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951.
Xinyi Li Zengxin Qi Duan Ni Shaoyong Lu Liang Chen Xiangyu Chen 《Molecules (Basel, Switzerland)》2021,26(18)
Mutations in leucine-rich repeat kinase 2 (LRRK2) are recognized as the most frequent cause of Parkinson’s disease (PD). As a multidomain ROCO protein, LRRK2 is characterized by the presence of both a Ras-of-complex (ROC) GTPase domain and a kinase domain connected through the C-terminal of an ROC domain (COR). The bienzymatic ROC–COR–kinase catalytic triad indicated the potential role of GTPase domain in regulating kinase activity. However, as a functional GTPase, the detailed intrinsic regulation of the ROC activation cycle remains poorly understood. Here, combining extensive molecular dynamics simulations and Markov state models, we disclosed the dynamic structural rearrangement of ROC’s homodimer during nucleotide turnover. Our study revealed the coupling between dimerization extent and nucleotide-binding state, indicating a nucleotide-dependent dimerization-based activation scheme adopted by ROC GTPase. Furthermore, inspired by the well-known R1441C/G/H PD-relevant mutations within the ROC domain, we illuminated the potential allosteric molecular mechanism for its pathogenetic effects through enabling faster interconversion between inactive and active states, thus trapping ROC in a prolonged activated state, while the implicated allostery could provide further guidance for identification of regulatory allosteric pockets on the ROC complex. Our investigations illuminated the thermodynamics and kinetics of ROC homodimer during nucleotide-dependent activation for the first time and provided guidance for further exploiting ROC as therapeutic targets for controlling LRRK2 functionality in PD treatment. 相似文献
952.
Density and impurity profile behaviours in HL-2A tokamak with different gas fuelling methods 下载免费PDF全文
The electron density profile peaking and the impurity accumulation
in the HL-2A tokamak plasma are observed when three kinds of
fuelling methods are separately used at different fuelling particle
locations. The density profile becomes more peaked when the
line-averaged electron density approaches the Greenwald density limit
nG and, consequently, impurity accumulation is often
observed. A linear increase regime in the density range ne<
0.6nG and a saturation regime in ne > 0.6nG
are obtained. There is no significant difference in achieved density
peaking factor fne between the supersonic molecular beam
injection (SMBI) and gas puffing into the plasma main chamber.
However, the achieved fne is relatively low, in particular,
in the case of density below 0.7nG, when the working
gas is puffed into the divertor chamber. A discharge with a
density as high as 1.2nG, i.e. ne = 1.2nG,
can be achieved by SMBI just after siliconization as a wall
conditioning. The metallic impurities, such as iron and chromium,
also increase remarkably when the impurity accumulation happens. The
mechanism behind the density peaking and impurity accumulation is
studied by investigating both the density peaking factor versus the
effective collisionality and the radiation peaking versus density
peaking. 相似文献
953.
Yangyang Dai Feng Duan Fan Feng Zhe Sun Yu Zhang Cesar F. Caiafa Pere Marti-Puig Jordi Sol-Casals 《Entropy (Basel, Switzerland)》2021,23(9)
An electroencephalogram (EEG) is an electrophysiological signal reflecting the functional state of the brain. As the control signal of the brain–computer interface (BCI), EEG may build a bridge between humans and computers to improve the life quality for patients with movement disorders. The collected EEG signals are extremely susceptible to the contamination of electromyography (EMG) artifacts, affecting their original characteristics. Therefore, EEG denoising is an essential preprocessing step in any BCI system. Previous studies have confirmed that the combination of ensemble empirical mode decomposition (EEMD) and canonical correlation analysis (CCA) can effectively suppress EMG artifacts. However, the time-consuming iterative process of EEMD may limit the application of the EEMD-CCA method in real-time monitoring of BCI. Compared with the existing EEMD, the recently proposed signal serialization based EEMD (sEEMD) is a good choice to provide effective signal analysis and fast mode decomposition. In this study, an EMG denoising method based on sEEMD and CCA is discussed. All of the analyses are carried out on semi-simulated data. The results show that, in terms of frequency and amplitude, the intrinsic mode functions (IMFs) decomposed by sEEMD are consistent with the IMFs obtained by EEMD. There is no significant difference in the ability to separate EMG artifacts from EEG signals between the sEEMD-CCA method and the EEMD-CCA method (p > 0.05). Even in the case of heavy contamination (signal-to-noise ratio is less than 2 dB), the relative root mean squared error is about 0.3, and the average correlation coefficient remains above 0.9. The running speed of the sEEMD-CCA method to remove EMG artifacts is significantly improved in comparison with that of EEMD-CCA method (p < 0.05). The running time of the sEEMD-CCA method for three lengths of semi-simulated data is shortened by more than 50%. This indicates that sEEMD-CCA is a promising tool for EMG artifact removal in real-time BCI systems. 相似文献
954.
Yanchun Shi Chen Gao Enhui Xing Jimei Zhang Feng Duan He Zhao Yongbing Xie 《中国化学快报》2022,33(2):803-806
Meso-Ni@HZSM-5 bi-functional catalysts were successfully post-encapsulated with about 3–7 nm Ni nanoparticles within HZSM-5 crystals,which exhibited significantly efficient conversion activity (67.4g[palmitic acid]g[Ni]-1h-1) of palmitic acid and 100%selectivity of hydrocarbons with the outstanding stability during recycling application,compared to the impregnated Ni/HZSM-5 catalyst (14.0 g[palmitic acid]g[Ni]-1h-1). 相似文献
955.
傅里叶变换红外光谱用于胃镜样品的检测 总被引:4,自引:3,他引:1
应用傅里叶变换红外光谱(FTIR) 法对184例不同病理状态的胃镜下活检组织样品进行检测和分析,结果表明,慢性浅表性胃炎的基本谱图特征包括:较强的酰胺Ⅱ带;1 460 cm-1处的峰强高于1 400 cm-1处的峰强。典型的胃癌组织的谱图特征包括:较低的酰胺Ⅱ带;1 460 cm-1处的峰强低于1 400 cm-1处的峰强;1 300 cm-1的峰强明显增加。慢性萎缩性胃炎呈现出部分胃癌的光谱特征。这一结果表明,应用FTIR可以对胃镜下活检的小块组织进行鉴别诊断。 相似文献
956.
Using the standard reductive perturbation technique,a nonlinear Schroedinger equation is derived to study the modulational instability of finite-amplitude ion-acoustic waves in a non-magnetized warm plasma.It is found that the inclusion of ion temperature in the equation modifies the nature of the ion-acoustic wave stability and the soliton stuctures.The effects of ion plasma temperature on the modulational stability and ion-acoustic wave properties are inestigated in detail. 相似文献
957.
Jia‐Geng Liu Jing‐Jing Nie Duan‐Jun Xu Yuan‐Zhi Xu Jing‐Yun Wu Michael Y. Chiang 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):354-355
The title complex, [CuCl2(C6H6N4S2)], has a flattened tetrahedral coordination. The CuII atom is located on a twofold rotation axis and is coordinated by two N atoms from a chelating 2,2′‐diamino‐4,4′‐bi‐1,3‐thiazole ligand and by two Cl atoms. Intramolecular hydrogen bonding exists between the amino groups of the 2,2′‐diamino‐4,4′‐bi‐1,3‐thiazole ligand and the Cl atoms. The intermolecular separation of 3.425 (1) Å between parallel bithiazole rings suggests there is a π–π interaction between them. 相似文献
958.
959.
气相色谱与串联质谱联用检测血清中脱氢表雄酮 总被引:1,自引:0,他引:1
在晚期前列腺癌雄激素全阻断治疗最终导致前列腺癌雄激素非依赖性的转变过程中,肾上腺分泌脱氢表雄酮(DHEA)被认为是重要的诱因。本研究主要利用睾丸摘除(去势)大鼠模型,对血清中DHEA浓度进行测定。采用了气相色谱与串联质谱联用(GC-MS/MS)技术,建立了高灵敏度的测定大鼠血清中脱氢表雄酮(DHEA)的方法。样品经过甲醇沉蛋白,而后固相萃取提取血清中微量的DHEA,通过七氟丁酸酐(HF-BA)衍生,采用GC-MS/MS测定。对固相萃取条件、衍生化条件以及质谱测定条件进行优化。DHEA在0.1~100μg/L范围内线性良好,相关系数r为0.9996;在2~50μg/L浓度范围内,加标回收率在99%~106%之间;相对标准偏差小于5%。本方法灵敏度高,选择性好,可满足临床对于血清样品中DHEA的测定要求。对去势大鼠血清中DHEA测定结果表明,去势后DHEA明显上升。 相似文献
960.