全文获取类型
收费全文 | 406047篇 |
免费 | 46219篇 |
国内免费 | 172篇 |
出版年
2018年 | 3503篇 |
2017年 | 3492篇 |
2016年 | 4694篇 |
2015年 | 6244篇 |
2014年 | 7267篇 |
2013年 | 10850篇 |
2012年 | 12140篇 |
2011年 | 12263篇 |
2010年 | 8207篇 |
2009年 | 7661篇 |
2008年 | 11138篇 |
2007年 | 11283篇 |
2006年 | 10862篇 |
2005年 | 10254篇 |
2004年 | 10153篇 |
2003年 | 9847篇 |
2002年 | 9590篇 |
2001年 | 18895篇 |
2000年 | 19082篇 |
1999年 | 15495篇 |
1998年 | 5427篇 |
1997年 | 5691篇 |
1996年 | 5509篇 |
1995年 | 5004篇 |
1994年 | 5119篇 |
1993年 | 4981篇 |
1992年 | 12925篇 |
1991年 | 12342篇 |
1990年 | 12284篇 |
1989年 | 12244篇 |
1988年 | 11145篇 |
1987年 | 10605篇 |
1986年 | 9833篇 |
1985年 | 9872篇 |
1984年 | 8000篇 |
1983年 | 6962篇 |
1982年 | 5294篇 |
1981年 | 4672篇 |
1980年 | 4550篇 |
1979年 | 7663篇 |
1978年 | 5932篇 |
1977年 | 5290篇 |
1976年 | 5113篇 |
1975年 | 5529篇 |
1974年 | 5779篇 |
1973年 | 5701篇 |
1972年 | 5162篇 |
1971年 | 4561篇 |
1970年 | 4032篇 |
1969年 | 3732篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
871.
Amphotericin B (AmB) increased unidirectional Na transport and net transcellular sodium movements across the skin of the frog, Rana pipiens, when added to the solution bathing the corium side, but not from the outer epidermal surface. The AmB response was prevented with pretreatment with amiloride, ouabain and mucosal sodium substitution. Alteration in pH markedly reduced the permeability changes induced by AmB. AmB did not interfere with the increase in sodium transport induced by antidiuretic hormone. The present study demonstrates that AmB interacts with the skin of the frog, Rana pipiens, from the corium side specifically increasing transepithelial sodium transport. The increase in transport apparently occurs through the existing sodium pathway. 相似文献
872.
P Couillin R Mollicone M C Grisard A Gibaud N Ravisé J Feingold R Oriol 《Cytogenetics and cell genetics》1991,56(2):108-111
Seventy-one human x mouse hybrid cell lines were used to map the locus of a human alpha-3-fucosyltransferase to 11q. The enzyme transfers fucose onto H type 2 more efficiently than onto sialyl-N-acetyllactosamine, suggesting that it is the myeloid type of alpha-3-fucosyltransferase (Mollicone et al., 1990), which makes the 3-fucosyllactosamine epitope on polymorphonuclear cells and monocytes. This epitope is also known as CD15 (Tetteroo et al., 1987). 相似文献
873.
I. Albesa P. Bogdanov A. Eraso N.R. Sperandeo M.M. de Bertorello 《Journal of applied microbiology》1995,78(4):373-377
I. ALBESA, P. BOGDANOV, A. ERASO, N.R. SPERANDEO AND M.M. DE BERTORELLO. 1995. The antibiotic activity of new synthetic isoxazolylnaphthoquinone imines was studied. Pseudomonas aeruginosa ATCC 27853 and Escherichia coli ATCC 25922 were resistant to the four compounds studied (MIC > 128 µg ml−1 ), but Staphylococcus aureus ATCC 25923, ATCC 29213 and 30 clinical isolates of Staph. aureus were inhibited by 2-hydroxy- N -(3,4-dimethyl-5-isoxazolyl)-1,4-naphthoquinone-4-imine (I). This compound diminished bloodstream infection of mice injected i.m. with Staph. aureus; septicaemia decayed significantly when I was applied at the beginning of the infection while when I was given 3 d after bacterial challenge, a significant protection was afforded. Bactericidal activity in serum increased during the 5 h after I was administered i.p.
The acetyl derivative of I had a high MIC but when inoculated orally in mice decreased the Staph. aureus counts in circulation. This protection occurred only when the schedule of administration started close to the bacterial challenge. Antibiotic activity in vivo may be associated with in vitro effects. 相似文献
The acetyl derivative of I had a high MIC but when inoculated orally in mice decreased the Staph. aureus counts in circulation. This protection occurred only when the schedule of administration started close to the bacterial challenge. Antibiotic activity in vivo may be associated with in vitro effects. 相似文献
874.
M A Taylor K A Pratt D F Revell K C Baker I G Sumner P W Goodenough 《Protein engineering》1992,5(5):455-459
For the first time the pro-form of a recombinant cysteine proteinase has been expressed at a high level in Escherichia coli. This inactive precursor can subsequently be processed to yield active enzyme. Sufficient protein can be produced using this system for X-ray crystallographic structure studies of engineered proteinases. A cDNA clone encoding propapain, a precursor of the papaya proteinase, papain, was expressed in E. coli using a T7 polymerase expression system. Insoluble recombinant protein was solubilized in 6 M guanidine hydrochloride and 10 mM dithiothreitol, at pH 8.6. A protein-glutathione mixed disulphide was formed by dilution into oxidized glutathione and 6 M GuHCl, also at pH 8.6. Final refolding and disulphide bond formation was induced by dilution into 3 mM cysteine at pH 8.6. Renatured propapain was processed to active papain at pH 4.0 in the presence of excess cysteine. Final processing could be inhibited by the specific cysteine proteinase inhibitors E64 and leupeptin, but not by pepstatin, PMSF or EDTA. This indicates that final processing was due to a cysteine proteinase and suggests that an autocatalytic event is required for papain maturation. 相似文献
875.
876.
E. Golomer P. Dupui H. Monod 《European journal of applied physiology and occupational physiology》1997,76(2):140-144
We investigated the effects of maturation on the dynamic body sways of healthy girls. Prepubertal and postpubertal girls
practising professional physical activities requiring a good ability to maintain equilibrium (acrobats and dancers) were asked
to stand on a free seesaw platform and the results compared to those for untrained age-matched girls. This platform (stabilometer)
allows self-induced body sways. Stabilograms were obtained by a double integration of the angular acceleration from the recordings
of the platform sways made with an accelerometer. Fast Fourier transform processing of stabilograms allowed spectral frequency
analysis. The total spectrum energy and the energies of three frequency bands (0–0.5 Hz, 0.5–2 Hz, 2–20 Hz) were determined.
ANOVA showed that, for all groups of different equilibrium activity and independent of visual input, prepubertal girls had
higher energy values than postpubertal girls in the 0- to 0.5-Hz band whereas the opposite was true for 0.5- to 2-Hz band.
Ballet dancers were more dependent than acrobats on visual inputs for the regulation of their postural control but were less
dependent than untrained girls at both ages. Maturation seemed to shift body sways towards higher frequencies and the utilization
of the cues of postural control was different according to the type of equilibrium activity practised by the subjects.
Accepted: 7 February 1997 相似文献
877.
878.
P Sullivan 《CMAJ》1990,142(11):1309-1310
879.
880.