全文获取类型
收费全文 | 1066070篇 |
免费 | 127489篇 |
国内免费 | 647篇 |
专业分类
1194206篇 |
出版年
2018年 | 8410篇 |
2016年 | 12213篇 |
2015年 | 18373篇 |
2014年 | 21095篇 |
2013年 | 29637篇 |
2012年 | 33794篇 |
2011年 | 33893篇 |
2010年 | 22825篇 |
2009年 | 21410篇 |
2008年 | 30536篇 |
2007年 | 31435篇 |
2006年 | 29099篇 |
2005年 | 28276篇 |
2004年 | 27818篇 |
2003年 | 26797篇 |
2002年 | 25938篇 |
2001年 | 45607篇 |
2000年 | 46053篇 |
1999年 | 37310篇 |
1998年 | 14514篇 |
1997年 | 15091篇 |
1996年 | 14507篇 |
1995年 | 13556篇 |
1994年 | 13432篇 |
1993年 | 13221篇 |
1992年 | 31062篇 |
1991年 | 30006篇 |
1990年 | 29496篇 |
1989年 | 28726篇 |
1988年 | 26387篇 |
1987年 | 25830篇 |
1986年 | 23730篇 |
1985年 | 23838篇 |
1984年 | 20033篇 |
1983年 | 17416篇 |
1982年 | 14013篇 |
1981年 | 12543篇 |
1980年 | 11881篇 |
1979年 | 19302篇 |
1978年 | 15386篇 |
1977年 | 14001篇 |
1976年 | 13252篇 |
1975年 | 14250篇 |
1974年 | 15398篇 |
1973年 | 15045篇 |
1972年 | 13576篇 |
1971年 | 12642篇 |
1970年 | 10799篇 |
1969年 | 10350篇 |
1968年 | 9210篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
951.
J. Dierschke T. Krüger F. Hüttmann F. Bairlein Kerstin Müller G. Scheiffarth H. -W. Helb W. Irsch W. Lantermann B. Haubitz W. Winkel und J. Haffer 《Journal of Ornithology》2003,144(4):484-498
Ohne Zusammenfassung 相似文献
952.
J De Coninck I Verdier-Denantes F Duyme S Bouquelet V Dumortier 《Journal of industrial microbiology & biotechnology》2000,25(1):58-61
Oxygen concentrations stimulated growth (maximum number of cells) and protease secretion by Tetrahymena thermophila. Agitation and aeration conditions for growth and protease secretion were optimised by a central composite design. The best
optimised combination was a stirrer speed of 338 rpm and an aeration of 1 vvm. Journal of Industrial Microbiology & Biotechnology (2000) 25, 58–61.
Received 24 September 1999/ Accepted in revised form 06 March 2000 相似文献
953.
954.
Conventional amperometric alcohol electrodes were constructed with oxygen- and hydrogen peroxide-base sensors and a much improved electrode was designed by placing a hydrophobic, gas-permeable membrane over the conventional hydrogen peroxide-based alcohol electrode. The immobilization of alcohol oxidase with glutaraldehyde was also studied and optimized. The upper linear ranges of the conventional and newly designed alcohol electrodes were 0.02 and 0.5% ethanol, respectively. The hydrophobic membrane of the new design eliminated the classical electrochemical interferences of hydrogen peroxide-based electrodes and the typical pH dependence of enzymatic systems. 相似文献
955.
Procedure and Analysis of a Useful Method in Determining Mycelial Dry Weights from Agar Plates 下载免费PDF全文
The evaluation of growth by dry weight determination of fungus mycelium for agar plates was examined. The data obtained were statistically analyzed. This method was shown to be sufficiently accurate to be used as an investigative tool. 相似文献
956.
LAWRENCE C. WATSON 《American anthropologist》1972,74(5):1189-1207
The results of this study indicate that urbanization has the effect of significantly altering the Guajiro's sense of ideal and feared identity. It was hypothesized that an attempt would be made to minimize dissonance between the ideal and the real or "true" self which the individual privately acknowledges. However, there is found to be considerable dissonance between ideal and real identities, with the latter actually including many components of feared identity. Defective socialization in the city is suggested as a possible reason for failure to achieve ideal standards. 相似文献
957.
958.
959.
960.
Externally attached radio transmitters do not affect the parental care behaviour of rock bass 总被引:2,自引:0,他引:2
S. J. Cooke 《Journal of fish biology》2003,62(4):965-970
Turning, pectoral fin and caudal fin rates and time spent on the nest of male rock bass Ambloplites rupestris , engaged in parental care, were not affected after the attachment of external radio transmitters. Reproductive success was similar between treatment and control fish. Micro external radio transmitters can be used on small fishes for studying parental care duration and post-care movement without altering their behaviour. 相似文献