全文获取类型
收费全文 | 6010篇 |
免费 | 565篇 |
国内免费 | 2篇 |
出版年
2022年 | 39篇 |
2021年 | 117篇 |
2020年 | 63篇 |
2019年 | 67篇 |
2018年 | 78篇 |
2017年 | 60篇 |
2016年 | 134篇 |
2015年 | 266篇 |
2014年 | 262篇 |
2013年 | 388篇 |
2012年 | 484篇 |
2011年 | 441篇 |
2010年 | 258篇 |
2009年 | 210篇 |
2008年 | 372篇 |
2007年 | 384篇 |
2006年 | 322篇 |
2005年 | 275篇 |
2004年 | 280篇 |
2003年 | 275篇 |
2002年 | 276篇 |
2001年 | 68篇 |
2000年 | 42篇 |
1999年 | 57篇 |
1998年 | 86篇 |
1997年 | 53篇 |
1996年 | 50篇 |
1995年 | 40篇 |
1994年 | 54篇 |
1993年 | 43篇 |
1992年 | 35篇 |
1991年 | 31篇 |
1990年 | 43篇 |
1989年 | 34篇 |
1988年 | 33篇 |
1986年 | 29篇 |
1985年 | 38篇 |
1984年 | 37篇 |
1983年 | 40篇 |
1982年 | 41篇 |
1981年 | 41篇 |
1980年 | 33篇 |
1978年 | 27篇 |
1977年 | 25篇 |
1976年 | 33篇 |
1975年 | 29篇 |
1974年 | 28篇 |
1973年 | 27篇 |
1972年 | 24篇 |
1969年 | 25篇 |
排序方式: 共有6577条查询结果,搜索用时 265 毫秒
991.
Sheila T. Callender H. E. M. Kay Sylvia D. Lawler Rosemary E. Millard Ruth Sanger Patricia A. Tippett 《BMJ (Clinical research ed.)》1971,1(5741):131-133
At the onset of his disease a man with polycythaemia vera had chromosomally normal cells in the bone marrow and Rh blood group CDe/cDE. Five years later he developed pancytopenia with erythroid hyperplasia of the bone marrow. This was associated with the presence of a major abnormal clone, 45,XY,B-,C-,16+, a minor clone, 45,XY,2+,3-,C-, and a few apparently normal cells. At the same time Rh blood grouping showed two populations of red cells, one CDe/cDE and one giving the reactions of CDe/CDe which can be interpreted as CDe. If monosomic CDe be the correct interpretation the case provides a strong hint that the Rh complex locus is sited either on the long arm of a B-group chromosome or, less probably, on an autosome of the C group. 相似文献
992.
Hexosaminidase activity was determined in cultured and uncultured amniotic fluid cells taken from seven pregnant women who had previously given birth to infants with Tay-Sachs disease. Complete deficiency of hexosaminidase A was found in one case, indicating a Tay-Sachs fetus. The diagnosis was confirmed on examination of various tissues after therapeutic abortion. Of the other six cases three were considered heterozygous and three homozygous normal. These diagnoses were confirmed postnatally on examination of cord blood leucocytes, peripheral leucocytes, and urine. The activity of hexosaminidase A is appreciably decreased in dead cells and hence in uncultured amniotic fluid cells. Hence reliable identification in utero of the three genotypes may be achieved only by examining the cultured living amniotic cells. 相似文献
993.
994.
A black-pigmented strain developed spontaneously from a typical strain of Mycobacterium fortuitum. 相似文献
995.
996.
Ruth W. Dodge 《Applied microbiology》1973,25(6):935-939
A number of standard bacteriological media with supplements were tested for their ability to support in vitro growth of Ethiopian strains of Borrelia recurrentis. Propagation of 18 out of 21 strains occurred in Trypticase soy yeast broth to which bovine albumin (fraction V), N-acetyl glucosamine, and sodium pyruvate had been added. This medium supported a population of 10(7) organisms per ml and yielded a harvest of four to five times the original inoculum during the logarithmic phase of growth. Maximal yield varied from 1.4 x 10(7) to 3.4 x 10(7) organisms per ml. Generation time in optimal media was 11.3 h. Lesser multiplication of organisms occurred in other media tested. Strains from primary cultures were infective for the green monkey. Recovery of viable organisms from subculture has not been successful. 相似文献
997.
The metabolism of amino acids in the bovine lens. Their oxidation as a source of energy 总被引:1,自引:0,他引:1 下载免费PDF全文
1. The metabolism by the bovine lens of nine (14)C-labelled l-amino acids was studied. These were: alanine, aspartate, glutamate, leucine, lysine, proline, serine, tyrosine and tryptophan. 2. All were taken up by the tissue and incorporated into protein. 3. Aspartate and glutamate, although poorly taken up, were readily metabolized to CO(2). Radioactivity from glutamate was also found in glutathione, glutamine, proline and ophthalmic acid. Aspartate was converted into glutamate, glutathione, proline, alanine and lactate. 4. Alanine was largely converted into lactate, which was released into the medium, but incorporation of radioactivity into CO(2), glutamate, glutathione, aspartate and lipids also occurred. 5. Radioactivity from leucine was detected in CO(2), lipids, glutamate, glutathione, proline and glutamine. 6. Lysine was only slightly broken down by the bovine lens; radioactivity was observed in CO(2), glutamate, glutathione, proline and two unidentified compounds. 7. Proline was metabolized to glutamate from which CO(2), glutathione and glutamine were formed. Hydroxyproline in the capsule collagen was labelled. 8. Radioactivity from serine was found in CO(2), lipids, glutathione, glycine, cystine, ATP, lactate and three unidentified compounds, one of which was probably taurine. 9. Neither tyrosine nor tryptophan were metabolized by the bovine lens. 10. The ability of the lens to metabolize amino acids was also shown by measurement of NH(3) production: more NH(3) was formed when glucose was absent from the incubation medium. 11. These experiments suggest that oxidation of amino acids is a source of energy for the lens. 相似文献
998.
A recently described euglenoid of the genus Colacium inhabits the rectums of damselfly larvae during the winter as a nonflagellated, stalkless palmella stage. Contrary to previous reports, which were based on light microscope observations, ultrastructural observations establish that the reservoir and canal with its nonemergent flagella remain structurally intact in the palmella condition. The 2 non-emergent flagella are structurally distinct. The larger flagellum, which probably gives rise to the single, emergent flagellant of the swimming euglenoid, has the typical 9 + 2 microtubular arrangement, together with a paraflagellar rod throughout most of its length. The crystalline paraflagellar body, typical of swimming euglenoids, is absent. The smaller flagellum has a 9 + 0 arrangement of the axonemal microtubules. This flagellum appears to terminate within the reservoir with a successive loss of number and arrangement of microtubules near its distal end. Hair-like structures lining the reservoir membrane may represent preformed nontubular mastigonemes. The eyespot granules are clustered around the cytostome and do not display the compact organization or position typical of the flagellated stage or the stalked stage of Colacium. 相似文献
999.
James N. Miller Ruth A. Boak Charles M. Carpenter 《The Western journal of medicine》1958,88(4):297-299
A comparative study of the specificity of the Reiter protein complement fixation (RPCF) test and the Treponema pallidum immobilization (TPI) test on 180 sera showed that the results in 178 instances or 98.9 per cent were in agreement.The sensitivity of the RPCF test, when compared to the TPI test, on 189 sera from patients known to have syphilis was in agreement in 182 or 96.3 per cent, assuming a correlation exists between positive TPI and both the “reactive” or “weakly reactive” RPCF test results.As to reproducibility of results, the RPCF test results agreed in 84 of the 87 sera tested (95.4 per cent). The sera were tested at least three times on different days.Anticomplementary reactions were observed in three of 91 normal sera. 相似文献
1000.
Walther Hoffmann Ruth Peters 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1958,28(1):40-51
Ohne ZusammenfassungMit 7 AbbildungenHerrn Prof. Dr. R.v.Sengbusch zu seinem 60. Geburtstag gewidmet. 相似文献