全文获取类型
收费全文 | 1008篇 |
免费 | 2篇 |
国内免费 | 2篇 |
专业分类
系统科学 | 13篇 |
理论与方法论 | 5篇 |
现状及发展 | 259篇 |
研究方法 | 100篇 |
综合类 | 569篇 |
自然研究 | 66篇 |
出版年
2018年 | 4篇 |
2016年 | 4篇 |
2014年 | 3篇 |
2013年 | 8篇 |
2012年 | 31篇 |
2011年 | 98篇 |
2010年 | 6篇 |
2008年 | 39篇 |
2007年 | 37篇 |
2006年 | 36篇 |
2005年 | 37篇 |
2004年 | 34篇 |
2003年 | 31篇 |
2002年 | 34篇 |
2001年 | 20篇 |
2000年 | 44篇 |
1999年 | 16篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 18篇 |
1991年 | 10篇 |
1990年 | 19篇 |
1989年 | 15篇 |
1988年 | 12篇 |
1987年 | 14篇 |
1986年 | 19篇 |
1985年 | 12篇 |
1984年 | 13篇 |
1983年 | 12篇 |
1982年 | 6篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 16篇 |
1978年 | 19篇 |
1977年 | 20篇 |
1976年 | 15篇 |
1975年 | 20篇 |
1974年 | 23篇 |
1973年 | 17篇 |
1972年 | 20篇 |
1971年 | 31篇 |
1970年 | 44篇 |
1969年 | 15篇 |
1968年 | 27篇 |
1967年 | 26篇 |
1966年 | 22篇 |
1965年 | 10篇 |
1964年 | 8篇 |
1963年 | 2篇 |
1961年 | 2篇 |
排序方式: 共有1012条查询结果,搜索用时 0 毫秒
991.
992.
993.
994.
"Haldane's dilemma" and the rate of evolution 总被引:5,自引:0,他引:5
995.
Distribution of tunichrome and vanadium in sea squirt blood cells sorted by flow cytometry 总被引:1,自引:0,他引:1
E M Oltz S Pollack T Delohery M J Smith M Ojika S Lee K Kustin K Nakanishi 《Experientia》1989,45(2):186-190
Specialized blood cells of many tunicates accumulate high concentrations of vanadium and phenolic peptide pigments called tunichromes (TC). In order to determine whether V and TC reside in the same cells, Ascidia nigra and Ascidia ceratodes blood cell subpopulations were isolated by fluorescence-activated cell sorting (flow cytometry) and chemically analyzed. V was found in the spherical, green/grey signet ring cells, and to a lesser degree in the mulberry-shaped, yellow/green morula cells (MRs), whereas free TC was detected mainly in MRs. 相似文献
996.
Munroe RJ Bergstrom RA Zheng QY Libby B Smith R John SW Schimenti KJ Browning VL Schimenti JC 《Nature genetics》2000,24(3):318-321
The drive to characterize functions of human genes on a global scale has stimulated interest in large-scale generation of mouse mutants. Conventional germ-cell mutagenesis with N-ethyl-N-nitrosourea (ENU) is compromised by an inability to monitor mutation efficiency, strain and interlocus variation in mutation induction, and extensive husbandry requirements. To overcome these obstacles and develop new methods for generating mouse mutants, we devised protocols to generate germline chimaeric mice from embryonic stem (ES) cells heavily mutagenized with ethylmethanesulphonate (EMS). Germline chimaeras were derived from cultures that underwent a mutation rate of up to 1 in 1,200 at the Hprt locus (encoding hypoxanthine guanine phosphoribosyl transferase). The spectrum of mutations induced by EMS and the frameshift mutagen ICR191 was consistent with that observed in other mammalian cells. Chimaeras derived from ES cells treated with EMS transmitted mutations affecting several processes, including limb development, hair growth, hearing and gametogenesis. This technology affords several advantages over traditional mutagenesis, including the ability to conduct shortened breeding schemes and to screen for mutant phenotypes directly in ES cells or their differentiated derivatives. 相似文献
997.
998.
Mutations in ATP6N1B, encoding a new kidney vacuolar proton pump 116-kD subunit, cause recessive distal renal tubular acidosis with preserved hearing 总被引:10,自引:0,他引:10
Smith AN Skaug J Choate KA Nayir A Bakkaloglu A Ozen S Hulton SA Sanjad SA Al-Sabban EA Lifton RP Scherer SW Karet FE 《Nature genetics》2000,26(1):71-75
The multi-subunit H+-ATPase pump is present at particularly high density on the apical (luminal) surface of -intercalated cells of the cortical collecting duct of the distal nephron, where vectorial proton transport is required for urinary acidification. The complete subunit composition of the apical ATPase, however, has not been fully agreed upon. Functional failure of -intercalated cells results in a group of disorders, the distal renal tubular acidoses (dRTA), whose features include metabolic acidosis accompanied by disturbances of potassium balance, urinary calcium solubility, bone physiology and growth. Mutations in the gene encoding the B-subunit of the apical pump (ATP6B1) cause dRTA accompanied by deafness. We previously localized a gene for dRTA with preserved hearing to 7q33-34 (ref. 4). We report here the identification of this gene, ATP6N1B, which encodes an 840 amino acid novel kidney-specific isoform of ATP6N1A, the 116-kD non-catalytic accessory subunit of the proton pump. Northern-blot analysis demonstrated ATP6N1B expression in kidney but not other main organs. Immunofluorescence studies in human kidney cortex revealed that ATP6N1B localizes almost exclusively to the apical surface of -intercalated cells. We screened nine dRTA kindreds with normal audiometry that linked to the ATP6N1B locus, and identified different homozygous mutations in ATP6N1B in eight. These include nonsense, deletion and splice-site changes, all of which will truncate the protein. Our findings identify a new kidney-specific proton pump 116-kD accessory subunit that is highly expressed in proton-secreting cells in the distal nephron, and illustrate its essential role in normal vectorial acid transport into the urine by the kidney. 相似文献
999.
Warm-coding deficits and aberrant inflammatory pain in mice lacking P2X3 receptors 总被引:25,自引:0,他引:25
Souslova V Cesare P Ding Y Akopian AN Stanfa L Suzuki R Carpenter K Dickenson A Boyce S Hill R Nebenuis-Oosthuizen D Smith AJ Kidd EJ Wood JN 《Nature》2000,407(6807):1015-1017
ATP activates damage-sensing neurons (nociceptors) and can evoke a sensation of pain. The ATP receptor P2X3 is selectively expressed by nociceptors and is one of seven ATP-gated, cation-selective ion channels. Here we demonstrate that ablation of the P2X3 gene results in the loss of rapidly desensitizing ATP-gated cation currents in dorsal root ganglion neurons, and that the responses of nodose ganglion neurons to ATP show altered kinetics and pharmacology resulting from the loss of expression of P2X(2/3) heteromultimers. Null mutants have normal sensorimotor function. Behavioural responses to noxious mechanical and thermal stimuli are also normal, although formalin-induced pain behaviour is reduced. In contrast, deletion of the P2X3 receptor causes enhanced thermal hyperalgesia in chronic inflammation. Notably, although dorsal-horn neuronal responses to mechanical and noxious heat application are normal, P2X3-null mice are unable to code the intensity of non-noxious 'warming' stimuli. 相似文献
1000.
New histone kinases in nuclei of rat tissues 总被引:2,自引:0,他引:2