全文获取类型
收费全文 | 26488篇 |
免费 | 2097篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 221篇 |
儿科学 | 675篇 |
妇产科学 | 636篇 |
基础医学 | 3584篇 |
口腔科学 | 603篇 |
临床医学 | 2839篇 |
内科学 | 5880篇 |
皮肤病学 | 454篇 |
神经病学 | 2419篇 |
特种医学 | 899篇 |
外科学 | 3482篇 |
综合类 | 135篇 |
一般理论 | 22篇 |
预防医学 | 2610篇 |
眼科学 | 337篇 |
药学 | 1922篇 |
中国医学 | 39篇 |
肿瘤学 | 1846篇 |
出版年
2024年 | 41篇 |
2023年 | 356篇 |
2022年 | 111篇 |
2021年 | 378篇 |
2020年 | 476篇 |
2019年 | 504篇 |
2018年 | 969篇 |
2017年 | 942篇 |
2016年 | 885篇 |
2015年 | 699篇 |
2014年 | 744篇 |
2013年 | 1500篇 |
2012年 | 2012篇 |
2011年 | 2168篇 |
2010年 | 936篇 |
2009年 | 528篇 |
2008年 | 1783篇 |
2007年 | 1788篇 |
2006年 | 1671篇 |
2005年 | 1503篇 |
2004年 | 1365篇 |
2003年 | 1299篇 |
2002年 | 1292篇 |
2001年 | 791篇 |
2000年 | 943篇 |
1999年 | 488篇 |
1998年 | 150篇 |
1997年 | 131篇 |
1996年 | 99篇 |
1995年 | 121篇 |
1994年 | 107篇 |
1993年 | 105篇 |
1992年 | 94篇 |
1991年 | 102篇 |
1990年 | 91篇 |
1989年 | 96篇 |
1988年 | 109篇 |
1987年 | 95篇 |
1986年 | 93篇 |
1985年 | 134篇 |
1984年 | 144篇 |
1983年 | 102篇 |
1982年 | 103篇 |
1981年 | 75篇 |
1980年 | 69篇 |
1979年 | 74篇 |
1978年 | 56篇 |
1977年 | 50篇 |
1976年 | 29篇 |
1975年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
21.
S. Lundgren S. Gundersen R. Klepp P. E. Lønning E. Lund S. Kvinnsland 《Breast cancer research and treatment》1989,14(2):201-206
In this prospective, randomized study the clinical response and toxicity of megestrol acetate (MA) and aminoglutethimide (AG) as second-line treatment in patients with metastatic breast cancer was compared. 176 patients were included, and 150 received treatment greater than 8 weeks and are evaluable for treatment response. The two groups did not differ with regard to prognostic factors. Response rate for the AG and MA groups were 34% and 31% respectively, with duration of response of 13.1 and 13.0 months. Stable disease was obtained in 33% and 35% respectively. No difference was observed in survival. Side effects occurred more frequently in the AG group (42%) than in the MA group (18%). 相似文献
22.
A monoclonal antibody to the human platelet glycoprotein IIb/IIIa complex induces platelet activation 总被引:1,自引:0,他引:1
P W Modderman H G Huisman J A van Mourik A E von dem Borne 《Thrombosis and haemostasis》1988,60(1):68-74
The platelet glycoprotein (GP) IIb/IIIa complex functions as the receptor for fibrinogen on activated platelets. The effects of two anti-GPIIb/IIIa monoclonal antibodies on platelet function were studied. These antibodies, 6C9 and C17, recognized different epitopes, which were exclusively present on the undissociated GPIIb/IIIa complex. Whereas C17 inhibited the binding of fibrinogen to platelets and platelet aggregation induced by adenosine diphosphate (ADP) or collagen, 6C9 caused irreversible aggregation of platelets, both in the presence and absence of extracellular fibrinogen. When incubated with unstirred (non-aggregating) platelets, 6C9 induced release of alpha and dense granule-constituents as well as binding of 125I-fibrinogen to platelets. The latter was evidently mediated in part by platelet-derived ADP, since it was inhibited to a large extent by apyrase, the ADP-hydrolyzing enzyme. F(ab')2 fragments of 6C9 did not induce platelet-release reactions but caused (slow) aggregation of platelets in the presence of extracellular fibrinogen. These results indicate that binding of an antibody to a specific site on the platelet GPIIb/IIIa complex may cause fibrinogen-mediated aggregation. The Fc part of the platelet-bound antibody appears to be involved in the induction of platelet release. 相似文献
23.
Lise Pedersen Susanne Holck Torben Schiødt Karin Zedeler Henning T. Mouridsen 《Breast cancer research and treatment》1989,14(1):91-99
Summary One hundred thirty-one breast carcinomas with medullary features, registered in the Danish Breast Cancer Cooperative Group from 1977–1982, have been histopathologically reviewed by two senior pathologists and classified as typical medullary carcinoma (TMC), atypical medullary carcinoma (AMC), and non-medullary carcinoma (NMC). Diagnostic criteria were based on those put forward by Ridolfiet al. and Fisheret al. The procedure was repeated with an interval of about one year by both pathologists. The diagnostic interobserver agreement was 72% with a Kappa of 0.55. The intraobserver agreement was 77% and 63% with Kappa values of 0.64 and 0.44, respectively. To see whether the observed inter- and intraobserver variability had any prognostic implications, diagnostic subgroups for both pathologists were analyzed with Kaplan Meier plots for recurrence-free survival (RFS) and with log rank tests. In the first evaluation pathologist 1 segregated a group of TMC with a significantly better RFS than for the NMC group, and pathologist 2 segregated a group of TMC with a corresponding strong trend. These findings could not, however, be reproduced in the second evaluation. The study indicates that the criteria of TMC and AMC as proposed by Ridolfiet al. need to be sharpened and simplified in order to reduce inter-and intraobserver variability. Larger studies with a control group of infiltrating ductal carcinomas are mandatory to elucidate the clinical importance of the diagnoses of Typical and Atypical Medullary Carcinoma of the breast. 相似文献
24.
B. W. Nielsen T. Bjerke T. M. E. Damsgaard T. Herlin K. Thestrup-Pedersen P. O. Schiøtz 《Inflammation research》1992,35(3-4):170-178
Increased osmotic pressure has been reported to cause non-cytotoxic histamine release (HR) from human basophils, as well as a potentation of HR induced by anti-IgE. In this study, the effects of hyperosmolar Na–K-acetate (300–600 mOsm/kg H2O) on HR was studied in washed human blood cells from newborns, adult volunteers and patients with severe atopic dermatitis. These three patient groups represesented 3 very distinct populations with respect to total plasma IgE content, medians were <0.2 IU/ml, 20.5 IU/ml and 2508 IU/ml, respectively. Increasing osmolarity to 500 mOsm/kg H2O caused little HR in the absence of other stimuli, whereas at 600 mOsm/kg H2O a significant increase in spontaneous HR was seen. The HR induced by anti-IgE and Concanavalin A, acting through the IgE-receptor, was increased approximately twofold at 500 mOsM/kg H2O. Responses were highly correlated to results at 300 mOsm/kg H2O. The use of 600 mOsm/kg H2O buffers caused a further increase in most, but not all blood samples. The potentiation of IgE-receptor-mediated HR when using hyperosmolar media was clearly independent of plasma IgE contents, and did not change the concentration-response to anti-IgE. In contrast, HR induced by the IgE-receptor-independent stimuli, Formyl-met-leu-phe and calcium ionophore A 23187, were not enhanced at all by incrased osmotic pressure. We conclude, that hyperosomolar media selectively enhance IgE-receptor-mediated HR. The use of hyperosmolar media may therefore be beneficial in a diagnostic application of washed blood HR assays use in allergy diagnosis. 相似文献
25.
S. H. Sindrup L. Arendt-Nielsen K. Brøsen P. Bjerring H. R. Angelo B. Eriksen L. F. Gram 《European journal of clinical pharmacology》1992,42(6):587-591
Summary We have studied the hypoalgesic effect of codeine (100 mg) after blocking the hepatic O-demethylation of codeine to morphine via the sparteine oxygenase (CYP2D6) by quinidine (200 mg). The study was performed in 16 extensive metabolizers of sparteine, using a double-blind, randomized, four-way, cross-over design. The treatments given at 3 h intervals during the four sessions were placebo/placebo, quinidine/placebo, placebo/codeine, and quinidine/codeine. We measured pin-prick pain and pain tolerance thresholds to high energy argon laser stimuli before and 1, 2, and 3 h after codeine or placebo.After codeine and placebo, the peak plasma concentration of morphine was 6–62 (median 18) nmol·.l–1. When quinidine pre-treatment was given, no morphine could be detected (<4 nmol·l–1) after codeine. The pin-prick pain thresholds were significantly increased after placebo/codeine, but not after quinidine/codeine compared with placebo/placebo. Both placebo/codeine and quinidine/codeine increased pain tolerance thresholds significantly. Quinidine/codeine and quinidine/placebo did not differ significantly for either pin-prick or tolerance pain thresholds.These results are compatible with local CYP2D6 mediated formation of morphine in the brain, not being blocked by quinidine. Alternatively, a hypoalgesic effect of quinidine might have confounded the results. 相似文献
26.
Background
Despite considerable knowledge about musculoskeletal disorders (MSD) and physical, psychosocial and individual risk factors there is limited knowledge about physical activity as a factor in preventing MSD. In addition, studies of physical activity are often limited to either leisure activity or physical activity at work. Studies among military personnel on the association between physical activity at work and at leisure and MSD are lacking. This study was conducted to find the prevalence of MSD among personnel in the Royal Norwegian Navy and to assess the association between physical activity at work and at leisure and MSD. 相似文献27.
Frequency and causes of shunt revisions in different cerebrospinal fluid shunt types 总被引:3,自引:0,他引:3
B. M. Borgbjerg F. Gjerris M. J. Albeck J. Hauerberg S. E. Børgesen 《Acta neurochirurgica》1995,136(3-4):189-194
Summary Shunt complications and revisions are common in hydrocephalic patients treated with a ventriculo-atrial or a ventriculo-peritoneal shunt. The reported revision rate differs very much but the rate of revision is close to 50% in many papers. Data from 884 hydrocephalic patients treated with various shunt types in the period 1958–1989 were recorded retrospectively in order to evaluate the frequency of revision for various shunt types and secondly to analyse the specific reasons for the shunt revisions.The rate of shunt revision was 45%. The Pudenz shunt was revised more often (62%) than the remaining shunt types. The Hakim and the Orbis-Sigma shunts had fewer revisions (35% and 27%, respectively) than the other observed shunt types. A defect of or an obstruction in the ventricular catheters was a frequent cause of revision followed by a defect or an obstruction of the distal catheter, a displacement of the distal catheter and an acute infection. Because of the higher rate of revision for the Pudenz shunt the rate of the above mentioned specific complications is also higher in most of the subgroups for that specific shunt type. Driven by these experiences it is reasonable to seek to develop and introduce new shunt types in an attempt to reduce the complication rate. 相似文献
28.
A cohort of 38-year-old men and women were studied for leisure time physical exercise in relation to low back pain (LBP), education, work, social class and smoking by a self-administered questionnaire. At the age of 14 years, the subjects had been interviewed by their school doctor regarding history of LBP and radiographs of the thoracic and lumbar spine were taken. The results show no positive correlation between radiographic changes and LBP in the adolescent period and decreased physical activity in adulthood. Physical activity for at least 3 h/week reduces the risk of LBP measured as lifetime, 1-year and point prevalence. Eighty-five percent of the subjects who reported taking physical exercise for at least 3 h/week had participated in sports activity almost constantly since their school days and these reported being in better condition than the rest of the cohort. Otherwise they did not have a healthier mode of life. No physical exercise during leisure time was associated with a short school education, un-skilled work, unemployment and sickness, low social class, divorce, living in an apartment and smoking. Sixty percent had never or not for many years been interested in participating in sports. Badminton and tennis were the most common sports practised (36%), followed by gymnastics (32%), ball games — soccer and team handball - (25%), running (20%) and swimming (18%). Gymnastics and swimming seem to reduce LBP significantly. Our results show a falling interest in participating in sports activities over time, with 68% of the subjects being members of an athletic association previously, but only 29% currently. Women were more physically inactive during leisure time, probably because of their dual role. Logistic regression analysis indicates that physical activity is related to a long school education, high social class and regular sports activity over time. 相似文献
29.
This paper discusses the use of the Milgram obedience experiments and the Tuskegee syphilis study in the bioethical literature. The two studies are presented and a variety of uses of them identified and discussed. It is argued that the use of these studies as paradigms of problematic research relies on a reduction of their complexity. What is discussed is thus often constructions of these studies that are closer to hypothetical examples than to the real studies. 相似文献
30.
The aim of the study was to determine the role of neurogenic damage to pelvic floor muscles on the outcome of Burch colposuspension. Thirty women objectively continent after Burch colposuspension and 18 women with recurrent stress urinary incontinence (RSUI) were investigated with concentric needle electrode electromyography (EMG) in both pubococcygeus muscles and the external anal sphincter muscle. Neurogenic EMG patterns were significantly more often seen in the pubococcygeus muscles in women with RSUI than in women continent after the colposuspension (P<0.05). The distribution of neurogenic EMG patterns in the investigated muscles was significantly more pronounced in women with RSUI than in continent women: at least one pubococcygeus muscle with neurogenic EMG pattern, 72% vs. 34% (P<0.05); both pubococcygeus muscles, 50% vs. 13% (P<0.05); and all three investigated muscles 41% vs. 10% (P<0.05). In conclusion, the results imply an association between the outcome of the Burch colposuspension and the occurrence of neuropathy in the pelvic floor muscles. Occurrence of neurogenic damage in the pubococcygeus muscles seems to impair the outcome of Burch colposuspension. 相似文献