全文获取类型
收费全文 | 30582篇 |
免费 | 1513篇 |
国内免费 | 406篇 |
专业分类
耳鼻咽喉 | 316篇 |
儿科学 | 1443篇 |
妇产科学 | 1296篇 |
基础医学 | 3665篇 |
口腔科学 | 519篇 |
临床医学 | 1994篇 |
内科学 | 5446篇 |
皮肤病学 | 825篇 |
神经病学 | 1922篇 |
特种医学 | 916篇 |
外国民族医学 | 5篇 |
外科学 | 4989篇 |
综合类 | 899篇 |
一般理论 | 3篇 |
预防医学 | 2044篇 |
眼科学 | 1265篇 |
药学 | 2576篇 |
5篇 | |
中国医学 | 347篇 |
肿瘤学 | 2026篇 |
出版年
2022年 | 278篇 |
2021年 | 454篇 |
2020年 | 307篇 |
2019年 | 344篇 |
2018年 | 458篇 |
2017年 | 382篇 |
2016年 | 496篇 |
2015年 | 550篇 |
2014年 | 729篇 |
2013年 | 1021篇 |
2012年 | 1350篇 |
2011年 | 1394篇 |
2010年 | 888篇 |
2009年 | 712篇 |
2008年 | 1206篇 |
2007年 | 1269篇 |
2006年 | 1282篇 |
2005年 | 1268篇 |
2004年 | 1168篇 |
2003年 | 1165篇 |
2002年 | 1165篇 |
2001年 | 921篇 |
2000年 | 901篇 |
1999年 | 775篇 |
1998年 | 360篇 |
1997年 | 340篇 |
1996年 | 323篇 |
1995年 | 349篇 |
1994年 | 281篇 |
1993年 | 293篇 |
1992年 | 543篇 |
1991年 | 559篇 |
1990年 | 507篇 |
1989年 | 597篇 |
1988年 | 471篇 |
1987年 | 518篇 |
1986年 | 389篇 |
1985年 | 473篇 |
1984年 | 374篇 |
1983年 | 346篇 |
1982年 | 307篇 |
1981年 | 274篇 |
1980年 | 241篇 |
1979年 | 332篇 |
1978年 | 254篇 |
1977年 | 246篇 |
1976年 | 233篇 |
1975年 | 279篇 |
1974年 | 259篇 |
1973年 | 244篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
Melissa Terpstra Ivan Tkác Raghavendra Rao Rolf Gruetter 《Magnetic resonance in medicine》2006,55(5):979-983
Both ultrashort echo-time STEAM and MEGA-PRESS-edited spectroscopy were used to validate noninvasive quantification of vitamin C (ascorbate) in the developing rat brain, where changes in ascorbate concentration have been reported. Despite strong overlap with resonances from glutamine, glutamate, glutathione, and macromolecules, reliable quantification of ascorbate (Cramer-Rao lower bounds<0.2 micromol/g) by LCModel analysis of STEAM (TE=2 ms) spectra was possible at 9.4 T. Ascorbate concentrations quantified from the STEAM spectra were in very good agreement with concentrations calculated from fully resolved ascorbate resonances in MEGA-PRESS-edited spectra measured from identical volumes of interest. Ascorbate concentrations measured using STEAM decreased with increasing postnatal rat age, in agreement with published brain ascorbate concentrations measured in vitro using high-performance liquid chromatography (HPLC). 相似文献
12.
Prevalence of vitamin D depletion among morbidly obese patients seeking gastric bypass surgery 总被引:5,自引:0,他引:5
Arthur M. Carlin M.D. D. Sudhaker Rao MB B.S. F.A.C.P. F.A.C.E. Ali M. Meslemani M.D. Jeffrey A. Genaw M.D. Nayana J. Parikh Shiri Levy M.D. Arti Bhan M.D. Gary B. Talpos M.D. 《Surgery for obesity and related diseases》2006,2(2):696-103
BACKGROUND: Abnormalities in calcium and vitamin D metabolism have been reported after bariatric surgery. The purpose of this study was to evaluate vitamin D nutritional status among morbidly obese patients before gastric bypass surgery. METHODS: We prospectively studied 279 morbidly obese patients seeking gastric bypass surgery for vitamin D nutritional status as assessed by serum 25-hydroxyvitamin D level. In addition, serum samples were analyzed for calcium, alkaline phosphatase (AP), intact parathyroid hormone (PTH), and 1,25-dihydroxyvitamin D. RESULTS: Mean patient age was 43 +/- 9 years; 87% of the study patients were women, and 72% were white. Serum calcium and AP levels were normal in 88% and 89% of the patients, respectively. Vitamin D depletion, defined as serum 25-hydroxyvitamin D level 相似文献
13.
14.
Palat Balachandran M.S. M.Ch. Shaleen Agarwal M.S. M.Ch. Narendra Krishnani M.D. Chandra M. Pandey Ph.D. Ashok Kumar M.S. M.Ch. Sadiq S. Sikora M.S. Rajan Saxena M.S. Vinay K. Kapoor M.S. 《Journal of gastrointestinal surgery》2006,10(6):848-854
The aim of this study was to examine the predictors of long-term survival (>24 months) in patients with gall bladder cancer.
A retrospective review of 117 cases of gall bladder cancer resected between 1989 and 2000. The resections included 80 simple
cholecystectomies and 37 extended procedures. Patients with survival >24 months (n=44) were compared with those having survival
<24 months (n=73) for 17 prognostic factors. Overall median survival was 16 months with a 5-year survival of 27%. T status
(P=.000) and adjuvant chemoradiotherapy (P=.001) were independent predictors of long-term survival. Survival advantage was
seen in T3N+ve disease (P=.007) with extended procedures. Complete (R0) resection was attained in 30 patients with a 5-year
survival advantage of 30% as compared with incomplete (R1) resection (P=.0002). Adjuvant chemoradiotherapy improved survival
in simple cholecystectomy group (P=.0008) but no advantage was seen after extended procedures. Stage III (P=.001) and node-positive
disease (P=.0005) had significant benefit with adjuvant therapy. Poor differentiation and vascular invasion were associated
with poor long-term survival. R0 resection was associated with prolonged survival. Extended procedures improved survival in
patients with T3N+ve disease. Addition of chemoradiotherapy made significant improvement in long-term survival in stage III
and node-positive lesions and in patients undergoing simple cholecystectomy. R0 resection predicted long-term survival in
gall bladder cancer. T3 N+ve disease had better survival after extended procedures. Adjuvant chemoradiotherapy improved survival
in stage III and node-positive disease. Poor differentiation and vascular invasion were adverse predictors of survival. 相似文献
15.
16.
Ashutosh Singh M.Ch. Vidyut Kumar Sinha M.Ch. Jayant Khandekar M.Ch. Nandkishor Agrawal M.Ch. Anil Patwardhan M.Ch. Dr. Jagdish Kharideparkar M.Ch. 《Indian Journal of Thoracic and Cardiovascular Surgery》2006,22(2):121-125
Objective The degree of Left Ventricular Mass Index (LVMI) regression following aortic valve replacement correlates with long-term survival.
This study aims to assess the extent of LVMI regression at 3 months following aortic valve replacement (AVR) with different
types and sizes of mechanical valves in rheumatic aortic valve disease.
Methods The LVMI regression was studied in 34 consecutive patients, undergoing elective AVR for rheumatic aortic stenosis and/or regurgitation.
They were grouped in A and B, matched in age, body surface area and pre-operative LVMI, receiving respectively a tilting disc
and a bileaflet mechanical valve. The LVMI was calculated by M-mode echocardiography using the Devereux' formula pre-operatively
and three months post-operatively. The trend of LVMI reduction was compared between the two groups and amongst the patients
with stenotic, regurgitant and mixed aortic valve, pathologies; and receiving different sizes of valves.
Results The mean preoperative LVMI was 199g±79.5 g/m2. At three months post aortic valve replacement, the mean LVMI was 130g±49.0 g/m2. There was a significant reduction of LVMI post-operatively (p=0.001) at three months follow-up. The extent of LVMI regression
following surgery amongst the groups A and B did not vary significantly (p=0.92). The extent of LVMI regression did not vary
significantly in patients with different aortic valve pathology nor with different sizes of the valves implanted.
Conclusions There is a significant early LVMI regression following aortic valve replacement in rheumatic aortic valve disease. The type
and the size of the mechanical prosthesis or the rheumatic pathology do not appear to influence this regression. 相似文献
17.
Dr. Menon Raj Gopal M.Ch. AlDelamie Taha FRCS Valliathu John FRCS Zacharias Sunny FRCS Lawati Al Adil FRCS Venkatraman M.Ch. 《Indian Journal of Thoracic and Cardiovascular Surgery》2006,22(3):173-177
Background Despite improving surgical techniques, treatment of heart valve disease in children remains controversial. Somatic growth
and adequate anticoagulation are of concern when children undergo valve replacement. We conducted this study to evaluate the
performance of valves in this age group.
Methods 42 children under the age of 13 years who underwent valve replacement were included in this study. Totally, 50 valves were
implanted in 42 patients: 48 were mechanical prostheses, two were bioprosthetic both in pulmonary position. 37 (74%) valves
were implanted in mitral position, 10 (20%) in aortic position, 1 (2%) in tricuspid position and 2 (4%) in pulmonary position.
Preoperatively, 14 (33,3%) patients were in New York Heart Association (NYHA) class IV, while 27 (64.2%) were in NYHA class
III.
Results There were 2 (4.7%) hospital deaths and 2 (4.7%) late deaths while 2 (4.7%) patients were lost to follow up. The mean follow
up period was 9.4 yrs. 35 (83.3%) patients are in NYHA Class I and free of all medications except warfarin. 3 (7.1%) patients
have undergone 5 successful pregnancies. The median INR was 2.23. Major thrombo-embolic episode occurred in 1 (2.3%) patient.
Conclusions In view of the problems of sizing, anticoagulation and need for re-operation at an early age, there is a reluctance to replace
valves in children. This study shows that despite these problems, valve replacement can be undertaken safely and successfully
in children, when repair has failed or not technically feasible. 相似文献
18.
Dr. Arni Raghavendrarao Raghuram M.Ch. Subbiah Kumar MD Kathamuthu Balamurugan DA Arulmurugan DA Ramiah Krishnan M.Ch. Perichiappan Sivakami BS Eluvathingal Varghese John M.Ch. 《Indian Journal of Thoracic and Cardiovascular Surgery》2006,22(3):178-181
Background Beating heart surgery has now become the commonest technique of doing Coronary Artery Bypass Graft Surgery (CABG) in our country.
It is being used even in such high risk situations like diffuse coronary disease and Critical Left Main stem Stenosis (LMCS)
with good results. The aim of this study is to retrospectively review our results in Off-Pump Coronary Artery Bypass Surgery
(OPCAB) in patients with critical left main stem stenosis.
Methods This study is a retrospective analysis of the data of patients who underwent primary coronary artery bypass surgery. During
the period from April 2003 to September 2005 a total of 64 patients underwent OPCAB procedure for critical LMCS. During the
same period 10 patients underwent CABG on Cardio Pulmonary Bypass (CPB). The age range was 36–77yrs. The sex distribution
was M: F 53∶10. Ten patients were done as emergency. 2 of them were on Intra Aortic Balloon Pump (IABP) support preoperatively.
10 patients were high risk with a Euro score of ≥5.
Results Left Internal Mammary Artery (LIMA) was used in 78% of cases. Average grafts per patient was 2.96. The median ventilation
time was 5.91 hrs. New IABP insertion in postoperative period was required in 1 patient. One patient was reexplored for bleeding.
There was one perioperative myocardial infarction. 57% of patients did not need any blood transfusion. There was no conversion
to CPB. There was no operative mortality. Inotropes were used in ten cases.
Conclusions OPCAB is a safe method of revascularization in patients with critical LMCS. Preoperative IABP is useful in patients with cardiogenic
shock. However, there is a place for CPB in patients needing additional procedures like Mitral Valve repair (MV repair) or
Dor's procedure or when the vessels are very diffusely diseased. Those patients who are unstable despite IABP support may
be managed by Beating heart On Pump (BHOP) technique. 相似文献
19.
Carlo Ticconi Emilio Piccione Alessia Belmonte Ch V Rao 《The journal of maternal-fetal & neonatal medicine》2006,19(11):687-692
Human chorionic gonadotropin (HCG) is a molecule with multiple endocrine, paracrine, and immunoregulatory actions. Its importance for the enhancement of fertility, successful implantation, and survival of the conceptus in early gestation is recognized. However, studies conducted worldwide in recent years indicate that HCG may also play a significant role in maintaining pregnancy well after the first trimester. Emerging evidence suggests that different biomolecular and physiologic effects of HCG are concordantly directed toward inhibition of myometrial contractility to maintain pregnancy. These studies have prompted preliminary animal and human testing of HCG for the prevention of preterm birth. This article reviews the current knowledge as well as the future perspectives on HCG as a useful new tool in prematurity prevention. 相似文献
20.
K S Rao N Ananthakrishnan A Banerjee 《The Australian and New Zealand journal of surgery》1988,58(9):723-726
A total of 50 consecutive patients who were treated in JIPMER Hospital between 1970 and 1981 for corrosive injuries of the oesophagus and stomach were analysed. There were 23 males and 27 females. All but seven presented with dysphagia due to an established stricture. In addition seven of them had associated stricture of the stomach. They were treated with either repeated dilatations or, in selected cases, oesophageal replacement. Perforation of the oesophagus is an important complication associated with oesophageal dilatation indicating the need for oesophageal replacement in multiple or long dense strictures. Results are quite satisfactory with both modalities of treatment. However, oesophageal replacement surgery, performed properly in selected cases, offers a permanent solution to these unfortunate victims. 相似文献