全文获取类型
收费全文 | 19416篇 |
免费 | 975篇 |
国内免费 | 55篇 |
专业分类
耳鼻咽喉 | 264篇 |
儿科学 | 520篇 |
妇产科学 | 271篇 |
基础医学 | 2802篇 |
口腔科学 | 881篇 |
临床医学 | 1416篇 |
内科学 | 4180篇 |
皮肤病学 | 369篇 |
神经病学 | 1787篇 |
特种医学 | 537篇 |
外国民族医学 | 2篇 |
外科学 | 2609篇 |
综合类 | 62篇 |
一般理论 | 4篇 |
预防医学 | 1714篇 |
眼科学 | 410篇 |
药学 | 1281篇 |
中国医学 | 62篇 |
肿瘤学 | 1275篇 |
出版年
2023年 | 147篇 |
2022年 | 108篇 |
2021年 | 312篇 |
2020年 | 224篇 |
2019年 | 298篇 |
2018年 | 725篇 |
2017年 | 475篇 |
2016年 | 478篇 |
2015年 | 620篇 |
2014年 | 614篇 |
2013年 | 911篇 |
2012年 | 1580篇 |
2011年 | 1625篇 |
2010年 | 816篇 |
2009年 | 561篇 |
2008年 | 1459篇 |
2007年 | 1430篇 |
2006年 | 1370篇 |
2005年 | 1298篇 |
2004年 | 1233篇 |
2003年 | 1092篇 |
2002年 | 1007篇 |
2001年 | 212篇 |
2000年 | 218篇 |
1999年 | 180篇 |
1998年 | 73篇 |
1997年 | 61篇 |
1996年 | 49篇 |
1995年 | 50篇 |
1994年 | 32篇 |
1993年 | 40篇 |
1992年 | 102篇 |
1991年 | 89篇 |
1990年 | 80篇 |
1989年 | 65篇 |
1988年 | 46篇 |
1987年 | 51篇 |
1986年 | 54篇 |
1985年 | 54篇 |
1984年 | 63篇 |
1983年 | 43篇 |
1982年 | 53篇 |
1981年 | 32篇 |
1980年 | 43篇 |
1979年 | 37篇 |
1978年 | 31篇 |
1977年 | 22篇 |
1976年 | 31篇 |
1973年 | 30篇 |
1971年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 52 毫秒
91.
Many healthy foods are derived from wheat germ. The molecular composition of these products, however, greatly differs as shown by normal-phase HPLC-mass spectrometry analysis; thus, experimental data obtained by one of them is not necessarily true for the other. Avemar is a nontoxic wheat germ extract registered as a special nutriment for cancer patients in Hungary. It shows potent anticancer activity on cell lines by deeply interfering with glucose metabolism and affecting expressions of several kinases. In in vivo experimental models, Avemar is also effective by enhancing the activity of the immune system such as stimulating NK cell activity (by reducing MHC I molecule expression), enhancing TNF secretion of the macrophages, increasing ICAM 1 molecule expression on the vascular endothelial cells. All of these lead to apoptosis of tumor cells. The wide range of biological activity of Avemar probably cannot be explained by only one active ingredient. Since there are numerous experimental data and the clinical benefit repeatedly confirmed Avemar can be one of the most potent and best researched food supplements available for cancer patients. 相似文献
92.
93.
Marcos André C. Bezerra Magnun N.N. Santos Aderson S. Araújo Yara M. Gomes Frederico G.C. Abath 《Hemoglobin》2013,37(1):83-88
Various factors have been described as phenotypic modulators of sickle cell disease, such as levels of fetal hemoglobin (Hb F), presence of α-thalassemia (thal), and haplotypes of the β-globin genes. In order to characterize and determine the frequency of the βS and βC mutations and the prevalence of ?α3.7-thal, 74 patients with sickle cell disease detected during neonatal screening in the State of Pernambuco, Brazil, were studied. The haplotypes of the β gene and ?α3.7-thal were determined using polymerase chain reaction (PCR), and specific restriction endonucleases were used to establish the polymorphic sites of the haplotypes. The results showed the high frequency of the Central African Republic (CAR) or Bantu haplotype in the State of Pernambuco, Brazil. The low frequency of the Benin haplotype recorded in this study, in comparison with other states in northeast Brazil, suggests the diversity of origins of Afro-Brazilians in this region. 相似文献
94.
AndrÉ M. Weitzenhoffer 《The International journal of clinical and experimental hypnosis》2013,61(3):165-177
An attempt was made to confirm the previously reported finding of Hammer and Arkins (1964) of a significantly greater improvement in hypnotic performance as a result of 11 cps intermittent photic stimulation than with frequencies outside the range of EEG alpha activity. Using the Brain Wave Synchronizer, three groups of Ss were given stimulation at 5 cps, 11 cps, and 30 cps. Tests of hypnotic performance were made during stimulation, immediately after stimulation, and a week or more later. No evidence of frequency-specific effect was obtained, and the original finding was considered not confirmed. 相似文献
95.
Santiago Gascon Michael P Leiter Eva Andrés Miguel A Santed Joao P Pereira María J Cunha Agustín Albesa Jesus Montero‐Marín Javier García‐Campayo Begoña Martínez‐Jarreta 《Journal of clinical nursing》2013,22(21-22):3120-3129
Aims and objectives. To examine the prevalence of aggression against healthcare professionals and to determine the possible impact that violent episodes have on healthcare professionals in terms of loss of enthusiasm and involvement towards work. The objective was to analyse the percentage of occupational assault against professionals’ aggression in different types of healthcare services, differentiating between physical and verbal aggression as a possible variable in detecting burnout in doctors and nursing professionals. Background. Leiter and Maslach have explored a double process model of burnout not only based on exhaustion by overload, but also based on personal and organisational value conflicts (community, rewards or values). Moreover, Whittington has obtained conclusive results about the possible relationship between violence and burnout in mental health nurses. Design. A retrospective study was performed in three hospitals and 22 primary care centres in Spain (n = 1·826). Methods. Through different questionnaires, we have explored the relationship between aggression suffered by healthcare workers and burnout. Results. Eleven percent of respondents had been physically assaulted on at least one occasion, whilst 34·4% had suffered threats and intimidation on at least one occasion and 36·6% had been subjected to insults. Both forms of violence, physical and non‐physical aggression, showed significant correlations with symptoms of burnout (emotional exhaustion, depersonalisation and inefficacy). Conclusions. The survey showed evidence of a double process: (1) by which excess workload helps predict burnout, and (2) by which a mismatch in the congruence of values, or interpersonal conflict, contributes in a meaningful way to each of the dimensions of burnout, adding overhead to the process of exhaustion–cynicism–lack of realisation. Relevance to clinical practice. Studies indicate that health professionals are some of the most exposed to disorders steaming from psychosocial risks and a high comorbidity: anxiety, depression, etc. There is a clear need for accurate instruments of evaluation to detect not only the burnout but also the areas that cause it. Professional exhaustion caused by aggression or other factors can reflect a deterioration in the healthcare relationship. 相似文献
96.
Tamashiro A Miceli MH Rando C Tamashiro GA Villegas MO Dini AE Balestrin AE Diaz JA 《Cardiovascular and interventional radiology》2008,31(3):633-637
The objective of this paper is to present an alternative therapeutic approach for the treatment of patients with massive hemoptysis
in whom bronchial and/or nonbronchial systemic arterial embolization is not possible. We describe a percutaneous procedure
for pulmonary segmental artery embolization. Between May 2000 and July 2006, 27 adult patients with hemoptysis underwent percutaneous
treatment at our department; 20 of 27 patients were embolized via bronchial and or nonbronchial systemic arteries and 7 patients
were embolized via pulmonary artery. Femoral arterial access for systemic artery catheterization and femoral vein access for
pulmonary arterial catheterization were used. Gelfoam particles and coils were used for embolization. In this study, we report
on three cases of massive hemoptysis from a systemic arterial source in whom bronchial and/or nonbronchial arteries embolization
was not possible. Percutaneous embolization via the pulmonary artery access was successful in all three patients. In conclusion,
embolization via pulmonary artery is presented as an alternative approach for the management of hemoptysis in patients in
whom bronchial arterial embolization is not possible. 相似文献
97.
Jimenez C Mathieu J Peinnequin A Carter R Alonso A Melin B 《Aviation, space, and environmental medicine》2008,79(6):570-576
INTRODUCTION: As exercise while wearing protective clothing exacerbates body heat storage compared to exercise in the heat, and as exercise alters immune responses, it appeared worthwhile to examine immune and stress responses while wearing protective clothing during moderate exercise. METHODS: Eight subjects completed two bouts of exercise at 45% Vo2(max) in a thermoneutral environment: once while wearing shorts only (Control trial, CON) and again while wearing protective clothing (PRO). Venous blood samples were taken to analyze TNF-alpha mRNA by RT-PCR in LPS stimulated blood, plasma catecholamines, and cortisol. Blood cell count was analyzed by flow cytometry. Rectal temperature (T(re)) was monitored continuously. RESULTS: Exercise with PRO resulted in significantly greater increases in T(re) (39.2 +/- 0.2 degrees C in PRO vs. 38.0 +/- 0.1 degrees C in CON) and plasma epinephrine and norepinephrine (+70% and 150%, respectively). Plasma cortisol increased only at the end of PRO exercise (+33%). Leukocyte and lymphocyte cell count was 14% and 18% higher, respectively, but there were no significant changes in T cytotoxic and NK cell counts compared to the CON trial. Only T helper lymphocyte count was lower (-29%). During both exercise trials, T helper lymphocytes were significantly decreased at the end of exercise and recovery. With or without protective clothing, exercise was associated with an inhibition of TNF- alpha expression in stimulated monocytes (approximately -50% at min 20 and 40, and approximately -30% at min 60). DISCUSSION: Protective clothing wearing induces significant thermal challenge during exercise. The inhibition of TNF-alpha appears to be mediated primarily by exercise and not the added thermal load associated with protective clothing. 相似文献
98.
One important mechanism whereby obesity-associated insulin resistance leads to VLDL overproduction is thought to be by the increased flux of free fatty acids (FFAs) from extrahepatic tissues to liver, which arises as a direct consequence of impaired insulin action in adipose tissue and skeletal muscle. The aim of the present study was to address whether direct measures of peripheral tissue insulin sensitivity with regard to FFAs and glucose in the fasting state are good predictors of postabsorptive VLDL triglyceride secretion rate (VLDL-TG ASR) in humans, independent of obesity. Eighteen healthy control subjects, after an overnight fast, underwent three studies 3 weeks apart, in random order. Study 1: VLDL-TG levels, fractional clearance rate (per h), and VLDL-TG ASR were determined after an intravenous bolus of [1,1,2,3,3-(2)H(5)] glycerol. Study 2: Insulin sensitivity (S(I)), acute insulin response (AIR), and acute C-peptide response to glucose were assessed by frequently sampled intravenous glucose tolerance test using the minimal model approach. Study 3: Insulin-mediated suppression of plasma FFAs (k) and insulin clearance were assessed in response to a low-dose stepwise intravenous insulin infusion. BMI (R(2) = 0.54), AIR, and fasting insulin levels were positively and S(I) negatively correlated with VLDL-TG ASR, but there was no significant association with plasma FFAs or k. Only BMI remained significantly associated with VLDL-TG ASR in multivariate analysis. The best multivariate model for VLDL-TG ASR (R(2) = 0.61, P = 0.0008) included BMI (P = 0.0008) and S(I) (P = 0.12, inversely correlated). VLDL-TG secretion is predicted by BMI, independently of direct measures of insulin sensitivity. The sensitivity to insulin's acute suppressive effect on plasma FFA levels during fasting is not an important determinant of postabsorptive VLDL-TG secretion in humans. 相似文献
99.
Mechanisms of desflurane-induced preconditioning in isolated human right atria in vitro 总被引:12,自引:0,他引:12
Hanouz JL Yvon A Massetti M Lepage O Babatasi G Khayat A Bricard H Gérard JL 《Anesthesiology》2002,97(1):33-41
BACKGROUND: The authors examined the role of adenosine triphosphate-sensitive potassium (K(ATP)) channels, adenosine A1 receptor, and alpha and beta adrenoceptors in desflurane-induced preconditioning in human myocardium, in vitro. METHODS: The authors recorded isometric contraction of human right atrial trabeculae suspended in oxygenated Tyrode's solution (34 degrees C; stimulation frequency, 1 Hz). Before a 30-min anoxic period, 3, 6, and 9% desflurane was administered during 15 min. Desflurane, 6%, was also administered in the presence of 10 microm glibenclamide, a K(ATP) channels antagonist; 10 microm HMR 1098, a sarcolemmal K(ATP) channel antagonist; 800 microm 5-hydroxy-decanoate (5-HD), a mitochondrial K(ATP) channel antagonist; 1 microm phentolamine, an alpha-adrenoceptor antagonist; 1 microm propranolol, a beta-adrenoceptor antagonist; and 100 nm 8-cyclopentyl-1,3-dipropylxanthine (DPX), the adenosine A1 receptor antagonist. Developed force at the end of a 60-min reoxygenation period was compared (mean +/- SD). RESULTS: Desflurane at 3% (95 +/- 13% of baseline), 6% (86 +/- 6% of baseline), and 9% (82 +/- 6% of baseline) enhanced the recovery of force after 60 min of reoxygenation as compared with the control group (50 +/- 11% of baseline). Glibenclamide (60 +/- 12% of baseline), 5-HD (57 +/- 21% of baseline), DPX (63 +/- 19% of baseline), phentolamine (56 +/- 20% of baseline), and propranolol (63 +/- 13% of baseline) abolished desflurane-induced preconditioning. In contrast, HMR 1098 (85 +/- 12% of baseline) did not modify desflurane-induced preconditioning. CONCLUSIONS: In vitro, desflurane preconditions human myocardium against simulated ischemia through activation of mitochondrial K(ATP) channels, adenosine A1 receptor, and alpha and beta adrenoceptors. 相似文献
100.
Le Tourneau T Vincentelli A Fayad G Savoye C Fabre OH Prat A Warembourg H 《The Annals of thoracic surgery》2002,74(6):1869-2015
BACKGROUND: There are little comparative data on Carpentier-Edwards supraannular and pericardial second-generation bioprostheses. The aim of this work was to compare their hemodynamic and clinical outcomes in patients with aortic stenosis. METHODS: We conducted a retrospective study including 150 patients operated on for aortic stenosis between 1989 and 1993. Patients undergoing aortic valve replacement with either a Carpentier-Edwards supraannular or pericardial prosthesis were matched for sex (49% male), age (72 +/- 8 years), body surface area, valve size, associated procedures, and left ventricular ejection fraction. RESULTS: Mean follow-up was 6.5 +/- 3.3 years, giving a total follow-up of 983 patient-years. Thirty-day mortality and 10-year actuarial survival were, respectively, 8% and 51% in the supraannular group and 6.7% and 43.4% in the pericardial group. At 10 years, freedom from thromboembolism, structural failure, and all valve-related events were, respectively, 88.7%, 88.9%, and 68.7% in the supraannular group and 85%, 100%, and 82.2% in the pericardial group. There were four (5.3%) structural failures, and four (5.3%) reoperations for degeneration (n = 3) and endocarditis (n = 1) in the supraannular group. Freedom from structural dysfunction or reoperation was 87.3% in the supraannular group and 100% (p < 0.05) in the pericardial group. Echocardiographic review of 62 of 76 survivors (81.5%) demonstrated a trend toward a better hemodynamic profile of pericardial valves at the end of follow-up. CONCLUSIONS: Ten years after aortic valve replacement for aortic stenosis, Carpentier-Edwards pericardial prostheses give comparable and probably better results than Carpentier-Edwards supraannular prostheses. 相似文献