全文获取类型
收费全文 | 109188篇 |
免费 | 7487篇 |
国内免费 | 16篇 |
专业分类
116691篇 |
出版年
2023年 | 574篇 |
2022年 | 463篇 |
2021年 | 1068篇 |
2020年 | 961篇 |
2019年 | 983篇 |
2018年 | 2627篇 |
2017年 | 2340篇 |
2016年 | 3284篇 |
2015年 | 4900篇 |
2014年 | 4979篇 |
2013年 | 6684篇 |
2012年 | 8133篇 |
2011年 | 7624篇 |
2010年 | 4889篇 |
2009年 | 3634篇 |
2008年 | 6245篇 |
2007年 | 6170篇 |
2006年 | 5614篇 |
2005年 | 5315篇 |
2004年 | 4984篇 |
2003年 | 4591篇 |
2002年 | 4201篇 |
2001年 | 2230篇 |
2000年 | 2198篇 |
1999年 | 1898篇 |
1998年 | 803篇 |
1997年 | 625篇 |
1996年 | 549篇 |
1995年 | 563篇 |
1994年 | 569篇 |
1993年 | 437篇 |
1992年 | 1260篇 |
1991年 | 1178篇 |
1990年 | 1056篇 |
1989年 | 989篇 |
1988年 | 933篇 |
1987年 | 791篇 |
1986年 | 735篇 |
1985年 | 798篇 |
1984年 | 699篇 |
1983年 | 574篇 |
1982年 | 445篇 |
1981年 | 433篇 |
1979年 | 599篇 |
1978年 | 471篇 |
1977年 | 412篇 |
1976年 | 387篇 |
1975年 | 442篇 |
1974年 | 469篇 |
1973年 | 474篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
181.
Cystic fibrosis typing with DNA probes and screening for ΔF508 deletion in families from Southern France 总被引:1,自引:1,他引:0
Mireille Claustres Marie Desgeorges Paule Kjellherg Hélène Bellet Jacques Demaille Michelle Ramsay 《Human genetics》1990,85(4):398-399
Summary A sample of 235 individuals from 49 French cystic fibrosis (CF) families with at least one living affected child was typed
with probes for restriction fragment length polymorphisms (RFLPs) known to be linked to the CF gene, and was screened for
the ΔF508 mutation. Using a combination of six probes, 44 out of the 49 families were sufficiently informative to enable prenatal
diagnosis or carrier determination. As in many other populations, linkage disequilibrium was found between the CF locus and
the haplotype B (XV2c: allele 1; KM19: allele 2), which accounts for about 78% of CF chromosomes in our families. The ΔF508
deletion was present in 64.3% of CF chromosomes. 相似文献
182.
Genoveva Keyeux Simone Gilgenkrantz Gérard Lefranc Marie-Paule Lefranc 《Human genetics》1990,85(6):617-622
Summary Two cases of chromosome 14 rearrangements with partial duplication which occurred de novo were analyzed by Southern blot analysis using IGH, D14S1 and PI probes. In the first case, with a 46,XX,14p+ karyotype, our study confirms that the additional material on chromosome 14p+ results from a duplication of the 14q region containing the IGH, D14S1 and PI loci. In the second case, our study reveals only one 14q32 locus per chromosome 14 indicating that the extra material does not contain the 14q32 region. Our results demonstrate that molecular probes of the 14q32 region are valuable tools for the characterisation of chromosome 14 abnormalities appearing de novo. 相似文献
183.
Herman J. Woerdenbag Wim van Uden Henderik W. Frijlink Coenraad F. Lerk Niesko Pras Theo M. Malingré 《Plant cell reports》1990,9(2):97-100
Summary Cell suspension cultures, derived from roots of Podophyllum hexandrum Royle (Berberidaceae), accumulate podophyllotoxin. In this study the use of -cyclodextrin in feeding the poorly water-soluble precursor coniferyl alcohol to these cultures is described. By complexation with -cyclodextrin, a solution of 3 mM coniferyl alcohol could be fed, resulting in enhanced podophyllotoxin accumulation. The same concentration of non-complexed suspended coniferyl alcohol had only little effect on the podophyllotoxin accumulation. -Cyclodextrin itself was proven to be non-toxic for the cells. It did not influence the podophyllotoxin content and it was not metabolized or used as a carbon source by the cells. For comparison, coniferin, the water-soluble -D-glucoside of coniferyl alcohol, was also fed in the same concentration. The effect of coniferin on the podophyllotoxin accumulation was stronger than that of coniferyl alcohol complexed with -cyclodextrin, but coniferin is not commercially available.Abbreviations -CD
-cyclodextrin
- NAA
naphthaleneacetic acid 相似文献
184.
Marie-Hélène Chaput Darasinh Sihachakr Georges Ducreux Dominique Marie Nasrine Barghi 《Plant cell reports》1990,9(8):411-414
In order to regenerate somatic hybrids, mesophyll protoplasts from a dihaploid potato, BF15 (H1), were electrofused with those from two other dihaploid clones, Aminca (H6) and Cardinal (H3). Determination of the ploidy level by flow cytometry showed that 10% of plants regenerated from the fusion experiment with BF15 + Aminca were diploids, 14% triploids, 63% tetraploids and very few were mixoploids or had a higher ploidy level. Using morphological markers and vigour in plant growth, we were able to recover a total of 24 somatic hybrid plants, respectively 20 and 4 hybrids (accounting for 12% and 13% of regenerants) from the fusions BF15 + Aminca and BF15 + Cardinal. Most of the somatic hybrids were at the expected tetraploid level (2n=4x=48). The hybrid nature was confirmed by examining isoenzyme patterns for malate dehydrogenase (MDH) and isocitrate dehydrogenase (ICD). 相似文献
185.
When used simultaneously, are laboratory and psychosocial methods of screening helpful to detect alcoholism in general practice? To examine this issue, systematic screening with a self-administered Michigan Alcoholism Screening Test and measurement of the plasma gamma-glutamyltransferase level was offered to 435 clients at a family medicine clinic. Whenever a positive finding was obtained the client was free to undergo a more detailed evaluation to confirm the diagnosis. A total of 200 subjects (126 women, 74 men) agreed to undergo screening. The results do not appear to lead to practical consequences among women, in whom no case was identified. In contrast, in the male population a rate of first detection of 9.5% (seven cases) should encourage such screening for alcoholism in family medicine. 相似文献
186.
L Montagnier D Berneman D Guétard A Blanchard S Chamaret V Rame J Van Rietschoten K Mabrouk E Bahraoui 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1990,311(12):425-430
Antibodies prepared against a peptide corresponding to the site of cyto-adherence of Mycoplasma genitalium adhesine inhibit or reduce the infectivity of the HIV-1BRU and HIV-2ROD strains of Human Immunodeficiency Virus in lymphoid cells. These results strengthen the hypothesis that some mycoplasmas may play an important part in HIV replication and pathogenicity. 相似文献
187.
Summary A new type of multistage fluidised-bed reactor was constructed to avoid the fluidisation irregularities by slow stirring of the bed. Aminoacylase immobilized on a polyacrylamide type bead polymer was used as biocatalyst for resolution of racemic amino acids. The efficiency was considerably higher than that of a traditional packed-bed reactor. 相似文献
188.
Control of M-phase by maturation-promoting factor 总被引:18,自引:0,他引:18
M Dorée 《Current opinion in cell biology》1990,2(2):269-273
189.
Effect of streptozotocin-diabetes on rat liver mitochondrial adenosine triphosphatase turnover. 总被引:1,自引:0,他引:1 下载免费PDF全文
The apparent turnover rates of some mitochondrial enzymes can be modified in diabetes. We studied the effect of streptozotocin-diabetes on the half-life of a protein tightly bound to the inner membrane, ATPase. The half-life (t 1/2), measured by the double-isotope technique, decreased by approx. 20% in diabetes (from approximately equal to 2.56 days in controls to approximately equal to 2.06 days in diabetic rats). These results suggest that diabetes produces an increase in degradation of ATPase by a mechanism which is not yet clear, possibly influenced by alterations induced by diabetes in hepatic lysosomes that are associated with hepatic autophagy. 相似文献
190.