全文获取类型
收费全文 | 697篇 |
免费 | 144篇 |
国内免费 | 1篇 |
专业分类
842篇 |
出版年
2023年 | 6篇 |
2022年 | 9篇 |
2021年 | 19篇 |
2019年 | 8篇 |
2018年 | 7篇 |
2017年 | 8篇 |
2016年 | 10篇 |
2015年 | 22篇 |
2014年 | 25篇 |
2013年 | 24篇 |
2012年 | 38篇 |
2011年 | 37篇 |
2010年 | 29篇 |
2009年 | 24篇 |
2008年 | 37篇 |
2007年 | 38篇 |
2006年 | 32篇 |
2005年 | 34篇 |
2004年 | 38篇 |
2003年 | 17篇 |
2002年 | 27篇 |
2001年 | 19篇 |
2000年 | 17篇 |
1999年 | 20篇 |
1998年 | 11篇 |
1997年 | 10篇 |
1996年 | 20篇 |
1995年 | 7篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1992年 | 21篇 |
1991年 | 15篇 |
1990年 | 8篇 |
1989年 | 10篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1983年 | 11篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 14篇 |
1977年 | 10篇 |
1976年 | 7篇 |
1975年 | 12篇 |
1973年 | 8篇 |
1970年 | 6篇 |
1969年 | 5篇 |
1968年 | 7篇 |
排序方式: 共有842条查询结果,搜索用时 0 毫秒
1.
Multipoint mapping studies of six loci on chromosome 11 总被引:1,自引:0,他引:1
D A Meyers T H Beaty N E Maestri S D Kittur S E Antonarakis H H Kazazian 《Human heredity》1987,37(2):94-101
The six loci, beta-globin (HBBC), parathyroid hormone (PTH), oncogene c-Ha-ras-1 (HRAS1), insulin (INS), calcitonin (CAL) and catalase (CAT) loci, have been mapped to 11p in the order: CAT-CAL-PTH-HBBC-(HRAS1-INS). The purpose of the current study was to examine the linkage relationships, especially the multipoint relationships of these loci in detail. In the 18 families studied, a significant sex difference in recombination was found for the HBBC: HRAS1 linkage with more recombination in the male parent than the female parent (22 vs. 2%). The results of the multipoint analyses provided further evidence for the order CAT-CAL-PTH-HBBC-(HRAS1-INS); however, the order of the last two tightly linked loci is still not clear. 相似文献
2.
A device to measure fluorescein in tissue has been constructed from standard photographic equipment--an electronic strobe and a flashmeter both covered with interference filters. The instrument works well in the light and need not touch the area being measured, an advantage over existing fluorometers. The instrument has been used to measure the amount of dye in flaps in rats, pigs, and three humans. The results revealed that the amount of dye in a freshly made flap was rarely as much as in normal skin, and skin with less than 20 percent of the dye of control areas usually sloughed, although there were exceptions. In the future the instrument will be improved, and its readings will be compared to those obtained from radioactive microspheres, the present "gold standard" of techniques to measure vascularity. The instrument can be used to estimate the blood supply to any tissue and seems to be as reliable as the dermofluorometers already on the market. 相似文献
3.
4.
Aspects of the life cycle of marine nematodes 总被引:1,自引:0,他引:1
Summary 1. Life cycles of approximately one month are recorded for laboratory maintained cultures of chromadorid, monhysterid and oncholaimid nematodes.2. Amphimictic and parthenogenetic reproduction occurs in the species investigated. Reproduction inMonhystera parelegantula is by parthenogenesis.3. The chromadoridChromadorina epidemos and the oncholaimidViscosia macramphida are able to reproduce by either amphimixis or parthenogenesis.4.Acanthonchus cobbi, Chromadora macrolaimoides andEuchromadora gaulica are amphimitically reproducing species.
Aspekte des Lebenszyklus mariner Nematoden
Kurzfassung Bei einigen marinen Nematoden, die in Biscayne Bay (Florida) gesammelt und im Labor gezüchtet worden sind, vollzieht sich der gesamte Lebenszyklus ungefähr innerhalb eines Monats. BeiAcanthonchus cobbi, Chromadora macrolaimoides undEuchromadora gaulica ist zweigeschlechtliche Fortpflanzung festgestellt worden.Monohystera parelegantula vermehrt sich parthenogenetisch. Ein möglicherweise durch Umwelteinflüsse bedingter Wechsel von bisexueller und parthenogenetischer Fortpflanzung tritt beiChromadora epidemos undViscosia macramphida auf.相似文献
5.
One stallion and 54 mares were used in an experiment to evaluate the effect of postbreeding uterine lavage on pregnancy rate in mares. All mares were inseminated with 250 x 10(6) progressively motile sperm every other day during estrus until detection of ovulation. Mares (n = 18) were randomly assigned to one of three treatment groups: 1) no postbreeding uterine lavage (control); 2) uterine lavage at 0.5 h postbreeding; or 3) uterine lavage at 2 h postbreeding. A dilute solution of povidone-iodine (PIS; 0.05%) previously determined to render spermatozoa immotile in vitro was used to lavage the mare uteri. One liter PIS, prewarmed to 40 degrees C, was used for each lavage. Pregnancy status of mares was determined at 21 d and 36 d post ovulation, using transrectal ultrasonography. The pregnancy rate of Group 1 (66.7%) was higher than that of Group 2 (22.2%; P<0.05) or Group 3 (33.3%); P<0.10). The pregnancy rates of Groups 2 and 3 were similar (P>0.70). Evaluation of endometrial biopsies obtained from a separate set of mares (n = 3) on Day 6 post ovulation, both before and after uterine lavage, revealed no difference in the accumulation of inflammatory cells, suggesting adverse effects of lavage on fertility may have been due to excessive removal of spermatozoa from the uterus during the lavage process or damage to oviductal spermatozoa. 相似文献
6.
Purification and properties of a low-redox-potential tetraheme cytochrome c3 from Shewanella putrefaciens. 下载免费PDF全文
A I Tsapin K H Nealson T Meyers M A Cusanovich J Van Beuumen L D Crosby B A Feinberg C Zhang 《Journal of bacteriology》1996,178(21):6386-6388
Shewanella putrefaciens is a facultatively anaerobic bacterium in the gamma group of the proteobacteria, capable of utilizing a wide variety of anaerobic electron acceptors. An examination of its cytochrome content revealed the presence of a tetraheme, low-redox-potential (E'o = -233 mV), cytochrome c-type cytochrome with a molecular mass of 12,120 Da and a pI of 5.8. The electron spin resonance data indicate a bis-histidine coordination of heme groups. Reduction of ferric citrate was accompanied by oxidation of the cytochrome. The biochemical properties suggested that this protein was in the cytochrome c3 group, which is supported by N-terminal sequence data up to the first heme binding site. 相似文献
7.
FGFR2 exon IIIa and IIIc mutations in Crouzon, Jackson-Weiss, and Pfeiffer syndromes: evidence for missense changes, insertions, and a deletion due to alternative RNA splicing. 总被引:8,自引:0,他引:8 下载免费PDF全文
G. A. Meyers D. Day R. Goldberg D. L. Daentl K. A. Przylepa L. J. Abrams J. M. Graham Jr M. Feingold J. B. Moeschler E. Rawnsley A. F. Scott E. W. Jabs 《American journal of human genetics》1996,58(3):491-498
Fibroblast growth factor receptor 2 (FGFR2) mutations have been associated with the craniosynostotic conditions Crouzon, Jackson-Weiss, and Pfeiffer syndromes. Previously, mutations were described in the exons IIIa and IIIc, which form the extracellular, third immunoglobulin-like domain (IgIII) and adjacent linker regions, both of which are normally involved in ligand binding. For all three conditions, mutations were found in exon IIIc. Only in Crouzon syndrome were mutations identified in exon IIIa. In this study, 39 cases with one of these three conditions were screened for exon IIIa or IIIc mutations. Eleven mutations are reported in 17 unrelated cases. Mutations in exon IIIa are identified for not only Crouzon but also Jackson-Weiss and Pfeiffer syndromes. Four mutations in either exon IIIa or exon IIIc reported only in Crouzon syndrome are present also in one of the other two syndromes. Two insertions, one in exon IIIa in a Crouzon syndrome patient and the other in exon IIIc in a Pfeiffer syndrome patient, were observed. The latter mutation has the same alternative RNA splicing effect as a reported synonymous mutation for Crouzon syndrome. A missense mutation was detected in one Pfeiffer syndrome family in which two members had craniosynostosis without limb anomalies. The inter- and intrafamilial variability in expression of FGFR2 mutations suggests that these three syndromes, presumed to be clinically distinct, are instead representative of a spectrum of related craniosynostotic and digital disorders. 相似文献
8.
J Xu R C Levitt C I Panhuysen D S Postma E W Taylor P J Amelung K J Holroyd E R Bleecker D A Meyers 《American journal of human genetics》1995,57(2):425-430
Studies investigating the genetic control of total serum IgE levels are of major importance in understanding basic pathophysiologic mechanisms in atopy and asthma, since IgE levels predict onset and correlate with the clinical expression of these disorders. Previous analysis of data from 92 families, ascertained through a parent with asthma, showed evidence for recessive inheritance of high IgE levels with linkage to chromosome 5q. Since there was significant residual familial correlation in the one-locus segregation analysis, two-locus segregation and linkage analyses were performed. Segregation analyses provided evidence for a second major locus unlinked to the locus on 5q. Utilization of this two-locus model corroborates the previous evidence for linkage between this trait and markers on 5q31-q33. The LODs for the most informative marker D5S436 increased from 3.00 at 10% recombination to 4.67 at 9% recombination, when the two-locus model was used. Additional linkage studies are needed to map this second locus. These results demonstrate the importance of performing multilocus segregation and linkage analyses for quantitative traits that are related to the phenotype of a complex disorder. This approach has given further insight into the genetics of allergy and asthma by providing evidence for a two-locus model. 相似文献
9.
Normal chickens and chickens congenitally infected with an avian leukosis virus (ALV) of antigenic subgroup A were challenged with strains of Rous sarcoma virus (RSV) of two different antigenic subgroups (B and C) and tumor induction and growth as well as humoral antibody to viral envelope antigen (VEA) and tumor-specific surface antigen (TSSA) were measured. There was no effect of congenital ALV infection on RSV tumor incidence or latent period but the growth rate and size of the tumors were much higher in congenitally infected birds as compared to controls. Whereas most tumors in the RSV-challenged normal birds regressed, tumors in ALV-infected birds grew progressively. There were no striking differences in the number of birds in either group in the incidence of anti-TSSA or anti-VEA antibodies nor did the presence of either type of antibody reflect the tumor status of the host. 相似文献
10.
Effect of induced erythrocythemia on aerobic work capacity 总被引:5,自引:0,他引:5
Buick F. J.; Gledhill N.; Froese A. B.; Spriet L.; Meyers E. C. 《Journal of applied physiology》1980,48(4):636-642