全文获取类型
收费全文 | 766篇 |
免费 | 88篇 |
出版年
2021年 | 8篇 |
2020年 | 9篇 |
2019年 | 6篇 |
2018年 | 8篇 |
2017年 | 8篇 |
2016年 | 18篇 |
2015年 | 12篇 |
2014年 | 29篇 |
2013年 | 36篇 |
2012年 | 41篇 |
2011年 | 35篇 |
2010年 | 14篇 |
2009年 | 20篇 |
2008年 | 53篇 |
2007年 | 33篇 |
2006年 | 20篇 |
2005年 | 22篇 |
2004年 | 20篇 |
2003年 | 18篇 |
2002年 | 21篇 |
2001年 | 14篇 |
2000年 | 20篇 |
1999年 | 21篇 |
1998年 | 9篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1994年 | 7篇 |
1993年 | 12篇 |
1992年 | 14篇 |
1991年 | 21篇 |
1990年 | 14篇 |
1989年 | 24篇 |
1988年 | 10篇 |
1987年 | 18篇 |
1986年 | 15篇 |
1985年 | 18篇 |
1984年 | 13篇 |
1983年 | 14篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1979年 | 11篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1976年 | 8篇 |
1975年 | 8篇 |
1974年 | 5篇 |
1973年 | 11篇 |
1972年 | 5篇 |
1967年 | 10篇 |
排序方式: 共有854条查询结果,搜索用时 359 毫秒
771.
772.
E J Mylecharane I Spence R P Gregson 《Comp. Biochem. Physiol. C, Comp. Pharmacol. Toxicol.》1984,79(2):395-399
The effects of atraxin, a neurotoxic protein from the venom glands of the funnel-web spider (Atrax robustus), have been studied in anaesthetized monkeys. At doses of 70 and 80 micrograms kg-1 i.v., atraxin caused respiratory disturbances (dyspnoea and apnoea), and profound alterations in heart rate and blood pressure. These doses also caused salivation, lachrymation, skeletal muscle fasciculation and an elevation in body temperature. Concurrent increases in firing were recorded from the phrenic nerve and from respiratory and other skeletal muscles. It is concluded that atraxin produces the same syndrome in primates as that observed with whole milked male funnel-web venom. 相似文献
773.
Biodistribution of the radioprotective drug 35S-labeled 3-amino-2-hydroxypropyl phosphorothioate (WR77913) 总被引:1,自引:0,他引:1
3-Amino-2-hydroxypropyl phosphorothioate (WR77913), a less toxic phosphorothioate radioprotector than WR2721, has been labeled with 35S. The biodistribution of a radioprotective dose of 800 mg/kg was determined in C3H mice bearing RIF-1 tumors as a function of time after intraperitoneal injection and was expressed as percentage injected dose/gram (% ID/g). Levels of 35S in the blood peaked 10 min after injection, and radioactivity in most tissues was highest at 15 min. Label in most tissues declined markedly between 15 and 60 min, but in gut, salivary glands, tumor, and brain, the levels of radioactivity remained quite stable over 1 hr. At 30 min after injection the highest levels of labeled drug were found in submandibular salivary glands, gut, and kidney, with the lowest level in brain. Tumors had approximately the same amount of label as blood, muscle, skin, and esophagus. Two principal differences between the distribution of label from WR77913 and WR2721 were defined. Although blood levels of 35S-WR2721 also peaked 10 min after injection, the 10-min blood levels achieved for WR77913 were more than fourfold greater than those attained by WR2721. Maximum levels of WR2721 occurred in most tissues 30 to 60 min after administration of the drug, compared to 15 min for WR77913. The basis for these differences remains to be determined, but these results suggest that the optimum interval between administration of WR77913 and irradiation may be shorter than for WR2721. 相似文献
774.
Des Spence 《BMJ (Clinical research ed.)》2007,335(7630):1158
775.
Summary From the 15 lochs examined at altitudes between 9 and 267 m in western Sutherland and Wester Ross, a few areas of tall fen (with Hippuris, Sparganium erectum, Osmunda etc.) survive to indicate its potential distribution. Predominant grazed fen comprises patches of short Juncus articulatus and Carex nigra. Reedswamp is scarce, being dominated by Eleocharis palustris, Carex lasiocarpa and Schoenoplectus lacustris and, rarely, by Phragmites and Sparganium erectum. Floating-leaved vegetation was only encountered twice. Submerged vegetation to water depths of at least 1 m consists in the main of sparse Lobelia-Littorella with Juncus bulbosus, typical of the prevailing stony shores in every loch. Extensive Isoetes lacustris meadows may occur beyond that, with Potamogeton praelongus or P. perfoliatus stands in waters of alkalinities over 0·45 m-equiv 1-1, reaching depths of 3 m in Loch Urigill. Loch Urigill is unusual in having dominant Isoetes at a water alkalinity of 0·76 m-equiv 1-1 along with abundant Anabaena species and some Potamogeton filiformis. 相似文献
776.
Tracy M. Rout Stephen M. Jackson Dalene Adam Jacqui Diggins Eve McDonald-Madden Nicola J. Mitchell Terry V. Walshe 《Austral ecology》2023,48(4):803-821
Ex situ (‘off-site’) management refers to keeping species in artificial conditions away from their natural habitat and includes captive breeding facilities, botanical gardens and seed banks. There is scope for ex situ programmes to be more commonly used for supplementing or establishing wild populations. However, undertaking ex situ management comes with risks, costs and uncertainties, which must be assessed in the context of available in situ (‘on-site’) management options. The PACES (Planning and Assessment for Conservation through Ex situ management) tool tailors the principles of structured decision-making to the specific problem of assessing and comparing ex situ and in situ management options. We applied the PACES tool to the mahogany glider (Petaurus gracilis), a threatened arboreal marsupial endemic to north Queensland, Australia. Through an expert elicitation process, we predicted the likely benefits of an ex situ and two in situ management options, as compared to a baseline ‘do-nothing’ scenario. The ‘in situ plus’ alternative (where extra resources are dedicated to in situ management) was predicted to result in the largest population increase according to the participants' best estimates. However, this benefit came at a much larger cost than the ex situ alternative, and without the benefit of an ex situ insurance population. The PACES tool assessment allowed the Mahogany Glider Recovery Team to document and plan the financial costs, risks and benefits of potential future management options for the mahogany glider, laying a transparent basis for future assessment and decision-making. 相似文献
777.
T.C. Peakman C.H. Reynolds M.G. Willson J.D. Moore P. Spence M. Sydenham D.J. Linstead D.R. Gewert M.J. Page 《生物化学与生物物理学报:疾病的分子基础》1992,1138(1):68-74
The cellular gene c-abl is the normal homologue of the transforming gene (v-abl) within the genome of the Abelson leukaemia virus. The cDNA sequence coding for the cellular form of the murine abl gene (c-abl type IV) has been inserted into the baculovirus transfer vector, pAc36C, so that the c-abl gene is under the control of the polyhedrin promoter of Autographa californica nuclear polyhedrosis virus (AcNPV). Spodoptera frugiperda cells infected with the recombinant transfer vector in the presence of wild type AcNPV DNA yielded recombinant, polyhedrin negative virus that expressed moderate levesl of the c-Abl protein (representing approx. 0.5–1% of the stained cellular proteins as determined by densitometric scanning). The insect derived c-Abl protein was compared to the P210-BCR/ABL protein from K562 cells, a cell line derived from a patient with chronic myelogenous leukaemia. Antibodies raised againts synthetic peptides based on c-abl encoded peptides react with the insect derived c-Abl. In addition, the baculovirus derived c-Abl protein has a tyrosine kinase activity as demonstrated by phosphorylation of a synthetic polypeptide and also by autophosphorylation. Phosphoamino acid analysis of immunoprecipitated, autophosphorylated baculovirus derived c-Abl protein indicates that the majority of label incorporated is on the tyrosine residues. Immunofluorescence microscopy has been used to show that the majority of the c-Abl protein expressed in cells infected with recombinant virus is located in the nuclear and plasma membranes. 相似文献
778.
779.
780.
Jacqui H. Todd Robert M. Simpson Joanne Poulton Emma I. Barraclough Kurt Villsen Amber Brooks Kate Richards Dan Jones 《Agricultural and Forest Entomology》2020,22(3):212-223
- The objective of this study was to assess barcoding of environmental DNA as a method for monitoring invertebrate ecosystem service providers in soil samples.
- We selected 26 invertebrate ecosystem service providers that occur in New Zealand kiwifruit or apple orchards and produced mitochondrial cytochrome c oxidase gene subunit I (cytochrome oxidase I) and/or 28S ribosomal DNA sequences for each. Specific barcode primers were designed for each invertebrate ecosystem service provider and tested, along with generic barcoding cytochrome oxidase I primers, for their ability to detect DNA from invertebrate ecosystem service providers that had been added to sterilized and unsterilized soil samples.
- Although the specific primers accurately detected the invertebrate ecosystem service providers in more than 96% of the samples, the generic cytochrome oxidase I primers detected only 37% of the invertebrate ecosystem service providers added to the sterilized samples and 2.5% in the unsterilized samples.
- In a field test, we compared metabarcoding with traditional invertebrate trapping methods to detect the invertebrate ecosystem service providers in 10 kiwifruit and 10 apple orchards. All invertebrate ecosystem service providers were collected in traps in at least one orchard, but very few were identified by metabarcoding of soil environmental DNA.
- Although the specific primers can be used as a tool for monitoring invertebrate ecosystem service providers in soil samples, methodological improvements are needed before metabarcoding of soil environmental DNA can be used to monitor these taxa.