全文获取类型
收费全文 | 881篇 |
免费 | 14篇 |
国内免费 | 3篇 |
专业分类
系统科学 | 17篇 |
理论与方法论 | 28篇 |
现状及发展 | 485篇 |
研究方法 | 72篇 |
综合类 | 264篇 |
自然研究 | 32篇 |
出版年
2018年 | 19篇 |
2017年 | 15篇 |
2016年 | 17篇 |
2015年 | 13篇 |
2014年 | 25篇 |
2013年 | 17篇 |
2012年 | 37篇 |
2011年 | 70篇 |
2010年 | 21篇 |
2009年 | 8篇 |
2008年 | 34篇 |
2007年 | 24篇 |
2006年 | 36篇 |
2005年 | 41篇 |
2004年 | 21篇 |
2003年 | 27篇 |
2002年 | 29篇 |
2001年 | 18篇 |
2000年 | 11篇 |
1999年 | 11篇 |
1998年 | 9篇 |
1993年 | 5篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1981年 | 16篇 |
1980年 | 9篇 |
1979年 | 23篇 |
1978年 | 22篇 |
1977年 | 11篇 |
1976年 | 20篇 |
1975年 | 11篇 |
1974年 | 10篇 |
1973年 | 16篇 |
1972年 | 8篇 |
1971年 | 21篇 |
1970年 | 13篇 |
1969年 | 15篇 |
1968年 | 20篇 |
1967年 | 15篇 |
1966年 | 9篇 |
1965年 | 18篇 |
1964年 | 7篇 |
1954年 | 5篇 |
1948年 | 6篇 |
1947年 | 6篇 |
排序方式: 共有898条查询结果,搜索用时 15 毫秒
811.
A. Sciocia-Santoro D. Cavallini Anna M. Degener R. Perez-Bercoff G. Rita 《Cellular and molecular life sciences : CMLS》1977,33(4):451-453
Summary L-amino-ethyl-cysteine clearly inhibits replication of Mengovirus; another RNA-virus (vesicular stomatitis virus) is completely insensitive. Protein synthesis is not impaired, but no active viral RNA-polymerase is detected.This work was partly supported by grant No. 73.01407.44 115.0107 of Consiglio Nazionale delle Ricerche, Roma, Italy. The technical collaboration of P. Meo and G. Conciatori is gratefully acknowledged. 相似文献
812.
813.
In this paper the underlying systemic unity of the research reported in the two previous articles is sought. The research journey is examined in order to draw lessons concerning our systemic practice. In addition, an effort is made to relate Interpretive Systemology to some strands of systems, management and action research sciences. In so doing, we expect to draw some links that could be established between interpretive systemologists and the community of researchers who compose the select audience of SPAR. 相似文献
814.
The gene encoding ATP-binding cassette transporter 1 is mutated in Tangier disease. 总被引:26,自引:0,他引:26
M Bodzioch E Orsó J Klucken T Langmann A B?ttcher W Diederich W Drobnik S Barlage C Büchler M Porsch-Ozcürümez W E Kaminski H W Hahmann K Oette G Rothe C Aslanidis K J Lackner G Schmitz 《Nature genetics》1999,22(4):347-351
Tangier disease (TD) is an autosomal recessive disorder of lipid metabolism. It is characterized by absence of plasma high-density lipoprotein (HDL) and deposition of cholesteryl esters in the reticulo-endothelial system with splenomegaly and enlargement of tonsils and lymph nodes. Although low HDL cholesterol is associated with an increased risk for coronary artery disease, this condition is not consistently found in TD pedigrees. Metabolic studies in TD patients have revealed a rapid catabolism of HDL and its precursors. In contrast to normal mononuclear phagocytes (MNP), MNP from TD individuals degrade internalized HDL in unusual lysosomes, indicating a defect in cellular lipid metabolism. HDL-mediated cholesterol efflux and intracellular lipid trafficking and turnover are abnormal in TD fibroblasts, which have a reduced in vitro growth rate. The TD locus has been mapped to chromosome 9q31. Here we present evidence that TD is caused by mutations in ABC1, encoding a member of the ATP-binding cassette (ABC) transporter family, located on chromosome 9q22-31. We have analysed five kindreds with TD and identified seven different mutations, including three that are expected to impair the function of the gene product. The identification of ABC1 as the TD locus has implications for the understanding of cellular HDL metabolism and reverse cholesterol transport, and its association with premature cardiovascular disease. 相似文献
815.
J. C. G. Milicua A. Barandiarán J. M. Macarulla A. M. Gárate R. Gómez 《Cellular and molecular life sciences : CMLS》1985,41(11):1485-1486
Summary A blue carotenoprotein from the crayfishProcambarus clarkii was extracted and purified. This carotenoprotein contains the carotenoid astaxanthin as a prosthetic group. In the present work we have identified by reconstitution, after removing the native carotenoid, some characteristics of the carotenoids that could bind to the apoprotein. The carotenoid must have two oxo groups at positions 4, 4 and two hydroxyl groups at positions 3, 3 the hexagonal or pentagonal end structure being indifferent. It has been proved that changes in the polyene chain structure such as triple bonds destroy this binding capacity. 相似文献
816.
B. Matkovics L. Lakatos L. Szabó L. Karmazsin 《Cellular and molecular life sciences : CMLS》1981,37(1):79-80
Summary In the liver of neonate rats and in tissues of adult rats a study was made of the effect of D-penicillamine treatment in vivo on the enzymes of peroxide metabolism, lipid peroxidation and other components. It was found that D-penicillamine primarily acts by decreasing lipid peroxidation, thus stabilizing the membrane.Properties of enzymes. Serial publication Part XVI.Acknowledgment. We should like to take the opportunity to express our thanks to the Directorate of Knoll AG, Ludwigshafen. FRG, for the kind gift of Metalcaptase®. 相似文献
817.
J. Steinsapir S. León P. Bustón M. Alburquerque A. M. Rojas A. Fernández R. Pacheco A. Tchernitchin 《Cellular and molecular life sciences : CMLS》1979,35(11):1472-1474
Summary Theophylline increases and triodothyronine decreases uterine edema induced by physiological doses of estradiol-17. Both of them decrease estrogen-induced uterine eosinophilia and the number of blood eosinophils, suggesting an explanation for the results in the uterus.Acknowledgments.—We wish to thank Dr G. Pineda, Salvador Hospital, Santiago, for the gift of L-triiodothyronine (Sigma). This work was supported by grant B 012-783, Servicio de Desarrollo Científico y Creación Artística, University of Chile. 相似文献
818.
Rita Pascolini Anna Maria Gargiulo A. Spreca A. Orlacchio 《Cellular and molecular life sciences : CMLS》1979,35(10):1315-1317
Summary The localization of adenylate-cyclase activity inDugesia lugubris s.l. has been investigated cytochemically using 5-adenylyl-imidodiphosphate as substrate. The enzyme was localized in mucous gland cells, in rhabdite cells, in intercellular spaces and also in nerve endings of this planarian. The presence of adenylate-cyclase on the membrane suggests that it might mediate different stimulus-secretion coupling by increasing cyclic AMP synthesis in specialized areas of the planarian.Supported in part by a grant from Consiglio Nazionale delle Ricerche, Rome.Acknowledgments. This work was performed with the technical assistence of the laboratory of Electron Microscopy of the University of Perugia. 相似文献
819.
Krzysztof Wójtowicz 《Foundations of Science》1998,3(2):207-229
In this article the problem of unification of mathematical theories is discussed. We argue, that specific problems arise here, which are quite different than the problems in the case of empirical sciences. In particular, the notion of unification depends on the philosophical standpoint. We give an analysis of the notion of unification from the point of view of formalism, Gödel's platonism and Quine's realism. In particular we show, that the concept of “having the same object of study” should be made precise in the case of mathematical theories. In the appendix we give a working proposal of a certain understanding of this notion. 相似文献
820.
Ramsés Fuenmayor Mario Bonucci Hernán López-Garay 《Systemic Practice and Action Research》1991,4(5):507-525
This article is a summary of an interpretive-systemic study of the University of Los Andes in Venezuela. Following the methodological guidelines of interpretive systemology, three interpretive contextual systems were designed in order to comprehend the sense of the university. These three interpretive contexts were derived from possible different interpretations of the University Law (Statutes). Results obtained from the thematic interpretation of university activities and decision taking reveal an institution removed from any of the missions depicted in the interpretive contexts. A fourth interpretive context was designed to provide an interpretation of the regulative role the institution plays in order to maintain a particular social order and power structure. This fourth interpretive context shows greater interpretive power with regard to actual university activities than the other three. 相似文献