全文获取类型
收费全文 | 1047篇 |
免费 | 55篇 |
出版年
2022年 | 5篇 |
2021年 | 10篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 10篇 |
2016年 | 24篇 |
2015年 | 19篇 |
2014年 | 30篇 |
2013年 | 80篇 |
2012年 | 77篇 |
2011年 | 57篇 |
2010年 | 43篇 |
2009年 | 47篇 |
2008年 | 60篇 |
2007年 | 59篇 |
2006年 | 63篇 |
2005年 | 64篇 |
2004年 | 45篇 |
2003年 | 51篇 |
2002年 | 63篇 |
2001年 | 13篇 |
2000年 | 11篇 |
1999年 | 14篇 |
1998年 | 9篇 |
1997年 | 12篇 |
1996年 | 17篇 |
1995年 | 14篇 |
1994年 | 12篇 |
1993年 | 6篇 |
1992年 | 15篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 9篇 |
1985年 | 15篇 |
1984年 | 10篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1977年 | 9篇 |
1976年 | 7篇 |
1975年 | 8篇 |
1974年 | 6篇 |
1973年 | 10篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1969年 | 3篇 |
排序方式: 共有1102条查询结果,搜索用时 15 毫秒
1.
2.
3.
We have cloned and sequenced the p53-encoding cDNA of Syrian hamster. The encoded product is 78% and 75% homologous to human and mouse p53, respectively. Immunoprecipitations of the cDNA-encoded protein by monoclonal antibodies specific for mammalian p53 confirmed the identity of the protein. 相似文献
4.
Early increases in the frequency of DNA initiations and of phospholipid synthesis discontinuities after nutritional shift-up in Escherichia coli 总被引:1,自引:0,他引:1
Cultures of Escherichia coli (strains ML30 and K12 AB1157), synchronized by repeated phosphate starvation, were submitted to nutritional shifts-up at various cell ages. The progression of the replication forks was assessed by DNA-DNA hybridization of pulse-labelled chromosomal DNA with plasmid DNA probes containing specific chromosomal sequences. The rate of phospholipid synthesis and its cyclic discontinuities were measured by continuous and pulse labelling with palmitate. The DNA-DNA hybridization experiments showed that a shift-up induces a burst of initiation from the oriC region. These hybridization results, taken together with older data from the literature, suggest that most DNA initiations belonging to this burst are not followed by complete replication. Following a shift-up, the rate of phospholipid synthesis is maintained for 13-20 min, depending on cell age at shift-up, then doubles. The new steady-state rate of phospholipid synthesis is reached through a series of three doublings, while the cell mass doubles approximately twice. This discrepancy brings the rate of phospholipid synthesis per mass unit to its steady-state postshift value. 相似文献
5.
Isolation and Characterization of Thermophilic Bacterial Strains with Inulinase Activity 总被引:6,自引:2,他引:4
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jean-Jacques Allais Gladys Hoyos-Lopez Sadok Kammoun Jacques C. Baratti 《Applied microbiology》1987,53(5):942-945
Nine bacterial strains growing on inulin as the sole carbon and energy source were isolated from soil samples by enrichment culture on a mineral medium. Four of the strains were thermophilic and belong to the genus Bacillus. The thermophilic strains synthesized a β-fructosidase that was active on both inulin and sucrose. The presence of inulin in the culture medium is necessary for enzyme synthesis. Most of the activity on inulin was recovered in the culture medium, and the enzyme was synthesized during cell growth. 相似文献
6.
Human elongation factor 1α: a polymorphic and conserved multigene family with multiple chromosomal localizations 总被引:1,自引:0,他引:1
7.
8.
G. Leclercq N. Legros M.J. Piccart 《The Journal of steroid biochemistry and molecular biology》1992,41(3-8):545-552
It is well known that MCF-7 cells, when incubated with hydroxytamoxifen (OH-Tam) loose their capacity to bind [3H]estradiol. By using Western blotting and [3H]tamoxifen aziridine labeling of KCl extracts from these cells we found that this loss in binding capacity was not associated with a disappearance of the estrogen receptor (ER) protein, an event known to occur after incubation with estradiol. Attempts to label under exchange conditions these ER molecules, which, on the basis of enzyme immunoassays appear to accumulate under OH-Tam treatment, were unsuccessful. Cell fractionation suggested that their origin is nuclear. Assessment of a few triphenylethylenic antiestrogens, as far as their inhibitory potency towards the in vitro MCF-7 cell growth is concerned, indicated a correlation between accumulation of these non-binding ER molecules and the antiestrogen antiproliferative action. However, we were unable to demonstrate absence of such an ER accumulation in two tamoxifen-resistant variants. Impaired folding of the ER protein or impaired phosphorylation of its hormone-binding domain are attractive hypotheses to account for these non-binding ER molecules. Whether these ER molecules have any physiological role, such as competition with the “normal” receptor molecules for the estrogen responsive elements on the DNA is unknown and deserves further study. 相似文献
9.
Eveline De Mdicis Jean Paquette Jean-Jacques Gauthier Dennis Shapcott 《Applied microbiology》1986,52(3):567-573
Magnesium and manganese contents were measured by atomic absorption spectrophotometry in bacteria of several halophilic levels, in Vibrio costicola, a moderately halophilic eubacterium growing in 1 M NaCl, Halobacterium volcanii, a halophilic archaebacterium growing in 2.5 M NaCl, Halobacterium cutirubrum, an extremely halophilic archaebacterium growing in 4 M NaCl, and Escherichia coli, a nonhalophilic eubacterium growing in 0.17 M NaCl. Magnesium and manganese contents varied with the growth phase, being maximal at the early log phase. Magnesium and manganese molalities in cell water were shown to increase with the halophilic character of the logarithmically growing bacteria, from 30 mmol of Mg per kg of cell water and 0.37 mmol of Mn per kg of cell water for E. coli to 102 mmol of Mg per kg of cell water and 1.6 mmol of Mn per kg of cell water for H. cutirubrum. The intracellular concentrations of manganese were determined independently by a radioactive tracer technique in V. costicola and H. volcanii. The values obtained by 54Mn loading represented about 70% of the values obtained by atomic absorption. The increase of magnesium and manganese contents associated with the halophilic character of the bacteria suggests that manganese and magnesium play a role in haloadaptation. 相似文献
10.
Platelet serotonin (5-HT) content and uptake were studied in male SHR and WKY at various ages. Blood was withdrawn from the carotid artery under anesthesia and 5-HT levels determined from platelet rich plasma (PRP) using a HPLC technique coupled with an electrochemical detection method. Platelet 5-HT uptake was studied by incubating PRP at 37 degrees C for 10 sec with increasing concentrations of 3H-5HT. Lineweaver- Burk plots of 3H-5HT uptake were linear suggesting simple Michaelis- Menten uptake kinetics. The SHR had more platelets than age-matched controls and consequently a higher blood circulating pool of 5-HT. Nevertheless, the 5-HT platelet levels were similar to those of their age-matched rats. The 5 week-old SHR and WKY had greater numbers of platelets and higher 5-HT platelet levels than the older rats of both strains. The affinity constants (Km) and the maximal velocities (Vmax) of platelet 5-HT uptake did not differ significantly between the 12 week- and the 6 month-old SHR and WKY. These data suggest that the SHR do not show the same impairment in platelet 5-HT metabolism as observed in essential hypertension in man. 相似文献