全文获取类型
收费全文 | 1084篇 |
免费 | 40篇 |
出版年
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 10篇 |
2020年 | 12篇 |
2019年 | 11篇 |
2018年 | 18篇 |
2017年 | 12篇 |
2016年 | 20篇 |
2015年 | 21篇 |
2014年 | 35篇 |
2013年 | 57篇 |
2012年 | 63篇 |
2011年 | 60篇 |
2010年 | 38篇 |
2009年 | 53篇 |
2008年 | 73篇 |
2007年 | 84篇 |
2006年 | 74篇 |
2005年 | 73篇 |
2004年 | 83篇 |
2003年 | 68篇 |
2002年 | 52篇 |
2001年 | 19篇 |
2000年 | 22篇 |
1999年 | 15篇 |
1998年 | 9篇 |
1997年 | 16篇 |
1996年 | 11篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1992年 | 3篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1975年 | 2篇 |
1973年 | 3篇 |
1971年 | 4篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1965年 | 2篇 |
排序方式: 共有1124条查询结果,搜索用时 281 毫秒
101.
Marine conservation programs in Oceania are increasingly turning to precautionary and adaptive management, particularly approaches
which emphasize local participation and customary management. Although the application of community-based natural resource
management is widespread in the region, the full integration of local knowledge and practices into the design, implementation,
and monitoring of community-based conservation programs has been limited. There is also little empirical data to show whether
or not community-based conservation projects are meeting their stated objectives. This paper summarizes an integrated method
for selecting Marine Protected Area (MPA) sites and presents empirical evidence that illustrates how an MPA that was largely
conceived using indigenous ecological knowledge and existing sea tenure governance (i.e., customary management practices),
as part of a regional precautionary and adaptive community-based management plan, is showing signs of biological and social
success. More generally, the paper shows how hybrid natural and social research approaches in tandem with customary management
for designing MPAs can protect coral reefs in Oceania. 相似文献
102.
Masamichi Takahashi Hitomi Furusawa Pitayakon Limtong Vanlada Sunanthapongsuk Dokrak Marod Samruan Panuthai 《Ecological Research》2007,22(1):160-164
We have examined the surface (0–10 cm) soil characteristics of sites after bamboo (Cephalostachyum pergracile) mass flowering and death (DB sites) in comparison with sites with living bamboo (Bambusa tulda) (LB sites) in a seasonal tropical forest in Thailand. One year after bamboo flowering the DB sites were acidic with lower
concentrations of exchangeable Ca and Mg and soil nitrogen than the LB sites. Therefore, although leaf and root litter of
the dead bamboo was deposited in the DB sites after bamboo flowering, soil nutrient status decreased. 相似文献
103.
104.
Miyata Seiko Noda Akiko Iwamoto Kunihiro Kawano Naoko Banno Masahiro Tsuruta Yoshiyuki Noda Yukihiro Ozaki Norio 《Sleep and biological rhythms》2015,13(4):387-394
Sleep and Biological Rhythms - Chronic sleep restriction adversely effects cognitive performance and mood, resulting in accidents and economic loss. We examined the effects of three nights of sleep... 相似文献
105.
Nagai H Goto T Takahashi N Kusudoh T Deyashiki Y Esaka Y Kawada T 《Bioscience, biotechnology, and biochemistry》2011,75(8):1485-1489
A useful method employing liquid chromatography mass spectrometry (LC/MS) and a stable isotope was developed for simultaneous examination of major metabolism in adipocytes, de novo fatty acid synthesis, glycerol output, and glucose uptake with high sensitivity. The addition of thiazolidinediones, potent agonists of peroxisome proliferator-activated receptors-γ, for 10 d increased glucose uptake in a dose-dependent manner. Fatty acid (FA) synthesis increased at low concentrations of thiazolidinediones (TZDs) and decreased at high concentrations. It is important to assess adipocytes from various examples of metabolism, because each example of adipocyte metabolism is directly related to obesity or metabolic syndrome in various ways. The technique makes metabolic examination easier than conventional methods by means of radioisotopes and makes it possible to identify metabolites and to apply them in biomarker screening. 相似文献
106.
Itoh Y Kitaguchi R Ishikawa M Naito M Hashimoto Y 《Bioorganic & medicinal chemistry》2011,19(22):6768-6778
Compounds that regulate the function(s) of nuclear receptors (NRs) are useful for biological studies and as candidate therapeutic agents. Most such compounds are agonists or antagonists. On the other hand, we have developed specific protein degradation inducers, which we designated as SNIPERs (Specific and Nongenetic IAPs-dependent Protein ERasers), for selective degradation of target proteins. SNIPERs are hybrid molecules consisting of an appropriate ligand for the protein of interest, coupled to a ligand for inhibitor of apoptosis proteins (IAPs), which target the bound protein for polyubiquitination and proteasomal degradation. We considered that protein knockdown with SNIPERs would be a promising alternative approach for modulating NR function. In this study, we designed and synthesized degradation inducers targeting retinoic acid receptor (RAR), estrogen receptor (ER), and androgen receptor (AR). These newly synthesized RAR, ER, and AR SNIPERs, 9, 11, and 13, respectively, were confirmed to significantly reduce the levels of the corresponding NRs in live cells. 相似文献
107.
Yoshida M Mori A Morimoto S Kotani E Oka M Notoya K Makino H Ono M Shirasaki M Tada N Fujita H Ban J Ikeda Y Kawamoto T Goto M Kimura H Baba A Yasuma T 《Bioorganic & medicinal chemistry》2011,19(6):1881-1894
The calcium-sensing receptor antagonist (CaSR) has been recognized as a promising target of anabolic agents for treating osteoporosis. In the course of developing a new drug candidate for osteoporosis, we found tetrahydropyrazolopyrimidine derivative 1 to be an orally active CaSR antagonist that stimulated transient PTH secretion in rats. However, compound 1 showed poor physical and chemical stability. In order to work out this compound's chemical stability and further understand its in vivo efficacy, we focused on modifying the 2-position of the tetrahydropyrazolopyrimidine. As a result of chemical modification, we discovered (5R)-N-[1-ethyl-1-(4-ethylphenyl)propyl]-2,7,7-trimethyl-5-phenyl-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrimidine-3-carboxamide monotosylate 10m (TAK-075), which showed improved solubility, chemical stability, and in vivo efficacy. Furthermore, we describe that evaluating the active metabolite is important during repeated treatment with short-acting CaSR antagonists. 相似文献
108.
Junko Morimoto Kento Hirabayashi Emu Mizumoto Takehiko Katsuno Yukihiro Morimoto 《Landscape and Ecological Engineering》2011,7(2):185-193
To develop an appropriate method of conservation for native Rhododendron sections Brachycalyx and Tsutsusi, the symbol of Satoyama, field experiments were performed in the dry granite region of Japan. When carpet-type landscape
of native rhododendrons was desired, all plants were cut at 20 cm above the ground level of all trees and shrubs, and herbs
and ferns were weeded (once and three times, respectively). When shrubby-type landscape of native rhododendrons was desired,
all plants, excluding native rhododendrons, were cut at 20 cm above the ground level of all trees and shrubs, herbs and ferns
were weeded, and litter was swept. After 3 years of monitoring of the percentage and depth of crowns with flower buds, the
following major results were obtained: Cutting all plants excluding native rhododendrons was effective to maintain the depth
of crowns with flower buds. However, weeding and sweeping of litter on the ground caused desiccation of surface soil, which
induced a transitory decrease in the percentage of crowns with flower buds. One weeding was effective in maintaining the depth
of crowns with flower buds; however, the second and third weedings had no distinct effect. In dry granite regions, considerable
attention to desiccation of surface soil is critical, as opposed to limiting attention to maintenance of sunlight as is common
practice. 相似文献
109.
Hiyoshi H Kodama T Saito K Gotoh K Matsuda S Akeda Y Honda T Iida T 《Cell host & microbe》2011,10(4):401-409
Vibrio parahaemolyticus, a Gram-negative halophilic bacterium that causes acute gastroenteritis in humans, is characterized by two type III secretion systems (T3SS), namely T3SS1 and T3SS2. T3SS2 is indispensable for enterotoxicity but the effector(s) involved are unknown. Here, we identify VopV as a critical effector that is required to mediate V. parahaemolyticus T3SS2-dependent enterotoxicity. VopV was found to possess multiple F-actin-binding domains and the enterotoxicity caused by VopV correlated with its F-actin-binding activity. Furthermore, a T3SS2-related secretion system and a vopV homologous gene were also involved in the enterotoxicity of a non-O1/non-O139 V. cholerae strain. These results indicate that the F-actin-targeting effector VopV is involved in enterotoxic activity of T3SS2-possessing bacterial pathogens. 相似文献
110.
Lasley RD Keith BJ Kristo G Yoshimura Y Mentzer RM 《American journal of physiology. Heart and circulatory physiology》2005,289(2):H785-H791
Adenosine A1 receptor delayed preconditioning (PC) against myocardial infarction has been well described; however, there have been limited investigations of the signaling mechanisms that mediate this phenomenon. In addition, there are multiple conflicting reports on the role of inducible nitric oxide synthase (iNOS) in mediating A1 late-phase PC. The purpose of this study was to determine the roles of the p38 and extracellular signal-regulated kinase (ERK) mitogen-activated protein kinases (MAPKs) in in vivo delayed A1 receptor PC and whether this protection at the myocyte level is due to upregulation of iNOS. Myocardial infarct size was measured in open-chest anesthetized rats 24 h after treatment with vehicle or the adenosine A1 agonist 2-chloro-N6-cyclopentyladenosine (CCPA; 100 microg/kg ip). Additional rats receiving CCPA were pretreated with the p38 inhibitor SB-203580 (1 mg/kg ip) or the MAPK/ERK kinase (MEK) inhibitor PD-098059 (0.5 mg/kg ip). At 24 h after CCPA administration, a group of animals was given the iNOS inhibitor 1400 W 10 min before ischemia. Treatment with CCPA reduced infarct size from 48 +/- 2 to 28 +/- 2% of the area at risk, an effect that was blocked by both SB-203580 and PD-098059 but not 1400 W. Ventricular myocytes isolated 24 h after CCPA injection exhibited significantly reduced oxidative stress during H2O2 exposure compared with myocytes from vehicle-injected animals, and this effect was not blocked by the iNOS inhibitor 1400 W. Western blot analysis of whole heart and cardiac myocyte protein samples revealed no expression of iNOS 6 or 24 h after CCPA treatment. These results indicate that adenosine A1 receptor delayed PC in rats is mediated by MAPK-dependent mechanisms, but this phenomenon is not associated with the early or late expression of iNOS. 相似文献