全文获取类型
收费全文 | 349篇 |
免费 | 55篇 |
国内免费 | 1篇 |
出版年
2022年 | 5篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 18篇 |
2014年 | 21篇 |
2013年 | 13篇 |
2012年 | 17篇 |
2011年 | 9篇 |
2010年 | 15篇 |
2009年 | 13篇 |
2008年 | 13篇 |
2007年 | 13篇 |
2006年 | 13篇 |
2005年 | 13篇 |
2004年 | 7篇 |
2003年 | 11篇 |
2002年 | 8篇 |
2001年 | 11篇 |
2000年 | 7篇 |
1999年 | 14篇 |
1998年 | 7篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 10篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1971年 | 6篇 |
1968年 | 3篇 |
1965年 | 3篇 |
1961年 | 2篇 |
1960年 | 2篇 |
排序方式: 共有405条查询结果,搜索用时 15 毫秒
1.
Petrobia harti (Ewing) developed more rapidly, deposited more eggs and lived longer onOxalis corniculata than onO. articulata. No development took place on several other recorded host plants. In the field this mite was most abundant during early summer. Males made up less than 10% of the population, and no diapause eggs were seen in the field.Petrobia tunisiae Manson developed on various winter Gramineae, produced about 17 non-diapause eggs during its first generation and mostly diapause eggs in the second. A few diapause eggs kept in the laboratory and dipped in chloroform hatched even after 3 years. A summer diapause is postulated for this species. 相似文献
2.
Cloned and expressed human Fc receptor for IgG mediates anti-CD3-dependent lymphoproliferation 总被引:15,自引:0,他引:15
G A Peltz M L Trounstine K W Moore 《Journal of immunology (Baltimore, Md. : 1950)》1988,141(6):1891-1896
We have utilized gene transfer experiments to investigate the role of a human monocyte receptor for IgG (Fc gamma RII) in mouse IgG1 anti-CD3 (Leu 4)-induced lymphoproliferation in vitro. Mouse Ltk- cells expressing human Fc gamma RII or a mutant of Fc gamma RII lacking the entire cytoplasmic domain of the receptor mediate anti-CD3-induced lymphoproliferation in cultures of adherent cell-depleted human PBMC. Expression of an Fc gamma RII mutant lacking transmembrane and cytoplasmic domains (soluble Fc gamma RII) in COS7 cells yielded a secreted receptor which retained affinity for IgG, even in the absence of the mutant receptor's N-linked oligosaccharides. Soluble Fc gamma RII inhibits rosette formation by human IgG-sensitized RBC and the Fc gamma RII-bearing cell line K562, but does not sitmulate anti-CD3-induced lymphoproliferation under the conditions tested. 相似文献
3.
Rhizoglyphus robini Claparède (Acari: Astigmata: Acaridae) is proposed as a model laboratory animal for biological, ecological, physiological and toxicological studies. The mite is easy and inexpensive to rear, quite fecund, convenient to manipulate, and may rapidly be raised to gram quantities. Examples are presented of its use in soil pest ecology and control studies, and in physiological, biochemical and toxicological investigations. Efforts to explore the induction of detoxification systems by various chemicals, and a demonstration of its control by solarization, are also described. 相似文献
4.
A control system has been devised for the maintenance of stable ammonium concentrations throughout a fedbatch fermentation. The control system is based on an ammonia gas-sensing electrode that monitors a pH-adjusted effluent stream from the fermentor. To overcome the time lag between the fermentor and the electrode, feedback control included metered flows of ammonium to both the fermentor and the electrode vessel. The system was used to study the growth of Escherichia coli B (ATCC 11303) at controlled ammonium concentrations of 5 to 200mM. Apparent specific growth rates, biomass and protein production, and glucose yields were essentially constant from 5 to 170mM. Above 170mM ammonium growth was inhibited. As ammonium concentration decreased from 170 to 5mM, ammonium yields increased from 1 to 24 g cell dry wt/g ammonium utilized. The results demonstrate that control of ammonium concentrations at levels so low that ammonium would be exhausted in batch fermentations can significantly increase overall ammonium yields. 相似文献
5.
Monoclonal antibodies against seven sites on the head and tail of Dictyostelium myosin 总被引:13,自引:9,他引:4
下载免费PDF全文
![点击此处可从《The Journal of cell biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ten monoclonal antibodies (My1-10) against Dictyostelium discoideum myosin were prepared and characterized. Nine bound to the 210-kD heavy chain and one (My8) bound to the 18-kD light chain. They defined six topographically distinct antigenic sites of the heavy chain. Five binding sites (the My1, My5, My10 site, and the My2, My3, My4, and My9 sites) are located on the rod portion of the myosin molecule. The position of the sixth site (the My6 and My7 site) is less certain, but it appears to be near the junction of the globular heads and the rod. Three of the antibodies (My2, My3, and My6) bound to myosin filaments in solution and could be sedimented in stoichiometric amounts with the filamentous myosin. In contrast, My4, which recognized a site on the rod, inhibited the polymerization of monomeric myosin into filaments. A single antibody (My6) affected the actin-activated ATPase of myosin. The nature of the effect depended on the valency of the antibody and the myosin. Bivalent IgG and F(ab')2 fragments of My6 inhibited the actin-activated ATPase of filamentous myosin by 50% whereas univalent Fab' fragments increased the activity by 50%. The actin-activated ATPase activity of the soluble chymotryptic fragment of myosin was increased 80-90% by both F(ab')2 and Fab' of My6. 相似文献
6.
A. Lacoursiere B. G. Thompson M. M. Kole D. Ward D. F. Gerson 《Applied microbiology and biotechnology》1986,23(5):404-406
Summary The effect of dissolved carbon dioxide concentration in the anaerobic growth of Escherichia coli was investigated. E. coli was grown anaerobically with the dissolved CO2 concentration controlled over the range from 8x10-6 M to 3.7x10-2 M in the liquid phase. The maximum specific growth rate was 0.75h-1 at 1.3x10-3 M CO2 and the maximum yield of cells on glucose was 0.32 at 1.75x10-4 M CO2. The maximum specific growth rate occurs close to the concentration of CO2 prevalent in the mammalian gut where E. coli naturally resides.Alberta Research Council contribution, paper 1364 相似文献
7.
Rapidly proliferating, polyclonally stimulated mouse spleen lymphocytes were separated by density-gradient unit-gravity sedimentation. The following measurements were made on each fraction: the average intracellular water volume, the distribution of DNA content by flow microfluorometry, the rate of 3H-thymidine incorporation, and the intracellular pH. Fractions of cells with a small average intracellular volume were predominately in G0 or G1 phase of the cell cycle, while fractions of larger cells had higher proportions of cells in S or G2. Multiple regression analysis of the data for both T and B lymphocytes indicated that the intracellular pH of cells in G0, G1, or G2 is around pH 7.2, and that the intracellular pH of cells in S phase of the cell cycle is around pH 7.4. 相似文献
8.
Lychees were surveyed in Queensland, Australia and in Guangdong Province and Hainan Island China, for natural enemies of the lychee erinose mite,Aceria litchii (Keifer), one of the most serious pests of lychee in Australia. A guild of seventeen predators, including ten species of phytoseiid mites, was associated with lychee erinose in Queensland. Six other predaceous mite species and a cecidomyiid larva,Arthrocnodax sp. were also part of the complex. Despite the apparent predation of most of the seventeen species recorded in Queensland onA. litchii, the pest continues to cause major problems. In China, whereA. litchii is a relatively minor pest, nine phytoseiid species were collected in lychee orchards. The value of introducing additional predators to Australia, especially from China, is discussed. 相似文献
9.
The prescribing of psychoactive drugs for 1431 chronically ill elderly patients being assessed for long-term institutional or community care was surveyed. Psychoactive drugs had been prescribed for about one quarter of the patients; benzodiazepines were the most frequently prescribed group. Judging from the extensive prescribing of flurazepam and chloral hydrate, commonly used hypnotics, the main reason psychoactive drugs were prescribed was to provide night-time sedation. Antidepressants and drugs promoted as useful in improving cognitive function were infrequently prescribed. Commendable prescribing practices included the infrequent use of "cerebral vasodilators" and barbiturates. Questionable prescribing practices included the infrequent use of tricyclic antidepressants in severely depressed patients and the use of tranquilizers in patients described by their attending physician as markedly or extremely withdrawn. 相似文献
10.
John Quagliarello M.D. Lars Cederqvist M.D. Bernard Steinetz Ph.D. Gerson Weiss M.D. 《Prostaglandins & other lipid mediators》1978,16(6):1003-1006
Relaxin, a peptide hormone produced only by the corpus luteum of pregnancy, can be used as a marker of luteal function in human pregnancy. Serum immunoreactive relaxin levels were measured serially in six women having second trimester abortions induced with intravaginal prostaglandin E2 (PGE2) suppositories. All patients aborted within 17 hours of the first suppository. No significant changes were detectable in serum relaxin levels in any of the patients. It is concluded that PGE2 does not interfere with the corpus luteum's ability to secrete relaxin in the second trimester of human pregnancy. 相似文献