全文获取类型
收费全文 | 782篇 |
免费 | 46篇 |
出版年
2021年 | 5篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 7篇 |
2016年 | 10篇 |
2015年 | 14篇 |
2014年 | 23篇 |
2013年 | 34篇 |
2012年 | 36篇 |
2011年 | 38篇 |
2010年 | 19篇 |
2009年 | 23篇 |
2008年 | 26篇 |
2007年 | 37篇 |
2006年 | 48篇 |
2005年 | 39篇 |
2004年 | 34篇 |
2003年 | 41篇 |
2002年 | 45篇 |
2001年 | 14篇 |
2000年 | 15篇 |
1999年 | 18篇 |
1998年 | 15篇 |
1997年 | 15篇 |
1996年 | 10篇 |
1995年 | 14篇 |
1994年 | 11篇 |
1993年 | 15篇 |
1992年 | 13篇 |
1991年 | 9篇 |
1990年 | 13篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1985年 | 9篇 |
1984年 | 12篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 9篇 |
1980年 | 5篇 |
1976年 | 4篇 |
1974年 | 6篇 |
1972年 | 11篇 |
1971年 | 4篇 |
1969年 | 5篇 |
1968年 | 7篇 |
1967年 | 4篇 |
1932年 | 5篇 |
1930年 | 4篇 |
1927年 | 6篇 |
排序方式: 共有828条查询结果,搜索用时 15 毫秒
41.
42.
43.
Patrik Andersson Bernard Gsell Beat Wipf Hans Senn Gottfried Otting 《Journal of biomolecular NMR》1998,11(3):279-288
An HMQC experiment is proposed, dubbed FHMQC, where water flip-back is achieved by a single water-selective pulse preceding the basic HMQC pulse sequence. The scheme is demonstrated with a 15N, 1H-HMQC spectrum of uniformly 15N/2H-labelled S. aureus DNA gyrase B with a molecular weight of 45 kDa for the unlabelled protein. The sensitivity of the experiment is improved compared to that of an FHSQC spectrum. It is further shown that the original FHSQC experiment can be shortened by the use of bipolar gradients. Relaxation times of different 15N magnetizations and coherences were measured. The new FHMQC scheme is implemented in 3D NOESY-15N-HMQC and 3D15 N-HMQC-NOESY-15N-HMQC pulse sequences which are demonstrated with a 24 kDa fragment of uniformly 15N/13C/2H-labelled S. aureus DNA gyrase B. 相似文献
44.
Patrik Andersson Kerstin Nordstrand Maria Sunnerhagen Edvards Liepinsh Ivars Turovskis Gottfried Otting 《Journal of biomolecular NMR》1998,11(4):445-450
Spin-state selective experiments, HSQC-/ and CT-HMQC-/, are proposed for the simple and rapid measurement of scalar one-bond coupling constants in two-dimensional,1 H-detected 15N-1H or13 C-1H correlation experiments based on HSQC and HMQC schemes. Pairs of subspectra are obtained, containing either the high-field or the low-field component of the doublet representing the one-bond coupling constant. The subspectral editing procedure retains the full sensitivity of HSQC and HMQC spectra recorded without heteronuclear decoupling during data acquisition, with a spectral resolution similar to that of decoupled spectra. 相似文献
45.
L E Gundersen R B Dunlap N G Harding J H Freisheim F Otting F M Huennekens 《Biochemistry》1972,11(6):1018-1023
46.
47.
Summary Metabolism of the polycyclic hydrocarbon benzo(a)pyrene(BP) to watersoluble products was measured in cultured human leukocytes from 35 healthy volunteers. The classification into 3 different groups with respect to degree of BP metabolism fits that obtained in a previous population and family study, where only the ratio of aryl hydrocarbon hydroxylase (AHH) activity of 3-methylcholanthrene (3MC) treated cultures to the activity of control cultures was measured. These data support previous observations that metabolism of polycyclic hydrocarbons is under genetic control.
This work was supported in part by NIH Research Grant GM 15597 and Grant Ke 217/1 Deutsche Forschungsgemeinschaft (DFG). 相似文献
Zusammenfassung In der vorliegenden Arbeit wurde der Metabolismus des carcinogenen Kohlen wasserstoffes Benzpyren zu wasserlöslichen Produkten in Leukocytenkulturen von 35 gesunden Individuen untersucht. Hinsichtlich der Geschwindigkeit im Benzpyrenmetabolismus können 3 Gruppen unterschieden werden. Diese Einteilung ist in völliger Übereinstimmung mit der einer Populations-und Familienstudie, wo das Verhältnis der Aryl-Hydrocarbon-Hydroxylase-Aktivität von 3-Methylcholanthren-behandelten Leukocytenkulturen zu der von Kontrollkulturen bestimmt wurde. Diese Ergebnisse stützen die Beobachtung, daß der Metabolismus von carcinogenen Kohlenwasserstoffen unter genetischer Kontrolle ist.
This work was supported in part by NIH Research Grant GM 15597 and Grant Ke 217/1 Deutsche Forschungsgemeinschaft (DFG). 相似文献
48.
Genome‐wide SNP analysis unveils genetic structure and phylogeographic history of snow sheep (Ovis nivicola) populations inhabiting the Verkhoyansk Mountains and Momsky Ridge (northeastern Siberia) 下载免费PDF全文
Arsen V. Dotsev Tatiana E. Deniskova Innokentiy M. Okhlopkov Gabor Mészáros Johann Sölkner Henry Reyer Klaus Wimmers Gottfried Brem Natalia A. Zinovieva 《Ecology and evolution》2018,8(16):8000-8010
Insights into the genetic characteristics of a species provide important information for wildlife conservation programs. Here, we used the OvineSNP50 BeadChip developed for domestic sheep to examine population structure and evaluate genetic diversity of snow sheep (Ovis nivicola) inhabiting Verkhoyansk Range and Momsky Ridge. A total of 1,121 polymorphic SNPs were used to test 80 specimens representing five populations, including four populations of the Verkhoyansk Mountain chain: Kharaulakh Ridge–Tiksi Bay (TIK, n = 22), Orulgan Ridge (ORU, n = 22), the central part of Verkhoyansk Range (VER, n = 15), Suntar‐Khayata Ridge (SKH, n = 13), and Momsky Ridge (MOM, n = 8). We showed that the studied populations were genetically structured according to a geographic pattern. Pairwise FST values ranged from 0.044 to 0.205. Admixture analysis identified K = 2 as the most likely number of ancestral populations. A Neighbor‐Net tree showed that TIK was an isolated group related to the main network through ORU. TreeMix analysis revealed that TIK and MOM originated from two different ancestral populations and detected gene flow from MOM to ORU. This was supported by the f3 statistic, which showed that ORU is an admixed population with TIK and MOM/SKH heritage. Genetic diversity in the studied groups was increasing southward. Minimum values of observed (Ho) and expected (He) heterozygosity and allelic richness (Ar) were observed in the most northern population—TIK, and maximum values were observed in the most southern population—SKH. Thus, our results revealed clear genetic structure in the studied populations of snow sheep and showed that TIK has a different origin from MOM, SKH, and VER even though they are conventionally considered a single subspecies known as Yakut snow sheep (Ovis nivicola lydekkeri). Most likely, TIK was an isolated group during the Late Pleistocene glaciations of Verkhoyansk Range. 相似文献
49.
50.