全文获取类型
收费全文 | 170436篇 |
免费 | 6411篇 |
国内免费 | 314篇 |
专业分类
耳鼻咽喉 | 3058篇 |
儿科学 | 6390篇 |
妇产科学 | 4356篇 |
基础医学 | 23940篇 |
口腔科学 | 4789篇 |
临床医学 | 12691篇 |
内科学 | 30942篇 |
皮肤病学 | 4670篇 |
神经病学 | 15686篇 |
特种医学 | 8763篇 |
外国民族医学 | 24篇 |
外科学 | 28302篇 |
综合类 | 1089篇 |
一般理论 | 37篇 |
预防医学 | 7965篇 |
眼科学 | 4582篇 |
药学 | 11771篇 |
中国医学 | 349篇 |
肿瘤学 | 7757篇 |
出版年
2023年 | 772篇 |
2021年 | 1235篇 |
2020年 | 1111篇 |
2019年 | 1288篇 |
2018年 | 2866篇 |
2017年 | 2359篇 |
2016年 | 3296篇 |
2015年 | 3656篇 |
2014年 | 3864篇 |
2013年 | 5428篇 |
2012年 | 8315篇 |
2011年 | 7703篇 |
2010年 | 4602篇 |
2009年 | 3665篇 |
2008年 | 7650篇 |
2007年 | 8478篇 |
2006年 | 8531篇 |
2005年 | 8929篇 |
2004年 | 8495篇 |
2003年 | 8409篇 |
2002年 | 8296篇 |
2001年 | 6180篇 |
2000年 | 6243篇 |
1999年 | 5401篇 |
1998年 | 1582篇 |
1997年 | 1305篇 |
1996年 | 996篇 |
1995年 | 806篇 |
1994年 | 747篇 |
1992年 | 2384篇 |
1991年 | 2313篇 |
1990年 | 2272篇 |
1989年 | 2119篇 |
1988年 | 1851篇 |
1987年 | 1842篇 |
1986年 | 1704篇 |
1985年 | 1639篇 |
1984年 | 1279篇 |
1983年 | 1021篇 |
1979年 | 1375篇 |
1978年 | 1009篇 |
1977年 | 849篇 |
1975年 | 1078篇 |
1974年 | 1112篇 |
1973年 | 1014篇 |
1972年 | 1023篇 |
1971年 | 994篇 |
1970年 | 883篇 |
1969年 | 825篇 |
1968年 | 796篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
In the present paper, the results obtained are shown after a study by means of multivariant statistical analysis, of the quantity of Eimeria spp. oocyst elimination in sheep, bearing in mind the variations observed in the different areas, in the different age-groups, from month to month, and from year to year. Climatic factors, development of immunity, lambing seasons, and poor hygienic conditions seem to be the factors responsible for the statistically significant differences found when analysing the aforementioned main effects. 相似文献
43.
AIMS: In normotensive women with Type 1 diabetes and microalbuminuria we previously found preterm delivery (< 34 weeks) in 23% of the pregnancies. Antihypertensive treatment was initiated in late pregnancy when preeclampsia was diagnosed and diastolic blood pressure > 90 mmHg. From April 2000 our routine was changed and early antihypertensive treatment with methyldopa was initiated if antihypertensive treatment was given prior to pregnancy, if urinary albumin excretion (UAE) was > 2 g/24 h, or blood pressure > 140/90 mmHg. The present study describes the impact of this more aggressive antiypertensive treatment in the prevalence of preterm delivery. METHODS: The old cohort (1995-1999) consisted of 26 and the new cohort (2000-2003) of 20 pregnant women with Type 1 diabetes and microalbuminuria. All were referred before gestational week 17. RESULTS: The cohorts were comparable with regard to age, diabetes duration, prepregnancy body mass index, HbA1c, blood pressure 121 (13)/71 (8) vs. 121 (14)/73 (8) mmHg [mean (sd)] and early UAE 69 (16-278) vs. 74 (30-287) mg/24 h (geometric mean and range). Antihypertensive treatment was initiated in the old cohort at 29 (20-33) weeks, n = 9, and in the new at 13 (0-34) weeks, n = 10. The prevalence of preterm delivery before 34 weeks was reduced from 23% to zero (P = 0.02), preterm delivery before 37 weeks from 62% to 40% (P = 0.15) and preeclampsia from 42% to 20% (P = 0.11). Perinatal mortality occurred in 4% vs. 0%. Birth weight was 3124 (767) g vs. 3279 (663) g. CONCLUSION: Introduction of early antihypertensive treatment with methyldopa in normotensive pregnant women with Type 1 diabetes and microalbuminuria resulted in a significant reduction in preterm delivery before gestational week 34. 相似文献
44.
45.
G Stüttgen 《Zeitschrift für Hautkrankheiten》1989,64(11):971-6, 979
We discuss the senescence of the skin considering both intrinsic aging and photoaging; special regard is paid to the various layers, the microcirculation, and the adnexa of the skin. In particular, the barrier function and microcirculation of the skin has been pointed out. 相似文献
46.
Georges Schüler 《International journal of public health》1986,31(1):39-41
This review on air pollution and lung cancer recapitulates the main issues in this field (urban-rural-gradients; experimental data and occupational epidemiology of exposure to PAH; smoking and occupation as confounders). Definite risk increases have been observed in the vicinity of point emission sources. Within Switzerland lung cancer shows an urban/rural gradient in both sexes. The geographical distribution of the male cases can hardly be explained only by the patterns of smoking alone. 相似文献
47.
N-Hydroxythalidomide (1d), a potential metabolite of thalidomide (1a), was synthesized from N-phthalyglutaminic acid anhydride (1b) and O-tetrahydropyraline hydroxylamine, followed by deprotection. The teratogenicity of 1d was studied using the Hen's-Egg-Test model which had been found applicable for 1a. 1d was more teratogenic to chicken embryos compared to 1a. The percentage of teratogenic malformations in the 1d groups was 28-46%, whereas the percentage in the 1a groups was 20-23%. The oxygen protected precursor N-hydroxythalidomide (1c) was less teratogenic (11-15%). 相似文献
48.
Gastric cancer still represents the second most common cause of gastrointestinal cancers in Germany. A disturbing issue is that at the time of diagnosis there are less than 15% of patients for whom a cure can be achieved. Nowadays, biological, histomorphological, molecular genetic and epidemiological data suggest that Helicobacter pylori eradication may lead to the prevention of gastric pre-neoplastic lesions and even gastric cancer. At present, eradication can be offered to selected patients and populations at increased risk, but more research is required before embarking on general and global H. pylori eradication for gastric cancer prevention. The main challenge is to determine how long mucosal abnormalities remain reversible and gastric cancer development can be halted. 相似文献
49.
M Herbst H Fritz H G Nüsslein B J Manger J R Kalden R Sauer 《Strahlentherapie und Onkologie》1986,162(1):25-30
Eleven patients with refractory rheumatoid arthritis were submitted to a total lymphoid irradiation up to a dose of 20 Gy. A constant improvement of clinical symptoms was observed in four out of the eleven patients already during the treatment and in the other patients not later than two months after. The frequency of attacks decreased and the number of joints involved in the attack was reduced. Morning rigidity and joint swellings decreased. One patient developed joint empyemas 4 and 26 months after the treatment. Four patients died in the meantime. In two patients the cause of death were renal insufficiency and a postoperative cardiogenic shock associated with generalized amyloidosis. The third patient died because of a toxically induced left cardiac decompensation with sepsis that could not be controlled by antibiotic drugs and multiple joint empyemas. The fourth patient developed an abscess after surgical treatment of a Kaposi syndrome. She died three months later from acute left cardiac decompensation. The therapy induced a lymphocytopenia with decrease of T helper lymphocytes and unchanged number of T suppressor lymphocytes. The constant therapy results of total lymphoid irradiation in primary chronic polyarthritis is probably due to this modification in the immune regulation. 相似文献
50.
Esra Baltacio?lu Ferda Alev Akalin Eda Topalo?lu Erkan Süküro?lu Umit Cobano?lu 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2007,104(6):803-808
Ligneous periodontitis (LP) is a rare periodontal disease in which plasminogen deficiency and fibrin deposition both play a part, resulting in characteristic gingival enlargement and periodontal breakdown. Recent data suggest that oxidant/antioxidant changes are significant in the pathology of oral diseases. This study examines the gingival histopathology in 2 cases with LP. To examine the antioxidant (AO) status, the activity of the major AOs glutathione (GSH), catalase (CAT), and glutathione S-transferase (GST) and the malondialdehyde (MDA) levels, a product of lipid peroxidation, were measured and compared with healthy control subjects. The histopathologic examination of the gingiva revealed subepithelial fibrin accumulation and irregular extensive downward proliferation of the epithelium. Biochemical analysis showed that the CAT, GST, and MDA levels were higher in LP patients than in the control subjects, and the GSH level was lower. Our preliminary findings show that in LP, the AO capacity of the gingiva changes or decreases and lipid peroxidation increases, which suggests that oxidative stress is involved in the pathology of the periodontal breakdown observed in this disease. 相似文献