全文获取类型
收费全文 | 8087篇 |
免费 | 478篇 |
国内免费 | 2篇 |
出版年
2023年 | 22篇 |
2022年 | 40篇 |
2021年 | 181篇 |
2020年 | 88篇 |
2019年 | 123篇 |
2018年 | 179篇 |
2017年 | 141篇 |
2016年 | 234篇 |
2015年 | 319篇 |
2014年 | 387篇 |
2013年 | 509篇 |
2012年 | 625篇 |
2011年 | 723篇 |
2010年 | 405篇 |
2009年 | 340篇 |
2008年 | 438篇 |
2007年 | 512篇 |
2006年 | 438篇 |
2005年 | 391篇 |
2004年 | 366篇 |
2003年 | 367篇 |
2002年 | 379篇 |
2001年 | 141篇 |
2000年 | 94篇 |
1999年 | 73篇 |
1998年 | 65篇 |
1997年 | 51篇 |
1996年 | 38篇 |
1995年 | 36篇 |
1994年 | 27篇 |
1993年 | 25篇 |
1992年 | 42篇 |
1991年 | 46篇 |
1990年 | 36篇 |
1989年 | 40篇 |
1988年 | 36篇 |
1987年 | 37篇 |
1986年 | 33篇 |
1985年 | 36篇 |
1984年 | 38篇 |
1983年 | 29篇 |
1977年 | 31篇 |
1976年 | 29篇 |
1975年 | 34篇 |
1974年 | 25篇 |
1973年 | 29篇 |
1972年 | 29篇 |
1971年 | 21篇 |
1968年 | 31篇 |
1966年 | 21篇 |
排序方式: 共有8567条查询结果,搜索用时 203 毫秒
1.
Using two-dimensional thin-layer chromatography, the effect of serotonin on the yield of thymine dimers and on cleavage of the N-glycosidic bond in the DNA irradiated with ultraviolet (UV) light and X-ray was studied. Bound serotonin was shown to reduce the synthesis of UV-induced thymine dimers but had no effect on the number of X-ray-induced breaks in the N-glycoside bonds in thymidine residues. The data obtained are discussed in terms of the mechanisms of serotonin involvement in the photoprotection of yeast cells from the lethal action of UV and X-ray irradiations. 相似文献
2.
The activity of cAMP-dependent protein kinases, cAMP binding and the spectrum of cAMP-binding proteins in renal papillary cytosol of intact rats and of rats kept on a water-deprived diet for 24 hours were investigated. It was found that the stimulation of protein kinases by 10(-6) M cAMP in the experimental group was significantly higher than in the control one. On DEAE-cellulose chromatography, the position of peaks of the specific cAMP binding corresponded to those of the regulatory cAMP-dependent protein kinases type I and II. Under these conditions, more than 80% of the binding activity in intact animals was localized in peak II, whereas in rats kept on a water-deprived diet over 60% of the binding activity was localized in peak I. The total binding activity of cytosol in experimental animals remained unchanged is compared to intact rats. It is suggested that in renal papilla dehydration is accompanied by the induction of synthesis of regulatory subunits of cAMP-dependent protein kinase type I. 相似文献
3.
Glushakova A. M. Lysak L. V. Kachalkin A. V. Ivanova A. E. Umarova A. B. Abramyan I. A. Ezhelev Z. S. Maksimova I. A. 《Microbiology》2021,90(2):176-186
Microbiology - In a model experiment, the transformation of microbial complexes of cultivated saprotrophic bacteria and yeasts during freezing-thawing was studied in various natural substrates that... 相似文献
4.
5.
Olga Maslova Oleg Fedevych Nadiia Shuvalova Olena Deryabina Volodymyr Zhovnir Miroslav Novak Peter Kruzliak 《Cell and tissue banking》2016,17(2):335-339
The need for selection of the optimal material for the manufacturing of cardio-patches can be resolved by the use of cryostored autologous pericardial tissue. This short communication is a concise fragment of a large-scale research and demonstrates only the efficiency of cell culturing before and after pericardial preservation in the low temperature conditions. 相似文献
6.
Household‐level correlates of children's physical activity levels in and across 12 countries 下载免费PDF全文
Deirdre M. Harrington Fiona Gillison Stephanie T. Broyles Jean‐Philippe Chaput Mikael Fogelholm Gang Hu Rebecca Kuriyan Anura Kurpad Allana G. LeBlanc Carol Maher Jose Maia Victor Matsudo Timothy Olds Vincent Onywera Olga L. Sarmiento Martyn Standage Mark S. Tremblay Catrine Tudor‐Locke Pei Zhao Peter T. Katzmarzyk for the ISCOLE Research Group 《Obesity (Silver Spring, Md.)》2016,24(10):2150-2157
7.
8.
E A Ivanova 《Ontogenez》1987,18(3):320-323
The influence of testosterone on the rate of total protein synthesis in the reproductive tract tissues and muscles was studied in the guinea pig male embryos from 26 days of development until birth. The rate of protein synthesis was estimated by the intensity of 3H-leucine incorporation per 1 mg protein for 30 min. Testosterone increased the rate of protein synthesis at all studies stages. A higher rate of protein synthesis was revealed at the stages of active morphogenesis and growth of rudiments and organs of genital system and correlated with their ability of 3H-testosterone uptake (Ivanova, 1982). 相似文献
9.
R Kh Iafaev V V Dudareva T G Ivanova E B Kaganer L V Loseva 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1986,(11):16-20
The short-term prognosis of the epidemic situation requires the establishment of the system of constant surveillance, which takes into account the data on morbidity rates for several years, both total and in various age groups, the data on the morbidity level and its changes, induced by meningococci of the epidemic group, in the IV quarter of the year, the data on the level of carriership among the indicator groups of the population in this period, as well as the data on changes in antibody titers in the sera of donor blood samples taken in summer and in December. 相似文献
10.
A systematic study of transformation reactions of Actinomycetes with respect to the progesterone molecule was undertaken. The results obtained, i.e. the types of transformation reactions in different actinomycete species, were evaluated from the point of view of taxonomy. The actinomycetes tested were divided according to the transformation types into three groups: (1) a group of species transforming progesterone in the 16α-position; (2) a group of species transforming progesterone in the β-position; (3) a group of species in which no capacity to transform progesterone into another steroid derivative was established. From the point of view of Actinomycete classification the transformation reactions on the steroid molecule fulfil all the requirements of taxonomic features of Actinomycetes. They appear to be specific properties, independent of strictly cultivation conditions and common to all the strains of individual actinomycete species tested. 相似文献