全文获取类型
收费全文 | 2543篇 |
免费 | 139篇 |
国内免费 | 1篇 |
出版年
2023年 | 2篇 |
2022年 | 12篇 |
2021年 | 24篇 |
2020年 | 17篇 |
2019年 | 25篇 |
2018年 | 31篇 |
2017年 | 35篇 |
2016年 | 56篇 |
2015年 | 88篇 |
2014年 | 105篇 |
2013年 | 188篇 |
2012年 | 161篇 |
2011年 | 153篇 |
2010年 | 100篇 |
2009年 | 116篇 |
2008年 | 156篇 |
2007年 | 163篇 |
2006年 | 169篇 |
2005年 | 167篇 |
2004年 | 153篇 |
2003年 | 169篇 |
2002年 | 194篇 |
2001年 | 28篇 |
2000年 | 18篇 |
1999年 | 16篇 |
1998年 | 34篇 |
1997年 | 27篇 |
1996年 | 23篇 |
1995年 | 18篇 |
1994年 | 21篇 |
1993年 | 26篇 |
1992年 | 26篇 |
1991年 | 20篇 |
1990年 | 15篇 |
1989年 | 11篇 |
1988年 | 13篇 |
1987年 | 5篇 |
1986年 | 12篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 10篇 |
1982年 | 22篇 |
1981年 | 11篇 |
1980年 | 10篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
排序方式: 共有2683条查询结果,搜索用时 15 毫秒
1.
2.
The effect of dimethyl sulfoxide (DMSO) on synthesis of basement membrane collagen in cultured smooth muscle cells was evaluated. DMSO promoted phenotypic modulation of cells from the synthetic state to the contractile state accompanied by formation of basement membranes. By immunofluorescence using monospecific antibody against type IV collagen, type IV collagen was identified not only in the cell cytoplasms but intensely along the cell surfaces in the cultures treated with DMSO for 7 days, as compared with untreated cultures. Electron microscopic immunohistochemistry revealed the presence of type IV collagen both in the basement membrane region and in the rough endoplasmic reticulum of DMSO-treated cells. Such an enhancement of type IV collagen synthesis appears to be expressed as a result of the phenotypic changes of smooth muscle cells to the contractile state modulated by DMSO. 相似文献
3.
We investigated the effects of near-infrared irradiation on the photoconversion of Chenopodium album water-soluble chlorophyll-binding protein (CaWSCP) in the presence of sodium hydrosulfite and found a further photoconversion from CP742 to CP763, a novel form of CaWSCP. Interestingly, one-third of the absorption peak at 668 nm was recovered in CP763, but re-irradiation under oxidative conditions eliminated the photo convertibility of CaWSCP. 相似文献
4.
5.
Yasushi Harada 《Journal of Ethology》1989,7(1):17-25
A theory on the evolution of human primary sex ratio is proposed. Effects of parental preference for sons, reflected in birth
control based on offspring sex ratio and female biased infanticide, on the evolution of primary sex ratio are analyzed. Both
are shown to select for female bias in primary sex ratio. The gene-culture coevolution of female infanticide and primary sex
ratio is also studied and it is shown that female infanticide develops more in societies in which the father plays a more
important role in the transmission of culture than the mother does. 相似文献
6.
7.
8.
Isamu Tanaka Akio Horie Joji Haratake Yasushi Kodama Kenzaburo Tsuchiya 《Biological trace element research》1988,16(1):19-26
There are few inhalation studies of nickel carcinogenesis. In this study, Wistar male rats were exposed to green nickel oxide
(NiO(G)) aerosols (mass median aerodynamic diameter, 0.6 μm) for 7 h/d, 5 d/wk for up to 12 mo. The average exposure concentration
was controlled at 0.3 and 1.2 mg/m3 during the exposure. For histopathological examination and measurement of the nickel concentration in rat organs, the rats
were sacrificed at 3, 6, and 12 mo of exposure and 8 mo clearance period following 12 mo of exposure.
The nickel content in rat lungs that was observed up to 2.6 mg after 12 mo exposure, was proportional to the exposure concentration
during the exposure. The clearance of the nickel from the lungs was very slow and the biological half time was determined
7.7 mo.
Although the rats were exposed continuously to NiO(G), for 12 mo and kept for 8 mo clearance period, there were no malignant
tumors in any of the exposed animals. 相似文献
9.
Masaki Fujimura Yasushi Miyake Kohhei Uotani Kazunori Kanamori Tamotsu Matsuda 《Prostaglandins & other lipid mediators》1988,35(3)
Effect of a thromboxane synthetase inhibitor (OKY-046) on bronchoconstriction induced by aerosol leukotriene C4 and histamine was studied in anesthetized, artificially ventilated guinea pigs in order to examine whether secondary release of thromboxane A2 is produced by aerosol leukotriene C4 or not. 0.01–1.0μg/ml of leukotriene C4 and 12.5–400μg/ml of histamine inhaled from ultrasonic nebulizer developed for small animals caused dose-dependent increase of pressure at airway opening (Pao) which is considered to be an index representing bronchial response. Pretreatment of the animals with intravenous OKY-046 (100mg/kg) significantly reduced the airway responses produced by inhalation of 0.1, 0.33 and 1.0μg/ml of leukotriene C4, while the pretreatment did not affect the histamine dose-response curve. Based on these findings and previous reports (6, 7), it is suggested that aerosol leukotriene C4 activates arachidonate cyclooxygenase pathway including thromboxane A2 synthesis and the released cyclooxygenase products have bronchodilating effect as a whole 相似文献
10.