全文获取类型
收费全文 | 6877篇 |
免费 | 335篇 |
国内免费 | 29篇 |
专业分类
耳鼻咽喉 | 137篇 |
儿科学 | 623篇 |
妇产科学 | 99篇 |
基础医学 | 751篇 |
口腔科学 | 170篇 |
临床医学 | 491篇 |
内科学 | 1246篇 |
皮肤病学 | 106篇 |
神经病学 | 354篇 |
特种医学 | 204篇 |
外科学 | 1039篇 |
综合类 | 154篇 |
一般理论 | 2篇 |
预防医学 | 487篇 |
眼科学 | 257篇 |
药学 | 569篇 |
中国医学 | 33篇 |
肿瘤学 | 519篇 |
出版年
2023年 | 37篇 |
2022年 | 101篇 |
2021年 | 229篇 |
2020年 | 146篇 |
2019年 | 179篇 |
2018年 | 176篇 |
2017年 | 138篇 |
2016年 | 191篇 |
2015年 | 171篇 |
2014年 | 287篇 |
2013年 | 326篇 |
2012年 | 465篇 |
2011年 | 440篇 |
2010年 | 306篇 |
2009年 | 212篇 |
2008年 | 339篇 |
2007年 | 347篇 |
2006年 | 357篇 |
2005年 | 330篇 |
2004年 | 252篇 |
2003年 | 247篇 |
2002年 | 186篇 |
2001年 | 93篇 |
2000年 | 68篇 |
1999年 | 77篇 |
1998年 | 51篇 |
1997年 | 33篇 |
1996年 | 39篇 |
1992年 | 61篇 |
1991年 | 63篇 |
1990年 | 43篇 |
1989年 | 70篇 |
1988年 | 46篇 |
1987年 | 56篇 |
1986年 | 62篇 |
1985年 | 49篇 |
1984年 | 40篇 |
1982年 | 36篇 |
1981年 | 39篇 |
1980年 | 40篇 |
1979年 | 55篇 |
1978年 | 37篇 |
1977年 | 36篇 |
1976年 | 41篇 |
1975年 | 51篇 |
1974年 | 61篇 |
1973年 | 42篇 |
1971年 | 46篇 |
1970年 | 47篇 |
1967年 | 35篇 |
排序方式: 共有7241条查询结果,搜索用时 62 毫秒
21.
J Rajeev Shoba Srinath Y C J Reddy M G Shashikiran Satish Chandra Girimaji Shekhar P Seshadri D K Subbakrishna 《Revue canadienne de psychiatrie》2003,48(1):52-55
OBJECTIVE: Recent studies of patients with juvenile bipolar disorder report low rates of recovery and high rates of chronicity. However, we lack data on the short-term outcome. This study examines the pattern of recovery from the index episode in an aggressively treated juvenile sample. METHOD: We assessed 25 subjects (< 16 years) with a diagnosis of mania, using the Diagnostic Interview for Children and Adolescents-Revised) (DICA-R), Young Mania Rating Scale (YMRS), and Children's Global Assessment Scale (CGAS) at intake and at 3 and 6 months. We studied the time taken to recover from the index episode, the level of functioning, and the factors predicting them. RESULTS: After 6 months, 24 (96%) subjects had recovered from the index manic episode. The median time to recovery was 27 days. Total episode length was significantly longer among those with previous affective episodes. CONCLUSIONS: The findings suggest that juvenile-onset mania has high rates of recovery and low rates of chronicity. These differences from the existing literature need further exploration. 相似文献
22.
Madhu Bala Harish Chandra Goel 《Journal of environmental pathology, toxicology and oncology》2004,23(2):139-144
Recent reports showed that whole extract of Podophyllum hexandrum was radioprotective in mice. Podophyllotoxin is one of the major constituents of the whole extract of Podophyllum. In this study we report on the radioprotective action of podophyllotoxin in Saccharomyces cerevisiae yeast. Proliferating yeast cells pretreated with podophyllotoxin (2.5-5.0 microg/mL) for > or =3 hours showed a higher surviving fraction after (60)Co-gamma-irradiation (200-600 Gy) than did the irradiated cells not pretreated with podophyllotoxin. The maximum increase (2.0 times) in surviving fraction was observed in cells treated with 2.5 microg/mL podophyllotoxin, 5 hours before (60)Co-gamma-irradiation (400 Gy). Podophyllotoxin was not mutagenic or recombinogenic at radioprotective doses (2.5 microg/mL). A post-irradiation decrease in revertants and gene convertants was observed in cells treated with podophyllotoxin (2.5 microg/mL podophyllotoxin, -5 hours, 400 Gy). This study indicates that podophyllotoxin is radioprotective in yeast, and its radioprotective effects in higher eukaryotes would be worth investigating. 相似文献
23.
Arthur J. Matas Raja Kandaswamy Kristen J. Gillingham Lois McHugh Hassan Ibrahim Bertram Kasiske Abhinav Humar 《American journal of transplantation》2005,5(10):2473-2478
Concern persists that prednisone-free maintenance immunosuppression in kidney transplant recipients will be associated with an increase in late allograft dysfunction and graft loss. We herein report 5-year follow-up of a trial of prednisone-free maintenance immunosuppression. From October 1, 1999, through January 31, 2005, at our center, 589 kidney transplant recipients were treated with a protocol incorporating discontinuation of their prednisone on postoperative day 6. At 5 years, actuarial patient survival was 91%; graft survival, 84%; death-censored graft survival, 92%; acute rejection-free graft survival, 84% and chronic rejection-free graft survival, 87%. The mean serum creatinine level (+/-SD) at 1 year was 1.6 +/- 0.6; at 5 years, 1.7 +/- 0.8. In all, 86% of kidney recipients with functioning grafts remain prednisone-free as of April 30, 2005. As compared with historical controls, recipients on prednisone-free maintenance immunosuppression had a significantly lower rate of a number of complications, including cataracts (p < 0.001), posttransplant diabetes mellitus (p < 0.001), avascular necrosis (p = 0.001), and fractures (p = 0.004). We conclude that prednisone-related side effects can be minimized in a protocol incorporating prednisone-free maintenance immunosuppression. Five-year graft outcome remains good. 相似文献
24.
Abhinav Kumar Anjana Bagewadi Vaishali Keluskar Mohitpal Singh 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2007,103(2):207-213
OBJECTIVES: To evaluate the efficacy of oral lycopene therapy in patients with oral submucous fibrosis and to compare these effects with a placebo. STUDY DESIGN: Fifty-eight patients with oral submucous fibrosis formed the population for the study and were randomly divided into 3 groups, evaluated weekly over a 2-month period. Patients of group A (n = 21) received 16 mg of lycopene, those of group B (n = 19) received 16 mg of lycopene along with biweekly intralesional steroid injections, and those of group C (n = 18) were given a placebo. Paired and unpaired t tests were used for statistical evaluation. RESULTS: Mouth-opening values for the patients showed an average increase of 3.4 mm, 4.6 mm, and 0.0 mm for patients in groups A, B, and C, respectively. These values were statistically found to be highly significant. CONCLUSIONS: The observed effects suggest that lycopene can and should be used as a first line of therapy in the initial management of oral submucous fibrosis. 相似文献
25.
26.
27.
C. Saravanane S. Robinson Smile S. Sarath Chandra S. Habeebullah 《The Australian & New Zealand journal of obstetrics & gynaecology》1997,37(1):124-125
EDITORIAL COMMENT: We accepted this case report for publication not only because of its rare anecdotal interest, which is considerable, but also since it will warn readers that rectal bleeding in pregnancy may result from an abdominal pregnancy. It is strange that the ultrasonograph seems not to have identified the calcification as a fetus although we are not told that the latter was macerated or misshapen. The editor has never seen or heard of an ectopic pregnancy causing rectal erosion and bleeding although he has reported a primary abdominal pregnancy in which the placenta was implanted on the peritoneum of the pouch of Douglas posteriorly (A); this woman presented at 23 weeks' gestation when retroplacental haemorrhage resulted in a haematoma that bulged into the vagina causing acute urinary retention. One wonders why the placenta did not erode the anterior rectal wall in this more advanced case of primary placental implantment in the pouch of Douglas.
Summary: A rare case of abdominal pregnancy, causing massive rectal bleeding due to invasion of the rectal wall by the placenta, is reported. 相似文献
Summary: A rare case of abdominal pregnancy, causing massive rectal bleeding due to invasion of the rectal wall by the placenta, is reported. 相似文献
28.
29.
Henry R. Halperin Joshua E. Tsitlik Rafael Beyar Nisha Chandra Alan D. Guerci 《Annals of biomedical engineering》1987,15(3-4):385-403
Whether blood flow during cardiopulmonary resuscitation (CPR) results from intrathoracic pressure fluctuations or direct cardiac
compression remains controversial. We developed a mathematical model that predicts that blood flow due to intrathoracic pressure
fluctuations should be insensitive to compression rate over a wide range but dependent on the applied force and compression
duration. If direct compression of the heart plays a major role, however, the model predicts that flow should be dependent
on compression rate and force, but above a threshold, insensitive to compression duration. These differences in hemodynamics
produced by changes in rate and duration form a basis for determining whether blood flow during CPR results from intrathoracic
pressure fluctuations or from direct cardiac compression. The model was validated for direct cardiac compression by studying
the hemodynamics of cyclic cardiac deformation following thoracotomy in four anesthetized, 21–32-kg dogs. As predicted by
the model, there was no change in myocardial or cerebral perfusion pressures when the duration of compression was increased
from 15% to 45% of the cycle at a constant rate of 60/min. There was, however, a significant increase in perfusion pressures
when rate was increased from 60 to 150/min at a constant duration of 45%. The model was validated for intrathoracic pressure
changes by studying the hemodynamics produced by a thoracic vest (vest CPR) in eight dogs. The vest contained a bladder that
was inflated and deflated. Vest CPR changed intrathoracic pressure without direct cardiac compression, since sternal displacement
was <0.8 cm. As predicted by the model and opposite to direct cardiac compression, there was no change in perfusion pressures
when the rate was increased from 60 to 150/min at a constant duration of 45% of the cycle. Manual CPR was then studied in
eight dogs. There was no surgical manipulation of the chest. Myocardial and cerebral blood flows were determined with radioactive
microspheres and behaved as predicted from the model of intrathoracic pressure, not direct cardiac compression. At nearly
constant peak sternal force (378–426 N), flow was significantly increased when the duration of compression was increased from
short (13%–19% of the cycle) to long (40%–47%), at a rate of 60/min. Flow was unchanged, however, for an increase in rate
from 60 to 150/min at constant compression duration. In addition, myocardial and cerebral flow correlated with their respective
perfusion pressures. Thus vital organ perfusion pressures and flow for manual external chest compression are dependent on
the duration of compression, but not on rates of compression of 60 and 150/min. These data are of course similar to those
produced by vest CPR, where intrathoracic pressure is manipulated without sternal displacement, and to those predicted for
movement of blood by intrathoracic pressure changes. These data are, however, opposite to those produced by cardiac deformation
and to those predicted for movement blood by direct cardiac compression. We conclude that intrathoracic pressure fluctuations
generate blood flow during manual CPR. 相似文献
30.
B6.Sle1 mice, congenic for the NZM2410-derived lupus susceptibility locus, Sle1 on chromosome 1 exhibit many of the features seen in human lupus including activated lymphocytes and high titers of antinuclear autoantibodies. Among the different surface molecules that were aberrantly expressed on the B6.Sle1 lymphocytes was Ly-6A/E. Splenic B- and T-lymphocytes but not myeloid cells from B6.Sle1 mice exhibited enhanced levels of Ly-6A/E compared to B6 controls. In particular, MZ B cells, GC B cells and B-cell blasts expressed the highest levels of Ly-6A/E in both strains, with the levels being even higher on B6.Sle1 derived cells. Following stimulation with LPS or anti-IgM, there was a profound up-regulation in Ly-6A/E, particularly on MZ B cells and B-cell blasts. CD4 and CD8 T cells also up-regulated Ly-6A/E after stimulation with anti-CD3 and anti-CD28. These studies were extended to additional autoimmune strains including B6.Sle3, B6.Sle1.lpr and BXSB. Importantly, Ly-6A/E levels on lymphocytes were commensurate with the degree of disease exhibited by these lupus strains. Finally, it appears that increased interferon levels, in addition to antigen receptor stimulation, may also be a factor accounting for elevated Ly-6A/E in lupus. Given these observations it is important to elucidate the functional role of Ly-6A/E in lupus in future studies. 相似文献