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71.
Lauffenburger DA Chu L French A Oehrtman G Reddy C Wells A Niyogi S Wiley HS 《Biotechnology and bioengineering》1996,52(1):61-80
Peptide growth factors and other receptor-binding cytokine ligands are of interest in contemporary molecular health care approaches in applications such as wound healing, tissue regeneration, and gene therapy. Development of effective technologies based on operation of these regulatory molecules requires an ability to deliver the ligands to target cells in a reliable and well-characterizable manner. Quantitative information concerning the fate of peptide ligands within tissues is necessary for adequate interpretation of experimental observations at the tissue level and for truly rational engineering design of ligand-based therapies. To address this need, we are undertaking efforts to elucidate effects of key molecular and cellular parameters on temporal and spatial distribution of cytokines in cell population and cell/matrix systems. In this article we summarize some of our recent findings on dynamics of growth factor depletion by cellular endocytic trafficking, growth factor transport through cellular matrices, and growth factor production and release by autocrine cell systems. (c) 1996 John Wiley & Sons, Inc. 相似文献
72.
TheGPX2gene codes for GSHPx-GI, a glutathione peroxidase whose mRNA is readily detectable in the gastrointestinal tract. AlthoughGPX2is a single gene in humans, there are two genes in the mouse genome with homology toGPX2.By analyzing a panel of mouse interspecies DNA from the Jackson Laboratory's backcross resource, we have chromosomally mapped these two genes. One was mapped to the central region of mouse chromosome 12 betweenD12Mit4andD12Mit5,nearfosandTgfb3.This region is homologous to human 14q24.1, where humanGPX2has been mapped, and most likely represents the functional mouseGpx2gene. The otherGpx2-like gene was mapped to mouse chromosome 7 betweenPcsk3andHbb.We have isolated the latter gene from a P1 phage library. Its pseudogene nature is revealed by the sequence analysis: (a) it is intronless; (b) it has a single nucleotide deletion in the coding region; and (c) it has a poly(A) tail at its 3′-untranslated region. 相似文献
73.
本文用一氧化氮合酶(NOS)的组织化学方法对胎龄15周至36周的人胎视网膜含NOS神经元的发育进行了研究。胚胎15周视网膜颞侧半少部分神经元即有NOS的表达,20周视网膜含NOS神经元数密度达峰值。大部分含NOS神经元胞体位于内核层内带,只少部分位于节细胞层,其突起均分布于内同层,形成内同层的1、3、5亚层。含NOS神经元的形态各异,依据其突起的多少分Ⅰ、Ⅱ、Ⅲ等三种类型,其中Ⅱ、Ⅲ型含NOS神经元在28周以后才开始出现,且愈近晚期胎龄,它们所占含NOS神经元的数量比呈上升趋势。随视网膜发育成熟,含NOS神经元胞体均面积呈不断增大的变化。本文结果显示:人胎视网膜内核层含NOS神经元为无长突细胞,节细胞层的Ⅰ型含NOS神经元为移位无长突细胞,推测它们在视网膜的发育过程中对内网层突触的形成与修饰可能起有重要作用。 相似文献
74.
利用人粒细胞集落刺激因子(hG-CSF)cDNA3′端非翻译区(3′-UTR)中存在的DraⅠ酶切位点,通过部分酶切与完全酶切,删除3′-UTR不同长度,构建了四种hG-CSFcDNA瞬时重组表达质粒。转染COS-7细胞后,生物活性测定结果提示,hG-CSFcDNA3′-UTR对其表达起负调控作用,其关键性序列位于紧接终止密码子TGA下游的65bp范围内,3′-UTR对hG-CSFcDNA表达的影响与转录水平的差别有一定关系。 相似文献
75.
利用KCN、H_2O2和SDS的选择性反应引起的SOD同工酶谱带变化即可鉴别粗抽提液中的SOD同工酶类型;用这种方法对五株不同种根霉的鉴别实验表明,它们均不同程度地含有Cu,Zn型和Mn型两种SOD,前者约占80%左右,后者只占20%左右。用邻苯三酚自氧化法对样品中SOD活性测定结果与在同工酶谱上的鉴别结果基本一致。 相似文献
76.
Simultaneous occurrence of fumonisin B1 and other mycotoxins in moldy corn collected from the People's Republic of China in regions with high incidences of esophageal cancer. 总被引:7,自引:1,他引:6
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A total of 31 corn samples collected from households in the counties of Cixian and Linxian of the People's Republic of China, where high incidences of esophageal cancer have been reported, were analyzed for fumonisin B1 (FB1), aflatoxin, and total trichothecene mycotoxins. High levels of FB1 (18 to 155 ppm; mean, 74 ppm) were found in 16 of the samples that showed heavy mold contamination. FB1, at lower levels (20 to 60 ppm; mean, 35.3 ppm), was also found in 15 samples, collected from the same households, that did not show any visible mold contamination. The levels of aflatoxin in the samples were low (1 to 38.4 ppb; mean, 8.61 ppb). High levels of total type-A trichothecenes were also found in the moldy corn samples (139 to 2,030 ppb; mean, 627 ppb). Immunochromatography of selected samples revealed that these samples contained T-2 toxin, HT-2 toxin, iso-neosolaniol, monoacetoxyscirpenol, and several other type-A trichothecenes. The concentration of total type-B trichothecenes in 15 moldy corn samples was in the range of 470 to 5,826 ppb (mean, 2,359 ppb). High levels (3.7 to 5.0 mg/g) of FB1 were produced in corn in the laboratory by five Fusarium moniliforme strains isolated from the moldy corn. These fungi were also capable of forming various nitrosamines (5 to 16 micrograms per flask) in the presence of nitrate and precursor amines.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
77.
Dong-Her Wu Chiou-Yen Wen Long-Liu Lin Wen-Shen Chu Wen-Hwei Hsu 《Letters in applied microbiology》1994,19(2):67-69
The isoamylase activity of Pseudomonas amyloderamosa WU 5315 was stable over the pH range from 5.5 to 6.25 while only about 30% of the activity remained at pH 6.5. Low isoamylase activity (418 U ml-1 ) was produced by the cells grown at high pH. Activity reached almost 3000 U ml-1 when pH was kept below 6.0 during the fermentation. With 1% glucose plus 2% maltose instead of 3% maltose as carbon source, however, no pH control was required and the isoamylase activity of Ps. amyloderamosa WU 5315 increased to 3400 U ml-1 . 相似文献
78.
本文对作者本人在1983年《中国植物志》第76卷第一分册12l页上针对川甘亚菊处理过宽的问题,重新作出了订正。本文确认川甘亚菊、灰叶亚菊、深裂亚菊及下白亚菊分别为不同的种,并作出了这四个种的分种检索表。 相似文献
79.
Direct sequencing of the mitochondrial displacement loop (D-loop) of shrews
(genus Sorex) for the region between the tRNA(Pro) and the conserved
sequence block-F revealed variable numbers of 79-bp tandem repeats. These
repeats were found in all 19 individuals sequenced, representing three
subspecies and one closely related species of the masked shrew group (Sorex
cinereus cinereus, S. c. miscix, S. c. acadicus, and S. haydeni) and an
outgroup, the pygmy shrew (S. hoyi). Each specimen also possessed an
adjacent 76-bp imperfect copy of the tandem repeats. One individual was
heteroplasmic for length variants consisting of five and seven copies of
the 79-bp tandem repeat. The sequence of the repeats is conducive to the
formation of secondary structure. A termination-associated sequence is
present in each of the repeats and in a unique sequence region 5' to the
tandem array as well. Mean genetic distance between the masked shrew taxa
and the pygmy shrew was calculated separately for the unique sequence
region, one of the tandem repeats, the imperfect repeat, and these three
regions combined. The unique sequence region evolved more rapidly than the
tandem repeats or the imperfect repeat. The small genetic distance between
pairs of tandem repeats within an individual is consistent with a model of
concerted evolution. Repeats are apparently duplicated and lost at a high
rate, which tends to homogenize the tandem array. The rate of D- loop
sequence divergence between the masked and pygmy shrews is estimated to be
15%-20%/Myr, the highest rate observed in D-loops of mammals. Rapid
sequence evolution in shrews may be due either to their high metabolic rate
and short generation time or to the presence of variable numbers of tandem
repeats.
相似文献
80.
Selection of antibiotic-resistant mutants with enhanced isoamylase activity in Pseudomonas amyloderamosa 总被引:3,自引:0,他引:3
Dong-Her Wu Chiou-Yen Wen Wen-Shen Chu Long-Liu Lin Wen-Hwei Hsu 《Biotechnology letters》1993,15(9):883-888
Summary Isoamylase-hyperproducing strains of Pseudomonas amyloderamosa were bred by mutagenesis with UV light and N-methyl-N-nitro-N-nitrosoguanidine (NTG). The selection criterion for such strains was based on the formation of large turbid zones around the bacterial colonies in agar medium containing antibiotics and 1% waxy corn starch. Mutant WN6410 was obtained by treating P. amyloderamosa JD210 with five cycles of 1 × 104 J UV light and one cycle of NTG. P. amyloderamosa WN6410 had 22-fold increase in isoamylase activity when compared to wild-type strain SB15 and the maximal enzyme activity, 5,100 U/ml, could be achieved within 48 h in 2.5 L fed-batch fermentation. 相似文献