全文获取类型
收费全文 | 1396篇 |
免费 | 117篇 |
专业分类
1513篇 |
出版年
2022年 | 9篇 |
2021年 | 17篇 |
2020年 | 10篇 |
2019年 | 11篇 |
2018年 | 11篇 |
2017年 | 18篇 |
2016年 | 30篇 |
2015年 | 35篇 |
2014年 | 35篇 |
2013年 | 87篇 |
2012年 | 72篇 |
2011年 | 63篇 |
2010年 | 49篇 |
2009年 | 58篇 |
2008年 | 61篇 |
2007年 | 79篇 |
2006年 | 58篇 |
2005年 | 49篇 |
2004年 | 65篇 |
2003年 | 60篇 |
2002年 | 55篇 |
2001年 | 60篇 |
2000年 | 54篇 |
1999年 | 37篇 |
1998年 | 18篇 |
1997年 | 19篇 |
1996年 | 13篇 |
1995年 | 9篇 |
1994年 | 15篇 |
1993年 | 15篇 |
1992年 | 34篇 |
1991年 | 21篇 |
1990年 | 23篇 |
1989年 | 18篇 |
1988年 | 29篇 |
1987年 | 18篇 |
1986年 | 19篇 |
1985年 | 8篇 |
1984年 | 13篇 |
1983年 | 13篇 |
1981年 | 9篇 |
1980年 | 13篇 |
1979年 | 13篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1976年 | 11篇 |
1975年 | 10篇 |
1974年 | 12篇 |
1973年 | 10篇 |
1969年 | 7篇 |
排序方式: 共有1513条查询结果,搜索用时 15 毫秒
61.
Ono N Nakashima K Schipani E Hayata T Ezura Y Soma K Kronenberg HM Noda M 《The Journal of biological chemistry》2007,282(35):25509-25516
Multiple signaling pathways participate in the regulation of bone remodeling, and pathological negative balance in the regulation results in osteoporosis. However, interactions of signaling pathways that act comprehensively in concert to maintain bone mass are not fully understood. We investigated roles of parathyroid hormone receptor (PTH/PTHrP receptor) signaling in osteoblasts in unloading-induced bone loss using transgenic mice. Hind limb unloading by tail suspension reduced bone mass in wild-type mice. In contrast, signaling by constitutively active PTH/PTHrP receptor (caPPR), whose expression was regulated by the osteoblast-specific Col1a1 promoter (Col1a1-caPPR), suppressed unloading-induced reduction in bone mass in these transgenic mice. In Col1a1-caPPR transgenic (Tg) mice, hind limb unloading suppressed bone formation parameters in vivo and mineralized nodule formation in vitro similarly to those observed in wild-type mice. In addition, serum osteocalcin levels and mRNA expression levels of type I collagen, Runx2 and Osterix in bone were suppressed by unloading in both wild-type mice and Tg mice. However, in contrast to unloading-induced enhancement of bone resorption parameters in wild-type mice, Col1a1-caPPR signaling suppressed, rather than enhanced, osteoclast number and osteoclast surface as well as urinary deoxypyridinoline excretion upon unloading. Col1a1-caPPR signaling also suppressed mRNA expression levels of RANK and c-fms in bone upon unloading. Although the M-CSF and monocyte chemoattractant protein 1 (MCP-1) mRNA levels were enhanced in control Tg mice, these levels were suppressed in unloaded Tg mice. These results indicated that constitutive activation of PTH/PTHrP receptor signaling in osteoblastic cells suppresses unloading-induced bone loss specifically through the regulation of osteoclastic activity. 相似文献
62.
Miyata Seiko Otake Hironao Fujishiro Hiroshige Iwamoto Kunihiro Noda Akiko Sone Michihiko Ozaki Norio 《Sleep and biological rhythms》2022,20(3):403-411
Sleep and Biological Rhythms - Sleep problems and obstructive sleep apnea (OSA) increase with age and disturb life in old age. Positional therapy is one option to treat OSA, but the differences in... 相似文献
63.
We present a simple model to assess the quantum yield of photochemistry (ΦP) and CO2 assimilation rate from two parameters that are detectable by remote sensing: chlorophyll (chl) fluorescence and the photochemical reflectance index (PRI). ΦP is expressed as a simple function of the chl fluorescence yield (ΦF) and nonphotochemical quenching (NPQ): ΦP = 1–bΦF(1 + NPQ). Because NPQ is known to be related with PRI, ΦP can be remotely assessed from solar‐induced fluorescence and the PRI. The CO2 assimilation rate can be assessed from the estimated ΦP value with either the maximum carboxylation rate (Vcmax), the intercellular CO2 concentration (Ci), or parameters of the stomatal conductance model. The model was applied to experimental data obtained for Chenopodium album leaves under various environmental conditions and was able to successfully predict ΦF values and the CO2 assimilation rate. The present model will improve the accuracy of assessments of gas exchange rates and primary productivity by remote sensing. 相似文献
64.
Yoko Ono Atsuko Noda Yasuhiro Zaima Narumi Jitsufuchi Seijo Eto Hiroshi Noda 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1996,677(2):339
In comparison with the hepatocytes obtained from intact rats and rats pretreated with phenobarbital or 3-methylchoranthrene, the amount of isonicotinic acid (INA) formed from isoniazid (INH) increased substantially after incubation at 37°C using the pretreated hepatocytes. This suggests an oxidative pathway for INA formation from INH, apart from hydrolysis. In order to explore the exact mechanism of INA formation in the hepatocytes, an HPLC assay for INA in the presence of INH and acetylisoniazid was developed. In this assay, INA was extracted after the preparation of an ion pair with tetra-n-butylammonium hydroxide, and analysed using an ODS column and a mobile phase consisting of 0.067 M potassium dihydrogenphosphate solution-methanol (96:4 v/v). The method is simple, accurate and especially suitable for INA determination after incubation of INH in isolated rat hepatocytes. 相似文献
65.
Pseudomonas putida IFO13696, a recombinant strain with dsz desulfurization genes, desulfurized dibenzothiophene (DBT) in water but not in n-tetradecane. By introducing into this recombinant strain the hcuABC genes that take part in the uptake of DBT in the oil phase into the cell, 82% of 1 mM DBT in n-tetradecane was degraded in 24 h by resting cells. The products of hcuABC genes thus acted in the uptake of DBT in n-tetradecane into the cells and were effective in desulfurization of DBT in the hydrocarbon phase. 相似文献
66.
Kashiwagi K Shiba K Fukami-Kobayashi K Noda T Nishikawa K Noguchi H 《Journal of biochemistry》2003,133(3):371-376
The family of periplasmic binding proteins (PBPs) is believed to have arisen from a common ancestor and to have differentiated into two types. At first approximation, both types of PBPs have the same fold pattern, reflecting their common origin. However, the connection between the main chains of a type 2 PBP is more complicated than a type 1 PBP's. We have been interested in the possibility that such structural changes affect the folding of PBPs. In this study, we have characterized the folding pathways of MglB (a type 1 PBP) and ArgT (a type 2 PBP) by using urea gradient gel electrophoresis, fast protein size-exclusion liquid chromatography and hydrophobic dye ANS binding assay. We found a distinct difference in folding between these two proteins. The folding of MglB followed a simple two-state transition model, whereas the folding of ArgT was more complicated. 相似文献
67.
We examined the metabolism of N-desisopropylpropranolol (NDP), which is generated from propranolol (PL) by side-chain N-desisopropylation, to naphthoxylactic acid (NLA) in rat liver. S(-)-NDP (S-NDP) and R(+)-NDP (R-NDP) were enantioselectively metabolized to NLA in isolated rat hepatocytes and in an enzyme reaction system of rat liver mitochondria with cofactor NAD+. Furthermore, the clearance profiles of NDP enantiomers were examined in an enzyme reaction system of rat liver mitochondria without NAD+. The amounts of S-NDP remaining in the incubation medium were similar to those of R-NDP, suggesting that monoamine oxidase (MAO) catalyzes the deamination of NDP to the aldehyde intermediate, but fails to deaminate enantioselectively S-NDP or R-NDP. Cyanamide, a potent inhibitor of aldehyde dehydrogenase (ALDH), markedly decreased the formation of NLA from racemic NDP in the enzyme reaction system of rat liver mitochondria with NAD+. When rat liver cytosol and microsomes were added to this enzyme reaction system, no significant alterations were observed in the amount of NLA generated from racemic NDP. We concluded that MAO deaminates NDP to an aldehyde intermediate, and that mitochondrial ALDH subsequently catalyzes the enantioselective metabolism of the aldehyde intermediate to NLA in rat liver. 相似文献
68.
Katsumi Mizuta Chieko Abiko Yoko Aoki Tatsuya Ikeda Tsutomu Itagaki Fumio Katsushima Yuriko Katsushima Yoko Matsuzaki Masahiro Noda Hirokazu Kimura Tadayuki Ahiko 《Microbiology and immunology》2012,56(12):855-858
To clarify the epidemiology of viral acute respiratory infections (ARIs), 305 human parainfluenza virus types 1 (HPIV1), 154 HPIV2 and 574 HPIV3 strains were isolated from 16,962 nasopharyngeal swabs obtained between 2002 and 2011 at pediatric clinics in Yamagata, Japan. The total isolation frequency for HPIV1–3 was 6.1%. Unlike HPIV1 infections, HPIV3 showed clear seasonality with yearly outbreaks in the spring–summer season. HPIV2 tended to appear biannually in autumn–winter. Although no reliable techniques for the laboratory diagnosis of these infections have been established, the present results suggest that HPIV1–3 are an important causative agent of ARIs in children. 相似文献
69.
Galactolipids and phospholipids rapidly accumulated in a whole seed between 2 and 4 days after germination. However, the rate of incorporation of [14C] acetate into galactolipids was very low. The predominant fatty acid of galactolipids was linolenic acid, while those of phospholipids were linoleic and palmitic acids. Fatty acids of monogalactosyldiacylglycerol in germinating safflower seeds were randomly distributed between the 1 - and 2-positions of the glycerol molecule and the distribution in digalactosyldiacylglycerol was slightly non-random, while fatty acids of galactolipids in mature safflower leaves were non-randomly distributed. Triacylglycerol was synthesized in the cotyledon tissue of the germinating seeds simultaneously with its rapid degradation. In addition, lipid biosynthesis in protoplasts is described. 相似文献