全文获取类型
收费全文 | 1258篇 |
免费 | 65篇 |
专业分类
1323篇 |
出版年
2022年 | 16篇 |
2021年 | 28篇 |
2020年 | 16篇 |
2019年 | 13篇 |
2018年 | 22篇 |
2017年 | 14篇 |
2016年 | 28篇 |
2015年 | 45篇 |
2014年 | 47篇 |
2013年 | 71篇 |
2012年 | 73篇 |
2011年 | 64篇 |
2010年 | 62篇 |
2009年 | 53篇 |
2008年 | 71篇 |
2007年 | 66篇 |
2006年 | 47篇 |
2005年 | 60篇 |
2004年 | 71篇 |
2003年 | 52篇 |
2002年 | 52篇 |
2001年 | 13篇 |
2000年 | 14篇 |
1999年 | 21篇 |
1998年 | 12篇 |
1997年 | 8篇 |
1996年 | 11篇 |
1995年 | 12篇 |
1994年 | 8篇 |
1993年 | 15篇 |
1992年 | 13篇 |
1991年 | 10篇 |
1990年 | 17篇 |
1989年 | 13篇 |
1987年 | 14篇 |
1985年 | 7篇 |
1984年 | 13篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1980年 | 13篇 |
1979年 | 7篇 |
1976年 | 9篇 |
1975年 | 10篇 |
1974年 | 7篇 |
1973年 | 11篇 |
1972年 | 8篇 |
1971年 | 6篇 |
1970年 | 8篇 |
1969年 | 6篇 |
1962年 | 6篇 |
排序方式: 共有1323条查询结果,搜索用时 0 毫秒
1.
2.
D B Snead A Weltman J Y Weltman W S Evans J D Veldhuis M M Varma C D Teates E A Dowling A D Rogol 《Journal of applied physiology》1992,72(6):2149-2156
We examined the relationships among reproductive hormone concentrations and bone mineral density (BMD) in 43 women runners classified as eumenorrheic (n = 24), oligomenorrheic (n = 8), or amenorrheic (n = 11). Results were compared with a eumenorrheic nonrunner control group (n = 11). Serum 17 beta-estradiol, progesterone, and dehydroepiandrosterone sulfate concentrations were determined in daily blood samples for 21 days, and integrated concentrations (areas under the curve) were calculated. BMD was assessed at the lumbar spine and proximal femur by dual-photon absorptiometry. As expected, 17 beta-estradiol, progesterone, and lumbar spine BMD were higher in the control and eumenorrheic runner groups than in the oligomenorrheic and amenorrheic runner groups (P less than 0.05). Progesterone concentration was significantly correlated with lumbar spine BMD in the eumenorrheic runners (r = 0.61). None of the steroid hormones was significantly related to BMD in the oligomenorrheic/amenorrheic group. The present data suggest that circulating levels of gonadal steroid hormones affect axial BMD in eumenorrheic runners. 相似文献
3.
4.
5.
Summary Studies on the effect of different levels of sucrose in the slurry of peat-based Rhizobium inoculant on germination, seedling growth, and rhizosphere fungi of peanut and soybean revealed that the limits of tolerance for good germination were 2.5 and 5 per cent of the sugar, respectively. Fusaria and aspergilli were invariably present at all levels of sucrose whereas species of Penicillium, Myrothecium, Cunninghamella and Curvularia were isolated only from the rhizosphere at higher levels of the sugar 相似文献
6.
Hypocotyl segments, 5 to 8 mm length from 4 to 7 day old seedlings, callused on B5 medium supplemented with Kn (0.5 ppm) and NAA (0.1 ppm). Even without transfer, shoots were formed in such cultures. About 20% of the cultures produced multiple shoots. In medium with 1 ppm each of Kn and NAA direct shoots were formed at one end of the hypocotyl segment and callusing was initiated at the other end. The plants obtained in either medium formed roots and could be transferred to soil for further growth.Abbreviations BA
benzyladenine
- 2,4-D
2,4-dichlorophenoxy acetic acid
- GA3
gibberellic acid
- Kn
Kinetin
- NAA
naphthalene acetic acid 相似文献
7.
When incubated in high galactose media, fibroblasts from individuals with the severe (Mediterranean) variety of glucose-6-phosphate dehydrogenase (G6PD) deficiency accumulate significantly less galactitol than do fibroblasts from matched control subjects. The effect is not observed in fibroblasts from black subjects with the more common, and milder, A- variant of G6PD deficiency. Since aldose reductase and sorbitol dehydrogenase activities in experimental and control fibroblasts are identical, the effect is most likely due to the substantial reduction in NADPH levels in severely G6PD-deficient cells. Sorbitol does not accumulate either in control or in G6PD deficient fibroblasts incubated in high glucose medium, most likely because of the action of sorbitol dehydrogenase, and the presence of a carrier-mediated glucose transport system in the cell membrane which limits the concentration of glucose that can accumulate in these cells. 相似文献
8.
9.
Summary The incorporation of [35S]sulphate was followed into the washed cell suspensions of Nitrosomonas europaea. Thus bound sulphate, sulphite, sulphide, cysteine, glutathione, homocysteine and methionine were found in the ethanol soluble fraction as well as in the residual hydrolysed protein fraction. Cysteic acid, methionine sulphoxide and methionine sulphone were detected in the residual protein. The reaction between sulphydryl groups and N-ethylmaleimide has been successfully used to stabilize the thiol compounds in cell-extracts and the derivatives thus obtained were separated by paper chromatography. As in other microorganisms, sulphate is first activated by ATP in Nitrosomonas before it is reduced. The formation of APS and PAPS has been studied. A pathway for the incorporation of [35S]sulphate is proposed.Abbreviations POPOP
1,4-bis-(5-phenyloxazolyl-2)-benzene
- PPO
2,5-diphenyloxazole
- APS
adenosine-5-phosphosulphate
- PAPS
adenosine-3-phosphate 5-phosphosulphate
- ATP
adenosine triphosphate
- DNA-ase
deoxyribonuclease
- NEM
N-ethylmaleimide
- TCA
trichloro-acetic acid
- GSH
glutathione 相似文献
10.
Enzymatic labeling of nucleic acids is a fundamental tool in molecular biology with virtually every aspect of nucleic acid
hybridization technique involving the use of labeled probes. Different methods for enzymatic labeling of DNA, RNA and oligonucleotide
probes are available today. In this review, we will describe both radioactive and nonradioactive labeling methods, yet the
choice of system for labeling the probe depends on the application under study. 相似文献