全文获取类型
收费全文 | 3932篇 |
免费 | 347篇 |
国内免费 | 32篇 |
出版年
2023年 | 18篇 |
2022年 | 27篇 |
2021年 | 99篇 |
2020年 | 55篇 |
2019年 | 75篇 |
2018年 | 99篇 |
2017年 | 68篇 |
2016年 | 145篇 |
2015年 | 211篇 |
2014年 | 240篇 |
2013年 | 278篇 |
2012年 | 362篇 |
2011年 | 338篇 |
2010年 | 212篇 |
2009年 | 182篇 |
2008年 | 224篇 |
2007年 | 246篇 |
2006年 | 199篇 |
2005年 | 194篇 |
2004年 | 152篇 |
2003年 | 145篇 |
2002年 | 143篇 |
2001年 | 43篇 |
2000年 | 24篇 |
1999年 | 46篇 |
1998年 | 37篇 |
1997年 | 34篇 |
1996年 | 20篇 |
1995年 | 21篇 |
1994年 | 19篇 |
1993年 | 18篇 |
1992年 | 28篇 |
1991年 | 20篇 |
1990年 | 15篇 |
1989年 | 11篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 13篇 |
1985年 | 22篇 |
1984年 | 16篇 |
1983年 | 8篇 |
1982年 | 15篇 |
1981年 | 10篇 |
1980年 | 12篇 |
1979年 | 8篇 |
1977年 | 8篇 |
1975年 | 7篇 |
1974年 | 8篇 |
1969年 | 8篇 |
1967年 | 7篇 |
排序方式: 共有4311条查询结果,搜索用时 281 毫秒
1.
2.
3.
4.
5.
Elke Leng 《International journal of biometeorology》1978,22(3):190-196
Clinical evidence suggests that there may be some relationship between the occurrence of peptic ulcers and the season of the year. As little experimental work has been carried out on this subject, three drugs commonly used to induce experimental ulcers in rats (acetylsalicylic acid, 300 mg/kg; phenylbutazone, 200 mg/kg; reserpine, 10 mg/kg) were tested every month for one year under standardised experimental conditions (Ta, RH, LD 12:12). In rats given phenylbutazone the maximum area of ulceration was found in October and December, and in rats given acetylsalicylic acid in February and March. In rats given reserpine, there were no significant monthly variations. An influence of climatic factors on ulcer induction cannot be completely excluded. Endogenous conditions might also account for the monthly differences in ulceration. 相似文献
6.
zge Karayel Francesca Tonelli Sebastian Virreira Winter Phillip E. Geyer Ying Fan Esther M. Sammler Dario R. Alessi Martin Steger Matthias Mann 《Molecular & cellular proteomics : MCP》2020,19(9):1546-1560
Highlights
- •MS-based clinical assay that accurately determines phospho Rab10 occupancy.
- •Stable isotope labeled phosphopeptide injected as a standard with endogenous tryptic phospho Rab peptide for accurate ratio determination.
- •Determination of pRab levels in neutrophils of Parkinson disease patients.
- •Relevance of pRab levels as marker of PD.
7.
8.
Xiao Zhang Jinpeng Li Bo Yang Qina Leng Ji Li Xintuan Wang Junyao Lu Opeyemi Joshua Olatunji Jian Tang 《化学与生物多样性》2021,18(5):e2100065
This study investigated the protective effects of two polysaccharides (CPA-1 and CPB-2) from Cordyceps cicadae against high fructose/high fat diet (HF/HFD) induced obesity and metabolic disorders in rats. Rats were either fed with normal diet or HF/HFD and treated with CPA-1 and CPB-2 (100 and 300 mg/kg) for 11 weeks. Administration of CPA-1 and CPB-2 significantly and dose dependently reduced body and liver weight, insulin and glucose tolerance, serum insulin and glucose levels. Furthermore, serum and hepatic lipid profiles, liver function enzymes and proinflammatory cytokines (TNF-α, IL-1β and IL-6) were markedly reduced. Additionally, CPA-1 and CPB-2 treatment alleviated hepatic oxidative stress by reducing lipid peroxidation level (MDA) and upregulating glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase (CAT) activities as well as ameliorated histological alterations through the reduction of hepatic lipid accumulation. These results suggested that the polysaccharides from C. cicadae showed protective effects against HF/HFD induced metabolic disturbances and may be considered as a dietary supplement for treating obesity. 相似文献
9.
Food subsidies have the potential to modify ecosystems and affect the provision of goods and services. Predictable Anthropogenic Food Subsidies (PAFS) modify ecosystems by altering ecological processes and food webs. The global concern over the effects of PAFS in ecosystems has led to development of environmental policies aimed at curbing the production or ultimately banning of PAFS. However, the effects of reducing or banning PAFS are not known. We explore the consequences of PAFS removal in a marine ecosystem under two scenarios: 1) gradual reduction, or 2) an abrupt ban, using a mass balance model to test these hypotheses–The reduction or loss of PAFS will: i) modify trophic levels and food webs through effects on foraging by opportunistic species, ii) increase the resilience of opportunistic species to food shortages, and iii) modify predator–prey interactions through shifts in prey consumption. We found that PAFS lower the trophic levels of opportunistic scavengers and increase their food pathways. Scavengers are able to switch prey when PAFS are reduced gradually but they decline when PAFS are abruptly banned. PAFS reduction to a certain minimal level causes a drop in the ecosystem’s stability. We recommend gradual reduction of PAFS to a minimal level that would maintain the ecosystem’s stability and allow species exploiting PAFS to habituate to the food subsidy reduction. 相似文献
10.