全文获取类型
收费全文 | 9839篇 |
免费 | 31篇 |
国内免费 | 47篇 |
专业分类
系统科学 | 42篇 |
丛书文集 | 72篇 |
教育与普及 | 8篇 |
理论与方法论 | 21篇 |
现状及发展 | 4613篇 |
研究方法 | 479篇 |
综合类 | 4587篇 |
自然研究 | 95篇 |
出版年
2013年 | 73篇 |
2012年 | 164篇 |
2011年 | 247篇 |
2010年 | 51篇 |
2008年 | 183篇 |
2007年 | 223篇 |
2006年 | 199篇 |
2005年 | 189篇 |
2004年 | 218篇 |
2003年 | 162篇 |
2002年 | 187篇 |
2001年 | 312篇 |
2000年 | 302篇 |
1999年 | 205篇 |
1992年 | 191篇 |
1991年 | 134篇 |
1990年 | 137篇 |
1989年 | 119篇 |
1988年 | 116篇 |
1987年 | 137篇 |
1986年 | 124篇 |
1985年 | 210篇 |
1984年 | 159篇 |
1983年 | 138篇 |
1982年 | 117篇 |
1981年 | 111篇 |
1980年 | 130篇 |
1979年 | 295篇 |
1978年 | 259篇 |
1977年 | 232篇 |
1976年 | 230篇 |
1975年 | 254篇 |
1974年 | 281篇 |
1973年 | 222篇 |
1972年 | 212篇 |
1971年 | 280篇 |
1970年 | 402篇 |
1969年 | 278篇 |
1968年 | 279篇 |
1967年 | 275篇 |
1966年 | 248篇 |
1965年 | 175篇 |
1964年 | 85篇 |
1959年 | 105篇 |
1958年 | 149篇 |
1957年 | 125篇 |
1956年 | 90篇 |
1955年 | 80篇 |
1954年 | 99篇 |
1948年 | 66篇 |
排序方式: 共有9917条查询结果,搜索用时 31 毫秒
81.
V. Lattanzio V. V. Bianco D. Lafiandra 《Cellular and molecular life sciences : CMLS》1982,38(7):789-790
Summary A HPLC assay for L-Dopa, convicine, and vicine in broad-bean extracts has been developed. The distribution of these compounds in the different organs of the plant has been studied, especially in the seeds, where their presence may cause favism if the beans are used as food.Work supported by C.N.R. through Progetto Finalizzato Miglioramento delle produzioni vegetali per fini alimentari ed industriali mediante interventi genetici. Sottogrogetto leguminose da granella. Paper No. 200. 相似文献
82.
Effects were examined of atropine, diazepam, pethidene, promethazine, scopolamine, omnopon and papaverine on basal and noradrenaline-stimulated lipolysis in rat isolated fat cells and on rat adipose tissue cyclic AMP phosphodiesterase activity. Papaverine at high concentration (1 mM) inhibited both basal and hormone-stimulated lipolysis, whereas diazepam enhanced basal lipolysis. At a 'clinical dose', omnopon increased both basal and noradrenaline-stimulated lipolysis. Adipose tissue cAMP phosphodiesterase activity was strongly inhibited by 1 mM diazepam, papaverine, promethazine and omnopon (280 microgram ml-1). Lack of enhancement of lipolysis by the established cAMP phosphodiesterase antagonist papaverine, is compatible with simultaneous inhibition also of adipose adenyl cyclase. Diazepam-stimulated lipolysis is compatible with its phosphodiesterase inhibitory activity. It is proposed that papaverine-containing omnopon may offer some survival advantages during surgical stress by facilitating a caloric supply. 相似文献
83.
84.
85.
K. Mašek M. Zaoral J. Ježek V. Krchňák 《Cellular and molecular life sciences : CMLS》1979,35(10):1397-1398
Summary The immunoadjuvant activity of muramyl dipeptide seems to be critically dependent on the type of substitution of the -carboxyl group of the D-isoglutamine residue. Moreover the nonapeptide L-Ala-D-isoGlu-L-Lys-D-Ala-(Gly)5-OME also shows a definite effect. 相似文献
86.
Zusammenfassung Verabreichung von Isoprotenerol, eines -adrenergen Agonisten, induziert einen signifikant höheren Anstieg der Aktivität der Serotonin-N-Acetyltransferase in der Epiphyse von spontan hypertensiven, im Vergleich mit normotensiven, Rattenmännchen. Derselbe Unterschied wurde auch bei Weibchen beobachtet, jedoch liegen die Aktivitätswerte bei spontan hypertensiven Männchen allgemein höher. Die durch Isoprotenerol erhöhte Induktion der Serotonin-N-Acetyltransferase erzeugt hinsichtlich der Catecholamine in den Pinealozyten von spontan hypertensiven Ratten eine veränderte Reaktivität der Achse -Rezeptor-Adenylzyklasesystem-Serotonin-N-Acetyl transferase. 相似文献
87.
P. Pani A. Sanna M. I. Brigaglia A. Columbano L. Congiu 《Cellular and molecular life sciences : CMLS》1976,32(11):1449-1451
Summary Acute toxicity induced by DMN was partially prevented by previously administering methyl mercuric chloride (MMC), a chemical inhibitor of the drug metabolizing enzyme system (DMES). We have studied the early changes occurring during the course of DMN-intoxication, namely disaggregation of polysomal profiles and necrosis, evaluated morphologically and by the release of S-GPT.This work was supported by Consiglio Nazionale delle Ricerche, Roma, Italy. 相似文献
88.
Summary The serum activities of aspartate aminotransferase, alanine aminotransferase, -hydroxybutyrate dehydrogenase and creatine phosphokinase have been measured in the African elephant. In general, the values were broadly comparable with those of man except that alanine aminotransferase was much lower and creatine phosphokinase higher. No variation due to age, sex, season or location was observed. 相似文献
89.
We examined effects of several vasoactive peptides (substance P, physalaemin, neurotensin, bradykinin, angiotensin etc.) on the excitability of molluscan giant neurones identified in the subesophageal ganglia of Achatina fulica Férussac. Of these peptides, only physalaemin showed a remarkable excitatory effect on a giant tonically autoactive neurone. 相似文献
90.
V. R. Osório E Castro M. G. P. Vale A. P. Carvalho 《Cellular and molecular life sciences : CMLS》1976,32(4):424-426
Summary The effect of the antibiotic X-537A on the phosphorylated ATPase (EP) was investigated. The results show that X-537A depresses the level of EP which is dependent on the Ca2+ gradient, while the Ca2+-independent EP is not affected.
Acknowledgments. This work was supported by grants from the Instituto de Alta Cultura of the Portuguese Ministry of Education (No. CB/2) and the Calouste Gulbenkian Foundation. 相似文献