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51.
Z. Krupa 《Photosynthesis research》1983,4(3):229-239
Thylakoid membranes obtained from bean chloroplasts treated with bean galactolipase or phospholipase A2 (from Crotalus terr. terr.) showed marked changes in their polypeptide patterns when separated on SDS-PAGE. The obtained results have been discussed with regard to the relationship between chloroplast lipids and polypeptides originating from chlorophyll-protein complexes of bean thylakoids. A coexistence between galactolipids and the peripheral antennae in PS I complex and LHCP3 as well as a conspicuous role of phospholipids in PSI and PSII centre chlorophyll-protein complexes has to be underlined.Abbreviations CP1
chlorophyll a-protein complex of PSI
- CPa
chlorophyll a-protein complex of PSII
- D10
digitonin subchloroplast particles enriched in PSII
- D144
digitonin subchloroplast particles enriched in PSI
- DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- LHCP1–3
light harvesting chlorophyll a/b protein complexes
- PAGE
polyacrylamide gel electrophoresis
- PSI
photosystem I
- PSII
photosystem II
- SDS
sodium dodecyl sulphate
- TCA
trichloroacetic acid
- Tricine
N-Tris-(hydroxymethyl)-methylglycine
- Tris
Tris-(hydroxymethyl)-aminomethan 相似文献
52.
The electrical conductivity of bilayer lipid membranes (BLM) of oxidized cholesterol has been measured separately in bathing solutions of sodium sulphate, sodium chloride, sodium bromide, sodium iodide and also in bathing solutions of iodine and iodine containing these salts. An attempt has been made to explain the conduction of electric current across the membranes. 相似文献
53.
J M Pages 《Biochimie》1983,65(10):531-541
Bacterial protein synthesis takes place in the cytoplasm, thus periplasmic and outer membrane proteins pass through the cytoplasmic membrane during their dispatch to the cell envelope. The exported proteins are synthesized as precursor that contains an extra amino-terminal sequence of amino-acids. This sequence, termed "signal sequence", is essential for transport of the envelope proteins through the inner membrane and is cleaved during the exportation process. Various hypotheses for the mechanism have been presented, and it is likely that no signal model will be suitable to the export of all cell envelope proteins. This review is focused on the relationship between the cytoplasmic membrane and the precursor form. The physiological state of the membrane - fluidity, membrane potential for instance - is the strategic requirement of exportation process. Precursors can be accumulated in whole cells with various treatments which alter the cytoplasmic membrane. This inhibition of processing is obtained by modification of unsaturated to saturated fatty acids ratio or with phenylethyl alcohol which perturbs the membrane fluidity, with uncoupler agents such as carbonyl cyanide m-chlorophenyl hydrazone which dissipate the proton motive force, or with hybrid proteins which get jamming in the membrane. However, little is known about the early steps of translocation process across the cytoplasmic membrane ; for instance, it is not clear yet whether energy is required for either or both of the first interaction membrane-precursor and the crossing through the membrane. Several studies have recently shown the presence of exportation sites and of proteins which might play a prominent role in the export process, but the mechanism of discrimination between outer membrane proteins and periplasmic proteins is unknown. Considerable work has been done by genetic or biochemical methods and we have now the first lights of the expert mechanism. 相似文献
54.
R. Dermietzel 《Cell and tissue research》1974,149(1):121-135
Summary Fixed and unfixed astrocytic membranes from the CNS of the cat were studied by means of the freeze-etching technique.A variable number of gap junctions was detected in astrocytic membranes. They are characterized by the well known hexagonal composition of their subunits. Besides this type of highly ordered membrane-bound particles, a second one was found. It is composed of four single particles (diameter 5 nm) which form an orthogonal subunit with a side length of about 10 nm. These membrane-associated orthogonal particle complexes (MOPC) could be observed in different stages of aggregation and expansion. They reveal an accumulation in membranes of the marginal glia layers and in the perivascular astrocytic end-feet. Unfixed, glycerol treated membranes, however, do not show these structures. After glycerol treatment of the unfixed membranes by immersion, the MOPC disintegrate to single particles which form clusters of various extension. The clustering phenomenon is dependent on the length of the time of exposure to glycerol. Shortening of the glycerol treatment by intravasal perfusion of the cryoprotectant agent causes an decrease of the clusters. Fragments and transient forms of the MOPC become visible. By variation of different physico-chemical parameters of the washing solution a similar effect on the MOPC was not achieved. The discussion deals with probable functional aspects of the MOPC. They are considered to act as membrane-bound functional multienzyme complexes which a) might play a role in mediating transmembrane passage of metabolites, or b) are essential for CSF control mechanisms, or c) have a functional relation to the nexus.Presented in part at the IIIth European Congress of Anatomists, Manchester, September 1973.Supported by Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 114(Bionach). 相似文献
55.
An unusual ultrastructural association of smooth membranes and glycogen particles: The glycogen body
Yvi J. Le Beux 《Cell and tissue research》1969,101(3):433-447
Summary An electron microscope study of the epithelium of rabbit fallopian tube demonstrated a rarely described intracytoplasmic structure consisting of an array of smooth membranes associated with glycogen particles. This organelle is seen exclusively in the ciliated cells. A three-dimensional reconstruction of these glycogen bodies has been made from serial sections. The peripheral localization of the rough-surfaced membranes in continuity with intra-corpuscular smooth membranes, which have lost their granules, suggests a possible role for the rough membranes in the genesis of the smooth membranes of these glycogen bodies. The role of both the smooth and the rough membranes in glycogenesis and glycogenolysis is discussed.This investigation was made in part in the Laboratoire d'Hormonologie et de Cytologie Expérimentale, Hôpital Broca, Paris. 相似文献
56.
Metastasis is a major, life-threatening complication of cancer. The bloodstream is the most important disseminative route
for cancer cells liberated from their parent tumors. Single circulating cancer cells are arrested in the microvasculature,
where the vast majority are killed by rapid or slow processes, and the relatively few survivors grow into micrometastases.
We review the underlying causes of one type of rapid cancer cell death in the microcirculation, namely, that caused by biomechanical
interactions of cancer cells with microvessel walls, which may result in cell surface membrane expansion and lethal rupture.
These lethal interactions appear to be important rate-regulators in hematogenous metastasis, and to dictate some aspects of
metastatic patterns. Although these are not the only interactions involving cancer cells, in contrast to others involving
cellular and humoral defense mechanisms, they have received comparatively little attention. 相似文献
57.
柳海林 《Virologica Sinica》1989,(2)
我们的实验结果揭示流行性出血热病毒(EHFV)在酸性条件下可导致感染细胞发生融合,细胞间隙消失,细胞界限不清,细胞和细胞连在一起,形成多核的巨细胞体,姬姆薩染色比未融合细胞浅。融合液(Eagle’s基础培养液,含0.2%BSA,20mmol/L HEPES),用1.0NNaOH调pH至5.0—6.0时,细胞融合最甚,几乎所有的感染细胞都 相似文献
58.
Hubert Wiener Dan A. Klaerke Peter L. Jørgensen 《The Journal of membrane biology》1990,117(3):275-283
Summary In the mammalian distal colon, the surface epithelium is responsible for electrolyte absorption, while the crypts are the site of secretion. This study examines the properties of electrical potential-driven86Rb+ fluxes through K+ channels in basolateral membrane vesicles of surface and crypt cells of the rabbit distal colon epithelium. We show that Ba2+-sensitive, Ca2+-activated K+ channels are present in both surface and crypt cell derived vesicles with half-maximal activation at 5×10–7
m free Ca2+. This suggests an important role of cytoplasmic Ca2+ in the regulation of the bidirectional ion fluxes in the colon epithelium.The properties of K+ channels in the surface cell membrane fraction differ from those of the channels in the crypt cell derived membranes. The peptide toxin apamin inhibits Ca2+-activated K+ channels exclusively in surface cell vesicles, while charybdotoxin inhibits predominantely in the crypt cell membrane fraction. Titrations with H+ and tetraethylammonium show that both high-and low-sensitive86Rb+ flux components are present in surface cell vesicles, while the high-sensitive component is absent in the crypt cell membrane fraction. The Ba2+-sensitive, Ca2+-activated K+ channels can be solubilized in CHAPS and reconstituted into phospholipid vesicles. This is an essential step for further characterization of channel properties and for identification of the channel proteins in purification procedures. 相似文献
59.
Lanfranco Corazzi Giuseppe Fratto Roberto Pistolesi Giuseppe Arienti 《The Journal of membrane biology》1989,112(2):123-129
Summary Liposomes are prepared from rat brain microsomal lipid and loaded with either Tb3+ or dipicolinic acid (DPA) to test fusion with the Tb-DPA assay. They are also loaded with octadecyl Rhodamine B chloride (R18) to test fusion with the R18 assay. The addition of either Ca2+ or Mg2+ to loaded liposomes develops fluorescence with both assays. The fluorescence elicited by Mg2+ is similar to that elicited by Ca2+ if assessed with R18, but much higher if determined by Tb-DPA. The Ca2+-dependent fluorescence of the Tb-DPA complex is not suppressed by the addition of EDTA, and therefore it is internal to vesicles. The contrary is true for the Mg2+-dependent fluorescence. Rat brain microsomes can be disrupted by adding octylgucoside and reconstituted by removing it by dialysis. We use this procedure to load microsomes with DPA. This allows the use of the Tb-DPA assay for testing the fusion of rat brain microsomes. Reconstituted microsomes fuse with liposomes. This fusion has characteristics similar to those of liposome-liposome fusion. However, no microsome-microsome fusion could be detected with either method. The two methods give different results, owing to the chemical properties of the assays. Indeed Tb-DPA implies the retention of vesicle content, whereas this is not required by the R18 assay. 相似文献
60.
The expression of a highly expressed Bacillus subtilis gene is not reduced by introduction of multiple codons normally not present in such genes 总被引:1,自引:0,他引:1
Charles A. Loshon Federico Tovar-Rojo Susan E. Goldrick Peter Setlow 《FEMS microbiology letters》1989,65(1-2):59-63
A recombinant DNA Proteus mirabilis L-form expression system, LVI (pJS127), was used to synthesize human fusion interferon alpha 1 (f-IFN-alpha 1). In the expression plasmid used, the complete coding sequence of IFN-alpha 1 was linked to the streptococcal speA promoter and the 5' end of the speA structural gene including its signal sequence coding region. LVI (pJS127) was capable of complete secretion into the culture medium of biologically active f-IFN-alpha 1 whose identity was confirmed by immunological and chemical evidence. In particular, bacterial L-forms were for the first time shown to be capable of correct signal peptide processing, as determined by N-terminal sequencing of the secreted f-IFN. 相似文献