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991.
Julieta Maya-Morales Guillermo Ibarra-Nú?ez Jorge L. León-Cortés Francisco Infante 《Journal of Insect Conservation》2012,16(1):25-38
We evaluated the spider diversity of a tropical montane cloud forest understory in two nearby sites with different degree
of human disturbance at the Biosphere Reserve Volcán Tacaná, Chiapas, Mexico. The study was conducted over a 24 days period
distributed in 6 months in 2009, covering dry and rainy seasons. A total of 8,370 spiders (1,208 adults and 7,162 juveniles)
were collected. Determined specimens (7,747) represented 112 species and morphospecies, 71 genera and 22 families. The results
showed that human disturbance has an influence on spider communities: species richness was significantly higher in the preserved
site as regards to the disturbed site. Despite their proximity, the composition of spider communities showed only a moderate
similarity between the two sites. No differences in abundance were found among sites when considering the whole sample, but
sites differed clearly when seasons were analyzed separately. The rainy season had a negative effect on the abundance of spiders
in the preserved site. Although the spider community structure was very similar between sites, there was a trend towards a
greater species evenness in the preserved site for the whole sampling period and for the dry season. 相似文献
992.
993.
Jorge A. Martínez-Villegas Alma Orozco-Segovia María Esther Sánchez-Coronado Irene Pisanty 《Plant Ecology》2012,213(5):871-881
Sedum oxypetalum is one of the dominant species in the xerophilous shrublands in the lava fields of the Basin of Mexico. Germination of this species was evaluated to understand its ecological response. We tested the effects of different pre-germination treatments (cold, and dry and wet heat) and storage time, as well as those of natural priming in two microhabitats with different disturbance levels. Experiments were performed in laboratory conditions under constant (25 °C) and fluctuating (20/30 °C) temperatures. Seeds did not germinate during burial and proved to be positively photoblastic. Under pre-germination treatments, final germination percentage was higher at 20/30 °C in seeds after four or more months of storage. None of the pre-germination treatments favored germination. Seeds can survive for more than 1 year and form a seed bank. Thus, seeds underwent natural priming that favored final germination percentage; however, germination rate and lag time were not affected by this process. In natural conditions, germination is delayed until the rainy season, improving the success of seedling establishment and growth. We discuss the role of fluctuating temperature in germination processes and the adaptations of seeds to their seasonal environment. 相似文献
994.
Marco A. Molina-Montenegro Jorge Gallardo-Cerda T. S. M. Flores Cristian Atala 《Plant Ecology》2012,213(1):133-142
The upper and poleward limit of tree distribution are usually determined by abiotic factors such as low temperature and strong
winds. Thus, cold resistance is a key element for survival in high altitudes and latitudes where conditions can reduce plant
growth. A trade-off between resource allocation to cold resistance and growth could emerge in populations frequently exposed
to low temperatures like those in the treeline zone. We studied annual height growth and ice nucleation temperature in Nothofagus pumilio (Nothofagaceae) populations growing in its extremes of altitudinal distribution and in 3 sites situated on a latitudinal
gradient in the Chilean Andes. Additionally, gas exchange, water and nitrogen use efficiency and total soluble sugar (TSS)
were also measured as possible mechanisms for survival in high altitudes. Individuals from the treeline populations showed
lower annual height growth and lower ice nucleation temperatures compared with those from lower populations. In the same way,
individuals from more poleward populations showed lower annual height growth and lower ice nucleation temperatures. Gas exchange,
water and nitrogen use efficiency and TSS were also higher in the high altitude populations. The results obtained support
the hypothesis of trade-off, because the upper and poleward populations showed more cold resistance but a lower height growth.
Additionally, we show that cold resistance mechanisms do not impact the physiological performance, suggesting possible adaptation
of the high altitude populations. Low temperatures may be affecting cellular growth instead of photosynthesis, creating a
pool of carbohydrates that could participate in cold tolerance. Other abiotic and biotic factors should be also assessed to
fully understand the distributional range of Nothofagus species. 相似文献
995.
Jorge Morales Pedraza Astrid Lobo Gajiwala María Esther Martinez Pardo 《Cell and tissue banking》2012,13(1):15-25
The IAEA International Standards for Tissue Banks published in 2003 were based on the Standards then currently in use in the
USA and the European Union, among others, and reflect the best practices associated with the operation of a tissue bank. They
cover legal, ethical and regulatory controls as well as requirements and procedures from donor selection and tissue retrieval
to processing and distribution of finished tissue for clinical use. The application of these standards allows tissue banks
to operate with the current good tissue practice, thereby providing grafts of high quality that satisfy the national and international
demand for safe and biologically useful grafts. The objective of this article is to review the IAEA Standards and recommend
new topics that could improve the current version. 相似文献
996.
Jorge Parodi Lenin Ochoa-de la Paz Ricardo Miledi Ataúlfo Martínez-Torres 《Molecules and cells》2012,34(4):349-355
Xenopus laevis oocytes exposed to amyloid-β aggregate generated oscillatory electric activity (blips) that was recorded by two-microelectrode voltage-clamp. The cells exhibited a series of “spontaneous” blips ranging in amplitude from 3.8 ± 0.9 nA at the beginning of the recordings to 6.8 ± 1.7 nA after 15 min of exposure to 1 μM aggregate. These blips were similar in amplitude to those induced by the channel-forming antimicrobial agents amphotericin B (7.8 ± 1.2 nA) and gramicidin (6.3 ± 1.1 nA). The amyloid aggregate-induced currents were abolished when extracellular Ca2+ was removed from the bathing solution, suggesting a central role for this cation in generating the spontaneous electric activity. The amyloid aggregate also affected the Ca2+-dependent Cl− currents of oocytes, as shown by increased amplitude of the transient-outward chloride current (Tout) and the serum-activated, oscillatory Cl− currents. Electron microcopy revealed that amyloid aggregate induced the dissociation of the follicular cells that surround the oocyte, thus leading to a failure in the electro-chemical communication between these cells. This was also evidenced by the suppression of the oscillatory Ca2+-dependent ATP-currents, which require proper coupling between oocytes and the follicular cell layer. These observations, made using the X. laevis oocytes as a versatile experimental model, may help to understand the effects of amyloid aggregate on cellular communication. 相似文献
997.
998.
Zuniga JM Housh TJ Camic CL Hendrix CR Mielke M Johnson GO Housh DJ Schmidt RJ 《Journal of strength and conditioning research / National Strength & Conditioning Association》2012,26(6):1651-1656
The purpose of this study was to examine the effects of 7 days of supplementation with 20 g·d?1 of creatine monohydrate (CM) on mean power (MP) and peak power (PP) from the Wingate anaerobic test (WAnT), body weight (BW), 1-repetition maximum (1RM) bilateral leg extension (LE) strength, and 1RM bench press (BP) strength. This study used a randomized, double-blind, placebo-controlled design. Twenty-two men (mean ± SD: age = 22.1 ± 2.0 years; height = 178.0 ± 5.8 cm; body weight [BW] = 77.6 ± 7.6 kg) were randomly assigned to either a supplement (SUPP; n = 10) or placebo (PLAC; n = 12) group. The SUPP group ingested 20 g·d?1 of CM powder for 7 days, whereas the PLAC ingested 20 g·d?1 of maltodextrin powder. Measurements for the PLAC and SUPP groups included BW, PP, and MP from two 30-second WAnTs (separated by 7 minutes), and 1RM strength for LE and BP. Testing was conducted before (PRE) and after (POST) 7 days of ingesting either the supplement or placebo. The results of this study indicated that there was a significant (p ≤ 0.05) increase from PRE to POST testing in MP for the SUPP group (5.4%) but not for the PLAC group (-0.3%). There were no between-group differences, however, for 1RM LE and 1RM BP strength. Furthermore, there were no changes in PP or BW for either group. The findings of this study indicated that loading with 20 g·d?1 of CM for 7 days increased MP (5.4% increase) from the WAnT, but it had no effect on strength (1RM LE and 1RM BP), PP, or BW. 相似文献
999.
Colado JC Garcia-Masso X Triplett TN Flandez J Borreani S Tella V 《Journal of strength and conditioning research / National Strength & Conditioning Association》2012,26(11):3018-3024
ABSTRACT: Colado JC, Garcia-Masso X, Triplett TN, Flandez J, Borreani S, Tella V. Concurrent validation of the OMNI-Resistance Exercise Scale of perceived exertion with Thera-Band resistance bands. J Strength Cond Res 26(11): 3018-3024, 2012-The concurrent validity of the OMNI-Resistance Exercise Scale (OMNI-RES) of perceived exertion for use with elastic bands was studied during isotonic resistance exercises. Twenty healthy, physically active subjects completed both familiarization and testing sessions. The criterion variables were myoelectric activity, recorded by electromyography, and heart rate, recorded by a heart rate monitor. The subjects performed 2 separate sets of 15 repetitions in each of the 2 testing sessions and for each of the exercises applied (i.e., frontal and lateral raises). One set was carried out with the separation between the hands gripping the elastic band allowing that 15 repetition maximum to be performed in the selected exercise, whereas the other set was carried out with the separation between hands at +50% of the previous grip. The perceived exertion rating for the active muscles and for the overall body, muscular activity, and heart rate were measured during the final repetition of each set. The results showed significant differences (p ≤ 0.001) in myoelectric activity, heart rate, and OMNI-RES scores between the low- and high-intensity sets and the intraclass correlation coefficient was 0.72-0.76. So it can be concluded that the OMNI-RES can be used for monitoring the intensity of exercises when elastic bands are used. This would allow the training stimulus dosage to be precisely controlled in both the session in progress and between different sessions, and allowing to differentiate between different levels of intensity according to the physical aptitudes and special physiological needs of the subjects. 相似文献
1000.
Fernandes AS Costa J Gaspar J Rueff J Cabral MF Cipriano M Castro M Oliveira NG 《Free radical research》2012,46(9):1157-1166
The unique redox and catalytic chemistry of Cu has justified the development of novel Cu complexes for different therapeutic uses including cancer therapy. In this work, four pyridine-containing aza-macrocyclic copper(II) complexes were prepared (CuL1-CuL4) varying in ring size and/or substituents and their superoxide scavenging activity evaluated. CuL3, the most active superoxide scavenger, was further studied as a modulator of the cytotoxicity of oxaliplatin in epithelial breast MCF10A cells and in MCF7 breast cancer cells. Our results show that CuL3 enhances the therapeutic window of oxaliplatin, by both protecting non-tumour cells and increasing its cytotoxic effect in breast carcinoma cells. CuL3 is thus a promising complex to be further studied and to be used as a lead compound for the optimization of novel chemotherapy sensitizers. 相似文献