全文获取类型
收费全文 | 1381篇 |
免费 | 96篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 35篇 |
妇产科学 | 29篇 |
基础医学 | 188篇 |
口腔科学 | 204篇 |
临床医学 | 158篇 |
内科学 | 225篇 |
皮肤病学 | 15篇 |
神经病学 | 95篇 |
特种医学 | 54篇 |
外科学 | 196篇 |
综合类 | 7篇 |
一般理论 | 2篇 |
预防医学 | 75篇 |
眼科学 | 1篇 |
药学 | 99篇 |
肿瘤学 | 84篇 |
出版年
2023年 | 10篇 |
2022年 | 13篇 |
2021年 | 27篇 |
2020年 | 23篇 |
2019年 | 28篇 |
2018年 | 33篇 |
2017年 | 32篇 |
2016年 | 43篇 |
2015年 | 25篇 |
2014年 | 45篇 |
2013年 | 85篇 |
2012年 | 83篇 |
2011年 | 88篇 |
2010年 | 55篇 |
2009年 | 40篇 |
2008年 | 71篇 |
2007年 | 82篇 |
2006年 | 79篇 |
2005年 | 72篇 |
2004年 | 51篇 |
2003年 | 62篇 |
2002年 | 54篇 |
2001年 | 28篇 |
2000年 | 28篇 |
1999年 | 35篇 |
1998年 | 20篇 |
1997年 | 14篇 |
1996年 | 14篇 |
1995年 | 12篇 |
1993年 | 6篇 |
1992年 | 13篇 |
1991年 | 17篇 |
1990年 | 11篇 |
1989年 | 19篇 |
1988年 | 10篇 |
1987年 | 14篇 |
1986年 | 18篇 |
1985年 | 22篇 |
1984年 | 11篇 |
1983年 | 15篇 |
1982年 | 9篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1977年 | 11篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1970年 | 3篇 |
1965年 | 3篇 |
排序方式: 共有1479条查询结果,搜索用时 15 毫秒
1.
2.
32nd Annual Meeting of the Scandinavian Society for Psychopharmacology Copenhagen, Denmark April 10–12, 1991 Abstracts 相似文献
3.
Catarina Gonzalez da Silva Karl Magnus Petersson Luís Faísca Martin Ingvar Alexandra Reis 《Journal of clinical and experimental neuropsychology》2004,26(2):266-277
Semantic verbal fluency tasks are commonly used in neuropsychological assessment. Investigations of the influence of level of literacy have not yielded consistent results in the literature. This prompted us to investigate the ecological relevance of task specifics, in particular, the choice of semantic criteria used. Two groups of literate and illiterate subjects were compared on two verbal fluency tasks using different semantic criteria. The performance on a food criterion (supermarket fluency task), considered more ecologically relevant for the two literacy groups, and an animal criterion (animal fluency task) were compared. The data were analysed using both quantitative and qualitative measures. The quantitative analysis indicated that the two literacy groups performed equally well on the supermarket fluency task. In contrast, results differed significantly during the animal fluency task. The qualitative analyses indicated differences between groups related to the strategies used, especially with respect to the animal fluency task. The overall results suggest that there is not a substantial difference between literate and illiterate subjects related to the fundamental workings of semantic memory. However, there is indication that the content of semantic memory reflects differences in shared cultural background--in other words, formal education--, as indicated by the significant interaction between level of literacy and semantic criterion. 相似文献
4.
Nitric oxide-donating properties of mesoionic 3-aryl substituted oxatriazole-5-imine derivatives. 总被引:2,自引:2,他引:0
下载免费PDF全文
![点击此处可从《British journal of pharmacology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
H. Kankaanranta E. Rydell A. S. Petersson P. Holm E. Moilanen T. Corell G. Karup P. Vuorinen S. B. Pedersen A. Wennmalm T. Mets-Ketel 《British journal of pharmacology》1996,117(3):401-406
1. The nitric oxide (NO)-releasing properties of two new mesoionic 3-aryl substituted oxatriazole-5-imine derivatives (GEA 3162 and GEA 3175) were characterized and compared with the known NO-donors 3-morpholino-sydnonimine (SIN-1) and S-nitroso-N-acetylpenicillamine (SNAP). 2. GEA 3162, GEA 3175, SIN-1 and SNAP inhibited adenosine 5'-diphosphate-induced platelet aggregation (IC50 values 0.18, 0.39, 3.73 and 2.12 microM, respectively). All four compounds induced a dose-dependent and more than 4 fold increase in cyclic GMP in platelets. The increase in cyclic GMP concentration was potentiated more than 1.5 fold by a phosphodiesterase inhibitor, zaprinast (10 microM) and inhibited 38-97% by oxyhaemoglobin (10-45 microM). 3. All of the four compounds studied converted oxyhaemoglobin to methaemoglobin and formed a paramagnetic NO-haemoglobin complex. All but GEA 3175 formed nitrite and nitrate in phosphate buffer. During a 40 min incubation, GEA 3162, SIN-1 and SNAP (100 microM) produced 50-70 microM NO2- + NO3- as determined by high performance liquid chromatography. The release of NO and NO2 by GEA 3175 was increased 140 fold in the presence of human plasma (0.14 and 19.7 ppb in the absence and presence of 1% human plasma, respectively) as analyzed by ozone chemiluminescence. 4. The results suggest that the mesoionic 3-aryl substituted oxatriazole-5-imine derivatives GEA 3162 and GEA 3175 as well as SIN-1 and SNAP release nitric oxide. 相似文献
5.
Relation between tobacco use and urinary excretion of thromboxane A2 and prostacyclin metabolites in young men 总被引:1,自引:0,他引:1
A Wennmalm G Benthin E F Granstr?m L Persson A S Petersson S Winell 《Circulation》1991,83(5):1698-1704
BACKGROUND. Cigarette smoking is a risk factor for cardiovascular disease. The present study addressed the effect of tobacco use on the formation of two eicosanoids, thromboxane A2 and prostacyclin, which have been implicated in both acute and chronic cardiovascular disorders. METHODS AND RESULTS. In 577 randomly sampled 18-19-year-old men, the urinary excretion of the 2,3-dinor metabolites of thromboxane A2 and prostacyclin (Tx-M and PGI-M, respectively) was analyzed and related to the subjects' self-reported use of tobacco. Sixty-five percent of the subjects used no tobacco, 7.5% were cigarette smokers, 22% used wet (oral) snuff, and the rest reported a mixed use of tobacco. The urinary excretion of Tx-M was higher (p less than 0.001) in cigarette smokers than in those not using tobacco (180 versus 128 pg/mg creatinine) and was correlated (r = 0.35, p less than 0.05) with the daily cigarette consumption. Snuff users had no increase in their urinary excretion of Tx-M, despite urinary cotinine levels comparable to those in the cigarette smokers (1,210 and 1,560 ng/ml, respectively). The excretion of PGI-M did not differ between non-tobacco users, cigarette smokers, and snuff users. CONCLUSIONS. We conclude that cigarette smoking, but not the use of snuff, facilitates the formation of thromboxane A2. We propose that such an increased formation reflects platelet activation in the absence of vascular injury and that it may be of significance for the subsequent development of cardiovascular disease. 相似文献
6.
Sumei Ren Paul McNamara Pernilla Royster Jae Lee Surinderjit S. Saluja David Koharski Sharon Hendershot Van Truong 《Journal of labelled compounds & radiopharmaceuticals》2007,50(7):643-648
1‐Benzyl‐4‐hydroxy[2‐14C]piperidine, a useful intermediate in labeled compound synthesis, was prepared from [14C]formaldehyde in high yield. The distribution pattern of 14C in the product is consistent with a mechanism involving reversible iminium ion formation and rapid equilibration of the iminium ion through a cationic aza‐Cope rearrangement. These steps precede the rate‐determining intramolecular cyclization step. SCH 351125 is a potent, selective CCR5 receptor antagonist with potential as a treatment for HIV infection. [14C]SCH 351125, required for metabolism studies, was prepared from 1‐benzyl‐4‐hydroxy[2‐14C]piperidine in six steps. [14C]SCH 351125 is a mixture of four atropisomers. Preparation of [14C]SCH 351125 besylate salt of the desired atropisomer pair is also described. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
7.
Clinical History, Skin Prick Test and RAST in the Diagnosis of Birch and Timothy Pollinosis 总被引:2,自引:2,他引:0
The diagnostic efficacy of clinical history (CH), skin prick test (SPT) and RAST was estimated in relation to nasal and conjunctival provocation tests (NPT, CPT) in 69 patients with seasonal rhinoconjunctivitis. The extracts used were freeze-dried, and biologically standardized birch and timothy allergen preparations matched to the extracts on Phadebas RAST discs. Based on single determinations the sensitivity, specificity and predictive values were calculated. There were highly significant (P less than 0.001) correlations between all parameters: NPT, CPT, CH, SPT and RAST. For birch the combination of SPT and RAST made the PTs superfluous as both sensitivity and specificity then reached 100%. With timothy the sensitivity was 97% and with the addition of CH 100%. However, the specificity was only 79% through combining CH, SPT and RAST. The present study using the same standardized allergen preparation in all tests showed a good correlation between indirect test results and provocation tests. 相似文献
8.
BACKGROUND: An open access technique might reduce severe vascular and visceral injuries. An open access technique through the umbilical cicatrix tube has been developed as a routine method with the goal to be easy, safe and used by all surgeons in patients without a previous midline incision. AIM: To evaluate the open technique in a prospective study in 100 consecutive laparoscopic operations regarding time for entrance, surgeons experience and BMI of the patients. METHODS: A midline incision from the linea alba up into the inverted umbilicus was performed in the cicatrix tube and the peritoneum was penetrated allowing air to flow into the abdominal cavity followed by a blunt trocar insertion. RESULTS: Time for access was median 93 seconds. Entrance time in patients with BMI >30 (n=18) was 100 sec and with BMI <30 it was 90 sec (p = 0.71). The median time for consultants was 88 sec and for residents 120 sec (p = 0.003). No gas leakage was seen. Prolonged time for access was seen in three patients; two equipment failures and one obese patent. CONCLUSION: The open access technique is applicable in all patients without a former midline incision. It is fast, easy to learn with very few associated problems. 相似文献
9.
Ivana Kawikova Hirokazu Arakawa Maud Petersson Claes-Gran Lfdahl Bengt-Eric Skoogh Jan Ltvall 《European journal of pharmacology》1995,280(3):293-299
The aim of this study was to evaluate the role of thromboxane A2 in bradykinin-induced airflow obstruction in guinea pig in vivo. Airway insufflation pressure (Pi) was measured to assess airflow obstruction and the thromboxane B2 (a stable metabolite of thromboxane A2) concentration in bronchoalvelolar lavage fluid was determined by radioimmunoassay. The animals were pretreated with propranolol (1 mg/kg i.v.) and suxamethonium (5 mg i.v.) prior to bradykinin administration. Bradykinin instillation into the trachea (300 nmol) induced a Pi increase (47.5 ± 8.3 cm H2O versus 23.8 ± 1.5 in sham) and significant thromboxane B2 release into bronchoalveolar lavage fluid (79 ± 19 pg/ml versus 19 ± 6 in sham). A thromboxane synthase inhibitor (OKY-046, 30 mg/kg i.v.; ((E-E)-3-[p(1H-imidazole-1-yl-methyl) phenyl]-2-propenoic acid hydrochloride mono-hydrate)) or a thromboxane A2 receptor antagonist (ICI192,605, 0.5 mg/kg i.v.; (4-(Z)-6-(2-o-chloro-phenyl-4-o-hydroxyphenyl-1,3-dioxan-cis-5-yl)hexenoic acid)) reduced the Pi increase evoked by bradykinin (38.7 ± 3.8 and 40.6 ± 3.8 cm H2O, respectively). OKY-046 abolished the thromboxane B2 release. A platelet-activating factor receptor antagonist, WEB2086 (1 mg/kg i.v.; (3-[4-(chlorophenyl)-9-methyl-6H-thienol [3,2-f][1,2,4]trizolo-[4,3-a][1,4] diazepin-2-yl]1-4-(4-morpholinyl)-1-propanon) did not significantly affect any measured parameter. We conclude that, in guinea pigs, bradykinin-induced airway effects are associated with a local thromboxane A2 release. 相似文献
10.
E. Johansson S. Mnsson R. Wirestam J. Svensson J.S. Petersson K. Golman F. Sthlberg 《Magnetic resonance in medicine》2004,51(3):464-472
Cerebral perfusion was assessed with 13C MRI in a rat model after intravenous injections of the 13C-labeled compound bis-1,1-(hydroxymethyl)-1-13C-cyclopropane-D8 in aqueous solutions hyperpolarized by dynamic nuclear polarization (DNP). Since the tracer acted as a direct signal source, several of the problems associated with techniques based on traditional dynamic susceptibility contrast (DSC) MRI contrast agents were avoided. Maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) were calculated. The MTT was determined to be 2.8 +/- 0.8 sec. However, arterial partial-volume effects in the animal model prevented accurate absolute quantification of CBF and CBV. It was demonstrated that depolarization of the hyperpolarized 13C tracer via relaxation and the imaging sequence had little influence on CBF assessment when the time resolution of the imaging sequence was short compared to the MTT. However, CBV and MTT were increasingly underestimated as MTT or the depolarization rate increased if depolarization was not taken into account. With a modified bolus-tracking theory depolarization could be compensated for, assuming that the depolarization rate was known. Three separate compensation methods were investigated experimentally and by numerical simulations. 相似文献