全文获取类型
收费全文 | 27020篇 |
免费 | 59篇 |
国内免费 | 125篇 |
专业分类
系统科学 | 208篇 |
丛书文集 | 313篇 |
教育与普及 | 79篇 |
理论与方法论 | 144篇 |
现状及发展 | 11218篇 |
研究方法 | 1259篇 |
综合类 | 13459篇 |
自然研究 | 524篇 |
出版年
2013年 | 184篇 |
2012年 | 448篇 |
2011年 | 999篇 |
2010年 | 185篇 |
2009年 | 176篇 |
2008年 | 479篇 |
2007年 | 570篇 |
2006年 | 561篇 |
2005年 | 574篇 |
2004年 | 620篇 |
2003年 | 549篇 |
2002年 | 518篇 |
2001年 | 809篇 |
2000年 | 797篇 |
1999年 | 531篇 |
1992年 | 478篇 |
1991年 | 380篇 |
1990年 | 420篇 |
1989年 | 401篇 |
1988年 | 373篇 |
1987年 | 420篇 |
1986年 | 427篇 |
1985年 | 526篇 |
1984年 | 419篇 |
1983年 | 338篇 |
1982年 | 276篇 |
1981年 | 290篇 |
1980年 | 361篇 |
1979年 | 847篇 |
1978年 | 651篇 |
1977年 | 631篇 |
1976年 | 510篇 |
1975年 | 543篇 |
1974年 | 767篇 |
1973年 | 669篇 |
1972年 | 635篇 |
1971年 | 803篇 |
1970年 | 1092篇 |
1969年 | 773篇 |
1968年 | 664篇 |
1967年 | 769篇 |
1966年 | 705篇 |
1965年 | 489篇 |
1959年 | 261篇 |
1958年 | 454篇 |
1957年 | 305篇 |
1956年 | 295篇 |
1955年 | 232篇 |
1954年 | 218篇 |
1948年 | 234篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
F. M. Goñi J. M. Valpuesta M. C. Barbero E. Rial J. I. G. Gurtubay J. M. Macarulla 《Cellular and molecular life sciences : CMLS》1984,40(2):193-195
Summary The solubilizing effect of Triton X-100 on beef heart submitochondrial particles (ETPH) has been studied under various physiological conditions. Coupled, uncoupled and azide-inhibited ETPH particles have been studied. Quantitative and qualitative differences are found in the proteins solubilized by the detergent from ETPH particles under the various conditions tested.Acknowledgments: This work was supported in part by a grant from a Spanish Comisión Asesora para la Investigación Cientifica y Técnica. M.C. Barbero was recipient of a scholarship from the Basque Government. 相似文献
92.
K. Nielsen J. Sheppard W. Holmes I. Tizard 《Cellular and molecular life sciences : CMLS》1978,34(1):118-119
Summary Rats infected withTrypanosoma lewisi or decomplemented by injection of cobra venom factor or complement activating factor of trypanosomes were found to be more susceptible to infection withSalmonella typhimurium. Decomplemented rats subsequently infected withT. lewisi developed higher blood parasitemia than did normalT. lewisi infected rats.This project is supported by the National Research Council of Canada grant A 0068 and a grant from the International Development Research Center. 相似文献
93.
C. N. Powell 《Cellular and molecular life sciences : CMLS》1978,34(11):1450-1451
Summary 9 groups of 6 female rats were used in an experiment using fraction 3 ofTrypanosoma rhodesiense. 500 g gave 100% immunoprotection and 1000 and 1500 g gave 66% immunoprotection when challenged with 5×102
T. brucei. 2 groups of 10 female rats were tested for a short period inoculation immune response. In this, 750 g of fraction 3 ofT. rhodesiense gave 70% immunoprotection when challenged withT. brucei.I thank the University of Zambia for support; Dr M. A. Q. Awan, Mazabuka, Zambia, forT. rhodesiense andT. brucei; Prof. J. W. Kibukamusoke, Dr O. Okong'o and Dr W. W. Anokbonggo for advice; Mr L. Nyaliti for technical help. 相似文献
94.
Summary The vast majority of oil-droplets in the dark and light-adapted retinal twin-cones ofPoecilia reticulata is of the matrix-type. In bright light (day light+overhead strip light) there occurs in some regions a very pronounced numerical change from matrix to cristate-type, whereas other regions remain unaffected. The functional significance of these differences is discussed. 相似文献
95.
C Torrossian 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1978,286(9):693-696
The oxygen consumption of "hibernating" ants shows a grouping effect translated by a significant decrease in the level of oxygen consumption as a function of grouping effect. The general relation between oxygen consumption and the living body mass is the same, if the living material belongs to a single animal, or a social community of ants. 相似文献
96.
97.
The spontaneous conversion of mammalian cyclic GMP-dependent protein kinase (G-PK) into modulator-dependent protein kinase (type II) (M-PKII) in the absence of cGMP or histone was observed in vitro. The findings, together with similarity in substrate protein specificity, suggest that M-PKII is the catalytic subunit of mammalian G-PK. 相似文献
98.
Summary We analyzed inheritance of 5Es-1 alleles inP. leucopus and found them to be co-dominant and segregating from a single autosomal locus, thereby verifying assumptions of Mendelian inheritance imfield data. We also described an allele that is silent in hemolysate, but is active in liver extract.Acknowledgment. Laboratory analysis was partially supported by a grant-in-aid (No. 0171-02-240-76) to Kaufman from the Research Foundation of State University of New York. 相似文献
99.
J. Kędziora M. Soszyński G. Bartosz H. Witas W. Leyko 《Cellular and molecular life sciences : CMLS》1980,36(8):926-927
Summary A statistically significant decrease of prealbumin and statistically significant increases of alpha2-macroglobulin and IgA were found in blood plasma of patients with Down's syndrome using quantitative crossed immunoelectrophoresis.We are indebted to Prof. T.C. Bøg-Hansen, University of Copenhagen, for the helpful discussion of our results. 相似文献
100.
W. D. MacRae G. F. Q. Chan Chi-Kit Wat G. H. N. Towers J. Lam 《Cellular and molecular life sciences : CMLS》1980,36(9):1096-1097
Summary -Terthienyl and 5 polyacetylenes were examined for chromosome damaging activity using Syrian hamster cells. None of these naturally occurring compounds induced sister chromatid exchanges and neither -terthienyl nor phenylheptatriyne induced chromosome aberrations.The authors wish to thank the National Science and Engineering Research Council for financial support of this research. 相似文献