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221.
222.
A simple and rapid slide latex agglutination assay was developed to detect penicillin-binding protein 2′ (PBP2′) from isolates of staphylococi. PBP2′ present in the membranes of methicillin-resistant Staphylococcus aureus (MRSA) or methicillin-resistant coagulase negative staphylococci (MRCNS) was rapidly extracted by alkaline treatment and, by combining with a slide agglutination reaction using latex particles sensitized with monoclonal antibodies raised against it, PBP2′ could be detected from a single loopful of cells taken from agar plates not containing beta-lactum antibiotics within 15 min. In a study of clinical isolates previously characterized as either MRSA or methicillin-susceptible Staphylococcus aureus (MSSA) by antibiotic susceptibility testing, 231 specimens of 232 MRSA were PBP2′ positive by latex agglutination, and the 87 specimens of MSSA were all negative. One specimen identified as MRSA by susceptibility testing but PBP2′ negative by latex agglutination was confirmed as mecA gene negative by PCR. This simple and rapid slide latex reagent should be useful in clinical diagnostics. 相似文献
223.
Tomoo Kamiya A-Hon Kown Toshiki Kanemaki Yoichi Matsui Shouji Uetsuji Tadayoshi Okumura Yasuo Kamiyama 《In vitro cellular & developmental biology. Animal》1998,34(2):131-137
Summary The Anaeropack system for cell culture, which was originally designed for the growth of anaerobic bacteria, was used to produce
a hypoxic atmosphere for cultured hepatocytes. We measured changes in the oxygen and carbon dioxide concentrations and the
atmospheric temperature in an airtight jar. We also measured changes in the pH of the medium during hypoxia to assess the
accuracy of this system. Moreover, we used three durations (2, 3, and 4 h) of hypoxia and 8 h of reoxygenation in cultured
rat hepatocytes, and then measured the lactate dehydrogenase (LDH), ketone body concentration (acetoacetate + β-hydroxybutyrate),
and the ketone body ratio (KBR: acetoacetate/β-hydroxybutyrate) in the medium in order to assess the suitability of this system
as a model for reperfusion following liver ischemia. The oxygen concentration dropped to 1% or less within 1 h. The concentration
of carbon dioxide rose to about 5% at 30 min after the induction of the hypoxic conditions, and was maintained at this level
for 5 h. No effect of the reaction heat produced by the oxygen absorbent in the jar was recognized. The extent of cell injury
produced by changing the hypoxic parameters was satisfactorily reflected by the KBR, the ketone body concentration, and the
LDH activity released into the medium. Because this model can duplicate the conditions of the hepatocytes during revascularization
following ischemic liver, and the Anaeropack system for cell culture is easy to manipulate, it seems suitable for the experimental
study of hypoxic injury and revascularization in vitro. 相似文献
224.
【目的】为齐整小核菌代谢工程研究建立高效的转录单元组装系统。【方法】通过应用Golden Gate技术,以mobius assembly为基础,分别设计并构建DNA元件标准化接口改造、单转录单元组装、应用质粒(多转录单元)组装等功能的载体,从而形成一套完整的多转录单元组装系统。【结果】构建了2个用于DNA元件标准化接口改造的Level 0载体,4个用于单转录单元组装的Level 1载体,4个用于应用质粒组装的Level 2载体和13个应用质粒组装的辅助质粒。然后应用此系统为齐整小核菌组装了若干经过标准化接口改造的DNA元件质粒、单转录单元质粒和硬葡聚糖相关基因的功能分析质粒。所构建的最终应用质粒可以同时适用于齐整小核菌的根癌农杆菌介导转化法、电穿孔转化法和原生质体转化法。【结论】此质粒系统具有强大的DNA设计、组装和容纳能力,为未来齐整小核菌代谢工程和功能基因组学研究提供了高效的质粒构建技术平台。 相似文献
225.
We have employed a structure-based design to construct a small folding domain from the F-actin bundling protein villin that contains the amino acids necessary for the DNA binding of the basic leucine zipper protein GCN4 and have compared its DNA binding with GCN4. The monomeric motif folds into a stable domain and binds DNA in a rigid-body mechanism, while its affinity is not higher than that of the basic region peptide. The addition of the leucine zipper region to the folded domain restored its sequence-specific DNA binding comparable to that of GCN4. Unlike the monomeric folded domain, its leucine zipper derivative undergoes a conformational change upon DNA binding. CD spectral and thermodynamic studies indicate that the DNA-contacting region is folded in the presence or absence of DNA and suggest that the junction between the DNA-contacting and the leucine zipper regions transits to a helix in the presence of DNA. These results demonstrate that the structural transition outside the direct-contacting region, which adjusts the precise location of the DNA-contacting region, plays a critical role in the specific complex formation of basic leucine zipper proteins. 相似文献
226.
Yasuo Yamazaki Hisashi Koike Yusuke Sugiyama Kazuko Motoyoshi Taeko Wada Shigeru Hishinuma Mitsuo Mita Takashi Morita 《European journal of biochemistry》2002,269(11):2708-2715
In this study, we isolated a 25-kDa novel snake venom protein, designated ablomin, from the venom of the Japanese Mamushi snake (Agkistrodon blomhoffi). The amino-acid sequence of this protein was determined by peptide sequencing and cDNA cloning. The deduced sequence showed high similarity to helothermine from the Mexican beaded lizard (Heloderma horridum horridum), which blocks voltage-gated calcium and potassium channels, and ryanodine receptors. Ablomin blocked contraction of rat tail arterial smooth muscle elicited by high K+-induced depolarization in the 0.1-1 microm range, but did not block caffeine-stimulated contraction. Furthermore, we isolated three other proteins from snake venoms that are homologous to ablomin and cloned the corresponding cDNAs. Two of these homologous proteins, triflin and latisemin, also inhibited high K+-induced contraction of the artery. These results indicate that several snake venoms contain novel proteins with neurotoxin-like activity. 相似文献
227.
Loss of infectivity by progeny virus from alpha interferon-treated human immunodeficiency virus type 1-infected T cells is associated with defective assembly of envelope gp120. 下载免费PDF全文
B D Hansen P L Nara R K Maheshwari G S Sidhu J G Bernbaum D Hoekzema M S Meltzer H E Gendelman 《Journal of virology》1992,66(12):7543-7548
228.
Sogawa K Numayama-Tsuruta K Takahashi T Matsushita N Miura C Nikawa J Gotoh O Kikuchi Y Fujii-Kuriyama Y 《Biochemical and biophysical research communications》2004,318(3):746-755
We have identified an enhancer responsible for induction by 3-methylcholanthrene in the upstream region of the CYP1A2 gene. The enhancer does not contain the invariant core sequence of XREs that are binding sites for the Ah receptor (AhR) and Arnt heterodimer. The enhancer did not show any inducible expression in Hepa-1-derived cell lines, C4 and C12, deficient of Arnt and AhR, respectively. On the other hand, bacterially expressed AhR-Arnt heterodimer could not bind to the enhancer. Mutational analysis of the enhancer revealed that a repeated sequence separated by six nucleotides is important for expression. A factor binding specifically to the enhancer was found by using gel shift assays. Bacterially expressed AhR-Arnt heterodimer interacted with the factor. A dominant negative mutant of the AhR to XRE activated the enhancer. Collectively, these results demonstrate that a novel induction mechanism is present in which the AhR-Arnt heterodimer functions as a coactivator. 相似文献
229.
A novel HLA-A*3303-restricted minor histocompatibility antigen encoded by an unconventional open reading frame of human TMSB4Y gene 总被引:4,自引:0,他引:4
Torikai H Akatsuka Y Miyazaki M Warren EH Oba T Tsujimura K Motoyoshi K Morishima Y Kodera Y Kuzushima K Takahashi T 《Journal of immunology (Baltimore, Md. : 1950)》2004,173(11):7046-7054
Female-to-male hemopoietic stem cell transplantation (HSCT) elicits T cell responses against male-specific minor histocompatibility (H-Y) Ags encoded by the Y chromosome. All previously identified H-Y Ags are encoded by conventional open reading frames, but we report in this study the identification of a novel H-Y Ag encoded in the 5'-untranslated region of the TMSB4Y gene. An HLA-A*3303-restricted CD8(+) CTL clone was isolated from a male patient after an HSCT from his HLA-identical sister. Using a panel of cell lines carrying Y chromosome terminal deletions, a narrow region controlling the susceptibility of these target cells to CTL recognition was localized. Minigene transfection and epitope reconstitution assays identified an 11-mer peptide, EVLLRPGLHFR, designated TMSB4Y/A33, whose first amino acid was located 405 bp upstream of the TMSB4Y initiation codon. Analysis of the precursor frequency of CTL specific for recipient minor histocompatibility Ags in post-HSCT peripheral blood T cells revealed that a significant fraction of the total donor CTL response in this patient was directed against the TMSB4Y epitope. Tetramer analysis continued to detect TMSB4Y/A33-specific CD8(+) T cells at least up to 700 days post-HSCT. This finding underscores the in vivo immunological relevance of minor histocompatibility Ags derived from unconventional open reading frame products. 相似文献
230.
Mikio Shimizu Ryo Okachi Kazuo Kimura Takashi Nara 《Bioscience, biotechnology, and biochemistry》2013,77(8):1655-1661
Penicillin acylase (EC 3.5.1.11) of Kluyvera citrophila KY7844 was purified approximately 120-fold by DEAE-cellulose chromatography, hydroxyapatite chromatography and isoelectro-focusing fractionation. The purified enzyme, with an approximate molecular weight of 63,000, appeared to be homogeneous in disc electrophoretic analysis, and showed isoelectric point (Ip) 8.12 and 13.0 units/mg of specific activity for cephalexin hydrolysis. The Michaelis constant (Km) for cephalexin and for 7-[1-(1H)-tetrazolylacetamido]-desacetoxycephalosporanic acid ((1H) T-7ADCA) was 1.4 mM and 3.6 mM, respectively. This enzyme was capable of producing (1H) T-7ADCA in 80% yield from 1-(1H)-tetrazolylacetate methylester and 7-aminodesacetoxycephalosporanic acid. 相似文献