全文获取类型
收费全文 | 5466篇 |
免费 | 18篇 |
国内免费 | 36篇 |
专业分类
系统科学 | 34篇 |
丛书文集 | 60篇 |
教育与普及 | 5篇 |
理论与方法论 | 21篇 |
现状及发展 | 2652篇 |
研究方法 | 269篇 |
综合类 | 2409篇 |
自然研究 | 70篇 |
出版年
2012年 | 79篇 |
2011年 | 157篇 |
2010年 | 39篇 |
2008年 | 117篇 |
2007年 | 139篇 |
2006年 | 119篇 |
2005年 | 106篇 |
2004年 | 112篇 |
2003年 | 97篇 |
2002年 | 115篇 |
2001年 | 164篇 |
2000年 | 177篇 |
1999年 | 108篇 |
1996年 | 40篇 |
1992年 | 94篇 |
1991年 | 77篇 |
1990年 | 73篇 |
1989年 | 66篇 |
1988年 | 53篇 |
1987年 | 70篇 |
1986年 | 70篇 |
1985年 | 129篇 |
1984年 | 77篇 |
1983年 | 68篇 |
1982年 | 60篇 |
1981年 | 61篇 |
1980年 | 69篇 |
1979年 | 131篇 |
1978年 | 125篇 |
1977年 | 136篇 |
1976年 | 121篇 |
1975年 | 140篇 |
1974年 | 147篇 |
1973年 | 110篇 |
1972年 | 106篇 |
1971年 | 151篇 |
1970年 | 229篇 |
1969年 | 151篇 |
1968年 | 138篇 |
1967年 | 166篇 |
1966年 | 124篇 |
1965年 | 82篇 |
1964年 | 48篇 |
1959年 | 69篇 |
1958年 | 82篇 |
1957年 | 82篇 |
1956年 | 52篇 |
1955年 | 48篇 |
1954年 | 54篇 |
1948年 | 41篇 |
排序方式: 共有5520条查询结果,搜索用时 203 毫秒
761.
I V Yannas 《Nature》1970,227(5265):1358-1360
762.
763.
764.
V Faublée C Boulard 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1980,290(13):911-914
Anaphylactic antibodies were demonstrated in cattle parasitized by Hypoderma sp. Using a technic of passive cutaneous anaphylaxy in Goats. 相似文献
765.
M. A. Marcialis P. La Colla M. L. Schivo O. Flore A. Firinu B. Loddo 《Cellular and molecular life sciences : CMLS》1975,31(4):502-503
Résumé Par passage en série sur des cellules en culture et en présence de 5-iodo-2-desoxyuridine (IUdR) on a obtenu une souche de virus herpétique résistant à l'IUdR. Cette souche est très peu virulente chez la souris et le lapin, mais est capable de protéger ces animaux contre le virus pathogène d'origine.
This work has been supported by a Grant of Consiglio Nazionale delle Ricerche, Roma. 相似文献
This work has been supported by a Grant of Consiglio Nazionale delle Ricerche, Roma. 相似文献
766.
J R Claude V N Huyen J M Warnet F Blanc 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1975,281(9):599-604
Wistar rats were fed, during 56 weeks, a diet containing 5 g/kg of Aramite. At the end of the treatment, all the surviving animals show, on anatomo-pathological examination, malignant proliferation of the hepatic tissue and, in certain cases, of biliary ducts. This compound, proposed in the past as acaricide in agriculture, can thus be considered as a model substance for induction of malignant liver tumors. 相似文献
767.
768.
M. B. Mattock V. S. Sheorain D. Subrahmanyam 《Cellular and molecular life sciences : CMLS》1978,34(3):304-305
Summary Feeding to mice of both basal as well as high sucrose diet led to increased levels of plasma triglycerides, which was associated with increased lecithin-cholesterol acyltransferase activity. Although males had significantly higher LCAT activity than females in all the dietary groups, sex difference in the plasma triglycerides was observed in high sucrose group only. Increase in plasma triglycerides in experimental groups was associated with an increase in LCAT activity. 相似文献
769.
Direct expression in Escherichia coli of a DNA sequence coding for human growth hormone. 总被引:33,自引:0,他引:33
D V Goeddel H L Heyneker T Hozumi R Arentzen K Itakura D G Yansura M J Ross G Miozzari R Crea P H Seeburg 《Nature》1979,281(5732):544-548
DNA coding for human growth hormone was constructed by using chemically synthesised DNA in conjunction with enzymatically prepared cDNA. This 'hybrid' gene was expressed in Escherichia coli under the control of the lac promoter. A polypeptide was produced having the size and immunological properties characteristic of mature human growth hormone. 相似文献
770.
An embryo protein induced by SV40 virus transformation of mouse cells 总被引:17,自引:0,他引:17
A specific protein of molecular weight (MW) approximately 55,000 (55K) was found recently by immunoprecipitation in all SV40 virus-transformed mammalian cells, in addition to the SV40 large T antigen (appoximately 94K) and small antigen (approximately 17K), which are the only proteins coded by the 'early half' of the SV40 genome. The 55K protein is encoded by cellular DNA; its peptide pattern is different from that of the SV40 antigens and it is species specific in mouse, rat, hamster, monkey and human SV40-transformed (or infected) cells. A 55K protein with a similar peptide pattern was found in mouse embryonal carcinoma cells not exposed to SV40. Similar proteins were reported in mouse sarcomas and leukaemias induced by a great variety of aetiological agents and also in a spontaneously transformed mouse fibroblast cell line, and it has been suggested that the protein may be a general correlated of cellular tumorigenicity. We now report that the approximately 55K protein is present in primary cell cultures from 12-14 day old mouse embryos, but not in 16-day old mouse embryos. The embryo protein has a peptide pattern virtually indistinguishable from that of the SV40-induced protein. We also show by comparing closely related cell families that spontaneously transformed highly tumorigenic mouse cells do not possess the 55K protein. 相似文献