全文获取类型
收费全文 | 13883篇 |
免费 | 908篇 |
国内免费 | 7篇 |
出版年
2024年 | 23篇 |
2023年 | 55篇 |
2022年 | 175篇 |
2021年 | 274篇 |
2020年 | 161篇 |
2019年 | 242篇 |
2018年 | 350篇 |
2017年 | 300篇 |
2016年 | 496篇 |
2015年 | 720篇 |
2014年 | 866篇 |
2013年 | 930篇 |
2012年 | 1245篇 |
2011年 | 1183篇 |
2010年 | 760篇 |
2009年 | 588篇 |
2008年 | 890篇 |
2007年 | 779篇 |
2006年 | 706篇 |
2005年 | 654篇 |
2004年 | 637篇 |
2003年 | 514篇 |
2002年 | 415篇 |
2001年 | 372篇 |
2000年 | 340篇 |
1999年 | 234篇 |
1998年 | 97篇 |
1997年 | 83篇 |
1996年 | 58篇 |
1995年 | 53篇 |
1994年 | 43篇 |
1993年 | 37篇 |
1992年 | 86篇 |
1991年 | 60篇 |
1990年 | 45篇 |
1989年 | 51篇 |
1988年 | 28篇 |
1987年 | 32篇 |
1986年 | 22篇 |
1985年 | 25篇 |
1984年 | 13篇 |
1983年 | 16篇 |
1982年 | 14篇 |
1981年 | 12篇 |
1980年 | 13篇 |
1979年 | 10篇 |
1978年 | 17篇 |
1977年 | 8篇 |
1975年 | 13篇 |
1974年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
1.
2.
3.
4.
5.
In the present study, non‐thermal dielectric barrier discharge (DBD) plasma of induced structural changes of morin resulted in the isolation of one previously undescribed benzofuranone derivative, along with two known compounds. The chemical structures of these degradation products were elucidated by UV, NMR and FAB‐MS spectroscopic analyses. The isolated three compounds showed potent antioxidative activities in two different tests, with IC50 values in the range of 12.9–41.8 μm in the 2,2′‐azino‐bis (3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS+) radical scavenging activity, 19.0–71.9 μm for hydroxyl radical scavenging activity test. Furthermore, the new methoxylated benzofuranone exhibited enhancement of inhibitory effects against pancreatic lipase with an IC50 value of 90.7±1.6 μm , when compared to the parent morin. These results suggested that the degradation products isolated from plasma exposed morin might be beneficial for prevention of obesity and related diseases. 相似文献
6.
T Tobe S Minoshima S Yamase N H Choi M Tomita N Shimizu 《Cytogenetics and cell genetics》1991,57(4):193-195
SP-40,40 is a serum glycoprotein consisting of two different subunits (alpha and beta) assembled into a dimer by disulfide bonds. Northern blot hybridization, using total RNA from several cell lines, showed that SP-40,40 is expressed in glioblastoma and testicular tumor cells, as well as hepatoma cells. Spot blot hybridization of flow-sorted human chromosomes, using a SP-40,40 cDNA fragment as a probe, localized the gene for SP-40,40 to human chromosome 8. This gene has been given the designation CLI, for complement lysis inhibitor, by the Human Gene Nomenclature Committee. 相似文献
7.
8.
An NMR and nuclear Overhauser effect (NOE) analysis of Thermus thermophilus tRNAIle1a is presented. This species contains modifications including s2T54 and s4U8 [Horie, N., Hara-Yokoyama, M., Yokoyama, S., Watanabe, K., Kuchino, Y., Nishimura, S., & Miyazawa, T. (1985) Biochemistry 24, 5711-5715]. All the expected secondary and reverse Hoogsteen AU pairs were identified, with one possible exception. The general geometry of the T psi C loop is the same as the Escherichia coli species, and there is NOE evidence for an A9-UA12 triple. Preliminary measurements of solvent exchange rates of internally hydrogen-bonded bases suggest that this tRNA is more stable than previously studied E. coli and yeast tRNAs. 相似文献
9.
K. Choi M. D. Burow G. Church G. Burow A. H. Paterson C. E. Simpson J. L. Starr 《Journal of nematology》1999,31(3):283-290
Segregation of resistance to Meloidogyne arenaria in six BC₅F₂ peanut breeding populations was examined in greenhouse tests. Chi-square analysis indicated that segregation of resistance was consistent with resistance being conditioned by a single gene in three breeding populations (TP259-3, TP262-3, and TP271-2), whereas two resistance genes may be present in the breeding populations TP259-2, TP263-2, and TP268-3. Nematode development in clonally propagated lines of resistant individuals of TP262-3 and TP263-2 was compared to that of the susceptible cultivar Florunner. Juvenile nematodes readily penetrated roots of all peanut genotypes, but rate of development was slower (P = 0.05) in the resistant genotypes than in Florunner. Host cell necrosis indicative of a hypersensitive response was not consistently observed in resistant genotypes of either population. Three RFLP loci linked to resistance at distances of 4.2 to 11.0 centiMorgans were identified. Resistant and susceptible alleles for RFLP loci R2430E and R2545E were quite distinct and are useful for identifying individuals homozygous for resistance in segregating populations. 相似文献
10.