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941.
942.
Biological Trace Element Research - Over the past years, adipose tissue has become an invaluable source of mesenchymal stem cells (MSCs) due to development of improved isolation methodologies. In a...  相似文献   
943.
The behaviour of locusts has been studied extensively using two approaches: (1) analysing a single individual's response to a group stimulus or (2) using group conditions to look at aggregation patterns. The second approach has, in contrast with the first one, not been improved in terms of statistical analyses since the 1960s. In the present study, we propose a spatial statistics approach of point‐pattern analysis to improve the group‐based assessment of behavioural phase characterization. This diagnostic tool was developed and tested in the laboratory with comparative analysis of solitarious (isolation‐reared) and gregarious (crowd‐reared) desert locusts, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae). The spatial distribution patterns of 10 either solitarious or gregarious third‐instar hoppers were characterized with nearest neighbour distance measurements in a circular arena. The temporal sequence of spatial disposition of locusts was recorded with a digital camera taking photographs at regular intervals. The approach of point‐pattern analysis focused on the spatial distribution of observed events and allowed us to make inferences about the underlying process that generated them. The results confirmed that our diagnostic tool could identify that crowd‐reared hoppers tended to aggregate more to conspecifics than isolation‐reared ones. We could also verify that isolation‐reared hoppers were less active than crowd‐reared ones, but this was only true at the beginning of the experiments. The spatial statistics approach proposed in the present study could help with observations of phase‐related differences in the behaviour of locusts.  相似文献   
944.
Non-synonymous single nucleotide polymorphisms (nsSNPs) represent common genomic variations that alter protein sequence and function. Some nsSNPs affecting conserved amino acids have been reported to be associated with cancer susceptibility. Interestingly, Epidermal Growth Factor Receptor (EGFR) is commonly overexpressed and mutated in many cancers. In this study, we investigated the structural effect of three deleterious nsSNPs: rs17337451 (R962G), rs1140476 (R977C) and rs17290699 (H988P) within EGFR using computational tools. The modelled mutant dimers showed less stability than wild type EGFR dimer. Furthermore, we showed the important role of R962 and H988 residues in the EGFR dimer formation. We also report preliminary experimental data for SNP R977C suggesting that the variant C977 might confer greater risk for breast cancer. These results contribute to an improved understanding of the EGFR dimer stability and provide new elements for understanding the relationship between EGFR and cancer.  相似文献   
945.
946.
Gliadin polymorphism in 19 landrace populations of Turkish cultivated emmer wheat [Triticum turgidum L. ssp. dicoccon (Schrank) Thell.] was assessed using the aluminum lactic acid-polyacrylamide gel electrophoresis (A-PAGE) technique. Being a source of useful genes, landraces of wheat represent one of the most important genetic resources available to breeders for present and future genetic improvement of wheat. This is the first genetic characterization of these 19 Turkish emmer wheat landrace populations collected from their main cultivation areas. Considerably high amounts of variation were detected within and among the populations. A total of 27 alleles (n a) were identified among all analyzed populations, 10 of them being unique to populations?C, D, H, K, L, M, and N. The highest allele number (n a?=?7) was observed in populations?A and L, whereas the lowest number of alleles (n a?=?3) was observed in populations?F, G, and U. The mean number of effective alleles (n ae) was 12.33, and the mean values of gene diversity, genetic differentiation, and gene flow between populations were H e?=?0.92, F ST?=?0.296, and N m ?=?0.60, respectively. Certain gliadins closely linked to dough quality, such as ??-45 and ??-35, were found in 13 and 18 of the populations, respectively. According to Pearson??s correlation coefficient values, gene diversity estimates had strong positive correlation (r P?=?0.510; p?=?0.026 at <0.05%) with latitude. The rest of the genetic data (n a and n ae) obtained in the present study showed no correlation with geographic (altitude, latitude, and longitude) or climatic factors (temperature and annual rainfall). Principal component analysis was performed to explain spatial genetic variation, revealing 90.044% of total genetic variation in three components. Results obtained from this study can effectively be used in developing more efficient breeding programs to improve wheat genotypes, and to direct genetic resource conservation studies.  相似文献   
947.
易祖志广  黄文珊 《蛇志》1997,9(3):60-62
55岁以下中青年肺心病90例与同期收治的60岁以上老年肺心病90例作对照,发现中青年组有如下特点:①原发疾病两组均以慢性支气管炎多见,但中青年组肺结核、支气管扩张常见,合并高血压、冠心病少见。②主要症状、体征以咯血、杵状指、体温大于37℃多见,神志改变、早搏较老年组少见。③白细胞总数增高、痰培养G+球菌多见。G-杆菌少见。④血气分析低氧血症多见。⑤心电图以右室肥厚多见,与X线右室肥厚多相一致。⑥多脏器衰竭(MSOF)为主要死因  相似文献   
948.
The chemical composition of the Tamarix boveana volatile oils obtained from the whole aerial part, flowers, leaves and stems by steam distillation was analysed using gas chromatograph (GC)-flame ionization detectors (FID) and GC-MS. Sixty-two components were identified. Hexadecanoic acid (18.14%), docosane (13.34%), germacrene D (7.68%), fenchyl acetate (7.34%), Benzyl benzoate (4.11%) were found to be the major components in the whole aerial parts. This composition differed according to the tested part: 2.4 Nonadienal was the main compound in the flowers (12.13%) while germacrene D was the major component in leaves (31.43%) and hexadecanoic acid in the stems (13.94%). To evaluate in vitro antimicrobial activity, all volatile oils were tested against six Gram-positive and Gram-negative bacteria and four fungi. The T. boveana volatile oils exhibited an interesting antibacterial activity against all strains tested except Pseudomonas aeruginosa but no antifungal activity was detected.  相似文献   
949.
Using the MP1-p14 scaffolding complex from the mitogen-activated protein kinase signaling pathway as model system, we explored a structure-based computational protocol to probe and characterize binding affinity hot spots at protein-protein interfaces. Hot spots are located by virtual alanine-scanning consensus predictions over three different energy functions and two different single-structure representations of the complex. Refined binding affinity predictions for select hot-spot mutations are carried out by applying first-principle methods such as the molecular mechanics generalized Born surface area (MM-GBSA) and solvated interaction energy (SIE) to the molecular dynamics (MD) trajectories for mutated and wild-type complexes. Here, predicted hot-spot residues were actually mutated to alanine, and crystal structures of the mutated complexes were determined. Two mutated MP1-p14 complexes were investigated, the p14(Y56A)-mutated complex and the MP1(L63A,L65A)-mutated complex. Alternative ways to generate MD ensembles for mutant complexes, not relying on crystal structures for mutated complexes, were also investigated. The SIE function, fitted on protein-ligand binding affinities, gave absolute binding affinity predictions in excellent agreement with experiment and outperformed standard MM-GBSA predictions when tested on the MD ensembles of Ras-Raf and Ras-RalGDS protein-protein complexes. For wild-type and mutant MP1-p14 complexes, SIE predictions of relative binding affinities were supported by a yeast two-hybrid assay that provided semiquantitative relative interaction strengths. Results on the MP1-mutated complex suggested that SIE predictions deteriorate if mutant MD ensembles are approximated by just mutating the wild-type MD trajectory. The SIE data on the p14-mutated complex indicated feasibility for generating mutant MD ensembles from mutated wild-type crystal structure, despite local structural differences observed upon mutation. For energetic considerations, this would circumvent costly needs to produce and crystallize mutated complexes. The sensitized protein-protein interface afforded by the p14(Y56A) mutation identified here has practical applications in screening-based discovery of first-generation small-molecule hits for further development into specific modulators of the mitogen-activated protein kinase signaling pathway.  相似文献   
950.
Gaucher disease, the most prevalent lysosomal storage disorder, is principally caused by malfunction of the lysosomal enzyme glucocerebrosidase (GBA), a 497-amino acid membrane glycoprotein that catalyzes the hydrolysis of glucosylceramide to ceramide and glucose in the presence of an essential 84-residue activator peptide named saposin C (SapC). Knowledge of the GBA structure, a typical (beta/alpha)(8) TIM barrel, explains the effect of few mutations, directly affecting or located near the catalytic site. To identify new regions crucial for proper GBA functionality, we analyzed the interactions of the enzyme with a second (substrate) and a third (cofactor) partner. We build 3D docking models of the GBA-SapC and the GBA-ceramide interactions, by means of methodologies that integrate both evolutive and structural information. The GBA-SapC docking model confirm the implication of three spatially closed regions of the GBA surface (TIM barrel-helix 6 and helix 7, and the Ig-like domain) in binding the SapC molecule. This model provides new basis to understand the pathogenicity of several mutations, such as the prevalent Leu444Pro, and the additive effect of Glu326Lys in the double mutant Glu326Lys-Leu444Pro. Overall, 39 positions in which amino acid changes are known to cause Gaucher disease were localized in the GBA regions identified in this work. Our model is discussed in relation to the phenotype (pathogenic effect) of these mutations, as well as to the enzymatic activity of the recombinant proteins when available. Both data fully correlates with the proposed model, which will provide a new tool to better understand Gaucher disease and to design new therapy strategies.  相似文献   
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