首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   9578篇
  免费   1087篇
  国内免费   13篇
耳鼻咽喉   81篇
儿科学   304篇
妇产科学   215篇
基础医学   1345篇
口腔科学   284篇
临床医学   1106篇
内科学   1809篇
皮肤病学   106篇
神经病学   999篇
特种医学   267篇
外科学   1302篇
综合类   325篇
一般理论   8篇
预防医学   1153篇
眼科学   301篇
药学   600篇
中国医学   11篇
肿瘤学   462篇
  2023年   72篇
  2021年   225篇
  2020年   152篇
  2019年   211篇
  2018年   227篇
  2017年   183篇
  2016年   163篇
  2015年   180篇
  2014年   249篇
  2013年   377篇
  2012年   509篇
  2011年   519篇
  2010年   260篇
  2009年   261篇
  2008年   414篇
  2007年   428篇
  2006年   431篇
  2005年   413篇
  2004年   398篇
  2003年   305篇
  2002年   337篇
  2001年   285篇
  2000年   272篇
  1999年   254篇
  1998年   95篇
  1997年   91篇
  1996年   89篇
  1995年   75篇
  1994年   76篇
  1993年   73篇
  1992年   206篇
  1991年   180篇
  1990年   204篇
  1989年   200篇
  1988年   190篇
  1987年   147篇
  1986年   150篇
  1985年   159篇
  1984年   112篇
  1983年   108篇
  1982年   76篇
  1979年   115篇
  1978年   96篇
  1977年   79篇
  1976年   66篇
  1975年   61篇
  1974年   71篇
  1973年   95篇
  1972年   87篇
  1971年   75篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
The 1985 release of hospital report cards by the Health Care Financing Administration awakened the public's awareness of variations in outcomes following patient treatment. In 1972, the Department of Veterans Affairs initiated an oversight process for all VA-based cardiac surgery programs. In response to Public Law 99-166, the Continuous Improvement in Cardiac Surgery Program (CICSP) national database was developed in 1987. This CICSP effort reported variations in outcomes across VA cardiac programs. In 1997, the CICSP expanded (CICSP-X) to identify the interrelationships of risk factors with processes and structures of care, as well as clinical outcomes. Based on VA findings to date, these quality improvement endeavors appear to have positively affected short-term and longer-term cardiac surgical outcomes. To advance a new patient-focused paradigm for continuous improvement in cardiac surgical care quality for all US citizens, an integrated data-driven reporting approach with broad-based participation should be implemented to optimally improve patient care.  相似文献   
992.
Aim: Kidney transplant outcomes have improved over the past 15 years, partly due to improvements in immunosuppression. We used data from the Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry to examine trends in immunosuppressive use post transplant. Methods: All adult (recipient age 16+ years) kidney‐only transplants performed in Australia from April 1991 to December 2005 were followed to graft loss or December 2005. Immunosuppressive use at induction, 1, 3 and 5 years post transplant were analysed by transplant cohort. Results: Calcineurin‐inhibitors (CNI) were used in most recipients for induction and maintenance immunosuppression, with increasing tacrolimus use. Induction cyclosporin dose increased since 2001 (from 5.8 to 7.9 mg/kg per day), but maintenance cyclosporin and tacrolimus dose decreased (from 3.8 to 3.0 mg/kg per day cyclosporin at 1 year post transplant). CNI‐free induction increased since 2002 (from 1.4% to 8.4%), while CNI‐free maintenance increased throughout the study period. Mycophenolates were the predominant antimetabolite used. Steroid‐free maintenance decreased (from 22.7% to 8.7% at 1 year post transplant), as did median prednisolone doses (from 0.12 to 0.09 mg/kg per day at 1 year post transplant). Sirolimus or everolimus are increasingly used for CNI‐sparing rather than as antimetabolites substitutes. OKT3 or antithymocyte globulin induction decreased, while anti‐CD25 antibody usage increased from 9.5% to 57.1% since 2000. Conclusion: There is a trend to more potent induction immunosuppression with tacrolimus, mycophenolates and anti‐CD‐25 antibodies, but with CNI avoidance or minimization during maintenance phase. While steroid avoidance/cessation decreased, maintenance steroid dose has also decreased. Anti‐CD25 antibodies are now used in >50% of recipients.  相似文献   
993.
Chaze B  McDonald P 《Neurologic Clinics》2008,26(1):325-32; xii-xiii
Winter sports are often associated with high speed, which carries with it the potential for collision. As such, head injuries are among the more commonly encountered injuries in winter-related sporting activities. This article focuses on popular winter sports such as downhill skiing and snowboarding, sledding, snowmobiling, ice skating, and hockey. In virtually all of these activities, the incidence and severity of head injuries can be reduced by the use of appropriate protective headgear.  相似文献   
994.
Neural stem cells reduce brain injury after unilateral carotid ligation   总被引:10,自引:0,他引:10  
Neonatal stroke presents with seizures and results in neurologic morbidity, including epilepsy, hemiparesis, and cognitive deficits. Stem cell-based therapy offers a possible therapeutic strategy for neonatal stroke. We developed an immature mouse model of stroke with acute seizures and ischemic brain injury. Postnatal day 12 CD1 mice received right-sided carotid ligation. Two or 7 days after ligation, mice received an intrastriatal injection of B5 embryonic stem cell-derived neural stem cells. Four weeks after ligation, hemispheric brain atrophy was measured. Pups receiving stem cells 2 days after ligation had less severe hemispheric brain atrophy compared with either noninjected or vehicle-injected ligated controls. Transplanted cells survived, but 3 out of 10 pups injected with stem cells developed local tumors. No difference in hemispheric brain atrophy was seen in mice injected with stem cells 7 days after ligation. Neural stem cells have the potential to ameliorate ischemic injury in the immature brain, although tumor development is a serious concern.  相似文献   
995.
BACKGROUND: Impairment in attention is prominent in schizophrenia and may be a valuable genetic indicator for vulnerability to this disease. AIMS: We set out to characterize the attention deficits that may be associated with genetic liability to schizophrenia. METHODS: We compared attention performance in 55 people with schizophrenia, 95 of their first-degree relatives, and 61 unrelated controls. We also segregated presumed obligate carriers of genetic risk (POCs, N=12) and compared their performance with that of controls. RESULTS: Although the relatives of people with schizophrenia did not significantly differ from the normal controls on the tasks of attention, their scores were significantly ordered such that patients>relatives>normal controls during tasks of sustained and selective attention as measured by the Jonckheere-Terpstra Test (p<.05). Additionally, POCs were significantly worse than normal controls during selective attention tasks such as the Stroop (p=.03) and Letter Cancellation Task (p=.04). CONCLUSIONS: Heterogeneity in the first-degree relatives may have diluted the attention deficits present in those who are at genetic risk for schizophrenia. On the other hand, our findings in the more homogeneous group of POCs suggest that selective attention may be an indicator of genetic liability for schizophrenia.  相似文献   
996.
This study determines in facioscapulohumeral muscular dystrophy (FSHD) and able-bodied controls (1) the regional body composition and (2) the correlation between regional lean tissue mass and the corresponding regional strength. This is a cross-sectional, criterion standard, case-control study at a university based neuromuscular disease clinic. A dual-energy X-ray absorptiometry (DEXA) scanner was used to obtain regional body composition measurements in 14 FSHD and anthropometrically matched control pairs. A dynamometer determined peak isometric strength for the elbow and knee. Compared to controls, FSHD subjects showed increased regional fat tissue mass (p < 0.001-0.017), decreased regional lean tissue mass (p < 0.001-0.010), and decreased strength (p < 0.001-0.020). There was a correlation between quantitative strength and lean tissue mass for both FSHD and controls (r = 0.791-0.906; p < 0.001). FSHD subjects have higher regional fat tissue mass and lower regional lean tissue mass despite similar BMI and anthropometrics. Regional lean tissue mass correlates with strength.  相似文献   
997.
BACKGROUND: Optimal use of disease-modifying antirheumatic drugs (DMARDs) in rheumatoid arthritis is vital if progression of disease is to be reduced. Methotrexate (MTX) and sulfasalazine (SASP) are widely used inexpensive DMARDs, recently often combined despite no firm evidence of benefit from previous studies. Aim: To establish whether a combination of SASP and MTX is superior to either drug alone in patients with rheumatoid arthritis with a suboptimal response to 6 months of SASP. METHODS: A randomised controlled study of step-up DMARD treatment in early rheumatoid arthritis. In phase I, 687 patients received SASP for 6 months. Those with a disease activity score (DAS) > or =2.4 were offered additional treatment in phase II (SASP alone, MTX alone or a combination of the two). The primary outcome measure was change in DAS. RESULTS: At 6 months, 191 (28%) patients had a DAS <2.4, 123 (18%) were eligible but did not wish to enter phase II, 130 (19%) stopped SASP because of reversible adverse events and 165 (24%) entered phase II. DAS at 18 months was significantly lower in those who received combination treatment compared with those who received either SASP or MTX: monotherapy arms did not differ. Improvement in European League Against Rheumatism and American College of Rheumatology 20, 50 and 70 scores favoured combination therapy. CONCLUSIONS: In this "true-to-life" study, an inexpensive combination of DMARDs proved more effective than monotherapy in patients with rheumatoid arthritis with a suboptimal response to SASP. There was no increase in toxicity. These results provide an evidence base for the use of this combination as a component of tight control strategies.  相似文献   
998.
999.
Trends in kidney transplantation in Australia and New Zealand, 1993-2004   总被引:2,自引:0,他引:2  
BACKGROUND: We hypothesize that transplant outcome in Australia and New Zealand has improved despite more unfavorable transplant characteristics. Data from the Australia and New Zealand Dialysis and Transplant registry was used to examine this hypothesis. METHODS: All adult kidney-only transplants from January 1993 to December 2004 in Australia or New Zealand were followed-up until death or December 2005. Outcomes were adjusted for covariates in multivariate models, with transplant year modeled as a continuous variable. RESULTS: Altogether 6764 patients were included. There were proportionately more live donor and primary transplants, older donors and recipients, and higher recipient body mass index, waiting time, and human leukocyte antigen mismatch in recent cohorts. Death-censored graft loss decreased (adjusted hazard ratio: 0.92 [0.90-0.95] per year, P<0.001). This trend was seen at both 0-1 and 1-5 years posttransplant, and was mainly for immune-mediated graft losses. Patient survival improved only in New Zealand, and only for the first posttransplant year (adjusted odds ratio: 0.88 [0.82-0.95] per year, P=0.001). Cardiovascular deaths decreased while infection or cancer deaths were unchanged. Adjusted delayed graft function rates were unchanged. The acute rejection incidence at 6 months decreased (adjusted odds ratio: 0.88 [0.85-0.90] per year, P<0.001). One and 3-year graft function significantly improved, even after adjusting for rejection. All outcomes did not vary by expanded donor criteria status. CONCLUSIONS: Graft survival and function have improved in recent years, but long-term patient survival remains unchanged. With longer follow-up, the improvement in rejection rates and graft function may lead to further improvements in long-term graft survival and potentially better patient survival.  相似文献   
1000.
With the endovascular revolution upon us, the management of aortic aneurysmal disease has changed dramatically. Since 1991, more than 100,000 aneurysms worldwide have been repaired using early-generation and current-generation standardized grafts and this has dramatically reduced the 30-day mortality rates associated with open aortic surgery. A new phenomenon has also arisen from this wonderful technology. The term hybrid means "of different origins" and hybrid approaches to vascular disease involve open and endovascular techniques to achieve a common goal, namely, to prevent death caused by aneurysmal rupture. This article reviews novel approaches to the repair of complex aortic aneurysms and provides several illustrative examples.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号