全文获取类型
收费全文 | 8188篇 |
免费 | 772篇 |
国内免费 | 9篇 |
出版年
2022年 | 53篇 |
2021年 | 121篇 |
2020年 | 71篇 |
2019年 | 118篇 |
2018年 | 109篇 |
2017年 | 89篇 |
2016年 | 165篇 |
2015年 | 247篇 |
2014年 | 277篇 |
2013年 | 358篇 |
2012年 | 432篇 |
2011年 | 415篇 |
2010年 | 242篇 |
2009年 | 226篇 |
2008年 | 350篇 |
2007年 | 337篇 |
2006年 | 336篇 |
2005年 | 323篇 |
2004年 | 312篇 |
2003年 | 298篇 |
2002年 | 291篇 |
2001年 | 108篇 |
2000年 | 92篇 |
1999年 | 111篇 |
1998年 | 104篇 |
1997年 | 70篇 |
1996年 | 78篇 |
1995年 | 69篇 |
1994年 | 78篇 |
1993年 | 64篇 |
1992年 | 91篇 |
1991年 | 103篇 |
1990年 | 91篇 |
1989年 | 75篇 |
1988年 | 64篇 |
1987年 | 83篇 |
1986年 | 68篇 |
1985年 | 63篇 |
1984年 | 98篇 |
1983年 | 76篇 |
1982年 | 89篇 |
1981年 | 75篇 |
1980年 | 105篇 |
1979年 | 69篇 |
1978年 | 84篇 |
1977年 | 81篇 |
1976年 | 69篇 |
1975年 | 64篇 |
1974年 | 68篇 |
1973年 | 82篇 |
排序方式: 共有8969条查询结果,搜索用时 15 毫秒
251.
D Servent C Ducrocq Y Henry A Guissani M Lenfant 《Biochimica et biophysica acta》1991,1074(2):320-325
We have demonstrated that a filamentous fungus Phanerochaete chrysosporium converts glyceryl trinitrate (GTN) into its di- and mononitrate derivatives concurrently with the formation of nitric oxide detected by electron paramagnetic resonance (EPR), and the formation of nitrite. The metabolisms of nitrite and nitrate by the fungus are evaluated and taken into account when considering GTN degradation. Lack of evidence for nitrate formation from GTN suggests that an esterase-type activity is not involved. Furthermore, the kinetics of appearance of the hemoprotein-NO and non-heme protein-NO (FeS-NO) complexes indicate that an enzymatic process producing NO directly from GTN may be involved concurrently with a glutathione transferase-like system. 相似文献
252.
Thomas R. Clark Henry L. Ehrlich 《Journal of industrial microbiology & biotechnology》1992,9(3-4):213-218
Summary Copper contained in a solid industrial waste produced in a silicone manufacturing process was leached with spent iron medium from aThiobacillus ferrooxidans culture. Most effective leaching was observed in a continuously fed, dual reactor system. Spent iron medium was generated by growingT. ferrooxidans in 0.9 K iron medium at pH 1.5 in the first reactor, and was transferred to a second reactor in which it leached the copper from the waste. Leaching was effective at a pulp density of the waste material as high as 20%. In experiments run at a pulp density of 2.5%, the spent iron medium was most efficient in leaching copper when it was first diluted 100-fold with a mineral salts solution at pH 1.5. Removal of the copper from the waste appeared to involve its displacement by acid, dissolved mineral salts, and ferric iron. Potentials for practical application of this process are discussed. 相似文献
253.
254.
Bilayers were formed at the tip of microelectrodes from a suspension of proteoliposomes derived from wild-type and porin-deficient mutant yeast mitochondria. In both preparations, identical cationic channels of large conductance were recorded. This result rules out any relationship between this channel and the outer membrane voltage-dependent anion channel, the activity of which is carried by porin. The ionic selectivity and the voltage-dependence of the yeast cationic channel suggest that it is related to that recently described in mammalian mitochondria. This hypothesis is further supported by the fact that both channels are blocked by a mitochondrial addressing peptide. 相似文献
255.
256.
Henry Khachaturian Stanley J. Watson Michael E. Lewis David Coy Avram Goldstein Huda Akil 《Peptides》1982,3(6):941-954
The distribution of dynorphin in the central nervous system was investigated in rats pretreated with relatively high doses (300–400 μg) of colchicine administered intracerebroventricularly. To circumvent the problems of antibody cross-reactivity, antisera were generated against different portions as well as the full dynorphin molecule (i.e., residues 1–13, 7–17, or 1–17). For comparison, antisera to [Leu]enkephalin (residues 1–5) were also utilized. Dynorphin was found to be widely distributed throughout the neuraxis. Immunoreactive neuronal perikarya exist in hypothalamic magnocellular nuclei, periaqueductal gray, scattered reticular formation sites, and other brain stem nuclei, as well as in spinal cord. Additionally, dynorphin-positive fibers or terminals occur in the cerebral cortex, olfactory bulb, nucleus accumbens, caudate-putamen, globus pallidus, hypothalamus, substantia nigra, periaqueductal gray, many brain stem sties, and the spinal cord. In many areas studied, dynorphin and enkephalin appeared to form parallel but probably separate anatomical systems. The results suggest that dynorphin occurs in neuronal systems that are immunocytochemically distinct from those containing other opioid peptides. 相似文献
257.
5.8 S RNA-protein complexes were prepared using purified yeast 5.8 S RNA and proteins from the large ribosomal subunit of rat liver. Formation of such hybrid complexes, as measured by Millipore filtration, was dependent on protein concentration. Binding of proteins to the RNA could approach saturation. Such complexes were isolated from sucrose density gradient centrifugation and shown to contain proteins L6, L8, L19, L35 and L35a. These proteins were identified by their molecular weights on polyacrylamide gels containing dodecylsulfate and their mobilities on two dimensional polyacrylamide gels. 相似文献
258.
259.
Spores ofNosema locustae Canning were applied with aerial equipment for experimental control of the Mormon cricket,Anabrus simplex Haldeman. The application resulted in infections in crickets during the season of application and the season following application. Spores were observed in cricket feces which indicated probable vertical transmission between generations. Reduced densities of crickets during the second season suggested effective control byN. locustae. 相似文献
260.
Summary Dictyosomes in three higher plant cell secretory systems,Zea root cap cells,Tradescantia pollen tubes and digestive glands ofDionaea fly traps, are shown to possess a structural polarity in terms of either the production of secretory vesicles, or the reaction of individual cisternae to the osmium-zinc-iodide impregnation procedure. These observations contradict previous claims that higher plant dictyosomes lack structural polarity. Doubts about the applicability of the endomembrane flow concept to higher plant cell dictyosomes are discussed in relation to the relative balance between carbohydrate and protein in secreted products. The lack of dictyosome-associated endoplasmic reticulum in some of these plant cell systems is confirmed. 相似文献