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991.
Differentiation of embryonic stem cell (ESC)-derived embryoid bodies (EBs) is a heterogeneous process. ESCs can differentiate
in vitro into different cell types including beating cardiomyocytes. The main aim of the present study was to develop an improved
preparation method for scanning electron microscopic study of ESC-derived cardiac bundles and to investigate the fine structural
characteristics of mouse ESCs-derived cardiomyocytes using electron microscopy. The mouse ESCs differentiation was induced
by EBs’ development through hanging drop, suspension and plating stages. Cardiomyocytes appeared in the EBs’ outgrowth as
beating clusters that grew in size and formed thick branching bundles gradually. Cardiac bundles showed cross striation even
when they were observed under an inverted microscope. They showed a positive immunostaining for cardiac troponin I and α-actinin.
Transmission and scanning electron microscopy (TEM & SEM) were used to study the structural characteristics of ESC-derived
cardiomyocytes. Three weeks after plating, differentiated EBs showed a superficial layer of compact fibrous ECM that made
detailed observation of cardiac bundles impossible. We tried several preparation methods to remove unwanted cells and fibers,
and finally we revealed the branching bundles of cardiomyocytes. In TEM study, most cardiomyocytes showed parallel arrays
of myofibrils with a mature sarcomeric organization marked by H-bands, M-lines and numerous T-tubules. Cardiomyocytes were
connected to each other by intercalated discs composed of numerous gap junctions and fascia adherences. 相似文献
992.
993.
Hen egg white lysozyme was immobilized by carbodiimide method to form amide bonds with a polymer (AS-L) showing reversibly soluble-insoluble characteristics with pH change. The immobilized enzyme (LY-AS) was soluble above pH 6 and precipitate below pH 4.5, offering advantages in that it can carry out hydrolysis of microbial cells in a soluble form yet be recovered after precipitation at low pH. The maximum specific activity of LY-AS was 66% of that of free lysozyme with M. lysodeikticus cells as substrate, which is much higher than the values reported in the literature using water-insoluble materials as carriers. The effects of pH and temperature on the activity of LY-AS were studied and compared with those of free lysozyme. With repeated pH cycles between 6.6 and 4.5, the operation half-life of immobilized enzyme activity was nine cycles. Repeated batch lysis of microbial cells could be carried out with intermittent enzyme precipitation and recovery steps. In such an operation the insoluble residual cells should be recovered together with the immobilized enzyme to minimize enzyme loss arising from adsorption to cells. 相似文献
994.
初产母猪断奶后能否正常发情对养猪生产影响重大,也是初产母猪被淘汰的主要原因。本研究以乏情和发情初产母猪为研究对象,首次利用RNA-seq技术对其下丘脑-垂体-卵巢轴中的基因间长链非编码RNAs(long intergenic noncoding RNAs,lincRNAs)进行筛选比较,得到lincRNAs的表达图谱,并对其特征和功能进行了初步分析。结果显示,在乏情和发情初产母猪下丘脑–垂体–卵巢轴中鉴定得到3519个lincRNAs,以发情组为对照共有17个lincRNAs存在差异表达,其中12个表达上调,5个表达下调(FC≥2,P<0.05)。选择4个差异表达的lincRNAs经qRT-PCR验证,其表达水平与测序结果基本一致。对这17个差异表达的lincRNAs进行GO分析、KEGG通路分析及lincRNA-mRNA共表达网络分析,发现这些lincRNAs主要与猪卵母细胞减数分裂成熟、卵巢细胞分化及颗粒细胞凋亡等生殖活动相关。本研究结果丰富了猪lincRNAs数据资源,为进一步深入研究初产母猪的生殖机能提供了理论依据。 相似文献
995.
Marine bacteria have recently attracted attention as potentially useful candidates for the production of practical materials
from marine ecosystems, including the oceanic carbon dioxide cycle. The advantages of using marine bacteria for the biosynthesis
of poly(hydroxyalkanoate) (PHA), one of the eco-friendly bioplastics, include avoiding contamination with bacteria that lack
salt-water resistance, ability to use filtered seawater as a culture medium, and the potential for extracellular production
of PHA, all of which would contribute to large-scale industrial production of PHA. A novel marine bacterium, Vibrio sp. strain KN01, was isolated and characterized in PHA productivity using various carbon sources under aerobic and aerobic–anaerobic
marine conditions. The PHA contents of all the samples under the aerobic–anaerobic condition, especially when using soybean
oil as the sole carbon source, were enhanced by limiting the amount of dissolved oxygen. The PHA accumulated using soybean
oil as a sole carbon source under the aerobic–anaerobic condition contained 14% 3-hydroxypropionate (3HP) and 3% 5-hydroxyvalerate
(5HV) units in addition to (R)-3-hydroxybutyrate (3HB) units and had a molecular weight of 42 × 103 g/mol. The present result indicates that the activity of the beta-oxidation pathway under the aerobic–anaerobic condition
is reduced due to a reduction in the amount of dissolved oxygen. These findings have potential for use in controlling the
biosynthesis of long main-chain PHA by regulating the activity of the beta-oxidation pathway, which also could be regulated
by varying the dissolved oxygen concentration. 相似文献
996.
从酵母中提取谷胱甘肽的初步研究 总被引:28,自引:3,他引:28
考察了不同提取方法对从酵母中提取谷胱甘肽(GSH)的影响,热水抽提由于其提取收率高(90%),耗时短(10min)经济性强而明显优于其它提取方法,对732阳离子交换树脂纯化GSH进行了初步研究,主要研究了树脂颗粒大小对提纯GSH的影响,采用60~80目的树脂,GSH收率为57.6%,虽然比80目以上的树脂低10%但前者操作作所需时间只有后者的1/3。 相似文献
997.
重组HIV表面抗原gp120的表达纯化及免疫学鉴定 总被引:4,自引:0,他引:4
为研制具有流行特点的HIV血清学诊断试剂,采用pET系统表达HIV-1表面糖蛋白gp120。研究发现,全长的gp120在E.coli中不能有效表达;N端半长的gp120可以表达,但表达量很低;仅保留N端1/3的gp120(包含gp120V1/V2抗原决定簇)有效表达,表达蛋白占菌体总蛋白的18%;Westernblot显示较好的反应原性;通过金属螯合层析,产物得到完全纯化。在这些结果的基础上,我们表达了流行株的gp120片段,为探索gp120在大肠杆菌的高效表达,建立针对中国人群的HIV血清学诊断系统奠定基础。 相似文献
998.
We examined the relationship between body size of the riparian spider Nephila clavata and the contribution of allochthonous (aquatic insects) and autochthonous (terrestrial insects) sources to its diet using
stable isotope analysis. During the study period from July to September, the body size of the females increased remarkably
(about 60-fold) but that of males remained small. The biomass of both aquatic and terrestrial insects trapped on the spider
webs increased with spider size, with the biomass of the former ranging between 30 and 70% of that of the terrestrial insects.
The average relative contribution of aquatic insects to the diet of the spiders, calculated from δ13C values, was 40–50% in spiders in the early juvenile and juvenile stages, 35% in adult males and 4% in adult females. There
was a significant negative relationship between the relative contribution of aquatic insects and body size of the female spiders.
We conclude that aquatic insects might be an important seasonal dietary subsidy for small spiders and that these allochthonous
subsidies may facilitate the growth of riparian spiders, which may in turn enable the spiders to feed on larger prey. 相似文献
999.
SuiKang Wang YouHuang Bai ChenJia Shen YunRong Wu SaiNa Zhang DeAn Jiang Tom J. Guilfoyle Ming Chen YanHua Qi 《Functional & integrative genomics》2010,10(4):533-546
Sorghum, a C4 model plant, has been studied to develop an understanding of the molecular mechanism of resistance to stress.
The auxin-response genes, auxin/indole-3-acetic acid (Aux/IAA), auxin-response factor (ARF), Gretchen Hagen3 (GH3), small
auxin-up RNAs, and lateral organ boundaries (LBD), are involved in growth/development and stress/defense responses in Arabidopsis and rice, but they have not been studied in sorghum. In the present paper, the chromosome distribution, gene duplication,
promoters, intron/exon, and phylogenic relationships of Aux/IAA, ARF, GH3, and LBD genes in sorghum are presented. Furthermore,
real-time PCR analysis demonstrated these genes are differently expressed in leaf/root of sorghum and indicated the expression
profile of these gene families under IAA, brassinosteroid (BR), salt, and drought treatments. The SbGH3 and SbLBD genes, expressed
in low level under natural condition, were highly induced by salt and drought stress consistent with their products being
involved in both abiotic stresses. Three genes, SbIAA1, SbGH3-13, and SbLBD32, were highly induced under all the four treatments,
IAA, BR, salt, and drought. The analysis provided new evidence for role of auxin in stress response, implied there are cross
talk between auxin, BR and abiotic stress signaling pathways. 相似文献
1000.
Linda S. M. Ooi Wing-Shan Ho Karry L. K. Ngai Li Tian Paul K. S. Chan Samuel S. M. Sun Vincent E. C. Ooi 《Journal of biosciences》2010,35(1):95-103
A mannose-binding lectin (Narcissus tazetta lectin [NTL]) with potent antiviral activity was isolated and purified from the bulbs of the Chinese daffodil Narcissus tazetta var. chinensis, using ion exchange chromatography on diethylaminoethyl (DEAE)-cellulose, affinity chromatography on mannose-agarose and
fast protein liquid chromatography (FPLC)-gel filtration on Superose 12. The purified lectin was shown to have an apparent
molecular mass of 26 kDa by gel filtration and 13 kDa by SDS-PAGE, indicating that it is probably a dimer with two identical
subunits. The cDNA-derived amino acid sequence of NTL as determined by molecular cloning also reveals that NTL protein contains
a mature polypeptide consisting of 105 amino acids and a C-terminal peptide extension. Three-dimensional modelling study demonstrated
that the NTL primary polypeptide contains three subdomains, each with a conserved mannose-binding site. It shows a high homology
of about 60%–80% similarity with the existing monocot mannose-binding lectins. NTL could significantly inhibit plaque formation
by the human respiratory syncytial virus (RSV) with an IC50 of 2.30 μg/ml and exhibit strong antiviral properties against influenza A (H1N1, H3N2, H5N1) and influenza B viruses with
IC50 values ranging from 0.20 μg/ml to 1.33 μg/ml in a dose-dependent manner. It is worth noting that the modes of antiviral action
of NTL against RSV and influenza A virus are significantly different. NTL is effective in the inhibition of RSV during the
whole viral infection cycle, but the antiviral activity of NTL is mainly expressed at the early stage of the viral cycle of
influenza A (H1N1) virus. NTL with a high selective index (SI=CC50/IC50≥141) resulting from its potent antiviral activity and low cytotoxicity demonstrates a potential for biotechnological development
as an antiviral agent. 相似文献