全文获取类型
收费全文 | 9073篇 |
免费 | 1198篇 |
国内免费 | 651篇 |
出版年
2024年 | 29篇 |
2023年 | 293篇 |
2022年 | 283篇 |
2021年 | 551篇 |
2020年 | 596篇 |
2019年 | 602篇 |
2018年 | 559篇 |
2017年 | 434篇 |
2016年 | 414篇 |
2015年 | 442篇 |
2014年 | 658篇 |
2013年 | 794篇 |
2012年 | 482篇 |
2011年 | 464篇 |
2010年 | 347篇 |
2009年 | 405篇 |
2008年 | 436篇 |
2007年 | 383篇 |
2006年 | 405篇 |
2005年 | 340篇 |
2004年 | 241篇 |
2003年 | 246篇 |
2002年 | 208篇 |
2001年 | 170篇 |
2000年 | 117篇 |
1999年 | 134篇 |
1998年 | 108篇 |
1997年 | 78篇 |
1996年 | 75篇 |
1995年 | 46篇 |
1994年 | 65篇 |
1993年 | 73篇 |
1992年 | 49篇 |
1991年 | 32篇 |
1990年 | 41篇 |
1989年 | 36篇 |
1988年 | 21篇 |
1987年 | 23篇 |
1986年 | 12篇 |
1985年 | 34篇 |
1984年 | 32篇 |
1983年 | 26篇 |
1982年 | 33篇 |
1981年 | 29篇 |
1980年 | 26篇 |
1979年 | 21篇 |
1978年 | 15篇 |
1977年 | 6篇 |
1973年 | 3篇 |
1950年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
Danny C. Wharton 《Zoo biology》1984,3(4):329-333
This article outlines some of the advantages inherent in domestic animal reproductive technology development and compares them to the disadvantages in such development in wildlife species. Species program planning (as proposed by the American Association of Zoological Parks and Aquariums' Species Survival Plan) is offered as an important first step in organizing appropriate research toward reproductive technology development in wildlife species. 相似文献
112.
113.
114.
Golgi complex beads are 10 nm particles arranged in rings on the smooth forming face of the Golgi complex that stain specifically with bismuth in arthropod cells. In vitro experiments with biological molecules spotted on to cellulose acetate strips indicated that bismuth bound to the beads through phosphate groups. We could detect a weak phosphorus signal from the beads using a new technique called electron spectroscopic imaging that is capable of very high spatial resolution (0.3–0.5 nm) and sensitivity (50 atoms of phosphorus). Detection was not obscured by tissue staining with bismuth or uranyl acetate or by using an inorganic buffer (Na cacodylate). Localization of phosphorus was greatly improved by using colour-enhanced computer pictures of the electron spectroscopic images and quantitating the images. The results indicate that the phosphorus content of the beads is large enough to account for their bismuth reactivity. 相似文献
115.
We have applied our recently developed technique of flash induced kinetic infrared spectroscopy to the rhodopsin/Meta I and rhodopsin/Meta II transitions. Features of the infrared spectrum reflecting the C=C-vibration and the isomeric form of the chromophore are in agreement with resonant Raman experiments. Different results are obtained for the C=N-vibration of the Schiff base retinal opsin link. They are interpreted in terms of a Schiff base protonated via an hydrogen bond. A proton transfer in the excited state is suggested to explain the deviating results. In addition we have obtained spectral changes which cannot be attributed to molecular changes in the chromophore. We assume that these spectral features reflect molecular events in the protein part of rhodopsin. 相似文献
116.
耐药菌,尤其是多重耐药菌的出现和持续进化给人类健康带来了巨大的威胁。在抗生素逐渐失去特效作用的情况下,科学界和医药界又把眼光重新投向了抗菌的天然生物-噬菌体,并在一些研究中证明了噬菌体可以作为新的武器去替代抗生素治疗耐药菌感染。通过对噬菌体治疗及衍生的裂解酶治疗的世界专利申请进行统计及分析,获得了专利发展趋势、申请人分布特点及主要专利申请人等信息,详细分析了噬菌体及裂解酶治疗的主要专利技术路线和研发热点。 相似文献
117.
118.
A vibrational study of the CD2 stretching bands of selectively deuterated palmitic and stearic acids
The C-D stretching regions of the infrared and Raman spectra of 14 different palmitic and stearic acids containing isolated CD2 groups are reported. Anomalous behaviour is observed when substitution occurs near the terminal methyl group, which behaviour can not be explained in terms of crystal field effects. 相似文献
119.
An unusual zwitterionic polar lipid component isolated from the halotolerant alga, Dunaliella parva Lerche, has been identified as 1(3),2-diacylglyceryl-3(1)-O-4′-(N,N,N-trimethyl) homoserine by means of infrared spectrometry, 1H- and 13C-NMR spectrometry and field desorption mass spectrometry of the intact lipid, as well as by its TLC mobilities and staining behaviour. Mass spectrometry of this lipid indicated the presence of the following major molecular species: 16:0–18:0 (24%); 18:3–18:3 (19%); 16:0–18:2 (16%); 16:0–18:1 (8%). 相似文献
120.