全文获取类型
收费全文 | 1428篇 |
免费 | 68篇 |
国内免费 | 4篇 |
出版年
2021年 | 16篇 |
2020年 | 4篇 |
2019年 | 12篇 |
2018年 | 22篇 |
2017年 | 9篇 |
2016年 | 24篇 |
2015年 | 39篇 |
2014年 | 52篇 |
2013年 | 84篇 |
2012年 | 76篇 |
2011年 | 74篇 |
2010年 | 59篇 |
2009年 | 42篇 |
2008年 | 102篇 |
2007年 | 88篇 |
2006年 | 90篇 |
2005年 | 87篇 |
2004年 | 89篇 |
2003年 | 92篇 |
2002年 | 64篇 |
2001年 | 15篇 |
2000年 | 11篇 |
1999年 | 16篇 |
1998年 | 21篇 |
1997年 | 26篇 |
1996年 | 18篇 |
1995年 | 30篇 |
1994年 | 24篇 |
1993年 | 22篇 |
1992年 | 19篇 |
1991年 | 10篇 |
1990年 | 10篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 18篇 |
1983年 | 10篇 |
1982年 | 17篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1976年 | 9篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1971年 | 3篇 |
1970年 | 3篇 |
排序方式: 共有1500条查询结果,搜索用时 406 毫秒
21.
Low-humidity treatment triggered an increase of the thallus area and the chlorophyll content in the following high-humidity
condition. When low-humidity treatment for 4 days was intercalated in high-humidity conditions every 16 days, the thallus
area increased 40% in 76 days. 相似文献
22.
Shinji Hosoi Mitsuo Satoh Hiromasa Miyaji Tatsunari Nishi Tamio Mizukami Mamoru Hasegawa Seiga Itoh Tatsuya tamaoki 《Cytotechnology》1995,19(1):1-10
Pro-UKS1 was designed as a thrombin-resistant derivative of pro-urokinase (pro-UK) by introducing a glycosylation site using site-directed mutagenesis. An expression plasmid for pro-UKS1, pMo1UKS1SEd1-5, was constructed and introduced into Namalwa KJM-1 cells (Hosoiet al., 1988), and cells resistant to G418 and Methotrexate (MTX) were obtained. Amongst them, the highest pro-UKS1 producer (resistant to 500 nM of MTX), clone 41-8, was selected and further characterized. Clone 41-8 was cultured in serum-free ITPSGF medium (Hosoiet al., 1988). Under the conventional conditions, the concentration of pro-UKS1 reached 26 g ml–1. Addition of glucose and tri-iodothyronine (T3) improved productivity, and the maximal productivity of pro-UKS1 was 67 g ml–1 day–1. In this conditioned medium, content of pro-UKS1 was above 80% of total proteins.Abbreviations BSA
bovine serum albumin
- dhfr
dihydrofolate reductase
- HEPES
4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
- kb
kilobase pairs
- kDa
kilodaltons
- MTX
Methotrexate
- PBS
phosphate buffered saline
- pro-UK
pro-urokinase
- SDS-PAGE
sodium dodecyl sulfate-polyacrylamide gel electrophoresis
- T3
tri-iodothyronine
- Tween-PBS
phosphate buffered saline containing 0.05% Tween 80 相似文献
23.
The growth of lichens in the field is slow and their cultivation is generally thought to be difficult. We studied the effects
of environmental conditions and culture solutions on the growth of a lichen, and found that growth ofParmotrema tinctorum (Nyl.) Hale in growth cabinets was possible. The thallus area increased by about 20% monthly when the lichen was soaked in
a culture solution for 90 min every four days and then grown at 100% relative humidity when the temperature in the growth
cabinet was 20C and illumination was at 12 W/m2 for 16 hr daily. 相似文献
24.
Immunochemical characterisation and epitope mapping of a novel fimbrial protein (Pg-II fimbria) of Porphyromonas gingivalis 总被引:2,自引:0,他引:2
Tomohiko Ogawa Kenji Yasuda Keiko Yamada Hideharu Mori Keiko Ochiai Mamoru Hasegawa 《FEMS immunology and medical microbiology》1995,11(3):247-255
Abstract Mouse monoclonal antibody (mAb) Pgf-II specific for a 72-kDa major cell-surface protein (72K-CSP) derived from Porphyromonas gingivalis OMZ 409 was prepared. Immunoblotting analysis revealed that mAb Pgf-II reacted with 72K-CSP but not with 41-kDa fimbrial subunit protein (41K-fimbrilin) derived from P. gingivalis 381. Electron microscopic observation revealed that P. gingivalis OMZ 409 possessed peritrichous, thin fimbriae on their surface. Immunogold electron microscopy also demonstrated that mAb Pgf-II bound to the 72K-CSP examined with the gold particles arranged along the fibril array originating from the cell surface of the bacteria. These findings suggested that P. gingivalis 72K-CSP was identifiable as another fimbriae (termed Pg-II fimbriae) different from the fimbriae (termed Pg-I fimbriae) composed of a 41K-fimbrilin. Using multipin peptide synthesis technology, 102 sequential overlapping peptides covering the entire 514 amino-acid stretch of Pg-II fimbriae were synthesised. Seven immunodominant regions within Pg-II fimbrial protein molecule, which definitely reacted with the serum of patients with periodontal diseases, were detected. 相似文献
25.
Masao Hyodo Narushi Ito Kenshi Suzuki 《Biochemical and biophysical research communications》1984,122(3):1160-1165
The size of deoxynucleoside triphosphate pool in cultured mouse FM3A cells and mutator mutants isolated from this cell line was determined by high-pressure liquid chromatography after treatment of the cells with ultraviolet light, N-methyl-N′-nitro-N-nitrosoguanidine or mitomycin C. The results showed that, in all the FM3A cell clones, no large increase in the dATP or TTP pool was induced after treatment, while in some cases 40–50% decrease in dCTP pool was observed. It is concluded that the induction of large increase in dNTP pool is not the general effect of the mutagens. 相似文献
26.
Yukiyoshi Tamura Shigeharu Nakamura Hiroshi Fukui Mamoru Tabata 《Plant cell reports》1984,3(5):183-185
Clonal propagation of Stevia rebaudiana has been established by culturing stem-tips with a few leaf primordia on an agar medium supplemented with a high concentration (10 mg/l) of kinetin. Anatomical examination has suggested that these multiple shoots originate from a number of adventitious buds formed on the margin of the leaf. Innumerable shoots can be obtained by repeating the cycle of multiple-shoot formation from a single stem-tip of Stevia. These shoots produce roots when transferred to a medium containing NAA (0.1 mg/l) without kinetin. The regenerated plantlets can be transplanted to soil. 相似文献
27.
Tanaka Osamu; Nasu Yutaka; Takimoto Atsushi; Kugimoto Mamoru 《Plant & cell physiology》1982,23(7):1291-1296
The effect of copper on flowering and growth of Lemna paucicostata6746 and Lemna gibba G3 in a copper-containing medium is nullifiedby the addition of EDTA, ammonium ions or salicylic acid tothe medium or a decrease in its nitrate concentration. Thesefactors were examined for their effects on the absorption ofcopper by the plants. The addition of EDTA to the medium completelyinhibited the absorption of copper in both species, thus eliminatingthe copper effect. Ammonium ions also inhibited copper absorption,their effectiveness rising with their concentration. Loweringthe nitrate concentration in the medium nullified the coppereffect on flowering in L. paucicostata 6746, and the additionof salicylic acid to the medium also nullified the copper effectin L. gibba G3, both without affecting the absorption of copper. (Received June 7, 1982; Accepted August 27, 1982) 相似文献
28.
29.
Mamoru Watanabe 《Population Ecology》1981,23(1):74-93
The long-term population dynamics of the swallowtail butterfly, Papilio xuthus, were studied by means of life table analysis in a deforested area, where the host tree, Zanthoxylum ailanthoides, was growing. The number of eggs laid on host trees in the deforested area decreases as secondary succession progresses. When the trees were classified into three groups, i. e. tall, medium and short, according to their height relative to the surrounding vegetation, less eggs were laid on tall than on short host trees. Life tables for the natural populations in each generation were developed on the basis of mean values for 6 years. Eggs and larvae in early stages were attacked chiefly by small- and middle-sized predators, such as ants, spiders, bugs and orthopterids, while later stage larvae were attacked chiefly by birds or Polistes wasps. An inchneumonid wasp was the most important mortality factor in the pupal stage. Key-factor analysis was tested on the life table data of each immature stage. The late larval stage was a key stage, and most mortality factors were considered to operate independently. The test for density dependency did not show any tendencies. The analysis of variance in two-way classifications was carried out for the difference of survival rate among the tree groups. It was suggested that tall host trees were unsuitable for P. xuthus. The construction of life tables for artificially inoculated populations on large host trees showed that high physiological death rate were characteristic of such trees in comparison with natural populations on smaller trees. The characteristics of the population dynamics of P. xuthus in the deforested area are compared among some kinds of the habitat, and the interrelationship between P. xuthus and its host plant are discussed. 相似文献
30.
Induction of phenylalanine ammonia-lyase and increase in phenolics in lettuce leaves in relation to the development of russet spotting caused by ethylene 总被引:5,自引:1,他引:4 下载免费PDF全文
Russet spotting (RS), consisting of numerous small brown spots on the midrib of head lettuce (Lactuca sativa), is a physiological disorder induced by exposure to ethylene. In leaves suffering RS, the increase in spotting was accompanied by a parallel increase in the amount of phenolic compounds. Of these, chlorogenic acid and isochlorogenic acid were identified. Ethylene induced high phenylalanine ammonia-lyase (PAL) activity and RS formation in the susceptible cultivar Salinas, but not in the resistant cultivar Calmar. In the absence of ethylene neither significant PAL induction nor RS occurred. No correlation was found between the increase in polyphenol oxidase or peroxidase and the development of RS. The increase in PAL activity, however, was closely correlated with the development of RS. The increase in PAL activity preceded the development of RS, and the extent of RS was directly related to the level of PAL. Three temperatures (0.5, 5.5, and 12.5 C) were compared on the basis of their influence on both RS and PAL induction. At the lowest temperature (0.5 C) neither PAL induction nor RS occurred to a significant extent. At the highest temperature (12.5 C) an initial rapid increase in PAL activity and an earlier development of spotting were observed, but subsequently there was a decrease in both PAL activity and the rate of development of RS. At the medium temperature (5.5 C) both PAL activity and RS increased progresively with time. The decline of PAL activity at a higher temperature might be attributed to inactivation of the enzyme. Thus, a temperature favorable for induction of PAL activity by ethylene was also favorable for RS. These observations indicate a close interrelationship between the induction of PAL activity and the development of RS in response to ethylene, and suggest a causal relationship between the two events. PAL serves as a useful biochemical marker for the RS reaction. 相似文献