全文获取类型
收费全文 | 198920篇 |
免费 | 7761篇 |
国内免费 | 401篇 |
专业分类
耳鼻咽喉 | 3406篇 |
儿科学 | 7285篇 |
妇产科学 | 5184篇 |
基础医学 | 27799篇 |
口腔科学 | 5586篇 |
临床医学 | 15356篇 |
内科学 | 36574篇 |
皮肤病学 | 5179篇 |
神经病学 | 18423篇 |
特种医学 | 9746篇 |
外国民族医学 | 24篇 |
外科学 | 32619篇 |
综合类 | 1239篇 |
一般理论 | 50篇 |
预防医学 | 10130篇 |
眼科学 | 5125篇 |
药学 | 13724篇 |
中国医学 | 443篇 |
肿瘤学 | 9190篇 |
出版年
2023年 | 963篇 |
2021年 | 1912篇 |
2020年 | 1513篇 |
2019年 | 1875篇 |
2018年 | 3601篇 |
2017年 | 2965篇 |
2016年 | 3889篇 |
2015年 | 4272篇 |
2014年 | 4741篇 |
2013年 | 6603篇 |
2012年 | 10175篇 |
2011年 | 9737篇 |
2010年 | 5618篇 |
2009年 | 4585篇 |
2008年 | 9251篇 |
2007年 | 10277篇 |
2006年 | 10184篇 |
2005年 | 10685篇 |
2004年 | 10072篇 |
2003年 | 9990篇 |
2002年 | 9837篇 |
2001年 | 6878篇 |
2000年 | 6959篇 |
1999年 | 5956篇 |
1998年 | 1792篇 |
1997年 | 1468篇 |
1996年 | 1140篇 |
1995年 | 939篇 |
1994年 | 876篇 |
1992年 | 2665篇 |
1991年 | 2544篇 |
1990年 | 2467篇 |
1989年 | 2333篇 |
1988年 | 2009篇 |
1987年 | 2027篇 |
1986年 | 1880篇 |
1985年 | 1792篇 |
1984年 | 1371篇 |
1983年 | 1106篇 |
1979年 | 1487篇 |
1978年 | 1085篇 |
1977年 | 931篇 |
1975年 | 1144篇 |
1974年 | 1189篇 |
1973年 | 1075篇 |
1972年 | 1086篇 |
1971年 | 1037篇 |
1970年 | 925篇 |
1969年 | 873篇 |
1968年 | 829篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
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
72.
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
73.
Priv.-Doz. Dr. Rüdiger Dissmann Joachim Schröder MD PhD Prof. Dr. med. Heinz Völler Prof. Dr. med. Steffen Behrens 《Clinical research in cardiology》2006,95(4):241-243
Summary During pacemaker implantation in a patient with permanent atrial fibrillation, it remained impossible to advance a passive
fixation lead with fins through the right atrium. However, a lead with a retractable screw easily passed the right atrium
and was positioned in the right ventricle. Transesophageal echocardiography revealed an extensive net–like perforated Eustachian
valve within the right atrium that had caused entrapment of the anchor fins during lead implantation. Remnants of embryonal
structures within the right atrium should be considered a rare possible barrier during pacemaker implantation. 相似文献
74.
75.
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
76.
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
77.
Catherine Guette Christian Legros Guewen Tournois Max Goyffon Marie-Louise Célérier 《Toxicon》2006,47(6):640-649
In order to establish a venom fingerprint and a peptide profile of the Lasiodora parahybana tarantula venom gland, we used conventional methods such as reversed phase liquid chromatography coupled to an electrospray-ionisation hybrid quadrupole time of flight mass spectrometer (LC/ESI-QqTOFMS), matrix-assisted laser desorption/ionization time-of-flight-MS (MALDI-TOFMS) and direct study of L. parahybana venom by nanospray-ionization QqTOFMS (nanoESI-QqTOFMS) and a new technology for the direct analysis of fresh tissues using MALDI-TOFMS. The analysis of the crude venom allowed the characterization of specific juvenile and adult biomarkers. In situ MALDI analysis of L. parahybana venom gland sections revealed different peptide expression levels all along the gland and non-processed peptide precursors, demonstrating the power of the method for the dynamic investigation of peptide evolution in the venom gland of spiders. 相似文献
78.
Dr. Annette Raabe Cordula Petersen Andreas Krüll 《Strahlentherapie und Onkologie》2007,183(7):360-365
PURPOSE: To study the effect of treatment time prolongation following initial dose acceleration on the response of subcutaneously growing R1H tumor. MATERIAL AND METHODS: Continuous standard fractionation (30 fractions/40 days) was compared to initially accelerated treatment (30 fractions/21 days) followed by five to two fractions per week yielding total treatment times from 40 to 72 days. Local tumor control was assessed as endpoint. RESULTS: Radiation dose to control 50% of the tumors (TCD50%) decreased statistically significant from 83.5 Gy (95% confidence interval [CI]: 78.6 .. 88.4) for standard fractionation to 74.1 Gy (95% CI: 72.7 .. 75.5) determined for all accelerated treatment arms (p = 0.003). Prolongation of treatment time after initial acceleration from 40 to 72 days led to a small but statistically not significant increase in TCD50% from 72.0 Gy (95% CI: 71.0 .. 72.9) to 76.2 Gy (95% CI: 69.9 .. 82.4) corresponding to a repopulated dose of 0.9 Gy per week. This time factor is considerably smaller than for conventional radiation treatment as determined in previous experiments. CONCLUSION: The results indicate that initially accelerated irradiation not only improves local tumor control but also minimizes the negative effect of treatment time prolongation. This might be due to changes in tumor cell repopulation kinetics. 相似文献
79.
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
80.
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