全文获取类型
收费全文 | 7809篇 |
免费 | 873篇 |
国内免费 | 3篇 |
出版年
2021年 | 83篇 |
2020年 | 75篇 |
2019年 | 77篇 |
2018年 | 121篇 |
2017年 | 94篇 |
2016年 | 127篇 |
2015年 | 228篇 |
2014年 | 254篇 |
2013年 | 375篇 |
2012年 | 413篇 |
2011年 | 414篇 |
2010年 | 291篇 |
2009年 | 224篇 |
2008年 | 340篇 |
2007年 | 353篇 |
2006年 | 328篇 |
2005年 | 302篇 |
2004年 | 305篇 |
2003年 | 321篇 |
2002年 | 320篇 |
2001年 | 150篇 |
2000年 | 124篇 |
1999年 | 149篇 |
1998年 | 115篇 |
1997年 | 76篇 |
1996年 | 95篇 |
1995年 | 86篇 |
1994年 | 78篇 |
1993年 | 78篇 |
1992年 | 112篇 |
1991年 | 114篇 |
1990年 | 102篇 |
1989年 | 117篇 |
1988年 | 92篇 |
1987年 | 101篇 |
1986年 | 91篇 |
1985年 | 103篇 |
1984年 | 125篇 |
1983年 | 81篇 |
1982年 | 101篇 |
1981年 | 76篇 |
1980年 | 93篇 |
1979年 | 100篇 |
1978年 | 80篇 |
1977年 | 89篇 |
1976年 | 66篇 |
1975年 | 72篇 |
1974年 | 69篇 |
1973年 | 77篇 |
1972年 | 64篇 |
排序方式: 共有8685条查询结果,搜索用时 15 毫秒
21.
Walter G. Levine 《Life sciences》1973,13(6):723-732
The effects of 3-amino-1,2,4-triazole and phenobarbital, alone and in combination, on the metabolism and biliary excretion of 3,4-benzpyrene have been investigated in Wistar and Sprague-Dawley rats of both sexes. Although phenobarbital induced and aminotriazole inhibited metabolism, considerable variation with species and sex was observed. The effects of these drugs on liver weight, microsomal protein and bile flow also varied among these groups of rats. it is apparent that there was no quantitative relationship between the pattern of excretion of benzpyrene metabolites and bile flow, microsomal protein and liver weight. 相似文献
22.
Glutamine synthetase from Escherichia coli was inactivated by chemical modification with arginine-specific reagents (Colanduoni, J. A., and Villafranca, J. J. (1985) Biochem. Biophys. Res. Commun. 126, 412-418). E. coli glutamine synthetase was also a substrate for an erythrocyte NAD:arginine ADP-ribosyltransferase. Transfer of one ADP-ribosyl group/subunit of glutamine synthetase caused loss of both biosynthetic and gamma-glutamyltransferase activity. The ADP-ribose moiety was enzymatically removed by an erythrocyte ADP-ribosylarginine hydrolase, resulting in return of function. The site of ADP-ribosylation was arginine 172, determined by isolation of the ADP-ribosylated tryptic peptide. Arginine 172 lies in a central loop that extends into the core formed by the 12 subunits of the native enzyme. The central loop is important in anchoring subunits together to yield the spatial orientation required for catalytic activity. ADP-ribosylation may thus inactivate glutamine synthetase by disrupting the normal subunit alignment. Enzyme-catalyzed ADP-ribosylation may provide a simple, specific technique to probe the role of arginine residues in the structure and function of proteins. 相似文献
23.
Michiel L. Houben Marloes J. M. Olde Nordkamp Peter G. J. Nikkels Cornelis K. van der Ent Linde Meyaard Louis Bont 《PloS one》2013,8(12)
The soluble form of the inhibitory immune receptor leukocyte-Associated Ig-like Receptor-1 (sLAIR-1) is present in plasma, urine and synovial fluid and correlates to inflammation. We and others previously showed inflammatory protein expression in normal amniotic fluid at term. We hypothesized that sLAIR-1 is present in amniotic fluid during term parturition and is related to fetal lung function development. sLAIR-1 was detectable in all amniotic fluid samples (n=355) collected during term spontaneous deliveries. First, potential intra-uterine origins of amniotic fluid sLAIR-1 were explored. Although LAIR-1 was expressed on the surface of amniotic fluid neutrophils, LAIR-1 was not secreted upon ex vivo neutrophil stimulation with LPS, or PMA/ionomycin. Cord blood concentrations of sLAIR-1 were fourfold lower than and not related to amniotic fluid concentrations and placentas showed no or only sporadic LAIR-1 positive cells. Similarly, in post-mortem lung tissue of term neonates that died of non-pulmonary disorders LAIR-1 positive cells were absent or only sporadically present. In fetal urine samples, however, sLAIR-1 levels were even higher than in amniotic fluid and correlated with amniotic fluid sLAIR-1 concentrations. Second, the potential relevance of amniotic fluid sLAIR-1 was studied. sLAIR-1 concentrations had low correlation to amniotic fluid cytokines. We measured neonatal lung function in a convenient subset of 152 infants, using the single occlusion technique, at a median age of 34 days (IQR 30-39). The amniotic fluid concentration of sLAIR-1 was independently correlated to airway compliance (ρ=0.29, P=.001). Taken together, we show the consistent presence of sLAIR-1 in amniotic fluid, which originates from fetal urine. Concentrations of sLAIR-1 in amniotic fluid during term deliveries are independent from levels of other soluble immune mediators. The positive association between concentrations of amniotic fluid sLAIR-1 and neonatal lung compliance suggests that amniotic fluid sLAIR-1 may be useful as a novel independent marker of neonatal lung maturation. 相似文献
24.
Sarah Levine 《Culture, medicine and psychiatry》1980,4(2):151-165
Amongst the Gush of southwestern Kenya instances of rape are frequently reported; this was true also in the colonial period and yet it seems that those cases which come to the notice of the authorities are few compared with the numbers which actually occur. While certain features of the traditional culture seem to have encouraged violent sexual assault, because in a patrilocal society miscreants are likely to victimize their relatives, that is women who are sexually taboo, the crime is considered a sacrilegious matter to be dealt with in the family, not by the secular authorities. Given the sacrilegious nature of the act the Gush are convinced that such behavior is involuntary and that the criminal is not a criminal but an afflicted person, motivated by the malevolence of the ancestral spirits or of jealous neighbors and kin. The author uses case material to illustrate various aspects of the Gush belief system in regard to criminal behavior in general and rape in particular. 相似文献
25.
26.
27.
28.
29.
30.