全文获取类型
收费全文 | 100031篇 |
免费 | 798篇 |
国内免费 | 884篇 |
专业分类
101713篇 |
出版年
2023年 | 85篇 |
2022年 | 66篇 |
2021年 | 145篇 |
2020年 | 116篇 |
2019年 | 119篇 |
2018年 | 12074篇 |
2017年 | 10869篇 |
2016年 | 7731篇 |
2015年 | 861篇 |
2014年 | 618篇 |
2013年 | 863篇 |
2012年 | 4748篇 |
2011年 | 13356篇 |
2010年 | 12299篇 |
2009年 | 8427篇 |
2008年 | 9939篇 |
2007年 | 11473篇 |
2006年 | 482篇 |
2005年 | 610篇 |
2004年 | 1097篇 |
2003年 | 1123篇 |
2002年 | 855篇 |
2001年 | 354篇 |
2000年 | 263篇 |
1999年 | 139篇 |
1998年 | 92篇 |
1997年 | 99篇 |
1996年 | 86篇 |
1995年 | 87篇 |
1994年 | 75篇 |
1993年 | 94篇 |
1992年 | 100篇 |
1991年 | 107篇 |
1990年 | 63篇 |
1989年 | 80篇 |
1988年 | 67篇 |
1987年 | 79篇 |
1986年 | 58篇 |
1985年 | 75篇 |
1984年 | 68篇 |
1983年 | 83篇 |
1982年 | 61篇 |
1981年 | 69篇 |
1980年 | 58篇 |
1979年 | 80篇 |
1977年 | 62篇 |
1975年 | 57篇 |
1974年 | 59篇 |
1972年 | 285篇 |
1971年 | 302篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Ultrathin sections were prepared from the tissues of lettuce leaves with mosaic-like symptoms and thickened nervature which were studied by means of electron microscopy. Intracellular inclusions surrounded by a membrane were found in the cytoplasm of parenchym cells of the investigated lettuce leaves(Lactuca saliva L. provar.capitata L. nid.jaggeri Helm., cv. Pra?an). Crystals with a distinctly apparent hexagonal lattice could be observed in the inclusions. No crystal containing inclusions were found in the tissues from the leaves without mosaic-like symptoms and in those from thickened nervature. 相似文献
92.
Some properties of pea enation mosaic virus isolated from field pea and broad bean plants in Bohemia
Pea enation mosaic virus (PEMV) was isolated from disea sed field pea (Pisum sativum L.ssp. arvense A.Gr.) and broad bean (Faba vulgaris Moench) plants grown as filed crops at Bohumilice in Bohemia. The virus proved to be pathogenic for the following plant species:Pisum sativum L. cv. Raman,Faba vulgaris Moench,Lens culinaris Med.,Vicia sativa L.,Lathyrus odoratus L.,Glycine soja L.,Phaseolus vulgaris L.,Chenopodium amaranticolor Coste andReyn,Nicotiana clevelandi Gray,Trifolium incarnatum L. The dilution end point of the isolate was higher in pea plants (10?4) than in broad bean plants (10?2). The thermal inactivation point was 65–68° and the longevityin vitro between 10 and 14 days. According to the host range, symptoms on pea plants and physical properties the virus isolate studied resembles some isolates described in the U.S.A. and represents a PEMV strain different from those reported so far in Czechoslovakia. 相似文献
93.
Synthesis of two hydroxy-derivatives of nalidixic acid as a result of microbial transformation was demonstrated in certain
species of the genusAspergillus. Aspergillus alliaceus produced 7-hydroxy-nalidixic acid andAspergillus niger 6-hydroxy-nalidixic acid. It was demonstrated that the antibacterial activity of both hydroxy-derivatives (tested inEscherichia coli) was lower than that of the initial nalidixis acid. 相似文献
94.
In a model secondary reactionin vitro, a correlation was demonstrated between the size of the antigen dose used for the prestimulation of spleen tissue donors
and the type of antibodies formed in the anamnestic reaction. After a small dose of antigen ΦX 174, the antibody response
three days after prestimulation was of the 19 S (IgM) type, but later secondary contactin vitro (after four months) did not produce a 19 S anamnestic reaction. After large primary doses of antigen, a short interval between
primary and secondary contact led to the formation of 19 and 7 S type antibodies, while after a long interval only 7 S (IgG)
type antibodies were formed. The results are discussed in relation to differences in the size of the antigen dose needed to
induce short-term 19 S and long-term 7 S immunological memory. 相似文献
95.
Karel Beneš 《Biologia Plantarum》1962,4(1):61-68
V této práci byly aplikovány na rostlinných objektech reakce s β-oxynaftyl-merkurichloridem a p-nitrobromacetofenonem, popsané k pr?kazu bílkovinných SH na materiálu ?ivo?i?ném. V rostlinných meristematických buňkách obě tyto techniky stejně jako DDD1 a RSR1 jeví vět?inou intensivněj?í zbarvení jader ne? cytoplasmy. Rovně? po aplikaci reakcí na bílkovinné karboxyly a tyrosin je jádro intensivněji zbarveno ne? cytoplasma. Z toho lze soudit, ?e rozdíly v intensitě zbarvení jádra a cytoplasmy v meristematických buňkách rostlinných technikami k pr?kazu bílkovinných SH jsou zp?sobeny spí? rozdílem v celkové koncentraci bílkovin ne? zv??ením podílu cysteinu v jaderných bílkovinách. 相似文献
96.
97.
International Journal of Biometeorology - 相似文献
98.
99.
Antiserum был подготовлен противингибитор вируса haemagglutination (IVH)одна из эмбриона chorioallantoic мембр анныепутем иммун изации морских св инокЭто анти-инги битора в сыворотке заблокирован ингибирование IVH из chorioallantoicмембран в haemagglutination испытанияно ника кого влияния на ре цепторы эритроци товСыворотке кро] ви не влияет рост chorioallantoic мембраны клет ок инет нейтрализ овать воздействи е на вирус гриппа Она снизилась спо собность chorioallantoic мембр ан для adsorb вируса гри ппа, а также степен ь размножения вир усав такого рода тканиАвторы хоте ли бы поблагодари ть г-н Г. Ruttkay-Ne -палубе и для проведения эле ктрофореза меру ния. 相似文献
100.