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1.
Abstract A mutant strain of Schizosaccharomyces pombe lacking dipeptidyl aminopeptidase yspI was isolated from a strain already defective in aminopeptidase activity by means of a staining technique with the chromogenic substrate ala-pro-4-methoxy-β-naphthylamide to screen colonies for the absence of the enzyme. The defect segregated 2+ :2− in meiotic tetrads, indicating a single chromosomal gene mutation, which was shown to be recessive. Gene dosage experiments indicated that the mutation resides in the structural gene of dipeptidyl aminopeptidase yspI, dpa 1+ . The dpa 1+ gene was located on chromosome III by using l m- fluorophen-ylalanine-induced haploidization and mitotic analysis. dpa1 mutants did not show any obvious phenotype under a variety of conditions tested. 相似文献
2.
Francisco Gutirrez‐Corchero M. Victoria Arruga Lourdes Sanz Cristina García M. Angeles Hernndez Francisco Campos 《Molecular ecology resources》2002,2(1):75-77
FTA® cards were used for long‐term storage of avian blood samples. Blood DNA was extracted by a simple method and used in PCR for sex identification of adult and nestling Great Grey Shrikes Lanius excubitor. 相似文献
3.
Leonardo Antnio Fernandes Anderson Albino Gomes Beatriz Gomes Guimares Maria de Lourdes Borba Magalhes Partha Ray Gustavo Felippe da Silva 《Protein science : a publication of the Protein Society》2022,31(6)
The binding of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) spike protein to the angiotensin‐converting enzyme 2 (ACE2) receptor expressed on the host cells is a critical initial step for viral infection. This interaction is blocked through competitive inhibition by soluble ACE2 protein. Therefore, developing high‐affinity and cost‐effective ACE2 mimetic ligands that disrupt this protein–protein interaction is a promising strategy for viral diagnostics and therapy. We employed human and plant defensins, a class of small (2–5 kDa) and highly stable proteins containing solvent‐exposed alpha‐helix, conformationally constrained by two disulfide bonds. Therefore, we engineered the amino acid residues on the constrained alpha‐helix of defensins to mimic the critical residues on the ACE2 helix 1 that interact with the SARS‐CoV‐2 spike protein. The engineered proteins (h‐deface2, p‐deface2, and p‐deface2‐MUT) were soluble and purified to homogeneity with a high yield from a bacterial expression system. The proteins demonstrated exceptional thermostability (Tm 70.7°C), high‐affinity binding to the spike protein with apparent K d values of 54.4 ± 11.3, 33.5 ± 8.2, and 14.4 ± 3.5 nM for h‐deface2, p‐deface2, and p‐deface2‐MUT, respectively, and were used in a diagnostic assay that detected SARS‐CoV‐2 neutralizing antibodies. This work addresses the challenge of developing helical ACE2 mimetics by demonstrating that defensins provide promising scaffolds to engineer alpha‐helices in a constrained form for designing of high‐affinity ligands. 相似文献
4.
5.
Seasonal changes in condition, nutrition, gonad maturation and energy content in barbel, Barbus sclateri, inhabiting a fluctuating river 总被引:2,自引:0,他引:2
The objective of this study was to investigate the seasonal cycle of condition, nutrition and gonad development, as well as
the magnitude of seasonal variations in energy content of somatic and gonad tissues in juveniles, males and females of Sclater's
barbel, Barbus sclateri, from the upper Guadalete River (south Spain). The influence of reproductive cycle on somatic changes
was also investigated and discussed. Measurements of condition factor (K), somatic index (SI), gonadosomatic index (GSI) and
somatic and gonad energy content (J g-1 dw) were made in individual specimens taken from the Guadalete River monthly for 12 months. This freshwater ecosystem is
characterised by strong seasonal fluctuations in water and flow level, temperature and food supply. It was found that in general
juveniles, males and females of barbel exhibited a similar condition, nutrition and somatic energy cycle throughout the year,
with the highest values in spring and the lowest in summer. Depletion of K, SI and somatic energy storage from spring until
mid-summer seems to be associated with high metabolic demands during this period, and in adult fish also with spawning-related
activity. The gonad index and energy content of the gonad were the highest in April and the lowest in summer for both sexes.
Spawning took place during late spring – early summer, with fish quiescent by mid summer. The energy required for ovarian
development (3970 J g-1 dw) was greater than the one for testes development (2763 J g-1 dw). Data on gonad energy content indicated a period (March to April) of intense energy accumulation (64% males and 37% females)
which was related to the decline in the average somatic energy content in males and females. The somatic energy content was
linearly related to K and SI. In the same way, GSI correlated positively with gonad energy. Linear trends were found between
somatic parameters (K, SI and energy content) and gonad parameters (GSI and energy content).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
Elizabeth H. M. Tyler Paul J. Somerfield Edward Vanden Berghe Julie Bremner Emma Jackson Olivia Langmead Maria Lourdes D. Palomares Thomas J. Webb 《Global Ecology and Biogeography》2012,21(9):922-934
Aim Ecologists seeking to describe patterns at ever larger scales require compilations of data on the global abundance and distribution of species. Comparable compilations of biological data are needed to elucidate the mechanisms behind these patterns, but have received far less attention. We assess the availability of biological data across an entire assemblage: the well‐documented demersal marine fauna of the United Kingdom. We also test whether data availability for a species depends on its taxonomic group, maximum body size, the number of times it has been recorded in a global biogeographic database, or its commercial and conservation importance. Location Seas of the United Kingdom. Methods We defined a demersal marine fauna of 973 species from 15 phyla and 40 classes using five extensive surveys around the British Isles. We then quantified the availability of data on eight key biological traits (termed biological knowledge) for each species from online databases. Relationships between biological knowledge and our predictors were tested with generalized linear models. Results Full data on eight fundamental biological traits exist for only 9% (n= 88) of the UK demersal marine fauna, and 20% of species completely lack data. Clear trends in our knowledge exist: fish (median biological knowledge score = six traits) are much better known than invertebrates (one trait). Biological knowledge increases with biogeographic knowledge and (to a lesser extent) with body size, and is greater in species that are commercially exploited or of conservation concern. Main conclusions Our analysis reveals deep ignorance of the basic biology of a well‐studied fauna, highlighting the need for far greater efforts to compile biological trait data. Clear biases in our knowledge, relating to how well sampled or ‘important’ species are suggests that caution is required in extrapolating small subsets of biologically well‐known species to ecosystem‐level studies. 相似文献
7.
José Antonio López-Sáez Lourdes López-Merino Francisca Alba-Sánchez Sebastián Pérez-Díaz Daniel Abel-Schaad José S. Carrión 《Plant Ecology》2010,206(2):195-209
This article describes the patterns and processes of vegetation change and fire history in the Late Holocene (c. 2400 calendar year
BP) palaeoecological sequence of Lanzahíta, Sierra de Gredos in central Spain, and provides the first Iberian pollen sequence
undertaken within a monospecific Pinus pinaster woodland. These new data reassess not only the autochthonous nature of this pine species in the region and the Iberian Peninsula,
but also the naturalness of well-developed cluster pine forests. Conflicts of palaeoecological evidence with phytosociological
models of vegetation dynamics in the study region, and the relationships of P. pinaster with fire occurrence in Mediterranean-type ecosystems, are discussed. 相似文献
8.
Light modulation and in vitro effects of adenine nucleotides on leaf nitrate reductase activity in cucumber (Cucumis sativus) 总被引:1,自引:0,他引:1
Eloísa Agüera Lourdes Poblete Purificación de la Haba José M. Maldonado 《Physiologia plantarum》1999,105(2):218-223
Nitrate reductase (NR, EC 1.6.6.1) activity in attached cucumber ( Cucumis sativus L. cv. Ashley) leaves changed rapidly and reversibly during light/dark transitions, especially when assayed in the presence of free Mg2+ . Light decreased and darkness increased the sensitivity of the enzyme to inhibition by Mg2+ . The NR activation state, i.e. activity in the presence of Mg2+ relative to activity in the absence of Mg2+ , increased with light intensity up to 400 μmol m−2 s−1 PAR (photosynthetically active radiation). When a desalted crude extract from illuminated leaves was preincubated with ATP, NR was gradually inactivated. Inactivation was only observed when activity was assayed in the presence of Mg2+ . The ATP-inactivated NR remained inactive after removing the excess of ATP by gel filtration and it did not occur in partially purified NR preparations. NR extracted from darkened attached leaves was markedly activated when preincubated with 5'-AMP. These results support the view that inactivation/activation of cucumber-leaf NR in response to light/dark signals most likely involves phosphorylation/dephosphorylation of the enzyme catalysed by endogenous proteins. A substantial activation of NR by preincubation with 5'-AMP was also observed when activity was assayed in the absence of Mg2+ , thus indicating that 5'-AMP can directly activate NR. Irradiation of an extract from darkened leaves containing FAD promoted a partial activation of NR. This effect was observed both in the +Mg2+ and in the −Mg2+ assay, indicating that activation was caused by photoexcited flavin and did not involve dephosphorylation of the enzyme. 相似文献
9.
Lourdes J. Cruz William R. Gray Baldomero M. Olivera 《Archives of biochemistry and biophysics》1978,190(2):539-548
Previous studies (R. Endean et al. (1974), Toxicon12: 131–138) indicate that whole venom from the marine mollusc Conus geographus directly inhibits skeletal muscle, leaving peripheral nerves, cardiac and smooth muscle unaffected. A quantitative bioassay has been used to detect and measure biologically active myotoxin. By using chromatography on phosphocellulose, purified myotoxin is obtained which has the same physiological effects as whole venom. The LD50 of purified toxin is 12 μg/kg in mice, death occurring as a result of flaccid paralysis and respiratory failure. A biochemical characterization of the purified myotoxin indicates that it is a peptide of 13 amino acids containing two disulfide bonds. This and related peptide myotoxins from Conus should be of exceptional interest in muscle physiology. 相似文献
10.
Lourdes Velo-Suárez Michael L. Brosnahan Donald M. Anderson Dennis J. McGillicuddy Jr. 《PloS one》2013,8(12)
Parasitic dinoflagellates of the genus Amoebophrya infect free-living dinoflagellates, some of which can cause harmful algal blooms (HABs). High prevalence of Amoebophrya spp. has been linked to the decline of some HABs in marine systems. The objective of this study was to evaluate the impact of Amoebophrya spp. on the dynamics of dinoflagellate blooms in Salt Pond (MA, USA), particularly the harmful species Alexandrium fundyense. The abundance of Amoebophrya life stages was estimated 3–7 days per week through the full duration of an annual A. fundyense bloom using fluorescence in situ hybridization coupled with tyramide signal amplification (FISH- TSA). More than 20 potential hosts were recorded including Dinophysis spp., Protoperidinium spp. and Gonyaulax spp., but the only dinoflagellate cells infected by Amoebophrya spp. during the sampling period were A. fundyense. Maximum A. fundyense concentration co-occurred with an increase of infected hosts, followed by a massive release of Amoebophrya dinospores in the water column. On average, Amoebophrya spp. infected and killed ∼30% of the A. fundyense population per day in the end phase of the bloom. The decline of the host A. fundyense population coincided with a dramatic life-cycle transition from vegetative division to sexual fusion. This transition occurred after maximum infected host concentrations and before peak infection percentages were observed, suggesting that most A. fundyense escaped parasite infection through sexual fusion. The results of this work highlight the importance of high frequency sampling of both parasite and host populations to accurately assess the impact of parasites on natural plankton assemblages. 相似文献