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71.
M.M. Kraïem C. Ben Hamza M. Ramdani A.A. Fathi H.M.A. Abdelzaher R.J. Flower 《Aquatic Ecology》2001,35(3-4):335-345
Age and growth characteristics of the thin-lipped Grey Mullet (Liza ramada) were investigated in three North African wetland lakes: Merja Zerga (Morocco), Garâat Ichkeul (Tunisia) and Edku Lake (Egypt). Age structure of the mullet populations was very similar in all three study lakes. Small differences in growth were indicated, especially for the Moroccan population, where growth tended to be slower than for the other two populations. The fastest growth was observed in the Edku population while the best condition was observed in the Ichkeul population. Compared with some European populations, the sampled North African populations have faster growth and better condition factors. 相似文献
72.
Moussaïd M Guillot EG Moreau M Fehrenbach J Chabiron O Lemercier S Pettré J Appert-Rolland C Degond P Theraulaz G 《PLoS computational biology》2012,8(3):e1002442
In human crowds as well as in many animal societies, local interactions among individuals often give rise to self-organized collective organizations that offer functional benefits to the group. For instance, flows of pedestrians moving in opposite directions spontaneously segregate into lanes of uniform walking directions. This phenomenon is often referred to as a smart collective pattern, as it increases the traffic efficiency with no need of external control. However, the functional benefits of this emergent organization have never been experimentally measured, and the underlying behavioral mechanisms are poorly understood. In this work, we have studied this phenomenon under controlled laboratory conditions. We found that the traffic segregation exhibits structural instabilities characterized by the alternation of organized and disorganized states, where the lifetime of well-organized clusters of pedestrians follow a stretched exponential relaxation process. Further analysis show that the inter-pedestrian variability of comfortable walking speeds is a key variable at the origin of the observed traffic perturbations. We show that the collective benefit of the emerging pattern is maximized when all pedestrians walk at the average speed of the group. In practice, however, local interactions between slow- and fast-walking pedestrians trigger global breakdowns of organization, which reduce the collective and the individual payoff provided by the traffic segregation. This work is a step ahead toward the understanding of traffic self-organization in crowds, which turns out to be modulated by complex behavioral mechanisms that do not always maximize the group's benefits. The quantitative understanding of crowd behaviors opens the way for designing bottom-up management strategies bound to promote the emergence of efficient collective behaviors in crowds. 相似文献
73.
74.
Carlo Capelli Guglielmo Antonutto Paola Zamparo Massimo Girardis Pietro Enrico di Prampero 《European journal of applied physiology and occupational physiology》1993,66(3):189-195
The mechanical power (Wtot, W·kg–1) developed during ten revolutions of all-out periods of cycle ergometer exercise (4–9 s) was measured every 5–6 min in six subjects from rest or from a baseline of constant aerobic exercise [50%–80% of maximal oxygen uptake (VO2max)] of 20–40 min duration. The oxygen uptake [VO2 (W·kg–1, 1 ml O2 = 20.9 J)] and venous blood lactate concentration ([la]b, mM) were also measured every 15 s and 2 min, respectively. During the first all-out period, Wtot decreased linearly with the intensity of the priming exercise (Wtot = 11.9–0.25·VO2). After the first all-out period (i greater than 5–6 min), and if the exercise intensity was less than 60% VO2max, Wtot, VO2 and [la]b remained constant until the end of the exercise. For exercise intensities greater than 60% VO2max, VO2 and [la]b showed continuous upward drifts and Wtot continued decreasing. Under these conditions, the rate of decrease of Wtot was linearly related to the rate of increase of V [(d Wtot/dt) (W·kg–1·s–1) = 5.0·10–5 –0.20·(d VO2/dt) (W·kg–1·s–1)] and this was linearly related to the rate of increase of [la]b [(d VO2/dt) (W·kg–1·s–1) = 2.310–4 + 5.910–5·(d [la]b/dt) (mM·s–1)]. These findings would suggest that the decrease of Wtot during the first all-out period was due to the decay of phosphocreatine concentration in the exercising muscles occurring at the onset of exercise and the slow drifts of VO2 (upwards) and of Wtot (downwards) during intense exercise at constant Wtot could be attributed to the continuous accumulation of lactate in the blood (and in the working muscles). 相似文献
75.
Leach MC Klaus K Miller AL Scotto di Perrotolo M Sotocinal SG Flecknell PA 《PloS one》2012,7(4):e35656
Background
Current behaviour-based pain assessments for laboratory rodents have significant limitations. Assessment of facial expression changes, as a novel means of pain scoring, may overcome some of these limitations. The Mouse Grimace Scale appears to offer a means of assessing post-operative pain in mice that is as effective as manual behavioural-based scoring, without the limitations of such schemes. Effective assessment of post-operative pain is not only critical for animal welfare, but also the validity of science using animal models.Methodology/Principal Findings
This study compared changes in behaviour assessed using both an automated system (“HomeCageScan”) and using manual analysis with changes in facial expressions assessed using the Mouse Grimace Scale (MGS). Mice (n = 6/group) were assessed before and after surgery (scrotal approach vasectomy) and either received saline, meloxicam or bupivacaine. Both the MGS and manual scoring of pain behaviours identified clear differences between the pre and post surgery periods and between those animals receiving analgesia (20 mg/kg meloxicam or 5 mg/kg bupivacaine) or saline post-operatively. Both of these assessments were highly correlated with those showing high MGS scores also exhibiting high frequencies of pain behaviours. Automated behavioural analysis in contrast was only able to detect differences between the pre and post surgery periods.Conclusions
In conclusion, both the Mouse Grimace Scale and manual scoring of pain behaviours are assessing the presence of post-surgical pain, whereas automated behavioural analysis could be detecting surgical stress and/or post-surgical pain. This study suggests that the Mouse Grimace Scale could prove to be a quick and easy means of assessing post-surgical pain, and the efficacy of analgesic treatment in mice that overcomes some of the limitations of behaviour-based assessment schemes. 相似文献76.
目的:探讨激活多巴胺Ⅰ类受体(DR1)对氧化型低密度脂蛋白(ox-LDL)诱导的人单核细胞(THP-1)分泌一氧化氮/一氧化氮合酶(NO/NOS)的影响及可能机制。方法:THP-1细胞经佛波酯PMA诱导分化,分为正常对照组(control),氧化型低密度脂蛋白处理组(ox-LDL),DR1激动剂干预组(SKF),DR1阻断剂干预组(SCH),ERK阻断剂干预组(PD98059);应用油红O染色法鉴定泡沫细胞;硝酸还原法检测NO、NOS的变化情况;免疫荧光和Western blot检测各组细胞蛋白表达情况。结果:ox-LDL刺激48 h可形成泡沫细胞;DR1在THP1细胞上表达,ox-LDL刺激后,DR1蛋白表达降低(P<0.01);激活DR1受体能够明显抑制由ox-LDL引起的NO、iNOS增多(P<0.01);在MAPK阻断剂PD98059存在的情况下,SKF的作用部分丧失。结论:激活DR1受体可抑制ox-LDL引起的THP-1细胞NO的大量产生,此过程可能由ERK信号通路所介导。 相似文献
77.
78.
Roovers RC van der Linden E de Bruïne AP Arends JW Hoogenboom HR 《Cancer immunology, immunotherapy : CII》2001,50(1):51-59
Antibodies to tumour-associated antigens are increasingly being used as targeting vehicles for the visualisation and for
therapy of human solid tumours. The epithelial cell adhesion molecule (Ep-CAM) is an antigen that is overexpressed on a variety
of human solid tumours and constitutes an attractive target for immunotargeting. We set out to obtain fully human antibodies
to this antigen by selecting from a large antibody repertoire displayed on bacteriophages. Two single-chain variable antibody
fragments (scFv) were identified that specifically bound recombinant antigen in vitro. One of the selected antibodies (VEL-1)
cross-reacted with extracellular matrix components in immunohistochemistry of colon carcinoma, whereas the other scFv (VEL-2)
specifically recognised colon cancer cells. The latter antibody was further characterised with respect to epitope specificity
and kinetics of antigen-binding. It showed no competition with the well-characterised anti Ep-CAM MOC-31 monoclonal antibody
and had an off-rate of 5 × 10−2 s−1. To obtain an antibody format more suitable for in vivo tumour targeting and to increase the apparent affinity through avidity,
the genes of scFv VEL-2 were re-formatted by fusion to a human (γ1) hinge region and CH3 domain. This “minibody” was expressed
in Escherichia coli, specifically bound the Ep-CAM antigen and showed a 20-fold reduced off-rate in surface plasmon resonance analysis. These
results show that phage antibody selection, combined with antibody engineering, may result in fully human antibody molecules
with promising characteristics for in vivo use in tumour targeting.
Received: 13 July 2000 / Accepted: 12 October 2000 相似文献
79.
Mohamed Saïd Hifnawy Jacqueline Vaquette Thierry Sévenet Jean-Louis Pousset André Cavé 《Phytochemistry》1977,16(7):1035-1039
Stems and leaves of Myrtopsis macrocarpa, M. myrtoidea, M. novae-caledoniae and M. sellingii yielded terpenes, sterols, coumarins, alkaloids (furoquinolines and quinolones) and amides. A new quinolone (8-methoxy flindersine) occurs in Myrtopsis macrocarpa, a new amide (N-benzoyltryptamine) in M. myrtoidea, two new coumarins (myrsellin and myrsellinol) and a new dihydrofuroquinoline (myrtopsine) in M. sellingii. Structures of the new compounds are proposed from chemical and spectroscopic evidence. 相似文献
80.
Phylogeny and substitution rates of angiosperm actin genes 总被引:12,自引:1,他引:12
Forty-four actin genes from five angiosperm species were PCR-amplified,
cloned, and sequenced. Phylogenetic analysis of 34 of these actins, along
with those previously published, indicates that angiosperm actin genes are
monophyletic and underwent several duplications during evolution.
Orthologues have been identified between Solanaceae species, as well as
between Solanaceae species and soybean. These sequences were used to
calculate nucleotide substitution rates. The synonymous rate (6.96 x 10(-9)
substitutions/site/year) is similar to that of other nuclear protein-coding
genes, but the nonsynonymous rate (0.19 x 10(-9) substitutions/site/year)
is 6-19 times higher than that of mammalian actin genes. Relative rate
tests indicate that actin genes are evolving at similar rates in monocots
and in dicots. Evidence is also presented that some members of the maize
actin multigene family have been involved in gene conversion events, that
the potato genome contains 24 +/- 12 actin genes, and that potato and
tomato diverged 11.6 +/- 3.6 MYA.
相似文献