全文获取类型
| 收费全文 | 2727篇 |
| 免费 | 240篇 |
| 国内免费 | 252篇 |
专业分类
| 化学 | 294篇 |
| 晶体学 | 10篇 |
| 力学 | 127篇 |
| 综合类 | 42篇 |
| 数学 | 930篇 |
| 物理学 | 561篇 |
| 综合类 | 1255篇 |
出版年
| 2024年 | 17篇 |
| 2023年 | 30篇 |
| 2022年 | 40篇 |
| 2021年 | 49篇 |
| 2020年 | 79篇 |
| 2019年 | 60篇 |
| 2018年 | 65篇 |
| 2017年 | 69篇 |
| 2016年 | 77篇 |
| 2015年 | 70篇 |
| 2014年 | 110篇 |
| 2013年 | 136篇 |
| 2012年 | 132篇 |
| 2011年 | 140篇 |
| 2010年 | 109篇 |
| 2009年 | 118篇 |
| 2008年 | 138篇 |
| 2007年 | 151篇 |
| 2006年 | 165篇 |
| 2005年 | 168篇 |
| 2004年 | 126篇 |
| 2003年 | 121篇 |
| 2002年 | 132篇 |
| 2001年 | 104篇 |
| 2000年 | 118篇 |
| 1999年 | 99篇 |
| 1998年 | 84篇 |
| 1997年 | 75篇 |
| 1996年 | 77篇 |
| 1995年 | 48篇 |
| 1994年 | 64篇 |
| 1993年 | 40篇 |
| 1992年 | 26篇 |
| 1991年 | 24篇 |
| 1990年 | 17篇 |
| 1989年 | 16篇 |
| 1988年 | 18篇 |
| 1987年 | 16篇 |
| 1986年 | 12篇 |
| 1985年 | 9篇 |
| 1984年 | 11篇 |
| 1983年 | 9篇 |
| 1982年 | 14篇 |
| 1981年 | 5篇 |
| 1979年 | 9篇 |
| 1978年 | 4篇 |
| 1977年 | 4篇 |
| 1976年 | 3篇 |
| 1974年 | 2篇 |
| 1973年 | 2篇 |
排序方式： 共有3219条查询结果，搜索用时 93 毫秒
71.
An example in Ref. 1 is corrected to show that indeed a strongly pseudoconvex function, which is only once but not twice differentiable, does not necessarily have a strongly pseudoconvex gradient. 相似文献
72.
T. Szeredi 《Journal of statistical physics》1996,83(1-2):259-274
We present a study of a series of eigenstates occurring in the wedge billiard which may be quantized about tori by sejiclassical adiabatic quantization, even though the underlying classical system exhibits hard chaos and strictly possesses no tori. We also show that adiabatic eigenstates should be common in many chaotic systems, especially among the lower eigenstates, and present a heuristic argument as to why this should be so. 相似文献
73.
We found an approximate simple solution of sea-quark evolution equation in terms ofρ(=√ln(x
0/x)/ln[ln(Q
2/Λ2)/(Q
0
2
/Λ2)]) andζ(≡ln[ln(Q
2Λ2)/ln(Q
0
2
/Λ2)]) in the small-x region whenρ is fixed and compared with HERA data. Agreement with data is found for largeQ
2 and smallρ. Comparison with double asymptotic scaling prediction is made. We found a critical value ofρ. More data are needed to confirm this point. 相似文献
74.
Jinbo Wei ;Qinqin Yu 《Discrete and continuous dynamical systems》2024,29(7):2903-2927
In this paper, we consider a binary-ternary Boltzmann equation with hard spheres, which describes the elastic instantaneous interactions of both two particles and three particles. By using Kaniel-Shinbrot iteration, we prove the global existence and uniqueness of mild solution near vacuum in an integrable space, in which the functions are exponentially weighted $ L^{infty} $ for spatial variables and polynomial weighted $ L^1 $ for velocity variables. This result generalises the solution's space in the well-posedness theorem with respect to [Ann. Inst. H. Poincare Anal. Non Lineaire 39(2022), no.2,327-369], which deals with bounded solutions with exponential decay in the spatial-velocity variables. 相似文献
75.
Rong Sun Prof. Xudong Zhang Kwan San Hui Keliang Zhang Dr. Guogang Xu Changgang Li Dr. Jingyun Ma Prof. Wen He 《ChemElectroChem》2020,7(7):1598-1609
The well-matched technology of cathode and anode in Na-ion full batteries is highly challenging yet critically important in practical applications. Here, the high-performance Na-ion full batteries are developed by using NaTi2(PO4)3/N-doped mesoporous hard carbon hybrid anode and porous Na3V2(PO4)3 cathode. The different anodes are designed for well-matched Na-ion full batteries. The unique sandwich and mesoporous structural features endow the hybrid anode with a high reversible capacity (240 mAh g−1 at 1 C), high rate performance (109.7 mAh g−1 at 100 C), ultrahigh energy/power densities (76.56 Wh kg−1/5104 W kg−1) and a long cycle-life (capacity retention of 92.1 % after 1000 cycles at 100 C) in a half cell. In a full battery this hybrid anode can also deliver a higher capacitive contribution (79.5–87.7 %) and high energy/power densities (104 Wh kg−1/5256 W kg−1). This design provides a promising pathway for developing high performance and low-cost Na-ion full batteries. 相似文献
76.
The estimated global hard cider market is over $10 billion. Methods for determining their sugar content would have important implications in their quality assurance and nutritional values. In this study, the concentrations of fructose, glucose, and sucrose were determined in commercial hard cider and apple juice samples by hydrophilic interaction liquid chromatography with tandem mass spectrometry. The optimized sample preparation method consisted of sonication, a 1:10 dilution to 70:30 acetonitrile:water, centrifugation, filtration, and an additional 1:100 dilution to a final solvent composition of 80:20 acetonitrile:water. This method was validated with respect to selectivity, linearity, limit of detection, limit of quantitation, accuracy, and precision. Limits of detection and quantitation ranged from 0.01 to 0.1 and 0.05 to 0.5 mg/L, respectively, and linear ranges spanned at least a factor of 500 with excellent linearities (R2 > 0.999). Accuracy ranged from 81.7 to 107%. The relative standard deviations for all measurements were <7%. The method was applied to 11 different cider samples, one apple ale sample, and three different apple juice samples. Among the cider samples, a correlation between the fructose and glucose concentrations was found (R2 = 0.81). 相似文献
77.
研究和分析了蜗杆式振动珩齿时,被珩齿轮齿面上的珩磨啮合轨迹,以及在不同珩磨运动参数下,齿面上珩磨啮合纹路的形式。 相似文献
78.
一种本体协同冲突的检测方法 总被引：1，自引：0，他引：1
针对农业领域分布式的迭代知识协同建构过程中存在的协同冲突及难于检测的问题,提出协同冲突划分、检测与消解方法.把协同冲突与本体一致性问题区别开来,按本体知识编辑操作的影响范围、操作类型及启发式规则把协同冲突划分为硬冲突、软冲突.依据这个划分,给出一个高效的检测算法和冲突消解方案. 相似文献
79.
实验研究了非压缩状态下第二类哑铃畴（ⅡＤ）畴壁中垂直布洛赫线（ＶＢＬ）的温度稳定性，发现了与材料参量有关的两个重要温度（Ｔ）（ⅡＤ）与（Ｔ０）（ⅡＤ）当温度达到（Ｔ ）（ⅡＤ）时，ⅡＤ畴壁中的ＶＢＬ开始丢失；当温度达到（Ｔ０）（ⅡＤ）时，所有ⅡＤ畴壁中的ＶＢＬ链全部解体。在（Ｔ ）（ⅡＤ）与（Ｔ０）（ⅡＤ）之间，温度越高，ⅡＤ畴壁中丢失的ＶＢＬ数目越多。 相似文献
80.
本文进一步研究了由第一作者引入和研究的一类广义强非线性拟变分不等式和拟补问题．在另一类假设条件下证明了解的存在性，提出了一类新的求近似解的迭代算法——扰动算法，证明了扰动近似解序列强收敛于精确解 相似文献