全文获取类型
收费全文 | 4010篇 |
免费 | 170篇 |
国内免费 | 18篇 |
专业分类
化学 | 2790篇 |
晶体学 | 40篇 |
力学 | 95篇 |
数学 | 336篇 |
物理学 | 937篇 |
出版年
2023年 | 16篇 |
2022年 | 36篇 |
2021年 | 94篇 |
2020年 | 81篇 |
2019年 | 69篇 |
2018年 | 59篇 |
2017年 | 48篇 |
2016年 | 122篇 |
2015年 | 115篇 |
2014年 | 141篇 |
2013年 | 232篇 |
2012年 | 320篇 |
2011年 | 354篇 |
2010年 | 181篇 |
2009年 | 172篇 |
2008年 | 266篇 |
2007年 | 247篇 |
2006年 | 227篇 |
2005年 | 217篇 |
2004年 | 169篇 |
2003年 | 152篇 |
2002年 | 137篇 |
2001年 | 88篇 |
2000年 | 90篇 |
1999年 | 74篇 |
1998年 | 59篇 |
1997年 | 33篇 |
1996年 | 49篇 |
1995年 | 45篇 |
1994年 | 48篇 |
1993年 | 44篇 |
1992年 | 30篇 |
1991年 | 21篇 |
1990年 | 29篇 |
1989年 | 21篇 |
1988年 | 6篇 |
1987年 | 9篇 |
1986年 | 12篇 |
1985年 | 12篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 7篇 |
1973年 | 4篇 |
排序方式: 共有4198条查询结果,搜索用时 15 毫秒
951.
A portable CE system was developed for the identification of cattle breeds. The system had a width of 44 cm, depth of 27 cm, height of 13 cm, and a weight of only ∼8 kg and included an LIF detector, with everything integrated into a small box. The specific sizes of genes were quickly separated and detected with a high sensitivity based on the difference in the DNA mobility using a diode‐pumped solid‐state LIF detector. Using this system, the 100‐bp DNA ladder was analyzed under a 1.0% PVP (Mr=300 000) sieving gel matrix in a fused silica capillary with LODs of 4.4–13.0 pg/μL (S/N=3) for 100–3000 bp DNAs, which indicates ten times improved value than other commercialized portable CE system. The migration times and the peak areas showed good reproducibilities with relative standard deviations that were less than 0.49 and 1.3% (n=5), respectively. Based on the difference in the DNA mobility of the microsatellite and SNP markers, Korean cattle and Holstein were exactly identified as the model cattle breeds within 32 and 3.5 min, respectively. 相似文献
952.
Impact of poly(ɛ‐caprolactone) architecture on the thermomechanical and shape memory properties
下载免费PDF全文
![点击此处可从《Journal of polymer science. Part A, Polymer chemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Prashant Deshmukh Hyeongho Yoon Seungwan Cho Sook Young Yoon Omkar V. Zore Taeyoon Kim Ildoo Chung Suk‐Kyun Ahn Rajeswari M. Kasi 《Journal of polymer science. Part A, Polymer chemistry》2017,55(20):3424-3433
We report the synthesis of linear‐ and brush‐type poly(?‐caprolactone) (PCL) networks and investigate their thermal, mechanical, and shape memory behavior. Brush‐PCLs are prepared by ring‐opening metathesis polymerization (ROMP) of a norbornenyl‐functionalized ?‐caprolactone macromonomer (MM‐PCL) of different molecular weights. The linear analog, diacrylate end‐functionalized PCL (linear‐PCL), having comparable molecular weight of side chain of brush‐PCL is also synthesized. These polymers are thermally cured by a radical initiator in the presence of poly(ethylene glycol) diacrylate crosslinker. Thermal and linear viscoelastic properties as well as shape memory performance of the resulting PCL networks are investigated, and are significantly impacted by the PCL architecture. Therefore, our work highlights that tailoring macromolecular architecture is useful strategy to manipulate thermal, mechanical, and resulting shape memory properties. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3424–3433 相似文献
953.
954.
A formal total synthesis of the benzothiophene selective estrogen receptor modulator (SERM) desketoraloxifene and analogs has been accomplished from alkynes bearing electron-rich aromatic rings by electrophilic cyclization using I2. This approach affords oxygen-bearing 3-iodobenzo[b]thiophenes in excellent yields, which are easily further elaborated using a two-step approach involving Suzuki-Miyaura and Mitsunobu coupling reactions. 相似文献
955.
Hydrothermally prepared 100 nm-sized LiCoO2 with a plate morphology packed in a crucible resulted in 40 μm-sized particles that consisted of aggregated < 1 micron-sized particles after annealing at 900 °C for 3 h. In the condition where the optimized electrode pore volume was 20%, 4.1 g/cc of electrode density was obtained, which corresponded to 3 Wh/cc, which is the highest value among the cathode materials. Furthermore, the LiCoO2 showed excellent capacity retention of 78% after 290 cycles in a Li-ion cell under 7 C rate cycling. 相似文献
956.
957.
Baylis–Hillman acetates in EtOH were substituted by various nitrogen nucleophiles to give the corresponding trisubstituted alkenes in high yields. 相似文献
958.
959.
Yu Chen Hengchang Guo Wei Gong Luye Qin Hossein Aleyasin Rajiv R Ratan Sunghee Cho Jianxin Chen Shusen Xie 《中国光学快报(英文版)》2013,(1):59-66
In the past two decades, two-photon microscopy (TPM) transforms biomedicalresearch, allowing nondestructive high-resolution fluorescent molecular imaging and label-free imaging in vivo and in real time. Here we review the recent advances of TPM technologyincluding novel laser sources, new image acquisition paradiams, and microendoscopicimaging systems. Then, we survey the capabilities of TPM imagingof biological relevant molecules such as nicotinamideadenine dinucleotide (NADH), flavin adenine dinucleotide (FAD),and reactive oxygen species (ROS). Biomedical applications of TPM in neuroscience and cancer detection are demonstrated. 相似文献
960.
Triethylamine was very efficient in the dediazoniation of arenediazonium salt. The major product depended on the comparative molar ratio (r) of triethylamine to benzenediazonium salt. When r<0.5, anisole (ionic product) was a major, while benzene (radical product) was a major when r>1. 相似文献