全文获取类型
收费全文 | 139859篇 |
免费 | 9377篇 |
国内免费 | 37篇 |
出版年
2022年 | 800篇 |
2021年 | 1767篇 |
2020年 | 1359篇 |
2019年 | 1442篇 |
2018年 | 2976篇 |
2017年 | 2657篇 |
2016年 | 3895篇 |
2015年 | 5760篇 |
2014年 | 5952篇 |
2013年 | 7888篇 |
2012年 | 9592篇 |
2011年 | 8888篇 |
2010年 | 5809篇 |
2009年 | 4685篇 |
2008年 | 7290篇 |
2007年 | 7118篇 |
2006年 | 6896篇 |
2005年 | 6361篇 |
2004年 | 6309篇 |
2003年 | 5794篇 |
2002年 | 5523篇 |
2001年 | 2725篇 |
2000年 | 2413篇 |
1999年 | 2170篇 |
1998年 | 1482篇 |
1997年 | 1037篇 |
1996年 | 1098篇 |
1995年 | 1030篇 |
1994年 | 996篇 |
1993年 | 952篇 |
1992年 | 1441篇 |
1991年 | 1292篇 |
1990年 | 1202篇 |
1989年 | 1289篇 |
1988年 | 1128篇 |
1987年 | 1086篇 |
1986年 | 1025篇 |
1985年 | 1140篇 |
1984年 | 1063篇 |
1983年 | 918篇 |
1982年 | 911篇 |
1981年 | 818篇 |
1980年 | 761篇 |
1979年 | 905篇 |
1978年 | 783篇 |
1977年 | 772篇 |
1975年 | 800篇 |
1974年 | 858篇 |
1973年 | 814篇 |
1969年 | 725篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
[3H]Piflutixol binding to rat striatal membrane preparations identifies both D-1 and D-2 sites. We used [3H]piflutixol to characterise those binding sites present in 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS)-solubilised rat striatal preparations. The specific binding of [3H]piflutixol, as defined using cis-flupenthixol, to CHAPS-solubilised rat striatal tissue was saturable and of high affinity. Specific [3H]piflutixol binding to the solubilised preparations was displaced stereoselectively by the isomers of butaclamol and to an equal extent by both cis-flupenthixol and (+/-)-sulpiride. A positive correlation was found between the capacity of a range of drugs to displace [3H]piflutixol binding and the displacement of [3H]spiperone to the same preparations. The Bmax of [3H]piflutixol binding was not different from that of [3H]spiperone binding to the same preparation. These studies suggest that, in contrast to specific binding of membrane preparations, the specific binding of [3H]piflutixol to CHAPS-solubilised preparations involves mainly D-2 sites. Specific [3H]piflutixol binding, in contrast to [3H]spiperone binding, showed only slow dissociation from soluble preparations. The binding of [3H]piflutixol to CHAPS-solubilised preparations was retained during passage through a gel filtration column. This prelabelling of solubilised striatal preparations using [3H]piflutixol may aid in the purification of CHAPS-solubilised rat striatal D-2 sites. 相似文献
992.
Data are presented on the aboveground and underground biomass of the speciesMarsilea quadrifolia and on the water regime and soil conditions in a habitat of this species in Central Europe (Czechoslovakia). 相似文献
993.
Cells subjected to the events occurring before, during, and after freezing and thawing are exposed to major changes in the
osmotic pressure of the surrounding medium; i.e., the osmolalities can exceed 30. An important question in understanding the
mechanisms of injury is whether cells respond as ideal osmometers to these strongly anisotonic solutions. Mouse and bovine
embryos from eight-cell to blastocyst stage were used to investigate the question. They were found to behave as ideal osmometers
at room temperature over a wide range of tonicities; i.e., from four times isotonic to almost 1/3 times isotonic, ideality
being defined by a Boyle-van't Hoff equation. Embryo volumes increased from 40 to 200% of isotonic over this range and survivals
of mouse embryos were unaffected. However, outside this range the membrane apparently becomes leaky and the survival of mouse
embryos drops sharply. Osmolalities rise to high values during freezing and the paper develops the thermodynamic equations
to show how computed cell volumes as a function of subzero temperature can be translated into the Boyle-van't Hoff format
of cell volume as a function of the reciprocal of osmolality. 相似文献
994.
995.
996.
997.
998.
Corynebacterium (Eubacterium) suis strains from boars and sows haemagglutinated erythrocytes of different animal species (calf, guinea pig, poultry, pig, and human). The haemaigglutination was man nose resistant (MR) and was neither inhibited by L-fucose nor D-galactose. The hydrophobicity measured by salt aggregation test (0.1–0.9 mol/1 (NH4)2SO4) and the hydrophobic interaction chromatography test (90 % retention in octyl sepharose) together with the haemagglutinating activity, indicated the presence of fimbriae on the bacteria. The haemagglutinating and hydrophobic properties were heat-sensitive (60°C for 10 min) suggestive of the presence of a protein structure. Two types of fimbria-tion were demonstrated by electron microscopy. Fetuin and glyco^ protein inhibited the haemagglutination, whereas porcine mucin was without any effect. These results indicate that branched glycoproteins might be important receptors for these fimbriae. The pathogenic aspects of C. suis are discussed, based on recent acquired knowledge of the effect of other pyelonephritogenic bacteria. 相似文献
999.
Interrelationships between the phase diagrams of the two-component phospholipid bilayers 总被引:1,自引:1,他引:0
下载免费PDF全文
![点击此处可从《Biophysical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Basic relationships between the phase diagrams, previously considered independent of each other, are described. Phase diagrams of two-component phosphatidylcholine/phosphatidylcholine (PC/PC), phosphatidylethanolamine/phosphatidylethanolamine (PE/PE), and PC/PE lipid membranes are systematically investigated by means of the Landau theory. While gradually changing the chain length of one of the components, a characteristic peritectic-miscible-azeotropic-semiazeotropic-eutectic (P-M-A-S-E) series of the phase diagram was found in the PC/PE system and a peritectic-miscible-one-component-miscible-peritectic (P-M-O-M-P) series was found in the PC/PC and PE/PE systems. These serial catastrophic changes in the phase diagrams could be explained by the fusion and birth of the mixed phase regions in the phase diagram. Finally when we constructed the superdiagrams, we obtained all of the possible series of the phase diagrams in a wide class of the two-component mixtures. Moreover, one can predict the type of the phase diagram when the components r and p contain equal-length saturated hydrocarbon chains.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
1000.