全文获取类型
收费全文 | 2728篇 |
免费 | 199篇 |
国内免费 | 120篇 |
出版年
2023年 | 21篇 |
2022年 | 48篇 |
2021年 | 103篇 |
2020年 | 72篇 |
2019年 | 90篇 |
2018年 | 102篇 |
2017年 | 73篇 |
2016年 | 86篇 |
2015年 | 162篇 |
2014年 | 159篇 |
2013年 | 220篇 |
2012年 | 226篇 |
2011年 | 180篇 |
2010年 | 129篇 |
2009年 | 105篇 |
2008年 | 96篇 |
2007年 | 115篇 |
2006年 | 104篇 |
2005年 | 107篇 |
2004年 | 105篇 |
2003年 | 80篇 |
2002年 | 55篇 |
2001年 | 65篇 |
2000年 | 56篇 |
1999年 | 55篇 |
1998年 | 28篇 |
1997年 | 27篇 |
1996年 | 23篇 |
1995年 | 28篇 |
1994年 | 27篇 |
1993年 | 19篇 |
1992年 | 39篇 |
1991年 | 30篇 |
1990年 | 18篇 |
1989年 | 22篇 |
1988年 | 15篇 |
1987年 | 11篇 |
1986年 | 13篇 |
1985年 | 15篇 |
1984年 | 18篇 |
1983年 | 17篇 |
1982年 | 14篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 8篇 |
1974年 | 7篇 |
1971年 | 8篇 |
排序方式: 共有3047条查询结果,搜索用时 31 毫秒
61.
Two molecular forms of adenosine deaminase have been found in human tissues. The column gel filtration method has been used for the separation of the two enzyme forms. Routine separation and analysis of the enzyme forms based on the molecular size difference can be achieved by thin-layer gel filtration on Sephadex G-200 superfine gel. The thin-layer method has been found to be more rapid and efficient than the column method. Enzymes in crude preparations can be studied effectively with the thin-layer method. 相似文献
62.
Irradiated CBA anti-DBA/2 cells (106 cells/culture) suppressed the production of effector cells in cultures containing 107 unprimed CBA (responder) and 106 irradiated DBA/2 (stimulator) spleen cells per culture. The suppressive element was cellular and suppression was specific for the stimulating antigen. The suppressive activity resided in the cytotoxic cell population in that both suppressive and cytotoxic activities were found in cells of the same size range, predominantly in T-cells, were produced in response to similar doses of stimulator antigen, and were produced with the same time course following establishment of first sensitization cultures. Eventual suppression correlated with the cytotoxic activity introduced into second sensitization cultures by suppressor cells. The short-term cytotoxic activity and suppressor activity were both highly radioresistant. These studies indicate that the suppressor cells formed in an in vitro mixed lymphocyte culture are cytotoxic to stimulator cells. 相似文献
63.
64.
65.
66.
67.
68.
Yidi Sun Chen Li Shichao Pang Qianlan Yao Luonan Chen Yixue Li Rong Zeng 《基因组蛋白质组与生物信息学报(英文版)》2020,18(5):525-538
The estrogen receptor (ER)-negative breast cancer subtype is aggressive with few treatment options available. To identify specific prognostic factors for ER-negative breast cancer, this study included 705,729 and 1034 breast invasive cancer patients from the Surveillance, Epidemiology, and End Results (SEER) and The Cancer Genome Atlas (TCGA) databases, respectively. To identify key differential kinase–substrate node and edge biomarkers between ER-negative and ER-positive breast cancer patients, we adopted a network-based method using correlation coefficients between molecular pairs in the kinase regulatory network. Integrated analysis of the clinical and molecular data revealed the significant prognostic power of kinase–substrate node and edge features for both subtypes of breast cancer. Two promising kinase–substrate edge features, CSNK1A1–NFATC3 and SRC–OCLN, were identified for more accurate prognostic prediction in ER-negative breast cancer patients. 相似文献
69.
70.
Tao Jiang Hao Pang Jie An Pinjing Lu Yawei Feng Xi Liang Wei Zhong Zhong Lin Wang 《Liver Transplantation》2020,10(23)
Ocean wave energy is a promising renewable energy source, but harvesting such irregular, “random,” and mostly ultra‐low frequency energies is rather challenging due to technological limitations. Triboelectric nanogenerators (TENGs) provide a potential efficient technology for scavenging ocean wave energy. Here, a robust swing‐structured triboelectric nanogenerator (SS‐TENG) with high energy conversion efficiency for ultra‐low frequency water wave energy harvesting is reported. The swing structure inside the cylindrical TENG greatly elongates its operation time, accompanied with multiplied output frequency. The design of the air gap and flexible dielectric brushes enable mininized frictional resistance and sustainable triboelectric charges, leading to enhanced robustness and durability. The TENG performance is controlled by external triggering conditions, with a long swing time of 88 s and a high energy conversion efficiency, as well as undiminished performance after continuous triggering for 4 00 000 cycles. Furthermore, the SS‐TENG is demonstrated to effectively harvest water wave energy. Portable electronic devices are successfully powered for self‐powered sensing and environment monitoring. Due to the excellent performance of the distinctive mechanism and structure, the SS‐TENG in this work provides a good candidate for harvesting blue energy on a large scale. 相似文献