全文获取类型
收费全文 | 360880篇 |
免费 | 28026篇 |
国内免费 | 97篇 |
专业分类
389003篇 |
出版年
2018年 | 4189篇 |
2017年 | 4038篇 |
2016年 | 5100篇 |
2015年 | 4962篇 |
2014年 | 6614篇 |
2013年 | 9480篇 |
2012年 | 11072篇 |
2011年 | 11924篇 |
2010年 | 8306篇 |
2009年 | 7319篇 |
2008年 | 10608篇 |
2007年 | 11093篇 |
2006年 | 10588篇 |
2005年 | 9888篇 |
2004年 | 10111篇 |
2003年 | 9734篇 |
2002年 | 9710篇 |
2001年 | 15832篇 |
2000年 | 15708篇 |
1999年 | 12024篇 |
1998年 | 3819篇 |
1997年 | 3774篇 |
1996年 | 3427篇 |
1995年 | 3164篇 |
1992年 | 9536篇 |
1991年 | 9729篇 |
1990年 | 9488篇 |
1989年 | 9496篇 |
1988年 | 8757篇 |
1987年 | 8248篇 |
1986年 | 7531篇 |
1985年 | 7853篇 |
1984年 | 6333篇 |
1983年 | 5319篇 |
1982年 | 3615篇 |
1981年 | 3180篇 |
1980年 | 3132篇 |
1979年 | 5963篇 |
1978年 | 4647篇 |
1977年 | 4232篇 |
1976年 | 3995篇 |
1975年 | 4808篇 |
1974年 | 5315篇 |
1973年 | 5274篇 |
1972年 | 4791篇 |
1971年 | 4485篇 |
1970年 | 3897篇 |
1969年 | 3795篇 |
1968年 | 3557篇 |
1967年 | 3203篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
The flight muscle preparations of the dragonfly Pantala flavescens and the aquatic beetle Cybister confusus showed extremely low levels of lactic dehydrogenase activity and high levels of alpha-glycerophosphate dehydrogenase (insoluble) activity. The activities of these two enzymes in the leg muscle of the beetle were approximately the same (1:1), but lactic dehydrogenase activity was several times higher than that in the flight muscles of both Insects. These results have been interpreted as indicating the high energy-yielding demands of the flight muscles during continuous sustained activity, while the leg muscles of the beetle which are involved in swimming activity derive their energy predominantly through anaerobic glycolysis. 相似文献
992.
993.
In view of the importance of impedance plethysmography requirements are formulated for a modern impedance measuring device basing on a long experience with this method of measurement. The principle mode of action of the measuring equipment and the pneumatics with the timing element are described. A number of recordings is shown to illustrate the universality of the measuring equipment. 相似文献
994.
The gastric mucous membrane was studied in the hibernating animal Citellus erythrogenys in different seasons (during 7-8 months a year the animal is in hibernation and its digestive tract is not functioning). During hibernation the general amount of enterochromaffin-like cells decreases and their composition changes: the number of active cells diminishes and that of less active cells grows. Such dynamics of cells suggests the participation of enterochromaffin-like cells of Citellus erythrogenys in the regulation of gastric secretion (in rats and mice these cells contain histamine stimulating the mucous membrane glands). The amount of true enterochromaffin cells is not sufficiently changed and they seem to be not directly related with digestion but to be producers of serotonin which (together with serotonin of the brain) takes part in sustaining the mechanisms of appearance and supporting of winter hibernation. 相似文献
995.
996.
997.
M Kubel B Freistedt P Hammer V Thierbach W Helbig B Haustein W Schultze 《Folia haematologica (Leipzig, Germany : 1928)》1982,109(2):355-364
Thrombocyte substitution is an essential prerequisite for intensive cytoreductive therapy in acute leukemia. Evaluating 228 thrombocyte transfusions in 17 patients shows that the clinical effectiveness of thrombocyte concentrates can be increased by making the coordination of HLA antigens of donor and receiver as good as possible. When measured in the corrected increment (CI) 24 hours after transfusion, the effectiveness of A3/B1 match preparations (CI = 7.0 +/- 1.6) is significantly higher than that of random preparations (CI = 3.0 +/- 0.5). With the presence of HLA antibodies an effective substitution (CI24 greater than or equal to 4.5) can only be achieved by A3/B1 match thrombocytes. This can only be realized by applying the fourfold thrombapheresis of single donors. 相似文献
998.
Daphniopsis australis, a new species of cladoceran in Australian salt lakes, is described, and some brief comments on its distribution are given. 相似文献
999.
L M Iarovaia E A Shmeleva V S Samsonova E V Kulikovskaia 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1985,(8):26-30
The chemical characteristics of 6 batches of the preparation, obtained from the cell wall of C. diphtheriae grown in liquid and solid culture media, with respect to their content of nitrogen, hexoses, pentoses, total amino sugars, lipids and to the possible admixture of nucleic acids are presented. From the results of the chemical analysis of these batches their standardization according to the ratio of total amino sugars and pentoses to total nitrogen in C. diphtheriae cell-wall preparation is proposed. 相似文献
1000.
I. Ya. Kleinbok 《Neurophysiology》1986,18(6):542-547
The effect of picrotoxin (at sub-convulsant doses, i.v.) on the background and invoked spike activity of cat dorsal horn internerons was investigated while thermal and mechanical influences were at work on the skin receptor areas. It was found that information on skin temperature is modulated at the presynaptic level and largely mediated by competitive interaction between large and small diameter fibers.Institute of Physiology, Academy of Sciences of the Kazakh SSR, Alma Ata. Translated from Neirofiziologiya, Vol. 18, No. 6, pp. 773–779, November–December, 1986. 相似文献