全文获取类型
收费全文 | 21324篇 |
免费 | 2296篇 |
国内免费 | 933篇 |
出版年
2023年 | 175篇 |
2022年 | 392篇 |
2021年 | 715篇 |
2020年 | 526篇 |
2019年 | 590篇 |
2018年 | 623篇 |
2017年 | 493篇 |
2016年 | 707篇 |
2015年 | 964篇 |
2014年 | 1193篇 |
2013年 | 1209篇 |
2012年 | 1485篇 |
2011年 | 1315篇 |
2010年 | 899篇 |
2009年 | 783篇 |
2008年 | 915篇 |
2007年 | 926篇 |
2006年 | 769篇 |
2005年 | 677篇 |
2004年 | 627篇 |
2003年 | 527篇 |
2002年 | 471篇 |
2001年 | 1294篇 |
2000年 | 1115篇 |
1999年 | 847篇 |
1998年 | 282篇 |
1997年 | 292篇 |
1996年 | 240篇 |
1995年 | 196篇 |
1994年 | 213篇 |
1993年 | 155篇 |
1992年 | 434篇 |
1991年 | 376篇 |
1990年 | 316篇 |
1989年 | 264篇 |
1988年 | 220篇 |
1987年 | 169篇 |
1986年 | 170篇 |
1985年 | 135篇 |
1984年 | 70篇 |
1983年 | 74篇 |
1982年 | 31篇 |
1979年 | 44篇 |
1978年 | 30篇 |
1976年 | 37篇 |
1975年 | 35篇 |
1973年 | 39篇 |
1972年 | 50篇 |
1971年 | 45篇 |
1970年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
D G Warnock W C Yang Z Q Huang E J Cragoe 《The Journal of biological chemistry》1988,263(15):7216-7221
Amiloride is a reversible inhibitor of the Na+/H+ antiporter which acts at the external aspect of the transport system. The kinetics of inhibition of the Na+/H+ antiporter with amiloride have been controversial, with the usual finding of simple competitive inhibition, but with other reports of mixed and noncompetitive inhibition of the transporter by amiloride. The present experiments demonstrate that the chloride content of the external transport buffer affects the kinetics of amiloride inhibition. Either simple competitive or mixed inhibition by amiloride was observed in the same vesicle preparations depending on the presence of chloride or gluconate in the buffer. The effect of chloride on the inhibitory effect of amiloride was dependent on the concentration of chloride and amiloride. Similar effects were observed with more potent analogues of amiloride. These findings suggest that the external aspect of the antiporter has a site or sites at which the inhibitory effects of amiloride on the Na+/H+ antiporter can be modified by chloride, even though chloride has only slight effects on the kinetics of the Na+/H+ antiporter in the absence of amiloride. 相似文献
32.
33.
34.
35.
Jin-Ying Cui Han Miao Li-Hong Ding Todd C. Wehner Pan-Na Liu Ye Wang Sheng-Ping Zhang Xing-Fang Gu 《PloS one》2016,11(2)
Spines or trichomes on the fruit of cucumbers enhance their commercial value in China. In addition, glabrous mutants exhibit resistance to aphids and therefore their use by growers can reduce pesticide residues. Previous studies have reported two glabrous mutant plants containing the genes, csgl1 and csgl2. In the present study, a new glabrous mutant, NCG157, was identified showing a gene interaction effect with csgl1 and csgl2. This mutant showed the glabrous character on stems, leaves, tendrils, receptacles and ovaries, and there were no spines or tumors on the fruit surface. Inheritance analysis showed that a single recessive gene, named csgl3, determined the glabrous trait. An F2 population derived from the cross of two inbred lines 9930 (a fresh market type from Northern China that exhibits trichomes) and NCG157 (an American processing type with glabrous surfaces) was used for genetic mapping of the csgl3 gene. By combining bulked segregant analysis (BAS) with molecular markers, 18 markers, including two simple sequence repeats (SSR), nine insertion deletions (InDel) and seven derived cleaved amplified polymorphism sequences (dCAPs), were identified to link to the csgl3 gene. All of the linked markers were used as anchor loci to locate the csgl3 gene on cucumber chromosome 6. The csgl3 gene was mapped between the dCAPs markers dCAPs-21 and dCAPs-19, at genetic distances of 0.05 cM and 0.15 cM, respectively. The physical distance of this region was 19.6 kb. Three markers, InDel-19, dCAPs-2 and dCAPs-11, co-segregated with csgl3. There were two candidate genes in the region, Csa6M514860 and Csa6M514870. Quantitative real-time PCR showed that the expression of Csa6M514870 was higher in the tissues of 9930 than that of NCG157, and this was consistent with their phenotypic characters. Csa6M514870 is therefore postulated to be the candidate gene for the development of trichomes in cucumber. This study will facilitate marker-assisted selection (MAS) of the smooth plant trait in cucumber breeding and provide for future cloning of csgl3. 相似文献
36.
The bioinorganic complexes of europium with N-acetyl-DL-alanine, N-acetyl-DL-valine, and DL-alanyl-DL-alanine have been synthesized and the M?ssbauer spectra at room temperature have been measured for these solid state complexes. The M?ssbauer parameters indicate that the water molecules in these complexes are not directly linked to the central europium ion and are outside the coordination sphere of europium and biological ligands, and that the chemical bond between the europium ion and the ligands may be predominantly ionic in character, with the possibility of partial covalent contribution. 相似文献
37.
Mohanty Madhumita Jena; Ye Maian; Li Xingli; Rossi Noreen F. 《American journal of physiology. Cell physiology》2001,281(2):C555
Hypotonicswelling increases the intracellular Ca2+ concentration([Ca2+]i) in vascular smooth muscle cells(VSMC). The source of this Ca2+ is not clear. To study thesource of increase in [Ca2+]i in response tohypotonic swelling, we measured [Ca2+]i infura 2-loaded cultured VSMC (A7r5 cells). Hypotonic swelling produced a40.7-nM increase in [Ca2+]i that was notinhibited by EGTA but was inhibited by 1 µM thapsigargin. Priordepletion of inositol 1,4,5-trisphosphate (IP3)-sensitive Ca2+ stores with vasopressin did not inhibit the increasein [Ca2+]i in response to hypotonic swelling.Exposure of 45Ca2+-loaded intracellular storesto hypotonic swelling in permeabilized VSMC produced an increase in45Ca2+ efflux, which was inhibited by 1 µMthapsigargin but not by 50 µg/ml heparin, 50 µM ruthenium red, or25 µM thio-NADP. Thus hypotonic swelling of VSMC causes a release ofCa2+ from the intracellular stores from a novel sitedistinct from the IP3-, ryanodine-, and nicotinic acidadenine dinucleotide phosphate-sensitive stores. 相似文献
38.
39.
Fetuses of 12 near-term sheep were prepared for microsphere determination of cerebral blood flow. Experiments were performed 5 days postsurgery. The regional blood flows were measured in successive high (HV), low (LV) and high voltage electrocorticographic states. Comparisons were made between the observations made in the LV and averaged flanking HV cycles. Total cerebral blood flow was 95 +/- 8, 119 +/- 11 and 100 +/- 9 ml/min/100 g in HV, LV and HV, respectively. Low voltage electrocortical activity increased average cerebral blood flow by 22% (P less than 0.01). Significant changes were seen in all regions except the occipital cortex. The maximum change was observed in the thalamus in which the flows were 152 +/- 23, 243 +/- 35 and 138 +/- 20 ml/min/per 100 g tissue, respectively. The increase was 68% (P less than 0.001). The percent changes seen in the cerebrum are as follows: Frontal grey + 18%, frontal white + 22%, parietal white + 22%, temporal + 18%. A + 17% change was seen in the cord (P less than 0.03). It is concluded that in low voltage electrocortical activity all of the brain, except the occipital region, shows an increase in cerebral blood flow. This is probably secondary to a variance in cerebral activity. This preparation may be useful in localizing function in the fetal brain. 相似文献
40.