全文获取类型
收费全文 | 13199篇 |
免费 | 561篇 |
国内免费 | 456篇 |
专业分类
耳鼻咽喉 | 20篇 |
儿科学 | 418篇 |
妇产科学 | 2043篇 |
基础医学 | 885篇 |
口腔科学 | 373篇 |
临床医学 | 1316篇 |
内科学 | 2223篇 |
皮肤病学 | 144篇 |
神经病学 | 578篇 |
特种医学 | 600篇 |
外科学 | 1162篇 |
综合类 | 1870篇 |
现状与发展 | 1篇 |
一般理论 | 2篇 |
预防医学 | 1128篇 |
眼科学 | 217篇 |
药学 | 446篇 |
中国医学 | 197篇 |
肿瘤学 | 593篇 |
出版年
2023年 | 69篇 |
2022年 | 81篇 |
2021年 | 107篇 |
2020年 | 84篇 |
2018年 | 152篇 |
2017年 | 134篇 |
2016年 | 150篇 |
2015年 | 132篇 |
2014年 | 187篇 |
2013年 | 240篇 |
2012年 | 526篇 |
2011年 | 822篇 |
2010年 | 297篇 |
2009年 | 316篇 |
2008年 | 524篇 |
2007年 | 508篇 |
2006年 | 474篇 |
2005年 | 537篇 |
2004年 | 863篇 |
2003年 | 920篇 |
2002年 | 626篇 |
2001年 | 546篇 |
2000年 | 265篇 |
1999年 | 393篇 |
1998年 | 394篇 |
1997年 | 427篇 |
1996年 | 359篇 |
1995年 | 292篇 |
1994年 | 322篇 |
1993年 | 308篇 |
1992年 | 363篇 |
1991年 | 339篇 |
1990年 | 317篇 |
1989年 | 277篇 |
1988年 | 207篇 |
1987年 | 215篇 |
1986年 | 186篇 |
1985年 | 134篇 |
1984年 | 86篇 |
1983年 | 99篇 |
1982年 | 75篇 |
1981年 | 81篇 |
1980年 | 73篇 |
1979年 | 72篇 |
1978年 | 44篇 |
1977年 | 62篇 |
1976年 | 58篇 |
1975年 | 71篇 |
1974年 | 47篇 |
1973年 | 54篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
F. A. C. JADOUL Research Fellow F. BROUGHTON PIPKIN Lecturer G. D. LAMMING Registrar 《BJOG : an international journal of obstetrics and gynaecology》1982,89(8):633-639
Summary. Plasma renin activity, plasma renin concentration, plasma renin substrate, plasma angiotensin II and plasma aldosterone were measured in 10 true primiparae, normotensive throughout pregnancy, for 4 days after a spontaneous vaginal delivery. The concentration of all the measured variables, except plasma renin substrate, fell steeply over the first 3 days post partum . In four of the 10 patients, all components of the renin-angiotensin system increased in concentration somewhat thereafter, although not to the levels of the first day post partum . There are multiple potential sources of renin in the fetoplacental unit and it is possible that this'pregnancy' renin may be capable of the partial suppression of the maternal renin production during pregnancy. The slight rebound observed in some patients may represent a hunting for re-establishment of non-pregnant values. 相似文献
992.
993.
J. H. KENNEDY Lecturer P. STEWART Senior Registrar D. H. BARLOW Registrar E. HILLAN Research Sister A. A. CALDER Senior Lecturer 《BJOG : an international journal of obstetrics and gynaecology》1982,89(9):704-707
Summary. In a randomized controlled study of 100 women of low parity and favourable induction features, induction of labour by means of a single vaginal tablet containing 3 mg of prostaglandin E2 (PGE2 ) was compared with the conventional method of amniotomy and intravenous oxytocin. Four of the patients (8%) who received the prostaglandin tablet required additional intravenous oxytocin to achieve delivery. The prostaglandin group had a longer mean overall induction-delivery interval but a shorter amniotomy-delivery interval than the oxytocin group. One patient in the PGE2 group and two in the oxytocin group required caesarean section. The PGE2 treated patients expressed a higher level of satisfaction with their method of induction, they required less analgesia, had less blood loss at delivery and their babies had a lower incidence of neonatal jaundice. 相似文献
994.
Cytoplasmic steroid receptors in ovarian tumours 总被引:1,自引:0,他引:1
M. A. QUINN Senior Lecturer P. PEARCE Research Officer R. ROME Consultant Gynaecologist J. W. FUNDER Principal Research Fellow D. FORTUNE Director of Pathology R. J. PEPPERELL Professor of Obstetrics Gynaecology 《BJOG : an international journal of obstetrics and gynaecology》1982,89(9):754-759
Summary. Cytoplasmic oestrogen receptors were measured in 40 primary and four secondary ovarian tumours; of these, 43 tumours were also analysed for cytoplasmic progesterone receptors and 34 tumours for cytoplasmic androgen receptors. Serous tumours were significantly more likely to be oestrogen-receptor positive than mucinous tumours, but the incidence of positive progesterone and androgen receptors was similar in serous, mucinous and endometrioid tumours. The mean oestrogen receptor content of serous tumours was significantly higher than that of endometrioid tumours. Well-differentiated epithelial tumours were significantly more likely to be oestrogen-receptor and progesterone-receptor positive than less differentiated epithelial tumours. Two granulosa cell tumours were oestrogen-receptor positive and one of these was also progesteronereceptor and androgen-receptor positive. Four normal óvaries were also analysed for receptor content and two were found to be androgen-receptor positive. The presence of cytoplasmic receptors in ovarian tumours may explain their reported response to endocrine therapy. 相似文献
995.
Wahr Joyce A.; Parks Reginald; Boisvert Denis; Comunale Mark; Fabian Judith; Ramsay James; Mangano Dennis T.; for the Multicenter Study of Perioperative Ischemia Research Group 《JAMA》1999,281(23):2203-2210
Context Although potassium is critical for normal electrophysiology, the association between abnormal preoperative serum potassium level and perioperative adverse events such as arrhythmias has not been examined rigorously. Objective To determine the prevalence of abnormal preoperative serum potassium levels and whether such abnormal levels are associated with adverse perioperative events. Design and Setting Prospective, observational, case-control study of data collected from 24 diverse US medical centers in a 2-year period from September 1, 1991, to September 1, 1993. Patients A total of 2402 patients (mean [SD] age, 65.1 [10.3] years; 24% female) undergoing elective coronary artery bypass grafting who were not enrolled in another protocol. The study population was identified using systematic sampling of every nth patient, in whichn was based on expected total number of procedures at that center during the study period. Main Outcome Measures Intraoperative and postoperative arrhythmias, the need for cardiopulmonary resuscitation (CPR), cardiac death, and death due to any cause prior to discharge, by preoperative serum potassium level. Results Perioperative arrhythmias occurred in 1290 (53.7%) of 2402 patients, with 238 patients (10.7%) having intraoperative arrhythmias, 329 (13.7%) having postoperative nonatrial arrhythmias, and 865 (36%) having postoperative atrial flutter or fibrillation. The incidence of adverse outcomes was 3.6% for death, 2.0% for cardiac death, and 3.5% for CPR. Serum potassium level less than 3.5 mmol/L was a predictor of serious perioperative arrhythmia (odds ratio [OR], 2.2; 95% confidence interval [CI], 1.2-4.0), intraoperative arrhythmia (OR, 2.0; 95% CI, 1.0-3.6), and postoperative atrial fibrillation/flutter (OR, 1.7; 95% CI, 1.0-2.7), and these relationships were unchanged after adjusting for confounders. The significant univariate association between increased need for CPR and serum potassium level less than 3.3 mmol/L (OR, 3.3; 95% CI, 1.2-9.5) and greater than 5.2 mmol/L (OR, 3.0; 95% CI, 1.1-8.7) became nonsignificant after adjusting for confounders. Conclusions Perioperative arrhythmia and the need for CPR increased as preoperative serum potassium level decreased below 3.5 mmol/L. Although interventional trials are required to determine whether preoperative intervention mitigates these adverse associations, preoperative repletion is low cost and low risk, and our data suggest that screening and repletion be considered in patients scheduled for cardiac surgery. 相似文献
996.
997.
Michael Grinton Jaswant Sandhu Audrey Shwe-Tin David H. W. STEEL Darren Shu Jeng Ting North East Trainee Research in Ophthalmology Network 《Eye (London, England)》2021,35(4):1213
PurposeTo examine the incidence, characteristics and outcomes of posterior capsular rupture (PCR) cases amongst the ophthalmology trainees and to evaluate the trainees’ confidence in managing PCR.MethodsA two-staged cross-sectional study was carried out between September 2017 and April 2018 in the North East of England, UK. All ophthalmology trainees were surveyed on their confidence level in managing PCR and the characteristics and outcomes of their PCR cases.ResultsFifteen (71.4%) out of 21 trainees completed the study. The mean number of phacoemulsification was 268.9 ± 250.9 cases (range, 0–705) per trainee. There were 82 (1.9%) cases of PCR reported among 4303 phacoemulsification. PCR occurred most commonly during quadrant removal (44.0%) and cortex removal (21.3%). The best-corrected visual acuity (in logMAR) improved significantly from 0.47 ± 0.32 preoperatively to 0.20 ± 0.19 postoperatively (p < 0.001). The supervising consultant took over 80.5% of the PCR cases. The PCR rate decreased significantly from 3.1% at 0–100 cases to 0.6% at 301–400 cases (p = 0.004) and to 0.4% at >500 cases (p = 0.005). Confidence in managing PCR (without supervision) improved from 0% (9/9) at junior level to 50% (3/6) at senior level, and the average number of anterior vitrectomies performed was 0.6 ± 0.9 (range: 0.0–2.0).ConclusionsWe observed a low PCR rate among the trainees in our region, with the majority of cases achieving good visual outcome. A significant reduction in PCR rate was observed at the threshold of >500 cases. There is however a lack of confidence among trainees in managing PCR, highlighting the need for devising new training strategies in this area.Subject terms: Lens diseases, Epidemiology, Outcomes research 相似文献
998.
<正>The article by Meves and Zheng(2014)is addressing a continuous shift in the field of spinal cord injury(SCI)research that has occurred over the last century.Before that,the spinal cord was viewed as"hard wired"and treatment considerations were based on observations that axons in the periphery were able to regenerate, 相似文献
999.
谷氨酰胺对猪急性重症胰腺炎后肠源性细菌/内毒素易位的影响 总被引:4,自引:0,他引:4
目的:观察静脉内滴注谷酰胺(Gln)对急性重症胰腺炎(ASP)后肠源性细菌/内毒素易位的保护作用。方法:选健康长白种猪21头,体重16-22kg,雌雄不限,随机分为四组,1组:假手术对照组(n=5);Ⅱ组:ASP对照组n=5);Ⅲ组:ASP+甘氨酸(Gly)组(n=5);Ⅳ组:ASP+Gln组(n=6)。在麻醉状态下,进腹向胰管内注入5%牛磺胆酸钠混合液1ml/kg(内含8000-10000BAE 相似文献
1000.