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991.
4β-Methoxymethyl-4β-demethyl territrem B [5] was synthesized from 4β-hydroxymethyl-β-demethyl territrem B [4] by treatment
with dimethyl sulfate in methanolic NaOH. The structure of 5 was elucidated by uv, nmr and mass spectra. The IC50 of 5 on
acetylcholinesterase (AChE) was 6.30 × 10-5 M, which indicated 0.4% of the anti-AChE activity of territrem B [2].
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
992.
Marco Ligozzi Marco Aldegheri Silvia C. Predari Roberta Fontana 《FEMS microbiology letters》1991,83(3):335-339
Penicillin-binding protein (PBP) 5 of Enterococcus hirae ATCC 9790 belongs to the class of the high-molecular mass, low-affinity PBPs which have been correlated with penicillin resistance in most Enterococcus species. Polyclonal antibodies were raised against PBP 5 and used to detect immunologically related membrane proteins in E. faecium and E. faecalis strains. Several strains of both species were found to have a membrane protein of similar molecular mass to E. hirae PBP 5 which reacted with the antibodies. Some E. faecium strains did not react with antibodies but their derivatives with increased penicillin minimal inhibitory concentrations did. In some E. faecalis strains the lack of a PBP 5-related protein was associated with failure to select stable penicillin-resistant derivatives. 相似文献
993.
Chieko Mineo Yun-Shu Ying Christine Chapline Susan Jaken Richard G.W. Anderson 《The Journal of cell biology》1998,141(3):601-610
Previously, we showed caveolae contain a population of protein kinase Cα (PKCα) that appears to regulate membrane invagination. We now report that multiple PKC isoenzymes are enriched in caveolae of unstimulated fibroblasts. To understand the mechanism of PKC targeting, we prepared caveolae lacking PKCα and measured the interaction of recombinant PKCα with these membranes. PKCα bound with high affinity and specificity to caveolae membranes. Binding was calcium dependent, did not require the addition of factors that activate the enzyme, and involved the regulatory domain of the molecule. A 68-kD PKCα-binding protein identified as sdr (serum deprivation response) was isolated by interaction cloning and localized to caveolae. Antibodies against sdr inhibited PKCα binding. A 100–amino acid sequence from the middle of sdr competitively blocked PKCα binding while flanking sequences were inactive. Caveolae appear to be a membrane site where PKC enzymes are organized to carry out essential regulatory functions as well as to modulate signal transduction at the cell surface. 相似文献
994.
Triguna N. Misra Ram S. Singh Janardan Upadhyay Deo Nath M. Tripathi 《Phytochemistry》1984,23(8):1643-1645
Two new aliphatic hydroxy-ketones, isolated from the rhizomes of Curculigo orchioides, have been characterized as 27-hydroxytriacontan-6-one and 23-hydroxytriacontan-2-one, respectively, by spectral data and chemical studies. 相似文献
995.
Benjamin Yat-Ming Yung Harris Busch Pui-Kwong Chan 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1985,826(4):167-173
To elucidate the possible role of nucleolar phosphoprotein B23 in ribosome synthesis, drugs which inhibit the processing of ribosomal RNA were employed. After treatment with actinomycin D, toyocamycin or high doses of α-amanitin, a uniform nucleoplasmic fluorescence was observed. Low doses of α-amanitin and the protein synthesis inhibitor puromycin and cycloheximide had no effect on protein B23 translocation. By ELISA immunoassay, there was a 60% decrease in the amount of protein B23 in the nucleoli of the actinomycin D-treated cells as compared with the control nucleoli. Conversely, the amount of protein B23 in the nucleoplasm (excluding nucleoli) was 3-fold higher in the actinomycin D-treated cells. Preribosomal ribunucleoprotein particles (pre-rRNPs) were extracted from isolated nucleoli of Novikoff hepatoma ascites cells and fractionated on sucrose density gradients. Protein B23 was found co-localized with the pre-rRNPs as determined by ELISA assays which agrees with previous studies. The proteins in these 80 S and 55 S pre-ribosomal ribonucleoprotein particles were fractionated by 10% gel electrophoresis. Immunoblots showed protein B23 was present in both pre-rRNPs. 相似文献
996.
用LSAB免疫组织化学技术,检测了nm23-H1基因在乳腺癌的表达情况。在143例乳腺癌中,76.2%呈阳性表达。nm23-H1基因表达与患者年龄、肿瘤大小、组织学分类、分级,雌、孕激素受体状态以及p16基因表达无明显相关(P>0.05);但淋巴结转移组阳性率64.1%(41/64)显著低于无转移组83.9%(52/62)(P<0.05),nm23-H1阳性表达组的死亡率35.7%(10/28),也明显低于阴性组55.6%(5/9),提示检测nm23-H1蛋白可能成为乳腺癌患者的一种新的预后指标。nm23-H1和p16基因表达无明显相关性,提示二者可能通过两种不同的机制和途径影响癌转移和预后,联合检测此二种蛋白对判断乳腺癌患者的癌转移和预后更有临床意义。 相似文献
997.
放线菌素23-21微生物检定法及HPLC法比较 总被引:1,自引:0,他引:1
采用微生物检定法测定放线菌素23-21的抗菌活性,检定菌为枯草芽孢杆菌。当放线菌素23-21的浓度为0.91~4.37μg/ml时,其抑菌圈直径与反应剂量有线性关系。经生物学统计分析,实验结果可靠。并与高效液相色谱法(HPLC)进行对照检测,实验结果基本吻合。 相似文献
998.
Marie-Christine Ralet Dominique Fouques Joëlle Leonil Daniel Molle Jean-Claude Meunier 《Journal of Protein Chemistry》1999,18(3):315-323
Protein kinase CK2 purified from the yeast Yarrowia lipolytica was used to phosphorylate soybean -conglycinin subunit. CK2 is known to phosphorylate serines and threonines in the consensus sequence Ser/Thr-X-X-Glu/Asp/SerP/TyrP. -Conglycinin subunit (68 kDa) presents seven consensus sequences, but only 0.5–1 mol P/mol subunit was incorporated by CK2. [32P]Phosphorylated -conglycinin subunit was cleaved either by cyanogen bromide or by trypsin. 32P was incorporated into the largest cyanogen bromide fragment only (50 kDa, N-terminal) and only two radiolabeled zones were detected after HPLC of the trypsic digest. The corresponding phosphorylated zones were collected and further analyzed by RP-HPLC coupled to electrospray ionization mass spectrometry (LC-ESMS). Two phosphorylated sites, Ser 75 and Ser 117, were determined after MS-MS analysis of three phosphopeptides identified as 70–89, 116–126, and 116–127 sequences. Over the seven consensus sequences of -conglycinin subunit, Ser 75 is the only one which was phosphorylated. Ser 117 was phosphorylated although it is not an expected phosphorylation site according to the canonical consensus sequence criteria as there is no acidic determinant at the +3 position. Both Ser 75 and Ser 117 are located inside very acidic sequences, by contrast with the other unphosphorylated potential sites. 相似文献
999.
Genetic basis of macrolide and lincosamide resistance in Brachyspira (Serpulina) hyodysenteriae 总被引:1,自引:0,他引:1
Karlsson M Fellström C Heldtander MU Johansson KE Franklin A 《FEMS microbiology letters》1999,175(2):255-260
Macrolide antibiotic resistance is widespread among Brachyspira hyodysenteriae (formerly Serpulina hyodysenteriae) isolates. The genetic basis of macrolide and lincosamide resistance in B. hyodysenteriae was elucidated. Resistance to tylosin, erythromycin and clindamycin in B. hyodysenteriae was associated with an A-->T transversion mutation in the nucleotide position homologous with position 2058 of the Escherichia coli 23S rRNA gene. The nucleotide sequences of the peptidyl transferase region of the 23S rDNA from seven macrolide and lincosamide resistant and seven susceptible strains of Brachyspira spp. were determined. None of the susceptible strains were mutated whereas all the resistant strains had a mutation in position 2058. Susceptible strains became resistant in vitro after subculturing on agar containing 4 micrograms ml-1 of tylosin. Sequencing of these strains revealed an A-->G transition mutation in position 2058. 相似文献
1000.
Stenomitos terricola FBCC-A190 was collected from soils around the trees of Mt. Gwanggyo, located in Yeongtong-gu, Suwon-si, Gyeonggi-do. S. terricola FBCC-A190 is a thin and simple filament with a cell length that is longer than its width. It has a thin and firm sheath, exhibiting a blue-green color. Species belonging to genus Stenomitos is semi-cryptic species with slight morphological differences from each other. They were confirmed as Stenomitos species by analysis using 16S rRNA and 16S–23S ITS. A monophyletic cluster was formed with the previously reported genus Stenomitos, with 16S rRNA gene sequences sharing similarities of 95.9–97.9% except for S. pantisii TAU-MAC 4318. In addition, 16S–23S ITS gene sequencing showed tRNAAla, tRNAIle and V2, similar to the previously reported genus Stenomitos. From these results, Stenomitos terricola sp. nov. was proposed as a new species belonging to genus Stenomitos. 相似文献