全文获取类型
收费全文 | 808篇 |
免费 | 56篇 |
国内免费 | 1篇 |
出版年
2022年 | 3篇 |
2021年 | 7篇 |
2019年 | 6篇 |
2018年 | 8篇 |
2017年 | 4篇 |
2016年 | 13篇 |
2015年 | 28篇 |
2014年 | 48篇 |
2013年 | 46篇 |
2012年 | 60篇 |
2011年 | 53篇 |
2010年 | 35篇 |
2009年 | 31篇 |
2008年 | 48篇 |
2007年 | 63篇 |
2006年 | 52篇 |
2005年 | 39篇 |
2004年 | 48篇 |
2003年 | 49篇 |
2002年 | 31篇 |
2001年 | 18篇 |
2000年 | 10篇 |
1999年 | 6篇 |
1998年 | 11篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 9篇 |
1992年 | 4篇 |
1991年 | 7篇 |
1990年 | 13篇 |
1989年 | 5篇 |
1988年 | 9篇 |
1987年 | 4篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1972年 | 9篇 |
1971年 | 4篇 |
1969年 | 2篇 |
1967年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有865条查询结果,搜索用时 171 毫秒
1.
The computer program HYLAS generates from a standard DNA lettersequence a three-dimensional space curve (H curve) which embodiesthe entire information content of the original nucleotide sequence.The program can display H curves either as two-dimensional (frontand side view) projections or as stereo-pair images. The curvescan be marked at specific nucleotide locations, annotated, rotatedfor observation from any viewing angle, and manipulated forconvenient side-by-side comparisons. Unlike the cumbersome lettersequences, H curves can be drastically condensed in size withoutlosing their ability to reflect the global nucleotide-distributionpattern of the entire DNA sequence. Often, biologically importantloci can be visually identified on the H curves. HYLAS is writtenin FORTRAN with separate mainframe (IBM- VM/CMS) and microcomputer(MS-DOS) versions. It uses the Tektronix-TCS library of graphicsubroutines.
Received on October 24, 1988; accepted on July 15, 1989 相似文献
2.
Jaclyn S. Long Yuko Fujiwara Joanne Edwards Claire L. Tannahill Gabor Tigyi Susan Pyne Nigel J. Pyne 《The Journal of biological chemistry》2010,285(46):35957-35966
We demonstrate here that the bioactive lipid sphingosine 1-phosphate (S1P) uses sphingosine 1-phosphate receptor 4 (S1P4) and human epidermal growth factor receptor 2 (HER2) to stimulate the extracellular signal regulated protein kinase 1/2 (ERK-1/2) pathway in MDA-MB-453 cells. This was based on several lines of evidence. First, the S1P stimulation of ERK-1/2 was abolished by JTE013, which we show here is an S1P2/4 antagonist and reduced by siRNA knockdown of S1P4. Second, the S1P-stimulated activation of ERK-1/2 was almost completely abolished by a HER2 inhibitor (ErbB2 inhibitor II) and reduced by siRNA knockdown of HER2 expression. Third, phyto-S1P, which is an S1P4 agonist, stimulated ERK-1/2 activation in an S1P4- and HER2-dependent manner. Fourth, FTY720 phosphate, which is an agonist at S1P1,3,4,5 but not S1P2 stimulated activation of ERK-1/2. Fifth, S1P stimulated the tyrosine phosphorylation of HER2, which was reduced by JTE013. HER2 which is an orphan receptor tyrosine kinase is the preferred dimerization partner of the EGF receptor. However, EGF-stimulated activation of ERK-1/2 was not affected by siRNA knockdown of HER2 or by ErbB2 (epidermal growth factor receptor 2 (or HER2)) inhibitor II in MDA-MB-453 cells. Moreover, S1P-stimulated activation of ERK-1/2 does not require an EGF receptor. Thus, S1P and EGF function in a mutually exclusive manner. In conclusion, the magnitude of the signaling gain on the ERK-1/2 pathway produced in response to S1P can be increased by HER2 in MDA-MB-453 cells. The linkage of S1P with an oncogene suggests that S1P and specifically S1P4 may have an important role in breast cancer progression. 相似文献
3.
George L. Gabor Miklos 《Molecular & general genetics : MGG》1972,115(4):289-293
Summary This report shows that certain Minutes can greatly increase the frequency of sex chromosome non-disjunction in the In(1) sc
4L
sc
8R, 5E
y/y
+Y system in the Drosophila melanogaster male. This effect is evaluated and discussed with special reference to the recent finding that the Minutes may be deficiencies of transfer RNA loci. 相似文献
4.
A new algorithm is proposed to determine the type-II restrictionendonucleases' recognition site knowing the digested DNA sequenceand fragment lengths in an actual case. The algorithm is implementedfor the Commodore 64 microcomputer.
Received on January 6, 1987; accepted on June 19, 1987 相似文献
5.
Few studies have examined the role hormones play in mediating clinical changes associated with infection by the parasite Batrachochytrium dendrobatidis (Bd). Glucocorticoid (GC) hormones such as corticosteroids (CORT) regulate homeostasis and likely play a key role in response to infection in amphibians. We explore the relationship between CORT release rates and Bd infection in tadpoles of the common midwife toad, Alytes obstetricians, using a non-invasive water-borne hormone collection method across seven populations. We further examined whether tadpoles of A. muletensis infected with a hypervirulent lineage of Bd, BdGPL, had greater CORT release rates than those infected with a hypovirulent lineage, BdCAPE. Finally, we examined the relationship between righting reflex and CORT release rates in infected metamorphic toads of A. obstetricans. We found an interaction between elevation and Bd infection status confirming that altitude is associated with the overall severity of infection. In tandem, increasing elevation was associated with increasing CORT release rates. Tadpoles infected with the hypervirulent BdGPL had significantly higher CORT release rates than tadpoles infected with BdCAPE showing that more aggressive infections lead to increased CORT release rates. Infected metamorphs with higher CORT levels had an impaired righting reflex, our defined experimental endpoint. These results provide evidence that CORT is associated with an amphibian’s vulnerability to Bd infection, and that CORT is also affected by the aggressiveness of infection by Bd. Together these results indicate that CORT is a viable biomarker of amphibian stress. 相似文献
6.
7.
8.
9.
Nóra Kutszegi ágnes F. Semsei András Gézsi Judit C. Sági Viktória Nagy Katalin Csordás Zsuzsanna Jakab Orsolya Lautner-Csorba Krisztina Míta Gábor Gábor T. Kovács Dániel J. Erdélyi Csaba Szalai 《PloS one》2015,10(10)
L-asparaginase (ASP) is a key element in the treatment of paediatric acute lymphoblastic leukaemia (ALL). However, hypersensitivity reactions (HSRs) to ASP are major challenges in paediatric patients. Our aim was to investigate genetic variants that may influence the risk to Escherichia coli-derived ASP hypersensitivity. Sample and clinical data collection was carried out from 576 paediatric ALL patients who were treated according to protocols from the Berlin—Frankfurt—Münster Study Group. A total of 20 single nucleotide polymorphisms (SNPs) in GRIA1 and GALNT10 genes were genotyped. Patients with GRIA1 rs4958351 AA/AG genotype showed significantly reduced risk to ASP hypersensitivity compared to patients with GG genotype in the T-cell ALL subgroup (OR = 0.05 (0.01–0.26); p = 4.70E-04), while no such association was found in pre-B-cell ALL. In the medium risk group two SNPs of GRIA1 (rs2055083 and rs707176) were associated significantly with the occurrence of ASP hypersensitivity (OR = 0.21 (0.09–0.53); p = 8.48E-04 and OR = 3.02 (1.36–6.73); p = 6.76E-03, respectively). Evaluating the genders separately, however, the association of rs707176 with ASP HSRs was confined only to females. Our results suggest that genetic variants of GRIA1 might influence the risk to ASP hypersensitivity, but subgroups of patients can differ significantly in this respect. 相似文献
10.
Miklos Szucs Peter Osvath Attila Jakab Daniel Varga Balazs Varga Bela Juhasz 《Reproductive biology》2019,19(1):38-44
The relationship between overweight and male fertility is well studied, still the correlation of obesity and decreased sperm quality is a subject to debate. The widely used conventional spermatological examinations alone seem to be inadequate to assess fertilization potential. Hyaluronan Binding Assay (HBA®) is one of the available validated tests that allows the functional examination of sperm. Data of 72 male patients (mean age 33.9 (24–43) years) from infertile couples were analysed. Body Mass Index (BMI) determination, conventional semen analysis and HBA were performed. Additionally, a relatively new Hyaluronan Bound Matured Sperm Count (HB-MaSC) -index, first introduced by the authors in 2015, was calculated. This index reflects fertilization potential of sperm more precisely. With the increase of BMI, sperm count decreased significantly until about 25?kg/m2, above 25?kg/m2 no further decrease was observed, although sperm count remained permanently low. Greater body weight (in the 70–90?kg range) was observed to have a significant negative effect only on the progressive sperm motility. In addition to sperm concentration and motility, sperm fertilization potential is also negatively affected by obesity, but is irrespective of body weight, as evaluated using BMI + HB-MaSC linear regression analyses adjusted for age and weight. This correlation between male BMI and sperm fertilization potential – as opposed to the conventional correlations with sperm concentration or motility – appears to provide more helpful information in the identification of real capability for fertilization. 相似文献