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1.
Nuclear DNA content of some important plant species   总被引:59,自引:0,他引:59  
Nuclear DNA contents of more than 100 important plant species were measured by flow cytometry of isolated nuclei stained with propidium iodide.Arabidopsis exhibits developmentally regulated multiploidy and has a 2C nuclear DNA content of 0.30 pg (145 Mbp/1C), twice the value usually cited. The 2C value for rice is only about three times that ofArabidopsis. Tomato has a 2C value of about 2.0 pg, larger than commonly cited. This survey identified several horticultural crops in a variety of families with genomes only two or three times as large asArabidopsis; these include several fruit trees (a pricot, cherry, mango, orange, papaya, and peach). The small genome sizes of rice and the horticultural plants should facilitate molecular studies of these crops.  相似文献
2.
Location and phenotype of human adult keratinocyte stem cells of the skin   总被引:32,自引:0,他引:32  
The location and identity of interfollicular epidermal stem cells of adult human skin remain undefined. Based on our previous work in both adult murine and neonatal human foreskin, we demonstrate that cell surface levels of the alpha6 integrin and the transferrin receptor (CD71) are valid markers for resolving a putative stem cell, transit amplifying and differentiating compartment in adult human skin by flow cytometry. Specifically, epidermal cells expressing high levels of alpha6 integrin and low levels of the transferrin receptor CD71 (phenotype alpha6 (bri)CD71(dim)) exhibit several stem cell characteristics, comprising a minor population (2%-5%) of the K14(bri) fraction, enriched for quiescent and small blast-like cells with high clonogenic capacity, lacking the differentiation marker K10. Conversely, the majority of K14(bri) K10(neg) epidermal cells express high levels of CD71 (phenotype alpha6 (bri)CD71(bri)), and represent the actively cycling fraction of keratinocytes displaying greater cell size due to an increase in cytoplasmic area, consistent with their being transient amplifying cells. The alpha6 (bri)CD71(bri) population exhibited intermediate clonogenic capacity. A third population of K14(dim) but K10 positive epidermal cells could be identified by their low levels of alpha6 integrin expression (i.e. alpha6 (dim) cells), representing the differentiation compartment; predictably, this subpopulation exhibited poor clonogenic efficiency. Flow cytometric analysis for the hair follicle bulge region (stem cell) marker K15 revealed preferential expression of this keratin in alpha6 (bri) cells (i.e., both stem and transient amplifying fractions), but not the alpha6 (dim) population. Given that K15 positive cells could only be detected in the deep rete ridges of adult skin in situ, we conclude that stem and transient amplifying cells reside in this location, while differentiating (K15 negative) cells are found in the shallow rete ridges.  相似文献
3.
Current and future applications of flow cytometry in aquatic microbiology   总被引:26,自引:0,他引:26  
Flow cytometry has become a valuable tool in aquatic and environmental microbiology that combines direct and rapid assays to determine numbers, cell size distribution and additional biochemical and physiological characteristics of individual cells, revealing the heterogeneity present in a population or community. Flow cytometry exhibits three unique technical properties of high potential to study the microbiology of aquatic systems: (i) its tremendous velocity to obtain and process data; (ii) the sorting capacity of some cytometers, which allows the transfer of specific populations or even single cells to a determined location, thus allowing further physical, chemical, biological or molecular analysis; and (iii) high-speed multiparametric data acquisition and multivariate data analysis. Flow cytometry is now commonly used in aquatic microbiology, although the application of cell sorting to microbial ecology and quantification of heterotrophic nanoflagellates and viruses is still under development. The recent development of laser scanning cytometry also provides a new way to further analyse sorted cells or cells recovered on filter membranes or slides. The main infrastructure limitations of flow cytometry are: cost, need for skilled and well-trained operators, and adequate refrigeration systems for high-powered lasers and cell sorters. The selection and obtaining of the optimal fluorochromes, control microorganisms and validations for a specific application may sometimes be difficult to accomplish.  相似文献
4.
利用流式细胞光度术鉴定苹果倍性的研究   总被引:24,自引:2,他引:22  
利用流式细胞光度术测定了苹果12个二倍体,5个三倍体细胞DNA含量。结果表明:二倍体细胞核DNA含量平均为2.27pg,三倍体细胞核DNA含量平均为3.13pg。  相似文献
5.
Estimation of nuclear DNA content of plants by flow cytometry   总被引:23,自引:0,他引:23  
A rapid and simple protocol for estimation of nuclear DNA content of plants is described. Suspensions of intact nuclei are prepared either by chopping plant tissues or lysing protoplasts in a MgSO4 buffer, mixed with DNA standards, and stained with propidium iodide in a solution containing DNAase-free RNAase. Fluorescence intensities of the stained nuclei are measured by a flow cytometer. Values for nuclear DNA content are estimated by comparing fluorescence intensities of the nuclei of the test population with those of appropriate internal DNA standards. The same procedure can also be used for rapid determination of ploidy in plant tissues.  相似文献
6.
Loading red blood cells with trehalose: a step towards biostabilization   总被引:22,自引:0,他引:22  
A method for freeze-drying red blood cells (RBCs) while maintaining a high degree of viability has important implications in blood transfusion and clinical medicine. The disaccharide trehalose, found in animals capable of surviving dehydration can aid in this process. As a first step toward RBC preservation, we present a method for loading RBCs with trehalose. The method is based on the thermal properties of the RBC plasma membranes and provides efficient uptake of the sugar at 37 degrees C in a time span of 7 h. The data show that RBCs can be loaded with trehalose from the extracellular medium through a combination of osmotic imbalance and the phospholipid phase transition, resulting in intracellular trehalose concentrations of about 40 mM. During the loading period, the levels of ATP and 2,3-DPG are maintained close to the levels of fresh RBCs. Increasing the membrane fluidity through the use of a benzyl alcohol results in a higher concentration of intracellular trehalose, suggesting the importance of the membrane physical state for the uptake of the sugar. Osmotic fragility data show that trehalose exerts osmotic protection on RBCs. Flow cytometry data demonstrate that incubation of RBCs in a hypertonic trehalose solution results in a fraction of cells with different complexity and that it can be removed by washing and resuspending the RBCs in an iso-osmotic medium. The data provide an important first step in long-term preservation of RBCs.  相似文献
7.
以THP 1巨噬细胞源性泡沫细胞为研究对象 ,观察油酸对THP 1巨噬细胞源性泡沫细胞胆固醇流出和三磷酸腺苷结合盒转运体A1(ABCA1)表达的影响 ,以探讨油酸对动脉粥样硬化发生发展的影响。用液体闪烁计数器检测细胞内胆固醇流出 ,高效液相色谱分析细胞内总胆固醇、游离胆固醇和胆固醇酯含量 ,运用逆转录多聚酶链反应和Western印迹分别检测ABCA1mRNA与ABCA1蛋白的表达 ,采用流式细胞术检测细胞平均ABCA1荧光强度。实验显示油酸引起THP 1巨噬细胞源性泡沫细胞总胆固醇、游离胆固醇与胆固醇酯呈时间依赖性增加 ,而ABCA1蛋白水平、细胞平均ABCA1荧光强度以及apoA I介导的胆固醇流出呈时间依赖性减少 ,细胞内胆固醇增多 ,但ABCA1mRNA没有明显变化。结果表明 ,油酸减少THP 1巨噬细胞源性泡沫细胞ABCA1蛋白水平 ,降低细胞内胆固醇流出 ,增加细胞内胆固醇聚积。  相似文献
8.
Investigation of events committing cells to death revealed that a concealed NH2-terminal epitope of the pro-apoptotic protein Bak became exposed in vivo before apoptosis. This occurred after treatment of human Jurkat or CEM-C7A T-lymphoma cells with the mechanistically disparate agents staurosporine, etoposide or dexamethasone. The rapid, up to 10-fold increase in Bak-associated immunofluorescence was measured with epitope-specific monoclonal antibodies using flow cytometry and microscopy. In contrast, using a polyclonal antibody to Bak, immunofluorescence was detected both before and after treatment. There were no differences in Bak protein content nor in subcellular location before or after treatment. Immunofluorescence showed Bcl-xL and Bak were largely associated with mitochondria and in untreated cells they coimmunoprecipitated in the presence of nonioinic detergent. This association was significantly decreased after cell perturbation suggesting that Bcl-xL dissociation from Bak occurred on exposure of Bak's NH2 terminus. Multiple forms of Bak protein were observed by two dimensional electrophoresis but these were unchanged by inducers of apoptosis. This indicated that integration of cellular damage signals did not take place directly on the Bak protein. Release of proteins, including Bcl-xL, from Bak is suggested to be an important event in commitment to death.  相似文献
9.
流式细胞仪在生物学中的应用   总被引:18,自引:0,他引:18  
耿慧霞  王来  王强 《生物学杂志》2005,22(4):44-45,51
简要论述了流式细胞仪(flow cytometry,FCM)的工作原理,并对其在生物学基础科学研究中的应用进行阐述,包括对细胞凋亡、细胞周期、免疫细胞、细胞受体的研究应用。  相似文献
10.
以THP-1巨噬细胞源性泡沫细胞为研究对象,观察干扰素-γ(IFN-γ)对THP-1巨噬细胞源性泡沫细胞胆固醇流出和三磷酸腺苷结合盒转运体A1(ABCA1)表达的影响.以便探讨IFN-γ在动脉粥样硬化发生发展中的作用.采用液体闪烁计数器检测细胞内胆固醇流出, 高效液相色谱分析细胞内总胆固醇、游离胆固醇和胆固醇酯含量.运用逆转录-多聚酶链反应和蛋白质印迹分别检测ABCA1 mRNA与ABCA1蛋白质的表达, 采用流式细胞术检测细胞平均ABCA1荧光强度.发现IFN-γ引起THP-1巨噬细胞源性泡沫细胞总胆固醇、游离胆固醇与胆固醇酯呈时间依赖性增加, 而ABCA1 mRNA和蛋白质表达、细胞平均ABCA1荧光强度以及apoA-1介导的胆固醇流出呈时间依赖性减少, 细胞内胆固醇增多.结果表明IFN-γ抑制THP-1巨噬细胞源性泡沫细胞ABCA1表达及细胞内胆固醇流出,同时增加细胞内胆固醇聚积.  相似文献
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