全文获取类型
收费全文 | 2424篇 |
免费 | 262篇 |
国内免费 | 1篇 |
出版年
2021年 | 29篇 |
2020年 | 21篇 |
2019年 | 22篇 |
2018年 | 26篇 |
2017年 | 40篇 |
2016年 | 61篇 |
2015年 | 83篇 |
2014年 | 83篇 |
2013年 | 136篇 |
2012年 | 190篇 |
2011年 | 154篇 |
2010年 | 96篇 |
2009年 | 78篇 |
2008年 | 144篇 |
2007年 | 135篇 |
2006年 | 131篇 |
2005年 | 130篇 |
2004年 | 87篇 |
2003年 | 101篇 |
2002年 | 96篇 |
2001年 | 58篇 |
2000年 | 61篇 |
1999年 | 56篇 |
1998年 | 28篇 |
1997年 | 33篇 |
1996年 | 24篇 |
1995年 | 19篇 |
1994年 | 24篇 |
1993年 | 36篇 |
1992年 | 42篇 |
1991年 | 19篇 |
1990年 | 24篇 |
1989年 | 23篇 |
1988年 | 17篇 |
1987年 | 18篇 |
1986年 | 15篇 |
1985年 | 19篇 |
1984年 | 17篇 |
1983年 | 16篇 |
1982年 | 22篇 |
1981年 | 18篇 |
1980年 | 15篇 |
1979年 | 12篇 |
1978年 | 12篇 |
1976年 | 12篇 |
1975年 | 16篇 |
1970年 | 17篇 |
1969年 | 17篇 |
1968年 | 12篇 |
1966年 | 12篇 |
排序方式: 共有2687条查询结果,搜索用时 31 毫秒
1.
2.
H. Mussauer V.L. Sukhorukov A. Haase U. Zimmermann 《The Journal of membrane biology》1999,170(2):121-133
The interaction of human red blood cells (RBCs) with diethylenetriamine-pentaacetic acid (DTPA) or its Gd-complex (Magnevist,
a widely used clinical magnetic resonance contrast agent containing free DTPA ligands) led to the following, obviously interrelated
phenomena. (i) Both compounds protected erythrocytes against electrohemolysis in isotonic solutions caused by a high-intensity
DC electric field pulse. (ii) The inhibition of electrohemolysis was observed only when cells were electropulsed in low-conductivity
solutions. (iii) The uptake of Gd-DTPA by electropulsed RBCs was relatively low. (iv) (Gd-) DTPA reduced markedly deformability
of erythrocytes, as revealed by the electrodeformation experiments using high-frequency electric fields. Taken together, the
results indicate that (Gd-) DTPA produce stiffer erythrocytes that are more resistant to electric field exposure. The observed
effects of the chelating agents on the mechanical properties and the electropermeabilization of RBCs must have an origin in
molecular changes of the bilayer or membrane-coupled cytoskeleton, which, in turn, appear to result from an alteration of
the ionic equilibrium (e.g., Ca2+ sequestration) in the vicinity of the cell membrane.
Received: 19 January 1999/Revised: 1 April 1999 相似文献
3.
Albrecht Grupe Gerhard Spiteller 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1982,230(2):335-344
The heterocyclic drug clomethiazole is metabolized by body passage partly to small aliphatic molecules. The occurrence of such unexpected metabolites is usually overlooked. An appropriate method for their detection is the comparison of urine profiles during drug intake and after withdrawal of the drug. 相似文献
4.
5.
6.
7.
8.
Differences in water binding were measured in the leaf cells ofMesembryanthemum crystallinum L. plants grown under high-salinity conditions by using nuclear-magnetic-resonance (NMR) imaging. The 7-Tesla proton NMR imaging system yielded a spatial resolution of 20·20·100 m3. Images recorded with different spin-echo times (4.4 ms to 18 ms) showed that the water concentrations in the bladder cells (located on the upper and lower leaf surface), in the mesophyll cells and in the water-conducting vessels were nearly identical. All of the water in the bladder cells and in the water-conducting vessels was found to be mobile, whilst part of the water in the mesophyll cells was bound. Patches of mesophyll cells could be identified which bound water more strongly than the surrounding mesophyll cells. Optical investigations of leaf cross-sections revealed two types of mesophyll cells of different sizes and chloroplast contents. It is therefore likely that in the small-sized mesophyll cells water is strongly bound. A long-term asymmetric water exchange between the mesophyll cells and the bladder cells during Crassulacean acid metabolism has been described in the literature. The high density of these mesophyll cells in the lower epidermis is a possible cause of this asymmetry.Abbreviations CAM
Crassulacean acid metabolism
- NMR
nuclear magnetic resonance
- TE
spin-echo time 相似文献
9.
10.
The vegetation of seasonally flooded savannas iin the tropical lowland of the Departamento La Paz, northern Bolivia, was studied. A first collection of vascular plants in this area includes about 600 species, at least three of which are new to the Bolivian flora and four are new to science. The eight major vegetation types distinguished within the savannas are dry bunchgrass savanna (“altura”), seasonally flooded bunch-grass community (“sartenejal”), palm swamp (“palmar”), two types of river floodplains (”bajíos”), a tall shrub community (“chaparral”), the vegetation of termite mounds, and gallery forest. The study area is among the least known in Bolivia. There is a strong need for further studies of these savannas. 相似文献