全文获取类型
收费全文 | 3593篇 |
免费 | 216篇 |
国内免费 | 81篇 |
出版年
2023年 | 50篇 |
2022年 | 52篇 |
2021年 | 89篇 |
2020年 | 103篇 |
2019年 | 91篇 |
2018年 | 111篇 |
2017年 | 90篇 |
2016年 | 86篇 |
2015年 | 94篇 |
2014年 | 173篇 |
2013年 | 235篇 |
2012年 | 96篇 |
2011年 | 170篇 |
2010年 | 109篇 |
2009年 | 149篇 |
2008年 | 155篇 |
2007年 | 143篇 |
2006年 | 165篇 |
2005年 | 175篇 |
2004年 | 163篇 |
2003年 | 142篇 |
2002年 | 136篇 |
2001年 | 83篇 |
2000年 | 53篇 |
1999年 | 73篇 |
1998年 | 89篇 |
1997年 | 60篇 |
1996年 | 56篇 |
1995年 | 58篇 |
1994年 | 70篇 |
1993年 | 39篇 |
1992年 | 49篇 |
1991年 | 40篇 |
1990年 | 64篇 |
1989年 | 38篇 |
1988年 | 38篇 |
1987年 | 48篇 |
1986年 | 20篇 |
1985年 | 31篇 |
1984年 | 45篇 |
1983年 | 21篇 |
1982年 | 30篇 |
1981年 | 27篇 |
1980年 | 18篇 |
1979年 | 19篇 |
1978年 | 11篇 |
1977年 | 6篇 |
1976年 | 10篇 |
1975年 | 4篇 |
1974年 | 5篇 |
排序方式: 共有3890条查询结果,搜索用时 31 毫秒
1.
Reuben S.E. Young Andrew P. Bowman Kaylyn D. Tousignant Berwyck L.J. Poad Jennifer H. Gunter Lisa K. Philp Colleen C. Nelson Shane R. Ellis Ron M.A. Heeren Martin C. Sadowski Stephen J. Blanksby 《Journal of lipid research》2022,63(6):100223
The cellular energy and biomass demands of cancer drive a complex dynamic between uptake of extracellular FAs and their de novo synthesis. Given that oxidation of de novo synthesized FAs for energy would result in net-energy loss, there is an implication that FAs from these two sources must have distinct metabolic fates; however, hitherto, all FAs have been considered part of a common pool. To probe potential metabolic partitioning of cellular FAs, cancer cells were supplemented with stable isotope-labeled FAs. Structural analysis of the resulting glycerophospholipids revealed that labeled FAs from uptake were largely incorporated to canonical (sn-) positions on the glycerol backbone. Surprisingly, labeled FA uptake also disrupted canonical isomer patterns of the unlabeled lipidome and induced repartitioning of n-3 and n-6 PUFAs into glycerophospholipid classes. These structural changes support the existence of differences in the metabolic fates of FAs derived from uptake or de novo sources and demonstrate unique signaling and remodeling behaviors usually hidden from conventional lipidomics. 相似文献
2.
3.
Georg Steinhauser Johannes H. Sterba Karin Poljanc Max Bichler Karl Buchtela 《Journal of trace elements in medicine and biology》2006,20(3):119-153
In this study, 18 partly commercially available samples of rock salt from Austria, Germany, Pakistan, Poland, Switzerland, and Ukraine were investigated with respect to their content of trace elements using instrumental neutron activation analysis. Elements detected were Al, Ba, Br, Ca, Ce, Cl, Co, Cr, Cs, Eu, Fe, Hf, La, Mn, Na, Rb, Sb, Sc, Sm, Sr, Ta, Tb, Th, and Zn, some of them only in individual cases. An estimation of the bioavailability of these trace elements was performed by dissolving an equivalent of the sodium chloride samples in diluted hydrochloric acid (simulating stomach acid), filtering off the insoluble components, and analyzing the evaporated filtrate. It could be shown that in most cases bioactive trace elements like Fe can be found in rock salt in the form of almost insoluble compounds and are therefore not significantly bioavailable, whereas thorium, for example, was partly bioavailable in two cases. A significant contribution to the recommended daily intake of metal trace elements by using rock salt for nutrition can be excluded. 相似文献
4.
Cynomolgus monkey are susceptible to infection with select simian immunodeficiency virus (SIV). We investigated the early interactions between SIV envelope glycoproteins (gp120mac251) and macaque lymphocytes. Our results demonstrate that the soluble viral glycoprotein induce a specific phospholipase A2 (PLA2) activation in lymphocytes through CD4. This PLA2 activation, induced after envelope glycoprotein-CD4 interaction, because of its locally destabilizing membrane effect, may have important implications for preparing the lymphocyte membrane for fusion with the viral particle. However, this effect is not sufficient to accomplish fusion. These data indicate that the specific step of fusion may be downstream from PLA2 activation. 相似文献
5.
Keitaro Sou 《生物化学与生物物理学报:生物膜》2008,1778(4):1035-1041
Anionic vesicles containing acidic phospholipids are known complement activators. To clarify which negative physicochemical electrostatic charges on vesicles and structural specificities of acidic lipids are critical to complement activation, the electrostatic properties and activity to complement of two anionic vesicles modified with a carboxylic acid derivative or a conventional acidic phospholipid were compared. Electrophoretic mobility measurements indicated that the negative zeta potential and the electrostatic interactivity of these two anionic vesicles were equal at pH 7.4. However, the infusion of vesicles containing acidic phospholipid induced significant complement activation, while vesicles containing the carboxylic acid derivative failed to activate complement. These results indicate that the negative charge on the surface of vesicles is not critical for the activation complement, suggesting that complement activation is specific to the structure of acidic groups. This finding is likely to be important to the design of anionic biointerfaces and may support the promising medical applications of this anionic vesicle modified with a carboxylic acid derivative. 相似文献
6.
C-Met expression and mechanical activation of satellite cells on cultured muscle fibers. 总被引:2,自引:0,他引:2
Ashley C Wozniak Orest Pilipowicz Zipora Yablonka-Reuveni Steven Greenway Shauna Craven Elliott Scott Judy E Anderson 《The journal of histochemistry and cytochemistry》2003,51(11):1437-1445
Single-fiber cultures can be used to model satellite cell activation in vivo. Although technical deficiencies previously prevented study of stretch-induced events, here we describe a method developed to study satellite cell gene expression by in situ hybridization (ISH) using protocol modifications for fiber adhesion and fixation. The hypothesis that mechanical stretching activates satellite cells was tested. Fiber cultures were established from normal flexor digitorum brevis muscles and plated on FlexCell dishes with a layer of Vitrogen. After 2 hr of stretch in the presence of BrdU, satellite cells on fibers attached to Vitrogen were activated above control levels. In the absence of activating treatments or mechanical stretch, ISH studies showed 0-6 c-Met+ satellite cells per fiber. Time course experiments demonstrated stable quiescence in the absence of stretch and significant peaks in activation after 30 min and 2 hr of stretch. Frequency distributions for unstretched fiber cultures showed a significantly greater number of quiescent c-Met+ satellite cells than were activated by stretching, suggesting that typical activation stimuli did not trigger cycling in the entire c-Met+ population of satellite cells. These methods have a strong potential to further dissect the nature of stretch-induced activation and gene expression among characterized populations of individual quiescent and activated satellite cells. 相似文献
7.
《Developmental cell》2021,56(16):2329-2347.e6
8.
9.
Charles E. Wenner John C. Cheney L. David Tomei 《Journal of cellular biochemistry》1981,15(2):161-168
The introduction of either PGF2α (10?7 M) or TPA (10?7 M) stimulated, ouabain-sensitive 86Rb+ influx at 30 min in postconfluent 3T3-4 mouse fibroblast cultures by 117% and 124%, respectively. Both TPA and PGF2α at these concentrations stimulated the incorporation of 3H-TdR into DNA. TPA had the greatest stimulatory effect, which was similar to that obtained with 10% fetal calf serum. In accord with the idea that modulation of membrane processes such as Na+/K+ pump activity in fibroblasts may reflect important events related to the initiation of DNA synthesis, it was observed that in both 3T3-4 and C3H-1 0T½ cells there were parallel increases in 3H-TdR incorporation and ouabain-sensitive 86Rb+ influxes with 10?7 M TPA, whereas PGF2α stimulated a significant increase in 3H-TdR incorporation in 3T3-4 but not C3H-10T½ cells and only marginal increases in ouabain-sensitive 86Rb+ influx in both. Therefore, although there appears to be a close correlation between Na+/K+ pump activation and subsequent S-phase entry following TPA stimulation, a similar correlation for PGF2α cannot be confirmed. 相似文献
10.
Harry Le Vine Pedro Cuatrecasas 《Biochimica et Biophysica Acta (BBA)/General Subjects》1981,672(3):248-261
A cytosolic, macromolecular factor required for the cholera toxin-dependent activation of pigeon erythrocyte adenylate cyclase and cholera toxin-dependent ADP-ribosylation of a membrane-bound 43 000 dalton polypeptide has been purified 1100-fold from horse erythrocyte cytosol using organic solvent precipitation and heat treatment. This factor, 13 000 daltons, does not absorb to anionic or cationic exchange resins, is sensitive to trypsin or 10% trichloroacetic acid and is not extractable by diethyl ether. Activation of adenylate cyclase by cholera toxin requires the simultaneous presence of ATP (including possible trace GTP), NAD+, dithiothreitol, cholera toxin, membranes and the cytosolic macromolecular factor. Reversal of cholera toxin activation of adenylate cyclase, and of the toxin-dependent ADP-ribosylation, requires the presence of the cytosolic factor. The ability of the purified cytosolic factor to influence the hormonal sensitivity of liver membrane adenylate cyclase may provide clues to its physiological functions. 相似文献