全文获取类型
收费全文 | 234451篇 |
免费 | 14333篇 |
国内免费 | 122篇 |
出版年
2018年 | 7716篇 |
2017年 | 7592篇 |
2016年 | 6146篇 |
2015年 | 2371篇 |
2014年 | 2960篇 |
2013年 | 4214篇 |
2012年 | 6977篇 |
2011年 | 12067篇 |
2010年 | 9227篇 |
2009年 | 8766篇 |
2008年 | 10382篇 |
2007年 | 12170篇 |
2006年 | 4898篇 |
2005年 | 5465篇 |
2004年 | 5308篇 |
2003年 | 5508篇 |
2002年 | 5423篇 |
2001年 | 8503篇 |
2000年 | 8769篇 |
1999年 | 6311篇 |
1998年 | 1993篇 |
1997年 | 2050篇 |
1996年 | 1819篇 |
1993年 | 1701篇 |
1992年 | 5208篇 |
1991年 | 5386篇 |
1990年 | 5142篇 |
1989年 | 5132篇 |
1988年 | 4733篇 |
1987年 | 4493篇 |
1986年 | 4076篇 |
1985年 | 4234篇 |
1984年 | 3420篇 |
1983年 | 2928篇 |
1982年 | 1942篇 |
1981年 | 1728篇 |
1980年 | 1718篇 |
1979年 | 3211篇 |
1978年 | 2545篇 |
1977年 | 2278篇 |
1976年 | 2081篇 |
1975年 | 2556篇 |
1974年 | 2884篇 |
1973年 | 2802篇 |
1972年 | 3238篇 |
1971年 | 2911篇 |
1970年 | 2122篇 |
1969年 | 2022篇 |
1968年 | 1906篇 |
1967年 | 1740篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
In vitro incubation of thymocytes with [2-14C]acetate results in a more intensive label incorporation into chromatin lipids as compared to nuclear lipids. The deleterious effect of gamma-irradiation leads to specific changes in [2-14C]acetate incorporation into the total fraction of phosphatidylcholine-phosphatidylserine and chromatin sphingomyelin. This is paralleled with an increase in the ratio of specific radioactivities of chromatin cardiolipin and nuclear cardiolipin. The changes in specific radioactivities of sphingomyelin, phosphatidylcholine-phosphatidylserine and cardiolipin suggest a role of phospholipids in the mechanisms of regulating the activity of intranuclear structures. 相似文献
993.
S A Bitko L O Dynga A R Shikhman Z F Shmakova N I Briko 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1990,(4):3-7
The amino acid composition of cell walls and surface proteins, isolated from virulent (M+) and avirulent (M-) streptococcal strains (group A, type 29) has been determined by the method of E. H. Beachey et al. The kinetics of the lysis and proteolysis of streptococcal cell walls with muramidase and protease obtained from Actinomyces levoris and streptolysin has been studied. The constants describing the progress rates of these processes has been determined; their values in case of both lysis and proteolysis are higher in virulent strains than in avirulent ones. 相似文献
994.
995.
F Rabanal I Haro F Reig J M García-Antón 《International journal of peptide and protein research》1990,36(1):26-30
The synthesis of three hepatitis B surface antigens derived from S and pre-S proteins (adw S(140-147), [Tyr148] adw S(139-148), and adw pre-S(120-145)) has been accomplished by the continuous flow Fmoc-polyamide solid phase method. The use of different scavengers and trimethylsilyl bromide (TMSBr) in trifluoroacetic acid as deprotecting procedures is discussed. 相似文献
996.
997.
998.
Journal of Ichthyology - The paper considers the effect of the Sea of Azov salinization on the food supply to anchovy Engraulis encrasicolus maeoticus as the level of salinity was rising from 12.7... 相似文献
999.
Relationships between the strongyloid nematodesRugopharynx delta, R. zeta, R. omega, R. longibursaris, R. mawsonae andR. sigma, all from macropodid marsupials, were investigated using allozyme data. The phylogenetic trees derived from the electrophoretic data set were congruent with those of the hosts and were consistent with the hypothesis that the species complex originated in pademelons of the genusThylogale and diversified in rock-wallabies (Petrogale spp.) and scrub wallabies of the subgenusNotamacropus. Host switching is evident only between closely related macropodid taxa. 相似文献
1000.