全文获取类型
收费全文 | 5730篇 |
免费 | 480篇 |
国内免费 | 1篇 |
出版年
2023年 | 34篇 |
2022年 | 75篇 |
2021年 | 187篇 |
2020年 | 122篇 |
2019年 | 165篇 |
2018年 | 159篇 |
2017年 | 160篇 |
2016年 | 234篇 |
2015年 | 354篇 |
2014年 | 342篇 |
2013年 | 411篇 |
2012年 | 489篇 |
2011年 | 491篇 |
2010年 | 276篇 |
2009年 | 267篇 |
2008年 | 341篇 |
2007年 | 337篇 |
2006年 | 297篇 |
2005年 | 279篇 |
2004年 | 228篇 |
2003年 | 194篇 |
2002年 | 178篇 |
2001年 | 62篇 |
2000年 | 48篇 |
1999年 | 54篇 |
1998年 | 47篇 |
1997年 | 15篇 |
1996年 | 22篇 |
1995年 | 13篇 |
1994年 | 24篇 |
1993年 | 16篇 |
1992年 | 25篇 |
1991年 | 28篇 |
1990年 | 14篇 |
1989年 | 17篇 |
1988年 | 16篇 |
1987年 | 12篇 |
1986年 | 14篇 |
1985年 | 9篇 |
1984年 | 16篇 |
1983年 | 11篇 |
1982年 | 17篇 |
1981年 | 9篇 |
1979年 | 9篇 |
1977年 | 10篇 |
1975年 | 10篇 |
1974年 | 9篇 |
1971年 | 9篇 |
1970年 | 5篇 |
1968年 | 9篇 |
排序方式: 共有6211条查询结果,搜索用时 671 毫秒
21.
Isolation of molecular markers from specific chromosomal intervals using DNA pools from existing mapping populations.
下载免费PDF全文
![点击此处可从《Nucleic acids research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We present a general method for isolating molecular markers specific to any region of a chromosome using existing mapping populations. Two pools of DNA from individuals homozygous for opposing alleles for a targeted chromosomal interval, defined by two or more linked RFLP markers, are constructed from members of an existing mapping population. The DNA pools are then screened for polymorphism using random oligonucleotide primers and PCR (1). Polymorphic DNA bands should represent DNA sequences within or adjacent to the selected interval. We tested this method in tomato using two genomic intervals containing genes responsible for regulating pedicle abscission (jointless) and fruit ripening (non-ripening). DNA pools containing 7 to 14 F2 individuals for each interval were screened with 200 random primers. Three polymorphic markers were thus identified, two of which were subsequently shown to be tightly linked to the selected intervals. The third marker mapped to the same chromosome (11) but 45 cM away from the selected interval. A particularly attractive attribute of this method is that a single mapping population can be used to target any interval in the genome. Although this method has been demonstrated in tomato, it should be applicable to any sexually reproducing organism for which segregating populations are being used to construct genetic linkage maps. 相似文献
22.
Oxygen concentration regulates EGF-induced proliferation and EGF-receptor down regulation 总被引:2,自引:0,他引:2
D A Wing G D Talley T G Storch 《Biochemical and biophysical research communications》1988,153(3):952-958
Reducing oxygen from 20% to 2.5% increases EGF-induced DNA synthesis and cell proliferation in cultures of human diploid fibroblasts. Reducing oxygen also changes the pattern of EGF binding to the cell surface. The loss of surface binding that follows EGF attachment to cells in 20% oxygen does not occur in 2.5% oxygen. 相似文献
23.
E J Wing D M Magee A C Pearson A Waheed R K Shadduck 《Journal of immunology (Baltimore, Md. : 1950)》1986,137(9):2768-2773
The effect of M-CSF-exposed macrophages on murine splenic lymphocyte responses was determined. Resident peritoneal macrophages incubated with purified M-CSF for 48 hr inhibited lymphocyte proliferation to Con A, PHA, and listerial antigen as determined by [3H]TdR uptake, and inhibited Con A-stimulated lymphocyte IL 2 production. The inhibition was similar to that observed with macrophages from BCG-infected mice. Maximal suppression occurred at M-CSF concentrations of 500 U/ml or greater and when the incubation time with M-CSF was 48 hr or more. M-CSF effect was specific because rabbit anti-M-CSF IgG blocked the suppression whereas control rabbit IgG did not. Secretory products of macrophages could not be implicated in this interaction. Catalase and indomethacin, alone or together, did not reverse the inhibition. In addition, putative suppressive factors were not detected in supernatants of M-CSF-stimulated macrophages. Lymphocytes that were removed from macrophage monolayers and were recultured in medium plus Con A were able to proliferate. Macrophages stimulated by M-CSF therefore appear to have inhibitory activity for proliferating lymphocytes, and may play a role in immunoregulatory mechanisms. 相似文献
24.
Daniel Chappard Christian Alexandre Sabine Palle George Riffat 《Biotechnic & histochemistry》1986,61(2):93-96
Polyester fibers are not dissolved by either glycol methacrylate or methyl methacrylate. Commercial polyester wadding is consequently an advantageous material to use in getting precise orientation of tissue specimens during embedding in methacrylate. 相似文献
25.
Daniel Chappard Christian Alexandre Sabine Palle Georges Riffat 《Biotechnic & histochemistry》1986,61(3):145-149
A one-step clearing and embedding procedure for alizarin red S stained skeletons is described. Embryos are fixed in formalin, skinned and eviscerated. After staining in a 10 mg/liter solution of alizarin red S in 5% aqueous KOH, specimens are dehydrated in a graded series of acetone-polyester monomer solutions. Finally, the specimens are embedded at room temperature in the polyester resin. A special reusable metallic mold is described for embedment of large fetuses. Specimens previously cleared in glycerol can be processed with this method. 相似文献
26.
A one-step clearing and embedding procedure for alizarin red S stained skeletons is described. Embryos are fixed in formalin, skinned and eviscerated. After staining in a 10 mg/liter solution of alizarin red S in 5% aqueous KOH, specimens are dehydrated in a graded series of acetone-polyester monomer solutions. Finally, the specimens are embedded at room temperature in the polyester resin. A special reusable metallic mold is described for embedment of large fetuses. Specimens previously cleared in glycerol can be processed with this method. 相似文献
27.
The effect of sublethal inocula of Toxoplasma gondii on the course of listeriosis and salmonellosis in mice was investigated. Intravenous injection of T. gondii 24 hr after inoculation of Listeria monocytogenes increased mortality from 16% (L. monocytogenes alone) to 68% (L. monocytogenes + T. gondii) (P less than 0.001). Multiplication of L. monocytogenes in spleens also was increased significantly in mice given T. gondii. By 3 days after infection, mice that had received T. gondii and L. monocytogenes had approximately 10 times the number of L. monocytogenes per spleen compared to mice receiving L. monocytogenes alone. Similarly, mortality and the number of bacteria in spleens were increased in mice injected with Salmonella typhimurium and then inoculated with T. gondii. An in vitro assay of macrophage listeriacidal activity was used to investigate the mechanism of this decreased resistance. Peritoneal macrophages from mice injected with T. gondii were less bactericidal than macrophages from uninfected mice. Delayed hypersensitivity responses to L. monocytogenes antigen were markedly suppressed in mice injected with T. gondii. T. gondii infection appears to suppress both macrophage and T-lymphocyte function and may result in decreased resistance to infections caused by intracellular bacteria. 相似文献
28.
29.
A J Wing 《BMJ (Clinical research ed.)》1970,3(5725):753-755
30.