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61.
A temperature increase from 35° to 40–42°C enhances the rise of cytoplasmic serine proteinase (ISP1) activity in Bacillus megaterium incubated in a sporulation medium. A temperature shift from 27°C in the growth medium to 35°C in the sporulation medium has the same effect. Elevated temperature stimulates the increase of ISP1 level when applied immediately after the transfer of cells from the growth to the sporulation medium (at T0) or at T3, when sporulation becomes irreversible. The cytoplasmic PMSF-resistant activity or the proteolytic activity associated with the membrane fraction is stimulated only slightly or not at all. A temperature increase to 45–47°C suppresses the rise of proteolytic activities in all cell fractions. In addition to the elevation of the ISP1 activity by an upward temperature shift, the rise of this enzyme in nongrowing cells is also stimulated by osmotic stress. In growing populations, in contrast to the rise of the ISP1 activity caused by elevated temperature in nongrowing cells, this proteinase is induced by low temperatures (24–27°C). The ISP1 activity roughly correlates with the enzyme protein concentration determined by immunoblotting. 相似文献
62.
Thérèse M. Delahunty Ji Y. Jiang Raiford T. Black Bruce G. Lyeth 《Neurochemical research》1995,20(4):405-411
In the fluid percussion model of traumatic brain injury (TBI), we examined muscarinic and metabotropic glutamate receptor-stimulated polyphosphoinositide (PPI) turnover in rat hippocampus. Moderate injury was obtained by displacement and deformation of the brain within the closed cranial cavity using a fluid percussion device. Carbachol and (±)-1-Aminocyclopentane-trans-1,3.-dicarboxylic acid (trans-ACPD)-stimulated PPI hydrolysis was assayed in hippocampus from injured and sham-injured controls at both 1 hour and 15 days following injury. At 1 hour after TBI, the response to carbachol was enhanced in injured rats by up to 200% but the response to trans-ACPD was diminished by as much as 28%. By contrast, at 15 days after TBI, the response to carbachol was enhanced by 25% and the response to trans-ACPD was enhanced by 73%. The ionotropic glutamate agonists N-methyl-D-aspartate (NMDA), and -amino-3 hydroxy-5-methyl-4-isoxazolepropionate (AMPA), did not increase PPI hydrolysis in either sham or injured rats and injury did not alter basal hydrolysis. Thus, hippocampal muscarinic and metabotropic receptors linked to phospholipase C are differentially altered by TBI.Abbreviations used TBI
traumatic brain injury
- EAA
excitatory amino acids
- PPI
polyphosphoinositides
- IP
inositol phosphates
- NMDA
N-methyl-D-aspartate
- AMPA
-amino-3-hydroxy-5-methylisoxazole-4-propionate
- trans-ACPD
(±)-1-Aminocyclopentanetrans-1,3-dicarboxylic acid
- LTP
long term potentiation 相似文献
63.
64.
海马内生长抑素与γ-氨基丁酸在大鼠穿梭箱主动回避反应中的作用 总被引:1,自引:0,他引:1
本实验以大鼠穿梭箱主动回避反应(AAR)的习得和消退为学习记忆的指标,研究了海马内生长抑素(SS)和γ-氨基丁酸(GABA)在学习记忆中的作用。结果如下:(1)经训练而建立了AAR的大鼠,其海马内SS较对照组显著增高,而海马内GABA含量却明显降低;(2)海马内注入SS的耗竭剂半胱胺(Cys,20g/L)使大鼠AAR的习得受到明显损害,AAR的消退显著加速,海马内SS明显降低,而GABA含量却显著升高;(3)海马内注入GABA(200g/L)使大鼠AAR的消退显著加速的同时,其海马内SS含量亦显著降低。由此表明,海马内SS可能有促进学习记忆的作用,而海马内GABA升高则有相反的效应;二者在海马调控学习记忆过程中具有重要作用。 相似文献
65.
66.
67.
Jiří Ponert 《Folia Geobotanica》1977,12(1):9-22
Studies of the Adjarian flora resulted in a detailed classification of the ergasiophygophytes, based mainly on the degree of their naturalization: (1) The ephemeroergasiophygophytes display unstable naturalization both in artificial and natural habitats, and disappear after only a few growing seasons. (2) The deuteroergasiophygophtes show stable naturalization in anthropogenic habitats. (3) The protoergasiophygophytes are distinguished by uncertain stability of naturalization in natural habitats, and, if firmly naturalized on a certain spot, they lack any tendency to further spreading. (4) The autergasiophygophytes tend to spread in natural habitats. (5) The aggressive ergasiophygophytes transform natural vegetation in new plant communities, and can become dominant species in these communities. New terms, viz. emphemeroxenophytes, protoneophytes, non-aggressive neophytes, slightly aggressive neophytes, and postneophytes with vegetative reproduction have also been introduced to express diverse features of the xenophytes. 相似文献
68.
肌醇磷脂代谢与V-mos癌基因转化细胞的相关性,迄今为止未见报导。本文用6m2细胞(Moloney鼠类肉瘤病毒(含V-mos)温度敏感突变株(MoMuSVts110)转化的NRK细胞)为模型,探讨了肌醇磷脂代谢与细胞转化的相关性。在33℃ (转化型温度)时,细胞内PIP(磷脂酰肌醇-4-磷酸)含量明显高于39℃(正常型温度),显示出转化型6m2细胞中存在一个提高的PI激酶活性。同时可见DG(二酰甘油)和IP_3(肌醇三磷酸)含量和蛋白激酶C(PKC)活性均明显高于正常型细胞。当细胞由39℃转至33℃10min,PIP、DG、IP_3含量和PKC活性均明显增加,并伴随有PKC活性由胞质向质膜上的转移。实验结果表明肌醇磷脂代谢参与了6m2细胞转化过程。文中对其作用机理进行了讨论。 相似文献
69.
70.
The β-carboxylic group in N-dialkylphosphorylated aspartic acid has an activating effect that gives rise to peptides, esters, and ester exchange at the phosphoryl group. In contrast, the γ-carboxylic group of N-alkylphosphorylated glutamic acid has a much smaller effect. Some of the self-activating products were isolated and many model compounds were synthesized to study the novel activating effect of the β-carboxylic group. Mixed anhydride intermediates derived from α-carboxylphosphoryl and β-carboxylphosphoryl groups are proposed for the self-activation mechanism. 相似文献