全文获取类型
收费全文 | 781803篇 |
免费 | 95050篇 |
国内免费 | 432篇 |
专业分类
877285篇 |
出版年
2016年 | 8511篇 |
2015年 | 12961篇 |
2014年 | 14928篇 |
2013年 | 20789篇 |
2012年 | 23742篇 |
2011年 | 23704篇 |
2010年 | 16066篇 |
2009年 | 15281篇 |
2008年 | 21745篇 |
2007年 | 22358篇 |
2006年 | 20905篇 |
2005年 | 20157篇 |
2004年 | 19970篇 |
2003年 | 19324篇 |
2002年 | 18743篇 |
2001年 | 34302篇 |
2000年 | 34738篇 |
1999年 | 28008篇 |
1998年 | 10738篇 |
1997年 | 11383篇 |
1996年 | 10925篇 |
1995年 | 10344篇 |
1994年 | 10190篇 |
1993年 | 10016篇 |
1992年 | 23589篇 |
1991年 | 22851篇 |
1990年 | 22491篇 |
1989年 | 21814篇 |
1988年 | 20087篇 |
1987年 | 19748篇 |
1986年 | 18120篇 |
1985年 | 18193篇 |
1984年 | 15121篇 |
1983年 | 13205篇 |
1982年 | 10552篇 |
1981年 | 9399篇 |
1980年 | 8959篇 |
1979年 | 14552篇 |
1978年 | 11703篇 |
1977年 | 10567篇 |
1976年 | 9967篇 |
1975年 | 10805篇 |
1974年 | 11629篇 |
1973年 | 11419篇 |
1972年 | 10230篇 |
1971年 | 9493篇 |
1970年 | 8111篇 |
1969年 | 7666篇 |
1968年 | 6846篇 |
1967年 | 6174篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
211.
Y Wattanagoon R E Phillips D A Warrell K Silamut S Looareesuwan B Nagachinta D J Back 《BMJ (Clinical research ed.)》1986,293(6538):11-13
In a study of intramuscular injection of quinine eight adults with moderately severe falciparum malaria resistant to chloroquine were treated with quinine dihydrochloride, being given a loading dose of 20 mg salt (16.7 mg base)/kg followed by three or four eight hourly maintenance doses of 10 mg salt (8.3 mg base)/kg injected into the anterior thigh. All patients responded to treatment. Fever and parasite clearance times (mean (SD) 60 (23) h and 53 (22) h respectively) were comparable with those obtained with intravenous quinine. The mean peak plasma quinine concentration of 11.0 mg/l (34.4 mu mol/l) [corrected] was reached a median of five hours after administration of the loading dose. In all patients plasma quinine concentrations exceeded the high minimum inhibitory concentration for Plasmodium falciparum malaria prevalent in Thailand within four hours of the start of treatment but did not cause toxicity other than mild cinchonism. When intravenous infusion is not possible an intramuscular quinine loading dose is an effective means of starting treatment in patients with moderately severe falciparum malaria who cannot swallow tablets. 相似文献
212.
In this paper the recent population changes of the Wild Boar in different European countries is analysed through the study of hunting statistics. A simultaneous increase in numbers is observed throughout the whole area during the period 1965–1975. From 1975 onwards the population stabilizes itself apart from in peripheral areas like Finland. Potentially favourable factors which play a part in this process are discussed and certain reproductive and dispersive characteristics which favour its invasive behaviour are discussed. 相似文献
213.
214.
215.
We studied recipient mating ability in the presence of excess F'lac donors. Ninety-five percent of recipients were able to receive F'lac in 30-min matings. Competition between an F'-lac donor and an F'lac traI donor, which mobilized a ColE1 derivative (pML2), showed that each recipient mated with an average of two to three donors in 30 min. Experiments in which the competing donor was added at different times showed that some competition occurred throughout the 30-min mating period, which suggested that aggregate formation was spread over this time. 相似文献
216.
217.
"Pertussis toxin induces tachycardia and impairs the increase in blood pressure produced by alpha 2-adrenergic agonists" 总被引:4,自引:0,他引:4
Administration of purified pertussis toxin to rats induced persistent tachycardia, (observed in conscious rats but not after pithing); as little as 0.05 microgram/100 g produced a significant effect. Pertussis toxin-treatment did not affected the pressor response produced in the pithed rats by the alpha 2-adrenergic agonist methoxamine but markedly diminished the pressor effect of the alpha 2-adrenergic agonists clonidine and azepexole. A role of adenylate cyclase inhibition in the action of postsynaptic vascular alpha 2-adrenergic receptors is suggested. 相似文献
218.
219.
M T Chauvet T Colne D Hurpet J Chauvet R Acher 《Biochemical and biophysical research communications》1983,116(1):258-263
Mesotocin ([Ile8]-oxytocin), lysipressin ([ Lys8]-vasopressin) and phenypressin ([Phe8]-vasopressin) have been identified in the western gray kangaroo (Macropus fuliginosus) as well as four other macropodids. Lysipressin and phenypressin, which differ by the amino acids in positions 2 (Tyr/Phe) and 8 (Lys/Arg) are likely products of two separate vasopressin-like genes. It is assumed that arginine vasopressin found in most mammals is the product of two identical genes which can be revealed in some species by differential mutations as seen usually in marsupials. The duality can also be revealed by differential mutations in another domain of the precursors, such as the neurophysin (MSEL-neurophysin), as observed in the ox. 相似文献
220.
Leucostasis, an underestimated cause of death in leukaemia 总被引:1,自引:0,他引:1
Massive sludging of leukaemic cells in blood vessels is a frequent and often lethal complication of leukaemia. In a retrospective clinicopathological study on the causes of death in 52 patients with acute myeloid leukaemia and myeloproliferative disease, pulmonary leucostasis was found in 40% of the patients. In many of these patients the vessels of the heart, brain and testes were also involved. In search for signs and symptoms specific for leucostasis, the clinical records of the 21 patients with leucostasis (the study group) were compared to those of 20 patients without leucostasis (the control group). Dysfunction of the organs most affected by leucostasis, namely lungs, heart and brain, was found more often in the study group than in the controls, but the combination of unexplained fever with cardiopulmonary and/or central nervous system failure occurred almost exclusively and in half of the patients with leucostasis. Leucostasis occurs predominantly, but not exclusively, in patients with high leucocyte counts, and especially, but again not exclusively, when the leucocyte counts rise sharply. 相似文献