全文获取类型
收费全文 | 4207401篇 |
免费 | 340957篇 |
国内免费 | 14987篇 |
专业分类
耳鼻咽喉 | 59046篇 |
儿科学 | 135385篇 |
妇产科学 | 110944篇 |
基础医学 | 645918篇 |
口腔科学 | 116250篇 |
临床医学 | 379095篇 |
内科学 | 759645篇 |
皮肤病学 | 103535篇 |
神经病学 | 352639篇 |
特种医学 | 167767篇 |
外国民族医学 | 643篇 |
外科学 | 646722篇 |
综合类 | 122778篇 |
现状与发展 | 24篇 |
一般理论 | 2456篇 |
预防医学 | 353602篇 |
眼科学 | 97941篇 |
药学 | 295377篇 |
25篇 | |
中国医学 | 11195篇 |
肿瘤学 | 202358篇 |
出版年
2021年 | 56029篇 |
2020年 | 35659篇 |
2019年 | 58841篇 |
2018年 | 73758篇 |
2017年 | 56230篇 |
2016年 | 62200篇 |
2015年 | 75814篇 |
2014年 | 110403篇 |
2013年 | 175925篇 |
2012年 | 112613篇 |
2011年 | 116186篇 |
2010年 | 123170篇 |
2009年 | 125669篇 |
2008年 | 103389篇 |
2007年 | 110099篇 |
2006年 | 119266篇 |
2005年 | 114942篇 |
2004年 | 116359篇 |
2003年 | 106983篇 |
2002年 | 96456篇 |
2001年 | 148758篇 |
2000年 | 143796篇 |
1999年 | 134147篇 |
1998年 | 70689篇 |
1997年 | 66944篇 |
1996年 | 65210篇 |
1995年 | 60813篇 |
1994年 | 54989篇 |
1993年 | 51042篇 |
1992年 | 99616篇 |
1991年 | 96267篇 |
1990年 | 92707篇 |
1989年 | 90114篇 |
1988年 | 84026篇 |
1987年 | 82028篇 |
1986年 | 78127篇 |
1985年 | 76961篇 |
1984年 | 65063篇 |
1983年 | 58169篇 |
1982年 | 47688篇 |
1981年 | 44329篇 |
1980年 | 41727篇 |
1979年 | 56795篇 |
1978年 | 46182篇 |
1977年 | 41083篇 |
1976年 | 38113篇 |
1975年 | 38277篇 |
1974年 | 41863篇 |
1973年 | 40202篇 |
1972年 | 37725篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
A Michel C Vons S Hillaire P Icard G Hazebroucq F Kemeny D Houssin D Franco 《European surgical research. Europ?ische chirurgische Forschung. Recherches chirurgicales européennes》1990,22(5):249-255
The efficiency of Eurocollins or modified University of Wisconsin (UW) solution (MUW) in preserving rat livers was compared. After cold storage with one of the solutions, the livers were transplanted or perfused by collagenase for isolation of hepatocytes. Five of the 6 rats receiving a graft preserved with MUW versus none of the 6 rat receiving a graft preserved with Eurocollins solution survived 24 h or more. A significantly greater number of hepatocytes were isolated from livers preserved with MUW than from livers preserved with Eurocollins solution. This suggests a better reperfusion of MUW-preserved livers by collagenase resulting from less endothelial injury. LDH release by cultured hepatocytes, ketone body production and stimulation by glucagon were not significantly different between the two groups. These results confirm the superiority of MUW solution over Eurocollins in preserving liver grafts. They suggest that the advantage of MUW solution results from better protection of vascular endothelium rather than of hepatocytes. 相似文献
992.
The results of a controlled randomized and prospective clinical study including 113 patients from March 1987 until August 1988 showed that prophylactic drainage in elective resection for cancer of the colon was not necessary. 60 patients received a drain, 53 patients were not drained. The drain turned out to be ineffective even concerning its expected function of draining intraabdominal fluid: its diagnostic and therapeutic value failed in clinical practice. The rate of surgical complications--i.e. anastomotic leakage, impaired wound healing and relaparotomy--was significantly higher in the drained group. In elective colon resection the use of a drain as a routine procedure cannot be recommended. 相似文献
993.
Summary A case of bilateral congenital pseudarthrosis of the clavicle in a baby boy is described. The patient is fully asymptomatic, and no functional impairment is present. This is probably only the seventh case described of this rare congenital anomaly. 相似文献
994.
Serum bone-gla protein after fracture 总被引:2,自引:1,他引:1
K J Obrant B Merle J Bejui P D Delmas 《Clinical orthopaedics and related research》1990,(258):300-303
Serum bone Gamma-carboxyglutamic acid (bone-gla) protein (BGP), a marker of bone formation, was measured in serial blood samples drawn from 14 patients who had fractured at least one of their tibial or femoral diaphyses and from two other patients who had sustained major trauma without fracture but who had been immobilized. A total of 85 samples were taken and analyzed during the first three months after the fractures occurred. Serum BGP significantly increased and positively correlated with the time that had elapsed after the fracture, with an average twofold increase after two months. The fracture site and the duration of immobilization had no influence on the serum BGP levels. Serum BGP levels from the two non-fractured cases increased in the first two weeks with no subsequent consistent trend. These data suggest that serum BGP increases one to two months after a major fracture, possibly as a manifestation of bone repair. Further studies are required to determine the potential clinical value of serum BGP in the management of such patients. 相似文献
995.
Seventy patients, aged 1–20 years, were seen at Jordan University Hospital with high blood pressure (BP) over a 3-year period. BP values ranged from 140 to 230 mmHg for systolic pressure and from 90 to 130 mmHg for diastolic pressure. Essential hypertension was seen in only 6 patients (8.6%); secondary hypertension (n=64 or 91.4%) was due to renal parenchymal diseases (RPD) in 46 patients (65.7%), reno-vascular lesions in 8 (11.4%), renal transplantation in 5 (7.2%), teenage pregnancy in 4 (5.7%), and phaeochromocytoma in 1 patient (1.4%). The aetiologies of RPD were as follows: end-stage renal disease requiring dialysis in 14 patients, acute glomerulonephritis in 14, idiopathic nephrotic syndrome in 10, chronic renal insufficiency in 5, and polycystic kidney in 3 patients. Surgical cure of hypertension was achieved in 5 of the children with reno-vascular lesions and in the patient with phaeochromocytoma. 相似文献
996.
Summary Intracavitary application of ultrasound was first performed for diagnostic purposes in 1967; since that time, it has been
more and more widely used. As far as the gastrointestinal tract is concerned, endoscopically controlled ultrasonic probes
provide visualization of the various layers of the intestinal wall. It is therefore possible to describe lesions of the esophagus,
stomach, and the rectum with regard to their nature and depth of infiltration. Furthermore, periesophageal and perigastric
organs can be visualized. It has become evident that endosonography is particularly important for pretherapeutic staging of
tumors of the esophagus, stomach, and rectum. Here prospective comparative studies confirm the superiority of this new diagnostic
procedure when compared to the methods available to date. 相似文献
997.
It has become common practice to rely on fitted estimates ofapparent in vivo metabolic constants (e.g., Vmax and KM) inparameterization of PBPK models. Yet, quantitative estimatesof precision in these fitted parameters are not routinely reported.Such information is needed to assess the reliability of modelpredictions. The purpose of this study was to assess the precisionin estimates of Vmax and KM for chloroform, accounting for boththe statistical uncertainties in parameter estimates from individualdata sets and any additional uncertainty due to differencesin the parameter estimates derived from various experiments.Joint confidence regions for Vmax and KM from each experiment,generated using maximum likelihood techniques, were used toevaluate these questions. Three previously published data setswere considered. Estimates of Vmax and KM obtained from thesedata sets differed more than could be explained as a consequenceof a limited number of observations, measurement error, or stochasticerror. Issues associated with the use of maximum likelihoodtechniques to estimate joint confidence regions, the estimationof metabolic constants from individual experiments within agas uptake study versus the full data set, the degree of overlapin the joint confidence regions for metabolic constants obtainedfrom separate data sets, and the implications for risk assessmentare discussed. 相似文献
998.
999.
1000.
猕猴桃汁抗环磷酰胺致突变作用的机理 总被引:12,自引:1,他引:11
目的用大鼠外周血双核淋巴细胞微核测试法(CBMNT),在哺乳动物整体水平,研究猕猴桃汁抗环磷酰胺(CP)的致突变作用以及生物转化Ⅱ相酶的作用。方法测定大鼠外周血双核淋巴细胞微核细胞率及肝组织中总谷胱甘肽硫转移酶(GST)、尿苷二磷酸葡萄糖醛酸转移酶(UDPGT)、谷氨酰胺转肽酶(γGT)活性。结果猕猴桃汁对CP诱发的大鼠外周血双核淋巴细胞微核细胞率有显著抑制作用,能明显诱导大鼠肝脏总GST、UDGTP活性,但对γGT活性无显著影响。大鼠外周血双核淋巴细胞微核细胞率与总GST、UDGTP活性呈明显负相关。结论猕猴桃汁抗CP致微核形成作用的机理可能是通过诱导机体外来化合物代谢解毒酶系,加速CP的代谢灭活 相似文献