全文获取类型
收费全文 | 15478篇 |
免费 | 1284篇 |
国内免费 | 14篇 |
出版年
2022年 | 107篇 |
2021年 | 251篇 |
2020年 | 149篇 |
2019年 | 163篇 |
2018年 | 207篇 |
2017年 | 183篇 |
2016年 | 338篇 |
2015年 | 573篇 |
2014年 | 594篇 |
2013年 | 724篇 |
2012年 | 971篇 |
2011年 | 940篇 |
2010年 | 602篇 |
2009年 | 519篇 |
2008年 | 740篇 |
2007年 | 788篇 |
2006年 | 710篇 |
2005年 | 641篇 |
2004年 | 588篇 |
2003年 | 612篇 |
2002年 | 567篇 |
2001年 | 301篇 |
2000年 | 247篇 |
1999年 | 282篇 |
1998年 | 169篇 |
1997年 | 140篇 |
1996年 | 140篇 |
1995年 | 148篇 |
1994年 | 118篇 |
1993年 | 133篇 |
1992年 | 208篇 |
1991年 | 182篇 |
1990年 | 152篇 |
1989年 | 155篇 |
1988年 | 172篇 |
1987年 | 132篇 |
1986年 | 124篇 |
1985年 | 140篇 |
1984年 | 149篇 |
1983年 | 117篇 |
1982年 | 111篇 |
1981年 | 101篇 |
1980年 | 92篇 |
1979年 | 107篇 |
1978年 | 102篇 |
1977年 | 97篇 |
1976年 | 79篇 |
1974年 | 104篇 |
1973年 | 72篇 |
1972年 | 71篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
81.
Monique Aumailley Karlheinz Mann Helga von der Mark Rupert Timpl 《Experimental cell research》1989,181(2)
Twelve of sixteen different cell types including fibroblasts and tumor cells were able to attach and spread on substrates of pepsin-solubilized or intact collagen VI, and on its triple helical domain. Attachment and spreading were independent of soluble mediator proteins (fibronectin, laminin) and collagen VI was distinct from collagens I, IV and V in the cells with which it interacted. Many of the same cells bound and spread on substrates prepared from unfolded α2(VI) and α3(VI) chains but not on the α1(VI) chain. The interactions with the chains were inhibited by low concentrations (10–100 μM) of synthetic RGDS and RGDT but not RGES peptides while the binding of cells to pepsin-solubilized collagen VI was more than 20-fold less sensitive to these peptides. The data incidate that cells have the ability to bind to collagen VI in a specific manner suggesting a similar function for collagen VI in situ. 相似文献
82.
Cleavage-site motifs in mitochondrial targeting peptides 总被引:18,自引:0,他引:18
Although mitochondrial targeting peptides lack a common consensus sequence, a certain bias in the positional distribution of amino acids has recently been found. These patterns seem to be associated with cleavage of the precursor proteins by matrix processing proteases. We have extended the previous studies and found new sequence motifs that are conserved within subgroups of mitochondrial targeting peptides. These motifs have certain common themes, indicating that they are associated with cleavage by one single protease. Two of the conserved patterns have a high predictive value, but even for sequences that do not possess these patterns, a fairly accurate prediction of the cleavage site is shown to be possible. We also suggest that a well-conserved RXY decreases (S/A) pattern may be used to engineer efficiently recognized cleavage sites into uncleaved or artificial mitochondrial targeting peptides. 相似文献
83.
84.
85.
86.
Mannose 6-phosphate/insulin-like growth factor II-binding proteins in human serum and urine. Their relation to the mannose 6-phosphate/insulin-like growth factor II receptor. 总被引:5,自引:0,他引:5
下载免费PDF全文
![点击此处可从《The Biochemical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
C Causin A Waheed T Braulke U Junghans P Maly R E Humbel K von Figura 《The Biochemical journal》1988,252(3):795-799
Human serum and urine contain polypeptides which bind mannose 6-phosphate (M6P) and insulin-like growth factor II (IGF II) and crossreact with antibodies against the M6P/IGF II receptor. These polypeptides are considered to be fragments of the M6P/IGF II receptor. The major Mr approx. 205,000 fragment in serum and urine is about 10 kDa smaller in size than the membrane-associated receptor and is accompanied by minor forms with Mr values ranging from 104,000 to 180,000. The presence of receptor fragments in biological fluids indicates that shedding is one of the mechanisms contributing to the turnover of the M6P/IGF II receptor and that receptor fragments are part of the heterogenous group of serum proteins whic bind IGF II. 相似文献
87.
Neonatal screening for congenital adrenal hyperplasia using 17-hydroxyprogesterone assay in filter paper blood spots 总被引:1,自引:0,他引:1
A Larsson L Hagenfeldt U von D?beln T Curstedt J Gustafsson E Svensson 《Hormone research》1988,30(6):235-240
Screening of infants for congenital adrenal hyperplasia (CAH) using filter paper blood samples collected on the 5th day of life was performed with a radioimmunoassay for 17-hydroxyprogesterone without extraction with organic solvents. A total of 153,000 newborns were screened and 12 cases of CAH were detected (1:12,800). With recall levels related to gestational age, the recall rate could be lowered to 0.05%. 相似文献
88.
Corinne Vander Wauven Alfred Jann Dieter Haas Thomas Leisinger Victor Stalon 《Archives of microbiology》1988,150(4):400-404
Most Pseudomonas aeruginosa PAO mutants which were unable to utilize l-arginine as the sole carbon and nitrogen source (aru mutants) under aerobic conditions were also affected in l-ornithine utilization. These aru mutants were impaired in one or several enzymes involved in the conversion of N2-succinylornithine to glutamate and succinate, indicating that the latter steps of the arginine succinyltransferase pathway can be used for ornithine catabolism. Addition of aminooxyacetate, an inhibitor of the N2-succinylornithine 5-aminotransferase, to resting cells of P. aeruginosa in ornithine medium led to the accumulation of N2-succinylornithine. In crude extracts of P. aeruginosa an ornithine succinyltransferase (l-ornithine:succinyl-CoA N2-succinyltransferase) activity could be detected. An aru mutant having reduced arginine succinyltransferase activity also had correspondingly low levels of ornithine succinyltransferase. Thus, in P. aeruginosa, these two activities might be due to the same enzyme, which initiates aerobic arginine and ornithine catabolism.Abbreviations OAT
ornithine 5-aminotransferase
- SOAT
N2-succinylornithine 5-aminotransferase
- Oru
ornithine utilization
- Aru
arginine utilization 相似文献
89.
Dr. Teresa I. Mercado Patricia Strickler Kenner C. Rice Victor J. Ferrans 《Current microbiology》1988,16(4):179-183
Studies on the purification of an antitrypanosomal factor (ATF-II) obtained fromPseudomonas fluorescens disclosed that high-pressure liquid chromatography (HPLC) with a Rad-pak porasil (10 silica) column and a GPC-60 Å column was an efficient procedure for the separation of the active components. Extraction of the factor with absolute ethanol prior to elution significantly enhanced the lytic activity of the HPLC eluates, as shown by marked pathologic changes followed by lysis in bioassays performed withTrypanosoma equiperdum. HPLC provided an increase of purification 30 times that obtained with gel filtration of the crude bacterial product. The lipopolysaccharide content of the purified fractions was markedly reduced and indicated an additional advantage for further in vivo tests in experimental infections withT. cruzi. 相似文献
90.
Site-specific endonucleolytic cleavages and the regulation of stability of E. coli ompA mRNA 总被引:53,自引:0,他引:53
The stability of ompA mRNA is growth-rate dependent. We show that the 5' noncoding region of this mRNA provides a target for site-specific endonucleases. The rate of degradation of ompA mRNA parallels the rate of these endonucleolytic cleavages, implying that endonucleolytic rather than exonucleolytic attack is the initial step in ompA mRNA degradation. Thus the 5' noncoding region appears to be a determinant of mRNA stability, and endonucleolytic cleavages in the 5' noncoding region may well regulate expression of the ompA gene. 相似文献