全文获取类型
收费全文 | 12175篇 |
免费 | 720篇 |
国内免费 | 231篇 |
出版年
2023年 | 88篇 |
2022年 | 79篇 |
2021年 | 181篇 |
2020年 | 254篇 |
2019年 | 229篇 |
2018年 | 297篇 |
2017年 | 237篇 |
2016年 | 242篇 |
2015年 | 346篇 |
2014年 | 412篇 |
2013年 | 585篇 |
2012年 | 298篇 |
2011年 | 343篇 |
2010年 | 305篇 |
2009年 | 451篇 |
2008年 | 462篇 |
2007年 | 519篇 |
2006年 | 494篇 |
2005年 | 463篇 |
2004年 | 430篇 |
2003年 | 408篇 |
2002年 | 427篇 |
2001年 | 342篇 |
2000年 | 312篇 |
1999年 | 289篇 |
1998年 | 224篇 |
1997年 | 217篇 |
1996年 | 240篇 |
1995年 | 234篇 |
1994年 | 241篇 |
1993年 | 233篇 |
1992年 | 225篇 |
1991年 | 234篇 |
1990年 | 209篇 |
1989年 | 236篇 |
1988年 | 234篇 |
1987年 | 214篇 |
1986年 | 196篇 |
1985年 | 229篇 |
1984年 | 293篇 |
1983年 | 178篇 |
1982年 | 287篇 |
1981年 | 229篇 |
1980年 | 162篇 |
1979年 | 121篇 |
1978年 | 50篇 |
1977年 | 68篇 |
1976年 | 26篇 |
1974年 | 14篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
F. -W. Bentrup 《European biophysics journal : EBJ》1980,6(3):175-189
This review treats some examples of electrogenic transport across the outer plasmamembrane (plasmalemma) of plant cells. The selection includes primary active uniport by membrane ATPases (e.g., the proton pump), secondary active transport of hexoses by proton-dependent cotransport, and passive uniport of amines. Primacy is given to the presentation of electrophysiological data and to the discussion of voltage-dependence of the transport mechanisms.Lecture from the Annual Meeting of the Deutsche Gesellschaft für Biophysik at Konstanz 相似文献
42.
Résumé Nous avons montré par une technique autoradiographique que les ions Cl– et Na+ sont concentrés dans les cellules à chlorure de la branchie d'anguille adaptée à l'eau de mer. La signification de cette accumulation ionique plus marquée vers le pôle apical de ces cellules a été discutée par rapport à l'excrétion branchiale de ces ions en eau de mer.
Autoradiographic localization of Cl– and Na+ ions in the chloride cells of sea water adapted eel (Anguilla anguilla L.) gills
Summary With an autoradiographic technique Cl– and Na+ ions have been shown to be localized in the chloride cells of sea water eel gills. The significance of this accumulation, more marked towards the apical pole of these cells, is discussed with regard to branchial excretion of these ions in sea water.相似文献
43.
44.
45.
Jeroen R.P.M. Strating Gerard J.M. Martens 《Biology of the cell / under the auspices of the European Cell Biology Organization》2009,101(9):495-509
The secretory pathway is of vital importance for eukaryotic cells and has a pivotal role in the synthesis, sorting, processing and secretion of a large variety of bioactive molecules involved in intercellular communication. One of the key processes in the secretory pathway concerns the transport of cargo proteins from the ER (endoplasmic reticulum) to the Golgi. Type‐I transmembrane proteins of ~24 kDa are abundantly present in the membranes of the early secretory pathway, and bind the COPI and COPII coat complexes that cover vesicles travelling between the membranes. These p24 proteins are thought to play an important role in the selective transport processes at the ER—Golgi interface, although their exact functioning is still obscure. One model proposes that p24 proteins couple cargo selection in the lumen with vesicle coat recruitment in the cytosol. Alternatively, p24 proteins may furnish subcompartments of the secretory pathway with the correct subsets of machinery proteins. Here we review the current knowledge of the p24 proteins and the various roles proposed for the p24 family members. 相似文献
46.
N. E. Belyaeva V. Z. Pashchenko G. Renger G. Yu. Riznichenko A. B. Rubin 《Biophysics》2006,51(6):860-872
A mathematical model of photosystem II (PSII) events was used to analyze chlorophyll fluorescence transients in the time domain from 100 ns to 10 s after excitation with a saturating 10-ns flash, applied as a part of specialized illumination protocol, using preparations of a thermophilic strain of the unicellular green alga, Chlorella pyrenoidosa Chick (using both intact and diuron-treated cells). Analysis of simulation results has proven that particular attention should be given to flash-induced recombination processes, including nonradiative recombination in PSII, while subsequent charge transfer along the electron transport chain of thylakoid membrane can be adequately described by a single reaction of quinone reoxidation. The PSII model was extended by taking inhibition by diuron of the electron transport in the acceptor side of PSII into account, which allowed simulation of fluorescence induction curves observed in the presence of this inhibitor. The model parameters were determined (stromal pH, rate constants of nonradiative recombination, and the initial reduction state of the quinone pool) which provided adequate simulation of experimentally observed ratios of the maximal and initial fluorescence levels (F m/F 0). 相似文献
47.
Alexander P.R. Theuvenet Willem M.H. Van De Wijngaard Josephus W. Van De Rijke George W.F.H. Borst-Pauwels 《生物化学与生物物理学报:生物膜》1984,775(2):161-168
The applicability of 9-aminoacridine as a probe of the surface potential of yeast cells is examined. Yeast cells are found to quench the fluorescence of the dye and it is shown that this quenching is caused by a decrease in the dye concentration in the bulk aqueous phase. Consistent with predictions of the Gouy-Chapman theory the dye is displaced from the surface of the yeast cells by addition of salts, the effectiveness of the salts being related to the valency of the cation: . It is shown that 9-aminoacridine is predominantly bound by the plasma membrane of the cells. Only a minor part of the binding occurs in the cell wall, in line with the finding that enzymic removal does not significantly affect the binding of the dye to the cells. A single relationship for the distribution ratio of the dye between cells and medium with the ζ potential of the cells is found, irrespective of the way the ζ potential is changed, either by varying the pH or the Ca2+ concentration. It is argued that the electrostatic potentials probed by the dye are much higher than the corresponding ζ potentials and are of the same order of magnitude of the presumed discrete charge potentials experienced by cation transporters in the plasma membrane. It is concluded that 9-aminoacridine may be applied as a convenient and almost quantitative probe of the surface potential that effects the kinetics of ion uptake by the yeast cells. 相似文献
48.
Phosvitin (PV), a subunit of a female-specific protein, vitellogenin, binds to oocyte membranes with a KD of 10?6 M. Binding reaches equilibrium within 30 min after incubation at 25°C. Bound 125I-PV dissociates from the membrane with a t1/2 of 13 h when incubated in buffer. However, when 125I-PV-labeled membranes are incubated in buffer containing 10?5 M unlabeled PV, 50% of the initially bound 125I-PV dissociates from the membrane within 10 min. These results support the conclusion that PV binds to a membrane-associated receptor. Solubilization studies show that Triton X-100 solubilizes up to 45% of the total membrane-bound 125I-PV. Gel-exculsion chromatography of the solubilized material yields a 500,000 dalton 125I-PV-containing complex separated from free 125I-PV. The 500,000 dalton complex completely dissociates to yield free 125I-PV when incubated with excess unlabeled PV. However, when incubated with (1) no addition, (2) IgG, or (3) serum albumin, the extent of dissociation is significantly reduced and is consistent with that which would be predicted on the basis of the observed dissociation rate in the absence of unlabeled PV. These results suggest that bound 125I-PV can only be displaced by unlabeled PV. These results also indicate that the 500,000 dalton species is a solubilized PV-receptor complex and that it is possible to solubilize the PV-receptor in an active form. 相似文献
49.
Torben Clausen Tove Lindahl Andersen Marianne Stürup-Johansen Olga Petkova 《生物化学与生物物理学报:生物膜》1981,646(2):261-267
(1) The effects of vanadate of hexose transport, 45Ca-exchange and (Na+, K+)-contents have been characterized in isolated adipose tissue and skeletal muscles of the rat. (2) In whole epididymal fat pads, vanadate (0.5–5.0 mM) markedly stimulated the uptake of 2-deoxyl[14C]glucose as well as the efflux of . (3) Within the same concentration range, vanadate induced an early increase in 45Ca-washout from preloaded fat pads. The maximum increases in the fractional losses of and 45Ca were significantly correlated (, ). (4) In extensor digitorum longus and soleus muscles, vanadate (0.5–5.0 mM) stimulated the efflux of and this effect was preceded by a rise in the washout of 45Ca. The maximum increases in the fractional losses of and 45Ca were significantly correlated (, ). (5) In extensor digitorum longus and soleus muscles, vanadate increased K+-contents and decreased Na+ contents. (6) The stimulation of 45Ca-washout presumably reflects an increase in the cytoplasmic Ca2+ level, brought about by an inhibitory effect of vanadate on the Ca2+-sensitive ATPase of the sarcoplasmic or the endoplasmic reticulum. As demonstrated for most other insulin-like agents (Sørensen, S.S., Christensen, F. and Clausen, T. (1980) Biochim. Biophys. Acta 602, 433–445), the stimulating effect of vanadate on glucose transport appears to be associated with or mediated by a rise in the cytoplasmic Ca2+ level. 相似文献
50.
Dr. A. Livingston 《Cell and tissue research》1977,180(2):253-261
Summary The microtubules in the neurosecretory neurones of the posterior pituitary were studied using different electron microscopical techniques. Tannic acid staining indicated that the microtubules had a 13 protofilament substructure similar to that described for microtubules from other tissues and organisms; the dimensions of the microtubules were also similar to that previously reported. Albumen pretreatment clearly showed the microtubules running across axonal swellings, but not continuing across the nerve endings. The only organelles showing possible association with the microtubules were small vesicles and smooth endoplasmic reticulum, no association between hormone granules and microtubules could be seen.
Acknowledgement: The author is grateful to P. Wilks for skilled technical assistance. 相似文献