全文获取类型
收费全文 | 235篇 |
免费 | 29篇 |
出版年
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 6篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 13篇 |
2015年 | 9篇 |
2014年 | 11篇 |
2013年 | 14篇 |
2012年 | 12篇 |
2011年 | 15篇 |
2010年 | 9篇 |
2009年 | 10篇 |
2008年 | 7篇 |
2007年 | 5篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 9篇 |
2003年 | 9篇 |
2002年 | 7篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1998年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 8篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1969年 | 1篇 |
1962年 | 1篇 |
1961年 | 4篇 |
1959年 | 1篇 |
1957年 | 1篇 |
1956年 | 1篇 |
1950年 | 1篇 |
1931年 | 1篇 |
排序方式: 共有264条查询结果,搜索用时 421 毫秒
151.
A possible active segment on the inactive human X chromosome 总被引:6,自引:0,他引:6
An idic(Xp-) in which the two X chromosomes are attached short arm to short arm, and which thus has two b regions (the Q-dark segment next to the centromere on Xp) between the inactivation centers, assumed to be situated on the Q-dark region next to the centromere on Xq, showed 63.8% bipartite Barr bodies as compared with 22.2% formed by idic(Xq-). In addition, the mean distance of the two parts of the Barr bodies in the fibroblasts of a patient with idic(Xp-) is significantly greater than in the cases with one or no b region. Contrary to the other patients with abnormal X chromosomes, the buccal cells of a woman idic(Xp-) showed a number of bipartite Barr bodies. — To explain these observations we have put forward the hypothesis that the b region on the Xp always remains active and thus, when the rest of the chromosome forms a Barr body, this segment is extended, allowing the two parts of the X chromatin to get farther apart and at the same time increasing the percentage of bipartite bodies. 相似文献
152.
S. Biondi S. Fornalé K. M. Oksman-Caldentey M. Eeva S. Agostani N. Bagni 《Plant cell reports》2000,19(7):691-697
Jasmonic acid (JA) and its methyl ester (MeJA) at concentrations ranging from 0.001 to 10 μM provoked large increases in
methylputrescine levels in normal and hairy roots of Hyoscyamus muticus L.; generally, levels of free putrescine and perchloric acid-soluble conjugated putrescine, spermidine and spermine also
increased dramatically. More 14C-putrescine was formed when hairy roots were incubated with labelled ornithine than with arginine; conjugated 14C-putrescine was also rapidly formed. In accord with these results, ornithine decarboxylase (EC 4.1.1.17) activity was higher
than that of arginine decarboxylase (EC 4.1.1.19), and MeJA enhanced these activities about two- and fourfold, respectively.
Although treatment of root cultures with jasmonates enhanced precursor (putrescine, methylputrescine) levels and accumulation
of secondary metabolites such as acid-soluble conjugated di-/polyamines, it provoked only modest increases in tropane alkaloid
tissue levels.
Received: 24 March 1999 / Revision received: 5 October 1999 / Accepted: 26 October 1999 相似文献
153.
Mitogen-activated protein kinase phosphatase 1 (MKP-1) expression is induced by inflammatory factors, and it is an endogenous suppressor of inflammatory response. MKP-1 expression is increased by PDE4 inhibitor rolipram suggesting that it is regulated by cAMP-enhancing compounds. Therefore, we investigated the effect of β2-receptor agonists on MKP-1 expression and inflammatory response. We found that β2-receptor agonists salbutamol and terbutaline, as well as 8-Br-cAMP, increased MKP-1 expression. Salbutamol and terbutaline also inhibited p38 MAPK phosphorylation and TNF production in J774 mouse macrophages. Interestingly, salbutamol suppressed carrageenan-induced paw inflammation in wild-type mice, but the effect was attenuated in MKP-1(-/-) mice. In conclusion, these data show that β2-receptor agonists increase MKP-1 expression, which seems to mediate, at least partly, the observed anti-inflammatory effects of β2-receptor agonists. 相似文献
154.
Eeva-Liisa Hintikka Leena Saari Seija Berg Aldo Rizzo Eeva Karppanen 《Mycotoxin Research》1987,3(1):28-31
In 1985 82 samples of feed and food grain were analyzed for trichothecenes deoxynivalenol (DON), nivalenol (NV), diacetoxyscirpenol (DAS), T-2 toxin, HT-2 toxin and fusarenon-X (F-X). Trichothecenes were found in 77 of these samples. The highest amounts were DON 6300 ug/kg and DAS 1680 ug/kg.In 1986, in a corresponding study of 113 samples, trichothecenes were found in 110 samples. A new trichothecene in Finland, 3-acetyldeoxynivalenol (3-AcDON), was identified in 35 of these samples in concentration of 2–211 ug/kg.Analyzing methods were gas chromatography and GC-mass spectrometry. It is characteristic of the feed samples suspected of causing outbreaks in animals in Finland that several trichothecenes are often found in the same sample. As an example of this is a poultry feed with following results: DON 33 ug/kg, 3-AcDON 21 ug/kg, DAS 45 ug/kg, T-2 toxin 40 ug/kg, HT-2 toxin 12 ug/kg. 相似文献
155.
We studied nestling growth, growth abnormalities, mortality and breeding success of two hole-nesting passerines, the great tit (Parus major) and the pied fly-catcher (Ficedula hypoleuca), at 14 study sites around a copper smelter complex in Harjavalta, south-west Finland in 1991–1993. The main pollutants in the area are heavy metals and sulphuric oxides. Exposure of birds to heavy metals was shown by measuring their faecal concentrations. Copper, nickel and lead contents of nestling faeces were high near the factory and decreased with distance away from the pollution source. F. hypoleuca nestlings suffered high mortality very close to the factory complex, but did relatively well at all other sites. Breeding success of P. major was below background levels up to 3–4 km from the pollution source and nestlings grew poorly close to the factory. Growth abnormalities of legs and wings in F. hypoleuca nestlings were significantly more common near the factory than farther away. In contrast, F. hypoleuca nestlings grew equally well at all distances. The poor breeding success of F. hypoleuca close to the factory complex is probably related to the high amount of heavy metals in its diet, and low availability of calcium-rich food items may enhance this effect. We suggest that the poor breeding success of P. major is related to habitat changes that have taken place around the factory. The different responses of these two bird species are probably due to their different diet. Our results show convincingly that species-specific differences in response should be carefully considered when planning schemes for air pollution monitoring. 相似文献
156.
157.
158.
159.
Background
Previous studies of the natural history of alpha-1-antitrypsin (AAT) deficiency are mostly based on highly selected patients. The aim of this study was to analyse the mortality of PiZZ individuals.Methods
Data from 1339 adult PiZZ individuals from the Swedish National AAT Deficiency Registry, followed from 1991 to 2008, were analysed. Forty-three percent of these individuals were identified by respiratory symptoms (respiratory cases), 32% by liver diseases and other diseases (non-respiratory cases) and 25% by screening (screened cases). Smoking status was divided into two groups: smokers 737 (55%) and 602 (45%) never-smokers.Results
During the follow-up 315 individuals (24%) died. The standardised mortality rate (SMR) for respiratory cases was 4.70 (95% Confidence Interval (CI) 4.10-5.40), 3.0 (95%CI 2.35-3.70) for the non-respiratory cases and 2.30 (95% CI 1.46-3.46) for the screened cases. The smokers had a higher mortality risk than never-smokers, with a SMR of 4.80 (95%CI 4.20-5.50) for the smokers and 2.80(95%CI 2.30-3.40) for the never-smokers. The Rate Ratio (RR) was 1.70 (95% CI 1.35-2.20). Also among the screened cases, the mortality risk for the smokers was significantly higher than in the general Swedish population (SMR 3.40 (95% CI 1.98-5.40).Conclusion
Smokers with severe AAT deficiency, irrespective of mode of identification, have a significantly higher mortality risk than the general Swedish population. 相似文献160.