全文获取类型
收费全文 | 7318篇 |
免费 | 574篇 |
国内免费 | 15篇 |
出版年
2021年 | 98篇 |
2020年 | 58篇 |
2019年 | 77篇 |
2018年 | 81篇 |
2017年 | 82篇 |
2016年 | 200篇 |
2015年 | 291篇 |
2014年 | 327篇 |
2013年 | 400篇 |
2012年 | 471篇 |
2011年 | 471篇 |
2010年 | 320篇 |
2009年 | 264篇 |
2008年 | 397篇 |
2007年 | 356篇 |
2006年 | 365篇 |
2005年 | 340篇 |
2004年 | 301篇 |
2003年 | 333篇 |
2002年 | 304篇 |
2001年 | 88篇 |
2000年 | 68篇 |
1999年 | 71篇 |
1998年 | 67篇 |
1997年 | 69篇 |
1996年 | 46篇 |
1995年 | 48篇 |
1994年 | 62篇 |
1993年 | 57篇 |
1992年 | 75篇 |
1991年 | 60篇 |
1990年 | 54篇 |
1989年 | 50篇 |
1988年 | 48篇 |
1987年 | 45篇 |
1986年 | 31篇 |
1985年 | 41篇 |
1984年 | 69篇 |
1983年 | 48篇 |
1982年 | 60篇 |
1981年 | 67篇 |
1980年 | 66篇 |
1979年 | 44篇 |
1978年 | 68篇 |
1977年 | 53篇 |
1976年 | 49篇 |
1975年 | 42篇 |
1974年 | 36篇 |
1973年 | 50篇 |
1972年 | 37篇 |
排序方式: 共有7907条查询结果,搜索用时 171 毫秒
31.
32.
Mansoor N. Saleh Albert F. LoBuglio Richard H. Wheeler Kimberly J. Rogers Amy Haynes Jeannette Y. Lee M. B. Khazaeli 《Cancer immunology, immunotherapy : CII》1990,32(3):185-190
Summary A group of 15 patients with metastatic colorectal adenocarcinoma received a combination of interferon (0.1 mg/m2, days 1–15) and the murine monoclonal antibody 17-1A (400 mg, days 5, 7, 9 and 12). The treatment was tolerated with minimal toxicity. Of the 14 evaluable patients, 13 developed human antibody to murine 17-1A, with 11 patients demonstrating antibody to the variable region of 17-1A (anti-idiotype). Antibody to the variable region was inhibited by 17-1A but not by mouse immunoglobulin. Sera from patients with substantial anti-idiotype reactivity were capable of inhibiting the binding of murine 17-1A to antigen expressing LS174-T cells thus indicating the presence of antibody directed against the 17-1A combining site (mirror-image anti-idiotype). The median survival of the whole group was 56 weeks and there was no correlation between clinical response/survival and the development of anti-idiotype antibody.Supported by the Veterans Administration Medical Center and by Public Health Services grant CA 45 232 from the National Cancer Institute, National Institutes of Health, Department of Health and Human Services 相似文献
33.
Smith J.J.B.; Mitchell B.K.; Rolseth B.M.; Whitehead A.T.; Albert P.J. 《Chemical senses》1990,15(3):253-270
A set of programs is described for the digitization and analysisof electrophysiological recordings in which the nerve impulsesfrom several different cells may be present. Although they weredesigned for analysis of data from insect taste sensilla, theymay be applicable to other multi-unit preparations, and areavailable free from the authors. The programs run on standardMS-DOS compatible microcomputers, using a readily availableanalog-to-digital plug-in board. They are modular,and break the analysis into several stages, each of which maybe applied to many related files of data in a batchmode. Program design stresses the involvement of the user indecisions as to the effectiveness and accuracy of the analysisas it proceeds, as well as ease and efficiency of use. The programsuse many graphics screens in color, and are controlled by keyboard-or mouse-operated menus; however, they can also be controlledby command-line parameters for standard or repetitive input. 相似文献
34.
Basudev Shome Albert F. Parlow Wan-Kyng Liu Hyun S. Nahm Ted Wen Darrell N. Ward 《Journal of Protein Chemistry》1988,7(4):325-339
A collaborative study from two laboratories has been undertaken to re-evaluate the human follitropin -subunit sequence (hFSH), since areas of uncertainty remain in the wake of two earlier reports. The first report was by Shome and Parlow (1974). The second, by Saxena and Rathnam (1976), proposed revisions for sequence not definitively placed in the first study, as well as some differences in other placements. We have re-examined the sequence of the hFSH with more recent methodology. This has led to revision of certain areas of the sequence and resolution of differences between the two earlier proposals. Specifically, an-Ile-Ser- is established at 21–22, Asp at 41, Arg at 44, Lys at 46, and Glu at 111. These were areas of disagreement in the earlier proposals. A definitive placement of the residues around tryptophan-27 has now been obtained by three laboratories. C-terminal heterogeneity was observed with subunits ending at residue 107, 109, or 111. N-terminal heterogeneity has been observed in all preparations examined to date. A significant population of molecules with a proteolytic nick between residues 38–39 is noted. This is very likely an artifact of the collection and processing. The preparations examined in the present studies showed no evidence of residues 112–118 proposed by Saxena and Rathnam. 相似文献
35.
In an attempt to identify invertebrate homologs of Thy-1 antigen, the optic and central nervous tissue of squid was solubilized in deoxycholate and fractionated by lentil lectin affinity chromatography and gel filtration to yield small abundant glycoproteins. Material with biochemical similarities to Thy-1 was found and shown to consist of two glycoproteins that were ultimately purified using monoclonal antibody affinity columns. Both glycoproteins were sequenced to yield sequences of 84 residues for Sgp-1 and 92 residues for Sgp-2. The sequences were analyzed for similarities to Thy-1 and other Ig-related sequences, and Sgp-1 showed some similarities that were > 3 standard deviation units away from mean random scores when tested with the ALIGN program. However, the sequence patterns were not typical of Ig-related domains and the relationship of Sgp-1 to the Ig superfamily remains problematical. Sgp-2 showed no relationship to the Ig superfamily, but similarities to Ly-6 antigen sequences were noted that are in accord with an evolutionary relationship. The similarities included ten Cys residues in each sequence of which eight were matched in the best alignment given by the ALIGN program. Chemical evidence was obtained for glycophospholipid tails at the COOH-termini of Sgp-1 and Sgp-2 as is the case for Thy-1 and Ly-6 antigens.Abbreviations used in this paper GPL
glycophospholipid
- mAb
monoclonal antibody
- SDS-PAGE
sodium dodecyl sulfate-polyacrylamide gel electrophoresis 相似文献
36.
37.
Toxicity was determined for 15 acaricides against a laboratory strain of northern fowl mites,Ornithonyssus sylviarum (Canestrini and Fanzago). Adult females were exposed to residues on filter paper for 24 h. Three organophosphorous compounds (monocrotophos, cythioate, and famphur) were more toxic to the northern fowl mite than was carbaryl, the most commonly used pesticide in the poultry industry. The other tested compounds were less toxic to the mite than was carbaryl. Four of these, not used previously for northern fowl mite control, had low LC50's for northern fowl mites: aldicarb (0.46); pirimiphos-methyl (0.73); exo, exo-2,8-dichloro-4-thiatricyclo [3.2.1.03.6]octane-4-oxide (AI3-63182) (0.87); and diazinon (2.48).This article reports the results of research only. Mention of a pesticide or proprietary product does not constitute an endorsement or a recommendation of its use by U.S.D.A. 相似文献
38.
Application of bromodeoxyuridine incorporation measurements to the determination of cell distribution within the S phase of the cell cycle 总被引:3,自引:0,他引:3
Flow cytofluorimetric measurement of incorporated bromodeoxyuridine, using a double-stained cell population, allows the determination of the distribution of cells along the cell cycle. We have developed a simple computer program for the direct treatment of 64 x 64 channel histograms. This analysis appears to provide interesting data about the distribution of cells in the various phases of the cell cycle, namely the S phase. Two examples have been chosen to illustrate possible fields for the application of such a program. Comparison of two cell lines such as friend murine erythroleukemia cells (MELC) and fibroblasts FR3T3 cells has shown that this analysis can be used for cell-cycle characterization of a given cell line. The program also allows the differential analysis of cell distribution along the cell cycle as a function of a given parameter. This possibility has been applied to study the variation of cell-cycle parameters as a function of the time of induced differentiation of MELC and reveals changes in the distribution of the cells along the various phases of the cell cycle, namely in the S phase. 相似文献
39.
Blastema cell proliferation in vitro: effects of limb amputation on the mitogenic activity of spinal cord extracts 总被引:1,自引:0,他引:1
B Boilly P Albert 《Biology of the cell / under the auspices of the European Cell Biology Organization》1988,62(2):183-187
Primary cultures of mesenchymal cells of axolotl limb blastemas provide a very sensitive in vitro bioassay for studying nerve dependence of newt regeneration. These cells can be stimulated by crude spinal cord extracts of non-amputated animals in a dose-dependent manner up to 60 micrograms protein/ml of culture medium; at this concentration the mitotic index is increased 4-fold. Spinal cord extracts of axolotls 14 days after forelimb amputation (i.e., late bud stage) are more efficient in stimulating blastema cell proliferation (+50%) than extracts of axolotls 7 days after forelimb amputation (i.e., early bud stage) or of axolotls without amputation. In a similar manner, spinal cord extracts of young axolotls 14 days after forelimb amputation, are more stimulatory than older axolotls 14 d after forelimb amputation which regenerate only a very small blastema during the same time. It appears that spinal cord mitogenic activity is enhanced after limb amputation, probably in correlation with blastema cell requirements for limb regeneration. 相似文献
40.
Elicitor-active preparations from the fungal pathogen of bean Colletotrichum lindemuthianum stimulated the accumulation of products characteristic of lipid peroxidation in treated bean tissues. Bean suspension cells treated with crude and purified elicitors accumulated `lipofuscin-like pigment' (LEP) and malondialdehyde. The accumulation of LFP after about 6 h of treatment coincided with the onset of visible browning and production of the bean phytoalexins kievitone, phaseollin, and phaseollinisoflavan. The induction of phytoalexins and accumulation of LFP were also triggered by treatments with generators of activated oxygen species, xanthine:xanthine oxidase and Fe:ethylenediaminedi-o-hydroxyphenylacetic acid. These data suggest that generation of active oxygen species may be involved in lipid peroxidation triggered by elicitors. 相似文献