全文获取类型
收费全文 | 222篇 |
免费 | 18篇 |
专业分类
儿科学 | 6篇 |
妇产科学 | 2篇 |
基础医学 | 18篇 |
口腔科学 | 2篇 |
临床医学 | 67篇 |
内科学 | 75篇 |
皮肤病学 | 10篇 |
神经病学 | 7篇 |
外科学 | 19篇 |
预防医学 | 9篇 |
药学 | 25篇 |
出版年
2022年 | 3篇 |
2021年 | 1篇 |
2017年 | 7篇 |
2016年 | 7篇 |
2015年 | 7篇 |
2014年 | 8篇 |
2013年 | 11篇 |
2012年 | 2篇 |
2011年 | 2篇 |
2010年 | 13篇 |
2009年 | 17篇 |
2008年 | 3篇 |
2007年 | 1篇 |
2006年 | 4篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 10篇 |
1997年 | 13篇 |
1996年 | 14篇 |
1995年 | 17篇 |
1994年 | 9篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1959年 | 3篇 |
1958年 | 1篇 |
1957年 | 10篇 |
1956年 | 3篇 |
1955年 | 1篇 |
1954年 | 1篇 |
1937年 | 2篇 |
排序方式: 共有240条查询结果,搜索用时 15 毫秒
101.
GIULIANO SILIGARDI ALEX F. DRAKE PAOLO MASCAGNI DAVID J. ROWLANDS FRED BROWN WILLIAM A. GIBBONS 《Chemical biology & drug design》1991,38(6):519-527
The circular dichroism spectrum of the 20-residue immunogenic peptide from the foot-and-mouth disease virus (VP1; 141-160 of serotype A, subtype 12) was solvent- and temperature-dependent. Careful solvent titration revealed two isodichroic points and plateaux consistent with stepwise unfolding of specific stable conformations. Variable temperature studies in cryogenic solvents and urea perturbation were consistent with the existence of three conformational moieties, the left-handed extended helix, the a-helix, and the α-helix. The number of residues in each helix was confirmed by CD spectral simulations. The strategy described here can be used to determine the components of a conformational equilibrium and their statistical weights, to study peptide folding and unfolding and to determine the bioactive conformation(s) of linear peptides. The conclusions were supported by 2D-NMR studies. A new mechanism for the stabilization of left-handed extended helices and destabilization of a-helices by urea is proposed. The structure of the peptide as resolved by CD spectroscopy is of particular significance since the conformation of this antigenic sequence in situ has so far not been solved by X-ray crystallography. 相似文献
102.
PAOLO ALBONI SALVATORE SCARF GIUSEPPE FUCÁ NELLY PAPARELLA PANAYIU YANNACOPULU 《Pacing and clinical electrophysiology : PACE》1995,18(5):980-985
The hemodynamics of induced atrial fibrillation (AF) was investigated in 15 patients (ages 58 ± 11 years) with paroxysmal AF presenting without organic heart disease or hypertension. A hemodynamic study was performed both during sinus rhythm and after the induction of AF. The mean heart rate increased from 73 ± 11 to 128 ± 18 beats/min (P < 0.001) after AF. Systolic and mean aortic pressures did not significantly change, and diastolic aortic pressure increased (78 ± 11 vs 89 ± 12 mmHg, P < 0.01). Left ventricular enddiastolic pressure decreased during AF (9 ± 3 vs 6 ± 2.6 mmHg, P < 0.005), whereas mean pulmonary wedge pressure increased (8 ± 2 vs 12 ± 4 mmHg, P < 0.001). Systolic pulmonary arterial pressure did not show significant variations, and there was a slight but statistically significant increase in the diastolic and mean pulmonary arterial pressures (P < 0.01). The right ventricular end-diastolic pressure decreased during AF (5.6 ± 2 vs 3.8 ± 2 mmHg, P < 0.01 j, whereas mean right atrial pressure showed a trend toward an increase. Stroke volume markedly decreased (P < 0.001) while the cardiac index did not significantly change. Systemic vascular resistance, pulmonary arteriolar resistance, and the arteriovenous O2 difference showed no significant variations after the induction of AF. These results suggest that in subjects without organic heart disease, paroxysmal AF is well tolerated hemodynamicaily, and the rise in the atrial pressures during AF is not related to an increase in the ventricular end-diastolic pressure. 相似文献
103.
PAOLO RUZZA ANDREA CALDIIRAN BRUNO FILIPPI ARIANNA DONELLA-DEANA LORENZO A. PINNA GIANFRANCO BORIN 《Chemical biology & drug design》1993,41(3):291-299
The transforming gene of Abelson murine leukaemia virus (v-abl) codes for a membrane-associated tyrosine-specific protein kinase (abl TPK). Analysis of the v-abl gene has shown that both the fibroblast-transforming and tyrosine-protein kinase activities reside within a minimal region encoding a protein of 43 kDa (p43v-abl), which represents the most active, isolated form of this enzyme. Since the cellular substrates for p43 v-abl are yet to be identified, we synthesized by classical solution methods the octapeptide H-Gly-Asp-Thr-Tyr-Thr-Ala-His-Ala-OH, corresponding to the structural sequence of the main putative autophosphorylation site (Tyr 515) of the abl TPK, as well as some of its analogs modified in positions -2, -1, + 1 and + 3. The synthetic peptides were tested as substrates for the p43v-abl. The kinetic data obtained indicate that the rates of their phosphorylation vary considerably depending on the sequence of the peptide, as expected. As a rule, no significant increment of the efficiency results from each substitution in the parent sequence. While the replacement of the two charged residues, namely Asp-2 and His-7, with neutral Ala is well tolerated, the substitution with amino acids bearing opposite charges is detrimental. The correlation between secondary structure of our synthetic octapeptides and their substrate recognition by p43v-abl was studied using CD and fluorescence spectroscopy in 5 mM Tris, in 98% TFE/Tris and in 30 mM SDS solutions. The comparison of the spectroscopic data with the kinetic parameters does not confirm a close relationship between the conformational properties of these peptides and their enzymatic role. 相似文献
104.
MARIA G. ENNAS SERGIO LACONI PAOLO E. MANCONI COSTANTINO MARCELLO GIUSEPPINA PARODO PAOLA PULIGHEDDU UMBERTO LECCA 《American journal of reproductive immunology (New York, N.Y. : 1989)》1987,13(3):83-86
ABSTRACT: Eighteen copper intrauterine devices (IUDs), removed after 25 months of use, were examined to evaluate cells adhering to them (IAC). By means of monoclonal antibodies, the antigenic phenotype of IAC was studied, along with some IAC cytochemical properties. Sixty percent of IAC were identified as granulocytes based on morphological, cytochemical, and antigenic characteristics. A small proportion of IAC were shaped like large foreign-body macrophages, with multiple picnotic nuclei, and diffused alpha naphtyl acetate esterase (ANAE) activity. Some IAC identified as macrophages from a morphological view point also showed dipeptidil-diaminopeptidase IV (DAPIV) reactivity, previously described only in T-helper lymphocytes. Most IAC identified as macrophages reacted with the monoclonal antibodies OKM1 and HLA-DR, and showed ANAE activity in the form of small multiple granules. The hypothesis that IUD-adhering macrophages with an ANAE +, DAPIV+, OKM1 +, and HLA-DR + phenotype could play a role in the inactivation of spermatozoa can be proposed. 相似文献
105.
RABAJOLI FILIPPO; ARNEODO DANIELA; BALZOLA FRANCO; LEO LINDA; VINEIS PAOLO 《European journal of public health》1996,6(3):227-230
We have conducted a hospital-based case-control study on 157patients with newly diagnosed myocardial infarction and 157hospital controls. All were men, 3569 years old and non-smokersor ex-smokers of at least 6 months. A clearcut inverse dose-responserelationship was found between alcohol intake (chiefly red wine)and risk of Ml (odds ratios were 0.69, 0.43 and 0.42, for thosedrinking 130, 3090 and >90 drinks per month,compared to <1). Adjustment by coronary risk factors in logistic-regressionmodels increased the strength of the association with alcohol.Protection was somewhat stronger than in studies conducted incountries where the consumption of beer or liquors is heavierthan that of wine. The protective effect might be due to theantioxidant properties of phenolic substances contained in redwine. 相似文献
106.
ENEA MENEGATTI SANTO SCALIA FABRIZIO BORTOLOTTI PAOLO ASCENZI ANTONIO DE MARCO 《Chemical biology & drug design》1989,34(3):161-165
Tryptic digestion of the mouse epidermal growth factor (mEGF) and the chromatographic separation of its proteolytic fragments by RP-HPLC affords the isolation of the pure hormone, of its 1–48 (Des(49–53)mEGF) and 1–45 (Des(46–53)mEGF) derivatives, and of the carboxyl-terminal pentapeptide W49–W50-E51-L52-R53. Kinetics of mEGF proteolytic degradation follows a two-state time-course: native mEGF being converted into Des(49–53)mEGF with an apparent half-time of 10min; and Des(49–53)mEGF subsequently hydrolyzed to Des(46–53)mEGF with an apparent half-time of 7 h. Native mEGF and its proteolytic fragments have been characterized by 1H-n.m.r. spectroscopy. In the aromatic and aliphatic regions, the 1H-n.m.r. spectrum proved to be a sufficiently sensitive probe for following controlled proteolysis, and for analyzing the influence of the carboxyl-terminal sequence on the hormone conformation and stability. 相似文献
107.
108.
PAOLO ONETO GB 《Archivio italiano di urologia》1955,28(2):179-186
109.
110.
Lissoni P Mandala M Rossini F Fumagalli L Barni S 《Hematology (Amsterdam, Netherlands)》1999,4(4):335-343
The recent advances in the psychoneuroimmunology have suggested that the hematopoiesis may be under a neuroendocrine regulation, mainly exerted by the pineal gland. In particular, melatonin (MLT), which is the main pineal hormone, has appeared to stimulate platelet generation, probably by promoting the megakaryocyte fragmentation and modulating the cytokine network involved in platelet production. On this basis, we have evaluated the effect of pharmacological doses of MLT on platelet number in patients with persistent thrombocytopenia due to different causes. The study included 200 patients, who were randomized to receive supportive care alone or MLT at 20 mg/day orally in the evening, for al least 1 month. No MLT-related toxicity occured. Platelet mean number rapidly and significantly increased in response to MLT, and a normalization of platelet number was achieved on MLT therapy in 71/98 (72%) patients. The least responsive form of thrombocytopenia was DIC. This study shows that the pineal hormone MLT may represent a well tolerable and effective therapy of thrombocytopenia due to different pathogenetic mechanisms. 相似文献