males were found in populations from Alabama and Georgia. The Tylenchulus sp. from three peach sites was determined to be T. palustris. This is the first report of T. palustris on an economically important crop. 相似文献
74.
To determine the threshold doses of testosterone propionate (TP) that cause clear-cut behavioral changes in the sexual behavior of castrated male cynomolgus monkeys, observations were made on three males during successive 5-week treatment periods while they received daily subcutaneous doses of 100 μg TP increasing in octaves to 25.6 mg TP. Males were tested with each of the same two ovariectomized, estrogen-treated females (6 pairs, 330 1-hr behavior tests). To mimic the diurnal plasma testosterone rhythm, TP injections were given at 1600 hr and blood samples were obtained at 0800 hr (141 samples). Male ejaculatory activity increased at the threshold dose of 200 μg TP per day giving plasma testosterone levels of 830 ng/100 ml, which is in the physiological range of 600–1600 ng/100 ml for intact males. This threshold dose was eight times higher than in rhesus monkeys on a dose per kilogram body weight basis. There was a further marked increase in ejaculatory performance at higher doses (6.4 to 25.6 mg) giving supraphysiological plasma levels of 4000–9000 ng/100 ml. There were individual differences in the behavioral changes occurring with TP treatment, and the female partner modulated the effects. These findings were generally similar to those obtained with male rhesus monkeys, but certain species differences were noted. 相似文献
75.
A method for the preparation of radioactive estradiol-17 beta, 17-glucosiduronate by incubating 3H-estradiol with rhesus monkey liver microsomal preparation in the presence of uridine diphosphoglucuronic acid is described. Small but significant amounts of the conjugate were also obtained from the 150,00 pellet and cytosol fractions. The addition of NADPH to the incubation media increased the yield of radioactive-estradiol-17 beta, 17-glucosiduronate perhaps by preserving the integrity of the C-17-hydroxyl group. As expected, the effect of the reduced nucleotide was more pronounced in the fractions other than the microsome. The biosynthesized conjugate was isolated and purified by multiple column chromatography and the structure was confirmed by derivative formation, enzyme hydrolysis and crystallization of the aglycone. 相似文献
76.
As it had been shown that sodium butyrate promoted hyperacetylation of nuclear histones the effect of 5, 10, and 50 mM sodium butyrate on the synthesis of Hb FIc (an acetylated component of Hb F) and Hb F in cord blood reticulocytes was studied. The presence of 5 mM butyrate showed a significant increase in the production of Hb FIc, whereas Hb F synthesis was unaffected. Higher concentrations of butyrate, however, had no stimulatory effect on Hb FIc synthesis. Results of pulse-chase studies indicated that sodium butyrate inhibited the turnover of preformed Hb FIc, probably by inhibiting deacetylase. 相似文献
77.
78.
79.
Yeast enolase binds one mole of 113Cd2+ per subunit at a site that consists of all oxyligands in a distorted octahedral environment. This "conformational" metal ion's environment undergoes further distortion on addition of substrate/product or analogs. At pH's below the optimum value the shifted resonance tends to break up into several, suggesting the existence of several slowly exchanging intermediate forms. At acid pH's, on addition of one additional mole/subunit of 113Cd2+, which greatly increases catalysis, "conformational" resonance(s) further broadens, suggesting that the second, "catalytic" metal ion increases the rates of interconversion between "conformational" species. At more alkaline pH's, near the optimum pH, the "conformational" peak is sharpened, which suggests that very fast interconversion is occurring. The position of the "catalytic" metal ion resonance also suggests all oxyligands in a distorted octahedral geometry. The "catalytic" resonance is often broadened to the point where it cannot be seen, suggesting rapid changes in its geometry due to interconversion of substrate and product. 相似文献
80.
Direct radioimmunoassay are described for the measurement of each of three specific estrogen glucosiduronates: estrone glucosiduronate, 17 beta-estradiol-17-glucosiduronate and estriol-16 alpha-glucosiduronate in urine. Each assay utilizes a specific antiserum prepared by complexing the carboxylic acid group of the appropriate glucosiduronate to the epsilon-amino group of lysine in bovine serum albumin or bovine thyroglobulin. The antisera showed little or no cross reactivity toward other estrogens that might be present in significant amounts in urine. These antisera were used for the direct assay of the conjugates in urine from normal men and nonpregnant women without prior extraction or chromatography. The values were similar to those obtained after extraction, chromatographic purification on DEAE-Sephadex and subsequent immunoassay; The following mean values +/- SE (microgram/g creatinine) were obtained: estrone glucosiduronate, male 10.1 +/- 0.6, follicular phase female 17.3+/- 1.6, luteal phase female 31.8 +/- 2.5; 17 beta-estradiol-17-glucosiduronate, male 1.7 +/- 0.3, follicular phase female 2.4 +/- 0.1, luteal phase female 4.2 +/- 0.4; estriol-16 alpha-glucosiduronate, male 1.8 +/- 0.2, follicular phase female 4.7 +/- 0.9, luteal phase female 10.0 +/- 1.6. 相似文献