全文获取类型
收费全文 | 95316篇 |
免费 | 476篇 |
国内免费 | 817篇 |
出版年
2022年 | 16篇 |
2021年 | 37篇 |
2020年 | 19篇 |
2019年 | 24篇 |
2018年 | 11864篇 |
2017年 | 10689篇 |
2016年 | 7496篇 |
2015年 | 694篇 |
2014年 | 393篇 |
2013年 | 419篇 |
2012年 | 4396篇 |
2011年 | 12941篇 |
2010年 | 12070篇 |
2009年 | 8291篇 |
2008年 | 9881篇 |
2007年 | 11456篇 |
2006年 | 372篇 |
2005年 | 589篇 |
2004年 | 1049篇 |
2003年 | 1096篇 |
2002年 | 835篇 |
2001年 | 326篇 |
2000年 | 217篇 |
1999年 | 96篇 |
1998年 | 35篇 |
1997年 | 43篇 |
1996年 | 21篇 |
1994年 | 25篇 |
1993年 | 44篇 |
1992年 | 54篇 |
1991年 | 75篇 |
1990年 | 38篇 |
1989年 | 27篇 |
1988年 | 38篇 |
1987年 | 33篇 |
1986年 | 26篇 |
1985年 | 26篇 |
1984年 | 20篇 |
1983年 | 36篇 |
1982年 | 21篇 |
1980年 | 17篇 |
1979年 | 20篇 |
1978年 | 18篇 |
1976年 | 17篇 |
1975年 | 20篇 |
1973年 | 15篇 |
1972年 | 259篇 |
1971年 | 278篇 |
1965年 | 14篇 |
1962年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 625 毫秒
201.
Three-dimensional structure of rotavirus 总被引:40,自引:0,他引:40
202.
Kazuhiro Nakaya 《Ichthyological Research》1988,34(4):431-442
Data on the individual variation and changes with growth in proportions and morphology are presented for the poorly known Apristurus longicephalus, and compared with those of other species. A. longicephalus is concluded to be a distinct species without synonyms, characterized by its long snout, widely separate nostrils, long caudal fin, short abdomen, very sparse teeth, and low number of monospondylous vertebrae. It is a species of small size, maturing at about 42 cm in total length. 相似文献
203.
Scale morphology, growth and the squarnation chronology are described for the hermaphroditic fish Rivulus marmoratus reared in the laboratory. The scales are round or oval shaped cycloid type, and their sizes are about 0.3–1.0 mm in diameter. The number of ridges increases more rapidly relative to the body growth of the fish in early stages, but this increase is proportionate to growth subsequently. Three loci of scale development have been identified. The scales first appeared on the center of the parietal region at 8 days after hatching. The second locus of scale formation was on the lateral line of the posterior end of the caudal peduncle. A third locus was later observed on the lower right corner of the operculum: The final squamation was completed at 6 weeks after hatching. 相似文献
204.
Conidia of the speciesFusarium culmorum /W.G.Sm./ Sacc. andFusarium graminearum Schwabe are characterized by variability in zearalenone production and dimensions depending on the substrate. The sporulation of isolates from some wheat eultivars have been deprived in vivo and in vitro in the first passage, but not their pathogenicity and toxic metabolites production. Nonsporulating strains produced lower quantités of zearalenone than sporulating ones. Liquid filtrates of such nonsporulating strains had a high phytotoxic effect on wheat caryopses. The crystalline toxin DAS /0,25 ug/ml/ had low phytotoxic effect on wheat caryopses. 相似文献
205.
Juliusz Perkowski Jerzy Chełkowski Ronald D. Plattner Piotr Goliński 《Mycotoxin Research》1991,7(2):115-120
Maize cobs withFusarium ear rot were collected at 1986 season and five infected byFusarium graminearum were analyzed for presence of triohothecenes and zearalenone. Collected material was subsampled forFusarium damaged kernels and corresponding axial stems and healthy looking kernels. All investigated cobs contained deoxynivalenol (DON) (range 18.0–131.5 mg/kg) and zearalenone (ZEA) (range 0.38–2.17 mg/kg), in four cobs 15-acetyl-deoxynivalenol (15-AcDON) (range 5.2–6.2 mg/kg) was present and two cobs besides three all metabolites contained 3-acetyl-deoxynivalenol (3-AcD0N) (range 0.5–0.8 mg/kg).The average of individual toxins amount in axial stems: in mg/kg was equal to: DON — 110.36, ZEA — 4.57, 15-AcD0N — 16.66, and 3-AcD0N — 1.32.Fusarium damaged kernels contained in average the following amount (mg/kg) of: DON 77.00, ZEA 0.98, 15-AcD0N 3.78 and 3-AcD0N 0.06. Healthy looking kernels contained DON 1.96 mg/kg and ZEA 0.07 mg/kg only. Cooccurrence of 3-AcDON and 15-AcDON in two samples was an interesting finding. The amount of DON in total cob was highly correlated (r = 0.94) with percentage ofFusarium damaged kernels in given ear. 相似文献
206.
207.
208.
209.
Phosphatidyl glycerolphosphate serves as glycerolphosphate donor in polymer synthesis 总被引:1,自引:0,他引:1
T H Chiu B Arnold S R Kim L L Yeh 《Biochemical and biophysical research communications》1985,128(2):906-912
Phosphatidyl glycerolphosphate was found to serve as the glycerolphosphate donor for polymer synthesis. When CDP-diglyceride and radiolabeled glycerolphosphate were incubated with the membrane enzyme prepared from Streptococcus sanguis, active syntheses of radiolabeled lipids and polymers were observed. The synthesis of polymer was not inhibited by low concentration of unlabeled phosphatidylglycerol. When [3H, 32P]glycerolphosphate was used, the polymer synthesized contained both 3H and 32P. The lipids formed were characterized as phosphatidylglycerol and phosphatidyl glycerolphosphate. The polymers formed from the latter were characterized as lipoteichoic acid like compounds by sodium dodecylsulfate-polyacrylamide gel electrophoresis. 相似文献
210.
Cytochrome P-450-catalyzed stereoselective epoxidation at the K region of benz[a]anthracene and benzo[a]pyrene 总被引:1,自引:0,他引:1
The enantiomers of K-region benz[a]anthracene (BA) 5,6-epoxide and benzo[a]pyrene (BP) 4,5-epoxide were resolved by chiral stationary-phase high-performance liquid chromatography (CSP-HPLC). The K-region epoxides formed in the metabolism of BA by liver microsomes from untreated (control), phenobarbital (PB)-treated, and 3-methylcholanthrene (MC)-treated male Sprague-Dawley rats were determined by CSP-HPLC to have a 5R,6S/5S,6R enantiomer ratio of 25:75, 21:79, and 4:96, respectively. The K-region 4,5-epoxide formed in the metabolism of BP by the same rat liver microsomal preparations contained a 4R,5S/4S,5R enantiomer ratio of 48:52 (control), 40:60 (PB), and 5:95 (MC), respectively. The results indicate that various cytochrome P-450 isozymes of rat liver exhibit different stereoselective properties in catalyzing the epoxidation reactions at the K region of BA and of BP. 相似文献