全文获取类型
收费全文 | 234083篇 |
免费 | 11553篇 |
国内免费 | 388篇 |
专业分类
耳鼻咽喉 | 3058篇 |
儿科学 | 7327篇 |
妇产科学 | 4763篇 |
基础医学 | 33753篇 |
口腔科学 | 5327篇 |
临床医学 | 18482篇 |
内科学 | 51646篇 |
皮肤病学 | 6216篇 |
神经病学 | 20861篇 |
特种医学 | 7044篇 |
外国民族医学 | 101篇 |
外科学 | 29042篇 |
综合类 | 977篇 |
一般理论 | 62篇 |
预防医学 | 21596篇 |
眼科学 | 4561篇 |
药学 | 16494篇 |
中国医学 | 699篇 |
肿瘤学 | 14015篇 |
出版年
2023年 | 1240篇 |
2022年 | 848篇 |
2021年 | 3437篇 |
2020年 | 2040篇 |
2019年 | 3872篇 |
2018年 | 7422篇 |
2017年 | 4872篇 |
2016年 | 4856篇 |
2015年 | 5436篇 |
2014年 | 5666篇 |
2013年 | 9158篇 |
2012年 | 15973篇 |
2011年 | 15918篇 |
2010年 | 7922篇 |
2009年 | 5891篇 |
2008年 | 13704篇 |
2007年 | 14678篇 |
2006年 | 13514篇 |
2005年 | 13379篇 |
2004年 | 12540篇 |
2003年 | 11445篇 |
2002年 | 10851篇 |
2001年 | 6163篇 |
2000年 | 6247篇 |
1999年 | 5542篇 |
1998年 | 897篇 |
1997年 | 744篇 |
1996年 | 717篇 |
1992年 | 3230篇 |
1991年 | 2900篇 |
1990年 | 2777篇 |
1989年 | 2535篇 |
1988年 | 2401篇 |
1987年 | 2223篇 |
1986年 | 2125篇 |
1985年 | 1923篇 |
1984年 | 1422篇 |
1983年 | 1210篇 |
1982年 | 691篇 |
1979年 | 1240篇 |
1978年 | 866篇 |
1977年 | 823篇 |
1975年 | 828篇 |
1974年 | 1022篇 |
1973年 | 1049篇 |
1972年 | 983篇 |
1971年 | 965篇 |
1970年 | 903篇 |
1969年 | 935篇 |
1968年 | 817篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
993.
M Tod F Mentré Y Merlé A Mallet 《Journal of pharmacokinetics and biopharmaceutics》1998,26(6):689-716
The expectation of the determinant of the inverse of the population Fisher information matrix is proposed as a criterion to evaluate and optimize designs for the estimation of population pharmacokinetic (PK) parameters. Given a PK model, a measurement error model, a parametric distribution of the parameters and a prior distribution representing the belief about the hyperparameters to be estimated, the EID criterion is minimized in order to find the optimal population design. In this approach, a group is defined as a number of subjects to whom the same sampling schedule (i.e., the number of samples and their timing) is applied. The constraints, which are defined a priori, are the number of groups, the size of each group and the number of samples per subject in each group. The goal of the optimization is to determine the optimal sampling times in each group. This criterion is applied to a one-compartment open model with first-order absorption. The error model is either homoscedastic or heteroscedastic with constant coefficient of variation. Individual parameters are assumed to arise from a lognormal distribution with mean vector M and covariance matrix C. Uncertainties about the M and C are accounted for by a prior distribution which is normal for M and Wishart for C. Sampling times are optimized by using a stochastic gradient algorithm. Influence of the number of different sampling schemes, the number of subjects per sampling schedule, the number of samples per subject in each sampling scheme, the uncertainties on M and C and the assumption about the error model and the dose have been investigated. 相似文献
994.
995.
996.
Magí Farré María-Teresa Terán Pere N. Roset Marta Mas Marta Torrens J. Camí 《Psychopharmacology》1998,140(4):486-495
Abuse liability and acute subjective and psychomotor effects of flunitrazepam were assessed in ten methadone-maintained males
with history of benzodiazepine and alcohol use, who voluntarily participated in a double-blind, controlled, cross-over, randomized
clinical trial. There were six experimental sessions in which a single oral dose of flunitrazepam 1, 2, and 4 mg; triazolam
0.5 and 0.75 mg; and placebo was given. Evaluations included physiological measures; psychomotor performance tasks (simple
reaction time, Digit Symbol Substitution Test, balance task, Maddox-wing device); and self-administered subjective effects
questionnaires [Addiction Research Center Inventory (ARCI), Profile of Mood States (POMS), a series of visual analog scales
(VAS)]. All drugs but flunitrazepam 1 mg caused an impairment of psychomotor tasks. Effects were more evident with the highest
doses of both drugs. Only flunitrazepam 4 mg produced a significant decrease in balance time. Triazolam 0.75 mg induced increases
in sedation measured by ARCI-PCAG, depression in POMS, and VAS-drowsiness scores. Flunitrazepam 4 mg caused euphoria-related
effects as measured by increases in ARCI-MBG and “high” scores in the VAS. Our findings of flunitrazepam-induced euphoria
in methadone-maintained subjects together with epidemiological evidence of flunitrazepam abuse by opioid dependents, suggest
that it may be included in the group of benzodiazepines with a relatively high abuse potential.
Received: 13 February 1998/Final version: 1 May 1998 相似文献
997.
A. Kiss Á. Csontai M. Merksz P. Szónyi Gy. Gorácz 《International urology and nephrology》1996,28(6):787-792
A retrospective study was performed between 1985 and 1994 on paediatric patients operated for asymptomatic intrascrotal or
testicular palpable masses. Tumour was suspected in each case and it was surgically explored. Twenty-six children were affected,
their age ranging between 9 days and 14 years. In 11 cases testicular torsion, in 4 epididymitis and in another 2 dystrophic
calcification were found. Tumours, including rather rare alterations, were observed in only 9 children. The present results
draw attention to the tumour-like occurrence of testicular torsions and other benign alterations of the scrotum. 相似文献
998.
Short-term outcome analysis of a randomized study comparing laparoscopic vs open colectomy for colon cancer 总被引:19,自引:6,他引:13
A. M. Lacy J. C. García-Valdecasas J. M. Piqué S. Delgado E. Campo J. M. Bordas P. Taurá L. Grande J. Fuster J. L. Pacheco J. Visa 《Surgical endoscopy》1995,9(10):1101-1105
The authors examined the impact of the laparoscopic approach on the early outcome of resected colon carcinomas. The role of laparoscopic techniques in the treatment of colon carcinomas is questionable. Previous studies have suggested technical feasibility of surgical resections of these cancers by laparoscopic means and have implied a benefit to laparoscopic technique for patients undergoing colorectal resections. A prospective, randomized study was conducted comparing laparoscopic assisted colectomy (LAC) open colectomy (OC) for colon cancer. We present the preliminary results in relation to the short-term outcome and judge the feasibility of the laparoscopic procedure to as a way of performing accurate oncologic resection and staging. Benefit has been demonstrated with LAC in this setting. Passing flatus, oral intake, and discharge from hospital occurred earlier in LAC- than OC-treated patients The mean operative time was significantly longer in the LAC group than in the OC group. The overall morbidity was significantly lower in the LAC group. No significant differences were observed between both groups in the number of lymph nodes removed or the pathological stage following the Astler-Coller modification of the Dukes classification. The laparoscopic approach improves the short-term outcome of segmental colectomies for colon cancer. However, the further follow-up of these patients will allow us to answer in the near future whether or not the LAC may influence the long-term outcome.Presented at the annual meeting of the Society of American Gastrointestinal Surgeons (SAGES), Orlando, FL, USA, 11–14 March 1995 相似文献
999.
The mode of action and the structure of a herbicide in complex with its target: binding of activated hydantocidin to the feedback regulation site of adenylosuccinate synthetase. 总被引:4,自引:0,他引:4
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
R Fonné-Pfister P Chemla E Ward M Girardet K E Kreuz R B Honzatko H J Fromm H P Sch?r M G Grütter S W Cowan-Jacob 《Proceedings of the National Academy of Sciences of the United States of America》1996,93(18):9431-9436
(+)-Hydantocidin, a recently discovered natural spironucleoside with potent herbicidal activity, is shown to be a proherbicide that, after phosphorylation at the 5' position, inhibits adenylosuccinate synthetase, an enzyme involved in de novo purine synthesis. The mode of binding of hydantocidin 5'-monophosphate to the target enzyme was analyzed by determining the crystal structure of the enzyme-inhibitor complex at 2.6-A resolution. It was found that adenylosuccinate synthetase binds the phosphorylated compound in the same fashion as it does adenosine 5'-monophosphate, the natural feedback regulator of this enzyme. This work provides the first crystal structure of a herbicide-target complex reported to date. 相似文献
1000.
P Nyirády L Pirót A Altorjay A Pelényi M Merksz A Kiss A Csontai 《Acta chirurgica Hungarica》1998,37(3-4):201-204
There are recurrences and postoperative hydrocele of varicocele after any kind of surgical treatment. Laparoscopic clipping and dissection of internal spermatic vessels was performed without any complication in 73 children to treat varicocele in our department between 1995 and 1998. We have used a new method to detect etiological factors at laparoscopic surgery. The well-known Linton and Trendelenburg test was adapted to detect incidental collateral veins in 73 patients. Using these test, collateral veins were detected in 16 boys. The testicular artery identified in most of the cases as a pulsatile vessel. The operating time was 10-25 minutes. Laparoscopic varicocelectomy is a safe, effective treatment causing minimal discomfort and allowing patients an early to return to activity. These results suggest this technique a viable alternative to open ligation in paediatric urological practice. 相似文献