全文获取类型
收费全文 | 20193篇 |
免费 | 1055篇 |
国内免费 | 29篇 |
专业分类
21277篇 |
出版年
2023年 | 165篇 |
2022年 | 393篇 |
2021年 | 733篇 |
2020年 | 437篇 |
2019年 | 473篇 |
2018年 | 666篇 |
2017年 | 628篇 |
2016年 | 819篇 |
2015年 | 940篇 |
2014年 | 1198篇 |
2013年 | 1655篇 |
2012年 | 1743篇 |
2011年 | 1526篇 |
2010年 | 899篇 |
2009年 | 795篇 |
2008年 | 930篇 |
2007年 | 913篇 |
2006年 | 752篇 |
2005年 | 687篇 |
2004年 | 560篇 |
2003年 | 460篇 |
2002年 | 431篇 |
2001年 | 347篇 |
2000年 | 312篇 |
1999年 | 286篇 |
1998年 | 114篇 |
1997年 | 89篇 |
1996年 | 102篇 |
1995年 | 90篇 |
1994年 | 65篇 |
1993年 | 71篇 |
1992年 | 175篇 |
1991年 | 165篇 |
1990年 | 132篇 |
1989年 | 119篇 |
1988年 | 146篇 |
1987年 | 117篇 |
1986年 | 98篇 |
1985年 | 111篇 |
1984年 | 103篇 |
1983年 | 55篇 |
1982年 | 53篇 |
1981年 | 63篇 |
1980年 | 51篇 |
1979年 | 72篇 |
1978年 | 48篇 |
1977年 | 56篇 |
1976年 | 45篇 |
1974年 | 43篇 |
1973年 | 39篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Beneficial effects of n-hexane bark extract of Onosma echioides L. on diabetic peripheral neuropathy
Ambreen Shoaib Badruddeen Rakesh Kumar Dixit Magdah Ganash George Barreto Ghulam Md Ashraf Hefazat Hussain Siddiqui 《Journal of cellular biochemistry》2019,120(10):16524-16532
Onosma echioides Linn (Boraginaceae) is the most frequently used curative herb widely used for kidney obstruction, sciatic pain, and gout. The present study was designed to investigate the therapeutic effects of n-hexane bark extract of O. echioides (OE) L. root in vivo against Streptozotocin-induced diabetic neuropathy in SD rats. For in vivo activity, the experiment was categorized into five different groups (n = 5). Group-I was considered as nondiabetic/normal control (NC) treated with 0.5% carboxymethyl cellulose (CMC), Group II as diabetic control, Group-III, IV, and V served as diabetic treated with OE 50, OE 100, and pregabalin at a dose of 50, 100, and 10 mg/kg body weight, orally, respectively. Body weight, blood glucose, oral glucose tolerance test, behavioral studies (motor coordination test, thermal hyperalgesia, cold allodynia, locomotor activity, oxidative biomarkers (thio barbituric acid reactive substances [TBARS], superoxide dismutase [SOD], glutathione [GSH], and catalase), and histopathology of the sciatic nerve were performed. Treatment with OE showed a dose-dependent increase in neuroprotective activity by improving the myelination and decreasing the axonal swelling of nerve fibers. The verdicts of behavioral activities showed a remarkable effect on animals after the treatment of extract and standard drug pregabalin. In conclusion, our findings supported the traditional application of OE and explored its importance in the management of diabetic neuropathy. Additional clinical experiments may provide novel therapeutic drugs for diabetes and its complications. 相似文献
33.
34.
35.
36.
The rat major histocompatibility complex class I antigens RT1.Au and RT1.Eu from the u haplotype and RT1.An from the n haplotype were labeled with 14C-asparagine or with 3H-fucose, mannose, galactose, and N-acetylglucosamine. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed complete removal of radioactivity from the sugar-labeled antigen heavy chains by digestion with glycopeptidase F, an enzyme that removes N-linked glycans completely. High performance liquid chromatography analysis of the tryptic digests of the mixed sugar-labeled and asparagine-labeled antigens demonstrated that all the sugar-labeled peptides were coincident with asparagine-labeled peptides. The An antigen showed three glycopeptides, each of which had different amounts of sugar radioactivity. The antigens Au and Eu showed two glycopeptides with different amounts of radioactivity but at identical positions in the two antigens. Antigen Eu had an additional glycopeptide with a lower amount of radioactivity. The positions of the glycopeptides from the Au and Eu antigens were different from those of the An antigen. The peptide profiles of the 14C-asparagine-labeled Au and Eu antigens demonstrated distinct differences between the molecules. The results of this study show that: (a) all the glycans on rat class I antigens are N-linked, as they are on H-2 and HLA class I antigens; (b) there are compositional differences among the glycans in each of the three antigens; (c) the glycosylation pattern of the rat class I antigens is similar to that of the mouse class I antigens, which contain two or three glycans, in contrast to that of the human class I antigens, which contain only one glycan; and (d) the antigens Au and Eu from the same haplotype are more closely related to each other than they are to the An antigen. 相似文献
37.
38.
Dipak Kumar Banerjee 《Journal of biosciences》1987,11(1-4):311-319
Radio-labelled amphomycin (3H-amphomycin) forms a complex with dolichylmonophosphate in presence of Ca2+. Complex formation has also been documented with retinylmonophosphate and perhydromonoeneretinylmonophosphate. Analysis of
the space-filling model suggested both fatty acylated aspartic acid residue at the N-terminus of the lipopeptide and phosphate
head group of dolichylmonophosphate are necessary for the complex formation. The binding ability of amphomycin is then utilized
to localize dolichylmonophosphate in the microsomal membrane. Studies with microsomal membranes from hen oviduct suggested
that dolichylmonophosphate is located in the cytoplasmic side of the membrane. 相似文献
39.
S. K. Podder A. Chakraborti K. Vijayalakshmi P. Lalit Kumar Singh 《Journal of biosciences》1987,11(1-4):495-502
To examine how surface Potential controls the reactivity of glycoconjugates at cell surface, the interaction of galactose-sPecific
lectinse.g. peanut agglutinin,Ricinus cummunis agglutinin with liPosomes bearing asialo GM1 were studied in the Presence of varying amount of ganglioside mixture, GMn. The Presence of 5% GMn causes comPlete slowing down of PreciPitin reaction and thereby make carbohydrate moiety of asialo GM1 comPletely inaccessiblei.e. ‘cryPtic’. In contrast the Presence of 1–2% GMn enhances the aPParent rate and amPlitude of the PreciPitin reaction as surface Potential becomes more negative. The relevance
of the findings has been discussed in relation to the exPression and involvement of the cell-surface sialic acid residues
during develoPment and differentiation. 相似文献
40.
The phylogenetic relationships among three derivative forms of the immigrans-Hirtodrosophila radiation viz. Chaetodrosophilella, Zaprionus and the immigrans species group are examined, by comparing the banding patterns of their polytene chromosomes and by analysing the nature of their heterochromatin. Based on the results of these studies it is concluded that D. quadrilineata has a very strong affinity with the members of the immigrans species group, while the genus Zaprionus represents a very distinct evolutionary lineage. This study further indicates that D. quadrilineata is a karyotypically primitive species having five pairs of rods and one pair of dots, while the karyotype of other members of the immigrans species group appears to have undergone modifications through fusions, fissions, inversions and the addition or deletion of heterochromatin to dots and other chromosomes. 相似文献