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991.
992.
Sergey N. Borisov Ivan K. Iakovlev Alexey S. Borisov Andrey G. Zuev Alexei V. Tiunov 《Ecological Entomology》2020,45(6):1445-1456
- Sympetrum fonscolombii dragonflies are believed to migrate seasonally. In the spring and early summer, the already-mature dragonflies arrive in Middle Asia for reproduction. In the late summer and autumn, summer-generation dragonflies migrate to the south. Their wintering places remain unknown.
- Stable hydrogen (δ2H) and oxygen (δ18O) isotope analyses were conducted to confirm the migration of S. fonscolombii and determine the wintering area. Stable isotope composition of carbon (δ13C) and nitrogen (δ15N) in wings and legs was used to clarify the habitats in which dragonfly development took place.
- Three cohorts of dragonflies collected in different regions of Middle Asia were used for analysis: (i) immigrants that arrived in the spring, (ii) residents that developed in Middle Asia, and (iii) transit dragonflies migrating to the south during autumn.
- The average δ2H values in the wings were significantly higher in immigrants (−96‰) than in residents (−134‰) and transit individuals (−124‰). High δ18O and δ15N values in the tissue of immigrants confirmed their southerly origin.
- Based on the species range and the global distribution of annual averages of δ2H and δ18O values in precipitation, the latitudinal migrations of S. fonscolombii were inferred to cover the area from the proposed natal regions of immigrants in South-West Asia (below ∼36°N) to Southern Ural and the south of Western Siberia in the north (54–55°N) with a maximum migration distance of more than 4000 km.
993.
994.
Andrey Vorobiev 《BMJ (Clinical research ed.)》1992,305(6860):1022
995.
Lambert LJ Bobkov AA Smith JW Marassi FM 《The Journal of biological chemistry》2008,283(24):16665-16672
Integrin alpha2beta1 is a major receptor required for activation and adhesion of platelets, through the specific recognition of collagen by the alpha2-I domain (alpha2-I), which binds fibrillar collagen via Mg(2+)-bridged interactions. The crystal structure of a truncated form of the alpha2-I domain, bound to a triple helical collagen peptide, revealed conformational changes suggestive of a mechanism where the ligand-bound I domain can initiate and propagate conformational change to the full integrin complex. Collagen binding by alpha2-I and fibrinogen-dependent platelet activity can be inhibited by snake venom polypeptides. Here we describe the inhibitory effect of a short cyclic peptide derived from the snake toxin metalloprotease jararhagin, with specific amino acid sequence RKKH, on the ability of alpha2-I to bind triple helical collagen. Isothermal titration calorimetry measurements showed that the interactions of alpha2-I with collagen or RKKH peptide have similar affinities, and NMR chemical shift mapping experiments with (15)N-labeled alpha2-I, and unlabeled RKKH peptide, indicate that the peptide competes for the collagen-binding site of alpha2-I but does not induce a large scale conformational rearrangement of the I domain. 相似文献
996.
Flock U Thorndycroft FH Matorin AD Richardson DJ Watmough NJ Adelroth P 《The Journal of biological chemistry》2008,283(7):3839-3845
The bacterial respiratory nitric-oxide reductase (NOR) is a member of the superfamily of O(2)-reducing, proton-pumping, heme-copper oxidases. Even although nitric oxide reduction is a highly exergonic reaction, NOR is not a proton pump and rather than taking up protons from the cytoplasmic (membrane potential-negative) side of the membrane, like the heme-copper oxidases, NOR derives its substrate protons from the periplasmic (membrane potential-positive) side of the membrane. The molecular details of this non-electrogenic proton transfer are not yet resolved, so in this study we have explored a role in a proposed proton pathway for a conserved surface glutamate (Glu-122) in the catalytic subunit (NorB). The effect of substituting Glu-122 with Ala, Gln, or Asp on a single turnover of the reduced NOR variants with O(2), an alternative and experimentally tractable substrate for NOR, was determined. Electron transfer coupled to proton uptake to the bound O(2) is severely and specifically inhibited in both the E122A and E122Q variants, establishing the importance of a protonatable side chain at this position. In the E122D mutant, proton uptake is retained but it is associated with a significant increase in the observed pK(a) of the group donating protons to the active site. This suggests that Glu-122 is important in defining this proton donor. A second nearby glutamate (Glu-125) is also required for the electron transfer coupled to proton uptake, further emphasizing the importance of this region of NorB in proton transfer. Because Glu-122 is predicted to lie near the periplasmic surface of NOR, the results provide strong experimental evidence that this residue contributes to defining the aperture of a non-electrogenic "E-pathway" that serves to deliver protons from the periplasm to the buried active site in NOR. 相似文献
997.
Babenko AP 《The Journal of biological chemistry》2008,283(14):8778-8782
ATP/ADP-sensing (sulfonylurea receptor (SUR)/K(IR)6)(4) K(ATP) channels regulate the excitability of our insulin secreting and other vital cells via the differential MgATP/ADP-dependent stimulatory actions of their tissue-specific ATP-binding cassette regulatory subunits (sulfonylurea receptors), which counterbalance the nearly constant inhibitory action of ATP on the K(+) inwardly rectifying pore. Mutations in SUR1 that abolish its stimulation have been found in infants persistently releasing insulin. Activating mutations in SUR1 have been shown to cause neonatal diabetes. Here, analyses of K(IR)6.2-based channels with diabetogenic receptors reveal that MgATP-dependent hyper-stimulation of mutant SUR can compromise the ability of K(ATP) channels to function as metabolic sensors. I demonstrate that the channel hyperactivity rises exponentially with the number of hyperstimulating subunits, so small subpopulations of channels with more than two mutant SUR can dominate hyperpolarizing currents in heterozygous patients. I uncovered an attenuated tolbutamide inhibition of the hyperstimulated mutant, which is normally sensitive to the drug under non-stimulatory conditions. These findings show the key role of SUR in sensing the metabolic index in humans and urge others to (re)test mutant SUR/K(IR)6 channels from probands in physiologic MgATP. 相似文献
998.
Liu F Kovalevsky AY Tie Y Ghosh AK Harrison RW Weber IT 《Journal of molecular biology》2008,381(1):102-115
HIV-1 (human immunodeficiency virus type 1) protease (PR) and its mutants are important antiviral drug targets. The PR flap region is critical for binding substrates or inhibitors and catalytic activity. Hence, mutations of flap residues frequently contribute to reduced susceptibility to PR inhibitors in drug-resistant HIV. Structural and kinetic analyses were used to investigate the role of flap residues Gly48, Ile50, and Ile54 in the development of drug resistance. The crystal structures of flap mutants PRI50V (PR with I50V mutation), PRI54V (PR with I54V mutation), and PRI54M (PR with I54M mutation) complexed with saquinavir (SQV) as well as PRG48V (PR with G48V mutation), PRI54V, and PRI54M complexed with darunavir (DRV) were determined at resolutions of 1.05-1.40 Å. The PR mutants showed changes in flap conformation, interactions with adjacent residues, inhibitor binding, and the conformation of the 80s loop relative to the wild-type PR. The PR contacts with DRV were closer in PRG48V-DRV than in the wild-type PR-DRV, whereas they were longer in PRI54M-DRV. The relative inhibition of PRI54V and that of PRI54M were similar for SQV and DRV. PRG48V was about twofold less susceptible to SQV than to DRV, whereas the opposite was observed for PRI50V. The observed inhibition was in agreement with the association of G48V and I50V with clinical resistance to SQV and DRV, respectively. This analysis of structural and kinetic effects of the mutants will assist in the development of more effective inhibitors for drug-resistant HIV. 相似文献
999.
Irina G Moiseyeva Michael N Romanov Andrey A Nikiforov Antonina A Sevastyanova Serafima K Semyenova 《遗传、选种与进化》2003,35(5):403-423
Published results were reassessed and original data are provided regarding the origin and relatedness of four postulated chicken breed lineages, egg-type, game, meat-type and Bantam, to each other and to the basic ancestral species of jungle fowls, Gallus gallus. A system approach was employed concerning the planning of the experiments. One element of the system approach is the choice of the breeds to be compared with G. gallus. These breeds were supposed to represent major evolutionary branches of chickens. Four experiments on genetic relationships were conducted using different estimation criteria including morphological discrete characters, body measurements, biochemical markers, and the activity of serum esterase-1. The greatest similarity was found between G. gallus and the egg-type breeds of Mediterranean roots and/or true Bantams. This fact might testify that the indicated chicken groups occupied earlier stages in the evolution from the wild progenitor to the present biodiversity of chickens in the world. 相似文献
1000.
Hanna Julienne Vincent Laville Zachary R. McCaw Zihuai He Vincent Guillemot Carla Lasry Andrey Ziyatdinov Cyril Nerin Amaury Vaysse Pierre Lechat Herv Mnager Wilfried Le Goff Marie-Pierre Dube Peter Kraft Iuliana Ionita-Laza Bjarni J. Vilhjlmsson Hugues Aschard 《PLoS genetics》2021,17(8)
Genome-wide association studies (GWASs) have uncovered a wealth of associations between common variants and human phenotypes. Here, we present an integrative analysis of GWAS summary statistics from 36 phenotypes to decipher multitrait genetic architecture and its link with biological mechanisms. Our framework incorporates multitrait association mapping along with an investigation of the breakdown of genetic associations into clusters of variants harboring similar multitrait association profiles. Focusing on two subsets of immunity and metabolism phenotypes, we then demonstrate how genetic variants within clusters can be mapped to biological pathways and disease mechanisms. Finally, for the metabolism set, we investigate the link between gene cluster assignment and the success of drug targets in randomized controlled trials. 相似文献