全文获取类型
收费全文 | 112439篇 |
免费 | 8238篇 |
国内免费 | 411篇 |
专业分类
耳鼻咽喉 | 1204篇 |
儿科学 | 2814篇 |
妇产科学 | 1939篇 |
基础医学 | 15813篇 |
口腔科学 | 2421篇 |
临床医学 | 11712篇 |
内科学 | 23694篇 |
皮肤病学 | 2046篇 |
神经病学 | 11963篇 |
特种医学 | 4374篇 |
外国民族医学 | 6篇 |
外科学 | 15494篇 |
综合类 | 1315篇 |
一般理论 | 89篇 |
预防医学 | 9204篇 |
眼科学 | 1901篇 |
药学 | 7574篇 |
中国医学 | 143篇 |
肿瘤学 | 7382篇 |
出版年
2023年 | 704篇 |
2022年 | 1306篇 |
2021年 | 2596篇 |
2020年 | 1571篇 |
2019年 | 2319篇 |
2018年 | 2790篇 |
2017年 | 2050篇 |
2016年 | 2440篇 |
2015年 | 2783篇 |
2014年 | 3641篇 |
2013年 | 4855篇 |
2012年 | 7452篇 |
2011年 | 7504篇 |
2010年 | 4422篇 |
2009年 | 3972篇 |
2008年 | 6542篇 |
2007年 | 7021篇 |
2006年 | 6512篇 |
2005年 | 6426篇 |
2004年 | 5949篇 |
2003年 | 5341篇 |
2002年 | 5252篇 |
2001年 | 1907篇 |
2000年 | 1813篇 |
1999年 | 1695篇 |
1998年 | 1283篇 |
1997年 | 1060篇 |
1996年 | 867篇 |
1995年 | 865篇 |
1994年 | 735篇 |
1993年 | 679篇 |
1992年 | 1181篇 |
1991年 | 1098篇 |
1990年 | 1036篇 |
1989年 | 994篇 |
1988年 | 889篇 |
1987年 | 837篇 |
1986年 | 855篇 |
1985年 | 852篇 |
1984年 | 699篇 |
1983年 | 617篇 |
1982年 | 587篇 |
1981年 | 488篇 |
1980年 | 434篇 |
1979年 | 526篇 |
1978年 | 422篇 |
1977年 | 384篇 |
1975年 | 340篇 |
1974年 | 366篇 |
1973年 | 358篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
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
103.
We compare the results in recipients of cadaveric renal allografts immunosuppressed with cyclosporine and prednisone to those who received immunosuppression with cyclosporine, azathioprine and prednisone. The 2 groups were compared relative to HLA-ABDR matching, plasma reactive antibodies, cold ischemia time, diabetes as a cause of renal failure and recipient age greater than 50 years. The incidences of clinical allograft rejection and grafts lost to rejection were not significantly different in these 2 groups evaluated at 1 year. In the 2-drug immunosuppressed group the actual 3, 6 and 12-month graft function was 87, 86 and 85%, respectively, compared to 79, 78 and 74%, respectively, in the 3-drug immunosuppressed group. A difference in graft survival was due to graft loss secondary to vascular thrombosis and patient death, and not to immunological events. No advantage was demonstrated for the use of 3-drug immunosuppression for kidney allografts over a 2-drug protocol of cyclosporine and prednisone. 相似文献
104.
Copolymerization of propene with 1-octene (1 mol/1 mol) was performed in toluene at 40°C in the presence of homogeneous methylaluminoxane (MAO)-activated ansa-metallocenes in order to study the role of benzannelation and 2-methyl-substitution of the silylene-bridged bisindenyl ligand on comonomer incoporation, molecular mass, molecular mass distribution, and end groups. While 2-methyl-substitution promoted higher degree of polymerization without affecting copolymerization parameters, benzannelation improved markedly 1-octene incorporation. Only with MAO-activated rac-Me2Si(2-MeBenz[e]Ind)2ZrCl2 catalysts vinylidene end groups were formed exclusively. Molecular weight distribution remains narrow in all experiments. 相似文献
105.
M R?sener J Dichgans R Martin F Harms 《Journal of neurology, neurosurgery, and psychiatry》1995,58(5):637-638
106.
J B Martin J F Annegers J D Curb S Heyden C Howson E S Lee M Lee 《Preventive medicine》1988,17(3):310-320
The effect of caffeine consumption on mortality was evaluated in a historical cohort study of 10,064 diagnosed hypertensive individuals participating in the Hypertension Detection and Follow-up Program from 1973 to 1979. Total caffeine intake level from beverages (coffee and tea) and certain medications, was estimated at the 1-year visit. No evidence was found supporting an association between increased level of caffeine consumption and increased all-cause mortality or cardiovascular disease mortality during the following 4 years. Cigarette smoking was significantly associated with mortality; the association being more pronounced among non- and low-caffeine consumers for all-cause mortality and among non-caffeine consumers for all cardiovascular mortality except cerebrovascular mortality. 相似文献
107.
R Harris B P Marmion G Varkanis T Kok B Lunn J Martin 《Epidemiology and infection》1988,101(3):685-694
The efficiency of the direct detection of Mycoplasma pneumoniae in respiratory exudates by an antigen capture, indirect enzyme immunoassay (Ag-EIA), has been compared with its detection with a cDNA probe ('Gen-Probe assay') directed against the specific ribosomal RNA sequences of the organism ('Mycoplasma pneumoniae Rapid Diagnostic System', Gen-Probe, San Diego, California). Both assays showed excellent specificity against a range of mycoplasma species suspended in negative nasopharyngeal aspirates; only M. pneumoniae and M. genitalium reacted. In experiments with graded doses of viable M. pneumoniae cells suspended in negative nasopharyngeal aspirate, the Gen-Probe assay was more sensitive than Ag-EIA; detection limits were respectively 2 X 10(3) c.f.u./ml (3.2 X 10(5) genomes) and 2.5 X 10(4) c.f.u./ml (4 X 10(6) genomes); detection levels 10-100 times less sensitive than culture. The two assays were also tested on nasopharyngeal aspirates or sputum specimens from 90 patients with respiratory infection; 67 of these were culture- or seronegative for M. pneumoniae and 23 were culture- or seropositive. Ag-EIA detected 21 (91%) of the latter but the Gen-Probe assay detected only 5 (22%). Both assays were negative with the 67 culture-/sero-negatives; there were no Gen-Probe assay positive/Ag-EIA negatives. Overall, it is concluded that although Ag-EIA and the Gen-Probe assay are effective substitutes for culture as a diagnostic procedure, there is a significant problem with samples which are culture-negative and from patients who have good serological evidence of current infection. Possible reasons for the disparity between the two assays are advanced. 相似文献
108.
Martina Ruzickova Claire Slaney Julie Garnham Martin Alda 《Revue canadienne de psychiatrie》2003,48(7):458-461
OBJECTIVE: Several papers have reported higher prevalence of diabetes mellitus (DM) type 2 in patients suffering from bipolar disorder (BD). The possible links between these 2 disorders include treatment, lifestyle, alterations in signal transduction, and possibly, a genetic link. To study this relation more closely, we investigated whether there are any differences in the clinical characteristics of BD patients with and without DM. METHOD: We compared the clinical data of 26 diabetic and 196 nondiabetic subjects from The Maritime Bipolar Registry. Subjects were aged 15 to 82 years, with psychiatric diagnoses of BD I (n = 151), BD II (n = 65), and BD not otherwise specified (n = 6). The registry included basic demographic data and details on the clinical course of bipolar illness, its treatment, and physical comorbidity. In a subsequent analysis using logistic regression, we examined the variables showing differences between groups, with diabetes as an outcome variable. RESULTS: The prevalence of DM in our sample was 11.7% (n = 26). Diabetic patients were significantly older than nondiabetic patients (P < 0.001), had higher rates of rapid cycling (P = 0.02) and chronic course of BD (P = 0.006), scored lower on the Global Assessment of Functioning Scale (P = 0.01), were more often on disability for BD (P < 0.001), and had higher body mass index (P < 0.001) and increased frequency of hypertension (P = 0.003). Lifetime history of treatment with antipsychotics was not significantly associated with an elevated risk of diabetes (P = 0.16); however, the data showed a trend toward more frequent use of antipsychotic medication among diabetic subjects. CONCLUSIONS: Our findings suggest that the diagnosis of DM in BD patients is relevant for their prognosis and outcome. 相似文献
109.
Christopher Martin Stephen McKenzie David Ames 《International journal of geriatric psychiatry》1994,9(5):393-398
In order to determine whether a specialist psychogeriatric nursing home was fulfilling its intended role of caring for the most behaviourally disturbed dementia sufferers, 24 of its demented residents were compared with 28 demented individuals discharged from a psychiatric unit to ordinary nursing homes and 30 mobile dementia sufferers in nursing home wards of a geriatric centre. Those in the psychogeriatric nursing home showed more disturbed behaviours than those in the other two settings. Scores on the Rating Scale for Aggressive Behaviour in the Elderly were compared with degree of cognitive impairment for the first time in the literature and showed no correlation with degree of cognitive impairment for the first time in the literature and showed no correlation with congnitive performance. 相似文献
110.
Martin Haupt Alexander Kurz Stefan Pollmann Barbara Romero 《Journal of neurology》1992,239(5):248-250
Summary Ninety outpatients with Alzheimer's disease according to ICD-10 diagnostic draft criteria were studied to test the hypothesis that cases with a familial aggregation are different from cases without such an aggregation with respect to cognitive impairment. In all cases the diagnosis of Alzheimer's disease was confirmed by prospective observation within 12 months of initial evaluation. Patients were divided into two groups: one consisting of 23 patients with a familial aggregation, the other consisting of 67 patients without secondary cases among first-degree relatives. By means oft-tests differences in impairment of cognitive functions between the groups were calculated. The results did not yield statistically significant differences between the groups for any of the neuropsychologically investigated cognitive deficits. Thus the hypothesis that the presence of a familial aggregation may lead to a distinct phenotype in Alzheimer's disease was not confirmed. 相似文献