全文获取类型
收费全文 | 3332篇 |
免费 | 289篇 |
国内免费 | 4篇 |
专业分类
3625篇 |
出版年
2023年 | 13篇 |
2022年 | 39篇 |
2021年 | 50篇 |
2020年 | 40篇 |
2019年 | 54篇 |
2018年 | 44篇 |
2017年 | 52篇 |
2016年 | 77篇 |
2015年 | 125篇 |
2014年 | 159篇 |
2013年 | 171篇 |
2012年 | 239篇 |
2011年 | 298篇 |
2010年 | 178篇 |
2009年 | 140篇 |
2008年 | 198篇 |
2007年 | 230篇 |
2006年 | 179篇 |
2005年 | 188篇 |
2004年 | 165篇 |
2003年 | 162篇 |
2002年 | 156篇 |
2001年 | 37篇 |
2000年 | 17篇 |
1999年 | 39篇 |
1998年 | 37篇 |
1997年 | 26篇 |
1996年 | 23篇 |
1995年 | 22篇 |
1994年 | 23篇 |
1993年 | 35篇 |
1992年 | 14篇 |
1991年 | 25篇 |
1990年 | 21篇 |
1989年 | 14篇 |
1988年 | 24篇 |
1987年 | 19篇 |
1986年 | 19篇 |
1985年 | 23篇 |
1984年 | 23篇 |
1983年 | 19篇 |
1982年 | 19篇 |
1981年 | 29篇 |
1980年 | 20篇 |
1979年 | 15篇 |
1977年 | 18篇 |
1976年 | 13篇 |
1975年 | 11篇 |
1974年 | 16篇 |
1973年 | 13篇 |
排序方式: 共有3625条查询结果,搜索用时 15 毫秒
1.
Leslie A. Holladay Phillip Wilder 《Biochimica et Biophysica Acta (BBA)/General Subjects》1980,629(1):156-167
The effect of cationic, anionic and nonionic detergents on the EPR spectrum of spin-labeled somatostatin has been studied. At detergent concentrations well above the critical micelle concentration, nonionic detergents do not alter the EPR spectrum. Sodium dodecyl sulfate markedly alters both the line height ratio and the hyperfine splitting constant, whilst dodecyltrimethylammonium bromide alters only slightly the hyperfine splitting constant and line height ratio. The somatostatin-sodium dodecyl sulfate complex appeared monodisperse by sedimentation equilibrium with about 17 g bound detergent per g peptide. Circular dichroic and difference spectra of the dodecyl sulfate-somatostatin complex show that the tryptophanyl residue is buried in a nonpolar environment and that the secondary and tertiary structure of the peptide is markedly altered. Sedimentation equilibrium studies suggest that two types of dodecyltrimethylammonium-somatostatin complex exist. One type resembles the dodecyl sulfate-peptide complex, whilst the other appears to include several peptide units with only about one gram bound detergent per gram peptide. 相似文献
2.
Phillip A. Morin 《Conservation Genetics》2000,1(3):271-275
3.
Phillip A. Reece Margot Peikert 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1980,181(2):207-217
A reversed-phase, high-performance liquid chromatographic method employing fluorescence detection is described for the rapid quantification of plasma levels of quinidine, dihydroquinidine and 3-hydroxyquinidine. It involves protein precipitation with acetonitrile followed by direct injection of the supernatant into the chromatograph. For the preparation of plasma standards, pure 3-hydroxyquinidine was isolated from human urine by a simplified thin-layer chromatographic procedure. The mobile phase for the chromatography was a mixture of 1.5 mM aqueous phosphoric acid and acetonitrile (90:10) at a flow-rate of 2 ml/min. The intra-assay coefficient of variation for the assay of quinidine and 3-hydroxyquinidine over the concentration range 2.5–20 μmole/l was < 1% for both. Interassay coefficients of variation for quinidine (10 μmole/l) and 3-hydroxyquinidine (5 μmole/l) were 3.5% and 4.0% with detection limits of 50 and 25 μmole/l respectively. The method correlated well (r2 = 0.96) with an independently developed gas—liquid chromatographic—nitrogen detection assay for quinidine which also possessed a high degree of precision. (Intra-assay coefficient of variation 3.6% at 20 μmole/l). As expected, comparison of the high-performance liquid chromatographic assay with a published protein precipitation—fluorescence assay showed poor correlation (r2 = 0.78). 相似文献
4.
5.
Andrew W. Saxe Ji-Won Yoon Phillip Gorden Murray F. Brennan 《In vitro cellular & developmental biology. Plant》1982,18(10):884-890
Summary Dispersed cells from both fresh and cryopreserved human insulinoma have been maintained in cell culture. Initial yield of
viable cells was 50% for fresh and 25% for cryopreserved tissue. Viability of cells in culture was documented by increasing
numbers of cells (doubling time approximately 5 d initially and 2 d at the sixth subculture for both fresh and cryopreserved
tissue) and continued release of insulin over time (approximately 100 ng/ml per 105 cells at 10 d and 175 ng/ml per 105 cells at 30 d of culture for both fresh and cryopreserved tissue). Evidence that cells growing in culture were beta cells
was provided by: (a) recovery of intracellular and extracellular immunoreactive insulin (IRI), (b) electron microscopic morphology,
and (c) immunohistochemical staining. Cells from fresh insulinoma incubated with increasing concentrations of extracellular
glucose released increasing amounts of IRI up to approximately 15 mM glucose, which paralleled changes in plasma insulin obtained during a preoperative glucose tolerance test.
Under an Intergovernmental Personnel Act Exchange from the Department of Surgery, University of California, Davis, Sacramento
Medical Center. 相似文献
6.
7.
Phillip Cribb 《Curtis's Botanical Magazine》2005,22(1):22-24
Summary. The golden‐flowered Masdevallia niesseniae Luer from Colombia is described and illustrated from the type collection. 相似文献
8.
9.
10.
Studies of the toxicity of 2,4,5,6-tetrachloroisophthalonitrile (TCIN) to cells of Saccharomyces pastorianus and Neurospora crassa showed that 2 to 4 μg/ml of the toxicant were required to inhibit growth. Several thiol compounds reversed toxicity to growth. Glucose oxidation was severely impaired in treated cells of both test organisms. The toxicant at 2 or 4 μg/ml markedly reduced soluble thiol content of these cells. Bound thiol content was less affected in S. pastorianus cells than soluble thiol content. Uptake of toxicant by yeast cells was accompanied by formation of derivatives, some of which resembled those formed by reaction of glutathione with TCIN in vitro. Coenzyme A, glutathione, and 2-mercaptoethanol readily formed derivatives with TCIN in vitro. The nature of these derivatives was studied using 2-mercaptoethanol products as model substituents. Four derivatives were formed with 2-mercaptoethanol each with similar functional groups but showing dissimilar degrees of mobility during silica gel chromatography. Evidence indicated that these are derivatives of TCIN in which 1 to 4 of the halogens has been substituted by 2-mercaptoethanol. The mechanism of fungicidal action of TCIN is attributed to thiol inactivation. 相似文献