全文获取类型
收费全文 | 6616篇 |
免费 | 663篇 |
专业分类
7279篇 |
出版年
2021年 | 67篇 |
2020年 | 50篇 |
2019年 | 56篇 |
2018年 | 74篇 |
2017年 | 76篇 |
2016年 | 99篇 |
2015年 | 221篇 |
2014年 | 226篇 |
2013年 | 263篇 |
2012年 | 306篇 |
2011年 | 332篇 |
2010年 | 218篇 |
2009年 | 224篇 |
2008年 | 282篇 |
2007年 | 321篇 |
2006年 | 265篇 |
2005年 | 279篇 |
2004年 | 259篇 |
2003年 | 300篇 |
2002年 | 263篇 |
2001年 | 130篇 |
2000年 | 102篇 |
1999年 | 114篇 |
1998年 | 90篇 |
1997年 | 64篇 |
1996年 | 69篇 |
1995年 | 75篇 |
1994年 | 72篇 |
1993年 | 71篇 |
1992年 | 92篇 |
1991年 | 110篇 |
1990年 | 85篇 |
1989年 | 115篇 |
1988年 | 93篇 |
1987年 | 97篇 |
1986年 | 75篇 |
1985年 | 78篇 |
1984年 | 93篇 |
1983年 | 76篇 |
1982年 | 71篇 |
1981年 | 65篇 |
1980年 | 73篇 |
1979年 | 78篇 |
1978年 | 87篇 |
1977年 | 52篇 |
1976年 | 58篇 |
1974年 | 69篇 |
1973年 | 90篇 |
1972年 | 52篇 |
1971年 | 56篇 |
排序方式: 共有7279条查询结果,搜索用时 0 毫秒
1.
Malcolm Aitken 《BMJ (Clinical research ed.)》1999,319(7207):401
2.
W D Stein 《Biochimica et biophysica acta》1986,856(3):634-639
A theoretical analysis is made of the possible quantitative relationships between the transport resistances that characterise membrane carrier systems. It is shown that there exist only five possible patterns in which to rank the four transport resistances. Symbolising these as A, B, C and D, the five possible patterns are (i) A = B = C = D; (ii) A = B much greater than C, D; (iii) A = B much greater than C = D; (iv) A = B = 2C = 2D; (v) A = 2B = 2C much greater than D. A survey of the available experimental data shows that pattern (ii) is the most prevalent, pattern (v) is often found and pattern (iii) has been identified. None of the ten transport systems so far analysed experimentally failed to fit one of the predicted patterns. 相似文献
3.
Markers for trans-Golgi Membranes and the Intermediate Compartment Localize to Induced Membranes with Distinct Replication Functions in Flavivirus-Infected Cells 下载免费PDF全文
Replication of the flavivirus Kunjin virus is associated with virus-induced membrane structures within the cytoplasm of infected cells; these membranes appear as packets of vesicles associated with the sites of viral RNA synthesis and as convoluted membranes (CM) and paracrystalline arrays (PC) containing the components of the virus-specified protease (E. G. Westaway, J. M. Mackenzie, M. T. Kenney, M. K. Jones, and A. A. Khromykh, J. Virol. 71:6650-6661, 1997). To determine the cellular origins of these membrane structures, we compared the immunolabelling patterns of several cell markers in relation to these sites by immunofluorescence and immunoelectron microscopy. A marker for the trans-Golgi membranes and the trans-Golgi network, 1,4-galactosyltransferase (GalT), was redistributed to large foci in the cytoplasm of Kunjin virus-infected cells, partially coincident with immunofluorescent foci associated with the putative sites of viral RNA synthesis. As determined by immunoelectron microscopy, the induced vesicle packets contained GalT, whereas the CM and PC contained a specific protein marker for the intermediate compartment (ERGIC53). A further indicator of the role of cellular organelles in their biogenesis was the observation that the Golgi apparatus-disrupting agent brefeldin A prevented further development of immunofluorescent foci of induced membranes if added before the end of the latent period but that once formed, these membrane foci were resistant to brefeldin A dispersion. Reticulum membranes emanating from the induced CM and PC were also labelled with the rough endoplasmic reticulum marker anti-protein disulfide isomerase and were obviously redistributed during infection. This is the first report identifying trans-Golgi membranes and the intermediate compartment as the apparent sources of the flavivirus-induced membranes involved in events of replication. 相似文献
4.
Lincoln D Stein 《Genome biology》2010,11(5):207
With DNA sequencing now getting cheaper more quickly than data storage or computation, the time may have come for genome informatics
to migrate to the cloud. 相似文献
5.
6.
Olsvik Ørjan Myhre Stein Berdal Bjorn P. Fossum Kåre 《Acta veterinaria Scandinavica》1982,23(2):204-210
Enterotoxigenic reference strains of Staphylococcus aureus were cultivated in sterile whole and skim milk for 18 h at 37°G. Staphylococcal enterotoxin A, B, and C were detected directly in the milk by an enzyme linked immunosorbent assay (ELISA), sensitive down to 1 ng/ml. Enterotoxins in the range of 1 ng–20 µg/ml milk were detected without any concentration or extraction. Skim and whole milk were almost identical as medium for enterotoxin production. 相似文献
7.
8.
9.
10.
To determine whether histone genes are coordinately regulated, histone mRNA concentrations were measured in exponentially growing L6 myoblasts, S-phase synchronized myoblasts and in differentiating myoblasts. The levels of various histone mRNA subspecies declined rapidly and coordinately once myoblasts were given the signal to differentiate. mRNA levels were reduced on average to 1-5% of the amount observed in exponentially growing cells by 48 h after the signal to differentiate. The reductions occurred in concert with the cessation of DNA synthesis as the cells differentiated. Inhibition of DNA synthesis by treating myoblasts with Ara-C or hydroxyurea resulted in a histone mRNA half-life of 10-13 min for each of the histones examined. One example of non-coordinate regulation was observed however among the H4 mRNA subspecies in S-phase synchronized cells. The levels of two major subspecies of H4 mRNA increased coordinately in S-phase compared to levels observed in cells growing exponentially. A third subspecies of H4 mRNA on the other hand was found to decline by 50%. These studies suggest that the majority of histone mRNA subspecies are under coordinate control, although one exception has been noted among the subspecies of histone H4. 相似文献