全文获取类型
收费全文 | 995430篇 |
免费 | 110249篇 |
国内免费 | 687篇 |
专业分类
1106366篇 |
出版年
2018年 | 9127篇 |
2017年 | 8537篇 |
2016年 | 12324篇 |
2015年 | 16804篇 |
2014年 | 19819篇 |
2013年 | 28035篇 |
2012年 | 31463篇 |
2011年 | 31948篇 |
2010年 | 21656篇 |
2009年 | 19899篇 |
2008年 | 28332篇 |
2007年 | 28991篇 |
2006年 | 27575篇 |
2005年 | 26519篇 |
2004年 | 26315篇 |
2003年 | 25348篇 |
2002年 | 24524篇 |
2001年 | 47392篇 |
2000年 | 47773篇 |
1999年 | 37805篇 |
1998年 | 13063篇 |
1997年 | 13608篇 |
1996年 | 12771篇 |
1995年 | 11969篇 |
1994年 | 11658篇 |
1993年 | 11560篇 |
1992年 | 30694篇 |
1991年 | 30034篇 |
1990年 | 29279篇 |
1989年 | 28516篇 |
1988年 | 26579篇 |
1987年 | 24837篇 |
1986年 | 23026篇 |
1985年 | 22909篇 |
1984年 | 18803篇 |
1983年 | 15949篇 |
1982年 | 11994篇 |
1981年 | 10694篇 |
1980年 | 10111篇 |
1979年 | 17161篇 |
1978年 | 13385篇 |
1977年 | 12138篇 |
1976年 | 10963篇 |
1975年 | 12270篇 |
1974年 | 13081篇 |
1973年 | 12954篇 |
1972年 | 11555篇 |
1971年 | 10608篇 |
1970年 | 9141篇 |
1969年 | 8832篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Human long-latency auditory evoked potentials were studied during simulation with variable-amplitude pulse sequences from a sound source moving to and from the subject. The N1 peak parameters were shown to depend on an accurate estimate of the direction of the change in the distance to the sound source. Differences in the processing of signals that simulated the approaching and/or distancing of the sound source were found in the N1 and P2 component parameters of on- and off-responses as was a more pronounced long negative potential shift in the evoked response to the approaching source as compared to the distancing source. 相似文献
992.
Yeast cell mortality related to a high-pressure shift: occurrence of cell membrane permeabilization 总被引:3,自引:0,他引:3
The shrinkage of yeast cells caused by high-pressure treatment (250 MPa, 15 min) was investigated using direct microscopic observation. A viable staining method after treatment allowed the volume variation of two populations to be distinguished: an irreversible volume decrease (about 35% of the initial volume) of pressure-inactivated cells during pressure holding time, and viable cells, which were less affected. A mass transfer was then induced during high-pressure treatment. Causes of this transfer seem to be related to a pressure-induced membrane permeabilization, allowing a subsequent leakage of internal solutes, where three ions (Na+, K+ and Ca2+), plus endogenous glycerol, were verified. This glycerol leakage was found to occur after yeast pressurization in a medium having low water activity, although the yeast was not inactivated. All these observations lead to the hypothesis that pressure-induced cell permeabilization could be the cause of yeast inactivation under pressure. 相似文献
993.
J. Dierschke T. Krüger F. Hüttmann F. Bairlein Kerstin Müller G. Scheiffarth H. -W. Helb W. Irsch W. Lantermann B. Haubitz W. Winkel und J. Haffer 《Journal of Ornithology》2003,144(4):484-498
Ohne Zusammenfassung 相似文献
994.
Simon D X Chuong Robert T Mullen Douglas G Muench 《The Journal of biological chemistry》2002,277(4):2419-2429
The control of subcellular mRNA localization and translation is often mediated by protein factors that are directly or indirectly associated with the cytoskeleton. We report the identification and characterization of a rice seed protein that possesses both RNA and microtubule binding activities. In vitro UV cross-linking assays indicated that this protein binds to all mRNA sequences tested, although there was evidence for preferential binding to RNAs that contained A-C nucleotide sequence motifs. The protein was purified to homogeneity using a two-step procedure, and amino acid sequencing identified it as the multifunctional protein (MFP), a peroxisomal enzyme known to possess a number of activities involved in the beta-oxidation of fatty acids. The recombinant version of this rice MFP binds to RNA in UV cross-linking and gel mobility shift experiments, co-sediments specifically with microtubules, and possesses at least two enzymatic activities involved in peroxisomal fatty acid beta-oxidation. Taken together these data suggest that MFP has an important role in mRNA physiology in the cytoplasm, perhaps in regulating the localization or translation of mRNAs through an interaction with microtubules, in addition to its peroxisomal function. 相似文献
995.
A rapid, sensitive, assay for enzymes that degrade heparin is described. The procedure is based on the interference of heparin with color development during the interaction of protein with the dye Coomassie brilliant blue. The loss of this property when the glycosaminoglycan is degraded by heparinase can be used to quantify activity of the enzyme in pure form, or in complex biological samples such as tissue homogenates or serum. The assay is also suitable for studying dependence of heparinase activity under conditions such as varying pH and temperature. 相似文献
996.
Conventional amperometric alcohol electrodes were constructed with oxygen- and hydrogen peroxide-base sensors and a much improved electrode was designed by placing a hydrophobic, gas-permeable membrane over the conventional hydrogen peroxide-based alcohol electrode. The immobilization of alcohol oxidase with glutaraldehyde was also studied and optimized. The upper linear ranges of the conventional and newly designed alcohol electrodes were 0.02 and 0.5% ethanol, respectively. The hydrophobic membrane of the new design eliminated the classical electrochemical interferences of hydrogen peroxide-based electrodes and the typical pH dependence of enzymatic systems. 相似文献
997.
Procedure and Analysis of a Useful Method in Determining Mycelial Dry Weights from Agar Plates
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The evaluation of growth by dry weight determination of fungus mycelium for agar plates was examined. The data obtained were statistically analyzed. This method was shown to be sufficiently accurate to be used as an investigative tool. 相似文献
998.
999.