全文获取类型
收费全文 | 603894篇 |
免费 | 64964篇 |
国内免费 | 239篇 |
专业分类
669097篇 |
出版年
2018年 | 6097篇 |
2017年 | 5882篇 |
2016年 | 7629篇 |
2015年 | 9344篇 |
2014年 | 11350篇 |
2013年 | 16328篇 |
2012年 | 18507篇 |
2011年 | 19242篇 |
2010年 | 13275篇 |
2009年 | 12051篇 |
2008年 | 17126篇 |
2007年 | 17741篇 |
2006年 | 16693篇 |
2005年 | 15994篇 |
2004年 | 15730篇 |
2003年 | 15386篇 |
2002年 | 15133篇 |
2001年 | 26994篇 |
2000年 | 26830篇 |
1999年 | 21169篇 |
1998年 | 7182篇 |
1997年 | 7598篇 |
1996年 | 7214篇 |
1995年 | 6704篇 |
1994年 | 6584篇 |
1993年 | 6618篇 |
1992年 | 17795篇 |
1991年 | 17736篇 |
1990年 | 17162篇 |
1989年 | 17005篇 |
1988年 | 15613篇 |
1987年 | 14930篇 |
1986年 | 13948篇 |
1985年 | 14054篇 |
1984年 | 11604篇 |
1983年 | 9900篇 |
1982年 | 7343篇 |
1981年 | 6495篇 |
1980年 | 6275篇 |
1979年 | 10831篇 |
1978年 | 8581篇 |
1977年 | 7843篇 |
1976年 | 7478篇 |
1975年 | 8448篇 |
1974年 | 8923篇 |
1973年 | 8838篇 |
1972年 | 7926篇 |
1971年 | 7385篇 |
1970年 | 6203篇 |
1969年 | 5972篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
Joshua R Edwards Evangelos A Diamantakos Jacob D Peuler Peter C Lamar Walter C Prozialeck 《BMC physiology》2007,7(1):1
Background
Ethidium homodimer is a cell-membrane impermeant nuclear fluorochrome that has been widely used to identify necrotic cells in culture. Here, we describe a novel technique for evaluating necrosis of epithelial cells in the proximal tubule that involves perfusing ethidium homodimer through the intact rat kidney. As a positive control for inducing necrosis, rats were treated with 3.5, 1.75, 0.87 and 0.43 mg/kg mercuric chloride (Hg2+, intraperitoneal), treatments which have previously been shown to rapidly cause dose-dependent necrosis of the proximal tubule. Twenty-four h after the administration of Hg2+, ethidium homodimer (5 μM) was perfused through the intact left kidney while the animal was anesthetized. The kidney was then removed, placed in embedding medium, frozen and cryosectioned at a thickness of 5 μm. Sections were permeabilized with -20°C methanol and then stained with 4',6-diamidino-2-phenylindole (DAPI) to label total nuclei. Total cell number was determined from the DAPI staining in random microscopic fields and the number of necrotic cells in the same field was determined by ethidium homodimer labeling. 相似文献993.
Sandhya Ravishankar Meera Pandey R. P. Tewari V. Krishna 《World journal of microbiology & biotechnology》2006,22(10):1021-1025
Summary The sporophores of Pleurotus are gymnocarpous and continuously release spores in the atmosphere causing respiratory allergies like hay fever and farmer’s lung disease among workers. The allergy is caused by the antigens present on the walls of the spores. Apart from this, during commercial production, these spores settle on the fruit bodies, germinate and form a velvety film which gives an unpleasant appearance to the mushrooms. The spores emitted may include new genotypes likely to attack wood or trees. Spore allergy is one of the most important limiting factors for the large scale cultivation of this species. Different approaches are being adopted at IIHR for the production of commercial sporeless/low-sporing strains of Pleurotus to alleviate the spore allergy problem. Attempts were made during the present investigation to produce sporeless or low-sporing mutants through u.v. mutation. Mutation of the mycelium did not yield the desired results. Mutation of the spores of Pleurotus sajor-caju yielded an extremely low-sporing mutant after 75 min exposure. The character has been found to be stable for more than 10 generations of subculturing. 相似文献
994.
Jan Suchá?ek Petr Sed’a Václav Friedrich Renata Wachowiak-Smolíková Mark P. Wachowiak 《PloS one》2016,11(11)
Media, and particularly TV media, have a great impact on the general public. In recent years, spatial patterns of information and the relevance of intangible geographies have become increasingly important. Gatekeeping plays a critical role in the selection of information that is transformed into media. Therefore, gatekeeping, through national media, also co-forms the generation of mental maps. In this paper, correspondence analysis (a statistical method) combined with cloud lines (a new visual analytics technique) is used to analyze how individual major regional events in one of the post-communist countries, the Czech Republic, penetrate into the media on a national scale. Although national news should minimize distortions about regions, this assumption has not been verified by our research. Impressions presented by the media of selected regions that were markedly influenced by one or several events in those regions demonstrate that gatekeepers, especially news reporters, functioned as a filter by selecting only a few specific, and in many cases, unusual events for dissemination. 相似文献
995.
The epididymis of buffalo is differentiated into 6 regions. The head represents the first 3 regions, the body the 4th region and the tail the 5th and 6th region. At 3-30 weeks, the epithelium is simple high columnar with few basal cells in region I, simple low columnar with few basal cells in region II, pseudostratified low columnar in regions III, IV, V, and pseudostratified low columar in region VI. As age advances, the epithelium increases in height and shows a tendency toward advanced pseudostratification. The basal cells are greater in number in regions III, IV and V than in the other regions of the epididymis. The epithelial cells contain stereocilia in region I at 3 weeks and regions III, IV and V at 30 weeks, whereas they are absent in regions II and VI. The tubules in region I are the smallest in diameter while the tubules in region VI have the largest diameter. 相似文献
996.
997.
998.
999.
The use of the artificial antigen abequosylmannoside copolymer with acrylamide in the enzyme immunoassay for the determination of antibodies in the sera of salmonellosis patients has enhanced the specificity of the serological diagnosis of group B salmonellosis in comparison with the use of the natural antiren, S. typhimurium lipopolysaccharide. 相似文献
1000.