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排序方式: 共有6165条查询结果,搜索用时 15 毫秒
951.
Jun Feng YanLin Ye Biao Yang ChengJian Lin HuiMin Jia DanYang Pang ZhiHuan Li JianLing Lou QiTe Li XiaoFei Yang Jing Li HongLiang Zang Qiang Liu Wei Jiang ChenGuang Li Yang Liu ZhiQiang Chen HongYi Wu ChunGuang Wang Wei Liu Xiang Wang JingJing Li DiWen Luo Ying Jiang ShiWei Bai JinYan Xu NanRu Ma LiJie Sun DongXi Wang 《中国科学:物理学 力学 天文学(英文版)》2019,(1)
The inelastic excitations and cluster decay of ~(13)C have been measured using the reaction,9Be(~(13)C, ~(13)C* →~9Be + α)~9Be. We observe strong excitation to the 14.3-MeV(1/2-) resonant state from the cluster-decay channel, leading to an enhanced monopole matrix element of(6.3 ± 0.6) fm~2. This large cluster-related monopole strength is a clear indication of the cluster-structure domination of this state and is consistent with the recent prediction of the orthogonality condition model(OCM). It would be interesting to further explore the three-center molecular rotational band that is initiated from the observed band-head. 相似文献
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953.
内埋武器高速风洞弹射投放模型试验关键技术研究 总被引:7,自引:1,他引:6
针对新一代战斗机超声速内埋武器弹射投放分离安全性问题,采用高速风洞投放实验技术研究内埋武器从开式武器舱弹射投放分离动态运动过程,风洞投放模型试验过程中采用除垂直加速度不足外,其余全部运动严格相似的轻模型相似设计方法,并针对轻模型法垂直加速度不足所导致的投放垂直位移偏离实物位移问题,采用一种简单易行的公式修正法进行补偿,试验给出了不同初始弹射投放分离条件下,内埋武器从载机投放分离后运动轨迹与姿态角随分离时间的变化规律,试验马赫数$Ma = 1.5$.研究结果表明:初始投放分离角速度对内埋武器投放分离后的运动轨迹及姿态角有较大的影响,当初始投放分离角速度$\omega _{z0}^s = 0^\circ/{\rm s}$时,内埋导弹出舱后先向下运动远离载机的流场干扰区,之后逐渐向载机方向抬升靠近并最终碰撞载机,高速风洞投放试验结果是不安全的,但经过公式修正后投放试验结果比较乐观,垂直方向运动仍然一直下降远离载机,这说明采用高速风洞投放试验得出的导弹不安全投放分离对真实载机来说不一定会出现,高速风洞投放试验结果比较保守. 当初始投放分离角速度$\omega _{z0}^s= 15^\circ/{\rm s}$和$\omega _{z0}^s = 30^\circ/{\rm s}$时,内埋导弹投放分离后运动趋势几乎一致, 均没出现向载机靠近的现象,内埋导弹具有一定的初始投放分离角速度有利于内埋武器的安全分离. 相似文献
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956.
The strength and equation of state of molybdenum triboride have been determined under nonhydrostatic compression up to 80?GPa, using an angle-dispersive radial X-ray diffraction technique in a diamond anvil cell (DAC). The RXD data yield a bulk modulus and its pressure derivative as K0?=?342(6)?GPa with K0′?=?2.11(17) at ψ?=?54.7°. Analysis of diffraction data using the strain theory indicates that the ratio of differential stress to shear modulus (t/G) ranges from 0.002 to 0.050 at pressures of 4–80?GPa. Together with theoretical results on the high pressure shear modulus, our results here show that molybdenum triboride sample under uniaxial compression can support a differential stress of ~10?GPa when it started to yield with plastic deformation at ~30?GPa. In addition, we draw a conclusion that MoB3 is not a superhard material but a hard material. 相似文献
957.
Renal Clearable Luminescent WSe2 for Radioprotection of Nontargeted Tissues during Radiotherapy
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Haixia Liu Junying Wang Yaqi Jing Jiang Yang Xueting Bai Xiaoyu Mu Fujuan Xu Xuhui Xue Lingfang Liu Yuan‐Ming Sun Qiang Liu Haitao Dai Changlong Liu Xiao‐Dong Zhang 《Particle & Particle Systems Characterization》2017,34(6)
High‐energy ionizing radiation is widely used in medical diagnosis and cancer radiation therapy. However, high‐energy radiation can also impose significant damages in healthy tissues during medical treatments via direct DNA damages and indirect damages from production of reactive oxygen species (ROS). Therefore, it is urgent to develop highly effective radioprotectants with low toxicities that can meet the increasing needs for alleviating the adverse effects from cancer radiation therapy and nuclear emergency. In this work, strongly catalytic ultrasmall (sub‐5 nm) cysteine‐protected WSe2 dots are employed to protect healthy tissues against radiation via diminishing radiation‐induced free radicals. The WSe2 dots with high surface activities can recover radiation‐induced DNA damages and eliminate the excessive ROS generated from radiation. In vivo experiments confirm that the survival rate of mice treated with WSe2 dots is significantly elevated with radiation damages postponed under exposure to high‐dose ionizing radiation. Furthermore, the free radicals in major organs and hematological system can be appreciably omitted, suggesting their unique role as free radical scavengers. These WSe2 dots in ultrasmall size show rapid renal clearance of ≈74% injection dose via urine excretion in 24 h and do not cause any apparent toxicity in vivo for up to 30 d. 相似文献
958.
The paper proposes a catadioptric infrared dual band optical system based on catadioptric configuration and optically passive athermal design method. The system shares primary mirror, secondary mirror and collimating lens group, and achieves abruption in longwave infrared and midwave infrared using a dichroic beam splitter. The influence of temperature on optical parameters, the design theory and design method are analyzed. A design example is presented. The detailed optimization design method and some considering factors in engineering design moment are discussed. The design results illustrate that the system can obtain good image quality in environment temperature of 10–40?°C, which could satisfy the design requirement. The actual test result not only satisfies the design requirement, but also validates the availability of the method in the paper. 相似文献
959.
For any given matrix $A∈\mathbb{C}^{n×n}$, a preconditioner $t_U(A)$ called the superoptimal preconditioner was proposed in 1992 by Tyrtyshnikov. It has been shown that $t_U(A)$ is an efficient preconditioner for solving various structured systems, for instance, Toeplitz-like systems. In this paper, we construct the superoptimal preconditioners for different functions of matrices. Let $f$ be a function of matrices from$\mathbb{C}^{n×n}$ to$\mathbb{C}^{n×n}$. For any $A∈\mathbb{C}^{n×n}$, one may construct two superoptimal preconditioners for $f(A)$: $t_U(f(A))$ and $f(t_U(A))$. We establish basic properties of $t_U(f(A))$) and $f(t_U(A))$ for different functions of matrices. Some numerical tests demonstrate that the proposed preconditioners are very efficient for solving the system $f(A)x=b$. 相似文献
960.
利用直接沉积法在多孔阳极氧化铝(AAO)材料表面沉积CuCl22H2O水溶液制备纳米花状薄膜,并利用场发射扫描电镜对其形貌进行表征,结合X射线光电子能谱等技术鉴定其成分,结果表明纳米花状薄膜为CuCl2。在室温条件下,测量了样品的光致发光光谱特性,观察到表面有纳米花状CuCl2薄膜的AAO,其激发中心在290 nm,发射中心在415 nm,与基底AAO位置完全相同,但发光强度从127 cd提高到183 cd;对比宏观CuCl2粉末、AAO薄膜的激发和发射光谱,分析认为生长有纳米花状CuCl2的AAO薄膜发光强度提高的原因是该层表面的纳米结构形貌。 相似文献