全文获取类型
收费全文 | 1121篇 |
免费 | 79篇 |
专业分类
1200篇 |
出版年
2023年 | 7篇 |
2022年 | 11篇 |
2021年 | 18篇 |
2020年 | 12篇 |
2019年 | 18篇 |
2018年 | 19篇 |
2017年 | 19篇 |
2016年 | 37篇 |
2015年 | 62篇 |
2014年 | 43篇 |
2013年 | 62篇 |
2012年 | 81篇 |
2011年 | 85篇 |
2010年 | 40篇 |
2009年 | 54篇 |
2008年 | 55篇 |
2007年 | 64篇 |
2006年 | 43篇 |
2005年 | 38篇 |
2004年 | 63篇 |
2003年 | 38篇 |
2002年 | 43篇 |
2001年 | 17篇 |
2000年 | 13篇 |
1999年 | 13篇 |
1998年 | 9篇 |
1997年 | 11篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 8篇 |
1992年 | 21篇 |
1991年 | 16篇 |
1990年 | 11篇 |
1989年 | 19篇 |
1988年 | 21篇 |
1987年 | 9篇 |
1986年 | 12篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1983年 | 12篇 |
1981年 | 4篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1975年 | 6篇 |
1974年 | 3篇 |
1969年 | 4篇 |
1968年 | 3篇 |
1967年 | 2篇 |
1966年 | 3篇 |
排序方式: 共有1200条查询结果,搜索用时 15 毫秒
61.
Purkis Sam J. Gleason Arthur C. R. Purkis Charlotte R. Dempsey Alexandra C. Renaud Philip G. Faisal Mohamed Saul Steven Kerr Jeremy M. 《Coral reefs (Online)》2019,38(3):467-488
Coral Reefs - With compelling evidence that half the world’s coral reefs have been lost over the last four decades, there is urgent motivation to understand where reefs are located and their... 相似文献
62.
Franck X Fournet A Prina E Mahieux R Hocquemiller R Figadère B 《Bioorganic & medicinal chemistry letters》2004,14(14):3635-3638
Several quinolines were synthesized and evaluated in vitro against several parasites (Trypanosoma brucei, T. cruzi, Leishmania infantum, L. amazonensis, Plasmodium falciparum). Then, they were evaluated in vitro (at 10 microM), against HTLV-1 transformed cells. A few of them displayed interesting activities, comparable to the reference drugs. 相似文献
63.
64.
Goto Y Hogg JC Shih CH Ishii H Vincent R van Eeden SF 《American journal of physiology. Lung cellular and molecular physiology》2004,287(1):L79-L85
Exposure to air pollution [particulate matter, particles <10 microm (PM(10))] causes a systemic inflammatory response that includes stimulation of the bone marrow (BM) and progression of atherosclerosis. Monocytes are known to play a key role in atherogenesis by migration into subendothelial lesions where they appear as foam cells. The present study was designed to quantify the BM monocyte response in Watanabe heritable hyperlipidemic (WHHL) rabbits after PM(10) exposure. WHHL rabbits were given twice weekly intrapharyngeal instillations of 5 mg of PM(10) for 4 wk to a total of 40 mg and compared with control WHHL or New Zealand White (NZW) rabbits. The thymidine analog 5'-bromo-2'-deoxyuridine was used to label dividing cells in the BM and a monoclonal antibody to identify monocytes in peripheral blood. The transit time of monocytes through the BM was faster in WHHL than in NZW rabbits (30.4 +/- 1.9 h vs. 35.2 +/- 0.9 h, WHHL vs. NZW; P < 0.05). PM(10) instillation exposure increased circulating band cell counts, caused rapid release of monocytes from the BM, and further shortened their transit time through the BM to 23.2 +/- 1.6 h (P < 0.05). The percentage of alveolar macrophages containing particles in the lung correlated with the BM transit time of monocytes (r(2) = 0.45, P <0.05). We conclude that atherosclerosis increases the release of monocytes from the BM, and PM(10) exposure accelerates this process in relation to the amount of particles phagocytosed by alveolar macrophages. 相似文献
65.
Changes of action potentials and force at lowered [Na+]o in mouse skeletal muscle: implications for fatigue 总被引:2,自引:0,他引:2
Cairns SP Buller SJ Loiselle DS Renaud JM 《American journal of physiology. Cell physiology》2003,285(5):C1131-C1141
We examined 1) whether the effects of lowered trans-sarcolemmal Na+ gradient on force differed between nonfatigued fast- and slow-twitch muscles of mice and 2) whether effects on action potentials could explain the decrease of force. The Na+ gradient was reduced by lowering the extracellular [Na+] ([Na+]o). The peak force-[Na+]o relationships for the twitch and tetanus were the same in nonfatigued extensor digitorum longus and soleus muscles: force was maintained over a large range of [Na+]o and then decreased abruptly over a much smaller range. However, fatigue was significantly exacerbated at a lowered [Na+]o that had little effect in nonfatigued soleus muscle. This finding suggests that substantial differences exist in the Na+ effect on force between nonfatigued and fatigued muscle. The reduced contractility in nonfatigued muscles at lowered [Na+]o was largely due to 1) an increased number of inexcitable fibers and threshold for action potentials, 2) a reduction of action potential amplitude, and 3) a reduced capacity to generate action potentials throughout trains. sodium gradient; muscle contraction; action potential train; extensor digitorum longus; soleus 相似文献
66.
InlB, a surface-localized protein of Listeria monocytogenes, induces phagocytosis in non-phagocytic mammalian cells by activating Met, a receptor tyrosine kinase. InlB also binds glycosaminoglycans and the protein gC1q-R, two additional host ligands implicated in invasion. We present the structure of InlB, revealing a highly elongated molecule with leucine-rich repeats that bind Met at one end, and GW domains that dissociably bind the bacterial surface at the other. Surprisingly, the GW domains are seen to resemble SH3 domains. Despite this, GW domains are unlikely to act as functional mimics of SH3 domains since their potential proline-binding sites are blocked or destroyed. However, we do show that the GW domains, in addition to binding glycosaminoglycans, bind gC1q-R specifically, and that this binding requires release of InlB from the bacterial surface. Dissociable attachment to the bacterial surface via the GW domains may be responsible for restricting Met activation to a small, localized area of the host cell and for coupling InlB-induced host membrane dynamics with bacterial proximity during invasion. 相似文献
67.
Using a simplified model of the upper airways with two independent collapsible elements (nostrils and hypo-pharynx), we calculated the cross-sectional area of these two elements, taking into account pressure drops. We experimentally measured flow and pressure in the fossa and hypo-pharynx in various syndromes. This allowed us to compare the behaviour of the area supplied by our model with the aerodynamic resistance that is often used to analyse upper airway flow limitation events. We showed that nostril and hypo-pharyngeal areas are better correlated than the resistance values and thus concluded that the pressure divided by the square of the flow is a better parameter for analysing flow limitation in upper airways than resistance. Owing to its simplicity, our model is able to supply the area of the collapsible element in real time, which is impossible with more sophisticated models. 相似文献
68.
69.
Leboeuf B Guillouet P Batellier F Bernelas D Bonné JL Forgerit Y Renaud G Magistrini M 《Theriogenology》2003,60(5):867-877
The fertilization capacity of goat sperm stored in milk extenders is approximately 12-24h. Long-term storage of goat sperm (up to 3 days) is desirable as it would confer greater flexibility to breeding farms. The aim of this study was to evaluate in vitro motility parameters of buck spermatozoa for up to 7 days of storage using skim milk or chemically defined extender supplemented with native phosphocaseinate (NPPC). Four experiments were conducted to determine optimum temperature (4 or 15 degrees C) and storage conditions (aerobic versus anaerobic), the effect of seminal plasma on sperm survival, the optimal concentration of NPPC and the effect of beta lactoglobulin (BL). Both skim milk and NPPC were found to be more efficient for preserving goat sperm at 4 degrees C than at 15 degrees C (P<0.01). Furthermore, when sperm was stored at 4 degrees C, no detrimental effects of seminal plasma were observed. Our results showed that motility parameters can be maintained with success until Day 4. However, NPPC-based extenders extend the in vitro survival to 7 days of storage. The optimal concentration of NPPC for the preservation of sperm cells for 4 days of storage was 81g/l and for 7 days of storage was 81 and 54g/l. No effect of the supplementation of the NPPC extender with BL was found. 相似文献
70.
Most of the evidence for a key role of parasites in structuring communities is based on the idea of a differential susceptibility of host species to infection and its consequences. Recent advances in community ecology suggest that life-history traits of free-living species can be an important determinant of their co-existence within communities. On the other hand, parasites have the potential to indirectly alter the life-history traits of their hosts, such as developmental time or dispersal. We discuss the idea that these indirect effects could influence the structure of free-living and parasite communities. We explore this idea in relation to related concepts including 'parasitic arbitration' and engineering processes. 相似文献