全文获取类型
收费全文 | 18587篇 |
免费 | 1727篇 |
国内免费 | 17篇 |
专业分类
20331篇 |
出版年
2022年 | 134篇 |
2021年 | 249篇 |
2020年 | 138篇 |
2019年 | 194篇 |
2018年 | 243篇 |
2017年 | 189篇 |
2016年 | 363篇 |
2015年 | 585篇 |
2014年 | 663篇 |
2013年 | 888篇 |
2012年 | 1113篇 |
2011年 | 1147篇 |
2010年 | 765篇 |
2009年 | 725篇 |
2008年 | 980篇 |
2007年 | 1040篇 |
2006年 | 976篇 |
2005年 | 931篇 |
2004年 | 995篇 |
2003年 | 994篇 |
2002年 | 1013篇 |
2001年 | 301篇 |
2000年 | 239篇 |
1999年 | 267篇 |
1998年 | 283篇 |
1997年 | 199篇 |
1996年 | 177篇 |
1995年 | 176篇 |
1994年 | 157篇 |
1993年 | 200篇 |
1992年 | 182篇 |
1991年 | 181篇 |
1990年 | 184篇 |
1989年 | 152篇 |
1988年 | 159篇 |
1987年 | 164篇 |
1986年 | 137篇 |
1985年 | 173篇 |
1984年 | 151篇 |
1983年 | 163篇 |
1982年 | 168篇 |
1981年 | 176篇 |
1980年 | 142篇 |
1979年 | 123篇 |
1978年 | 127篇 |
1977年 | 127篇 |
1976年 | 118篇 |
1975年 | 106篇 |
1974年 | 128篇 |
1973年 | 117篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Donald E. Rivett Dean Hewish Alan Kirkpatrick Jerome Werkmeister 《Journal of Protein Chemistry》1999,18(3):291-295
Nine fatty acid–peptide hybrid molecules were constructed using the general formula CH3(CH2)
n
CO-Phe Asp Cys-amide and tested for their ability to inhibit cell lysis induced by the membrane-active peptide melittin. All of these molecules, where n = 4–14, inhibited the action of melittin to some extent, but the longer carbon chains were most effective. Several potential inhibitors were also constructed with conservative substitutions in the peptide portion of the molecule. All were effective to varying degrees. We concluded that in the hexapeptide inhibitor published by Blondelle et al. (1993), the role of the first three residues is only to provide hydrophobic interaction with the melittin and has no particular amino acid sequence specificity. Some of these inhibitors were found to inhibit the lytic activity of a melittin analogue which had only superficial sequence similarity to melittin and also a truncated form of melittin, indicating the generality of the action of the inhibitors.Deceased 5/4/98 相似文献
3.
Alan Emery 《American journal of human genetics》1985,37(4):832-833
4.
—A resolution of the enhancement of protein synthesis in the visual cortex of rats during first exposure to light (Richardson and Rose , 1972) was achieved by polyacrylamide gel electrophoresis using a double-labelling technique. Differential incorporation of lysine was established between exposed and control animals in two fractions of the soluble proteins and seven fractions of the insoluble proteins. This suggests that exposure to a new experience of this type involves a specific effect on protein synthesis, rather than a general stimulation across all fractions. 相似文献
5.
J H Richardson L L Steinmetz S B Deutscher W A Bookless W L Schmelzinger 《Analytical biochemistry》1979,97(1):17-23
A synchronously pumped krypton ion dye laser fluorescence system is shown to provide tunable, polarized, subnanosecond pulses at high repetition rates, modest peak powers, and low energy. Such a source is uniquely suited to fluorescence investigations of biochemical mechanisms. Applications of this fluorescence excitation source to analysis, life-time determination, and depolarization effects are discussed. 相似文献
6.
A double antibody radioimmunoassay technique is described for the measurement of anti-zona antibodies in the peripheral plasma of marmosets actively immunized against intact cow zonae pellucidae. The method has been shown to be a reliable, repeatable indicator of antibody titer, enabling direct comparison of the response obtained between marmosets. This is the first report of a procedure describing the active immunization of a primate against zona antigens, and the first time a radioimmunoassay technique has been used to monitor profiles of anti-cow zona antibody production following active immunization. The method should prove to be a useful tool in the evaluation of zona antigens as agents for immunocontraception. 相似文献
7.
8.
9.
Regulation of G(1) cell-cycle progression by oncogenes and tumor suppressor genes. 总被引:13,自引:0,他引:13
Progression of resting quiescent G(0) cells into early G(1) and transition across the restriction point are highly regulated processes. Mutation of proto-oncogenes and tumor suppressor genes regulating these transitions are targeted during oncogenesis. Recent work has underscored the importance of the G(0) to early G(1) transition and metabolism to neoplastic cells. 相似文献
10.
Marianne E. Walsh Charles M. Collins Thomas F. Jenkins Alan D. Hewitt Jeff Stark Karen Myers 《Soil & Sediment Contamination》2003,12(5):631-645
Fort Greely, Alaska has an extensive complex of weapon training and testing areas located on lands withdrawn from the public domain under the Military Lands Withdrawal Act (PL106-65). The Army has pledged to implement a program to identify possible munitions contamination. Because of the large size (344,165,000 m2) of the high hazard impact areas, characterization of these constituents will be difficult. We used an authoritative sampling design to find locations most likely to contain explosives-residues on three impact areas. We focused our sampling on surface soils and collected multi-increment and discrete samples at locations of known firing events and from areas on the range that had craters, pieces of munitions, targets, or a designation as a firing point. In the two impact areas used primarily by the Army, RDX was the most frequently detected explosive. In the impact area that was also used by the Air Force, TNT was the most frequently detected explosive. Where detected, the explosives concentrations generally were low (<0.05 mg/kg) except in soils near low-order detonations, where the explosive-filler was in contact with the soil surface. These low-order detonations potentially can serve as localized sources for groundwater contamination if positioned in recharge areas. 相似文献