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131.
Screening of a cDNA library constructed under alkaline pH mediated growth of Aspergillus oryzae implicated a vacuolar H+-ATPase gene (vmaA) as a putative candidate involved in alkaline pH adaptation. A. oryzae vmaA genomic DNA extended to 2072 bp including three introns and encoded a protein of 605 amino acids. VmaAp was homologous to Vma-1p from Neurospora crassa (71%), Vma1p from Saccharomyces cerevisiae (69%) and ATP6A2 from human (49%). The vmaA cDNA complemented S. cerevisiae V-ATPase disrupted strain (Deltavma1) was viable at alkaline pH 8.0 and in the presence of CaCl(2) (100 mM). Northern analysis revealed an enhanced expression of vmaA during growth of A. oryzae in alkaline medium (pH 10.0). The A. oryzae vmaA disruptant exhibited abnormally shrunken vacuoles and hyphal walls at pH 8.5 and a growth defect at pH 10.0, implicating an alkaline pH stress responsive role for vmaA in A. oryzae. 相似文献
132.
133.
This study evaluated the effects of an acute change in water pH (from pH 7.5 to 4.0, 5.0, 6.0, 7.5, 8.0 or 9.0) on several biochemical parameters in juveniles of the silver catfish, Rhamdia quelen. Ammonia levels decreased in the liver and increased in the muscle with increasing water pH. In the kidney, lower ammonia levels were observed at neutral pH. An increase in water pH decreased the glucose, glycogen and lactate levels in the liver and kidney (except for glycogen levels in the kidney and lactate levels in the liver, which presented lower levels at neutral pH). In muscle, the glucose and glycogen levels decreased with increasing water pH, whereas lactate levels tended to be lower at neutral pH. Gill and kidney Na+/K+-ATPase activities tended to increase in alkaline water, and the highest value was observed in fish exposed to pH 9.0. The optimal levels of the analyzed biochemical parameters occurred at neutral pH. In conclusion, exposure to acidic and alkaline pH changes the metabolic parameters of silver catfish as well as gill Na+/K+-ATPase activity. 相似文献
134.
链霉菌Z94-2碱性脂肪酶产生条件及酶学性质 总被引:2,自引:0,他引:2
在152株脂肪酶产生菌中,链霉菌Z94-2产脂肪酶活力为596u/mL,其最适培养基(g/L)为:糊精10、黄豆饼粉30、尿素10、K2HPO40.5、MgSO40.5、NaCl1和AEO90.5,产酶的最适条件为:初始pH9.5~10.0,在26℃培养48h。用PVA橄榄油乳化系统测定该酶的最适pH9.8,最适温度37℃,在pH8.6~10.2于5℃存放24h,酶活力不变。0.14mol/L的氯 相似文献
135.
Vanadate has been recognized as a specific and potent phosphatase inhibitor since its structure is similar to that of phosphate. In this study, we measured the inhibition of glutathione S-transferase-tagged protein tyrosine phosphatase 1B (GST-PTP1B) and alkaline phosphatase (ALP) by the insulin enhancing compounds, bis(maltolato)oxovanadium(IV) (BMOV). The results showed that the activity of GST-PTP1B was reversibly inhibited by solutions of BMOV with an IC50 value of 0.86 ± 0.02 μM. Steady state kinetic studies showed that inhibition of GST-PTP1B by BMOV was of a mixed competitive and noncompetitive type. In addition, incubation of GST-PTP1B with BMOV showed a time-dependent biphasic inactivation of the protein. On the other hand, the inhibitory behavior of BMOV on ALP activity was reversible and competitive with an IC50 value of 32.1 ± 0.6 μM. Incubation with BMOV did not show biphasic inactivation of ALP. The reversible inhibition of GST-PTP1B by BMOV is more potent than that of ALP, but solutions of BMOV inhibited both enzymes. This data support the suggestion that mechanisms for the inhibitory effects of BMOV on GST-PTP1B and ALP are very different. 相似文献
136.
Javier Arias 《Inorganica chimica acta》2011,365(1):501-504
The crown ether isocyanide CNR (R = benzo-15-crown-5) reacts with silver(I) salts in the appropriate molar ratio to give [Ag(CNR)n]X (n = 1, 2; X = CF3SO3, BF4). X-ray diffraction studies of [Ag(CF3SO3)(CNR)] show the molecules associated in a dinuclear manner with an antiparallel orientation. The silver centers are tetracoordinated to the isocyanide and to three oxygens, one from the triflate anion and two from the second crown ether in the dimer. The molecular structure displays five cycles: the two 15-crown ether rings, two five-membered argentacycles and a 22-membered diargentacycle. The crown ether in these complexes is able to detect alkaline cations from M(CF3SO3) (M = Li, Na, K) by NMR in d6-acetone solutions, and to distinguish Li+-Na+ from K+. 相似文献
137.
中温碱性脂肪酶的研究——Ⅲ.扩展青霉PF868变株碱性脂肪酶的纯化及其酶学性质 总被引:1,自引:0,他引:1
扩展青霉PF868变株发酵液经硫酸铵盐析和Sephadex-G-200及Sepharose4B柱层析纯化,获得纯化倍数为32.4的酶粉.该酶分子量为23442Dal.酶学特性表明:该酶的最适作用温度为32℃,50℃保温30min仍保留50%酶活性,最适pH为9.0,作用pH稳定范围在7.0—10.0之间.Ca~(2+)Mg~(2+)对酶有激活作用.Fe~(2+)、Cu~(2+)和Mn~(2+)对酶活力有抑制作用. 相似文献
138.
在地衣芽孢杆菌NCIB 6816菌株碱性蛋白酶基因已知序列的基础上,通过设计合适的引物,利用PCR(Polymerase Chain Reaction)技术从地衣芽孢杆菌2709菌株的柒色体DNA中扩增了2709碱性蛋白酶的编码序列。对两个克隆的PCR片段的全序列分析结果显示,2709碱性蛋白酶的编码序列同相应的NCIB 6816序列相比有3%左右的碱基组成差异。由此推定的2709碱性蛋白酶的氨基酸序列肯定了2709碱性蛋白酶属典型的subtilisin Carlsberg类,同时还表明来源于不同地衣芽孢杆菌菌株的subtilisin Carlsberg存在着若干氨基酸组成上的差异。 相似文献
139.
松嫩平原碱化草地植物群落分布的空间和环境因素分析 总被引:8,自引:1,他引:8
在1996年野外实地采样的基础上,运用DCA消势对应分析(detrendedcorespondenceanalysis)对群落主要变化趋势及其与土壤环境因子之间的关系进行了分析。运用DCCA消势典范对应分析(detrendedcanonicalcorespondenceanalysis)对影响松嫩平原碱化草地群落结构季节动态的空间和环境因素进行了定量的分解。结果表明:在影响群落分布的各因子中,环境因子独立约占40%,而环境_空间耦合因子占35%,空间因子独立约占3%,其他因子约占20%。在诸多因子中,土壤的盐渍化程度在整个生长季起着决定性作用,但土壤水分和氮素的作用因季节而变化。在干旱季节,植物生长的主要制约因子为土壤碱化度和土壤水分,而土壤氮素的作用处于次要地位。但在降雨较多、土壤湿润度较大的季节,土壤氮素的影响明显增强,成为仅次于土壤碱化度的决定性因素。 相似文献
140.
Tobacco hornworm, Manduca sexta, is a model insect for studying the action of Bacillus thuringiensis (Bt) Cry toxins on lepidopterans. The proteins, which bind Bt toxins to midgut epithelial cells, are key factors involved in the insecticidal functions of the toxins. Three Cry1A-binding proteins, viz., aminopeptidase N (APN), the cadherin-like Bt-R1, and membrane-type alkaline phosphatase (m-ALP), were localized, by immunohistochemistry, in sections from the anterior, middle, and posterior regions of the midgut from second instar M. sexta larvae. Both APN and m-ALP were distributed predominantly along microvilli in the posterior region and to a lesser extent on the apical tip of microvilli in the anterior and middle regions. Bt-R1 was localized at the base of microvilli in the anterior region, over the entire microvilli in the middle region, and at both the apex and base of microvilli in the posterior region. The localization of rhodamine-labeled Cry1Aa, Cry1Ab, and Cry1Ac binding was determined on sections from the same midgut regions. Cry1Aa and Cry1Ab bound to the apical tip of microvilli almost equally in all midgut regions. Binding of Cry1Ac was much stronger in the posterior region than in the anterior and middle regions. Thus, binding sites for Bt proteins and Cry1A toxins are co-localized on the microvilli of M. sexta midgut epithelial cells. 相似文献