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101.
A computerized mechanical cell stimulator for tissue culture: Effects on skeletal muscle organogenesis 总被引:8,自引:0,他引:8
Herman H. Vandenburgh 《In vitro cellular & developmental biology. Plant》1988,24(7):609-619
Summary A tissue culture system has been developed which can mechanically stimulate cells growing on a highly elastic plastic substratum
in a 24-well cell growth chamber. The collagen-coated substratum to which the cells attach and grow in the Mechanical Cell
Stimulator (Model I) can be repetitively stretched and relaxed by stepper motor with linear accuracy of 30 μm. The activity
controlling unit is an Apple IIe computer interfaced with the cell growth chamber via optical data links and is capable of
simulating many of the mechanical activity patterns that cells are subjected to in vivo. Primary avian skeletal myoblasts
proliferate and fuse into multinucleated myotubes in this set-up in a manner similar to normal tissue culture dishes. Under
static culture conditions, the muscle cells differentiate into networks of myotubes which show little orientation. Growing
the proliferating muscle cells on a unidirectional stretching substratum causes the developing myotubes to orient parallel
to the direction of movement. In contrast, growing the cells on a substratum undergoing continuous stretch-relaxation cycling
orients the developing myotubes perpendicular to the direction of movement. Neither type of mechanical activity significantly
affects the rate of cell proliferation of the rate of myoblast fusion into myotubes. These results indicate that during in
vivo skeletal muscle organogenesis, when substantial mechanical stresses are placed on skeletal muscle cells by both continuous
bone elongation and by spontaneous contractions, only bone elongation plays a significant role in proper fiber orientation
for subsequent functional work.
Supported by grants NS16753, AR36266, and RR05818 from the National Institutes of Health, Bethesda, MD. 相似文献
102.
采后预处理使甜橙果皮含水量减少,改善理化性状,降低果实对低温的敏感性,从而控制了福斑病的发生,使发病率从61.7~66.0%降至4.7~6.7%。低温贮藏的呼吸强度和内源乙烯的生成也受到明显的抑制,但对果实的主要内含物和质量并无影响。控制褐斑病发生的适宜的预处理,是在10~15℃和85~90%相对湿度下处理7~10d,使果实重耗约2.5~4.0%。 相似文献
103.
P Mentré F Escaig 《Biology of the cell / under the auspices of the European Cell Biology Organization》1992,74(1):119-126
Flotation on hot water (about 60 degrees C) which is frequently employed to stretch semithin sections on substrates for SIMS (secondary ion mass spectrometry) microscopy, is the cause of numerous artefacts. In the case of epoxy resin-embedded tissue, one observes loss of potassium and sodium and accumulation of calcium. The relative contrast of cell nuclei in the ionic images, is rapidly affected by these ion migrations. After prolonged contact with hot water, tissue becomes uniformly emissive. In the case of hydrosoluble resin-embedded tissue, potassium and sodium do not appear to be affected by the action of water, which suggests that they are covalently bound with chelating sites buried beneath the layer of water bound to the surface of the macromolecules. Calcium accumulates, probably on widely exposed anionic sites. Moreover, the domains observed in hydrosoluble resin-embedded tissue shrink differently according to the proportion of water removed by melamine; this can provide interesting information on the initial equilibrium between water, ion sand macromolecules. Our results seem to support the assumption that bound water should play an important role in the preservation of both macromolecular architecture and ion distributions. 相似文献
104.
猴脑线粒体DNA提取及限制性内切酶分析 总被引:2,自引:0,他引:2
本文用冷碱法从2只恒河猴和1只食蟹猴的脑组织中提取mtDNA,最后的得率大约为0.7μgmtDNA/g脑组织,是肝脏组织得率的1/3左右。与肝脏组织相比较,从脑组织中提取mtDNA有以下优点:1.匀浆方便。2.样品中蛋白杂质少,容易彻底抽提去除蛋白质。3.大分子RNA杂质极少,不经Sepharose-4B柱或RNawe处理,就可得到较纯的样品。加之哺乳动物脑的体积较大,哺乳动物脑组织不失为提取mtDNA的一个有用的组织来源。经16种限制性内切酶分析,并与来自同一个体肝脏组织的mtDNA比较,结果进一步证实,mtDNA无组织特异性。对12岁以上老年猴脑mtDNA的分析表明,在衰老中,动物mtDNA的序列可能没有变化,甲基化程度也无显著增高。 相似文献
105.
Nitrosomonas europaea is capable of maintaining an anaerobic metabolism, using pyruvate as an electron donor and nitrite as an electron acceptor; utilization of nitrite depends upon supply of both pyruvate and ammonia. The role of ammonia in this reaction was not determined. N europaea also assimilates CO2 anaerobically into cell material in the presence of nitrite (0.5–1.0 mM), pyruvate and ammonia. This reaction was partially inhibited by nitrite which apparently competed with CO2 for reducing power. Anaerobic nitrite respiration is sensitive to ionophores, FCCP being the most effective.Non-standard-abbreviations TCA
trichloroacetic acid
- FCCP
carbonylcyanide-p-trifluoromethoxyphenylhydrazon 相似文献
106.
S. Delventhal A. Brandis H. Ostertag R. Pabst 《Virchows Archiv. B, Cell pathology including molecular pathology》1992,62(1):271-274
The relevance of bronchus-associated lymphoid tissue (BALT) in man is still under discussion. Animal experiments indicate
that the development of BALT is dependent on microbial stimulation. Therefore, the incidence of BALT was investigated retrospectively
in specimens removed during surgical procedures on patients with chronic pulmonary inflammation. All these patients had severe
chronic bronchitis and bronchiectasis, but BALT was found in only 8%. In patients with BALT and a malignant tumor, occlusion
of a bronchus with poststenotic pneumonia was always present and BALT was observed exclusively in areas peripheral to the
occlusion. In man other compartments of the lung must be responsible for the immune function of BALT found in animals.
Partly presented at the Congress of the Eur. Respir. Soc, 21.- 26.9.1991 in Brussels. (Abstract: Eur Respir J. 4, Suppl. 14:217p) 相似文献
107.
In an 18 year old Japanese larch stand, leaf characteristics such as area, weight, gross photosynthetic rate and respiration
rate were studied in order to obtain basic information on estimating canopy photosynthesis and respiration. The leaf growth
courses in area and weight from bud opening were approximated by simple logistic curves. The growth coefficient for the area
growth curve was 0.155–0.175 day−1, while that for the weight growth was 0.112–0.117 day−1. The larger growth coefficient in area growth caused the seasonal change in specific leaf area (SLA) that increased after bud opening to its peak early in May at almost 300 cm2 g−1 and then decreased until it leveled off at about 140 cm2g−1. The change inSLA indicates the possibility that leaf area growth precedes leaf thickness growth. The relationship between the coefficientsa andb of the gross photosynthetic rate (p)-light flux density (1) curve (p=bI/(1+aI)) and the mean relative light flux density (I′/I
0) at each canopy height were approximated by hyperbolic formulae:a=A/(I′/I
0)+B andb=C/(I′/I
0)+D. Leaf respiration rate was also increased with increasingI′/I
0. Seasonal change of gross photosynthetic rate and leaf respiration rate were related to mean air temperature through linear
regression on semilogarithmic co-ordinates. 相似文献
108.
The organotypic culture of human skin keratinocytes and fibroblasts to achieve form and function 总被引:6,自引:0,他引:6
Dr. Nancy L. Parenteau Patrick Bilbo Cynthia J. M. Nolte Valerie S. Mason Mireille Rosenberg 《Cytotechnology》1992,9(1-3):163-171
We describe an organotypic model of human skin comprised of a stratified layer of human epidermal keratinocytes and dermal
fibroblasts within a contracted collagen lattice. Feasible and reproducible production of the skin construct has required
the use of traditional as well as specialized culture techniques. The configuration of the construct has been engineered to
maintain polarity and permit extended culture at the air-liquid interface. Morphological, biochemical and kinetic parameters
were assessed and functional assays were performed to determine the degree of similarity to human skin. Light and ultrastructural
morphology of the epidermis closely resembled human skin. The immunocytochemical localization of a number of differentiation
markers and extracellular matrix proteins was also similar to human skin. Kinetic data showed a transition of the epidermal
layer to a morein vivo-like growth rate during the development of the construct at the air-liquid interface. The barrier properties of the construct
also increased with time reaching a permeability to water of less than 2%·h after approximately 2 weeks at the air-liquid
interface which is still on average 30-fold more water-permeable than normal human skin. The construct is currently used forin vitro research and testing and is also being tested in clinical applications. 相似文献
109.
110.
Hydrogen cyanide and embryonal dormancy in apple seeds 总被引:3,自引:0,他引:3
Embryos of apple ( Malus domestica Borh. cv. Antonówka) were treated with 1 m M gaseous HCN for 6 h and cultured under a 12 h photoperiod. HCN pretreatment stimulated germination, increased the length of hypocotyls, shortened the main root and decreased the percentages of seedlings with asymmetrically grown as well as with asymmetrically greened cotyledons. High activity of β-cyanoalanine synthase (EC 4.4.1.9) and a sharp increase in cyanogen content during embryo culture suggested very low levels of endogenous HCN. despite the activity of HCN releasing enzymes. The obtained data allow us to postulate an important role for cyanide in the regulatory complex controlling dormancy in apple seeds. Experiments with respiratory inhibitors indicated, however, that HCN pretreatment affected neither the alternative electron transport pathway nor residual respiration. 相似文献