全文获取类型
收费全文 | 26369篇 |
免费 | 74篇 |
国内免费 | 101篇 |
专业分类
系统科学 | 127篇 |
丛书文集 | 290篇 |
教育与普及 | 46篇 |
理论与方法论 | 100篇 |
现状及发展 | 12732篇 |
研究方法 | 1090篇 |
综合类 | 11873篇 |
自然研究 | 286篇 |
出版年
2012年 | 351篇 |
2011年 | 603篇 |
2010年 | 138篇 |
2009年 | 134篇 |
2008年 | 383篇 |
2007年 | 442篇 |
2006年 | 463篇 |
2005年 | 458篇 |
2004年 | 521篇 |
2003年 | 417篇 |
2002年 | 460篇 |
2001年 | 781篇 |
2000年 | 766篇 |
1999年 | 522篇 |
1992年 | 474篇 |
1991年 | 372篇 |
1990年 | 414篇 |
1989年 | 380篇 |
1988年 | 369篇 |
1987年 | 410篇 |
1986年 | 435篇 |
1985年 | 548篇 |
1984年 | 423篇 |
1983年 | 363篇 |
1982年 | 360篇 |
1981年 | 369篇 |
1980年 | 372篇 |
1979年 | 906篇 |
1978年 | 770篇 |
1977年 | 655篇 |
1976年 | 587篇 |
1975年 | 616篇 |
1974年 | 797篇 |
1973年 | 632篇 |
1972年 | 689篇 |
1971年 | 813篇 |
1970年 | 1023篇 |
1969年 | 760篇 |
1968年 | 797篇 |
1967年 | 788篇 |
1966年 | 636篇 |
1965年 | 524篇 |
1964年 | 208篇 |
1959年 | 269篇 |
1958年 | 477篇 |
1957年 | 333篇 |
1956年 | 270篇 |
1955年 | 264篇 |
1954年 | 258篇 |
1948年 | 182篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
251.
252.
253.
The DNP fibres gamma-irradiated under aerobic condition showed a reduction of their diameter, while no remarkable changes were observed in the DNP fibres irradiated under hypoxic condition by scanning electron microscopy. 相似文献
254.
K Wlodarski 《Experientia》1976,32(12):1591-1592
The relative number of mast cells in the ear lobes' skin (pinna) of nude (athymic) nu/nu and normal (thymic) nu/+ heterozygotes of Balb/c mice was similar. The results obtained contradict some suggestions about the general influence of the thymus on the number of mast cells in the skin and suggest the existence of some local factor(s) in regulation of skin mast cell numbers. 相似文献
255.
V. R. Osório E Castro M. G. P. Vale A. P. Carvalho 《Cellular and molecular life sciences : CMLS》1976,32(4):424-426
Summary The effect of the antibiotic X-537A on the phosphorylated ATPase (EP) was investigated. The results show that X-537A depresses the level of EP which is dependent on the Ca2+ gradient, while the Ca2+-independent EP is not affected.
Acknowledgments. This work was supported by grants from the Instituto de Alta Cultura of the Portuguese Ministry of Education (No. CB/2) and the Calouste Gulbenkian Foundation. 相似文献
256.
G. M. Hanozet M. Simonetta D. Barisio A. Guerritore 《Cellular and molecular life sciences : CMLS》1976,32(10):1246-1249
Summary The three enzymes of ethanol metabolism alcohol dehydrogenase, aldehyde dehydrogenase and acetyl-CoA synthetase in the obligate aerobic yeastRhodotorula gracilis are repressed by glucose and induced by C2 metabolic fuels with a regulatory pattern indicating a correlation in the control mechanisms. To try an identification of the molecular signals involved in the transmission of the inducing stimulus, experiments were carried out by blocking with 2 mM pyrazole the ethanol acetaldehyde metabolic step. Results indicate that ethanol is not specifically required as a molecular signal for induction.This work was supported by a grant from the Italian Consiglio Nazionale delle Ricerche. 相似文献
257.
258.
M. Aušková K. Řežábek A. Černý M. Krajcrová M. Semonský 《Cellular and molecular life sciences : CMLS》1976,32(10):1310-1310
D-6-Methyl-8-[-isopropylaminoethyl] ergoline-I [VÚFB-10726], beginning from the dose of 0.05 mg/kg p.o., suppresses lactation through the inhibition of prolactin secretion in nursing rats. 相似文献
259.
Summary Rat brain mitochondria contain a significant proportion of poly(A) associated RNA which is higher than that found in microsomes from the same source. When steady state poly(A) RNA of brain mitochondria was analyzed by microelectrophoresis, it displayed a characteristic separation pattern with a large amount of free poly(A). 相似文献
260.
R. G. G. Andersson H. J. Arnqvist L. Lundholm 《Cellular and molecular life sciences : CMLS》1976,32(5):601-602
Summary The incorporation of leucice-14C into protein in bovine mesenteric arteries was augmented by cyclic GMP (10–3
M) and decreased by cyclic AMP (10–3
M). There was no effect of 5 AMP (10–3
M). The phosphodiesterase inhibiting drugs theophylline (10–3
M) and papaverine (5×10–5 g/ml) both decreased the leucine-14C incorporation.We are indebted to Mrs.Lena Burlin for hear assistance. Finacial support has been provided by the Swedish State Medical Research Council (No. 04X-101X-4498). 相似文献