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Acid and alkaline phosphatase activities in culture liquid and mycelial extract during autolysis were studied in seven fungi of the general Ascomycotina, Basidiomycotina and Zygomycotina. High activities of extracellular and mycelial extract acid phosphatase and lower activities of alkaline phosphatase were found in Ascomycotina, and acid phosphatase was present in Basidiomycotina. In Zygomycotina only mycelial extract alkaline phosphatase activity was detected. A correlation between degree of autolysis, pH and acid phosphatase activity was demonstrated. 相似文献
3.
Circular dichroism of platelet factor 4 总被引:1,自引:0,他引:1
The circular dichroism of platelet factor 4 was investigated and it was found to contain 15% alpha-helix, 25% beta-structure, and the rest of the molecule in unordered conformation. In the presence of heparin, no change in the circular dichroism was observed, suggesting no significant changes in the secondary structure of platelet factor 4 when heparin binds. The CD spectrum of platelet factor 4 was also investigated in the presence of increasing concentrations of guanidine hydrochloride. A two-state transition was observed with midpoints at 0.125 and 2.0 M guanidine hydrochloride. Based on gel filtration studies, the first unfolding transition was correlated with the dissociation of the tetrameric structure. This first unfolding domain was not observed in the presence of heparin, suggesting that heparin stabilizes the tetrameric structure. The second unfolding transition corresponds to the disruption of the overall secondary structure which is generally observed with most proteins. It is concluded that a relatively weak force of attraction holds the tetrameric structure of platelet factor 4 and the dissociation of the subunits is accompanied by loss of some helical secondary structure. 相似文献
4.
M Y Khan N S Jaikaria D A Frenz G Villanueva S A Newman 《The Journal of biological chemistry》1988,263(23):11314-11318
The effects of heparin and various related polysaccharides on the circular dichroic spectra of fibronectin and its 31-kDa NH2-terminal tryptic fragment were studied. These effects were evaluated with respect to (i) spectral features of the native proteins that are sensitive to pH denaturation and breaking of disulfide bonds, (ii) sensitivity of spectral changes to Ca2+, and (iii) the fibronectin-dependent interfacial interaction known as "matrix-driven translocation." We found that native heparin causes an attenuation of the positive CD peak at 228 nm with both the intact protein and the fragment, and causes a small but reproducible red shift in the spectrum of the fragment. All of these changes are analogous to spectral changes seen with denaturation or reduction of the proteins. In contrast to the situation with the intact protein, the heparin-induced spectral changes in the fragment were abolished in the presence of 10 mM Ca2+. Desulfation of heparin lessened or destroyed its ability to induce these changes, and carboxymethylated heparin and dextran sulfate induced different kinds of spectral alterations. Fibronectin and heparin determinants required for the induction of the characteristic spectral shift of the NH2-terminal domain corresponded to those required for matrix-driven translocation, suggesting that the associated conformational change in fibronectin plays a role in this biophysical effect. 相似文献
5.
Monoclonal antibodies directed against protoplasts of soybean cells: analysis of the lateral mobility of plasma membrane-bound antibody MVS- 1 总被引:2,自引:1,他引:1 下载免费PDF全文
A monoclonal antibody (MVS-1) was used to monitor the lateral mobility of a defined component (Mr approximately 400,000) of the plasma membrane of soybean protoplasts prepared from suspension cultures of Glycine max (SB-1 cell line). The diffusion coefficient (D) of antibody MVS-1 bound to its target was determined (D = 3.2 X 10(-10) cm2/s) by fluorescence redistribution after photobleaching. Pretreatment of the protoplasts with soybean agglutinin (SBA) resulted in a 10-fold reduction of the lateral mobility of antibody MVS-1 (D = 4.1 X 10(-11) cm2/s). This lectin-induced modulation could be partially reversed by prior treatment of the protoplasts with either colchicine or cytochalasin B. When used together, these drugs completely reversed the modulation effect induced by SBA. These results have refined our previous analysis of the effect of SBA on receptor mobility to the level of a defined receptor and suggest that the binding of SBA to the plasma membrane results in alterations in the plasma membrane such that the lateral diffusion of other receptors is restricted. These effects are most likely mediated by the cytoskeletal components of the plant cell. 相似文献
6.
Microtubule-associated protein MAP2 preferentially binds to a dA/dT sequence present in mouse satellite DNA 总被引:7,自引:0,他引:7 下载免费PDF全文
Avila J Montejo de Garcini E Wandosell F Villasante A Sogo JM Villanueva N 《The EMBO journal》1983,2(8):1229-1234
Microtubule-associated protein MAP2 binds to the Sau96.1 restriction monomer fragment of mouse satellite DNA. This fragment is also present in a lower proportion in bulk DNA. The digestion of MAP2-Sau96.1 fragment complex by DNase results in the protection of certain nucleotide sequences. The sequence poly(dA)4/poly(dT)4 is mainly protected against DNase digestion. 相似文献
7.
Transient exposure of mycelia from Aspergillus niger and Aspergillus nidulans to the cytidine analog 5-azacytidine, leading to no more than 0.3 to 0.5% substitution for cytosine by 5-azacytosine in A. nidulans DNA, resulted in the conversion of a high fraction of the cell population (more than 20%) to a mitotically and meiotically stable "fluffy" developmental phenotype. The phenotypic variants are characterized by the developmentally timed production of a profuse fluffy network of undifferentiated aerial hyphae that seem to escape signals governing vegetative growth. Genetic analysis with six different fluffy clones reveals that this trait is not cytoplasmically coded, is recessive in heterozygous diploids but codominant in heterokaryons, and exhibits a 1:1 Mendelian segregation pattern upon sexual sporulation of heterozygous diploids. Complementation and mitotic haploidization studies indicated that all variants are affected in the same gene, which can be tentatively located on chromosome VIII of A. nidulans. Molecular analysis to search for modified bases showed that DNA methylation is negligible in in both A. niger and A. nidulans and that no differences could be detected among DNAs from wild-type cells, fluffy clones, or mycelia exposed to 5-azacytidine. It thus appears that high-frequency conversion of fungal mycelia to a stable, variant developmental phenotype by 5-azacytidine is the result of some kind of target action on a single nuclear gene and that this conversion can occur in organisms virtually devoid of DNA methylation. 相似文献
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Structural and immunological studies on the protoplast membrane of the yeast Candida utilis 总被引:2,自引:1,他引:1 下载免费PDF全文
C Garcia Mendoza M D Garcia Lopez F Uruburu J R Villanueva 《Journal of bacteriology》1968,95(6):2393-2398
Cell membranes of the yeast Candida utilis isolated by lysis of protoplasts have been shown to be lipoprotein in nature. Electron microscopy shows that Mg++ is responsible for maintaining the integrity of the membrane. A close serological relationship was found between membranes and cell walls isolated from the yeast. This relationship was exhibited not only by membranes obtained by strepzyme treatment but also by those obtained from the action of helicase enzyme. No such relationship existed between membranes and whole cells. Related data have been obtained by treatment of yeasts with different digestive enzymes. All of the results suggest that the protoplast membrane possesses traces of structural cell wall material. This material is detectable by serological tests, but not by electron microscopy. 相似文献