全文获取类型
收费全文 | 39211篇 |
免费 | 2273篇 |
国内免费 | 107篇 |
专业分类
耳鼻咽喉 | 479篇 |
儿科学 | 1475篇 |
妇产科学 | 692篇 |
基础医学 | 5264篇 |
口腔科学 | 822篇 |
临床医学 | 2822篇 |
内科学 | 9871篇 |
皮肤病学 | 1176篇 |
神经病学 | 3879篇 |
特种医学 | 1027篇 |
外科学 | 5210篇 |
综合类 | 170篇 |
一般理论 | 11篇 |
预防医学 | 3310篇 |
眼科学 | 600篇 |
药学 | 2338篇 |
中国医学 | 140篇 |
肿瘤学 | 2305篇 |
出版年
2023年 | 263篇 |
2022年 | 381篇 |
2021年 | 1159篇 |
2020年 | 559篇 |
2019年 | 1047篇 |
2018年 | 1527篇 |
2017年 | 943篇 |
2016年 | 943篇 |
2015年 | 989篇 |
2014年 | 1149篇 |
2013年 | 1674篇 |
2012年 | 2792篇 |
2011年 | 3018篇 |
2010年 | 1634篇 |
2009年 | 1269篇 |
2008年 | 2404篇 |
2007年 | 2526篇 |
2006年 | 2361篇 |
2005年 | 2337篇 |
2004年 | 2210篇 |
2003年 | 1917篇 |
2002年 | 1885篇 |
2001年 | 1100篇 |
2000年 | 1311篇 |
1999年 | 963篇 |
1998年 | 246篇 |
1997年 | 176篇 |
1996年 | 157篇 |
1995年 | 121篇 |
1994年 | 95篇 |
1993年 | 80篇 |
1992年 | 353篇 |
1991年 | 267篇 |
1990年 | 277篇 |
1989年 | 184篇 |
1988年 | 143篇 |
1987年 | 129篇 |
1986年 | 139篇 |
1985年 | 114篇 |
1984年 | 81篇 |
1983年 | 63篇 |
1982年 | 35篇 |
1979年 | 38篇 |
1975年 | 30篇 |
1974年 | 54篇 |
1973年 | 56篇 |
1972年 | 41篇 |
1971年 | 40篇 |
1970年 | 40篇 |
1969年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
J San Cristóbal I Cearra B Otero T Martínez-Astorquiza H Marín I García-Alonso 《Revista española de enfermedades digestivas》2007,99(1):25-32
OBJECTIVE: An intestinal reperfusion study with two aims: a) to assess the usefulness of intestinal capillary blood flow measurement by laser-Doppler for intestinal reperfusion studies; and b) to compare the effects of racemic and levo forms of folinic acid in treating the syndrome. EXPERIMENTAL DESIGN: A murine model of intestinal ischemia by completely clamping the superior mesenteric artery for 90 minutes. A comparison was made of three treatment groups: saline, folinic acid, and levo-folinic acid. The following factors were analyzed: changes in biochemical parameters (levels of creatine kinase, lactic dehydrogenase, and alkaline phosphatase at 60 minutes, and at two and seven days after restoring blood flow), capillary flow in the jejunum and ileum by laser-Doppler (during ischemia and after the first hour of reperfusion), intestinal mucosa injury, and survival curve. RESULTS: Laser-Doppler provided reliable data on how the different treatments affected capillary flow during intestinal reperfusion. Levo-folinic acid improved capillary flow in the ileum after 25 minutes of reperfusion, and also reduced mucosal injury in the same stretch of intestine by the seventh day post-reperfusion (p<0.05). On the other hand, it produced an initial increase in serum enzymes during reperfusion, and did not modify survival. CONCLUSIONS: The changes observed in intestinal capillary blood flow measurement by laser-Doppler have similarities with the effects of drugs on pathological mucosal changes. We could not prove that the levo form of folinic acid has a stronger protective effect versus racemic folinic acid in intestinal ischemia-reperfusion syndrome. 相似文献
62.
Patients presented at the emergency room with chest pain, non-characteristicECG changes and negative Troponin represent a very frequentclinical dilemma. These patients are often hospitalized unnecessarilyand frequently undergo non-invasive and even invasive investigationswhich turn out to be negative. Occasionally, they may falselybe discharged from the ER and eventually develop a major cardiacevent. The most common and apparently the cheapest test employedin the evaluation of these patients is standard exercise ECG.Jeetley et al.1 prospectively studied a large group ofsuch patients. The patients 相似文献
63.
64.
We investigated the expression of intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen-3 (LFA-3) by thyrocytes and their regulation by cytokines. Immunofluorescence studies on cryostat sections and on freshly dispersed cell preparations showed that ICAM-1 and LFA-3 are barely detectable in non-autoimmune thyrocytes. However, thyrocytes acquired ICAM-1 expression in culture. IFN-gamma, IL-1 beta and TNF-alpha produced a clear enhancement of ICAM-1 expression. When tested in combination, IL-1 beta and TNF-alpha were additive to the IFN-gamma effect. LFA-3 expression was not modulated by these cytokines. In the HT93 thyroid cell line generated by transfection with SV40, ICAM-1 and LFA-3 were both constitutively expressed at high levels. Cytokines modulated ICAM-1 expression similarly, but to a greater extent than in normal thyrocytes. LFA-3 remained unmodified. These results support the notion that normal thyrocytes are immunologically silent cells. The capability of cytokines to induce ICAM-1 together with HLA class I and class II-expression on thyrocytes suggests that under their influence, these cells may express all the surface molecules required for antigen presentation and/or for being recognized as target cells in the context of thyroid autoimmune disease. 相似文献
65.
Effect of olanzapine treatment on platelet glutamine synthetase-like protein and glutamate dehydrogenase immunoreactivity in schizophrenia. 总被引:1,自引:0,他引:1
Gulnur Sh Burbaeva Irina S Boksha Elena B Tereshkina Olga K Savushkina Marina S Turishcheva Lubov I Starodubtseva Oleg S Brusov Margarita A Morozova 《The world journal of biological psychiatry》2006,7(2):75-81
According to contemporary views, the glutamatergic system is implicated in the pathogenesis of schizophrenia, and atypical neuroleptics exert their effects (at least partially) through the glutamatergic system. Immunoreactive glutamate-metabolising enzymes, such as glutamine synthetase-like protein (GSLP) and two glutamate dehydrogenase isoenzymes (GDH), have been discovered in human platelets. The amount of GSLP in the platelets of 40 chronic patients with schizophrenia was found to be significantly higher than in 33 controls (consistent with our previous finding of increased amounts of GSLP in the prefrontal cortex of chronic schizophrenia patients). Moreover, survival analysis of the group of patients treated with olanzapine for 28 weeks showed that the larger amount of GSLP measured in platelets before treatment, the shorter the treatment time needed to achieve a positive clinical response (defined a priori as > or = 20% reduction in PANSS total score from the initial level before the treatment). Hence, GSLP level may serve as a predictor of the treatment duration to achieve a positive outcome with olanzapine. Both GSLP and GDH were found significantly changed in the course of treatment; hence, treatment with olanzapine influences the amounts of glutamate-metabolising enzymes in the platelets of chronic schizophrenia patients. 相似文献
66.
Captopril is a suitable drug to treat high blood pressure in diabetic patients. This Angiotensin-Converting Enzyme Inhibitor (ACEI) is a vasodilator without tachycardia and saline retention. Furthermore, captopril is one of antihypertensive drugs with less adverse effects. It does not induce metabolic changes, improves glucose tolerance and brake the evolution of renal insufficiency. About 50-60% of patients are under control (DBP < 90 mmHg) with captopril monotherapy. In the present paper, were included 64 women and 16 men with diabetes mellitus and mild-moderate hypertension, I-II phase WHO. The average age (mean +/- S.D.) was 66.6 +/- 9.2 years. All patients were treated with 25 mg/12 h of captopril, for one month. If blood pressure was not under control, captopril treatment enhanced to 50 mg/12 h during second month. After this period of two months, patients under control were got out of this study. 37 patients (46.25%) needed a second drug. In randomized form, 20 patients associated 25 mg HCTZ one time a day (CAP + HCTZ); and 17 patients associated 20 mg/12 h of nifedipine retard (CAP + NIF). The study continued for 4 months more. Both treatments reduced blood pressure in significant form without changes statistical significant in the heart rate, weight, glycemia, cholesterol, triglycerides, c-HDL, uric acid, creatinine, Na+ and K+ blood levels. CAP + HCTZ controlled (DBP < 90 mHg) 85% and CAP + NIF 81.25% of patients.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
67.
Margaret J. Tango Evelyn Safaris Margarita Romanella Atousa Aminian Marina Katerelos Christine Somerwille RIek G. Tearle Martin J. Pearse Anthony J.E d'Apice 《Xenotransplantation》1997,4(1):25-33
Abstract: Transgenic expression of the human complement regulatory molecule CD59 in mice and genetic deletion of the major xenoantigen galactose α 1,3 galactose (Gal KO) each resulted in partial protection of spleen cells from lysis by human serum. These protective effects were additive when the two genetic modifications were combined. However, when the effects of these genetic modifications were examined in an ex vivo model in which mouse hearts were perfused with human plasma, it was Gal KO which was the modification which determined protection. CD59 expression alone was not protective and CD59 expression in combination with Gal knockout did not result in a significant additional increase in protection over and above that provided by Gal knockout alone. The likely explanation for this discrepancy between the in vitro and ex vivo data is that the H2-Kb promoter used to drive CD59 expression results I in substantially less expression on endothelium than on spleen cells. 相似文献
68.
Reports of the human teratogenicity of retinoids have raised concern about the potential human teratogenicity of high doses of vitamin A. Nevertheless, there are few human case reports of excess intake of vitamin A during pregnancy and defective outcomes. No epidemiological studies have been carried out on this subject. Here we present the results of an epidemiological study of prenatal exposure to high doses of vitamin A in Spain, using data from the Spanish hospital-based, case-control registry. Although it is difficult to reach conclusions with such a very low exposure level (1.3 per 1,000 livebirths), our results suggest that a teratogenic effect might exist for exposures to high doses of vitamin A (OR = 0.5, p = 0.15 for less than 40,000 FU and OR = 2.7, p = 0.06 for 40,000 1U or more). As we might expect, this effect also seems to be related to the organogenetic status (OR = 5.4, p = 0.1 for 1st –2nd month, OR = 1.8, p = 0.4 for 3rd onwards) at the time of exposure. 相似文献
69.
J I Bilbao J M Longo A Martín-Palanca L Mu?oz-Galindo 《Journal of vascular and interventional radiology : JVIR》1992,3(3):553-555
Two cases are presented in which conventional approaches did not permit dilation of and stent placement in obstructed ureters. In patients with iatrogenic ureteral laceration or rigid ureteral kinking, direct percutaneous translumbar puncture may provide a safe alternative. The authors' technique is described. 相似文献
70.
Following the pioneering work of Ross and Barratt-Boyes, there is currently a strong evidence based on long-term follow-up data that valve homografts are the best valve substitutes in the aortic position. Currently there exists a renewed interest in the use of fresh and cryopreserved homografts as we know that homografts show a prolonged durability together with the lack of thromboembolic complications. Here we present the case histories of 3 patients undergoing aortic valve replacement by fresh homografts sterilized in antibiotic solution. The underlying pathology was infective endocarditis in all 3 patients, a disease that is considered the ideal indication for homograft implantation. Technical details at the time of implantation, their advantages with regard to other replacements devices and the whole process of procurement, manipulation and preservation are commented on. 相似文献