全文获取类型
收费全文 | 74055篇 |
免费 | 7327篇 |
国内免费 | 1536篇 |
专业分类
82918篇 |
出版年
2022年 | 816篇 |
2021年 | 1435篇 |
2020年 | 963篇 |
2019年 | 1197篇 |
2018年 | 1471篇 |
2017年 | 1212篇 |
2016年 | 1688篇 |
2015年 | 2122篇 |
2014年 | 2664篇 |
2013年 | 3034篇 |
2012年 | 3321篇 |
2011年 | 3346篇 |
2010年 | 2090篇 |
2009年 | 1999篇 |
2008年 | 2514篇 |
2007年 | 2390篇 |
2006年 | 2247篇 |
2005年 | 1946篇 |
2004年 | 1802篇 |
2003年 | 1707篇 |
2002年 | 1573篇 |
2001年 | 4931篇 |
2000年 | 4460篇 |
1999年 | 3320篇 |
1998年 | 1118篇 |
1997年 | 1062篇 |
1996年 | 928篇 |
1995年 | 829篇 |
1994年 | 723篇 |
1993年 | 639篇 |
1992年 | 2028篇 |
1991年 | 1774篇 |
1990年 | 1587篇 |
1989年 | 1431篇 |
1988年 | 1218篇 |
1987年 | 1153篇 |
1986年 | 972篇 |
1985年 | 929篇 |
1984年 | 667篇 |
1983年 | 588篇 |
1979年 | 663篇 |
1978年 | 478篇 |
1975年 | 509篇 |
1974年 | 599篇 |
1973年 | 583篇 |
1972年 | 594篇 |
1971年 | 558篇 |
1970年 | 544篇 |
1969年 | 544篇 |
1968年 | 446篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
Tsyganov V. E.; Pavlova Z. B.; Kravchenko L. V.; Rozov S. M.; Borisov A. Y.; Lutova L. A.; Tikhonovich I. A. 《Annals of botany》2000,86(5):975-981
Using ethyl methane sulfonate (EMS) treatment of the seeds ofline SGE, a new mutant of pea (Pisum sativum L.) with alterationsin root development was obtained. The mutant phenotype dependson the density of the growth substrate: on sand (a high densitysubstrate) the mutant forms a small compact curly root systemwhereas on vermiculite (a low density substrate) differencesbetween the root systems of the mutant and wild type plantsare less pronounced. Genetic analysis revealed that the mutantcarries a mutation in a new pea gene designedcrt (curly roots).Gene crt has been localized in pea linkage group V. The mutantline named SGEcrt showed increased sensitivity to exogenousauxin and an increased concentration of endogenous indole-3-aceticacid (IAA) in comparison with the wild type line SGE. Copyright2000 Annals of Botany Company Pisum sativum L., root development, garden pea mutant, curly roots, auxin, environmental stimulus response 相似文献
44.
Effect of precursors on biosynthesis of monensins A and B 总被引:1,自引:0,他引:1
Precursors of monensins (acetate, propionate, butyrate, isobutyrate) affect the total production and the relative proportion of monensins A and B. Addition of propionate into the fermentation medium causes a prevalence of monensin B whereas butyrate and isobutyrate stimulate the production of monensin A and suppress the production of monensin B. 相似文献
45.
Profile of the alpha-bungarotoxin-binding regions on the extracellular part of the alpha-chain of Torpedo californica acetylcholine receptor. 总被引:3,自引:0,他引:3 下载免费PDF全文
The continuous alpha-neurotoxin-binding regions on the extracellular part (residues 1-210) of the alpha-chain of Torpedo californica acetylcholine receptor were localized by reaction of 125I-labelled alpha-bungarotoxin with synthetic overlapping peptides spanning this entire part of the chain. The specificity of the binding was confirmed by inhibition with unlabelled toxin and, for appropriate peptides, with unlabelled anti-(acetylcholine receptor) antibodies. Five toxin-binding regions were localized within residues 1-10, 32-41, 100-115, 122-150 and 182-198. The third, fourth and fifth (and to a lesser extent the first and second) toxin-binding regions overlapped with regions recognized by anti-(acetylcholine receptor) antibodies. The five toxin-binding regions may be distinct sites or, alternatively, different 'faces' in one (or more) sites. 相似文献
46.
47.
L V Gankovskaia A Z Tskhovrebova N A Gvozdeva L V Koval'chuk A N Cheredeev 《Biulleten' eksperimental'no? biologii i meditsiny》1986,102(8):210-213
Fractions containing macrophage migration inhibition factor (MIF) and leucocyte migration inhibition factor (LIF) were obtained using Sephadex G-200 filtration from supernatant fluids of human lymphocyte cultures stimulated by PHA. The fractions were tested for the ability to affect migration and phagocytic activity of target cells. Peripheral blood leucocyte migration capacity was inhibited by the fraction with the molecular mass of 60,000-70,000 D (LIF), while migration activity of mouse peritoneal exudate cells was suppressed by the fraction with the molecular mass of 20,000-30,000 D (MIF). MIF- and LIF-containing fractions increased almost three-fold Fc-receptor-mediated phagocytic activity of neutrophils. 相似文献
48.
V T Kondakov A B Okulov M A Filippkin R Z Tandilava I U Artamonov O A Voronenko A N Sazonov 《Vestnik rentgenologii i radiologii》1991,(4):31-35
The paper is concerned with analysis of the results of intraoperative phlebotesticulography, performed in 50 patients with varicocele of degree I-II during Ivanissevich's operation. The effect of surgical intervention was shown to depend upon the quality of ligation of the testicular vein, some parts of which are anastomosed between themselves. The localization of this anastomosis is revealed by means of intraoperative phlebotesticulography, which permits increasing the results of surgical treatment and predicting a course of a postoperative period. 相似文献
49.
50.
A strain of 1,507 typised donors enables 15.97 average donors to be selected for a thrombocyte transfusion in one of 75 patients selected at random with HLA antibodies being previously determined (1 to 66 donors per patient). HLA compatible donors were found for 72 patients (97.33 per cent). More than 5 HLA compatible donors could be found for 58 patients. The high number of compatible donors is based on the fact that among 1,507 donors there were 156 HLA homozygotes and 556 donors with 3 HLA-A or B-antigens respectively. Compatibility in the ABO-system was not taken into account. 相似文献