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采用不同浓度的抗坏血酸(50—800μmol/L)和硫酸亚铁(2.5—40μmol/L)系统生成以羟自由基为主的各种程度氧胁迫,使之作用于人肝癌细胞。本文所采用的不同程度的氧胁迫均能抑制癌细胞的生长。低水平氧胁迫可使肝癌细胞失去某些恶性特征,趋向分化,表现为细胞表面对Con-A的凝集力、甲胎蛋白含量、γ-谷氨酰转肽酶和酪氨酸-α-酮戊二酸转氨基酶活性都朝着分化方向变化,差异显著。分化后的细胞克隆形成能力显著降低。在分化过程中,出现一定量的凋亡细胞。随着氧胁迫程度的增高,凋亡细胞增多,表现为非贴壁细胞增多,细胞体积变小,染色质凝缩在核膜边缘,呈新月形,核碎裂,但质膜完整。细胞核中DNA降解成大约21.2kbp大小的大片段DNA。有望通过严格控制氧胁迫程度来减慢肝癌细胞增殖,促进分化和凋亡,使恶性细胞逆转成良性细胞。 相似文献
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Environmental controls over carbon exchange of three forest ecosystems in eastern China 总被引:1,自引:0,他引:1
GUI‐RUI YU LEI‐MING ZHANG XIAO‐MIN SUN YU‐LING FU XUE‐FA WEN QIU‐FENG WANG SHENG‐GONG LI CHUAN‐YOU REN XIA SONG YUN‐FEN LIU SHI‐JIE HAN JUN‐HUA YAN 《Global Change Biology》2008,14(11):2555-2571
Net ecosystem productivity (NEP) was continuously measured using the eddy covariance (EC) technique from 2003 to 2005 at three forest sites of ChinaFLUX. The forests include Changbaishan temperate mixed forest (CBS), Qianyanzhou subtropical coniferous plantation (QYZ), and Dinghushan subtropical evergreen broad‐leaved forest (DHS). They span wide ranges of temperature and precipitation and are influenced by the eastern Asian monsoon climate to varying extent. In this study, we estimated ecosystem respiration (RE) and gross ecosystem productivity (GEP). Comparison of ecosystem carbon exchange among the three forests shows that RE was mainly determined by temperature, with the forest at CBS exhibiting the highest temperature sensitivity among the three ecosystems. The RE was highly dependent on GEP across the three forests, and the ratio of RE to GEP decreased along the North–South Transect of Eastern China (NSTEC) (i.e. from the CBS to the DHS), with an average of 0.77 ± 0.06. Daily GEP was mainly influenced by temperature at CBS, whereas photosynthetic photon flux density was the dominant factor affecting the daily GEP at both QYZ and DHS. Temperature mainly determined the pattern of the interannual variations of ecosystem carbon exchange at CBS. However, water availability primarily controlled the interannual variations of ecosystem carbon exchange at QYZ. At DHS, NEP attained the highest values at the beginning of the dry seasons (autumn) rather than the rainy seasons (summer), probably because insufficient radiation and frequent fog during the rainy seasons hindered canopy photosynthesis. All the three forest ecosystems acted as a carbon sink from 2003 to 2005. The annual average values of NEP at CBS, QYZ, and DHS were 259 ± 19, 354 ± 34, and 434 ± 66 g C m−2 yr−1, respectively. The slope of NEP that decreased with increasing latitude along the NSTEC was markedly different from that observed on the forest transect in the European continent. Long‐term flux measurements over more forest ecosystems along the NSTEC will further help verify such a difference between the European forest transect and the NSTEC and provide insights into the responses of ecosystem carbon exchange to climate change in China. 相似文献
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Abstract Little attention is paid to the behavioural and physiological adaptations of ant‐eating predators. It is expected that there should be a strong selection for traits related to prey handling, leading to the evolution of morphological, behavioural and nutritional adaptations. Such adaptations may then entail trade‐offs in handling and utilization of alternative prey. To investigate behavioural as well as nutritional adaptations and the occurrence of the corresponding trade‐offs in two ant‐eating spiders of the genus Zodarion [Zodarion atlanticum Pekár & Cardoso and Zodarion germanicum (C. L. Koch)], spiders are reared on two diets: ants (i.e. their preferred prey) and fruit flies (i.e. an alternative prey that is nutritionally optimal for euryphagous spiders). Food consumption is observed and several fitness‐related life‐history parameters are measured. Although spiders readily accept ants, more than one‐third of 35 spiders refuse to consume fruit flies and starve. Furthermore, severe hunger does not induce these individuals to accept fruit flies. Starving spiders die before moulting to the second stadium. Spiders that eat fruit flies increase only little and slowly in weight, and all of these die during the first two stadia. By contrast, spiders on an ant diet increase dramatically in weight, and develop up to the fourth stadium. These data indicate that fruit flies are not suitable for Zodarion, supporting the hypothesis that there are behavioural and nutritional trade‐offs. Taking into account the results of previous studies, it is suggested that nutritional trade‐offs are generally important for stenophagous spiders. 相似文献
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目的:探究血栓通配合康复训练对缺血性脑卒中(cerebral arterial thrombosis,CAT)恢复期患者肢体康复的疗效情况。方法:选取2011年3月-2013年3月我院收治的84例CAT患者按数字表法随机分为观察组和对照组,各42例。对照组单纯采用康复训练治疗,观察组在对照组康复训练的基础上服用血栓通配合治疗,分别观察治疗前、治疗后1个月、3个月、6个月的各项基本指标并对比研究。结果:两组患者治疗前和治疗1月后Barthel评分无明显差异(P0.05);观察组治疗后3、6个月Barthel评分显著高于对照组,差异有统计学意义(P0.05),两组患者治疗前和治疗1月后肢体Fugl-Meyer评分无明显差异(P0.05);观察组治疗后3、6个月肢体Fugl-Meyer评分显著高于对照组,差异有统计学意义(P0.05),且对照组出院时上肢依然未完全恢复。通过对对照组和观察组患者的生活质量评分比较,观察组生活质量的各项评分均明显高于对照组,两组比较差异有统计学意义(P0.05)。结论:对缺血性脑卒中恢复期患者采用血栓通药物配合适当的康复训练疗效较好,术后肢体恢复理想,值得作为治疗CAT的首选方法在临床上推广应用。 相似文献
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滞育是部分昆虫固有的适应逆境胁迫的遗传属性,七星瓢虫具有显著的滞育现象。本文以七星瓢虫雌成虫为试材,研究正常发育、滞育及滞育解除后3组处理试虫糖、脂、蛋白等关键代谢物质含量波动规律,总结滞育期间的代谢适应特点,解析其与过冷却能力的相关性,探索滞育对七星瓢虫逆境胁迫耐受力的促升效应,丰富七星瓢虫的滞育基础理论研究。利用物质干湿重差数法测定七星瓢虫的含水量;利用氯仿-甲醇(体积比为2∶1)法抽提除去自由水个体的脂肪;总糖、海藻糖、甘油、山梨醇及总蛋白的测定采用标准曲线法,利用SUN-II型智能昆虫过冷却点测定仪测定七星瓢虫的过冷却点(supercooling point,SCP)。结果表明,七星瓢虫滞育组含水量(58.11%±6.55%)显著低于正常发育组(68.49%±2.26%)和滞育解除组(65.84%±4.02%)(F=8.15,P0.01),滞育解除后含水量恢复至正常发育组水平;滞育组总糖(10.60±0.54μg/mg)、糖原(8.72±0.62μg/mg)、脂肪(173.66±19.01μg/mg)含量远远高于正常发育组和滞育解除组(F=46.57,P=0.0006;F=114.25,P0.0001;F=8.48,P0.01);滞育组总蛋白含量(49.20±3.80μg/mg)显著低于正常发育组(71.02±6.15μg/mg)和滞育解除组(69.45±4.66μg/mg)(F=46.57,P=0.0006);滞育组中海藻糖(1.31±0.27μg/mg)、甘油(1.74±0.50μg/mg)、山梨醇(9.84±3.02μg/mg)含量与正常发育组、滞育解除组无显著性差异(F=0.79,P=0.4946;F=1.33,P=0.3004;F=1.69,P=0.2387)。七星瓢虫在滞育条件下其过冷却点(-16.53℃±1.44℃)显著低于正常发育组(-14.07℃±1.33℃)和滞育解除组(-15.29℃±2.10℃)(F=13.47,P0.0001),经过滞育低温驯化后滞育解除组过冷却点较对照组有所降低。滞育诱发七星瓢虫发生显著的代谢适应,蛋白含量显著降低,抑制新陈代谢进程;糖脂含量显著升高,保障滞育维持及解除后发育的能量需求;七星瓢虫滞育属糖原积累型;滞育个体过冷却点大幅下降,耐寒性显著提升。 相似文献
99.
母猪分娩期间的母性行为对新生仔猪的成活致关重要,失败的母性行为如杀婴行为和压仔行为等经常在一些母猪中发生,给养猪业造成巨大的经济损失,给仔猪福利带来严重影响。前列腺素F2α不但可促发母猪产前的做窝行为,而且通过其受体基因(PTGFR)编码的蛋白FP在母猪繁殖过程和母性行为中发挥重要作用。文章以白色杜洛克×二花脸资源群体为材料,对PTGFR基因进行了SNP搜寻并分析其与母猪产前做窝行为、产后杀婴行为和压仔行为的关联性。结果:在PTGFR基因的两个外显子中共搜寻到5个同义突变SNP。选择Exon1g.250AG、Exon1g.619GA和Exon2g.483TC3个SNP在F0、F1个体和289头F2母猪中进行了基因型判定。基于家系基础上的传递不平衡(TDT)分析结果显示,PTGFR基因的3个SNP及单倍型与母猪做窝行为、杀婴行为和压仔行为均未达到显著相关(P0.05)。所以PTGFR基因可能并不是影响母猪母性行为的主效候选基因。 相似文献
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