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1.
Maria João Feio Trefor B. Reynoldson Verónica Ferreira Manuel Augusto S. Graça 《Hydrobiologia》2007,579(1):55-68
We sampled macroinvertebrates at 75 locations in the Mondego river catchment, Central Portugal, and developed a predictive
model for water quality assessment of this basin, based on the Reference Condition Approach. Sampling was done from June to
September 2001. Fifty-five sites were identified as “Reference sites” and 20 sites were used as “Test sites” to test the model.
At each site we also measured 40 habitat variables to characterize water physics and chemistry, habitat type, land use, stream
hydrology and geographic location. Macroinvertebrates were generally identified to species or genus level; a total of 207
taxa were found. By Unweighted Pair Group Method with Arithmetic mean (UPGMA) clustering and analysis of species contribution
to similarities percentage (SIMPER), two groups of reference sites were established. Using Discriminant Analysis (stepwise
forward), four variables correctly predicted 78% of the reference sites to the appropriate group: stream order, pool quality,
substrate quality and current velocity. Test sites’ environmental quality was established from their relative distance to
reference sites, in MDS ordination space, using a series of bands (BEAST methodology). The model performed well at upstream
sites, but at downstream sites it was compromised by the lack of reference sites. As with the English RIVPACS predictive model,
the Mondego model should be continually improved with the addition of new reference sites. The adaptation of the Mondego model
methodology to the Water Framework Directive is possible and would consist mainly of the integration of the WFD typology and
increasing the number of ellipses that define quality bands.
Handling editor: K. Martens 相似文献
2.
Fine root distribution of trees and understory in mature stands of maritime pine (Pinus pinaster) on dry and humid sites 总被引:2,自引:0,他引:2
Maritime pine (Pinus pinaster) is the main tree cropping species in the Landes of Gascogne forest range in south western France. Soils are nutrient poor, sandy podzosols and site fertility is determined essentially by organic matter content and depth of water table, which is known to limit root growth. We hypothesised, with an ultimate goal of constructing a nutrient uptake model applicable to this region, that the organic top horizons together with the depth of the water table should be the most important parameters related to fine root distribution and presence of associated mycorrhiza. To test this hypothesis, we compared two adult Pinus pinaster stands, contrasting in depth of water table and soil fertility and evaluated fine roots (diameter ≤2 mm) of understory species and fine roots and ectomycorrhizal morphotypes of Pinus pinaster down to 1.2 m, using a soil corer approach. Total fine root biomass of Pinus pinaster was not significantly different between both sites (3.6 and 4.5 t ha−1 for the humid, respectively, dry site), but root distribution was significantly shallower and root diameter increased more with depth at the humid site, presumably due to more adverse soil conditions as related to the presence of a hardpan, higher amount of aluminium oxides and / or anoxia. Fine roots of Pinus pinaster represented only about 30% of total fine root biomass and 15% of total fine root length, suggesting that the understory species cannot be ignored with regards to competition for mineral nutrients and water. A comparison of the ectomycorrhizal morphotypes showed that the humid site could be characterised by a very large proportion of contact exploration types, thought to be more relevant in accessing organic nutrient sources, whereas the dry site had a significantly higher proportion of both long-distance and short-distance exploration types, the latter of which was thought to be more resistant to short-term drought periods. These results partly confirm our hypothesis on root distribution as related to the presence of soil mineral nutrients (i.e. in organic matter), point out the potential role of understory plant species and ectomycorrhizal symbiosis and are a valuable step in building a site-specific nutrient uptake model. 相似文献
3.
Augusto Pessina 《Cytotechnology》1993,12(1-3):127-135
4.
O Augusto C L Weingrill S Schreier H Amemiya 《Archives of biochemistry and biophysics》1986,244(1):147-155
Kinetic, circular dichroism, and NADH and NADPH fluorescence quenching studies indicate that these compounds interact with the antimalarial drug primaquine (PQ). The affinity of both pyridine nucleotides for PQ is similar. The data are in contrast with a previous report (Thornalley et al. (1983) Biochem. Pharmacol. 32, 3571-3575) suggesting specificity for the interaction with NADPH. The complex was seen to facilitate electron transfer from NAD(P)H to oxygen, generating oxygen-free radicals which were detected by the spin-trapping technique and to flavin nucleotides, giving rise to flavin semiquinone radicals which were demonstrated by direct ESR spectroscopy under anaerobic conditions. A twofold increase in oxygen uptake and hydroxyl radical generation by the NAD(P)H-PQ complex was observed in the presence of hemoglobin. This effect was independent of heme concentration (in the range 1 X 10(-5)-1 X 10(-4) M) and oxidation state of the iron. Under anaerobic conditions, the NAD(P)H-PQ complex reduces Fe-III to Fe-II hemoglobin, and under aerobic conditions about 65% of the heme chromophore is irreversibly destroyed. Superoxide dismutase inhibits hydroxyl radical generation by the NAD(P)H-PQ pair; this effect is not observed in the presence of hemoglobin. In the presence of microsomes there is a 10-fold increase in both oxygen consumption and hydroxyl radical generation by the NAD(P)H-PQ pair. The fact that both pyridine nucleotides are active, and the inability of SKF 525A in decreasing hydroxyl radical generation, suggests that microsomal reductases are involved in the catalysis. 相似文献
5.
Flow through a Collapsible Tube: Experimental Analysis and Mathematical Model 总被引:2,自引:0,他引:2 下载免费PDF全文
Flow through thin-wall axisymmetric tubes has long been of interest to physiologists. Analysis is complicated by the fact that such tubes will collapse when the transmural pressure (internal minus external pressure) is near zero. Because of the absence of any body of related knowledge in other sciences or engineering, previous workers have directed their efforts towards experimental studies of flow in collapsible tubes. More recently, some attention has been given towards analytical studies. Results of an extensive series of experiments show that the significant system parameter is transmural pressure. The cross-sectional area of the tube depends upon the transmural pressure, and changes in cross-section in turn affect the flow geometry. Based on experimental studies, a lumped parameter system model is proposed for the collapsible tube. The mathematical model is simulated on a hybrid computer. Experimental data were used to define the functional relationship between cross-sectional area and transmural pressure as well as the relation between the energy loss coefficient and cross-sectional area. Computer results confirm the validity of the model for both steady and transient flow conditions. 相似文献
6.
Effects of plant size on photosynthesis and water relations in the desert shrub Prosopis glandulosa (Fabaceae) 总被引:1,自引:0,他引:1
Amrita G. de Soyza Augusto C. Franco Ross A. Virginia James F. Reynolds Walter G. Whitford 《American journal of botany》1996,83(1):99-105
The Jornada del Muerto basin of the Chihuahuan Desert of southern New Mexico, USA, has undergone a marked transition of plant communities. Shrubs such as mesquite (Prosopis glandulosa) have greatly increased or now dominate in areas that were previously dominated by perennial grasses. The replacement of grasses by shrubs requires an establishment phase where small shrubs must compete directly with similar-sized grass plants. This is followed by a phase in which large, established shrubs sequester nutrients and water within their biomass and alter soil resources directly under their canopy, creating “islands” of fertility. We hypothesized that these two phases were associated with shrubs having different physiological response capacities related to their age or size and the resource structure of the environment. As a corollary, we hypothesized that responses of small shrubs would be more tightly coupled to variation in soil moisture availability compared to large shrubs. To test these hypotheses, we studied gas exchange and water relations of small (establishing) and large (established) shrubs growing in the Jornada del Muerto as a function of varying soil moisture during the season. The small shrubs had greater net assimilation, stomatal conductance, transpiration, and xylem water potential than large shrubs following high summer rainfall in July, and highest seasonal soil moisture at 0.3 m. High rates of carbon assimilation and water use would be an advantage for small shrubs competing with grasses when shallow soil moisture was plentiful. Large shrubs had greater net assimilation and water-use efficiency, and lower xylem water potential than small shrubs following a dry period in September, when soil moisture at 0.3 m was lowest. Low xylem water potentials and high water-use efficiency would allow large shrubs to continue acquiring and conserving water as soil moisture is depleted. Although the study provides evidence of differences in physiological responses of different-sized shrubs, there was not support for the hypothesis that small shrubs are more closely coupled to variation in soil moisture availability than large shrubs. Small shrubs may actually be less coupled to soil moisture than large shrubs, and thus avoid conditions when continued transpiration could not be matched by equivalent water uptake. 相似文献
7.
Hendrik Wunderlich Roque Augusto Castro Alvaro Holger Wenschuh Karsten Schnatbaum 《Journal of peptide science》2023,29(11):e3496
Peptide purification by high-performance liquid chromatography (HPLC) is associated with high solvent consumption, relatively large effort and lack of efficient parallelization. As an alternative, many catch-and-release (c&r) purification methods have been developed over the last decades to enable the efficient parallel purification of peptides originating from solid-phase peptide synthesis (SPPS). However, with one exception, none of the c&r systems has been widely established in industry and academia until today. Herein, we present an entirely new chromatography-free purification concept for peptides synthesized on a solid support, termed reactive capping purification (RCP). The RCP method relies on the capping of truncation peptides arising from incomplete coupling of amino acids during SPPS with a reactive tag. The reactive tag contains a masked functionality that, upon liberation during cleavage from the resin, enables straightforward purification of the peptide by incubation with a resin-bound reactive moiety. In this work, two different reactive tags based on masked thiols were developed. Capping with these reactive tags during SPPS led to effective modification of truncated sequences and subsequent removal of the latter by chemoselective reaction with a maleimide-functionalized solid support. By introducing a suitable protecting group strategy, the thiol-based RCP method described here could also be successfully applied to a thiol-containing peptide. Finally, the purification of a 15-meric peptide by the RCP method was demonstrated. The developed method has low solvent consumption, has the potential for efficient parallelization, uses readily available reagents, and is experimentally simple to perform. 相似文献
8.
Bruno Moises de Matos Marco Augusto Stimamiglio Alejandro Correa Anny Waloski Robert 《World journal of stem cells》2023,15(5):453-465
Extracellular vesicles (EVs) are nanometric particles that enclose cell-derived bioactive molecules in a lipid bilayer and serve as intercellular communication tools. Accordingly, in various biological contexts, EVs are reported to engage in immune modulation, senescence, and cell proliferation and differentiation. Therefore, EVs could be key elements for potential off-the-shelf cell-free therapy. Little has been studied regarding EVs derived from human pluripotent stem cells (hPSC-EVs), even though hPSCs offer good opportunities for induction of tissue regeneration and unlimited proliferative ability. In this review article, we provide an overview of studies using hPSC-EVs, focusing on identifying the conditions in which the cells are cultivated for the isolation of EVs, how they are characterized, and applications already demonstrated. The topics reported in this article highlight the incipient status of the studies in the field and the significance of hPSC-EVs’ prospective applications as PSC-derived cell-free therapy products. 相似文献
9.
João Ricardo Sato Claudinei Eduardo Biazoli Ana Paula Arantes Bueno Arthur Caye Pedro Mario Pan Marcos Santoro Jessica Honorato-Mauer Giovanni Abrahão Salum Marcelo Queiroz Hoexter Rodrigo Affonseca Bressan Andrea Parolin Jackowski Euripedes Constantino Miguel Sintia Belangero Luis Augusto Rohde 《Genes, Brain & Behavior》2023,22(2):e12838
10.
Augusto C. Franco Angela Haag-Kerwer Britta Herzog Thorsten E. E. Grams Erika Ball Eduardo A. de Mattos Fabio R. Scarano Suzanne Barreto Maria A. Garcia Andre Mantovani Ulrich Lüttge 《Trees - Structure and Function》1996,10(6):359-365
Sandy plains are characteristic of the coastal region of Brazil. We investigated the diel patterns of changes in organic acid levels, leaf conductance and chlorophylla fluorescence for sun-exposed and shaded plants ofClusia hilariana, one of the dominant woody species in the sandy coastal plains of northern Rio de Janeiro state. Both exposed and shaded plants showed a typical CAM pattern with considerable diel oscillations in organic acid levels. The degradation of both malic and citric acids during the midday stomatal closure period could lead to potential CO2 fixation rates of 28 mol m-2 s-1 in exposed leaves. Moreover, exposed leaves exhibited large increases in total non-photochemical quenching (qN) accompanied by a substantial decrease in effective quantum yield during the course of the day. However, these potential high rates of CO2 fixation and the increases inqn of exposed plants were not enough to maintain the primary electron acceptor of photosystem II (qA) in a low reduction state, similar to that of shaded plants. As a result, there was a moderate increase in the reduction state of qA throughout the day. Most of the decline in photochemical efficiency of exposed leaves ofC. hilariana was reversible, as evidenced by the high levels of pre-dawn potential quantum yields (Fv/Fm) and their rapid recovery after sunset. However, the depletion of the organic acid pool in the afternoon resulted in an accentuated subsequent drop in Fv/Fm, suggesting that prolonged periods of water stress accompanied by high irradiance levels may expose plants ofC. hilariana in unprotected habitats to the danger of photoinhibition. 相似文献