全文获取类型
收费全文 | 7969篇 |
免费 | 778篇 |
国内免费 | 1篇 |
出版年
2023年 | 48篇 |
2022年 | 75篇 |
2021年 | 143篇 |
2020年 | 94篇 |
2019年 | 126篇 |
2018年 | 132篇 |
2017年 | 129篇 |
2016年 | 233篇 |
2015年 | 332篇 |
2014年 | 420篇 |
2013年 | 436篇 |
2012年 | 616篇 |
2011年 | 552篇 |
2010年 | 360篇 |
2009年 | 311篇 |
2008年 | 408篇 |
2007年 | 444篇 |
2006年 | 395篇 |
2005年 | 381篇 |
2004年 | 368篇 |
2003年 | 372篇 |
2002年 | 304篇 |
2001年 | 98篇 |
2000年 | 89篇 |
1999年 | 91篇 |
1998年 | 112篇 |
1997年 | 82篇 |
1996年 | 82篇 |
1995年 | 79篇 |
1994年 | 69篇 |
1993年 | 63篇 |
1992年 | 97篇 |
1991年 | 55篇 |
1990年 | 71篇 |
1989年 | 58篇 |
1988年 | 79篇 |
1987年 | 59篇 |
1986年 | 43篇 |
1985年 | 55篇 |
1984年 | 69篇 |
1983年 | 43篇 |
1982年 | 35篇 |
1981年 | 53篇 |
1980年 | 30篇 |
1979年 | 45篇 |
1978年 | 35篇 |
1977年 | 27篇 |
1976年 | 29篇 |
1974年 | 44篇 |
1970年 | 23篇 |
排序方式: 共有8748条查询结果,搜索用时 250 毫秒
81.
82.
Russell G. Snell Leslie M. Thompson Danilo A. Tagle Tracey L. Holloway Glenn Barnes Helen G. Harley Lodewijk A. Sandkuijl Marcy E. MacDonald Francis S. Collins James F. Gusella Peter S. Harper Duncan J. Shaw 《American journal of human genetics》1992,51(2):357-362
We report both a recombination event that places the Huntington disease gene proximal to the marker D4S98 and an extended linkage-disequilibrium study that uses this marker and confirms the existence of disequilibrium between it and the HD locus. We also report the cloning of other sequences in the region around D4S98, including a new polymorphic marker R10 and conserved sequences that identify a gene in the region of interest. 相似文献
83.
The effect of iron on anaerobic digestion 总被引:1,自引:0,他引:1
Summary The ability of methanogenic bacteria to adapt to high concentrations of iron was investigated using a 9l Upflow Anaerobic Sludge Blanket (UASB) reactor fed semi-continuously with a synthetic waste containing glucose as the organic carbon source. It was found that an iron concentration of up to 5 650 mg/l, which is well in excess of previously reported toxicity levels, had no inhibitory effects on anaerobic digestion, with the exception of a decrease in biogas production. The iron precipitated out and accumulated in the sludge bed of the digester, resulting in very low concentrations of iron in the digester effluent. 相似文献
84.
Felix Gisela; Altmann Thomas; Uwer Ursula; Jessop Alison; Willmitzer Lothar; Morris Peter-Christian 《Journal of experimental botany》1996,47(8):1007-1017
A novel Arabidopsis thaliana (L.) Heynh. developmental mutant,waldmeister (wam), is described. This mutant was found in theprogeny arising from an Ac-Ds tagging experiment, but does notappear to be tagged by an introduced transposon. This recessivenuclear mutation maps between GAPB and ap1 on chromosome 1 andshows extreme morphological and physiological changes in bothfloral and vegetative tissues. Changes to the vegetative phenotypeinclude altered leaf morphology, multiple rosettes, stem fasciation,retarded senescence and disturbed geotropic growth. Changesto the floral phenotype include delayed flowering, increasednumber of inflorescences, determinate inflorescences, alterednumber and morphology of floral organs, chimeric floral organs,and ectopic ovules . wam was crossed to a number of previouslydescribed floral mutants: apetela 2, apetela 3, pistillata,agamous, and leafy. The phenotype of the double mutant was ineach case additive. In the case of agamous, however, the indeterminaterepetitive floral structure of agamous was lacking, emphasizingthe determinate inflorescence growth of wam. The extreme phenotypeof the wam mutant is suggestive of a disturbance to a gene ofglobal importance in the regulation of plant growth and development. Key words: Arabidopsis thaliana, waldmeister, developmental mutant, flower mutant 相似文献
85.
The molecular biology of plant acclimation to low temperature 总被引:51,自引:8,他引:43
86.
Laboratory microcosms were used to: i) measure the effects of soil moisture on survival of Steinernema riobravis and ii) investigate the suitability of using microcosms to study motility and survival of these nematodes. Nematodes recovered from soil contained in petri dishes declined by more than 95% during 7 days, whereas nematodes recovered from the inner surfaces of dishes increased 35-fold. After 7 days in dishes, >20 times as many nematodes were recovered from dish surfaces than from soil. Nematodes exhibited a negative geotropism; greater numbers of nematodes were recovered from the lid surfaces than from the surfaces of dishes. Survivorship of nematodes in soil in plastic centrifuge tubes was somewhat greater than in petri dishes, and fewer nematodes ascended above the soil line in tubes than dishes. Downward migration of nematodes was inversely related to soil column diameter, possibly due to relatively unimpeded movement along container surfaces. An assay was developed by which nematodes were rinsed from the inner surfaces of centrifuge tubes into the soil. The resulting slurry was then processed on Baermann trays to recover motile nematodes. Nematode survival in soil in centrifuge tubes was higher at soil moistures between 2-4% than at lower (0.5-1.0%) and higher (4.0-12.0%) moisture levels. Survival of S. riobravis may be enhanced by quiescence induced by moisture deficits. 相似文献
87.
Christopher M. Hylton Kay Denyer Peter L. Keeling Ming-Tang Chang Alison M. Smith 《Planta》1996,198(2):230-237
The effects of waxy mutations on starch-granule-bound starch synthases (EC 2.4.1.18) in the developing endosperm of barley (Hordeum vulgare L.) and maize (Zea mays L.) have been investigated. Three granule-bound starch synthases in barley endosperm were identified by use of antibodies to known starch synthases, by reconstitution and assay of individual proteins from sodium dodecyl sulphate-polyacrylamide gels of granule-bound proteins, and by partial purification of proteins released by enzymic digestion of starch. These are proteins of 60, 77 and 90 kDa. Use of antibodies to known starch synthases and partial purification of proteins released by enzymic digestion of starch indicated that there may be at least four granule-bound starch synthases in maize endosperm: proteins of 59, 74, 77 and 83 kDa. Mutations at the waxy loci of both species affected only the 60- (barley) and 59-(maize) kDa isoforms. No evidence was found that other putative isoforms are altered in abundance or activity by the mutations. The contribution of our results to understanding of the starch synthase activity of intact starch granules and the mechanism of amylose synthesis is discussed.We are very grateful to Dr. Roger Ellis (SCRI, Dundee, Scotland) for the gift of barley seeds, and to Drs Roger Ellis, Alan Schulman and Cathie Martin for helpful advice and comments during the course of this work. 相似文献
88.
89.
Thomas Altmann Gisela Felix Alison Jessop Annette Kauschmann Ursula Uwer Hugo Peña-Cortés Lothar Willmitzer 《Molecular genetics and genomics : MGG》1995,247(5):646-652
Using a two-component Ac/Ds system consisting of a stabilized Ac element (Acc1) and a non-autonomous element (DsA), 650 families of plants carrying independent germinal DsA excisions/transpositions were isolated. Progenies of 559 of these Acc1/DsA families, together with 43 families of plants selected for excision/transposition of wild-type (wt)Ac, were subjected to a broad screening program for mutants exhibiting visible alterations. This resulted in the identification of 48 mutants showing a wide variety of mutant phenotypes, including embryo lethality (24 mutants), chlorophyll defects (5 mutants), defective seedlings (2 mutants), reduced fertility (5 mutants), reduced size (3 mutants), altered leaf morphology (2 mutants), dark green, unexpanded rosette leaves (3 mutants), and aberrant flower or shoot morphology (4 mutants). To test whether these mutants were due to transposon insertions, a series of Southern blot experiments was performed on 28 families, comparing in each case several mutant plants with others showing the wild-type phenotype. A preliminary analysis revealed in 4 of the 28 families analyzed a common, novel DsA fragment in all mutant plants, which was present only in heterozygous plants with wt phenotype, as expected for DsA insertion mutations. These four mutants included two showing embryo lethality, one with dark green, unexpanded rosette leaves and stunted inflorescences, and one with curly growth of stems, leaves and siliques. Further evidence for DsA insertion mutations was obtained for one embryo lethal mutant and for the stunted mutant, while in case of the second embryo lethal mutant, the DsA insertion could be separated from the mutant locus by genetic recombination. 相似文献
90.