全文获取类型
收费全文 | 35849篇 |
免费 | 2567篇 |
国内免费 | 5094篇 |
专业分类
43510篇 |
出版年
2024年 | 193篇 |
2023年 | 788篇 |
2022年 | 1066篇 |
2021年 | 1241篇 |
2020年 | 1200篇 |
2019年 | 1715篇 |
2018年 | 1368篇 |
2017年 | 1216篇 |
2016年 | 1174篇 |
2015年 | 1144篇 |
2014年 | 1851篇 |
2013年 | 2580篇 |
2012年 | 1495篇 |
2011年 | 1678篇 |
2010年 | 1300篇 |
2009年 | 1652篇 |
2008年 | 1654篇 |
2007年 | 1809篇 |
2006年 | 1566篇 |
2005年 | 1432篇 |
2004年 | 1237篇 |
2003年 | 1167篇 |
2002年 | 1060篇 |
2001年 | 806篇 |
2000年 | 744篇 |
1999年 | 677篇 |
1998年 | 671篇 |
1997年 | 578篇 |
1996年 | 492篇 |
1995年 | 481篇 |
1994年 | 471篇 |
1993年 | 451篇 |
1992年 | 402篇 |
1991年 | 420篇 |
1990年 | 320篇 |
1989年 | 308篇 |
1988年 | 314篇 |
1987年 | 250篇 |
1986年 | 292篇 |
1985年 | 473篇 |
1984年 | 576篇 |
1983年 | 321篇 |
1982年 | 455篇 |
1981年 | 442篇 |
1980年 | 393篇 |
1979年 | 290篇 |
1978年 | 213篇 |
1977年 | 233篇 |
1976年 | 208篇 |
1973年 | 180篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
91.
《Cell》2022,185(20):3753-3769.e18
92.
93.
Salina Y. Saddick 《Saudi Journal of Biological Sciences》2015,22(3):327-331
Mild gestational hyperglycemia (MGH) is a very common complication of pregnancy that is characterized by intolerance to glucose. The association of angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism to MGH has been previously reported. In this study, we evaluated the association between ACE polymorphism and the risk of MGH in a Saudi population. We conducted a case-control study in a population of 100 MGH patients and 100 control subjects. ACE gene polymorphism was analyzed by the novel approach of tetraprimer amplification refractory mutation system (ARMS)-polymerase chain reaction (PCR). The frequency of ACE polymorphism was not associated with either alleles or genotypes in MGH patients. Glucose concentration was found to be significantly associated with the MGH group. Our study suggests that ACE genotypes were not associated with ACE polymorphism in a Saudi population. 相似文献
94.
95.
Samuel M. Imathiu Rumiana V. Ray Matthew I. Back Martin C. Hare Simon G. Edwards 《Journal of Phytopathology》2013,161(7-8):553-561
Fusarium langsethiae is a toxigenic fungal species that has been reported in European small‐grain cereal crops such as oats, wheat and barley. Although its relative contribution to fusarium head blight (FHB) symptoms is not well understood, it is reported to contaminate these cereals with high levels of HT‐2 and T‐2 trichothecenes mycotoxins that are currently under consideration for legislation by the European Commission. Ten commercial oat fields in Shropshire and Staffordshire (two adjacent counties in the Midlands) in the UK were surveyed in the 2006/2007 growing season. Samples were taken from predetermined field locations at Zadoks growth stages 32/33, 69, 77‐85 and 90‐92 for F. langsethiae biomass and HT‐2 and T‐2 toxins quantification. The results from this study showed that oats can be heavily infected with F. langsethiae and have high concentrations of HT‐2 and T‐2 toxins with no apparent FHB symptoms. The regression of HT‐2 + T‐2 toxins on F. langsethiae DNA concentration was highly significant (P < 0.001, r2 = 0.55). The results indicated that although F. langsethiae had no direct effect on crop yield, it may result in indirect economic losses where the grain can be rejected or downgraded as a result of intolerable levels of HT‐2 and T‐2 toxins, which are of human food and animal feed safety concern. The influence of cultural field practices on the infection and HT‐2 and T‐2 toxins accumulation in oats was not clear and warrants further studies to identify the sources of F. langsethiae inoculum and conditions favourable for infection and mycotoxin production. 相似文献
96.
Janitha A. Liyanage David M. Taylor David R. Williams 《Chemical Speciation and Bioavailability》2013,25(2):73-75
ABSTRACTA method has been developed for impregnating alginate-based wound dressings with trace elements required for wound healing and for quantifying the transfer from these dressing to wound fluid (for which a substitute—blood serum—was used in these experiments). Under ideal conditions, up to 85% can be carried across from the tow to the wound fluid. 相似文献
97.
Cynthia Nafula Wakhungu Isaiah Masinde Tabu O. Daniel Otaye Wafula Victor Wasike 《Archives Of Phytopathology And Plant Protection》2017,50(7-8):398-414
A study was carried out to determine Fusarium wilt distribution in Bambara nut farmers’ fields and its management using farm yard manure (FYM). Four villages in Busia County were purposively sampled for the study. The data generated were subjected to analysis of variance and treatment means separated by least significant difference test. Fusarium wilt incidence in the fields ranged from 14.63 to 43.56%. In the greenhouse, FYM reduced the disease incidence by 10.2% and severity by 9.5% on the black landrace and 1.9 and 12.8%, respectively, on the red landrace. In the field, FYM reduced disease incidence by 9.1% and severity by 6.9% on the black landrace and 10.4 and 10.4%, respectively, on the red landrace. Farm yard manure had the lowest area under disease progress curve irrespective of the landrace. The study confirmed the presence of the pathogen in the fields and the ability to manage the disease using FYM. 相似文献
98.
We review the New Caledonian representatives of the Australasian endemic hydroptiline genus Acritoptila, based on examination of a considerable collection of material in the Swedish Museum of Natural History and of types of previously established species. A key for identification of males is given and includes 3 species newly described here: A. parallela
sp. n., A. forficata
sp. n. and A. macrospina
sp. n. For all New Caledonian species, male genitalia are illustrated, and for 5 associated females, distinctive features are illustrated and described. 相似文献
99.
100.