全文获取类型
收费全文 | 2277篇 |
免费 | 20篇 |
国内免费 | 2篇 |
专业分类
系统科学 | 69篇 |
丛书文集 | 1篇 |
教育与普及 | 1篇 |
理论与方法论 | 27篇 |
现状及发展 | 1440篇 |
研究方法 | 122篇 |
综合类 | 562篇 |
自然研究 | 77篇 |
出版年
2020年 | 21篇 |
2018年 | 38篇 |
2017年 | 34篇 |
2016年 | 42篇 |
2015年 | 37篇 |
2014年 | 23篇 |
2013年 | 33篇 |
2012年 | 75篇 |
2011年 | 120篇 |
2010年 | 36篇 |
2009年 | 19篇 |
2008年 | 66篇 |
2007年 | 50篇 |
2006年 | 73篇 |
2005年 | 72篇 |
2004年 | 60篇 |
2003年 | 61篇 |
2002年 | 58篇 |
2001年 | 43篇 |
2000年 | 21篇 |
1999年 | 25篇 |
1992年 | 24篇 |
1991年 | 19篇 |
1986年 | 17篇 |
1985年 | 15篇 |
1984年 | 30篇 |
1983年 | 18篇 |
1982年 | 18篇 |
1981年 | 22篇 |
1980年 | 18篇 |
1979年 | 44篇 |
1978年 | 38篇 |
1977年 | 51篇 |
1976年 | 39篇 |
1975年 | 31篇 |
1974年 | 42篇 |
1973年 | 53篇 |
1972年 | 48篇 |
1971年 | 45篇 |
1970年 | 74篇 |
1969年 | 64篇 |
1968年 | 94篇 |
1967年 | 68篇 |
1966年 | 57篇 |
1965年 | 50篇 |
1964年 | 45篇 |
1963年 | 22篇 |
1962年 | 24篇 |
1961年 | 17篇 |
1959年 | 15篇 |
排序方式: 共有2299条查询结果,搜索用时 15 毫秒
991.
Resumen Se describen en la masa ganglionar ventral del moluscoCryptomphallus aspersa (Gasteropoda, Pulmonata) la presencia de varios tipos de neuronas bipolares entremezcladas con las típicas unipolares. Estas observaciones morfológicas se discuten en relación a los hallazgos obtenidos previamente con técnicas electrofisiológicas por otros autores. 相似文献
992.
993.
Renée A. Corral O. O. Orazi María E. González 《Cellular and molecular life sciences : CMLS》1976,32(3):284-285
Summary The guanidine function can be detected and its substitution pattern determined taking into account the1H-NMR signals of the N–H and N–C–H groups. Satisfactory results were obtained with mono-to penta-substituted guanidines (as picrate salts).Part XX ofStudies on Plants; preceding part,R. A. Corral, O. O. Orazi andI. A. Benages, Tetrahedron29, 205 (1973). 相似文献
994.
In this introductory paper to the special issue ofSystems Practice devoted to Interpretive Systemology, some of the conditions under which this trend in systems thinking has come to life are briefly depicted. For that purpose a wider and a narrower scene are presented. The wider scene presents the general questions and problems that are to be tackled by Interpretive Systemology, within a wide international perspective of systems thinking and practice. The narrower scene, which is related to more particular conditions, shows how some circumstances connected to the socalled Third World or underdeveloped countries have helped to trigger the launching of Interpretive Systemology. Finally, a brief outline of the research program for Interpretive Systemology is introduced. 相似文献
995.
Phagocytosis of native allogenic red blood cells was observed in cultures of skin fibroblasts obtained from patients with neuronal ceroid-lipofuscinosis, Niemann-Pick disease type C and morbus Fabry. Occasional phagocytizing cells were observed in 9 other syndromes. Cells from three normal donors did not phagocytize. 相似文献
996.
Summary Pineal N-acetyltransferase activity in the male Syrian hamster exhibited a daily rhythm; the maximal night-time value was 3.5-fold higher than the day-time value. When hamsters were exposed to light at night N-acetyltransferase declined within 30 min to 1/5 of its former activity. These results indicate that in the Syrian hamster the pineal melatonin rhythm may be regulated at least partly via changes in N-acetyltransferase activity.The authors are grateful to Mrs Marie Svobodová for her skillful technical assistance. 相似文献
997.
M. Pospíšil J. Jary Jaromíra Netíková M. Marek 《Cellular and molecular life sciences : CMLS》1982,38(10):1232-1234
Summary A single pre- or postirradiation application of -(13)-D-glucan, a potent reticuloendothelial stimulant, enhances hemopoietic recovery in sublethally gamma-irradiated mice. Pretreatment of mice with glucan significantly reduces lethal radiation effects. 相似文献
998.
Summary The dynamic and static phases of the thermogenic response to i.v. infused noradrenaline (NA) do not reflect the arterial concentration of NA; according to the equation presented here they are a function of the influx rate. 相似文献
999.
Summary An apparent suppression of dot-like exchanges in C-bands and late replicating DNA-rich regions of chromosomes has been observed inAllium cepa. This result suggests that the occurrence of SCE very near each other could be avoided in these chromosomal regions. 相似文献
1000.
V. Wagner M. Wagnerová J. Kříž D. Wokounová B. Šlesingerová 《Cellular and molecular life sciences : CMLS》1976,32(11):1369-1371
Summary In a group of 84 pairs of 11-year-old children of both sexes, the level of the
1-antitrypsin (
1-AT) were ascertained in the autumn and spring. Although the mean levels of
1-AT in the two seasons hardly differed, the highly significant seasonal changes in the distribution curves of
1-AT values were noted in boys, whereas the levels showed higher stability in girls. 相似文献