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51.
Exact analysis of asymmetric random polling systems with single buffers and correlated input process
We introduce a simple approach for modeling and analyzing asymmetric random polling systems with single buffers and correlated input process. We consider two variations of single buffers system: the conventional system and the buffer relaxation system. In the conventional system, at most one customer may be resided in any queue at any time. In the buffer relaxation system, a buffer becomes available to new customers as soon as the current customer is being served. Previous studies concentrate on conventional single buffer system with independent Poisson process input process. It has been shown that the asymmetric system requires the solution ofm 2
m
–1) linear equations; and the symmetric system requires the solution of 2
m–1–1 linear equations, wherem is the number of stations in the system. For both the conventional system and the buffer relaxation system, we give the exact solution to the more general case and show that our analysis requires the solution of 2
m
–1 linear equations. For the symmetric case, we obtain explicit expressions for several performance measures of the system. These performance measures include the mean and second moment of the cycle time, loss probability, throughput, and the expected delay observed by a customer. 相似文献
52.
53.
This paper proposes an color image encryption algorithm using alternate chaotic mapping structure. Initially, we use the R, G and B components to form a matrix. Then one-dimension logistic and two-dimension logistic mapping is used to generate a chaotic matrix, then iterate two chaotic mappings alternately to permute the matrix. For every iteration, XOR operation is adopted to encrypt plain-image matrix, then make further transformation to diffuse the matrix. At last, the encrypted color image is obtained from the confused matrix. Theoretical analysis and experimental results has proved the cryptosystem is secure and practical, and it is suitable for encrypting color images. 相似文献
54.
Carina M. M. Machado Paula Gameiro Helena M. V. M. Soares 《Journal of solution chemistry》2008,37(5):603-617
The complexation behavior of eight M–(buffer)
x
–(OH)
y
systems involving two divalent ions (cobalt and nickel) and four zwitterionic biological buffers (AMPSO, DIPSO, TAPS and
TAPSO) were characterized. Complex formation was detected for all eight M–(buffer)
x
–(OH)
y
systems studied, but fully defined final models were obtained for only four of these systems. For systems involving cobalt
or nickel with AMPSO or TAPS, a complete characterization of the systems was not possible in the studied buffer pH-range.
Metal complexation was studied by glass-electrode potentiometry (GEP) and UV-Vis spectroscopy at 25.0 °C and I=0.1 mol⋅dm−3 KNO3 ionic strength. For the Ni–(L)
x
–(OH)
y
and Co–(L)
x
–(OH)
y
systems, with L = TAPSO or DIPSO, the proposed final models and overall stability constants were obtained by combining results
from both techniques. For the Ni–(L)
x
–(OH)
y
systems, the measured values of the stability constants are log 10
β
NiL=3.0±0.1 and log 10
β
NiL2=4.8±0.1 for L = TAPSO, and log 10
β
NiL=2.7±0.1 and log 10
β
NiL2=4.6±0.1 for L = DIPSO. For the Co–(L)
x
–(OH)
y
systems, the overall stability constants are log 10
β
CoL=2.2±0.1, log 10
β
CoL2=3.6±0.2 and log 10
β
CoL(OH)=7.6±0.1 for L = TAPSO, and log 10
β
CoL=2.0±0.1 and log 10
β
CoL(OH)=7.8±0.1 for L = DIPSO. For both buffers, the CoL(OH) species is characterized by a major structural rearrangement. 相似文献
55.
Xing B Jiang T Wu X Liew R Zhou J Zhang D Yeow EK 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(50):14170-14177
The molecular interactions of the glycopeptide antibiotic vancomycin (Van) with bacterial cell wall analogues N,N'-diacetyl-L-Lys-D-Ala-D-Ala (Ac(2) KdAdA) and N,N'-diacetyl-L-Lys-D-Ala-D-Lac (Ac(2) KdAdL) were investigated in neat water, phosphate buffer and HEPES buffer by using fluorescence correlation spectroscopy (FCS) and molecular dynamics (MD) simulations. The FCS determined dissociation constants (k(d)) show that the intrinsic binding affinity between Van and the drug-sensitive peptide ligand Ac(2)KdAdA remains invariant when the solvent is changed from neat water to either PBS or HEPES buffer; this demonstrates that there are no obvious solvent effects on the association between Van and Ac(2)KdAdA due to the strong intermolecular interaction between the two moieties. When compared to Ac(2)KdAdA, a significantly larger k(d) value was observed for the binding between the drug-resistant peptide ligand Ac(2)KdAdL and Van. Furthermore, the k(d) increased by about 8- to 11-times when the solvent was changed from neat water to 10 mM phosphate/HEPES buffer. The stability of the Ac(2)KdAdL-Van complex was dependent on the concentration of the buffer and k(d) increases as the concentration of either phosphate ions or HEPES increased until an equilibrium was attained. Both FCS and MD simulation studies clearly showed that the components constituting the buffer solution (e.g., phosphate ions and HEPES) are involved in molecular interactions with the binding pocket of Van and they profoundly affect the intrinsic stability of the complex formed between the low-affinity Ac(2)KdAdL and Van. These results could help us to better understand the detailed structure and activity of glycopeptide antibiotic derivatives toward bacterial cell wall peptide analogues, and can further facilitate the development of new drug candidates against drug-resistant bacterial strains. 相似文献
56.
57.
以人在球体上走动引起球体向前滚动为例,利用牛顿定律说明人-球系统中内力、外力与运动之间的关系.尽管阻碍球体滚动的地面摩擦是人-球系统向前运动的必要条件,且作为外力与系统动量变化率相等,但从运动的因果关系考察,人与球体之间的竖直作用力才是系统运动的真正动力. 相似文献
58.
近红外光谱预测稻谷水分含量特征谱区选择及其效率分析 总被引:1,自引:0,他引:1
对364份水分含量在2.24%~32.66%之间的“冈优916”稻谷样品,经均值中心化、一阶微分、标准归一化和多元散射校正等预处理后,采用分段间隔法、组合分段法、滑动窗口法和反向分段法等进行特征谱区选择,分别使用偏最小二乘法(PLS)和主成分回归(PCR)两种定量分析方法,获得稻谷含水量近红外光谱预测模型最佳的特征谱区。首次给出了分段间隔法、组合分段法、滑动窗口法和反向分段法等传统的特征谱区选择方法的计算复杂度的计算公式,并对比分析了这几种特征谱区选择方法的程序运行效率。结果表明:采用PLS建模对稻谷含水量光谱的预测性能优于PCR建模,但PLS建模的效率低于PCR建模;在PLS建模中,采用反向分段法对稻谷光谱含水量的预测性能最好,其预测集的相关系数RP为0.995 6,预测均方根偏差RMSEP为0.78%;其次是滑动窗口法,其RP为0.994 3,RMSEP为0.89%;但这两种特征谱区选择方法的程序运行效率较低,反向分段法的平均运行时间为4.87 h,滑动窗口法的平均运行时间为29.82 h。该研究结果为今后在并行计算或分布式计算上开发近红外光谱预测模型的快速算法提供参考。 相似文献
59.
工程项目施工现场废料分拣的效率对施工进度具有重要的影响。通过分析现场废料分拣实施过程,建立了带有限中间缓冲的混合流水车间调度模型。提出了收集阶段作业排序的动态自适应算法和后续设备分配问题的考虑缓冲区的设备分配规则,在此基础上设计了废料分拣模型的启发式算法,平衡各分区工作量,进一步搜索最优解,并推导了问题的一个低界。实验结果表明,所提出算法能很好地对施工现场废料分拣问题进行求解,具有良好的收敛性和较高的时间效率。 相似文献
60.
C. Wieczerkowski 《Journal of statistical physics》1997,89(5-6):929-945
We formulate a renormalized running coupling expansion for theΒ-function and the potential of the renormalized Φ4-trajectory on four-dimensional Euclidean space-time. Renormalization invariance is used as a first principle. No reference
is made to bare quantities. The expansion is proved to be finite to all orders of perturbation theory. The proof includes
a large-momentum bound on the connected free propagator amputated vertices. 相似文献