全文获取类型
收费全文 | 4319篇 |
免费 | 317篇 |
国内免费 | 1篇 |
出版年
2022年 | 18篇 |
2021年 | 78篇 |
2020年 | 35篇 |
2019年 | 52篇 |
2018年 | 103篇 |
2017年 | 100篇 |
2016年 | 152篇 |
2015年 | 207篇 |
2014年 | 216篇 |
2013年 | 272篇 |
2012年 | 317篇 |
2011年 | 316篇 |
2010年 | 219篇 |
2009年 | 192篇 |
2008年 | 225篇 |
2007年 | 233篇 |
2006年 | 201篇 |
2005年 | 196篇 |
2004年 | 179篇 |
2003年 | 135篇 |
2002年 | 139篇 |
2001年 | 106篇 |
2000年 | 63篇 |
1999年 | 57篇 |
1998年 | 45篇 |
1997年 | 24篇 |
1996年 | 30篇 |
1995年 | 31篇 |
1994年 | 26篇 |
1993年 | 24篇 |
1992年 | 40篇 |
1991年 | 25篇 |
1990年 | 36篇 |
1989年 | 35篇 |
1988年 | 27篇 |
1987年 | 36篇 |
1986年 | 19篇 |
1985年 | 22篇 |
1984年 | 24篇 |
1983年 | 21篇 |
1982年 | 19篇 |
1981年 | 18篇 |
1977年 | 21篇 |
1976年 | 22篇 |
1975年 | 27篇 |
1974年 | 19篇 |
1973年 | 20篇 |
1971年 | 17篇 |
1969年 | 16篇 |
1966年 | 17篇 |
排序方式: 共有4637条查询结果,搜索用时 15 毫秒
11.
12.
C. R. Vonk E. Davelaar S. A. Ribôt B. Shadid H. C. Van der Plas 《Plant Growth Regulation》1989,8(3):263-276
It is shown that in bulbous Iris zeatin originates from a nucleotide. This nucleotide is probably zeatin-allylic-phosphate, in which a phosphate group is attached to the isoprenoid side-chain of zeatin. The formation of zeatin-allylic-phosphate from t-zeatin and 8-[14C]-zeatin by the microsomal fractions of Iris bulb disks and Helianthus tubers was demonstrated. The responsible enzyme was partially purified. 5-AMP was found to be a phosphate group delivering substrate. Adenosine and adenine inhibited the enzyme reaction. The significance of the results is discussed in relation to cytokinin biosynthesis and the occurrence of bud blast in Iris. 相似文献
13.
C C?té D Tremblay H Riverin P Frémont P A Rogers 《Canadian journal of physiology and pharmacology》1989,67(6):645-649
We tested the effects of inhibiting the carbonic anhydrase activity of rat soleus and extensor digitorum longus muscles on the isometric contractile properties and the resistance to fatigue. SOL and EDL muscles from female rats were incubated in vitro in the presence of methazolamide, a specific inhibitor of carbonic anhydrase, before determining their contractile properties. Methazolamide had no effects on the contractile properties of the soleus muscle (10(-5) or 10(-3) M) and extensor digitorum longus (10(-3) M), except for the half-relaxation time of the soleus muscle which increased significantly. Values for half-relaxation time were significantly increased with both concentrations of the inhibitor. Muscles were then submitted to a fatigue protocol lasting 30 min. During the fatigue test, no significant difference was observed between control and 10(-5) M methazolamide soleus muscles. In presence of 10(-3) M methazolamide however, the soleus muscle showed a significantly increased resistance to fatigue compared with control preparations. No significant effect was observed with the extensor digitorum longus muscle exposed to 10(-3) M methazolamide. Results are discussed in terms of the presence of two different isoforms of carbonic anhydrase that may be associated with calcium uptake and energy metabolic processes, respectively. 相似文献
14.
Benoît Verjans Frederic Hollande Colette Moreau Claudine Lejeune Christophe Erneux 《Cellular signalling》1990,2(6):595-599
Inositol 1,4,5-trisphosphate 5-phosphatase catalyses the dephosphorylation of the phosphate in the 5-position from inositol 1,4,5-trisphosphate and inositol 1,3,4,5-tetrakisphosphate. One particulate and two soluble enzymes were previously described in bovine brain. In this study, we have obtained a precipitating antiserum against soluble type I inositol 1,4,5-trisphosphate 5-phosphatase. The particulate, but not the soluble type II enzyme, was immunoprecipitated by the serum. Inositol 1,4,5-triphosphate 5-phosphatase activity from crude extracts of rat brain, human platelets and rat liver were immmunoprecipitated by the same antibodies, suggesting the existence of common antigenic determinant among inositol 1,4,5-trisphosphate 5-phosphatases of diverse sources. 相似文献
15.
Sequence and structure of the mouse gene coding for the largest neurofilament subunit 总被引:17,自引:0,他引:17
We have determined the complete nucleotide sequence of the mouse gene encoding the neurofilament NF-H protein. The C-terminal domain of NF-H is very rich in charged amino acids (aa) and contains a 3-aa sequence, Lys-Ser-Pro, that is repeated 51 times within a stretch of 368 aa. The location of this serine-rich repeat in the phosphorylated domain of NF-H indicates that it represents the major protein kinase recognition site. The nfh gene shares two common intron positions with the nfl and nfm genes, but has an additional intron that occurs at a location equivalent to one of the introns in non-neuronal intermediate filament-coding genes. This additional nfh intron may have been acquired via duplication of a primordial intermediate filament gene. 相似文献
16.
Marie-Laure Yaspo Nathalie Crété Zoubida Chettouh Jean-Louis Blouin Zohra Rahmani Dominique Stehelin Pierre-Marie Sinet Nicole Créau-Goldberg Jean-Maurice Delabar 《Human genetics》1992,90(4):427-434
To generate new chromosome 21 markers in a region that is critical for the pathogenesis of Down syndrome (D21S55-MX1), we used pulsed field gel electrophoresis (PFGE) to isolate a 600-kb NruI DNA fragment from the WA17 hybrid cell line, which has retained chromosome 21 as the only human material. This fragment, which contains the oncogene ETS2, was used to construct a partial genomic library. Among the 14 unique sequences that were isolated, 3 were polymorphic markers and contained sequences that are conserved in mammals. Five of these markers mapped on the ETS2-containing NruI fragment and allowed us to define an 800-kb high-resolution PFGE map. 相似文献
17.
Evidence is accumulating that the two major families of interspersed repeated human DNA sequences, Alu and L1, are not randomly distributed. However, only limited information is available on their relative long-range distribution. We have analyzed a set of randomly selected, human Chromosome (Chr) 11-specific YAC recombinants constituting a total length of about 2 Mbp for the local and global distribution of Alu and L1 repeats: the data show a strong asymmetry in the distribution of these two repeat classes and give weight, at the long-range molecular level, to previous studies indicating their partition in the human genome; they also suggest a strong tendency for L1 repeats to cluster, with a higher proportion of full-length elements than expected. 相似文献
18.
L P Panchenko O V Egorov I G Skripal' A S Ra?t E M Ivanova V F Zarytova V V Vlasov 《Mikrobiologicheekij zhurnal》1991,53(4):58-63
Stability of alkylating derivatives of decathymidylates protected on the 3'-terminal by cholesterol and phenazine residues has been studied in the process of their interaction with cells of Acholeplasma laidlawii PG-8. It is shown that the studied reagents are not split by nucleases of A. laidlawii PG-8 for the time necessary for alkylation of mycoplasma biopolymers. 相似文献
19.
The role of guanyl nucleotide binding proteins in the formation of inositol phosphates in adrenal glomerulosa cells 总被引:3,自引:0,他引:3
P Enyedi I Mucsi L Hunyady K J Catt A Sp?t 《Biochemical and biophysical research communications》1986,140(3):941-947
A non-hydrolysable GTP analogue enhanced the formation of [3H]inositol polyphosphates in permeabilized adrenal glomerulosa cells. Pertussis toxin, which ADP-ribosylated Ni, failed to influence angiotensin-induced formation of 3H-labelled inositol phosphates and the incorporation of [32F]phosphate into phosphatidylinositol and phosphatidic acid. These results show that Ni is present and a G-protein activates phospholipase C also in glomerulosa cells, however, it is not Ni which couples angiotensin receptors to the enzyme. 相似文献
20.
Data are presented on the aboveground and underground biomass of the speciesMarsilea quadrifolia and on the water regime and soil conditions in a habitat of this species in Central Europe (Czechoslovakia). 相似文献