全文获取类型
收费全文 | 290篇 |
免费 | 35篇 |
专业分类
325篇 |
出版年
2021年 | 7篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2016年 | 4篇 |
2015年 | 9篇 |
2014年 | 13篇 |
2013年 | 7篇 |
2012年 | 14篇 |
2011年 | 23篇 |
2010年 | 13篇 |
2009年 | 10篇 |
2008年 | 10篇 |
2007年 | 18篇 |
2006年 | 13篇 |
2005年 | 8篇 |
2004年 | 13篇 |
2003年 | 17篇 |
2002年 | 15篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 6篇 |
1996年 | 2篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1988年 | 5篇 |
1986年 | 3篇 |
1985年 | 11篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1970年 | 4篇 |
1969年 | 4篇 |
1968年 | 2篇 |
1967年 | 4篇 |
1966年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有325条查询结果,搜索用时 15 毫秒
61.
62.
The growth of cotyledons and primary leaves of I-day-old Sinapis alba L. plants were studied under various light conditions and action spectra produced. For both responses blue and red light are most effective and a strong fluence rate dependency can be observed. The red light effect appears to be mediated through phytochrome, that of blue light being due to a separate blue light receptor, although this receptor requires the presence of far-red absorbing phytochrome (Pfr ) in order to be effective. 相似文献
63.
Gad M. Gilad Varda H. Gilad 《Biochemical and biophysical research communications》1980,96(3):1312-1316
We describe a new technique for cytochemical localization of ornithine decarboxylase by the use of a synthesized conjugate of rhodamine bound to α-difluoromethylornithine a suicidal inhibitor of the enzyme. The labelled inhibitor retained its specificity and irreversibility towards ornithine decarboxylase inhibition. Using this technique we have localized the enzyme in specific regions of the developing rat cerebellum. This novel technique may be generally applicable to other enzymes. 相似文献
64.
Ben‐Zion Shilo 《EMBO reports》2010,11(4):243-245
The IHES meeting on Pattern Formation in Morphogenesis covered computational approaches to understanding central developmental processes. Global changes in tissue morphogenesis were attributed to small local asymmetries in protein localization or activity, and the underlying mechanisms for robust patterning of defined signalling pathways were explored. 相似文献
65.
Oliynyk M Samborskyy M Lester JB Mironenko T Scott N Dickens S Haydock SF Leadlay PF 《Nature biotechnology》2007,25(4):447-453
Saccharopolyspora erythraea is used for the industrial-scale production of the antibiotic erythromycin A, derivatives of which play a vital role in medicine. The sequenced chromosome of this soil bacterium comprises 8,212,805 base pairs, predicted to encode 7,264 genes. It is circular, like those of the pathogenic actinomycetes Mycobacterium tuberculosis and Corynebacterium diphtheriae, but unlike the linear chromosomes of the model actinomycete Streptomyces coelicolor A3(2) and the closely related Streptomyces avermitilis. The S. erythraea genome contains at least 25 gene clusters for production of known or predicted secondary metabolites, at least 72 genes predicted to confer resistance to a range of common antibiotic classes and many sets of duplicated genes to support its saprophytic lifestyle. The availability of the genome sequence of S. erythraea will improve insight into its biology and facilitate rational development of strains to generate high-titer producers of clinically important antibiotics. 相似文献
66.
Quantitative methods were developed for the study of the early stages in the interaction of Bdellovibrio bacteriovorus and host bacteria. Attachment measurements were based on the differential filtration of host and parasite. Invasion was measured by estimation of radioactively labeled Bdellovibrio cells remaining attached to the host cells after mechanical agitation. The kinetics of attachment and the final number of Bdellovibrio cells attached were dependent on the multiplicity of the parasite, the composition and pH of the medium, and the incubation temperature. Inhibitors of Bdellovibrio motility, including chelating agents, NaN(3), and low pH, all inhibited attachment, as did anaerobiosis. Ultraviolet-killed host cells retained their competence for attachment of Bdellovibrio cells, whereas heat-killed cells lost it. Invasion was selectively inhibited by inhibitors of protein synthesis, such as streptomycin, puromycin, and chloramphenicol. These antibiotics had no effect on attachment. 相似文献
67.
I M Spitz E J Margalioth Y Yeger Y Livshin E Zylber-Haran S Shilo 《Hormones et métabolisme》1984,16(9):492-497
We have assessed the gonadotropin, TSH and PRL responses to the non aromatizable androgens, mesterolone and fluoxymestrone, in 27 patients with primary testicular failure. All patients were given a bolus of LHRH (100 micrograms) and TRH (200 micrograms) at zero time. Nine subjects received a further bolus of TRH at 30 mins. The latter were then given mesterolone 150 mg daily for 6 weeks. The remaining subjects received fluoxymesterone 5 mg daily for 4 weeks and 10 mg daily for 2 weeks. On the last day of the androgen administration, the subjects were re-challenged with LHRH and TRH according to the identical protocol. When compared to controls, the patients had normal circulating levels of testosterone, estradiol, PRL and thyroid hormones. However, basal LH, FSH and TSH levels, as well as gonadotropin responses to LHRH and TSH and PRL responses to TRH, were increased. Mesterolone administration produced no changes in steroids, thyroid hormones, gonadotropins nor PRL. There was, however, a reduction in the integrated and incremental TSH secretion after TRH. Fluoxymesterone administration was accompanied by a reduction in thyroid binding globulin (with associated decreases in T3 and increases in T3 resin uptake). The free T4 index was unaltered, which implies that thyroid function was unchanged. In addition, during fluoxymesterone administration, there was a reduction in testosterone, gonadotropins and LH response to LHRH. Basal TSH did not vary, but there was a reduction in the peak and integrated TSH response to TRH. PRL levels were unaltered during fluoxymesterone treatment.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
68.
Photooxidative reactions of c-phycocyanin 总被引:1,自引:0,他引:1
69.
Attenuated vaccines for tropical theileriosis, babesiosis and heartwater: the continuing necessity 总被引:1,自引:0,他引:1
Overwhelming evidence has accumulated of the effectiveness of immunization with live attenuated vaccines to control tick-borne diseases of livestock. Despite several disadvantages, vaccination with live attenuated organisms against tropical theileriosis, babesiosis and possibly heartwater constitutes one of the most cost-effective intervention strategies. Although great advances have been made through genomics and proteomics research, this has not yet translated into effective non-living vaccines. As a result, there is a continuing necessity to use available live vaccines in tick and tick-borne disease-control strategies adapted to conditions prevailing in many parts of the world. 相似文献
70.
Assaf Zemach Laju K. Paul Perry Stambolsky Varda Rotter 《Experimental cell research》2009,315(20):3554-3562
The Arabidopsis MBD7 (AtMBD7) - a naturally occurring poly MBD protein - was previously found to be functional in binding methylated-CpG dinucleotides in vitro and localized to highly methylated chromocenters in vivo. Furthermore, AtMBD7 has significantly lower mobility within the nucleus conferred by cooperative activity of its three MBD motifs. Here we show that besides the MBD motifs, AtMBD7 possesses a strong chromatin binding domain located at its C-terminus designated sticky-C (StkC). Mutational analysis showed that a glutamic acid residue near the C-terminus is essential though not sufficient for the StkC function. Further analysis demonstrated that this motif can render nuclear proteins highly immobile both in plant and animal cells, without affecting their native subnuclear localization. Thus, the C-terminal, StkC motif plays an important role in fastening AtMBD7 to its chromosomal, CpG-methylated sites. It may be possible to utilize this motif for fastening nuclear proteins to their chromosomal sites both in plant and animal cells for research and gene therapy applications. 相似文献