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961.
Plants have large families of proteins sharing a conserved eight-cysteine-motif (8CM) domain. The biological functions of
these proteins are largely unknown. EARLI1 is a cold responsive Arabidopsis gene that encodes a hybrid proline-rich protein (HyPRP) with a three-domain architecture:
a putative signal peptide at the N-terminus, a proline-rich domain (PRD) in the middle, and an 8CM domain at the C-terminus.
We report here that yeast cells expressing different EARLI1 genes had significantly higher rates of freezing survival than empty-vector transformed controls. Arabidopsis plants with
knocked down EARLI1 genes had an increased tendency for freezing-induced cellular damage. EARLI1-GFP fluorescence in transgenic plants and immunoblot
analyses using protoplasts suggested cell wall localization for EARLI1 proteins. Immunoblot analyses showed that EARLI1 proteins
form higher order complexes in plants, and that the PRD is a soluble and the 8CM an insoluble protein domain. We propose that
EARLI1 proteins have a bimodular architecture in which the PRD may interact with the cell wall and the 8CM domain with the
plasma membrane to protect the cells during freezing stress. 相似文献
962.
Litterfall Production Along Successional and Altitudinal Gradients of Subtropical Monsoon Evergreen Broadleaved Forests in Guangdong, China 总被引:3,自引:0,他引:3
Guoyi Zhou Lili Guan Xiaohua Wei Deqiang Zhang Qianmei Zhang Junhua Yan Dazhi Wen Juxiu Liu Shuguang Liu Zhongliang Huang Guohui Kong Jiangming Mo Qingfa Yu 《Plant Ecology》2007,188(1):77-89
Evaluation of litterfall production is important for understanding nutrient cycling, forest growth, successional pathways, and interactions with environmental variables in forest ecosystems. Litterfall was intensively studied during the period of 1982–2001 in two subtropical monsoon vegetation gradients in the Dinghushan Biosphere Reserve, Guangdong Province, China. The two gradients include: (1) a successional gradient composed of pine forest (PF), mixed pine and broadleaved forest (MF) and monsoon evergreen broadleaved forest (BF), and (2) an altitudinal gradient composed of Baiyunci ravine rain forest (BRF), Qingyunci ravine rain forest (QRF), BF and mountainous evergreen broadleaved forest (MMF). Mean annual litterfall production was 356, 861 and 849 g m−2 for PF, MF and BF of the successional gradient, and 1016, 1061, 849 and 489 g m−2 for BRF, QRF, BF and MMF of the altitudinal gradient, respectively. As expected, mean annual litterfall of the pioneer forest PF was the lowest, but rapidly increased over the observation period while those in other forests were relatively stable, confirming that forest litterfall production is closely related to successional stages and growth patterns. Leaf proportions of total litterfall in PF, MF, BF, BRF, QRF and MMF were 76.4%, 68.4%, 56.8%, 55.7%, 57.6% and 69.2%, respectively, which were consistent with the results from studies in other evergreen broadleaved forests. Our analysis on litterfall monthly distributions indicated that litterfall production was much higher during the period of April to September compared to other months for all studied forest types. Although there were significant impacts of some climate variables (maximum and effective temperatures) on litterfall production in some of the studied forests, the mechanisms of how climate factors (temperature and rainfall) interactively affect litterfall await further study. 相似文献
963.
Jin Wang Kai-Jing Zuo Jie Qin Lida Zhang Lan Su Junrong Liu Hua Ling Jing-Ya Zhao You-Fang Cao Ke-Xuan Tang 《Acta Physiologiae Plantarum》2007,29(1):1-9
A novel cDNA clone encoding a COR413-like gene was isolated by suppression subtraction hybridization and cDNA library screening from sea-island cotton (Gossypium barbadense). This gene (designated as GbCOR413, Accession number: AY761065) has a total length of 893 bp with an open reading frame of 600 bp, encoding a predicated polypeptide
of 200 amino acids with a molecular weight of 22.74 kDa and a predicated pI of 9.2. Bioinformatics analyses revealed that this gene belonged to a novel stress-regulated multi-spanning transmembrane
protein family without signal peptide. By means of semi-quantities RT-PCR analysis, the expression of GbCOR413 under short-term cold treatment at 4°C, water submergence and abscic acid treatment was investigated. Our studies suggested
that the cloned gene was a new member of COR gene family which was slowly responsive to cold stress in cotton.
Jin Wang and Kai-Jing Zuo are co-first authors of this paper. 相似文献
964.
目的探讨进展期胃癌生长过程中p53基因表达与微血管密度和生物学行为之间的关系。方法搜集有随访资料的胃癌标本107例,用免疫组化对突变型p53和CD34作了标记,用原位杂交对野生型p53作了检测。结果突变型p53在肿瘤不同侵犯深度、不同生长方式、不同淋巴结转移状态以及预后方面,存在显著差异(P<0.05),突变型p53与微血管密度显著相关(P<0.05),而野生型p53则与突变型p53相反。结论突变型和野生型p53在肿瘤生长过程中的表达不同,说明p53的不同功能状态在肿瘤的发展过程中发挥重要作用。 相似文献
965.
Acetyl-CoA carboxylase (ACCase) (EC.6.4.1.2) is an essential enzyme in fatty acid biosynthesis and, in world agriculture,
commercial herbicides target this enzyme in plant species. In nearly all grass species the plastidic ACCase is strongly inhibited
by commercial ACCase inhibiting herbicides [aryloxyphenoxypropionate (APP) and cyclohexanedione (CHD) herbicide chemicals].
Many ACCase herbicide resistant biotypes (populations) of L. rigidum have evolved, especially in Australia. In many cases, resistance to ACCase inhibiting herbicides is due to a resistant ACCase
enzyme. Two ACCase herbicide resistant L. rigidum biotypes were studied to identify the molecular basis of ACCase inhibiting herbicide resistance. The carboxyl-transferase
(CT) domain of the plastidic ACCase gene was amplified by PCR and sequenced. Amino acid substitutions in the CT domain were
identified by comparison of sequences from resistant and susceptible plants. The amino acid residues Gln-102 (CAG codon) and
Ile-127 (ATA codon) were substituted with a Glu residue (GAG codon) and Leu residue (TTA codon), respectively, in both resistant
biotypes. Amino acid positions 102 and 127 within the fragment sequenced from L. rigidum corresponded to amino acid residues 1756 and 1781, respectively, in the A. myosuroides full ACCase sequence. Allele-specific PCR results further confirmed the mutations linked with resistance in these populations.
The Ile-to-Leu substitution at position 1781 has been identified in other resistant grass species as endowing resistance to
APP and CHD herbicides. The Gln-to-Glu substitution at position 1756 has not previously been reported and its role in herbicide
resistance remains to be established. 相似文献
966.
Ya. E. Dunaevsky Dong Zhang A. R. Matveeva G. A. Belyakova M. A. Belozersky 《Microbiology》2006,75(1):35-39
The ability of various xylotrophs to produce extracellular proteolytic enzymes has been studied, with emphasis on medium-related factors regulating their secretion. Direct measurement of proteolytic activity in the culture liquid and postelectrophoresis determination of protease activity in polyacrylamide gel copolymerized with gelatin demonstrated that the secreted enzymes are quantitatively and qualitatively diverse. Activity levels of extracellular proteolytic enzymes strongly depend on pH and contents of protein and carbohydrate in the medium. All secreted proteases notably differed in molecular weight (of 51 kDa or higher and in excess of 95 kDa) and belonged mostly to two classes of proteolytic enzymes (serine proteases and metalloproteinases). 相似文献
967.
968.
The lack of a rigorous analytical theory for DNA looping has caused many DNA-loop-mediated phenomena to be interpreted using theories describing the related process of DNA cyclization. However, distinctions in the mechanics of DNA looping versus cyclization can have profound quantitative effects on the thermodynamics of loop closure. We have extended a statistical mechanical theory recently developed for DNA cyclization to model DNA looping, taking into account protein flexibility. Notwithstanding the underlying theoretical similarity, we find that the topological constraint of loop closure leads to the coexistence of multiple classes of loops mediated by the same protein structure. These loop topologies are characterized by dramatic differences in twist and writhe; because of the strong coupling of twist and writhe within a loop, DNA looping can exhibit a complex overall helical dependence in terms of amplitude, phase, and deviations from uniform helical periodicity. Moreover, the DNA-length dependence of optimal looping efficiency depends on protein elasticity, protein geometry, and the presence of intrinsic DNA bends. We derive a rigorous theory of loop formation that connects global mechanical and geometric properties of both DNA and protein and demonstrates the importance of protein flexibility in loop-mediated protein-DNA interactions. 相似文献
969.
The receptor for human endothelial differentiation gene-1 protein (EDG-1) was C-terminally tagged with green fluorescent protein and expressed in the methylotrophic yeast, Pichia pastoris. EDG-1 expression was driven by the highly inducible alcohol oxidase 1 promoter. Expression of EDG-1 recombinant protein was detected by Western blot analysis and confocal microscopy. The recombinant EDG-1 receptor protein was located in the plasma membrane. Radioligand binding assays demonstrated that the␣EDG-1 receptors expressed in Pichia pastoris␣have specific and saturation binding of 32P-labeled sphingosine 1-phosphate. 相似文献
970.
The genetic diversity among indigenous phenazine-1-carboxylic acid (PCA)-producing and pyoluteorin (Plt)-producing isolates
of pseudomonads screened from green pepper rhizosphere was exploited in this study. A total of 48 bacterium isolates producing
one or both of these antibiotics were screened from green pepper rhizosphere in diverse regions in China. Among these isolates,
45 could produce PCA, 3 could produce both PCA and Plt, and none could produce Plt only. Based on the restriction patterns
of partial 16S and 16S-23S internal transcribed spacer (ITS) PCR fragments generated by enzyme HaeIII or HinfI, these isolates fell into 19 or 17 distinct groups respectively, indicating that there was a significant diversity among
them. Polygenetic analysis of the partial 16S rDNA and 16S-23S ITS sequence from the representative in each group in the context
of similar sequence from previously described bacterial species indicated that most isolates were closely related to the species
of Pseudomonas fluorescens, P. putida, and Stenotrophomonas maltophilia. Some of these representatives of these isolates, then, are likely to be novel strains or species in these two genera.
The GenBank accession numbers for DNA sequences of the partial 16S rDNA with ITS region in each isolate determined in this
study were: GP30 DQ003219; GP127 DQ003220; GP83 DQ003221; GP42, DQ003222; GP59 DQ003223; GP50 DQ003224; GP36 DQ003225; GP110
DQ003226; GP26 DQ003227; GP37 DQ003228; GP60 DQ003229; GP31 DQ003230; GP57 DQ003231; GP75 DQ003232; GP115 DQ003233; GP65 DQ003234;
GP32 DQ003235; GP76 DQ003236; GP78 DQ003237. 相似文献