全文获取类型
收费全文 | 420016篇 |
免费 | 43758篇 |
国内免费 | 196篇 |
出版年
2016年 | 4521篇 |
2015年 | 5956篇 |
2014年 | 7058篇 |
2013年 | 10625篇 |
2012年 | 11484篇 |
2011年 | 11969篇 |
2010年 | 8151篇 |
2009年 | 7481篇 |
2008年 | 10692篇 |
2007年 | 11340篇 |
2006年 | 10682篇 |
2005年 | 10160篇 |
2004年 | 10257篇 |
2003年 | 10022篇 |
2002年 | 9825篇 |
2001年 | 17349篇 |
2000年 | 17394篇 |
1999年 | 14053篇 |
1998年 | 4977篇 |
1997年 | 5289篇 |
1996年 | 5011篇 |
1995年 | 4728篇 |
1994年 | 4633篇 |
1993年 | 4630篇 |
1992年 | 12271篇 |
1991年 | 12074篇 |
1990年 | 12085篇 |
1989年 | 11859篇 |
1988年 | 11166篇 |
1987年 | 10502篇 |
1986年 | 9821篇 |
1985年 | 10239篇 |
1984年 | 8439篇 |
1983年 | 7276篇 |
1982年 | 5613篇 |
1981年 | 5020篇 |
1980年 | 4695篇 |
1979年 | 8082篇 |
1978年 | 6301篇 |
1977年 | 5940篇 |
1976年 | 5672篇 |
1975年 | 6130篇 |
1974年 | 6698篇 |
1973年 | 6569篇 |
1972年 | 6122篇 |
1971年 | 5535篇 |
1970年 | 4769篇 |
1969年 | 4782篇 |
1968年 | 4453篇 |
1967年 | 3808篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
V K Khugaeva E D Klimenko P N Aleksandrov G F Leskova M I Reutov 《Biulleten' eksperimental'no? biologii i meditsiny》1985,100(7):15-19
Experiments were made on rabbit fed an atherogenic diet (0.5 g/kg cholesterol) singly for 15 and 24 h and repeatedly for 3, 9 and 30 days. At early stages of lipid metabolism distress the interrelationship was established between blood rheological disorders and microcirculatory abnormalities. The dependence of the initial reaction of some rheological characteristics on their initial level was marked. 相似文献
52.
53.
E A Bardakhch'ian Iu G Kirichenko 《Biulleten' eksperimental'no? biologii i meditsiny》1986,102(7):97-100
Electron microscopy of the adrenal medulla and cortex during the intermediate period of endotoxin shock has revealed severe destructive changes in parenchymal cells. These changes are the reason for synthetic, secretory and trophic disturbances of glandular functions. Ultrastructural lesions indicate that stress exposure exceeds the adaptive capacity of cells, the majority of which are exhausted and killed. 相似文献
54.
55.
Synthesis of prenylquinones in chloroplasts 总被引:3,自引:0,他引:3
56.
Growth of fathead minnow yolk sac larvae was characterized from changes in dry weight and total content and concentrations of RNA, DNA and protein in fish exposed to a sublethal level of HCN (58 micrograms/l) and in age matched controls. Cyanide toxicosis occurred within 24 hr of exposure as evidenced by significant reductions in protein and RNA content and RNA/DNA ratio of larvae. After 96 hr exposure to HCN, larvae exhibited the same growth rate and protein synthetic rate (RNA/DNA) as control fish. HCN toxicosis and recovery is rapid and at least partial tolerance to HCN develops within 96 hr of exposure in larval fathead minnows. 相似文献
57.
58.
Two color light scattering identifies physical differences between lymphocyte subpopulations 总被引:1,自引:0,他引:1
Forward angle light scattering of two different wavelengths by cells in a flow cytometer was used to investigate physical differences between lymphocytes of different lineage, functional subclass and developmental stage. Correlation of the ultraviolet (UV: 351 nm and 364 nm) and 488 nm light scattering signals produced by lymphoid cells demonstrated that the two signals were not equivalent and that they placed different emphasis on the physical parameters characterizing lymphocytes. Both small T and B lymphocytes from peripheral lymphoid tissues and mitogenically activated large T and B lymphocyte blasts were discriminated by both wavelengths. Differences between the Lyt-2 negative and Lyt-2 positive T lymphocyte subsets were also apparent. Two color light scattering could also discriminate between immature thymocytes and mature peripheral T cells and between small bone marrow cells and mature peripheral B cells. In bone marrow an increase in UV light scattering coincided with the appearance of cell surface immunoglobulin on small cells. These data establish that two color light scattering is a sensitive probe for distinguishing cells of apparently similar morphology and that it can be used to study the physical changes that occur during lymphoid cell differentiation. 相似文献
59.
60.
G. E. Tanyi 《Bulletin of mathematical biology》1982,44(4):501-535
The Thom gradient model of morphogenesis poses the followinga posteriori problem: “From the observed morphology of a given natural process (effect) determine the dynamics of the process (cause)”. In this paper we consider the classicala priori problem: “Given the cause (dynamics) determine the effect (resultant morphology)”.
We find that in biochemical processes the mechanisms for energy activation, energy-matter interaction and energy dissipation
determine the dynamics. Furthermore there exists basic energy mechanisms which drive the equilibrium states through the elementary
catastrophes of Thom. A comparison with current theories shows that our models describe open ecological food chains and their
dynamical systems generalize the equations of organisation posed by M. Eigen.
Work supported by a Research Associateship of the International Centre for Theoretical Physics, P.O.B. 586, Miramare, 34100
Trieste, Italy. 相似文献