全文获取类型
收费全文 | 3277篇 |
免费 | 289篇 |
国内免费 | 4篇 |
出版年
2023年 | 13篇 |
2022年 | 25篇 |
2021年 | 48篇 |
2020年 | 40篇 |
2019年 | 54篇 |
2018年 | 44篇 |
2017年 | 52篇 |
2016年 | 76篇 |
2015年 | 124篇 |
2014年 | 158篇 |
2013年 | 169篇 |
2012年 | 238篇 |
2011年 | 294篇 |
2010年 | 173篇 |
2009年 | 138篇 |
2008年 | 196篇 |
2007年 | 230篇 |
2006年 | 179篇 |
2005年 | 188篇 |
2004年 | 165篇 |
2003年 | 162篇 |
2002年 | 156篇 |
2001年 | 37篇 |
2000年 | 16篇 |
1999年 | 37篇 |
1998年 | 37篇 |
1997年 | 26篇 |
1996年 | 23篇 |
1995年 | 21篇 |
1994年 | 18篇 |
1993年 | 34篇 |
1992年 | 14篇 |
1991年 | 25篇 |
1990年 | 19篇 |
1989年 | 14篇 |
1988年 | 22篇 |
1987年 | 15篇 |
1986年 | 19篇 |
1985年 | 22篇 |
1984年 | 23篇 |
1983年 | 18篇 |
1982年 | 19篇 |
1981年 | 29篇 |
1980年 | 20篇 |
1979年 | 15篇 |
1977年 | 18篇 |
1976年 | 13篇 |
1975年 | 11篇 |
1974年 | 16篇 |
1973年 | 13篇 |
排序方式: 共有3570条查询结果,搜索用时 15 毫秒
21.
Gerard H. Markx Christopher L. Davey Douglas B. Kell Phillip Morris 《Journal of biotechnology》1991,20(3):279-290
A novel technique is described for the measurement of the volume fraction of biomass in a suspension by the simultaneous measurement of the conductivity of a suspension containing cells and of the medium in which the cells are suspended. The presence of non-conducting particulate matter in a suspension will cause the conductivity of a suspension to be decreased relative to that of the medium in which the particles are suspended. A simple equation (the Bruggeman equation) describes the relationship between the volume fraction of non-conducting particulate matter and the decrease in conductivity. The accuracy of this method for the determination of the biomass concentration of plant cells (Festuca arundinacea) in culture was shown. The method was successfully applied to the on-line determination of biomass concentrations during the growth of F. arundinacea cultures, and gave good agreement with biomass levels as determined from measurements of the radio-frequency dielectric permittivity of such cultures. 相似文献
22.
Phillip V. Tobias 《International Journal of Anthropology》1991,6(3):277-280
Having been approached from time to time by various museum, university and governmental authorities in Australia, California
and Scotland, I have set down some brief notes on the scientific, medical, dental and educational importance and value of
collections of recent human skeletons drawn from populations in all parts of the world.
This article does not pretend to completeness. It has been set down in the hope that it may be of assistance to those officiers
in charge of such collections and who may be pondering upon the worthwhileness of such collections being retained and maintained. 相似文献
23.
24.
25.
Christopher E. Taylor Philip W. Stashak George Caldes Benjamin Prescott B.J. Fowlkes Phillip J. Baker 《Cellular immunology》1984,83(1):26-33
Several lectins were tested for their capacity to alter the antibody response to type III pneumococcal polysaccharide (SSS-III). The antibody response was enhanced by concanavalin A (Con A), phytohemagglutinin (PHA), as well as lectins from Phytolacca americana (Pa-2), Pisum sativum (PSA), and Lens culinaris (LCH), when these lectins were given 2 days after immunization with SSS-III; however, suppression was obtained when Con A and Pa-2 were given at the time of immunization. By contrast the lectins from Vicia villosa (VVL) and Bauhinia purpurea (BPA) did not alter the antibody response. Since the lectins PSA and LCH bind to the same monosaccharide as Con A, whereas the other lectins bind to different monosaccharides, these findings indicate that there is no relationship between nominal monosaccharide specificity and the capacity to modulate the antibody response. Substantial increases in the magnitude of the IgG1 antibody response was noted after the administration of Con A whereas profound enhancement of IgG2a antibody response was noted after PHA was given. 相似文献
26.
Electrophysiological actions of somatostatin (SRIF) in hippocampus: Anin vitro study 总被引:1,自引:0,他引:1
Alan L. Mueller Dennis D. Kunkel Phillip A. Schwartzkroin 《Cellular and molecular neurobiology》1986,6(4):363-379
The electrophysiological actions of somatostatin (somatotropin release inhibiting factor; SRIF) were investigated in the in vitro hippocampal slice preparation. Intracellular recordings were obtained from pyramidal neurons in area CA1 in slices of hippocampus from guinea pigs and rabbits. Somatostatin, applied via micropressure ejection to CA1 pyramidal-cell somata, was primarily excitatory. The effects, however, were quite variable, with nearly all cells displaying pronounced tachyphylaxis. A majority of cells was depolarized by SRIF, but hyperpolarizations or biphasic depolarization/hyperpolarization responses were also recorded. Only minimal conductance changes were associated with the SRIF-induced voltage changes. Depletion of SRIF, by injection of the intact animal with cysteamine several hours before preparing slices, resulted in no obvious abnormalities in hippocampal slice electrophysiology. Our results obtained with application of exogenous SRIF are consistent with the concept that SRIF acts as an excitatory neurotransmitter/neuromodulator in hippocampus. However, our attempts to demonstrate endogenous SRIF action have thus far been unsuccessful. 相似文献
27.
Human Adenovirus Type 2 but Not Adenovirus Type 12 Is Mutagenic at the Hypoxanthine Phosphoribosyltransferase Locus of Cloned Rat Liver Epithelial Cells 总被引:2,自引:1,他引:1 下载免费PDF全文
Christos Paraskeva Carl Roberts Paul Biggs Phillip H. Gallimore 《Journal of virology》1983,46(1):131-136
Using resistance to the base analog 8-azaguanine as a genetic marker, we showed that adenovirus type 2, but not adenovirus type 12, is mutagenic at the hypoxanthine phosphoribosyltransferase locus of cloned diploid rat liver epithelial cells. Adenovirus type 2 increased the frequency of 8-azaguanine-resistant colonies by up to ninefold over the spontaneous frequency, depending on expression time and virus dose. 相似文献
28.
29.
Use of Erythrocytes Sensitized with Purified Pneumococcal Polysaccharides for the Assay of Antibody and Antibody-producing Cells 总被引:53,自引:2,他引:51 下载免费PDF全文
A method was described for the sensitization of erythrocytes with purified type-specific pneumococcal polysaccharide antigens using chromium chloride as a coupling agent. Erythrocytes so sensitized can be used in routine passive hemagglutination and hemolysis tests as well as in the technique of localized hemolysis-in-gel for the detection of specific antibody and specific antibody-producing cells, respectively. 相似文献
30.