全文获取类型
收费全文 | 622796篇 |
免费 | 60168篇 |
国内免费 | 1226篇 |
专业分类
684190篇 |
出版年
2018年 | 16254篇 |
2017年 | 14988篇 |
2016年 | 13922篇 |
2015年 | 9433篇 |
2014年 | 10877篇 |
2013年 | 15696篇 |
2012年 | 21122篇 |
2011年 | 29497篇 |
2010年 | 22957篇 |
2009年 | 18446篇 |
2008年 | 24373篇 |
2007年 | 26346篇 |
2006年 | 15091篇 |
2005年 | 14712篇 |
2004年 | 14996篇 |
2003年 | 14400篇 |
2002年 | 13699篇 |
2001年 | 28623篇 |
2000年 | 28395篇 |
1999年 | 22058篇 |
1998年 | 6791篇 |
1997年 | 7351篇 |
1996年 | 6781篇 |
1995年 | 6259篇 |
1994年 | 6028篇 |
1993年 | 6030篇 |
1992年 | 17098篇 |
1991年 | 16362篇 |
1990年 | 15743篇 |
1989年 | 15252篇 |
1988年 | 13968篇 |
1987年 | 12975篇 |
1986年 | 12069篇 |
1985年 | 11840篇 |
1984年 | 9707篇 |
1983年 | 8126篇 |
1982年 | 6042篇 |
1981年 | 5411篇 |
1980年 | 5147篇 |
1979年 | 8964篇 |
1978年 | 6845篇 |
1977年 | 6302篇 |
1976年 | 5672篇 |
1975年 | 6276篇 |
1974年 | 6782篇 |
1973年 | 6572篇 |
1972年 | 6226篇 |
1971年 | 5699篇 |
1970年 | 4695篇 |
1969年 | 4417篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
112.
A new gas-liquid chromatographic method was developed for the determination of diethylether in whole blood. Ether was quantitated by peak area ratio analysis with n-propanol as the internal standard using a flame ionization detector. Blood ether concentrations were determined in cats undergoing inhalational anesthesia by ether in oxygen. In normal spontaneously breathing cats, anesthesia began at ether concentrations of about 0.6 g/l, and respiratory arrest occurred at 2.4 g/l and above. Mean arterial blood pressure was well maintained throughout the entire anesthetic range. In spinal artificially respired animals, mean arterial blood pressure correlated inversely with blood ether concentration. The data suggest that decline in blood pressure may be a useful sign of ether toxicity in spinal cats. 相似文献
113.
114.
115.
From three Fouquieria sp. 12 iridoid glucosides were isolated and identified. Eight of these were structurally related to galioside (monotropein methylester), while four were hydroxy substitution products of deoxyloganin. In three cases the glucoside occurred together with the corresponding 10-O-acetate. 相似文献
116.
S D Fordham 《Plastic and reconstructive surgery》1992,90(5):915-917
An indwelling nasal suction tampon is described that effectively controls both intraoperative and postoperative nasal hemorrhage. The significant benefits of this device are better intraoperative control for the surgeon and less complicated postoperative recovery. I do not have any financial involvement in this device, but I would like other nasal surgeons to benefit from its particular advantages. The device is available under the trade name Instant and may be obtained from Innovations by Westmed, 3351 E. Hemisphere Loop, Tucson, Ariz. 85706; (602) 294-7987. 相似文献
117.
C S Nicoll 《The Physiologist》1991,34(6):303, 306-308, 315
118.
119.
120.
Convenient extraction and radioimmunoassay methods for measurement of leukotrienes C4 and D4 (LTC4 and LTD4) in biological fluids are described. LTC4 or LTD4 in plasma was extracted with acetonitrile, and the extract was washed with dichloromethane then adjusted to pH 3.5 or 6.0, respectively. Each leukotriene was partially purified by using a C18-bonded silica cartridge and quantitated by radioimmunoassay. Amounts of LTC4 and LTD4 in the range of 0.025-1.6 ng could be assayed in plasma. This procedure was employed to examine the increase in plasma LTC4 (0.249 +/- 0.036 ng/ml) and LTD4 (1.399 +/- 0.235 ng/ml) of guinea pigs during intravenous challenge-induced anaphylactic bronchoconstriction, and the suppression of the increase of bronchoconstriction and leukotrienes by the administration of 5-lipoxygenase inhibitors such as E6080 (6-hydroxy-2-(4-sulfamoylbenzyl-amino)- 4,5,7-trimethylbenzothiazole hydrochloride), AA861 (2,3,5-trimethyl-6-(12-hydroxy-5,10-dodecadiynyl)-1,4-benzoquinone ) and phenidone. On the other hand, LTC4 and LTD4 were not detected in plasma after an inhaled challenge, though significant bronchoconstriction was provoked. It was concluded that the present study validates a new technique for quantitating plasma leukotrienes on the basis of pH and a suitable method for evaluating the pharmacological efficacy of 5-lipoxygenase inhibitors. 相似文献