全文获取类型
收费全文 | 42594篇 |
免费 | 3136篇 |
国内免费 | 7篇 |
专业分类
45737篇 |
出版年
2023年 | 287篇 |
2022年 | 516篇 |
2021年 | 985篇 |
2020年 | 679篇 |
2019年 | 787篇 |
2018年 | 1498篇 |
2017年 | 1268篇 |
2016年 | 1551篇 |
2015年 | 2140篇 |
2014年 | 2243篇 |
2013年 | 2901篇 |
2012年 | 3473篇 |
2011年 | 3258篇 |
2010年 | 2015篇 |
2009年 | 1807篇 |
2008年 | 2385篇 |
2007年 | 2285篇 |
2006年 | 2201篇 |
2005年 | 1904篇 |
2004年 | 1844篇 |
2003年 | 1606篇 |
2002年 | 1438篇 |
2001年 | 685篇 |
2000年 | 571篇 |
1999年 | 548篇 |
1998年 | 397篇 |
1997年 | 291篇 |
1996年 | 302篇 |
1995年 | 255篇 |
1994年 | 218篇 |
1993年 | 200篇 |
1992年 | 265篇 |
1991年 | 267篇 |
1990年 | 208篇 |
1989年 | 207篇 |
1988年 | 177篇 |
1987年 | 154篇 |
1986年 | 151篇 |
1985年 | 167篇 |
1984年 | 126篇 |
1983年 | 94篇 |
1982年 | 82篇 |
1981年 | 93篇 |
1980年 | 90篇 |
1979年 | 108篇 |
1978年 | 99篇 |
1977年 | 77篇 |
1976年 | 72篇 |
1975年 | 69篇 |
1973年 | 66篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
192.
193.
Armand J. de Ricqlès 《Comptes Rendus Palevol》2011,10(5-6):509-515
Vertebrate palaeohistology has been considered for a long time as a modest subdivision of Palaeontology. Starting in the 1930s and 1940s, comparative bone tissue histology and palaeohistology progressively demonstrated the multiple correlations between bone tissue distribution and numerous biological variables, such as ontogenetic origin, growth, size, shape, biomechanics, physiology, and ecology. During the last three decades, Palaeohistology has focussed on deciphering the numerous, complex causes explaining the patterns and processes of Vertebrate evolution. Palaeohistology is a powerful tool, in connection with Biology, for the reconstruction of fossil Vertebrates as living organisms. 相似文献
194.
195.
196.
Nalini Santanam MingQing Song Rong Rong Ana A. Murphy Sampath Parthasarathy 《Free radical research》2013,47(12):1315-1321
Endometriosis affects younger women of childbearing age. Atherosclerosis is considered as a disease of the old and increases with the ageing process. Both diseases are characterized by the increased presence of activated macrophages and associated increases in growth promoting activity and the production of inflammatory cytokines. In this review, we propose that oxidative stress and the presence of forms of oxidized low-density lipoprotein (LDL) might contribute to both Atherosclerosis and Endometriosis. 相似文献
197.
Luís Roque Noélia Duarte Maria Rosário Bronze Catarina Garcia Julia Alopaeus Jesus Molpeceres 《Biofouling》2013,29(8):880-892
AbstractGlycyrrhiza glabra L. is considered an important source of bioactive compounds. This study aimed at the development of an efficient solution for the treatment of oral candidiasis. Several extracts of Glycyrrhiza glabra L. were prepared using different solvents and their potential in vitro antifungal activity was assessed. Ethanolic extracts showed the most promising results against C. albicans. This extract was incorporated into mucoadhesive nanoparticles (PLA, PLGA and alginate), which were further included in an oral gel, an oral film and a toothpaste, respectively. The results showed that nanoparticles were successfully produced, presenting a mean size among 100–900?nm with high encapsulation efficiency. In vitro studies showed that the most bioadhesive formulation was the oral film with extract-loaded PLGA nanoparticles, followed by the toothpaste with extract-loaded alginate nanoparticles and the oral gel with extract-loaded PLA nanoparticles. 相似文献
198.
199.
Increasing number of publications shows that cannabinoid receptor 1 (CB(1)) specific compounds might act in a CB(1) independent manner, including rimonabant, a potent CB(1) receptor antagonist. Opioids, cannabinoids and their receptors are well known for their overlapping pharmacological properties. We have previously reported a prominent decrease in μ-opioid receptor (MOR) activity when animals were acutely treated with the putative endocannabinoid noladin ether (NE). In this study, we clarified whether the decreased MOR activation caused by NE could be reversed by rimonabant in CB(1) receptor deficient mice. In functional [(35)S]GTPγS binding assays, we have elucidated that 0.1mg/kg of intraperitoneal (i.p.) rimonabant treatment prior to that of NE treatment caused further attenuation on the maximal stimulation of Tyr-d-Ala-Gly-(NMe)Phe-Gly-ol (DAMGO), which is a highly specific MOR agonist. Similar inhibitory effects were observed when rimonabant was injected i.p. alone and when it was directly applied to forebrain membranes. These findings are cannabinoid receptor independent as rimonabant caused inhibition in both CB(1) single knockout and CB(1)/CB(2) double knockout mice. In radioligand competition binding assays we highlighted that rimonabant fails to displace effectively [(3)H]DAMGO from MOR in low concentrations and is highly unspecific on the receptor at high concentrations in CB(1) knockout forebrain and in their wild-type controls. Surprisingly, docking computational studies showed a favorable binding position of rimonabant to the inactive conformational state of MOR, indicating that rimonabant might behave as an antagonist at MOR. These findings were confirmed by radioligand competition binding assays in Chinese hamster ovary cells stably transfected with MOR, where a higher affinity binding site was measured in the displacement of the tritiated opioid receptor antagonist naloxone. However, based on our in vivo data we suggest that other, yet unidentified mechanisms are additionally involved in the observed effects. 相似文献
200.
Rômulo Sátiro De Medeiros Ana Maria Camêlo Da Silva Francisco De Sousa Ramalho José Eduardo Serrão Paulo Roberto Cecon 《Biocontrol Science and Technology》2004,14(5):487-498
The daily reproductive rate of Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) fed with Alabama argillacea (Hübner) (Lepidoptera: Noctuidae) larvae was studied at constant temperatures of 20, 23, 25, 28, 30 and 33±0.2°C, relative humidity of 60±10% and photoperiod of L:D 14:10. Daily reproductive rate of P. nigripinus was affected by age of this predator. Each P. nigrispinus female laid 5.3 (20°C) to 19.9 eggs/day (28°C) which developed into 4.3–16.5 nymphs, respectively. Highest daily reproductive rate of P. nigrispinus was recorded at 28 and 30°C for 5–30-day-old females. This predator showed higher daily reproductive rate than its prey A. argillacea at 25°C. It was also able to reproduce at temperatures from 20 to 33°C with maximum daily reproductive rate between 25 and 30°C. These results are important for optimizing mass rearing of P. nigrispinus in the laboratory. 相似文献