全文获取类型
收费全文 | 2185篇 |
免费 | 188篇 |
出版年
2023年 | 12篇 |
2021年 | 42篇 |
2020年 | 26篇 |
2019年 | 26篇 |
2018年 | 32篇 |
2017年 | 41篇 |
2016年 | 50篇 |
2015年 | 96篇 |
2014年 | 106篇 |
2013年 | 124篇 |
2012年 | 178篇 |
2011年 | 156篇 |
2010年 | 105篇 |
2009年 | 113篇 |
2008年 | 132篇 |
2007年 | 141篇 |
2006年 | 120篇 |
2005年 | 110篇 |
2004年 | 105篇 |
2003年 | 97篇 |
2002年 | 85篇 |
2001年 | 27篇 |
2000年 | 14篇 |
1999年 | 16篇 |
1998年 | 24篇 |
1997年 | 9篇 |
1996年 | 19篇 |
1995年 | 15篇 |
1993年 | 16篇 |
1991年 | 10篇 |
1990年 | 14篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 12篇 |
1986年 | 12篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 10篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1979年 | 10篇 |
1978年 | 12篇 |
1977年 | 15篇 |
1976年 | 14篇 |
1974年 | 15篇 |
1973年 | 15篇 |
1972年 | 12篇 |
1971年 | 9篇 |
1970年 | 9篇 |
1967年 | 9篇 |
排序方式: 共有2373条查询结果,搜索用时 15 毫秒
11.
D Maharaj G S Fell B F Boyce J P Ng G D Smith J M Boulton-Jones R L Cumming J F Davidson 《BMJ (Clinical research ed.)》1987,295(6600):693-696
Aluminium balance studies were carried out on eight patients with various immunological disorders who were receiving plasma exchange with albumin solutions known to be contaminated with aluminium. Four patients with impaired renal function (creatinine clearance less than 50 ml/min) retained between 60% and 74% of the aluminium infused during a single plasma exchange. Transiliac bone biopsy specimens from three patients in this group had a high content of aluminium and showed histological evidence of current or previous bone disease related to aluminium. Two of these patients suffered intermittent bone pain. The main route of excretion of injected aluminium was in urine, only a small proportion of the total input being removed in the "plasma bag" during plasma exchange. The extent of aluminium retention and bone deposition was not reflected by the plasma aluminium concentration before or after plasma exchange. Treatment of five patients with intravenous desferrioxamine increased the plasma aluminium concentration and urinary output of aluminium in those with evidence of aluminium retention. These studies show that patients with poor renal function receiving treatment with albumin contaminated with aluminium retain the metal and deposit it in bone, where it may eventually cause aluminium bone disease. Plasma exchange should be used with caution in patients with renal impairment. 相似文献
12.
The haplotype distribution of the ΔF508 mutation in cystic fibrosis families in Scotland 总被引:1,自引:0,他引:1
Iain McIntosh Ann Curtis Maria-Luz Lorenzo Marion Keston Annette J. Gilfillan Gillian Morris David J. H. Brock 《Human genetics》1990,85(4):419-420
Summary The gene defective in cystic fibrosis (CF) has recently been isolated and the major mutation identified. The haplotype distribution
of this mutation (ΔF508) has been determined for 215 CF chromosomes in the Scottish population. ΔF508 represents 73% of all
CF mutations in this group. There remains considerable linkage disequilibrium between XV2c and KM19 and other mutations in
the CF gene. 相似文献
13.
Mapping of genes on the linear chromosome of the bacterium Borrelia burgdorferi: Possible locations for its origin of replication 总被引:13,自引:0,他引:13
Iain G. Old Jane MacDougall Isabelle Saint Girons Barrie E. Davidson 《FEMS microbiology letters》1992,99(2-3):245-250
Molecular clones of Borrelia burgdorferi, aetiologic agent of Lyme borreliosis, were isolated and analysed by DNA sequence determination. This procedure yielded B. burgdorferi homologues of gidA, gyrB, gyrA, ftsA and ftsZ. The genes were located on the physical map of the B. burgdorferi linear chromosome. Also mapped were the genes fla and p60 while dnaA was mapped using a heterologous probe. gyrA and gyrB were found to be in tandem and were mapped, along with dnaA at the centre of the chromosome. gidA was located close to the left hand extremity of the chromosome. Because gyrB, dnaA and gidA are normally located within 50 kb of the origin of replication (oriC), we propose two possible sites for oriC in the B. burgdorferi linear chromosome. 相似文献
14.
Determination of plasma [18F]-6-fluorodopa during positron emission tomography: elimination and metabolism in carbidopa treated subjects 总被引:1,自引:0,他引:1
An investigation of the metabolism of [18F]-6-fluorodopa (FDOPA) given to carbidopa treated subjects for scanning by positron emission tomography (PET) has been carried out by analysis of plasma. Reverse phase ion pair HPLC and alumina extraction were employed to fractionate and identify the [18F]-labelled compounds of plasma over a two hour period. During this time, the plasma levels of both total 18F and FDOPA decreased as a bi-exponential function of time. The rates of 18F, but not FDOPA, elimination were observed to decrease with age. In addition to FDOPA, only one other major peak of radioactivity was resolved by HPLC. Identification of this compound as the O-methylated derivative of FDOPA (MeFDOPA) is based on its shared HPLC elution time with in vitro synthesized O-[methyl-14C]-FDOPA. The ratio of the concentration of MeFDOPA to FDOPA (MeFDOPA/FDOPA) in plasma increased linearly with time, and the slope of this linear relationship decreased with the age of the individual. 相似文献
15.
For the recovery of intracellular material from bacteria it is often necessary to disrupt the cells. Much work has been done on the kinetics of protein release in beadmills,(1) homogenizers,(2) and by ultrasonication.(3) In this paper we report how the growth phase of Bacillus amyloliquefaciens grown in batch culture affects the rate of protein release by ball milling, ultrasonication, and autolysis. We further suggest that autolysis is a feasible method for disrupting Bacillus. 相似文献
16.
Production of bulblets of Muscari armeniacum through tissue culture is enhanced when 1 g/l activated charcoal is added to a modified Murashige and Skoog (MS) medium. Bulblet regeneration is direct from bulb scale explants with no intermediate callus growth. Bulblets can be transferred successfully to a greenhouse environment directly from aseptic culture. 相似文献
17.
18.
19.
Continuous transpiration and β-guage measurements were made on cotton plants, the stomatal apertures of which had been induced to oscillate, thus allowing a water balance to be made, and leaf potential to be measured as functions of time. 相似文献
20.