全文获取类型
收费全文 | 10446篇 |
免费 | 748篇 |
国内免费 | 5篇 |
出版年
2023年 | 63篇 |
2022年 | 132篇 |
2021年 | 268篇 |
2020年 | 180篇 |
2019年 | 180篇 |
2018年 | 244篇 |
2017年 | 203篇 |
2016年 | 374篇 |
2015年 | 510篇 |
2014年 | 573篇 |
2013年 | 743篇 |
2012年 | 834篇 |
2011年 | 869篇 |
2010年 | 530篇 |
2009年 | 472篇 |
2008年 | 603篇 |
2007年 | 626篇 |
2006年 | 591篇 |
2005年 | 497篇 |
2004年 | 432篇 |
2003年 | 354篇 |
2002年 | 380篇 |
2001年 | 116篇 |
2000年 | 86篇 |
1999年 | 90篇 |
1998年 | 100篇 |
1997年 | 42篇 |
1996年 | 61篇 |
1995年 | 61篇 |
1994年 | 58篇 |
1993年 | 57篇 |
1992年 | 55篇 |
1991年 | 45篇 |
1990年 | 41篇 |
1989年 | 48篇 |
1988年 | 38篇 |
1987年 | 47篇 |
1986年 | 32篇 |
1985年 | 48篇 |
1984年 | 37篇 |
1983年 | 52篇 |
1982年 | 36篇 |
1981年 | 41篇 |
1980年 | 25篇 |
1979年 | 29篇 |
1978年 | 26篇 |
1977年 | 38篇 |
1976年 | 23篇 |
1975年 | 18篇 |
1974年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 531 毫秒
71.
72.
The Genetic Extent of the Insertion Involved in the Flecked Translocation in the Mouse 总被引:4,自引:1,他引:3
下载免费PDF全文
![点击此处可从《Genetics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Eva M. Eicher 《Genetics》1967,55(2):203-212
73.
Eva Janovská 《Folia microbiologica》1964,9(4):256-258
Устойчивость каппа-фага (Serratia marcescens) и его мутанта «С» исследовалась в буферных растворах при pH от 2.5 до 12 с целью подтверждения, или опровержения, возможности их инактивирования в результате кратковременного доведения кислотности основной суспензии в течение приготовления концентрата фага до pH 4. Было установлено, что каппа-фаг и его с-мутант в среде с pH 4 и выше остаются относительно устойчивыми и что в этих пределах pH между обоими фагами нет существенных различий. Однако при низких pH (2,5–3,5) титр обоих фагов вскоре довольно резко падает, причем с-мутантинакмпбпруемся бысмрее, чем каппа-фаг. 相似文献
74.
The use of induced primuline fluorescence led to the discovery of a new type of yeast scars (multiple scars) in the generaKloeckera, Saccharomycodes, Nadsonia andHanseniaspora. The structure and ultrastructure of their surface was studied by electron microscopy, using carbon replicas and isolated cell walls. 相似文献
75.
Zusammenfassung Es werden verschiedene Typen von Einschlußkörperchen im Karyoplasma der Epithelzellen des menschlichen Nebenhodenepithels beschrieben. Die verschieden strukturierten Kerninklusionen werden als eine Differenzierungsreihe aufgefaßt. Sie beginnt mit kleinen rundlichen Körperchen aus feinfädigem Material und führt über die Ausbildung von Anhäufungen dichter homogener Kugeln zu großen Vakuolen wechselnden Inhaltes.
Herrn Professor Dr. W. Bargmann zum 60. Geburtstag gewidmet.
Mit Unterstützung durch die Deutsche Forschungsgemeinschaft. 相似文献
Summary Different types of inclusion bodies are described in the karyoplasm of the epithelial cells of the human epididymis. The structural differences between these inclusions are interpreted as being indicative of consecutive stages in the process of their formation. Thus small, spherical bodies consisting of a fine fibrous material are believed to be the initial stages in the formation of the inclusion bodies whereas the dense, homogenous globules are thought to represent a later stage. Large vacuoles containing different materials are regarded as the final stage in this process of differentiation.
Herrn Professor Dr. W. Bargmann zum 60. Geburtstag gewidmet.
Mit Unterstützung durch die Deutsche Forschungsgemeinschaft. 相似文献
76.
The work is concerned with the question of the effect of humic acids on the biological action of agropyrene, the effective substance from the rootstock of Agropyron repens (L.) P. BEAUV. The test organism was the alga Scenedesmus obliquus (TURP.) KRÜGER, cultivated in mineral solution. The basic biological test was the determination of the number and size of the cells of this alga. It was found that the way in which agropyrene acts on combined application with humus acids depends on which humus fraction is used. It can display a synergic action if humic acid is used, since this substance probably facilitates the penetration of agropyrene into the cells. On the other hand, fulvic acid counteracts the activity of agropyrene and this most probably by mutual binding and blocking of active groups and links. 相似文献
77.
F1 generace hybrid?Ph. vulgaris L. XPh. coccineus L. je v bílkovinných znacích zhruba intermedierní. V F2 generaci se objevuje ?těpení a r?zné stupně matro- ?i patroklinity. 相似文献
78.
The ultrastructure of the mature spermatozoa and spermatogenesis of the bivalve Scrobicularia plana are described. Support cells extend from the basal lamina to the lumen of the testis and are laterally connected to the germinal epithelium. Germ cells present intercellular bridges and flagella since the spermatogonial stage. While spermatogonia and spermatocytes appear connected to support cells by desmosome-like junctions, elongated spermatids are held at the acrosomal region by support cell finger-like processes. During spermiogenesis, the acrosomal vesicle differentiates from a golgian saccule and then migrates to the nuclear apex. A microtubular manchette arising from centrioles surrounds the acrosomal vesicle, the nucleus, and the mitochondria at the time these three organelles start their elongation, disappearing after that. The mature spermatozoon of S. plana lacks a distinct midpiece because the mitochondria extend from the region of the pericentriolar complex along the nucleus anteriorly for approximately 1.4 μm. The features of this bivalve type of modified spermatozoon are compared with those of other animal groups having similar modifications. 相似文献
79.
80.
City spore concentrations in the European Economic Community (EEC). VI. Poaceae (Grasses), 1982–1986
Frits Th. M. Spieksma Gennaro D'amato John Mullins Nicole Nolard Reinhard Wachter Eva R. Weeke 《Aerobiologia》1989,5(1):38-43
Summary Airborne grass-pollen concentrations in six cities in the EEC are compared, based on observations from five years, 1982–1986.
Results show that there are quantitative differences both between the monitoring stations and between the years. Very provisionally,
the average seasonal total of the European urban airborne grass-pollen concentration can be put at 4 to 5000 per m3 of air. Also qualitatively, regarding the seasonal fluctuations, there are differences between the stations, and between
the years. Generally, the results confirm that June is the most typical grass-pollen month in northwestern Europe, whereas
in mediterranean Europe May is the more prominent grass-pollen period. There seems to be little coherence between the starting
dates of the grass-pollen season even at relatively nearby stations in northwestern Europe, suggestive for a great influence
of the actual weather situation. 相似文献