全文获取类型
收费全文 | 2242篇 |
免费 | 156篇 |
出版年
2023年 | 4篇 |
2022年 | 25篇 |
2021年 | 30篇 |
2020年 | 16篇 |
2019年 | 33篇 |
2018年 | 60篇 |
2017年 | 42篇 |
2016年 | 80篇 |
2015年 | 112篇 |
2014年 | 96篇 |
2013年 | 161篇 |
2012年 | 196篇 |
2011年 | 190篇 |
2010年 | 121篇 |
2009年 | 112篇 |
2008年 | 148篇 |
2007年 | 129篇 |
2006年 | 107篇 |
2005年 | 109篇 |
2004年 | 122篇 |
2003年 | 103篇 |
2002年 | 121篇 |
2001年 | 13篇 |
2000年 | 9篇 |
1999年 | 4篇 |
1998年 | 22篇 |
1997年 | 14篇 |
1996年 | 17篇 |
1995年 | 15篇 |
1994年 | 12篇 |
1993年 | 17篇 |
1992年 | 18篇 |
1991年 | 12篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1975年 | 10篇 |
1974年 | 7篇 |
1963年 | 2篇 |
排序方式: 共有2398条查询结果,搜索用时 31 毫秒
31.
Champa Sengupta Vincenzo Deluca David S. Bailey Desh Pal S. Verma 《Plant molecular biology》1981,1(1):19-34
The synthesis and processing of the major storage proteins in soybean cotyledons was studied both in vivo and in vitro. The and subunits of 7S as well as the 11S proteins are synthesized as higher molecular weight-precursors on membrane-bound polysomes. The initial translation products of the 7S are proteolytically cleaved during translation suggesting the removal of a signal peptide as evidenced by the presence of 2 and 2 peptides immunoreactive with 7S antibody in the in vitro chain completion products of the membrane-bound polysomes. This is followed or accompanied by cotranslational glycosylation, which increases their size equivalent to that of initially-synthesized precursors. In vivo pulse-labelled 7S and products are of slightly higher molecular weights than the immunoprecipitable chain-completion products, indicating further post-translational modifications. A slow post-translational processing during a period of 1.5 to 16 h yields the final 7S and glycoproteins.Acidic and basic subunits of the 11S protein appear to be synthesized from common large molecular weight (60K-59K) precursors. Antibodies to the 11S acidic component recognize both acidic and basic domains in the precursor while those raised against basic subunits appear to be specific for that region only. The processing of the 11S precursor is also very slow and occurs post-translationally. This slow rate of processing, coupled with a temporal difference in the synthesis of 7S and 11S components, suggests a highly coordinated mechanism for synthesis and packaging of these proteins into protein bodies during seed development. 相似文献
32.
Natale Cascinelli Gian Paolo Balzarini Vincenzo Fontana Sergio Orefice Umberto Veronesi 《Cancer immunology, immunotherapy : CII》1977,2(3):157-161
Summary From November 1973 to December 1974, 20 patients with advanced malignant melanoma were treated with BCG given by intralymphatic route at the Cancer Institute of Milan. The lyophilized Pasteur BCG was used. Patients were treated with a single dose ranging from 0.2–80 mg. Patients' performance status was never severely impaired.The most frequent side effects were fever, lymphangitis, and lymph node enlargement.Variations were observed in white cell count, ERS and immunoglobulins; in no case did we find evidence of liver toxicity or tumor growth enhancement. It is concluded that the intralymphatic route is a safe way of administrating BCG. 相似文献
33.
34.
35.
Bortolotti U Casarotto D Frugoni C De Mozzi P Thiene G Gallucci V 《Cardiovascular diseases》1981,8(2):250-258
Over a 2-year period, 19 patients whose autologous saphenous veins were either unsuitable or unavailable underwent myocardial revascularization with saphenous vein allografts (SVAs) at our institution. All SVAs had been preserved in 98% glycerol at room temperature for at least 3 weeks (average, 7 weeks); before use, they were rinsed with saline and antibiotic solution. One operative death (5.2%) and three late deaths (16.6%) occurred. Fourteen of the long-term survivors have been observed for 24 to 48 months (average 32.2 months) postoperatively. Nine are asymptomatic, whereas four complain of angina, and one reports exertional dyspnea with-out chest pain. Only three patients have been restudied (7, 10, and 18 months after surgery, respectively); in each of these patients, angiography has shown occlusion of all SVAs. However, histologic examination of glycerol-preserved SVAs has not revealed pathologic changes that would suggest potential graft failure. Despite fairly satisfactory clinical results, preliminary hemodynamic data indicate that glycerol-preserved SVAs are unsuitable for myocardial revascularization in the absence of autologous saphenous veins. 相似文献
36.
Vincenzo Facchini John A. Timbrell 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1980,183(2):167-173
Methods are described for the determination of 4-N-acetylhydrazinophthalazin-1-one, 4-hydrazinophthalazin-1-one, phthalazinone and s-triazolo[3,4-a]phthalazine in human urine.4-Hydrazinophthalazin-1-one and 4-N-acetylhydrazinophthalazin-1-one (following acid hydrolysis) are reacted with acetylacetone to give a distinctive pyrazole derivative which can be determined by gas chromatography using a nitrogen-specific detector.Phthalazinone and s-triazolo[3,4-a]phthalazine are measured underivatised by high-performance liquid chromatography. 相似文献
37.
Vincenzo Panagia Clayton E. Heyliger Patrick C. Choy Naranjan S. Dhalla 《生物化学与生物物理学报:生物膜》1981,640(3)
The influence of a phosphatidylinositol-specific phospholipase C treatment on rat heart sarcolemmal 5′-nucleotidase was investigated. Upon complete hydrolysis of all phosphatidylinositol in the sarcolemma, 75% of 5′-nucleotidase activity was found in the solubilized form. The insolubilized enzyme after this treatment has the same Km for AMP as the untreated, sarcolemmal-bound enzyme (0.04 mM), whereas the solubilized enzyme has a 40-fold increase in Km for AMP (0.16 mM). Other sarcolemmal-bound enzymes were not affected by the same treatment. Hence, the specific involvement of phosphatidylinositol in the binding of 5′-nucleotidase to the sarcolemma of the rat heart is clearly demonstrated. 相似文献
38.
Peter Skrabal Vincenzo Rizzo Antonio Baici Felix Bangerter Pier Luigi Luisi 《Biopolymers》1979,18(4):995-1008
The 1H-nmr spectra of co-oligopeptides of tryptophan and glycine with structure H-Gly-Trp-(Gly)n-Trp-Gly-OH (n = 0–2) and those of several di- and tripeptides have been recorded at 360 MHz with CD3OD solutions containing 0.1N NaOD. The assignment of resonance signals was generally possible by comparing the spectra of structurally related peptides with each other. In order to solve the remaining ambiguities in the assignment, H-(αL,βS)(α,β-d2)Trp-OH, H-Trp-(αL,βS)(α,β-d2)Trp-OH, and H-Trp-(δ1,ε2,ζ2,ζ3,η2-d5)Trp-OH have been prepared and their spectra compared with those of the undeuterated compounds. The distribution of rotamers around the χ1 and (in two cases) χ2 torsion angles of the side chains has been obtained from the vicinal coupling constants 3J and from the long-range coupling constants 4J. These data and an analysis of the chemical shifts of the Gly-Cα protons suggest that the orientation of the aromatic side chain is influenced by the following order of decreasing interaction with the functional groups at N- and C-side: -NH2 > –NHCO– > –CONH–> –COO?. This rule does not hold for the second Trp residue of di- and tripeptides containing the -Trp-Trp- sequence, which has tentatively been attributed to steric effects. 相似文献
39.
Natale Vincenzo Esposito Maria José Martoni Monica Fabbri Marco 《Sleep and biological rhythms》2006,4(1):72-74
Sleep and Biological Rhythms - The aim of the present work was to validate the reduced version of the Morningness-Eveningness Questionnaire (MEQr) using circadian motor activity as external... 相似文献
40.
Injection of tumor cells in mice more than 30 years ago resulted in the discovery of an epithelial antigen, later defined as a cell adhesion molecule (EpCAM). Although EpCAM has since evoked significant interest as a target in cancer therapy, mechanistic insights on the functions of this glycoprotein have been emerging only very recently. This may have been caused by the multitude of functions attributed to the glycoprotein, its localization at different subcellular sites and complex posttranslational modifications. Here, we review how EpCAM modifies cell–cell contact adhesion strength and tissue plasticity, and how it regulates cell proliferation and differentiation. Major knowledge derived from human diseases will be highlighted: Mutant EpCAM that is absent from the cell surface leads to fatal intestinal abnormalities (congenital tufting enteropathy). EpCAM-mediated cell proliferation in cancer may result from signaling (i) via regulated intramembrane proteolysis and/or (ii) the localization and association with binding partners in specialized membrane microdomains. New insight in EpCAM signaling will help to develop optimized cancer therapies and open new avenues in the field of regenerative medicine. 相似文献