全文获取类型
收费全文 | 97910篇 |
免费 | 9115篇 |
国内免费 | 41篇 |
出版年
2023年 | 331篇 |
2021年 | 1472篇 |
2020年 | 964篇 |
2019年 | 1267篇 |
2018年 | 1565篇 |
2017年 | 1428篇 |
2016年 | 2322篇 |
2015年 | 3974篇 |
2014年 | 4516篇 |
2013年 | 5392篇 |
2012年 | 7215篇 |
2011年 | 7020篇 |
2010年 | 4481篇 |
2009年 | 4213篇 |
2008年 | 5996篇 |
2007年 | 6024篇 |
2006年 | 5614篇 |
2005年 | 5444篇 |
2004年 | 5241篇 |
2003年 | 5028篇 |
2002年 | 4745篇 |
2001年 | 1072篇 |
2000年 | 852篇 |
1999年 | 1074篇 |
1998年 | 1273篇 |
1997年 | 858篇 |
1996年 | 785篇 |
1995年 | 811篇 |
1994年 | 693篇 |
1993年 | 771篇 |
1992年 | 734篇 |
1991年 | 639篇 |
1990年 | 654篇 |
1989年 | 637篇 |
1988年 | 581篇 |
1987年 | 553篇 |
1986年 | 504篇 |
1985年 | 693篇 |
1984年 | 748篇 |
1983年 | 668篇 |
1982年 | 763篇 |
1981年 | 700篇 |
1980年 | 688篇 |
1979年 | 444篇 |
1978年 | 515篇 |
1977年 | 441篇 |
1976年 | 444篇 |
1975年 | 358篇 |
1974年 | 392篇 |
1973年 | 399篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Summary Within many taxa the age of maturity is not simply positively correlated with the adult lifespan; the two variables are proportional to each other. The dimensionless number which is the constant of proportionality thus becomes something to be predicted by life history theory. 相似文献
32.
A. Tchirkov Jacques-Olivier Bay David Pernin Yves-Jean Bignon Pascale Rio Maria Grancho Fabrice Kwiatkowski Michel Giollant Paul Malet Pierre Verrelle 《Human genetics》1997,101(3):312-316
In ataxia-telangiectasia (A-T) patients, mutations in a single gene, ATM, result in an autosomal recessive syndrome that embraces a variety of clinical features and manifests extreme radiosensitivity
and a strong predisposition to malignancy. Heterozygotes for the ATM gene have no clinical expression of A-T but may be cancer prone with a moderate increase in in vitro radiosensitivity. We
performed a blind chromosomal analysis on G2-phase lymphocytes from 7 unrelated A-T patients, 13 obligate A-T heterozygotes (parents of the patients), and 14 normal controls
following X-irradiation with 1 Gy in order to evaluate this cytogenetic method as a tool for detection of ATM carriers. Both A-T homozygotes and heterozygotes showed significantly increased levels of radiation-induced chromatid damage
relative to that of normal controls. These results show that the G2-phase chromosomal radiosensitivity assay can be used for the detection of A-T heterozygotes. In combination with molecular
genetic analyses, this test may be of value in studies of familial and sporadic cancers aimed at determination of the potential
involvement of ATM mutations in tumor risk or development.
Received: 5 May 1997 / Accepted: 26 August 1997 相似文献
33.
34.
Sonia Tarazona Pedro Furió-Tarí David Turrà Antonio Di Pietro María José Nueda Alberto Ferrer Ana Conesa 《Nucleic acids research》2015,43(21):e140
As the use of RNA-seq has popularized, there is an increasing consciousness of the importance of experimental design, bias removal, accurate quantification and control of false positives for proper data analysis. We introduce the NOISeq R-package for quality control and analysis of count data. We show how the available diagnostic tools can be used to monitor quality issues, make pre-processing decisions and improve analysis. We demonstrate that the non-parametric NOISeqBIO efficiently controls false discoveries in experiments with biological replication and outperforms state-of-the-art methods. NOISeq is a comprehensive resource that meets current needs for robust data-aware analysis of RNA-seq differential expression. 相似文献
35.
36.
37.
38.
Xinzhu Deng David Michaelson Jason Tchieu Jin Cheng Diana Rothenstein Regina Feldman Sang-gyu Lee John Fuller Adriana Haimovitz-Friedman Lorenz Studer Simon Powell Zvi Fuks E. Jane Albert Hubbard Richard Kolesnick 《PloS one》2015,10(6)
Mammalian NOTCH1-4 receptors are all associated with human malignancy, although exact roles remain enigmatic. Here we employ glp-1(ar202), a temperature-sensitive gain-of-function C. elegans NOTCH mutant, to delineate NOTCH-driven tumor responses to radiotherapy. At ≤20°C, glp-1(ar202) is wild-type, whereas at 25°C it forms a germline stem cell⁄progenitor cell tumor reminiscent of human cancer. We identify a NOTCH tumor phenotype in which all tumor cells traffic rapidly to G2⁄M post-irradiation, attempt to repair DNA strand breaks exclusively via homology-driven repair, and when this fails die by mitotic death. Homology-driven repair inactivation is dramatically radiosensitizing. We show that these concepts translate directly to human cancer models. 相似文献
39.
The relation between hypertension and cognition in elders remains unclear, and studies on the effect of antihypertensive drugs on cognition have demonstrated conflicting results. This study was performed to evaluate if the association between hypertension and cognition in elders differed depending on serum concentrations of organochlorine (OC) pesticides, common neurotoxic chemicals. Participants were 644 elders aged 60–85 years who participated in the National Health and Nutrition Examination Survey 1999–2002 and were able to complete a cognitive test. We selected 6 OC pesticides that were commonly detected in the elderly. Cognition was assessed by the Digit Symbol Substitution Test (DSST), a relevant tool for evaluating hypertension-related cognitive function, and low cognition was defined by the DSST score < 25th percentile. When OC pesticides were not considered in the analyses, elders with hypertension had about 1.7 times higher risk of low cognition than those without hypertension. However, in analyses stratified by serum concentrations of OC pesticides, the associations between hypertension and low cognition were stronger the higher the serum concentrations of p,p’-DDT, p,p’-DDE, β-hexachlorocyclohexane, and trans-nonachlor increased. Among elders in the 3rd tertile of these pesticides, adjusted odds ratios were from 2.5 to 3.5. In contrast, hypertension was not clearly associated with the risk of low cognition in elders in the 1st tertile of these pesticides. Similar patterns were observed for the continuous DSST score dependent variable. The difference in the association between hypertension and DSST scores according to the levels of OC pesticides suggest a key role of OC pesticides in the development of hypertension-related cognitive impairment and may help to identify hypertensive elders who are at a high risk of cognitive impairment. 相似文献
40.