全文获取类型
收费全文 | 1436篇 |
免费 | 89篇 |
国内免费 | 63篇 |
专业分类
1588篇 |
出版年
2024年 | 4篇 |
2023年 | 38篇 |
2022年 | 68篇 |
2021年 | 107篇 |
2020年 | 33篇 |
2019年 | 44篇 |
2018年 | 40篇 |
2017年 | 37篇 |
2016年 | 27篇 |
2015年 | 62篇 |
2014年 | 77篇 |
2013年 | 99篇 |
2012年 | 47篇 |
2011年 | 32篇 |
2010年 | 27篇 |
2009年 | 46篇 |
2008年 | 44篇 |
2007年 | 76篇 |
2006年 | 74篇 |
2005年 | 57篇 |
2004年 | 47篇 |
2003年 | 43篇 |
2002年 | 39篇 |
2001年 | 41篇 |
2000年 | 36篇 |
1999年 | 34篇 |
1998年 | 38篇 |
1997年 | 32篇 |
1996年 | 24篇 |
1995年 | 26篇 |
1994年 | 18篇 |
1993年 | 22篇 |
1992年 | 12篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 11篇 |
1988年 | 10篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1985年 | 12篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 15篇 |
1980年 | 13篇 |
1979年 | 5篇 |
1978年 | 12篇 |
1977年 | 5篇 |
1975年 | 3篇 |
1973年 | 1篇 |
排序方式: 共有1588条查询结果,搜索用时 15 毫秒
191.
J. R. Ryan K. Dave E. Emmerich L. Garcia L. Yi R. E. Coleman J. Sattabongkot R. F. Dunton A. S. T. Chan R. A. Wirtz 《Medical and veterinary entomology》2001,15(2):225-230
Malaria remains the most serious vector-borne disease, affecting some 300-500 million people annually, transmitted by many species of Anopheles mosquitoes (Diptera: Culicidae). Monoclonal antibodies developed against specific circumsporozoite (CS) proteins of the main malaria parasites Plasmodium falciparum and P. vivax have been used previously for enzyme-linked immunosorbent assays (ELISA), widely employed for detection of malaria sporozoites in vector Anopheles for local risk assessment, epidemiological studies and targeting vector control. However, ELISA procedures are relatively slow and impractical for field use. To circumvent this, we developed rapid wicking assays that identify the presence or absence of specific peptide epitopes of CS protein of the most important P. falciparum and two strains (variants 210 and 247) of the more widespread P. vivax. The resulting assay is a rapid, one-step procedure using a 'dipstick' wicking test strip. In laboratory assessment, dipsticks identified 1 ng/ mL of any of these three CS protein antigens, with sensitivity nearly equal to the CS standard ELISA. We have developed and are evaluating a combined panel assay that will be both qualitative and quantitative. This quick and easy dipstick test (VecTest Malaria) offers practical advantages for field workers needing to make rapid surveys of malaria vectors. 相似文献
192.
To determine the occurrence of variants of African cassava mosaic virus, 316 cassava leaf samples were collected from mosaic‐affected cassava plants in 254 farmers. fields in 1997 and 1998, covering the humid forest, coastal/derived, southern Guinea and northern Guinea savannas and arid and semi‐arid agroecologies of Nigeria. The samples were tested in triple antibody sandwich enzyme‐linked immunosorbent assay using a panel of 10 monoclonal antibodies (MAbs) against the virus in which 29 reaction patterns were observed. In cluster analysis, nine serotypes were obtained at 0.80 Jaccard similarity coefficient index in which at least 50% of isolates of each serotype reacted alike. The serotypes ranged between two extremes: serotype 1 with 90% isolates reacting with the 10 MAbs and serotype 8 in which 90% of its isolates failed to react with the antibodies. Isolates of serotypes 1, 2, 4 and 8 were widely distributed while those of the other serotypes were estricted to certain agroecologies. Four representative isolates 227 (serotype 1), 231 (serotype 2), 235 and 283 (serotype 8) elicited different responses in Nicotiana, benthamiana, with isolate 283 not able to infect this and other test plants used. The serological variations did not necessarily reflect the biological variations. In polymerase chain reaction tests, one out of the five pairs of ACMV primers tested distinguished only isolate 283. The humid forest, derived/coastal and southern Guinea savannas where most of the crop is grown in Nigeria had a high number of variants, which makes the agroecologies suitable for the selection of resistant cassava clones against ACMV. 相似文献
193.
F.C.F. Yau K.L. Wong P.C. Shaw P.P.H. But J. Wang 《Biodiversity and Conservation》2002,11(9):1653-1662
Random amplified polymorphic DNA fingerprints characteristic of thethree snakes Zaocys dhumnades, Agkistrodonacutus and Bungarus multicinctus multicinctuswere generated using primer OPF-14. Z. dhumnades is anendangered species included in the Convention on International Trade inEndangered Species of Wild Fauna and Flora, and A. acutus,B. multicinctus multicinctus and Z. dhumnades are listed inthe Chinese Pharmacopoeia. The species-specific polymorphic bands Aa specific toA. acutus, Bmm specific to B. multicinctusmulticinctus and Zd specific to Z. dhumnadeswere identified and the sequences of these bands were used to design polymerasechain reaction primers for sequence characterized amplified region (SCAR)analysis of the three snakes. A multiplex SCAR analysis was established toauthenticate the snakes used in Chinese medicine reliably and efficiently. 相似文献
194.
肿瘤仍然是导致人类死亡的重要原因,由于缺乏深刻了解癌症的发生机制,尽管在过去25年中肿瘤的诊断和治疗都取得很大的进展,但肿瘤病人的存活率并没有显著的提高。目前有很多癌基因和抑癌基因如P16、P53、P73、ras、DCC和RB等 相似文献
195.
Serum samples of Meishan (13 animals) and Meishan x Wild Boar crosses (361 animals) were analysed by means of two-dimensional electrophoresis. Some new variants in protease inhibitor systems PO1A, PO1B and PI2 are reported. 相似文献
196.
A method for estimating and comparing population genetic variation using random amplified polymorphic DNA (RAPD) profiling is presented. An analysis of molecular variance (AMOVA) is extended to accomodate phenotypic molecular data in diploid populations in Hardy-Weinberg equilibrium or with an assumed degree of selfing. We present a two step strategy: 1) Estimate RAPD site frequencies without preliminary assumptions on the unknown population structure, then perform significance testing for population substructuring. 2) If population structure is evident from the first step, use this data to calculate better estimates for RAPD site frequencies and sub-population variance components. A nonparametric test for the homogeneity of molecular variance (HOMOVA) is also presented. This test was designed to statistically test for differences in intrapopulational molecular variances (heteroscedasticity among populations). These theoretical developments are applied to a RAPD data set in Vaccinium macrocarpon (American cranberry) using small sample sizes, where a gradient of molecular diversity is found between central and marginal populations. The AMOVA and HOMOVA methods provide flexible population analysis tools when using data from RAPD or other DNA methods that provide many polymorphic markers with or without direct allelic data. 相似文献
197.
198.
《Cell》2021,184(24):5970-5984.e18
199.
《Cell》2021,184(23):5699-5714.e11
200.