全文获取类型
收费全文 | 1059篇 |
免费 | 151篇 |
出版年
2023年 | 5篇 |
2022年 | 11篇 |
2021年 | 18篇 |
2020年 | 16篇 |
2019年 | 5篇 |
2018年 | 19篇 |
2017年 | 17篇 |
2016年 | 35篇 |
2015年 | 55篇 |
2014年 | 55篇 |
2013年 | 82篇 |
2012年 | 56篇 |
2011年 | 42篇 |
2010年 | 37篇 |
2009年 | 48篇 |
2008年 | 44篇 |
2007年 | 49篇 |
2006年 | 34篇 |
2005年 | 43篇 |
2004年 | 49篇 |
2003年 | 33篇 |
2002年 | 37篇 |
2001年 | 32篇 |
2000年 | 36篇 |
1999年 | 31篇 |
1998年 | 20篇 |
1997年 | 16篇 |
1996年 | 20篇 |
1995年 | 14篇 |
1994年 | 19篇 |
1993年 | 15篇 |
1992年 | 20篇 |
1991年 | 15篇 |
1990年 | 16篇 |
1989年 | 15篇 |
1988年 | 16篇 |
1987年 | 11篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1979年 | 9篇 |
1978年 | 13篇 |
1976年 | 7篇 |
1975年 | 5篇 |
1973年 | 4篇 |
1967年 | 6篇 |
1928年 | 3篇 |
排序方式: 共有1210条查询结果,搜索用时 250 毫秒
1.
2.
Stimulation of secretion in exocrine secretory glands leads to the phosphorylation of a 22-kDa membrane protein (protein III) whose function is still unknown [Jahn et al. (1980) Eur. J. Biochem. 112, 345-352; Jahn & S?ling (1980) Proc. Natl Acad. Sci. USA 78, 6903-6906]. This report describes the comparison of this protein with phosphorylated membrane proteins of similar molecular mass in platelets and liver. Incubation of platelets with agents which raise the intracellular cAMP concentration results in the phosphorylation of a 22-kDa protein which is also phosphorylated in membrane preparations by endogenous kinases or by exogenous cAMP-dependent protein kinase. It is shown that this protein is distinct from protein III although both proteins have the same molecular mass and are substrates of cAMP-dependent protein kinase. In contrast to platelets, protein III could be demonstrated in liver microsomes. This indicates that the function of protein III is not exclusively linked to the stimulus-secretion coupling in exocrine cells. 相似文献
3.
4.
Zusammenfassung 1. Das Tauchen als Methode zur Untersuchung von Plankton und Echostreuschichten wird durch vier Beispiele erläutert: (a) Visuelle Beobachtungen an Wasserschichtungen und Grenzschichten durch Schwimmtaucher. (b) Untersuchung von Echostreuschichten durch Freitaucher, wobei sich ergab, daß angesammeltes biogenes Material in den untersuchten Sprung- beziehungsweise Streuschichten die Schallreflektion nicht beeinflußt. (c) Beobachtung von Großplankton und Feststellung von Planktonund Sestonkonzentrationen beim Tauchen mit dem Bathyscaph. (d) Untersuchung der Tiefenstreuschicht (deep scattering layer) durch Beobachtung der Vertikalwanderung bestimmter Arten des Großplanktons mit den Tauchbooten Bathyscaph und Soucoupe Plongeante. Physonectide Siphonophoren und Myctophiden standen in deutlicher Beziehung zur Tiefenstreuschicht und wurden als Echogeber erkannt.2. Die Möglichkeiten, von Tauchbooten aus quantitative und qualitative Proben von Plankton und auch vom Benthos zu nehmen, sind zur Zeit noch unzureichend. Die Entwicklung entsprechender Geräte für den wahlweisen und mehrfachen Einsatz bei demselben Tauchgang wird empfohlen.
Diving observations on plankton and on scattering layers
Diving techniques are employed as a research tool in plankton investigations carried out in shallow water of the western Baltic Sea. Observations and samplings were made by skin divers on scattering layers corresponding to the discontinuity layers. Biogene materials, sometimes concentrated at the thermocline, are not responsible for this special kind of scattering, but rather discontinuity of salinity and temperature (Lenz 1965). For observations in deep water the use of undersea vehicles is recommended. From the Bathyscaph and the diving saucer, single plankton organisms and plankton concentrations were observed (e. g.Bernard 1958); investigations on the deep scattering layer have shown physonectid siphonophores and myctophids to be scatterers (Barham 1966). The equipment for sampling plankton and benthos from undersea vehicles is poorly developed. We need urgently gear for quantitative and qualitative sampling and for manifold use during single dives, i. e., multiple sampling gear and magazins for storage of samples.相似文献
5.
Using ethnographic data collected in a second grade classroom over the course of a school year, this paper describes the ways in which one school's discourse of liberalism is deleteriously deployed. We view the school's discipline creed as emblematic of the school's liberal curriculum, and interrogate the effects on four African American boys in the classroom when the school enacts this creed. Despite the agency that these boys obviously had, they were unable to control the ways in which they were placed at a structural disadvantage and manipulated by a system far more powerful than they were. The results were that these four boys suffered. Not only did the intended liberal curriculum fail to be translated fully into the enacted curriculum, the liberal underpinnings of this curriculum precluded teachers and students from taking any critical stance. 相似文献
6.
Blastomycosis was fatal to a wild wolf in Minnesota, and serologic evidence of blastomycosis was found in a Wisconsin wolf. No unusual movements were detected in the Minnesota animal from October 1983 through October 1985. However, by early December 1985, this wolf was weak and debilitated, and it perished on 14 December after approaching a human residence. 相似文献
7.
Excised cotyledons of Pinus radiata D. Don cultured under shoot-forming(plus benzyladenine) and non shoot-forming (minus benzyladenine)conditions for 10 and 21 days were fed U-[14C]-glucose for 3h in the light followed by a 3 h chase period. The labellingof individual metabolites as well as 14C incorporation intoprotein was assessed. It was found that the general metabolicpatterns were qualitatively the same in shoot-forming and nonshoot-forming conditions, however, metabolism leading to respirationas well as to the synthesis of some amino acids and proteinsynthesis was enhanced in the shoot-forming cultures. (Received February 16, 1987; Accepted July 8, 1987) 相似文献
8.
Comparative yields of T-2 toxin and related trichothecenes from five toxicologically important strains of Fusarium sporotrichioides. 总被引:2,自引:1,他引:1
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 range and comparative yields of T-2 toxin and related trichothecenes from five toxicologically important strains of Fusarium sporotrichioides, i.e., NRRL 3299, NRRL 3510, M-1-1, HPB 071178-13, and F-38, were determined. Lyophilized cultures of the five strains maintained in the International Toxic Fusarium Reference Collection were used to inoculate autoclaved corn kernels. Corn cultures were incubated at 15 degrees C for 21 days and analyzed for trichothecenes by thin-layer chromatography and capillary gas chromatography. All five strains produced T-2 toxin, HT-2 toxin, T-2 triol, and neosolaniol. Two strains also produced T-2 tetraol, and two others produced diacetoxyscirpenol. The highest producer of T-2 toxin (1,300 mg/kg), HT-2 toxin (200 mg/kg), T-2 triol (1.9 mg/kg), and neosolaniol (170 mg/kg) was NRRL 3510, which was originally isolated from millet associated with outbreaks of alimentary toxic aleukia in the USSR. The second highest producer of T-2 toxin (930 mg/kg) was NRRL 3299. The other three strains produced T-2 toxin at levels ranging from 130 to 660 mg/kg. Thus, the five strains differed considerably in the amounts of T-2 toxin and other trichothecenes produced under identical laboratory conditions. These strains are being maintained under optimal conditions for the preservation of Fusarium cultures and are available from the Fusarium Research Center, The Pennsylvania State University, University Park. 相似文献
9.
Teresa Thiel 《Archives of microbiology》1988,149(5):466-470
The amino acid leucine was transported by the cyanobacterium Anabaena variabilis. The K
m for transport was 10.8 M; the V
max was 8.7 nmoles min–1 mg–1 chlorophyll a. Transport of leucine was energy dependent: uptake of leucine was inhibited in the dark, and by DCMU and cyanide. Transport was neither dependent on nor enhanced by Na+. Prior growth of cells with leucine did not repress transport of [14C]-leucine. Alanine, glycine, valine, and methionine were strong competitive inhibitors of leucine uptake; serine, threonine, isoleucine, norleucine, and d-alanine competitively inhibited to a lesser degree. Other amino acids or amino acid analogues, including d-leucine, -aminoisobutyrate, and d-serine did not inhibit the transport of leucine.Abbreviations Chl a
chlorophyll a
- DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- TES
N-tris(hydroxymethyl)-2-aminoethane-sulfonic acid
- TCA
trichloroacetic acid
- Tris
N-tris(hydroxymethyl)aminoethane 相似文献
10.
Richard W. Joy IV Kamlesh R. Patel Trevor A. Thorpe 《Plant Cell, Tissue and Organ Culture》1988,13(3):219-228
The effect of ascorbic acid on growth and shoot formation in callus cultures of tobacco (Nicotiana tabacum L.) was investigated, using young (4–12 subcultures) and old (more than 30 subcultures) tissue. It was found that ascorbate, at levels of 4–8×10-4M, enhanced shoot formation in both young and old callus. Treatment with ascorbate also speeded up the shoot-forming process. In addition, ascorbate completely reversed the inhibition of shoot formation by gibberellic acid in young callus, but was less effective in old callus. 相似文献