全文获取类型
收费全文 | 16625篇 |
免费 | 41篇 |
国内免费 | 48篇 |
专业分类
系统科学 | 109篇 |
丛书文集 | 181篇 |
教育与普及 | 32篇 |
理论与方法论 | 94篇 |
现状及发展 | 7185篇 |
研究方法 | 833篇 |
综合类 | 7931篇 |
自然研究 | 349篇 |
出版年
2013年 | 128篇 |
2012年 | 308篇 |
2011年 | 618篇 |
2010年 | 124篇 |
2008年 | 350篇 |
2007年 | 331篇 |
2006年 | 360篇 |
2005年 | 370篇 |
2004年 | 348篇 |
2003年 | 312篇 |
2002年 | 295篇 |
2001年 | 475篇 |
2000年 | 452篇 |
1999年 | 325篇 |
1992年 | 280篇 |
1991年 | 212篇 |
1990年 | 231篇 |
1989年 | 225篇 |
1988年 | 225篇 |
1987年 | 222篇 |
1986年 | 215篇 |
1985年 | 305篇 |
1984年 | 248篇 |
1983年 | 169篇 |
1982年 | 179篇 |
1981年 | 167篇 |
1980年 | 188篇 |
1979年 | 444篇 |
1978年 | 332篇 |
1977年 | 340篇 |
1976年 | 318篇 |
1975年 | 342篇 |
1974年 | 419篇 |
1973年 | 401篇 |
1972年 | 411篇 |
1971年 | 464篇 |
1970年 | 604篇 |
1969年 | 508篇 |
1968年 | 546篇 |
1967年 | 490篇 |
1966年 | 423篇 |
1965年 | 318篇 |
1964年 | 125篇 |
1959年 | 183篇 |
1958年 | 308篇 |
1957年 | 209篇 |
1956年 | 195篇 |
1955年 | 156篇 |
1954年 | 188篇 |
1948年 | 146篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
91.
Summary Resting oxygen consumption of the vascularly isolated gracilis anticus muscle of the rat perfused by natural circulation via the femoral artery with diluted or undiluted blood depends on oxygen delivery (the product of flow rate and arterial oxygen concentration-DO2) only when DO2 falls below 16 l/min/g. 相似文献
92.
N. Michajlovskij V. Štrbák O. Földes 《Cellular and molecular life sciences : CMLS》1978,34(3):409-410
Summary The administration of thiocyanate to rats caused a significant increase of serum free thyroxine fraction, which coincided with the significant decrease of TSH level. The other components (AFT4, T4, T3) in serum at this time were decreased or unchanged. The finding suggests the role of free thyroxine fraction in feed-back regulation of TSH secretion.Acknowledgment. We thank Dr A. Parlow and the NIAMDD, Rat Pituitary Hormone Distribution Program, for material for rat TSH immunoassay; Dr J. Nauman (Inst. Postgrad. Med., Warsaw, Poland) for T3 antibody, and to Ing. J. Sadlo, Mrs M. t'astná and Miss R Fajkoová for technical assistance. 相似文献
93.
D Viala E Freton 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1980,291(6):573-576
In curarized Rabbits whose cervico-thoracic cord has been isolated through C2 and Th12 transections, a pharmacological activation (nialamide-DOPA) disclosed distinct rhythmic efferent activities, locomotor-like bursts in forelimb muscle nerves and "respiratory" discharges in the phrenic nerves: they originate respectively from a cervico-thoracic locomotion generator and from a "respiration" generator; these spinal generators appear to be interconnected with each other. 相似文献
94.
L. de Napoli E. Fattorusso Silvana Magno L. Mayol 《Cellular and molecular life sciences : CMLS》1981,37(11):1132-1132
Summary Furocaulerpin, an acetylenic sesquiterpenoid possessing a furan ring, has been isolated from the marine algaCaulerpa prolifera, and its stereostructure elucidated mainly on the basis of physico-chemical data.This work was carried out in the frame work of the Progetto Finalizzato per l'Oceanografia e i Fondi Marini, CNR, Rome. Thanks are due to the Centro di Metodologie Chimico-Fisiche of the University of Naples (Mr I. Giudicianni) for the determination of PMR-spectra. 相似文献
95.
Summary The concentrations of testosterone (T) and 5-dihydrotestosterone were measured in fluid collected from the rete testis of immature and adult rats. The results indicate that adult levels of T are attained in the seminiferous tubules much earlier than in the peripheral circulation.This work was performed at the Worcester Foundation for Experimental Biology, Shrewsbury, Massachusetts, USA and supported by the National Institutes of Health through grants HD12641 and HD12642. We thank Dr B.V. Caldwell for antiserum to testosterone. 相似文献
96.
E. Knecht J. Renau-Piqueras J. Hernández-Yago S. Grisolía 《Cellular and molecular life sciences : CMLS》1981,37(5):456-457
Summary Protein from resting or phytohemagglutinin-stimulated human peripheral blood T-lymphocytes, pulse-labeled in vitro for 1 h with3H-leucine, had a half-life of 30 h. 相似文献
97.
Summary Growth-promoting alpha-globulin (GPAG), a specific serum protein complex which induces mitotic activity in continually replicating metazoan cells in vitro, was shown in this study to support growth of astrocytes and mesenchymal cells as well as process formation of nerve cells isolated from cerebral hemispheres of chick embryos. 相似文献
98.
Summary In reserpinized mice the occurrence of goldthioglucose hypothalamic lesions was significantly lower than in control mice. Some protection was also conferred by serotonin-receptor blockers and by treatment with nialamide+DL--methyldopa, but the protective effect of reserpine was not reversed by serotonergic and dopaminergic agonists, alone or in combination, nor by insulin. 相似文献
99.
Summary -Galactosidase activity in intact cells of 21 species ofStreptomyces was measured using ONPG hydrolysis, without addition of a permeabilizing agent. Differences in the induction efficiency of ONPG-hydrolytic activity by lactose or galactose, which could have taxonomic implications, were observed among the species. 相似文献
100.
F. Bonneaux P. Labrude E. Dellacherie 《Cellular and molecular life sciences : CMLS》1981,37(8):884-886
Summary Stroma-free hemoglobin solutions present some drawbacks when used as blood substitutes, essentially because the hemoprotein has a low vascular retention, due to its small hydrodynamic volume. Covalent coupling of the protein with dextran derivatives artificially increases its size and affords polymeric conjugates whose oxygen-binding properties (Barcroft's curve, Hill coefficient) depend on the molecular weight.The authors wish to thank Prof. J. Neel and Prof. C. Vigneron for useful discussions and criticism. 相似文献