全文获取类型
收费全文 | 1833篇 |
免费 | 117篇 |
国内免费 | 3篇 |
出版年
2023年 | 13篇 |
2022年 | 36篇 |
2021年 | 68篇 |
2020年 | 28篇 |
2019年 | 32篇 |
2018年 | 52篇 |
2017年 | 36篇 |
2016年 | 53篇 |
2015年 | 73篇 |
2014年 | 85篇 |
2013年 | 119篇 |
2012年 | 145篇 |
2011年 | 136篇 |
2010年 | 64篇 |
2009年 | 58篇 |
2008年 | 106篇 |
2007年 | 94篇 |
2006年 | 69篇 |
2005年 | 58篇 |
2004年 | 59篇 |
2003年 | 53篇 |
2002年 | 44篇 |
2001年 | 50篇 |
2000年 | 54篇 |
1999年 | 23篇 |
1998年 | 18篇 |
1997年 | 14篇 |
1996年 | 7篇 |
1995年 | 9篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 29篇 |
1991年 | 14篇 |
1990年 | 17篇 |
1989年 | 20篇 |
1988年 | 16篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 12篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1979年 | 15篇 |
1978年 | 11篇 |
1977年 | 9篇 |
1975年 | 7篇 |
1974年 | 6篇 |
1973年 | 7篇 |
1972年 | 12篇 |
1971年 | 8篇 |
1969年 | 16篇 |
排序方式: 共有1953条查询结果,搜索用时 15 毫秒
1.
Isolation and screening of potential actinobacteria for rapid composting of rice straw 总被引:2,自引:0,他引:2
Rice straw is produced as a by-product from rice cultivation, which is composed largely of lignocellulosic materials amenable
to general biodegradation. Lignocellulolytic actinobacteria can be used as a potential agent for rapid composting of bulky
rice straw. Twenty-five actinobacteria isolates were isolated from various in situ and in vitro rice straw compost sources.
Isolates A2, A4, A7, A9 and A24 were selected through enzymatic degradation of starch, cellulose and lignin followed by the
screening for their adaptability on rice straw powder amended media. The best adapted isolate (A7) was identified as Micromonospora
carbonacea. It was able to degrade cellulose, hemicelluloses and carbon significantly (P ≤ 0.05) over the control. C/N ratio was reduced to 18.1 from an initial value of 29.3 in 6 weeks of composting thus having
the potential to be used in large scale composting of rice straw. 相似文献
2.
3.
4.
D Kierek-Jaszczuk M Zurkowski E Sk?adanowska-Krzyzanowska K Tomaszewska-Guszkiewicz 《Animal blood groups and biochemical genetics》1979,10(1):15-18
Genetic variants of serum alkaline phosphatase were studied by the method of starch gel electrophoresis in the Z?otnicka Pstra breed of pigs. Two regions of alkaline phosphatase migration were observed. A single fraction in region I and four different phenotypes: AB, B, BC and BD in region II, were found. For AB, B and BC phenotypes the genetic control by three alleles AkpA, AkpB and AkpC is suggested. The observed segregation ratios in some cases deviated significantly from the expected ones. 相似文献
5.
Munirul Alam Shin-ichi Miyoshi Ikuyo Maruo Chiemi Ogawa Sumio Shinoda 《Microbiology and immunology》1994,38(6):467-470
The protease elaborated by Vibrio mimicus is known to possess hemagglutinating ability to chicken erythrocytes, the well-known HA/protease. A non-protease hemagglutinin (HA) with strong agglutinating ability towards rabbit erythrocytes was obtained from 32 hr culture supernatant of a pathogenic environmental strain of V. mimicus. This HA (V. mimicus HA: VMHA) appeared stable at relatively higher temperature and agglutinated the erythrocytes from rabbit, guinea pig and mouse but not the erythrocytes from chicken, bovine, horse and sheep. Simple sugars, metal ions and chelating agents failed to inhibit the activity of VMHA. The activity of VMHA was found to be sensitive to digestion by proteolytic enzymes including HA/protease. These results provide evidence for the existence of novel HA other than HA/protease in V. mimicus. 相似文献
6.
T Skórski M Kawalec J Kawiak 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》1987,25(1):23-27
The composition of peritoneal exudate and spleen cells of CD2F1 mice after fourfold i.p. administration of L 1210 leukemia cells treated with cyclophosphamide (L 1210-CY cells) were examined. The number of cells in peritoneal cavity did not increase, however, the spleen weight rose after administration of L 1210-CY cells. The per cent of lymphocytes T was increased 2.5 times but the content of macrophages and lymphocytes B was normal in the peritoneal cavity after L 1210-CY cells injections. In the spleen an 1.4 times increase of the per cent of lymphocytes B, but normal level of macrophages and lymphocytes T were observed. 相似文献
7.
8.
9.
C L Cohn J R Sprinkle J Alam M Hermodson T Meyer D W Krogmann 《Archives of biochemistry and biophysics》1989,270(1):227-235
The low-potential cytochrome c550 has been purified from the cyanobacterium Microcystis aeruginosa and its amino acid sequence has been determined. The protein contains 135 amino acid residues with the Cys-X-X-Cys-His heme binding site at residues 37 to 41. The sequence from residue 28 to 45 shows similarity to cytochrome c553 residues 1 to 18 when the heme binding sites are aligned. Another region of similarity is in the carboxyl-terminal regions of these two proteins. The two aligning regions of cytochrome c553 correspond to helical segments in other related cytochromes. A partial sequence of cytochrome c550 from Aphanizomenon flos-aquae was obtained and showed a 48% identity to the sequence of the M. aeruginosa cytochrome. The single methionine residue in cytochrome c550 of M. aeruginosa occurs at position 119 but there is no methionine in this region in the A. flos-aquae cytochrome, indicating that methionine is not the sixth ligand to the heme iron atom. Histidine 92 is a possible sixth ligand in M. aeruginosa cytochrome c550. The far-uv circular dichroism spectrum indicates that this protein is approximately 17% alpha helix, 42% beta-pleated sheet, and 41% random coil. 相似文献
10.
Sarah Perreault M. Ather Ali Skúli Skúlason David L. G. Noakes 《Environmental Biology of Fishes》1990,27(2):131-137
Synopsis At high latitudes, such as in Iceland, the daily photoperiod varies from almost continuous darkness in winter to virtually constant light in summer. Previous studies of detailed retinal structure in vertebrates have shown significant daily and annual effects of photoperiod. We sampled arctic charr in Iceland during the summer, including fish that were both light- and dark-adapted, during both day and night. We observed retinomotor responses characteristic of light- and dark-adaptation, but found no difference in the number of synaptic ribbons in the retina. The morpho-physiological changes, appearing as retinomotor responses, are thus not expressed at the synaptic level. 相似文献