全文获取类型
收费全文 | 611611篇 |
免费 | 69331篇 |
国内免费 | 304篇 |
出版年
2018年 | 5277篇 |
2016年 | 7111篇 |
2015年 | 9870篇 |
2014年 | 11524篇 |
2013年 | 16470篇 |
2012年 | 18402篇 |
2011年 | 18542篇 |
2010年 | 12637篇 |
2009年 | 11380篇 |
2008年 | 16448篇 |
2007年 | 17182篇 |
2006年 | 15944篇 |
2005年 | 15491篇 |
2004年 | 15312篇 |
2003年 | 14760篇 |
2002年 | 14744篇 |
2001年 | 29406篇 |
2000年 | 29792篇 |
1999年 | 23394篇 |
1998年 | 7728篇 |
1997年 | 8020篇 |
1996年 | 7661篇 |
1995年 | 7224篇 |
1994年 | 7217篇 |
1993年 | 6956篇 |
1992年 | 19690篇 |
1991年 | 18914篇 |
1990年 | 18358篇 |
1989年 | 17774篇 |
1988年 | 16596篇 |
1987年 | 15603篇 |
1986年 | 14272篇 |
1985年 | 14328篇 |
1984年 | 11705篇 |
1983年 | 10219篇 |
1982年 | 7843篇 |
1981年 | 6929篇 |
1980年 | 6505篇 |
1979年 | 11470篇 |
1978年 | 8639篇 |
1977年 | 7970篇 |
1976年 | 7347篇 |
1975年 | 8181篇 |
1974年 | 8692篇 |
1973年 | 8678篇 |
1972年 | 8036篇 |
1971年 | 7224篇 |
1970年 | 6288篇 |
1969年 | 6039篇 |
1968年 | 5412篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Although phorbol 12-myristate 13-acetate (PMA) inhibits apoptosis and promotes the growth of some types of cells, it induces apoptosis in other cells. We evaluated the apoptotic effects of PMA on murine fibroblasts (L-929) that had been exposed to ultraviolet-B (UV-B) radiation at 312 nm, which promotes tumor cell growth. Exposure to PMA alone did not induce Fas, Fas-L, or apoptosis. Cells exposed to mild UV-B irradiation (80 J/m(2)) alone exhibited a slight expression of Fas and Fas-L 36 to 48 h after the exposure, and exhibited apoptosis as evidenced by DNA fragmentation 72 h after exposure. The addition of PMA (0.8 x 10(-5) to 3.2 x 10(-5) M) to the medium 24 h after the UV-B exposure markedly and dose-dependently enhanced these cell responses. Confluent untreated cells, cells cocultured with PMA, and cells cocultured with PMA for 24 h after the UV-B exposure consistently expressed mRNAs for wild-type p53, bcl-2, and ICE. Expression of c-myc mRNA was initially observed, but became undetectable in the cells cocultured for 24 h with a high concentration of PMA (3.2 x 10(-5) M) following UV-B exposure. Such cells subsequently exhibited the maximal apoptotic response. We conclude that mild exposure to UV-B altered murine fibroblast cells in such a way as to facilitate their death by apoptosis upon addition of PMA. 相似文献
52.
Argon laser surgery is an effective treatment for ectasias and congenital port-wine stains; however, its use in children under the age of 13 is controversial. This paper reviews 202 children under the age of 13 who underwent argon laser treatments for congenital port-wine stains, spider angiomas, epidermal nevi, and lentigines. The clinical characteristics of port-wine stains in 170 children are discussed. Good to excellent results (moderate to complete clearing) in port-wine stains were obtained in 60 percent of patients and seemed to correlate best with lack of blanchability on pressure. Hypertrophic scarring was seen in only 7 children, all of whom had undressed wounds; no significant scarring has been seen in any subsequent child who had maintained a dressed wound postoperatively. 相似文献
53.
54.
55.
56.
57.
Dahlgren K. V. O. 《Molecular & general genetics : MGG》1918,19(3):220
Ohne Zusammenfassung 相似文献
58.
59.
Besides vobtusine and vobtusine-lactone, deoxyvobtusine was isolated from the leaves of Voacanga grandifolia (Miq. Rolfe. Spectral and chemical evi 相似文献
60.