全文获取类型
收费全文 | 766篇 |
免费 | 63篇 |
专业分类
829篇 |
出版年
2023年 | 5篇 |
2022年 | 6篇 |
2021年 | 21篇 |
2020年 | 12篇 |
2019年 | 9篇 |
2018年 | 18篇 |
2017年 | 9篇 |
2016年 | 17篇 |
2015年 | 32篇 |
2014年 | 29篇 |
2013年 | 25篇 |
2012年 | 39篇 |
2011年 | 43篇 |
2010年 | 19篇 |
2009年 | 22篇 |
2008年 | 32篇 |
2007年 | 37篇 |
2006年 | 32篇 |
2005年 | 24篇 |
2004年 | 27篇 |
2003年 | 26篇 |
2002年 | 20篇 |
2001年 | 19篇 |
2000年 | 17篇 |
1999年 | 16篇 |
1998年 | 12篇 |
1997年 | 8篇 |
1996年 | 6篇 |
1995年 | 8篇 |
1992年 | 12篇 |
1991年 | 7篇 |
1990年 | 18篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 12篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1975年 | 9篇 |
1974年 | 9篇 |
1973年 | 5篇 |
1969年 | 6篇 |
1968年 | 5篇 |
1966年 | 10篇 |
排序方式: 共有829条查询结果,搜索用时 15 毫秒
91.
92.
Y S Fan R L Eddy M G Byers L L Haley W M Henry N J Nowak T B Shows 《Cytogenetics and cell genetics》1989,52(1-2):83-84
The gene for the human mineralocorticoid receptor (MLR) was previously localized to chromosome 4. Here, we have localized this gene to 4q31.2 by in situ hybridization. This precise mapping of MLR will assist in the linkage analysis and genetic characterization of pseudohypoaldosteronism, an autosomal recessive disorder which likely results from a defect in the MLR gene. 相似文献
93.
This paper investigates marker-assisted introgression of a major gene into an outbred line, where identification of the introgressed gene is incomplete because marker alleles are not unique to the base populations (the same marker allele can occur in both donor and recipient population). Those markers are used to identify the introgressed allele as well as the background genotype. The effect of using those markers, as if they were completely informative on the retention of the introgressed allele, was examined over five generations of backcrossing by using a single marker or a marker bracket for different starting frequencies of the marker alleles. Results were calculated by using both a deterministic approach, where selection is only for the desired allele, and by a stochastic approach, where selection is also on background genotype. When marker allele frequencies in donor and recipient population diverged from 1 and 0 (using a diallelic marker), the ability to retain the desired allele rapidly declined. Marker brackets performed notably better than single markers. If selection on background marker genotype was applied, the desired allele could be lost even more quickly than expected at random because the chance that the allele, which is common in the donor line, is present on the locus identifying the introgressed allele and is surrounded by alleles common in the recipient line on the background marker loci, will descend from the donor line (double recombination has taken place), is a lot smaller than the chance that this allele will stem from the recipient line (in which the allele occurs in low frequency). Marker brackets again performed better. Preselection against marker homozygotes (producing uninformative gametes) gave a slightly better retention of the introgressed allele. 相似文献
94.
95.
96.
Data are presented on a polymorphism for erythrocyte glucose 6-phosphate dehydrogenase (G6PD) in a kangaroo species. Only one of the two alleles is expressed in any individual regardless of its sex. Population and breeding data are consistent with the hypothesis of X linkage of the locus, with the paternally derived X chromosome being inactive in erythroblasts of females. 相似文献
97.
GTPase from rod outer segments: characterization by photoaffinity labeling and tryptic peptide mapping 总被引:2,自引:0,他引:2
D J Takemoto B E Haley J Hansen O Pinkett L J Takemoto 《Biochemical and biophysical research communications》1981,102(1):341-347
The photoaffinity label [γ-32P]8-N3GTP has been used to identify GTP-binding components in highly purified preparations of GTPase from bovine rod outer segments. These preparations contain two major polypeptides of 37,000 and 39,000 daltons. In the presence of photolyzing radiation, [γ-32P]8-N3GTP is covalently attached to the 37,000 dalton polypeptide. Tryptic peptide mapping of this polypeptide indicates that it is highly related to the 39,000 dalton species that has been previously identified as a GTP-binding component. 相似文献
98.
The 45-kDa alpha subunit of the signal transducing Gs protein complex, which stimulates receptor-coupled adenylate cyclase, incorporated less of the photoaffinity probe, 8N3-[gamma-32P]GTP, in extracts from tumorigenic cell lines in comparison with nontumorigenic cell lines derived from mouse lung epithelium. Immunoblotting experiments using anti-Gs alpha antibodies demonstrated that tumor cells do not have a decreased amount of Gs alpha and photolabeling of tumor cell Gs alpha increased when the rate of nucleotide exchange was promoted. Therefore, tumor cell Gs alpha function may be altered. Consistent with this hypothesis is the observation that the tumor cells exhibited decreased responsiveness to the beta-adrenergic agonist, isoproterenol. Gs alpha photolabeling in growing nontumorigenic cells was reduced to a level resembling that observed in tumor cells, but photolabeling increased when cells became contact-inhibited. This increase in 8N3-[gamma-32P]GTP incorporation into Gs alpha by normal cells at confluence was not seen in the tumorigenic cells. Since Gs alpha photolabeling was inversely proportional to the percentage of [3H]thymidine-labeled nuclei at confluence, we suggest that the altered Gs alpha in tumor cells is involved in the loss of cell growth regulation. 相似文献
99.
A. L. Archibald S. Coupewhite C. S. Haley C. W. Beattie L. J. Alexander 《Animal genetics》1994,25(5):349-351
Restriction fragment length polymorphisms (RFLPs) were revealed at the porcine casein loci with the following combinations of restriction endonucleases and porcine cDNA clones: αs1,-casein (TaqI); αs2-casein (BamHI); and ß-casein (Sacl). These RFLPs were shown to be under simple monogenic control by segregation analysis of two- and three-generation families. The CASAS1, CASAS2 and CASB casein loci were also shown to be linked with no recombinant haplotypes observed amongst 77 meioses in Large White and Meishan F1 and F2 crosses. No recombinants were observed in a further 106 meioses that were informative for linkage between CASAS1 and CASAS2. 相似文献
100.
Horned beetles are emerging models in the study of coevolution between novel morphologies and behavior. In Onthophagus beetles, large males use horns to fight other males in brood tunnels while small males with higher mobility sneak around the large males to gain access to females. Mating tactics have rarely been described in other dung beetle genera. We studied the horned dung beetle Sulcophanaeus velutinus that exhibits two parallel horns on the prothorax and one on the head. We put two males of different horn lengths, but similar mass, in observation chambers and found that the large male with longer horns won access to the female in physical competition. Speed tests in artificial tunnels show that locomotion is impeded in large males, suggesting an advantage in mobility for males with small horns. This work contributes to the limited existing evidence on the function of alternative morphologies in horned dung beetles taxa. 相似文献