全文获取类型
收费全文 | 9287篇 |
免费 | 411篇 |
国内免费 | 61篇 |
专业分类
化学 | 6390篇 |
晶体学 | 93篇 |
力学 | 279篇 |
数学 | 808篇 |
物理学 | 2189篇 |
出版年
2023年 | 54篇 |
2022年 | 190篇 |
2021年 | 226篇 |
2020年 | 178篇 |
2019年 | 172篇 |
2018年 | 172篇 |
2017年 | 144篇 |
2016年 | 296篇 |
2015年 | 269篇 |
2014年 | 354篇 |
2013年 | 596篇 |
2012年 | 743篇 |
2011年 | 823篇 |
2010年 | 469篇 |
2009年 | 385篇 |
2008年 | 616篇 |
2007年 | 580篇 |
2006年 | 512篇 |
2005年 | 473篇 |
2004年 | 408篇 |
2003年 | 325篇 |
2002年 | 326篇 |
2001年 | 216篇 |
2000年 | 177篇 |
1999年 | 129篇 |
1998年 | 69篇 |
1997年 | 79篇 |
1996年 | 95篇 |
1995年 | 80篇 |
1994年 | 75篇 |
1993年 | 57篇 |
1992年 | 60篇 |
1991年 | 47篇 |
1990年 | 51篇 |
1989年 | 34篇 |
1988年 | 26篇 |
1987年 | 12篇 |
1986年 | 10篇 |
1985年 | 26篇 |
1984年 | 18篇 |
1983年 | 17篇 |
1982年 | 18篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1979年 | 13篇 |
1978年 | 16篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1975年 | 10篇 |
1972年 | 9篇 |
排序方式: 共有9759条查询结果,搜索用时 15 毫秒
991.
992.
KNa[CoIII(OH)7{Mo6O17}] ·8H2O is obtained by ion‐exchange from a solution of K3 [Co(μ3‐OH)6Mo6O18] ·7H2O at ≈pH 1.4 using Amberlite IR120 ion exchange resin followed by concentrating the solution in a hot water bath. 相似文献
993.
Jong Eel Park Kyeong Wan Woo Sang Un Choi Je Hyun Lee Kang Ro Lee 《Helvetica chimica acta》2014,97(1):56-63
Two new spirostane‐steroidal saponins, bletilnoside A ( 1 ) and bletilnoside B ( 2 ), together with five known compounds, 3 – 7 , were isolated from the roots of Bletilla striata (Thunb .) Reichb . F. The structures of the new compounds were determined based on their 1D‐ and 2D‐NMR spectral data. The isolated compounds 1 – 7 were tested for cytotoxicity against four human tumor cells (A549, SK‐OV‐3, SK‐MEL‐2, and HCT15) in vitro using a sulforhodamin B bioassay, and compounds 1, 2 , and 5 showed significant cytotoxicities against all tested tumor cell lines with IC50 values ranging from 3.98±0.16 to 12.10±0.40 μM . 相似文献
994.
995.
Kyoungmi Hwang Kyungsik Lee Chungmok Lee Sungsoo Park 《The Journal of the Operational Research Society》2015,66(3):434-449
We propose two multi-class classification methods using a signomial function. Each of these methods directly constructs a multi-class classifier by solving a single optimization problem. Since the number of possible signomial terms is extremely large, we propose a column generation method that iteratively generates good signomial terms. Both of these methods obtain better or comparable classification accuracies than existing methods and also provide more sparse classifiers. 相似文献
996.
Yong Kyun Sim Suhyun Jung Jung Yun LimJuhyun Kim Seong-Ho KimBong Keun Song Bum Tae KimHyuk Lee Seongsoon Park 《Tetrahedron letters》2011,52(9):1041-1043
A facile process was developed to manufacture biocatalyst-conjugated magnetic nanobeads, which afford no loss of the intrinsic activity and enantioselectivity of biocatalysts. Up to 90% of their activities remained after six-time recycling in aqueous media. 相似文献
997.
998.
999.
1000.
Gye-Nam Kim Suk-Chol Lee Dong-Bin Shon Hye-Min Park Wang-Kyu Choi Jei-Kwon Moon 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(1):121-128
For the disposal of the high efficiency particulate air (HEPA) glass filter to environment, the glass fiber should be leached
to lower its radioactive concentration. To derive the optimum method for removal of Co and Cs from HEPA glass fiber, four
methods were applied in this study. Results of electrochemical leaching of glass fiber by 4.0 M HNO3–0.1 M Ce(IV) solution showed that the removal efficiency of 134Cs, 137Cs, and 60Cs from glass fiber after 5 h was 96.4, 93.6, and 93.8%, respectively. Results by 5 wt% NaOH solution showed that the removal
efficiency of 134Cs, 137Cs, and 60Cs after 30 h was 81.7, 82.1, and 10.0%, respectively. Results by repeat 2.0 M HNO3 solution showed that the removal efficiencies of 134Cs, 137Cs, and 60Cs after 2 h of three repetitions were 96.2, 99.4, and 99.1%, respectively. Finally, results by repeat 4.0 M HNO3 solution showed that the removal efficiencies of 134Cs, 137Cs, and 60Cs after 4 h of three repetitions were 100, 99.9, and 99.9%, respectively, and their radioactivities were below 0.1 Bq/g.
Therefore, the chemical leaching method by 4.0 M HNO3 solution was considered as an optimum one for removal of cesium and cobalt from HEPA glass fiber for self disposal. Also
the removal efficiencies of 60Co, 134Cs, and 137Cs from the waste-solution after its precipitation-filtration treatment for reuse of 4.0 M HNO3 waste-solution were 88.0, 95.0, and 99.8%. 相似文献