全文获取类型
收费全文 | 75735篇 |
免费 | 6994篇 |
国内免费 | 2227篇 |
出版年
2022年 | 496篇 |
2021年 | 1626篇 |
2020年 | 1232篇 |
2019年 | 1455篇 |
2018年 | 1644篇 |
2017年 | 1347篇 |
2016年 | 1874篇 |
2015年 | 2525篇 |
2014年 | 3038篇 |
2013年 | 3370篇 |
2012年 | 4023篇 |
2011年 | 3681篇 |
2010年 | 2409篇 |
2009年 | 2170篇 |
2008年 | 2924篇 |
2007年 | 2680篇 |
2006年 | 2516篇 |
2005年 | 2187篇 |
2004年 | 1978篇 |
2003年 | 1794篇 |
2002年 | 1692篇 |
2001年 | 4064篇 |
2000年 | 3582篇 |
1999年 | 2773篇 |
1998年 | 1008篇 |
1997年 | 923篇 |
1996年 | 842篇 |
1995年 | 738篇 |
1994年 | 771篇 |
1993年 | 586篇 |
1992年 | 1797篇 |
1991年 | 1588篇 |
1990年 | 1497篇 |
1989年 | 1339篇 |
1988年 | 1180篇 |
1987年 | 1108篇 |
1986年 | 972篇 |
1985年 | 940篇 |
1984年 | 666篇 |
1983年 | 612篇 |
1979年 | 692篇 |
1978年 | 495篇 |
1975年 | 544篇 |
1974年 | 609篇 |
1973年 | 609篇 |
1972年 | 626篇 |
1971年 | 602篇 |
1970年 | 561篇 |
1969年 | 564篇 |
1968年 | 453篇 |
排序方式: 共有10000条查询结果,搜索用时 44 毫秒
1.
Single Cell Transcriptome Amplification with MALBAC 总被引:1,自引:0,他引:1
2.
3.
One new genus of the spider subfamily Coelotinae, Flexicoelotes
gen. n., with five new species is described from southern China: Flexicoelotes
huyunensis
sp. n. (female), Flexicoelotes
jiaohanyanensis
sp. n. (male and female), Flexicoelotes
jinlongyanensis
sp. n. (male and female), Flexicoelotes
pingzhaiensis
sp. n. (female), Flexicoelotes
xingwangensis
sp. n. (male and female). 相似文献
4.
A. A. Minervina A. Y. Komkov I. Z. Mamedov Y. B. Lebedev 《Doklady. Biochemistry and biophysics》2016,467(1):85-88
T cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignant neoplasm of the lymphocyte precursors that suffered malignant transformation arresting the lymphoid cell differentiation. Clinical studies revealed monoor, more rarely, oligoclonal nature of the disease. A precise identification of malignant clone markers is both the crucial stage of early diagnostics and the essential prognostic factor for therapeutic treatment. Here we present an improved system for unbiased detection of lymphoblastic clones in bone marrow aspirates of T-ALL patients. The system based on multiplex PCR of rearranged T-cell receptor locus (TRB) and straightforward sequencing of the resulted PCR fragments. Testing of the system on genomic DNA from Jurkat cell line and four clinical bone marrow aspirates revealed a set of unique TRB rearrangements that precisely characterize each of tested samples. Therefore, the outcome of the system produces highly informative molecular genetic markers for further monitoring of minimal residual disease in T-ALL patients. 相似文献
5.
6.
7.
8.
U Z Muratova V T Bornikov A Kh Abdukaiumova T S Saatov 《Biokhimii?a (Moscow, Russia)》1991,56(2):320-325
The activity of phospholipase A2 in blood platelets of healthy donors and IHD patients was examined. The enzyme activity was found to be increased 3-fold in platelets possessing a high level of functional activity (IHD) and by one order of magnitude in patients with myocardial infarction as compared with healthy donors. An enzyme preparation possessing a phospholipase activity was isolated from platelets by using salt extraction (KCl) and sonication. Purification of the enzyme by affinity chromatography resulted in two protein peaks both having a phospholipase A2 activity, the purification and molecular masses of these fractions being 768- and 2200-fold, and 13.5 and 15 kDa, respectively. It was supposed that these proteins are substrate-specific forms of phospholipase A2. 相似文献
9.
Three saponins from Oxytropis species. 总被引:2,自引:0,他引:2
Three flavonoids and three saponins have been isolated from Oxytropis species. Their structures were determined as isorhamnetin-3-O-beta-D-glucoside, rhamnetin-3-O-beta-D-galactoside, apigenin, 3-O-[alpha-L-rhamnopyranosyl (1----2)-beta-D-glucopyranosyl(1----4)-beta-D-glucuronopyranosyl]+ ++soyasapogenol B, 3-O-[beta-D-glucopyranosyl(1----2)-beta-D-glucuronopyranosyl] azukisapogenol and a new saponin 3-O-[beta-D-glucopyranosyl(1----2)-beta-D-glucopyranosyl]-25-O-alpha-L- rhamnopyranosyl-(20S,24S)-3 beta,16 beta, 20,24,25-pentahydroxy-9,19-cycloanostane. 相似文献
10.
W. D. Roof H. Q. Fang K. D. Young Jianling Sun & Ry Young 《Molecular microbiology》1997,25(6):1031-1046
slyD encodes a 196 amino acid polypeptide that is a member of the FKBP family of cis–trans peptidyl–prolyl isomerases (PPIases). slyD mutations affect plaque formation by the phage φX174 by blocking the action of the phage lysis protein E. Here we describe the selection of a set of spontaneous slyD mutations conferring resistance to the expression of gene E from a plasmid. These mutations occur disproportionately in residues of SlyD that, based on the structure of the prototype mammalian FKBP12, make ligand contacts with immunosuppressing drug molecules or are conserved in other FKBP proteins. A wide variation in the plating efficiency of φX174 on these E R strains is observed, relative to the parental, indicating that these alleles differ widely in residual SlyD activity. Moreover, it is found that slyD mutations cause significant growth rate defects in Escherichia coli B and C backgrounds. Finally, overexpression of slyD causes filamentation of the host. Thus, among the FKBP genes found in organisms across the evolutionary spectrum, slyD is unique in having three distinct drug-independent phenotypes. 相似文献