全文获取类型
收费全文 | 4718篇 |
免费 | 174篇 |
国内免费 | 11篇 |
专业分类
化学 | 2675篇 |
晶体学 | 32篇 |
力学 | 157篇 |
数学 | 476篇 |
物理学 | 1563篇 |
出版年
2023年 | 33篇 |
2022年 | 45篇 |
2021年 | 76篇 |
2020年 | 91篇 |
2019年 | 103篇 |
2018年 | 99篇 |
2017年 | 66篇 |
2016年 | 145篇 |
2015年 | 97篇 |
2014年 | 136篇 |
2013年 | 302篇 |
2012年 | 270篇 |
2011年 | 310篇 |
2010年 | 191篇 |
2009年 | 175篇 |
2008年 | 239篇 |
2007年 | 231篇 |
2006年 | 246篇 |
2005年 | 209篇 |
2004年 | 147篇 |
2003年 | 129篇 |
2002年 | 95篇 |
2001年 | 77篇 |
2000年 | 73篇 |
1999年 | 46篇 |
1998年 | 43篇 |
1997年 | 41篇 |
1996年 | 45篇 |
1995年 | 54篇 |
1994年 | 44篇 |
1993年 | 58篇 |
1992年 | 46篇 |
1991年 | 38篇 |
1990年 | 52篇 |
1989年 | 49篇 |
1988年 | 41篇 |
1987年 | 43篇 |
1985年 | 54篇 |
1984年 | 48篇 |
1983年 | 43篇 |
1982年 | 41篇 |
1981年 | 44篇 |
1980年 | 46篇 |
1979年 | 38篇 |
1978年 | 44篇 |
1977年 | 40篇 |
1976年 | 38篇 |
1975年 | 33篇 |
1974年 | 36篇 |
1973年 | 36篇 |
排序方式: 共有4903条查询结果,搜索用时 15 毫秒
1.
Analysis Mathematica - In this paper, in the light of weighted sharing of sets, we investigate the possible uniqueness of meromorphic function of restricted hyper order with its linear c-shift... 相似文献
2.
Molecular Diversity - Quantitative structure–activity relationship (QSAR) and read-across techniques have recently been merged into a new emerging field of read-across... 相似文献
3.
Automotive proton exchange membrane fuel cell stacks need to meet manufacturer specified rated beginning-of-life (BOL) performance before being assembled into vehicles and shipped off to customers. The process of “breaking-in” of a freshly assembled stack is often referred to as “conditioning.” It has become an intensely researched area especially in automotive companies, where imminent commercialization of fuel cell electric vehicles (FCEVs) demands a short, energy- and cost-efficient, and practical conditioning protocol. Significant advances in reducing the conditioning time from 1 to 2 days to as low as 4h or less, in some cases without the use of additional inert gases such as nitrogen, and with minimal use of hydrogen, and specialized test stations will be discussed. 相似文献
4.
Archiv der Mathematik - Let G be a simple simply-connected connected linear algebraic group over $${\mathbb {C}}$$ . We prove a 2-birational Torelli theorem for the moduli space of semistable... 相似文献
5.
Subrata Hazra Somenath Mahato Kanak Kanti Das Dr. Santanu Panda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(44):e202200556
Heteroaryl boronic acids and esters are extremely important and valuable intermediates because of their wide application in the synthesis of marketed drugs and bioactive compounds. Over the last couple of decades, the construction of highly important heteroaryl carbon-boron bonds has created huge attention. The transition-metal-free protocols are more green, less sensitive to air and moisture, and also economically advantageous over the transition-metal-based protocols. The transition-metal-free C−H borylation of heteroarenes and C−X (X=halogen) borylation of heteroaryl halides represents an excellent approach for their synthesis. Also, various cyclization and alkyne activation protocols have been recently established for their synthesis. The goal of this review article is to summarize the existing literature and the current state of the art for transition-metal-free synthesis of heteroaryl boronic acid and esters. 相似文献
6.
Sing Lai Cong Roy Anitha Hui Lok Yong Mun Chan Sook Rajak Harish Karunakaran Rohini Ravichandran Veerasamy 《Structural chemistry》2022,33(3):649-669
Structural Chemistry - Quinoline- and acridine-based drugs are widely used as anti-breast cancer agents. These drugs act through various mechanisms of action; for example, neratinib acts on... 相似文献
7.
Seema Yadav Sriparna Ray Ajeet Singh Shaikh M. Mobin Tapta Kanchan Roy Chandrakanta Dash 《应用有机金属化学》2020,34(11):e5942
Dinuclear gold(I)-N-heterocyclic carbene complexes were developed for the hydrohydrazidation of terminal alkynes. The gold(I)-N-heterocyclic carbene complexes 2a-2b were synthesized in good yields from silver complexes synthesized in situ, which in turn were obtained from the corresponding imidazolium salts with Ag2O in dichloromethane as a solvent. The new air-stable gold(I)-NHC complexes, 2a - 2b, were characterized using NMR spectroscopy, elemental analysis, infrared, and mass spectroscopy studies. The gold(I) complex 2a was characterized using X-ray crystallography. Bis-N-heterocyclic carbene–based gold(I) complexes 2a - 2b exhibited excellent catalytic activities for hydrohydrazidation of terminal alkynes yielding acylhydrazone derivatives. The working catalytic system can be used in gram-scale synthesis. In addition, the catalytic reaction mechanism of the hydrohydrazidation of terminal alkynes by gold(I)-NHC complex was studied in detail using density functional theory. 相似文献
8.
9.
Shyam Sundar Mondal Namita Jaiswal Partha Sarathi Bera Ranjay K. Tiwari Jogendra Nath Behera Nripen Chanda Subhas Ghosal Tanmoy Kumar Saha 《应用有机金属化学》2021,35(1)
A series of copper (II) ( 1 and 3 ) and cobalt (II/III) ( 2 , 4 and 5 ) complexes comprising different imino‐phenolate ligands DCH , DTH and DBH 2 (where DCH = 2,4‐dichloro‐6‐((mesitylimino)methyl)phenol, DTH = 2,4‐di‐tert‐butyl‐6‐((mesitylimino)methyl) phenol and DBH 2 = 2,4‐dibromo‐6‐((mesitylimino)methyl)phenol) have been prepared with excellent yield and high purity. By utilizing different spectroscopic tools such as UV–visible, electrospray ionization (ESI)‐mass, Fourier‐transform infrared (FTIR) spectrometry and elemental analysis, the prepared complexes ( 1 – 5 ) were thoroughly characterized. The molecular structure of the synthesized complexes was ascertained by using single‐crystal X‐ray diffraction studies (SCXRDs). The experiment reveals that Complexes 1 – 5 bind to calf thymus DNA (CT‐DNA) through non‐intercalative way with good interacting abilities. However, 1 – 5 are excellent quenchers of the fluorescence intensity of bovine serum albumin (BSA) following the static pathway. Additionally, they had shown remarkable cytotoxic potential against MCF‐7 (mammary gland adenocarcinoma) and A549 (lung adenocarcinoma) cell lines. The IC50 values associated with these complexes were much lower than the conventional drug cisplatin. Apoptosis‐induced cell death was confirmed from the DNA fragmentation studies and Hoechst 33342 staining. The 2′,7′‐dichlorofluorescein diacetate (DCFDA) assay indicates that the complex mediated reactive oxygen species (ROS) generation is accountable for governing the apoptosis mechanism via oxidative cell distress. Apart from these studies, by carrying out density functional theory (DFT) method, highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energy gap calculations and optimized structures of the synthesized complexes were accomplished. 相似文献
10.