全文获取类型
收费全文 | 10356篇 |
免费 | 1991篇 |
国内免费 | 995篇 |
专业分类
化学 | 6882篇 |
晶体学 | 78篇 |
力学 | 682篇 |
综合类 | 88篇 |
数学 | 1228篇 |
物理学 | 4384篇 |
出版年
2024年 | 9篇 |
2023年 | 243篇 |
2022年 | 244篇 |
2021年 | 360篇 |
2020年 | 436篇 |
2019年 | 423篇 |
2018年 | 355篇 |
2017年 | 340篇 |
2016年 | 518篇 |
2015年 | 485篇 |
2014年 | 555篇 |
2013年 | 759篇 |
2012年 | 933篇 |
2011年 | 1033篇 |
2010年 | 650篇 |
2009年 | 676篇 |
2008年 | 671篇 |
2007年 | 576篇 |
2006年 | 531篇 |
2005年 | 439篇 |
2004年 | 343篇 |
2003年 | 280篇 |
2002年 | 245篇 |
2001年 | 211篇 |
2000年 | 212篇 |
1999年 | 197篇 |
1998年 | 205篇 |
1997年 | 197篇 |
1996年 | 146篇 |
1995年 | 202篇 |
1994年 | 170篇 |
1993年 | 125篇 |
1992年 | 101篇 |
1991年 | 86篇 |
1990年 | 91篇 |
1989年 | 68篇 |
1988年 | 43篇 |
1987年 | 37篇 |
1986年 | 37篇 |
1985年 | 21篇 |
1984年 | 19篇 |
1983年 | 20篇 |
1982年 | 12篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1957年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Christian W. Pester Justin E. Poelma Benjaporn Narupai Shrayesh N. Patel Gregory M. Su Thomas E. Mates Yingdong Luo Christopher K. Ober Craig J. Hawker Edward J. Kramer 《Journal of polymer science. Part A, Polymer chemistry》2016,54(2):253-262
In an attempt to create a polymer brush-based platform for the systematic study for anti-biofouling surfaces, the benefits of surface initiated, visible light-mediated radical polymerization are utilized to fabricate well-defined, chemically ambiguously patterned surfaces. A variety of analytical tools are used to illustrate the precise tuning of surface chemistry and thoroughly characterize spatially well-defined, hydrophilic/hydrophobic surfaces composed of poly(ethylene glycol methacrylate) and poly(trifluoroethyl methacrylate) with chemical definition on the micron scale. Advantages of both visible light-mediated photopolymerization and traditional copper-catalyzed atom transfer radical polymerization are combined to achieve both high spatial control and expanded monomer tolerance. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 253–262 相似文献
92.
93.
Temperature‐dependent phase‐segregation behavior and antifouling performance of UV‐curable methacrylated PDMS/PEG coatings 下载免费PDF全文
Yunjiao Gu Shuxue Zhou Huali Luo Limin Wu Wei Gao Jinlong Yang 《Journal of Polymer Science.Polymer Physics》2016,54(16):1612-1623
Controllable phase segregation adjustment for immiscible polymer blends has always been tough, which hinders the development of amphiphilic antifouling coatings from more accessible blends. Herein, methacrylated poly(dimethylsiloxane) (PDMS‐MA) was synthesized and mixed with poly(ethylene glycol)methylether methacrylate (PEG‐MA). It was interestingly discovered that these PDMS‐MA/PEG‐MA blends displayed upper critical solution temperatures (UCST) due to thermo‐induced conformational change of PEG‐MA and the UCST changed with PDMS‐MA/PEG‐MA mass ratios. Micro‐/nano‐phase segregation, nanophase segregation, or homogenous morphology were therefore achieved. These PDMS‐MA/PEG‐MA blends with different mass ratios were UV‐cured under varying temperatures to fabricate coatings. Their surface morphology and wettability are readily adjusted by phase segregation. For the first time, highly hydrophilic surface was achieved for coatings with microphase segregation because of the exposure of PEG‐rich domains, which exhibited an enhanced protein resistance against bovine serum albumin (BSA). Anti‐bacterial performance (Shewanella loihica) was also observed for these PDMS/PEG coatings. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1612–1623 相似文献
94.
Tuning the Upconversion Luminescence Lifetimes of KYb2F7:Ho3+ Nanocrystals for Optical Multiplexing 下载免费PDF全文
Dr. Mingye Ding Prof. Daqin Chen Danyang Ma Peng Liu Dr. Kaixin Song Dr. Hongwei Lu Prof. Zhenguo Ji 《Chemphyschem》2015,16(18):3784-3789
Conventional luminescent color coding is limited by spectral overlap and the interference of background fluorescence, thus restricting the number of distinguishable identities that can be used in practice. Here, we demonstrate the possibility of generating diverse time‐domain codes, specially designed for a single emission band, using lanthanide‐doped upconversion nanocrystals. Based on the knowledge of concentration quenching, the upconversion luminescence kinetics of KYb2F7: Ho3+ nanocrystals can be precisely controlled by modifying the dopant concentration of Ho3+ ions, resulting in a tunable emission lifetime from 75.8 to 1944.5 μs, which suggests the practicality of these time‐domain codes for optical multiplexing. 相似文献
95.
Anh T. Vu Xinying Wang S. Ranil Wickramasinghe Bing Yu Hua Yuan Hailin Cong Yongli Luo Jianguo Tang 《Journal of separation science》2015,38(16):2819-2825
Hydrophobic interaction membrane chromatography has gained interest due to its excellent performance in the purification of humanized monoclonal antibodies. The membrane material used in hydrophobic interaction membrane chromatography has typically been commercially available polyvinylidene fluoride. In this contribution, newly developed inverse colloidal crystal membranes that have uniform pores, high porosity and, therefore, high surface area for protein binding are used as hydrophobic interaction membrane chromatography membranes for humanized monoclonal antibody immunoglobulin G purification. The capacity of the inverse colloidal crystal membranes developed here is up to ten times greater than commercially available polyvinylidene fluoride membranes with a similar pore size. This work highlights the importance of developing uniform pore size high porosity membranes in order to maximize the capacity of hydrophobic interaction membrane chromatography. 相似文献
96.
Nanostructured copper‐coated solid‐phase microextraction fiber for gas chromatographic analysis of dibutyl phthalate and diethylhexyl phthalate environmental estrogens 下载免费PDF全文
A novel nanostructured copper‐based solid‐phase microextraction fiber was developed and applied for determining the two most common types of phthalate environmental estrogens (dibutyl phthalate and diethylhexyl phthalate) in aqueous samples, coupled to gas chromatography with flame ionization detection. The copper film was coated onto a stainless‐steel wire via an electroless plating process, which involved a surface activation process to improve the surface properties of the fiber. Several parameters affecting extraction efficiency such as extraction time, extraction temperature, ionic strength, desorption temperature, and desorption time were optimized by a factor‐by‐factor procedure to obtain the highest extraction efficiency. The as‐established method showed wide linear ranges (0.05–250 μg/L). Precision of single fiber repeatability was <7.0%, and fiber‐to‐fiber repeatability was <10%. Limits of detection were 0.01 μg/L. The proposed method exhibited better or comparable extraction performance compared with commercial and other lab‐made fibers, and excellent thermal stability and durability. The proposed method was applied successfully for the determination of model analytes in plastic soaking water. 相似文献
97.
Preparation of 17β‐estradiol‐imprinted material by surface‐initiated atom transfer radical polymerization and its application 下载免费PDF全文
Yanru Gong Yuling Niu Xiaohan Gong Meihua Ma Xiaowei Ren Weihua Zhu Ruiming Luo Bolin Gong 《Journal of separation science》2015,38(7):1254-1261
A novel 17β‐estradiol molecularly imprinted polymer was grafted onto the surface of initiator‐immobilized silica by surface‐initiated atom transfer radical polymerization. The resulting molecularly imprinted polymer was characterized by elemental analysis and thermogravimetric analysis. The binding property of molecularly imprinted polymer for 17β‐estradiol was also studied with both static and dynamic methods. The results showed that the molecularly imprinted polymer possessed excellent recognition capacity for 17β‐estradiol (180.65 mg/g at 298 K), and also exhibited outstanding selectivity for 17β‐estradiol over the other competitive compounds (such as testosterone and progesterone). Then, the determination of trace 17β‐estradiol in beef samples was successfully developed by using molecularly imprinted polymer solid‐phase extraction coupled with high‐performance liquid chromatography. The limit of detection was 0.25 ng/mL, and the amount of 17β‐estradiol in beef samples was detected at 2.83 ng/g. This work proposed a sensitive, rapid, reliable, and convenient approach for the determination of trace 17β‐estradiol in complicated beef samples. 相似文献
98.
Determination of selected polychlorinated biphenyls in soil and earthworm (Eisenia fetida) using a QuEChERS‐based method and gas chromatography with tandem MS 下载免费PDF全文
Zeying He Lu Wang Yi Peng Ming Luo Wenwen Wang Xiaowei Liu 《Journal of separation science》2015,38(21):3766-3773
Soil and earthworms are important objects in soil pollution assessment and environmental behavior and toxicity study for polychlorinated biphenyls. Accelerated solvent extraction and solid‐phase extraction are generally required for the extraction and clean‐up of polychlorinated biphenyls in soil and earthworm, which are tedious and time‐consuming. In this work, a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure combined with gas chromatography and triple quadrupole mass spectrometry was developed for the determination of 20 selected polychlorinated biphenyl congeners in soil and earthworm. Different extraction times, solvents, and clean‐up adsorbents were compared and optimized. The average recoveries from spiked soils ranged between 70 and 120% with satisfactory relative standard deviations for all the polychlorinated biphenyls. In earthworm, the recoveries of polychlorinated biphenyls 180, 183, and 189 were relatively low (< 70% in some spiking levels) compared to that of the other polychlorinated biphenyls. The limits of quantification were in the range of 0.01–0.05 ng/g. The method was successfully applied to the analysis of 66 agricultural soils. To our knowledge, a combined method based on QuEChERS for the determination of polychlorinated biphenyls in soil and earthworms has not been published before. The procedure proved to be simple, sensitive, efficient, and environmentally friendly. 相似文献
99.
100.