全文获取类型
收费全文 | 2125篇 |
免费 | 74篇 |
国内免费 | 15篇 |
专业分类
化学 | 1704篇 |
晶体学 | 17篇 |
力学 | 26篇 |
数学 | 115篇 |
物理学 | 352篇 |
出版年
2022年 | 14篇 |
2021年 | 19篇 |
2020年 | 13篇 |
2019年 | 36篇 |
2018年 | 31篇 |
2017年 | 9篇 |
2016年 | 32篇 |
2015年 | 46篇 |
2014年 | 50篇 |
2013年 | 128篇 |
2012年 | 121篇 |
2011年 | 119篇 |
2010年 | 79篇 |
2009年 | 74篇 |
2008年 | 124篇 |
2007年 | 138篇 |
2006年 | 121篇 |
2005年 | 123篇 |
2004年 | 113篇 |
2003年 | 81篇 |
2002年 | 90篇 |
2001年 | 36篇 |
2000年 | 42篇 |
1999年 | 24篇 |
1998年 | 18篇 |
1997年 | 19篇 |
1996年 | 23篇 |
1994年 | 11篇 |
1993年 | 16篇 |
1992年 | 22篇 |
1991年 | 23篇 |
1990年 | 23篇 |
1989年 | 18篇 |
1988年 | 15篇 |
1987年 | 17篇 |
1986年 | 12篇 |
1985年 | 39篇 |
1984年 | 31篇 |
1983年 | 14篇 |
1982年 | 30篇 |
1981年 | 29篇 |
1980年 | 28篇 |
1979年 | 19篇 |
1978年 | 19篇 |
1977年 | 20篇 |
1976年 | 15篇 |
1975年 | 10篇 |
1974年 | 13篇 |
1973年 | 18篇 |
1968年 | 8篇 |
排序方式: 共有2214条查询结果,搜索用时 14 毫秒
1.
2.
K Kawasaki T Tsuji K Hirase M Miyano Y Imoto M Iwamoto 《Chemical & pharmaceutical bulletin》1991,39(3):584-589
N-Terminal tripeptide analogs of fibrin alpha-chain were synthesized and their inhibitory effect on fibrinogen/thrombin clotting was examined. A new water-soluble active ester, 3-pyridinium ester, was used for the synthesis. Among the synthetic peptides, H-Gly-Pro-Arg-hexamethyleneimine exhibited the highest inhibitory effect on fibrinogen-thrombin clotting. 相似文献
3.
A Necessary and Sufficient Condition for the Existence of a Heterochromatic Spanning Tree in a Graph
Kazuhiro Suzuki 《Graphs and Combinatorics》2006,22(2):261-269
We prove the following theorem. An edge-colored (not necessary to be proper) connected graph G of order n has a heterochromatic spanning tree if and only if for any r colors (1≤r≤n−2), the removal of all the edges colored with these r colors from G results in a graph having at most r+1 components, where a heterochromatic spanning tree is a spanning tree whose edges have distinct colors. 相似文献
4.
We studied the hydrolysis of a neuropeptide kyotorphin (L-Tyr-L-Arg) by an enkephalin-degrading aminopeptidase purified from cytosol of rat brain in vitro. The purified enzyme was homogeneous as judged by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE), gel filtration and isoelectric focusing. The aminopeptidase with an apparent molecular weight (Mr) = 98000 catalyzed the hydrolysis of Leu- and Met-enkephalins with Km values of 125 and 142 microM, respectively. The enzyme activity was inhibited by bestatin, amastatin and puromycin but not by pepstatin, leupeptin and phenylmethanesulfonyl fluoride (PMSF). Kyotorphin was degraded by the aminopeptidase at pH 7.0, and the Vmax and Km values were 9.2 mumol/min/mg protein and 95 microM, respectively. The Km value for kyotorphin was compatible to those for Leu- and Met-enkephalins. Taken together, these results suggest a possible involvement of the enkephalin-degrading aminopeptidase in cytosolic degradation of kyotorphin in neuronal cells of rat brain. 相似文献
5.
Toshiro Watanabe Tapan Kumar Mazumder Shiro Nagai Keisuke Tsuji Shigeru Terabe 《Analytical sciences》2003,19(1):159-161
A micellar electrokinetic chromatography (MEKC) method was developed for estimating the angiotensin-I converting enzyme (ACE) inhibitory activity by separating the hippuric acid liberated in the ACE reaction mixture in the presence of an inhibitor, captopril. The hippuric acid was successfully separated and detected by MEKC with a 25 mM sodium dodecyl sulfate solution in a 25 mM phosphate-50 mM borate buffer at pH 7.0; the total analysis took about 5 min. A good linear relationship was observed between the inhibitor and the peak area of hippuric acid release. No significant difference in the ACE inhibitory activity (IC50) of captopril (an antihypertensive medicine) or autolyzed-mushrooms (functional foods) was observed between the conventional method and the MEKC method. The MEKC method was found to be a useful technique for a rapid assay of the ACE inhibitory activity. 相似文献
6.
7.
The self-restoration properties in VWP networks are investigated with optimization about spare wavelength by simulations. Rapid restoration can be achieved by selection of rerouting path with long delay and no delay-limitation for new routes. 相似文献
8.
Endoscopic Observation of Tissue by Narrowband Illumination 总被引:6,自引:0,他引:6
Kazuhiro Gono Kenji Yamazaki Nobuyuki Doguchi Tetsuo Nonami Takashi Obi Masahiro Yamaguchi Nagaaki Ohyama Hirohisa Machida Yasushi Sano Shigeaki Yoshida Yasuo Hamamoto Takao Endo 《Optical Review》2003,10(4):211-215
We propose a new illumination method for a medical endoscope: narrow band imaging (NBI), in which the spectral bandwidth of the filtered light is narrowed. To confirm how the spectral specifications of the filtered light influence a reproduced image, an experiment was conducted observing the endoscopic images of the back mucosa of a human tongue. In addition, the effect of NBI on endoscopic images was investigated through preliminary clinical tests in colonoscopy and upper gastrointestinal endoscopy. It has been shown that NBI can enhance the capillary pattern and the crypt pattern on the mucosa. These patterns are useful features for diagnosing an early cancer. 相似文献
9.