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891.
配体[C5Me4HR][R=4-BrPh(1),(MeC5H3N)CH2(2)]分别与Mo(CO)6,Ru3(CO)12和Fe(CO)5在二甲苯中加热回流,得到了6个双核配合物trans-[η5-C5Me4R]2Mo2(CO)6(3,4),trans-[(η5-C5Me4R)Ru(CO)(μ-CO)]2(5,6)和trans-[η5-(C5Me4R)Fe(CO)(μ-CO)]2(7,8,).通过元素分析、红外光谱、核磁共振氢谱对配合物的结构进行了表征,并用X-射线单晶衍射法测定了配合物3,5,6和8的结构. 相似文献
892.
建立了硝酸提取,高效液相色谱一原子荧光联用技术测定方便面中不同砷形态的分析方法。样品经0.15mol/L盐酸溶液超声提取后离心过滤,上机测试。实验表明:砷的4种形态亚砷酸[As(Ⅲ)]、砷酸[As(V)]、一甲基胂酸(MMA)和二甲基胂酸(DMA)的线性范围为0-50μg/L,相关系数(r)均优于0.9990,检出限在2~8μg/L之间,砷各形态的测量重复性(以RSD表示)均小于5%,样品的加标回收率为78%-118%。同时用原子荧光光度计检测了样品中总砷,并将两种方法测定结果进行了对比,结果符合理论以及文献报道。该方法操作简单快速、结果准确可靠,适用于方便面中砷形态的分析测定。 相似文献
893.
Ik Hyun Kwon Hye Ryoung Park Young Youp Song 《Russian Journal of Electrochemistry》2013,49(3):221-227
LiNi1 ? y Ti y O2 (0.000 ≤ y ≤ 0.100) and LiNi0.990M0.010O2 (M = Zn, Al, and Ti) were synthesized by the combustion method. The effects of Zn, Al and Ti substitution for Ni of LiNiO2 on the electrochemical properties of LiNiO2 were investigated. LiNi0.995Ti0.005O2 has the largest first discharge capacity (188.1 mA h/g) among the Ti-substituted samples. LiNi0.990Ti0.010O2 has a relatively large first discharge capacity (185.5 mA h/g) and a relatively good cycling performance. Among LiNi0.990M0.010O2 (M = Ni, Zn, Al, and Ti), LiNiO2 has the largest discharge capacities at a rate of 0.1 C from n = 1(189.3 mA h/g) to n = 10. LiNi0.990Al0.010O2 has the lowest discharge capacities from n = 1 to n = 10, but it has the best cycling performance. LiNi0.990Zn0.010O2 showed poor crystallinity, LiNi0.990Ti0.010O2 showed high cation mixing, and LiNi0.990Al0.010O2 had good crystallinity and showed low cation mixing. Fewer occurrence of phase transitions and the least change of the ?dx/|dV| vs. voltage curve at the second cycle from the curve at the first cycle of LiNi0.990Al0.010O2 suggest that Al substitution stabilizes the structure and leads to a good cycling performance. 相似文献
894.
Jun Zhang Lingzhi Shangguan Shaomin Shuang Chuan Dong 《Russian Journal of Electrochemistry》2013,49(9):888-894
A nickel hydroxide-modified nickel electrode (Ni(OH)2/Ni) was successfully prepared by the cyclic voltammetry (CV) method and the electrocatalytic properties of the electrode for formaldehyde and methanol oxidation have been investigated respectively. The Ni(OH)2/Ni electrode exhibits high electrocatalytic activity in the reaction. A new method has been developed for formaldehyde determination at the nickel hydroxide-modified nickel electrode and the experimental parameters were optimized. The oxidation peak current is linearly proportional to the concentration of formaldehyde in the range of 7.0 × 10?5 to 1.6 × 10?2 M with a detection limit of 2.0 × 10?5 M. Recoveries of artificial samples are between 93.3 and 103.5%. The effect of scan rate and methanol concentration on the electrochemical behavior of methanol were investigated respectively. 相似文献
895.
896.
897.
Shuhai Lin Hongde Liu Basem Kanawati Liangfeng Liu Jiyang Dong Min Li Jiandong Huang Philippe Schmitt-Kopplin Zongwei Cai 《Analytical and bioanalytical chemistry》2013,405(15):5105-5117
In the wake of genomics, metabolomics characterizes the small molecular metabolites revealing the phenotypes induced by gene mutants. To address the metabolic signatures in the hippocampus of the amyloid-beta (Aβ) peptides produced in transgenic (Tg) CRND8 mice, high-field ion cyclotron resonance–Fourier transform mass spectrometry supported by LC-LTQ-Orbitrap was introduced to profile the extracted metabolites. More than 10,000 ions were detected in the mass profile for each sample. Subsequently, peak alignment and the 80 % rule followed by feature selection based on T score computation were performed. The putative identification was also conducted using the highly accurate masses with isotopic distribution by interfacing the MassTRIX database as well as MS/MS fragmentation generated in the LTQ-Orbitrap after chromatographic separation. Consequently, 58 differentiating masses were tentatively identified while up to 44 differentiating elemental compositions could not be biologically annotated in the databases. Nonetheless, of the putatively annotated masses, eicosanoids in arachidonic acid metabolism, fatty acid beta-oxidation disorders as well as disturbed glucose metabolism were highlighted as metabolic traits of Aβ toxicity in Tg CRND8 mice. Furthermore, a web-based bioinformatic tool was used for simulation of the metabolic pathways. As a result of the obtained metabolic signatures, the arachidonic acid metabolism dominates the metabolic perturbation in hippocampal tissues of Tg CRND8 mice compared to non-Tg littermates, indicating that Aβ toxicity functions neuroinflammation in hippocampal tissue and new theranostic opportunities might be offered by characterization of altered arachidonic acid metabolism for Alzheimer’s disease. 相似文献
898.
A multi‐channel microchip electrophoresis using a programmed step electric field strength (PSEFS) method was investigated for fast parallel detection of feline panleukopenia virus (FPV) DNA. An expanded laser beam, a 10× objective lens, and a charge‐coupled device camera were used to simultaneously detect the separations in three parallel channels using laser‐induced fluorescence detection. The parallel separations of a 100‐bp DNA ladder were demonstrated on the system using a sieving gel matrix of 0.5% poly(ethylene oxide) (Mr = 8 000 000) in the individual channels. In addition, the PSEFS method was also applied for faster DNA separation without loss of resolving power. A DNA size marker, FPV DNA sample, and a negative control were simultaneously analyzed with single‐run and one‐step detection. The FPV DNA was clearly distinguished within 30 s, which was more than 100 times faster than with conventional slab gel electrophoresis. The proposed multi‐channel microchip electrophoresis with PSEFS was demonstrated to be a simple and powerful diagnostic method to analyze multiple disease‐related DNA fragments in parallel with high speed, throughput, and accuracy. 相似文献
899.
Jaeyoung Ko Janggyoo Choi Soo Kyung Bae Jinwoong Kim Kee Dong Yoon 《Journal of separation science》2013,36(24):3860-3865
A rapid and efficient high‐performance counter‐current chromatography (HPCCC) method was developed to separate five oligostilbenes from the roots of Vitis amurensis. An n‐hexane/ethyl acetate/methanol/water system (4:8:4:10, v/v/v/v) was selected as an optimal two‐phase solvent system of which the upper phase was used as the stationary phase and the lower phase was used as the mobile one. Partition coefficient values for the target compounds under these optimized conditions were 0.28 ( 1 , ampleosin A), 7.12 ( 2 , (+)‐g‐viniferin), 2.26 ( 3 , vitisin A), 5.38 ( 4 , wilsonol C), and 11.23 ( 5 , vitisin B). Flow‐rate gradient HPCCC (4 mL/min in 0–70 min, 8 mL/min in 70–250 min) was applied to isolate the target compounds in as high purity as possible within the shortest possible run time. Under these conditions, ampelopsin A (12.1 mg), (+)‐g‐viniferin (10.4 mg), vitisin A (2.8 mg), wilsonol C (3.2 mg), and vitisin B (37 mg) were isolated with >95% purity from 150 mg of enriched oligostilbene extract. Although the KD of the last eluted compound, vitisin B (KD = 11.23), was relatively large, it was eluted in 115–145 min using the two‐phase solvent system. This study shows that HPCCC is an efficient tool for the isolation and purification of natural products. 相似文献
900.
A liquid chromatographic chiral stationary phase based on (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid was applied to the resolution of 15 analytes, including racemic rasagiline, a chiral drug for the treatment of Parkinson's disease, and its analogues. The composition of mobile phase was optimized to be ethanol/acetonitrile/acetic acid/triethylamine (80:20:0.2:0.3, v/v/v/v) by evaluating the chromatographic results for the resolution of five selected analytes under various mobile phase conditions. Under the optimized mobile phase conditions, racemic rasagiline was resolved quite well with a separation factor of 1.48 and resolution of 2.71 and its 14 analogues were also resolved reasonably well with separation factors of 1.06–1.54 and resolutions of 0.54–2.11. Among 15 analytes, racemic rasagiline was resolved best except for just one analyte. The analyte structure–enantioselectivity relationship indicated that racemic rasagiline has the most appropriate structural characteristics for resolution on the chiral stationary phase. 相似文献