全文获取类型
收费全文 | 376410篇 |
免费 | 41486篇 |
国内免费 | 274篇 |
出版年
2018年 | 3700篇 |
2017年 | 3541篇 |
2016年 | 5128篇 |
2015年 | 7282篇 |
2014年 | 8349篇 |
2013年 | 11696篇 |
2012年 | 13364篇 |
2011年 | 13340篇 |
2010年 | 8809篇 |
2009年 | 7723篇 |
2008年 | 11534篇 |
2007年 | 11953篇 |
2006年 | 11231篇 |
2005年 | 10822篇 |
2004年 | 10797篇 |
2003年 | 10358篇 |
2002年 | 10268篇 |
2001年 | 15591篇 |
2000年 | 15618篇 |
1999年 | 12600篇 |
1998年 | 4587篇 |
1997年 | 4613篇 |
1996年 | 4388篇 |
1995年 | 4222篇 |
1994年 | 4232篇 |
1993年 | 4069篇 |
1992年 | 10528篇 |
1991年 | 10056篇 |
1990年 | 9868篇 |
1989年 | 9570篇 |
1988年 | 8894篇 |
1987年 | 8506篇 |
1986年 | 7713篇 |
1985年 | 7810篇 |
1984年 | 6489篇 |
1983年 | 5689篇 |
1982年 | 4559篇 |
1981年 | 4070篇 |
1980年 | 3801篇 |
1979年 | 6541篇 |
1978年 | 4903篇 |
1977年 | 4584篇 |
1976年 | 4230篇 |
1975年 | 4640篇 |
1974年 | 4975篇 |
1973年 | 5016篇 |
1972年 | 4672篇 |
1971年 | 4350篇 |
1970年 | 3653篇 |
1969年 | 3565篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
Characterization of the specific binding of rat apolipoprotein E-deficient HDL to rat hepatic plasma membranes 总被引:1,自引:0,他引:1
We have used a preparation of rat liver plasma membranes to study the binding of rat apolipoprotein E-deficient HDL to rat liver. The membranes were found to bind HDL by a saturable process that was competed for by excess unlabeled HDL. The binding was temperature-dependent and was 85% receptor-mediated when incubated at 4, 22 and 37 degrees C. The affinity of the binding site for the HDL was consistent at all temperatures, while the maximum binding capacity increased at higher temperatures. The specific binding of HDL to the membranes did not require calcium and was independent of the concentration of NaCl in the media. The effect of varying the pH of the media on HDL binding was small, being 30% higher at pH 6.5 than at pH 9.0. Both rat HDL and human HDL3 were found to compete for the binding of rat HDL to the membranes, whereas rat VLDL remnants and human LDL did not compete. At 4 degrees C, complexes of dimyristoylphosphatidylcholine (DMPC) and apolipoproteins A-I, A-IV and the C apolipoproteins, but not apolipoprotein E, competed for HDL binding to the membranes. At 22 and 37 degrees C, all DMPC-apolipoprotein complexes competed to a similar extent, DMPC vesicles that contained no protein did not compete for the binding of HDL. These results suggest that the rat liver possesses a specific receptor for apolipoprotein E-deficient HDL that recognizes apolipoproteins A-I, A-IV and the C apolipoproteins as ligands. 相似文献
952.
The paper presents the results of theoretical and experimental studies of the radiative properties of plasmas produced by
heating and compression of various materials to high energy densities. The specific features of the theoretical plasma model
known as the ion model, which is used to calculate the radiative characteristics of plasmas of complex chemical composition,
are discussed. The theoretical approach based on this model is applied to the plasma produced during the explosion of the
X-pinch wires. The theoretical estimate of the radiation efficiency is compared with the experimental data on the total energy
yield from an X-pinch made of two different wires (NiCr and Alloy 188). The radiative characteristics of (C12 H16 O8) and
(C8 H12 O6) plasmas are calculated for the temperature diagnostics of plasmas produced from porous targets employed in inertial
confinement fusion experiments with the use of laser radiation and heavy-ion beams. 相似文献
953.
954.
955.
956.
957.
L V Lyzlova B L Vo?tsekhovski? K B Grabovskaia A A Totolian 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1989,(7):7-12
The work shows that fibronectin obtained from human plasma is capable of binding with streptococci of different groups with almost equal effectiveness. Fibronectin bound to bacterial cells inhibits the adhesion of group A streptococci onto vaginal cells, but it produces no effect on the adhesion of group B streptococci. The binding constant of fibronectin 125I is equal to 10(6) -M-1, which indicates that the level of the specificity of interaction is not sufficiently high. 相似文献
958.
Summary. Blood samples from a female sheep-goat hybrid and its back-cross male offspring were tested for electrophoretic variants of plasma albumin, transferrin and esterase, and of red cell carbonic anhydrase, nucleoside phosphorylase, NADH-diaphorase, 'X'-protein, superoxide dismutase, malic enzyme and haemoglobin. Red cells were also tested for blood group antigens. Both animals showed variants that could not be attributed to either sheep or goat alone, thus confirming previous chromosomal data that the female was a genuine sheep-goat hybrid. 相似文献
959.
The compound p-mercuribenzenefulfonate was found to affect the self-association behavior of both spectrin and actin. The reagent brings about the depolymerization of F-actin, as judged from the decrease in the fluorescence of an attached pyrene label, with a second-order rate constant an order of magnitude less than that for the disruption of isolated erythrocyte cytoskeletons. Therefore, it is unlikely that the depolymerization of actin is the rate-determining step in the mercurial-dependent disruption of the erythrocyte cytoskeleton. Low reagent concentrations caused an initial rapid dissociation of spectrin tetramers at a rate comparable with that of cytoskeleton disruption. Prolonged incubation, or higher reagent concentrations, resulted in subsequent aggregation of spectrin. The reagent also prevented the interaction between spectrin and actin, presumably through its depolymerization of actin and its effects on spectrin. The early event in the disruption of isolated erythrocyte cytoskeletons by p-mercuribenzenesulfonate thus appears to be the dissociation of spectrin oligomers. Subsequent depolymerization of actin brought about by the reagent then results in total disruption of the cytoskeleton. 相似文献
960.