全文获取类型
收费全文 | 6067篇 |
免费 | 385篇 |
出版年
2021年 | 82篇 |
2020年 | 37篇 |
2019年 | 61篇 |
2018年 | 91篇 |
2017年 | 71篇 |
2016年 | 111篇 |
2015年 | 156篇 |
2014年 | 208篇 |
2013年 | 353篇 |
2012年 | 320篇 |
2011年 | 325篇 |
2010年 | 203篇 |
2009年 | 178篇 |
2008年 | 288篇 |
2007年 | 324篇 |
2006年 | 290篇 |
2005年 | 279篇 |
2004年 | 289篇 |
2003年 | 281篇 |
2002年 | 269篇 |
2001年 | 199篇 |
2000年 | 210篇 |
1999年 | 164篇 |
1998年 | 94篇 |
1997年 | 75篇 |
1996年 | 71篇 |
1995年 | 57篇 |
1994年 | 48篇 |
1993年 | 42篇 |
1992年 | 88篇 |
1991年 | 108篇 |
1990年 | 99篇 |
1989年 | 105篇 |
1988年 | 81篇 |
1987年 | 85篇 |
1986年 | 78篇 |
1985年 | 80篇 |
1984年 | 65篇 |
1983年 | 65篇 |
1982年 | 42篇 |
1981年 | 26篇 |
1980年 | 18篇 |
1979年 | 41篇 |
1978年 | 27篇 |
1977年 | 32篇 |
1976年 | 22篇 |
1975年 | 23篇 |
1974年 | 24篇 |
1973年 | 30篇 |
1970年 | 17篇 |
排序方式: 共有6452条查询结果,搜索用时 15 毫秒
1.
Y Tani I Ohkubo S Higashiyama M Kunimatsu M Sasaki 《Comparative biochemistry and physiology. B, Comparative biochemistry》1987,88(2):429-441
1. High mol. wt kininogen (HMW kininogen) was purified to a homogeneous state from porcine plasma. 2. The protein exhibited a strong inhibitory activity for thiol proteinases such as ficin, papain and calpain I, whereas it did not inhibit serine proteinases, trypsin and chymotrypsin. 3. The mol. wt, isoelectric point, amino acid and carbohydrate compositions, stabilities to temperature and pH, kinetic constants, and immunological properties of the porcine HMW kininogen were determined and compared with those of human HMW kininogen. 相似文献
2.
Masaki Saito Hiroyuki Tanaka Masako Sasaki Hitoshi Kurose Norimichi Nakahata 《Cellular signalling》2010,22(1):41-46
The physiological role of the thromboxane A2 (TXA2) receptor expressed on glial cells remains unclear. We previously reported that 1321N1 human astrocytoma cells pretreated with dibutyryl cyclic AMP (dbcAMP) became swollen in response to U46619, a TXA2 analogue. In the present study, we examined the detailed mechanisms of TXA2 receptor-mediated cell swelling in 1321N1 cells. The cell swelling caused by U46619 was suppressed by expression of p115-RGS, an inhibitory peptide of Gα12/13 pathway and C3 toxin, an inhibitory protein for RhoA. The swelling was also inhibited by treatment with Y27632, a Rho kinase inhibitor and 5-(ethyl-N-isopropyl)amiloride (EIPA), a Na+/H+-exchanger inhibitor. Furthermore, cell swelling was suppressed by the pretreatment with aquaporin inhibitors mercury chloride or phloretin in a concentration-dependent manner, suggesting that aquaporins are involved in U46619-induced 1321N1 cell swelling. In fact, U46619 caused [3H]H2O influx into the cells, which was inhibited by p115-RGS, C3 toxin, EIPA, mercury chloride and phloretin. This is the first report that the TXA2 receptor mediates water influx through aquaporins in astrocytoma cells via TXA2 receptor-mediated activation of Gα12/13, Rho A, Rho kinase and Na+/H+-exchanger. 相似文献
3.
4.
Oxidation of thymine with O2 was promoted by copper(I) ion generated from reaction of L-ascorbic acid (AA) with copper (II) ion. The main oxidation products were thymine glycol (TG) and N-formyl-N'-pyruvylurea (FPU). At higher concentration of O2, formation of FPU was favored, while TG was dominant at higher Cu(II) ion and lower O2 concentrations. Reaction mechanism involving hydroxy thyminyl radical was proposed. 相似文献
5.
6.
Several modification of the arrangements of α-helical molecules were found in the solid films of poly (γ-ethyl-L -glutamate), depending on the casting solvent and the temperature. The helical conformation is somewhat looser than the normal 18-residue, 5-turn α-helix. Using x-ray diffraction, the types of molecular arrangements were classified into tetragonal, pseudohexagonal, and hexagonal ones. Tetragonal packing was observed in the filmm (form T) prepared by casting the solution in trifluorethanol or dichlorethane. The sample obtained from chloroform solution is a well-ordered, pseudohexagonal modification (form I). Forms I and T change into a poorly crystalline form III by annealing at temperatures above 130° C. It is particularly noteworthy that the less-ordered form III exhibits a thermoreversible transition around 110°C into a well-ordered form H with the hexagonal molecular packing. 相似文献
7.
Keisuke Hanaki Tomonori Matsuo Michihiko Nagase 《Biotechnology and bioengineering》1981,23(7):1591-1610
The inhibitory effect of long-chain fatty acids on the anaerobic digestion process was examined in batch experiments using synthetic substrates. The addition of long-chain fatty acids caused the appearance of the appearance of the lag period in the methane production from acetate and in the degradation of both long-chain fatty acids and n-butyrate. Methane production from hydrogen proceeded without lag period although its rate was lowered. Fermentation of glucose was not inhibited. Neutral fat in the whole milk was easily hydrolyzed to long-chain fatty acids, which brought about the inhibition. The addition of calcium chloride reduced the inhibitory effect of long-chain fatty but it did not do so after the culture had been exposed to long-chain fatty acids for more than several hours. The addition of calcium carbonate could not reduce the inhibition because of its insolubility. 相似文献
8.
Stability increments of 3' dangling ends on the core helices AUGCAU at various Na+ concentrations are reported. The results show that all 3' dangling ends except 3'U dangling at low Na+ concentrations can stabilize the helix and this stabilization is very sequence dependent. 相似文献
9.
Sleep and Biological Rhythms - 相似文献
10.