全文获取类型
收费全文 | 26901篇 |
免费 | 1783篇 |
国内免费 | 164篇 |
专业分类
耳鼻咽喉 | 276篇 |
儿科学 | 714篇 |
妇产科学 | 780篇 |
基础医学 | 3039篇 |
口腔科学 | 711篇 |
临床医学 | 2417篇 |
内科学 | 5363篇 |
皮肤病学 | 483篇 |
神经病学 | 1340篇 |
特种医学 | 1112篇 |
外国民族医学 | 11篇 |
外科学 | 4486篇 |
综合类 | 506篇 |
现状与发展 | 2篇 |
一般理论 | 12篇 |
预防医学 | 2555篇 |
眼科学 | 649篇 |
药学 | 2413篇 |
中国医学 | 144篇 |
肿瘤学 | 1835篇 |
出版年
2023年 | 303篇 |
2022年 | 835篇 |
2021年 | 1246篇 |
2020年 | 693篇 |
2019年 | 876篇 |
2018年 | 1181篇 |
2017年 | 726篇 |
2016年 | 778篇 |
2015年 | 764篇 |
2014年 | 1095篇 |
2013年 | 1326篇 |
2012年 | 1919篇 |
2011年 | 2056篇 |
2010年 | 1174篇 |
2009年 | 880篇 |
2008年 | 1311篇 |
2007年 | 1347篇 |
2006年 | 1236篇 |
2005年 | 1162篇 |
2004年 | 1051篇 |
2003年 | 965篇 |
2002年 | 901篇 |
2001年 | 408篇 |
2000年 | 401篇 |
1999年 | 305篇 |
1998年 | 169篇 |
1997年 | 152篇 |
1996年 | 140篇 |
1995年 | 153篇 |
1994年 | 130篇 |
1993年 | 116篇 |
1992年 | 234篇 |
1991年 | 228篇 |
1990年 | 212篇 |
1989年 | 188篇 |
1988年 | 220篇 |
1987年 | 186篇 |
1986年 | 146篇 |
1985年 | 168篇 |
1984年 | 140篇 |
1983年 | 132篇 |
1982年 | 91篇 |
1981年 | 70篇 |
1980年 | 57篇 |
1979年 | 104篇 |
1978年 | 83篇 |
1977年 | 61篇 |
1976年 | 64篇 |
1974年 | 75篇 |
1973年 | 86篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Free hydrocortisone, hydrocortisone incorporated into microspheres and empty microspheres have been administered orally to rats with carrageenan-induced hindpaw inflammation. Hydrocortisone administered in particles was effective at a lower dose than free steroid in reducing inflammation. Inflammatory exudates were able to release steroid from the microspheres by proteolytic degradation. 相似文献
52.
Summary It has been suggested that age changes in the morphology of the neuromuscular junction (NMJ) may reflect altered physical activity levels rather than the unique effects of ageing. Additionally, previous studies have indicated that the structure of the NMJ may be modulated with exercise. To investigate these questions, quantitative morphometry was determined on soleus and extensor digitorum longus (EDL) nerve terminals stained with zinc iodide-osmium from C57BL/6NNia mice under control and endurance exercised conditions at 12, 18 and 24 months of age.As previously observed, the area, perimeter, extent length and branch number of nerve terminals increased with age in both soleus and EDL. The changes were similar between the muscle types, although the changes were more pronounced in the phasic EDL. In 12-month-old animals, 2 months of endurance exercise resulted in significantly larger nerve terminals in both soleus and EDL, suggesting a functional adaptation. Exercised 18- and 24-month-old nerve terminals were smaller than corresponding controls, which indicated that exercise minimized or prevented further age-related nerve terminal elaboration. At all ages the exercised nerve terminals comprised a more homogeneous population than corresponding controls, which indicates that uniform physical activity can modulate NMJ morphometry. The magnitude of the changes suggests that subtle alterations in normal cage activity with advancing age do not have a significant effect on the morphology of nerve terminals. However, the morphology of the NMJ does change significantly in response to physical exercise training. 相似文献
53.
A new human cell line, WSU-BL, was established from a malignant ascitic fluid occurring in a patient with Burkitt's lymphoma. The established line grows in a single-cell suspension with a doubling time of 19 hours and expresses L3 morphologic features by the French-American-British classification. Immunologic study revealed that WSU-BL cells express IgM-lambda both in the cytoplasm and on the surface and react with monoclonal antibodies to B-cell antigens (B1, B4, BL3, BL4, HLA-DR, and common acute lymphoblastic leukemia antigen [CALLA]). These cells are negative for T-cell and myeloid/monocyte antigens as well as Epstein-Barr virus nuclear antigen (EBNA). These results suggest that WSU-BL corresponds to an intermediate stage of B-cell differentiation. Both fresh tumor and WSU-BL cells had a hyperdiploid karyotype carrying the 8;14 chromosome translocation. Molecular studies showed that WSU-BL has a rearrangement of c-myc proto-oncogene and expresses c-myc RNA. Phorbol ester 12-0-tetradecanoylphorbol-13-acetate (TPA) and interferon-gamma (IFN-gamma) were able to induce several phenotypic changes on WSU-BL cells. Two-dimensional gel electrophoresis of total cellular protein showed that either TPA or IFN-gamma induced both the synthesis or loss of several proteins. Analysis of the protein patterns indicated that some proteins were uniquely responsive to either TPA or IFN-gamma and others were common to both. This cell line should be valuable for future studies of cell proliferation, differentiation, and oncogenesis concerning this neoplasm. 相似文献
54.
Steven C. Hayes 《Clinical psychology》2002,9(4):410-415
The combination of a stage model of psychotherapy and treatment manualization has been a major step forward in treatment development and efficacy testing, but not in dissemination. I argue that the technological model of treatment development makes research on the practical application of these technologies difficult. If we continue on our present course, research on dissemination will be uncommon, expensive, and largely irrelevant to the practical issues that need to be faced. It makes more sense to proceed directly to dissemination research. Alternative methods, including manipulated training designs, will permit this, but these fundamentally challenge the implicit assumptions of the stage model. 相似文献
55.
In an independent learning project, 52 third-year medical students carried out a structured self-assessment of two videotaped psycho-social interviews they had conducted with volunteer clients 1 year earlier, as part of a previous course. The interviews had been conducted in small tutorials with feedback from their clients, fellow students and tutors, facilitated by videotape playback. During the sequence of 16 tutorials each student had carried out an early and a late interview and had observed and participated in the discussion of the interviews of 14 peers. Students were asked to tally the frequencies of various interview behaviours, to evaluate the quality of their behaviours, and to establish priorities for future learning. The videotapes were also reliably rated by an independent observer. Students' overall self-assessments correlated 0.46 with those of the independent observer. This correlation was higher than is typically reported in studies of the validity of self-assessment. In absolute terms, the students' mean rating of interviewing performance was 3.2 (adequate plus) which was significantly lower than the observer's mean of 3.6 (adequate to good). Results are discussed in terms of Gordon's (1992) two recommendations for improving the validity of self-assessments and two further suggestions, for paired comparisons and low-threat learning environments, are added. 相似文献
56.
Concomitant administration of cyclosporine and ketoconazole in idiopathic nephrotic syndrome. 总被引:1,自引:1,他引:0
Amr El-Husseini Fathy El-Basuony Ahmed Donia Ihab Mahmoud Nabil Hassan Nagy Sayed-Ahmad Mohamed Sobh 《Nephrology, dialysis, transplantation》2004,19(9):2266-2271
BACKGROUND: The deliberate use of ketoconazole to reduce the need for cyclosporine (CsA) is not new, but it is particularly relevant because of the high cost of CsA. Many studies have documented this benefit in renal and cardiac transplants, but this co-administration has not been reported in patients with nephrotic syndrome. METHODS: This retrospective study included 207 nephrotic patients who were steroid resistant, dependent or frequent relapsers and received CsA therapy. Among these patients 153 received daily ketoconazole therapy in a dose of 50 mg with concomitant decrease of one-third of the CsA dose while 54 patients received CsA alone. The majority of our cases were children (179 were below 18 years) and male to female ratio was 1.7:1. RESULTS: The great majority of the study population received the drugs for 1-2 years. Patients who received CsA and ketoconazole were comparable with those who received CsA alone regarding age, sex, duration of renal disease, renal pathology, severity of nephrotic syndrome, renal function, hepatic function and steroid response. Co-administration of ketoconazole significantly reduced mean doses of CsA by 37% after 1 month and 47% at 1 year with overall net cost savings of 37%. Hepatic functions remained within the normal range in both groups. Additionally, co-administration of ketoconazole significantly improved the response to CsA therapy, successful steroid withdrawal and decreased the frequency of renal impairment. CONCLUSIONS: Co-administration of keto with CsA in idiopathic nephrotic patients significantly reduces CsA costs and may improve its response. 相似文献
57.
L L Keeley S M Sowa T K Hayes J Y Bradfield 《General and comparative endocrinology》1988,72(3):364-373
Ovarian protein content and fat body protein synthesis were measured during the first gonotrophic cycle in virgin female Blaberus discoidalis cockroaches. Protein synthesis was measured for in vitro fat bodies from animals treated with combinations of a juvenile hormone analog (JHA = methoprene) and corpora cardiaca (CC) extracts. Ovarian protein content began to increase on Day 5 of adult life and reached its maximum at Days 20-22. Synthesis of proteins secreted by the in vitro fat body increased by 12-fold between emergence and its maximum on Day 18, then declined to nearly its original level by Day 33. Synthesis of nonsecreted, fat body proteins increased by 4-fold between emergence and a maximum on Day 21, then declined. CC extracts and JHA were administered to decapitated females to determine their regulative effects on fat body protein synthesis. The synthesis by the fat body of nonsecreted proteins was increased by both JHA and CC extracts. In contrast, synthesis of secreted proteins increased only in the presence of JHA. CC extracts, alone, had no effects on the synthesis of secreted proteins, but administration of CC extracts in combination with JHA increased the synthesis of the secreted proteins by 55% above that observed with JHA alone. SDS-PAGE of proteins secreted into the medium by the in vitro fat body demonstrated that JHA stimulated the synthesis of specific polypeptides, whereas CC extracts did not affect the synthesis of specific-secreted polypeptides. These results suggest that JH regulates specific protein synthesis by the fat body of B. discoidalis; neurohormones elevate the general capacity of the fat body for protein synthesis and amplify the specific effects of JH. 相似文献
58.
N Bowling V L Wyss P J Gengo B Utterback R F Kauffman J S Hayes 《European journal of pharmacology》1990,187(2):155-164
Effects of prolonged isoproterenol infusion upon the density of cardiac calcium channels, calcium-mediated contractile responses, and the ability of forskolin to enhance tension development and cyclic AMP accumulation were studied in ventricular muscle preparations from Sprague-Dawley rats. Isoproterenol infusion (400 micrograms/kg per h s.c., 4 days) significantly decreased calcium channel density (Bmax) in cardiac microsomal membranes as quantified by a 32% decrease in specific [3H]nitrendipine binding sites; binding affinity (KD) was unchanged. A 57% decrease of beta-adrenoceptors confirmed homologous down regulation. To examine functional effects of decreased [3H]nitrendipine binding sites, responses to calcium, BAY K8644 and nifedipine were determined in isolated right ventricular strips. Significant decreases in basal developed tension were observed in muscles from isoproterenol-infused rats. However, concentration-dependent increases in contractility in response to CaCl2 or BAY K8644 were comparable, and the negative inotropic effect of nifedipine was unchanged. Whereas isoproterenol infusion was associated with significantly decreased basal cardiac cyclic AMP concentrations, exposure of ventricular strips from either vehicle- or isoproterenol-infused rats to 10 microM forskolin resulted in comparable increases in cyclic AMP and in developed tension. Cumulative, submaximal concentrations of forskolin also produced similar increases in contractility with maximum responses in ventricular strips from vehicle-infused animals attained at 4.4 microM forskolin. Higher concentrations resulted in automaticity. By contrast, ventricle from isoproterenol-infused animals responded to 14.4 microM forskolin with maximal increases in force of contraction. 相似文献
59.
A series of novel, highly potent and selective agonists for the kappa-opioid receptor. 总被引:4,自引:4,他引:0 下载免费PDF全文
A. G. Hayes P. J. Birch N. J. Hayward M. J. Sheehan H. Rogers M. B. Tyers D. B. Judd D. I. Scopes A. Naylor 《British journal of pharmacology》1990,101(4):944-948
1. This paper describes the opioid receptor pharmacology and in vivo activity of several novel benzene-acetamidopiperidine and benzeneacetamidopiperazine analogues. 2. These compounds all showed potent, naloxone-reversible, full agonist activity in the field-stimulated rabbit vas deferens, indicating that they are kappa-opioid agonists; but showed very little activity in the rat or hamster vas deferens, indicating good selectivity with regard to mu- and delta-opioid receptors. 3. They were all potent antinociceptive agents, the most potent compound, GR 103545, having an ED50 value in the mouse abdominal constriction test of 0.25 micrograms kg-1 s.c. The compounds also produced sedation and diuresis, but had little effect on respiration rate or gastrointestinal motility. 4. It is concluded that the seven novel compounds described are all potent and selective agonists for the kappa-opioid receptor. 相似文献
60.
Thomas R Flynn Rabie M Shanti Catherine Hayes 《Journal of oral and maxillofacial surgery》2006,64(7):1104-1113
PURPOSE: The purpose of this study was to identify significant predictors of 4 outcomes in patients with severe odontogenic infections: abscess formation, penicillin therapeutic failure (PTF), length of hospital stay (LOS), and need for reoperation. PATIENTS AND METHODS: We used a prospective case series study design and enrolled 37 consecutive patients admitted for severe odontogenic infection between March 1996 and June 1999. Treatment consisted of intravenous penicillin (PCN) or clindamycin in PCN-allergic patients, surgical incision and drainage, and extraction(s) as soon as possible. Study variables were categorized as demographic, preadmission, time-related, preoperative, anatomic, treatment, microbiologic, and complications. The primary outcome variables were abscess formation, PTF, LOS, and reoperation. Multivariate linear and logistic regression techniques were used to measure associations between study variables and the outcome variables. RESULTS: The sample consisted of 37 subjects (23 male, 14 female) with a mean age of 34.9 +/- 15.8 years. Multivariate analyses, controlling for confounding variables, indicated that culture of Peptostreptococci was a negative predictor of abscess formation. LOS was predicted by the number of infected spaces and duration of operation. There was no significant predictor of PTF or reoperation on multivariate analysis, although PCN-resistant organisms were isolated in all cases of PTF. CONCLUSION: Increased LOS in severe odontogenic infections is predicted by the anatomic extent and severity of the infection and the occurrence of complications such as PTF and the need for reoperation. PTF is significantly associated with later identification of PCN-resistant organisms. The role of Peptostreptococci in abscess formation warrants further investigation. 相似文献