全文获取类型
收费全文 | 863063篇 |
免费 | 95754篇 |
国内免费 | 498篇 |
专业分类
959315篇 |
出版年
2018年 | 8063篇 |
2016年 | 10848篇 |
2015年 | 14096篇 |
2014年 | 16835篇 |
2013年 | 23999篇 |
2012年 | 26763篇 |
2011年 | 27462篇 |
2010年 | 18699篇 |
2009年 | 17309篇 |
2008年 | 24547篇 |
2007年 | 25518篇 |
2006年 | 23822篇 |
2005年 | 22997篇 |
2004年 | 22724篇 |
2003年 | 21543篇 |
2002年 | 21046篇 |
2001年 | 39698篇 |
2000年 | 39664篇 |
1999年 | 31304篇 |
1998年 | 10650篇 |
1997年 | 11215篇 |
1996年 | 10443篇 |
1995年 | 9709篇 |
1994年 | 9362篇 |
1993年 | 9425篇 |
1992年 | 25465篇 |
1991年 | 24693篇 |
1990年 | 24067篇 |
1989年 | 23394篇 |
1988年 | 21741篇 |
1987年 | 20547篇 |
1986年 | 19240篇 |
1985年 | 18943篇 |
1984年 | 15665篇 |
1983年 | 13435篇 |
1982年 | 10168篇 |
1981年 | 9166篇 |
1980年 | 8755篇 |
1979年 | 14968篇 |
1978年 | 11637篇 |
1977年 | 10674篇 |
1976年 | 9973篇 |
1975年 | 10915篇 |
1974年 | 12040篇 |
1973年 | 11703篇 |
1972年 | 10820篇 |
1971年 | 9881篇 |
1970年 | 8591篇 |
1969年 | 8295篇 |
1968年 | 7919篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
181.
182.
183.
184.
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
185.
186.
187.
188.
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
189.
190.
E Giannazzo F Licata G Li Volsi G Mio F Santangelo M Scivoli 《Bollettino della Società italiana di biologia sperimentale》1992,68(11):677-683
A computer-assisted analysis of the spatial distribution of neurons having homogeneous characteristics is described in this paper. The camera lucida drawings of sections of a brain nucleus and the points representing the neurons labeled on the basis of a specific behavior of discharge rates were digitized on a personal computer Amiga 2000 or IBM compatible. Our software provided: a) the computerized, stereotaxically oriented reconstruction of the stored sections and of the plotted neurons; b) the identification within each section of the mass center (MC) of the units sharing a given behavior and of the area where the density of such neurons was maximal (MDA). The routine was tested on the spatial distribution of neuronal responses to serotonin in the lateral vestibular nucleus. 相似文献