全文获取类型
收费全文 | 169890篇 |
免费 | 17057篇 |
国内免费 | 1209篇 |
出版年
2021年 | 1582篇 |
2019年 | 1275篇 |
2018年 | 2429篇 |
2017年 | 2516篇 |
2016年 | 2737篇 |
2015年 | 3074篇 |
2014年 | 3452篇 |
2013年 | 4217篇 |
2012年 | 5389篇 |
2011年 | 5121篇 |
2010年 | 3111篇 |
2009年 | 3003篇 |
2008年 | 3926篇 |
2007年 | 3835篇 |
2006年 | 3804篇 |
2005年 | 6892篇 |
2004年 | 6395篇 |
2003年 | 5274篇 |
2002年 | 3194篇 |
2001年 | 11885篇 |
2000年 | 11532篇 |
1999年 | 8787篇 |
1998年 | 2189篇 |
1997年 | 2328篇 |
1996年 | 2074篇 |
1995年 | 1827篇 |
1994年 | 1726篇 |
1993年 | 1613篇 |
1992年 | 5947篇 |
1991年 | 5601篇 |
1990年 | 5017篇 |
1989年 | 4973篇 |
1988年 | 4445篇 |
1987年 | 3932篇 |
1986年 | 3529篇 |
1985年 | 3426篇 |
1984年 | 2524篇 |
1983年 | 2237篇 |
1982年 | 1582篇 |
1981年 | 1291篇 |
1979年 | 2363篇 |
1978年 | 1800篇 |
1977年 | 1600篇 |
1976年 | 1385篇 |
1975年 | 1630篇 |
1974年 | 1724篇 |
1973年 | 1705篇 |
1972年 | 1594篇 |
1971年 | 1498篇 |
1970年 | 1337篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
S Hoshino M Suzuki T Kakegawa K Imai M Wakita Y Kobayashi Y Yamada 《Comparative biochemistry and physiology. A, Comparative physiology》1988,90(2):355-359
1. Circulating concentrations of iodothyronines, luteinizing hormone(LH), estradiol(E2), progesterone and corticosterone were measured in hens before, during, and after a forced molt induced by fasting. 2. Corticosterone increased at the onset of molt, peaked at the maximal molt and returned to pre- and post-molt levels. LH, E2 and progesterone declined during the molt, and the decline was coincident with the cessation of egg production. 3. Thyroxine(T4), triiodothyronine (T3) and reverse triiodothyronine(rT3) increased during the molt. The increases of T4 and T3 were not abolished even if the forced molt was conducted in mild weather. 相似文献
143.
A Sólyom S Tóth I Holczinger J Vajda Z Tóth R Kálmánchey 《Applied neurophysiology》1985,48(1-6):222-225
Four thalamic and cortical recordings were carried out in 5 patients. The thalamic-evoked potentials were typical and revealed a triphasic complex, but their latencies showed a relatively high standard deviation. They could be divided into two groups according to their latencies, both of which had low SD. These data suggested that there could be two types of latency of thalamic SEP, because the 4 patients' body sizes were very similar. More detailed surface, cortical and depth recordings are needed to resolve these questions. 相似文献
144.
145.
146.
147.
148.
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
149.
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
150.
R Sitia H Kikutani A Rubartelli Y Bushkin J Stavnezer U Hammerling 《Journal of immunology (Baltimore, Md. : 1950)》1982,128(2):712-716
Three different forms of alpha-chains are synthesized by BF0.3 and 615.2, two cloned cell lines derived from the murine B lymphoma 1.29. The three forms of alpha-chains differ in size, pI, cellular location, and rate of turnover. They were identified by means of lactoperoxidase-catalyzed radioiodination, internal 14C or 35S labeling, and immunofluorescence techniques as membrane-bound(alpha m), secreted (alpha s), and intracellular (alpha ic) proteins. Comparison of immunoglobulin products of the two lymphoma lines with those of a hybridoma cell line, Id 150, which secretes IgA of the 1.29 idiotype but lacks membrane IgA, confirmed the assignments of alpha m, alpha s, and alpha ic. Results of biosynthetic labeling of BF0.3, 615.2, and Id 150 in the presence and absence of tunicamycin suggest that the difference in m.w. and charge observed between alpha m and alpha s can be attributed to differences in primary amino acid structure rather than different degrees of glycosylation. 相似文献