全文获取类型
收费全文 | 2650篇 |
免费 | 227篇 |
国内免费 | 198篇 |
专业分类
化学 | 1629篇 |
晶体学 | 59篇 |
力学 | 80篇 |
综合类 | 26篇 |
数学 | 361篇 |
物理学 | 920篇 |
出版年
2023年 | 46篇 |
2022年 | 51篇 |
2021年 | 62篇 |
2020年 | 70篇 |
2019年 | 69篇 |
2018年 | 73篇 |
2017年 | 75篇 |
2016年 | 97篇 |
2015年 | 78篇 |
2014年 | 103篇 |
2013年 | 144篇 |
2012年 | 188篇 |
2011年 | 173篇 |
2010年 | 125篇 |
2009年 | 141篇 |
2008年 | 149篇 |
2007年 | 127篇 |
2006年 | 104篇 |
2005年 | 103篇 |
2004年 | 71篇 |
2003年 | 72篇 |
2002年 | 76篇 |
2001年 | 46篇 |
2000年 | 29篇 |
1999年 | 37篇 |
1998年 | 28篇 |
1997年 | 21篇 |
1996年 | 31篇 |
1995年 | 36篇 |
1994年 | 27篇 |
1993年 | 33篇 |
1992年 | 40篇 |
1991年 | 26篇 |
1990年 | 29篇 |
1989年 | 31篇 |
1988年 | 21篇 |
1987年 | 23篇 |
1986年 | 23篇 |
1985年 | 30篇 |
1984年 | 32篇 |
1983年 | 26篇 |
1982年 | 15篇 |
1980年 | 14篇 |
1979年 | 19篇 |
1978年 | 14篇 |
1976年 | 17篇 |
1975年 | 13篇 |
1974年 | 17篇 |
1973年 | 26篇 |
1972年 | 16篇 |
排序方式: 共有3075条查询结果,搜索用时 15 毫秒
121.
Rui Feng Yong Zhang He Li Dan Wu Xiaodong Xin Sen Zhang Haiqin Yu Qin Wei Bin Du 《Analytica chimica acta》2013
Nano-montmorillonites belong to aluminosilicate clay minerals with innocuity, high specific surface area, ion exchange, and favorable adsorption property. Due to the excellent properties, montmorillonites can be used as labels for the electrochemical immunosensors. In this study, nano-montmorillonites were converted to sodium montmorillonites (Na-Mont) and further utilized for the immobilization of thionine (TH), horseradish peroxidase (HRP) and the secondary anti-zeranol antibody (Ab2). The modified particles, Na-Mont-TH-HRP-Ab2 were used as labels for immunosensors to detect zeranol. This protocol was used to prepare the immunosensor with the primary antibody (Ab1) immobilized onto the nanoporous gold films (NPG) modified glassy carbon electrode (GCE) surface. Within zeranol concentration range (0.01–12 ng mL−1), a linear calibration plot (Y = 0.4326 + 8.713 X, r = 0.9996) was obtained with a detection limit of 3 pg mL−1 under optimal conditions. The proposed immunosensor showed good reproducibility, selectivity, and stability. This new type of immunosensors with montmorillonites and NPG as labels may provide potential applications for the detection of zeranol. 相似文献
122.
One‐pot protocol for the synthesis of novel class of triazole linked 2‐sugar and 2‐aryl substituted benzimidazoles has been developed. The rapid and simple method involves copper (I) catalyzed simultaneous formation of benzimidazole and triazole rings at room temperature and in high yield. 相似文献
123.
A series of β-amino alcohols derivatives were synthesized from (R)-2-amino-1-butanol and (S)-1,2-propanediol, and they have been used as organocatalaysts in the racemic ring opening of epoxide in good yields with high enantiomeric excess (up to 97%). 相似文献
124.
125.
The mixed-metal cluster Yb4O4(OiPr)16Na12 has been synthesized and structurally determined by IR, elemental analysis, and single-crystal X-ray diffraction. The crystal belongs to the cubic system, space group P23 with a = b = c = 13.9788(3), V = 2731.55(10)3 , Z = 1, Dc = 1.202 g/cm 3 , Mr = 1977.42, = 3.480 mm-1 , F(000) = 972, the final R = 0.0288 and wR = 0.1511 for 1677 observed reflections with Ⅰ > 2σ(Ⅰ). X-ray analysis reveals that Yb4O4 (OiPr)16Na12 is centrosym-metric and the structure contains four ytterbium metals and twelve sodium metals, and each ytterbium atom is coordinated by six oxygen atoms. In addition, an ancillary computational analysis of the optimized molecular unit was provided. The large energy gap (3.31 eV) between HOMO and LUMO indicates that the structure framework is particularly stable. 相似文献
126.
127.
The focus of this article is on the analysis of repairable systems that are subject to multiple sources of recurrence. The event of interest at the system level is assumed to be caused by the earliest occurrence of a source, thereby conforming to a series system competing risks framework. Parametric inference is carried out under the power law process model that has found significant attention in industrial applications. Dependence among the cause‐specific recurrent processes is induced via a shared frailty structure. The theoretical inference results are implemented to a warranty database for a fleet of automobiles, for which the warranty repair is triggered by the failure of one of many components. Extensive finite‐sample simulation is carried out to supplement the asymptotic findings. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
128.
129.
Excellent Performance of Few‐Layer Borocarbonitrides as Anode Materials in Lithium‐Ion Batteries 下载免费PDF全文
Borocarbonitrides (BxCyNz) with a graphene‐like structure exhibit a remarkable high lithium cyclability and current rate capability. The electrochemical performance of the BxCyNz materials, synthesized by using a simple solid‐state synthesis route based on urea, was strongly dependent on the composition and surface area. Among the three compositions studied, the carbon‐rich compound B0.15C0.73N0.12 with the highest surface area showed an exceptional stability (over 100 cycles) and rate capability over widely varying current density values (0.05–1 A g?1). B0.15C0.73N0.12 has a very high specific capacity of 710 mA h g?1 at 0.05 A g?1. With the inclusion of a suitable additive in the electrolyte, the specific capacity improved drastically, recording an impressive value of nearly 900 mA h g?1 at 0.05 A g?1. It is believed that the solid–electrolyte interphase (SEI) layer at the interface of BxCyNz and electrolyte also plays a crucial role in the performance of the BxCyNz . 相似文献
130.
Dr. Zijie Zhang Dr. Jiuxing Li Jimmy Gu Ryan Amini Hannah D. Stacey Jann C. Ang Dawn White Prof. Dr. Carlos D. M. Filipe Prof. Dr. Karen Mossman Prof. Dr. Matthew S. Miller Prof. Dr. Bruno J. Salena Prof. Dr. Deborah Yamamura Dr. Payel Sen Prof. Dr. Leyla Soleymani Prof. Dr. John D. Brennan Prof. Dr. Yingfu Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(15):e202200078
We report on a unique DNA aptamer, denoted MSA52, that displays universally high affinity for the spike proteins of wildtype SARS-CoV-2 as well as the Alpha, Beta, Gamma, Epsilon, Kappa, Delta and Omicron variants. Using an aptamer pool produced from round 13 of selection against the S1 domain of the wildtype spike protein, we carried out one-round SELEX experiments using five different trimeric spike proteins from variants, followed by high-throughput sequencing and sequence alignment analysis of aptamers that formed complexes with all proteins. A previously unidentified aptamer, MSA52, showed Kd values ranging from 2 to 10 nM for all variant spike proteins, and also bound similarly to variants not present in the reselection experiments. This aptamer also recognized pseudotyped lentiviruses (PL) expressing eight different spike proteins of SARS-CoV-2 with Kd values between 20 and 50 pM, and was integrated into a simple colorimetric assay for detection of multiple PL variants. This discovery provides evidence that aptamers can be generated with high affinity to multiple variants of a single protein, including emerging variants, making it well-suited for molecular recognition of rapidly evolving targets such as those found in SARS-CoV-2. 相似文献