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   16263篇
  免费   1286篇
  国内免费   66篇
耳鼻咽喉   134篇
儿科学   452篇
妇产科学   337篇
基础医学   2239篇
口腔科学   345篇
临床医学   1531篇
内科学   3415篇
皮肤病学   186篇
神经病学   1365篇
特种医学   633篇
外科学   2583篇
综合类   224篇
一般理论   16篇
预防医学   1319篇
眼科学   742篇
药学   1061篇
中国医学   50篇
肿瘤学   983篇
  2022年   107篇
  2021年   228篇
  2020年   129篇
  2019年   231篇
  2018年   237篇
  2017年   171篇
  2016年   197篇
  2015年   253篇
  2014年   382篇
  2013年   654篇
  2012年   879篇
  2011年   969篇
  2010年   519篇
  2009年   516篇
  2008年   818篇
  2007年   922篇
  2006年   891篇
  2005年   931篇
  2004年   837篇
  2003年   863篇
  2002年   835篇
  2001年   228篇
  2000年   233篇
  1999年   211篇
  1998年   214篇
  1997年   177篇
  1996年   167篇
  1995年   150篇
  1994年   145篇
  1993年   125篇
  1992年   179篇
  1991年   159篇
  1990年   163篇
  1989年   155篇
  1988年   135篇
  1987年   157篇
  1986年   115篇
  1985年   171篇
  1984年   160篇
  1983年   153篇
  1982年   166篇
  1981年   162篇
  1980年   121篇
  1979年   114篇
  1978年   128篇
  1977年   134篇
  1975年   106篇
  1974年   98篇
  1973年   104篇
  1972年   88篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
There are inconsistencies in the literature regarding the prevalence of cognitive impairment among individuals with multiple sclerosis (MS). The purpose of this study was to examine perceived cognitive impairment in secondary progressive and relapsing-remitting multiple sclerosis (MS) and to examine the relationship between level of disability, age, and number of years with MS and self-reported cognitive symptoms. The sample consisted of 447 individuals (96 participants with secondary progressive MS and 351 participants with MS) who responded to mailed data collection instruments. The Performance Scales, a self-report measure of disability in eight domains of function, and a sociodemographic data sheet were analyzedfor this study. Of individuals with secondary progressive MS, 83% reported cognitive symptoms, while 82% of individuals with relapsing-remitting MS reported cognitive symptoms. Individuals with secondary progressive MS were reportedly experiencing a significantly greater level of total disability. A statistically significant, strong, positive relationship was found between cognitive symptoms and fatigue for those with secondary progressive MS and those with relapsing-remitting MS. Statistically significant, moderate, positive relationships were also found between cognitive symptoms in those with secondary progressive MS and those with relapsing-remitting MS, and sensory symptoms, vision, hand function, bladder/bowel symptoms, and spasticity. A statistically significant, weak, positive relationship was found between cognitive symptoms and mobility in individuals with relapsing-remitting MS. There was no relationship between cognitive symptoms and mobility in those with secondary progressive MS. Cognitive symptoms were not significantly related to age in those with secondary progressive MS or those with relapsing-remitting MS. In addition, cognitive symptoms were not significantly related to the number of years with MS in individuals with secondary progressive MS or those with relapsing-remitting MS. The perception of cognitive deficits in individuals with MS was found in this study to be even more prevalent than previously reported. Because cognitive deficits occur at all stages of MS, early identification and treatment is essential. Healthcare providers must aggressively screen for cognitive impairment and rehabilitate individuals with MS who exhibit symptoms.  相似文献   
32.
Prostaglandin E 1 has been used for the past 15 years in decreased peripheral arterial perfusion with differing degrees of success. The exact mechanism of action has not been clarified so far. Vasodilatation, increased fibrinolytic activity and an improved cellular metabolism were observed in response to PGE 1 in animal experiments both in vivo and in vitro. In the clinical studies performed so far PGE 1 has been used in cases of decreased peripheral arterial perfusion after functional, inflammatory, degenerative or diabetic arteriopathy (stages IIb-IV). Reduction or alleviation of ischaemic rest pain, as well as a faster healing of tissue necrosis was reported after intaarterial administration, especially in non-controlled, but also in controlled studies. Intravenous administration of PGE 1 had a positive influence on clinical symptoms in non-placebo-randomized patients; in the controlled studies, however, the results were not significant. The greatest therapeutic success can be achieved using intermittent intraarterial administration in decreased peripheral arterial perfusion due to functional or inflammatory arteriopathies.  相似文献   
33.
The objective of this study was to evaluate the effect of implantation of porous-coated anatomic medullary fitting prostheses on stress in the proximal femur. Three-dimensional finite element models of a cadaveric femur before and after implantation were used to evaluate the resulting changes in stress in the bone. Models of the femur were generated automatically from computed tomographic scan data with use of an innovative mesh-generation technique. The models were analyzed for three levels of porous coating (proximal, 5/8, and full), with the assumption of ideal ingrowth (perfect bonding) over porous areas and a frictionless, tension-free surface on smooth areas. All models were loaded and restrained to represent conditions of normal gait. The stresses predicted in the implanted femur are consistent with clinical observations of proximal cortical atrophy (normal stress reduced to 6-9% of normal at the calcar and 50–55% at mid-prosthesis) and of hypertrophy at the porous coating junctions (normal stress at the 5/8-coating junction, 123% of stress proximal to the junction) and hypertrophy near the distal tip of the prosthesis (anterior and posterior normal stresses 200–800% of normal). The fully coated prosthesis induced stresses in the bone near the tip of the prosthesis that were most like stresses in the normal femur (medial and lateral normal stress 105 and 102% of the stress in the normal femur). Below the collar, the normal stress associated with the proximally coated prosthesis was 6% greater than that produced with the other two levels of coating but still was only 2% of normal. The 5/8-coated prosthesis appeared to combine the worst features of the fully coated and proximally coated prostheses–greater stress-shielding at the calcar and higher stress near the tip of the prosthesis.  相似文献   
34.
35.
CASE REPORT: A pregnant woman who was a regular user of anxiolytics was admitted to the maternity ward at 38 weeks and 4 days amenorrhea after a massive overdose of clorazepate dipotassium, a benzodiazepine. The exact quantity ingested was undetermined. The infant, born at 39 weeks, presented no spontaneous breathing and tracheal intubation was necessary in the delivery room. The neonatal blood concentrations of the clorazepate metabolites were very high at delivery (26 mg/l nordiazepam and 3.5 mg/l oxazepam) and showed little change over the next 5 days (16 mg/l nordiazepam and 2.1 mg/l oxazepam, with an apparent half-life of 168 h for nordiazepam and 160 h for oxazepam). By day 6, the infant was still dependent on ventilator support and enterodialysis was begun with repeated doses of activated charcoal (1 g/kg every 6 h by gastric tube). Treatment was continued for 5 days and a spectacular diminution in the serum concentrations of the two metabolites was noted on day 11: 1.5 mg/l nordiazepam and less than 0.1 mg/l oxazepam. The nordiazepam and oxazepam half-lifes were reduced to 42 h and 30 h respectively. The concomitant clinical improvement authorized the weaning from ventilation on day 12. CONCLUSION: This is the first report of the use of enterodialysis to treat severe benzodiazepine poisoning in a neonate. Depuration of the toxin was accelerated and the duration of intensive care was shortened thanks to this technique.  相似文献   
36.
BACKGROUND: Growing evidence indicates that the entorhinal cortex (ECx) might be affected in schizophrenia (SZ) and bipolar disorder (BD). To test whether distinct interneuronal subpopulations might be altered, numbers of parvalbumin-immunoreactive (PVB-IR) neurons were measured in the ECx of BD and SZ subjects. These neurons play a pivotal role within ECx intrinsic circuits. METHODS: Numbers, numerical density, and soma size of PVB-IR neurons were measured in the ECx of normal control (n = 16), BD (n = 10), and SZ (n = 10) subjects. The volume of the ECx was measured in Nissl-stained sections. RESULTS: In BD, decreases of total numbers (p = .02) and numerical densities (p = .01) of PVB-IR neurons were detected in the ECx. Within distinct subregions, reductions were detected in the superficial layers of the lateral (p = .02), intermediate (p = .04), and caudal (p = .01) ECx. In SZ, total numbers and numerical densities were not altered. A reduction of soma size was present in the intermediate ECx (p = .01). Volume was unaffected in either disorder. CONCLUSIONS: In BD, a decrease of PVB-IR neurons may alter intrinsic inhibitory networks within the superficial layers of the ECx. The likely consequence is a disruption of integration and transfer of information from the cerebral cortex to the hippocampus.  相似文献   
37.
BACKGROUND: Many studies have shown differences in cardiac care by racial/ethnic groups without accounting for institutional factors at the location of care. OBJECTIVE: Exploratory analysis of the effect of hospital funding status (public vs private) on emergency department (ED) triage decision making for patients with symptoms suggestive of acute coronary syndromes (ACSs) and on the likelihood of ED discharge for patients with confirmed ACS. STUDY DESIGN AND SETTING: Secondary analysis of data from a randomized controlled trial of 10,659 ED patients with possible ACS in five urban academic public and five private hospitals. The main outcome measures were the sensitivity and specificity of hospital admission for the presence of ACS at public and private hospitals and the adjusted odds of a patient with ACS not being hospitalized at public versus private hospitals. RESULTS: Of 10,659 ED patients, 1,856 had confirmed ACS. For patients with suspected ACS, triage decisions at private hospitals were considerably more sensitive (99 vs 96%; p<.001) but less specific (30 vs 48%; p<.001) than at public hospitals. The difference between hospital types persisted after adjustment for multiple patient-level and hospital-level characteristics. CONCLUSION: Significant differences in triage for patients with suspected ACS exist between public and private hospital EDs, even after adjustment for multiple patient demographic, clinical, and institutional factors. Further studies are needed to clarify the causes of the differences.  相似文献   
38.
Netlines     
  相似文献   
39.
Anesthesia in 'stone man': myositis ossificans progressiva   总被引:1,自引:0,他引:1  
Myositis ossificans progressiva is a rare disease leading to complete ossification of the muscular system. Very little information about this rare disease and its anesthetic implications has appeared in anesthetic literature. This disease is felt to have an autosomal dominant pattern of inheritance and is usually associated with anomalies of the hands and feet. Afflicted patients are frequently misdiagnosed in childhood as having a rheumatologic disorder. Later in life (as true bone is formed in striated muscle, ligaments, and fascia), the correct diagnosis becomes obvious. Although muscles of the heart, diaphragm, larynx, and sphincters are spared, those of the chest wall are not, and pulmonary function progressively deteriorates. Death frequently occurs as a result of a pulmonary infection. Specific anesthetic considerations include positioning to avoid injury, potential need for fiberoptic intubation or tracheostomy, decreased thoracic compliance with the need for increased ventilating pressures, and the ultimate in disuse atrophy contraindicating the use of succinylcholine. Myositis ossificans progressiva can present the anesthesiologist with interesting challenges. Anesthetic management will need to be individualized according to the severity of the disease.  相似文献   
40.
A cohort of 729 chronically mentally ill patients receiving community support services (CSS) were followed over a nine-month period. Receiving needed community support services was shown to predict change in client functioning as measured by the Global Assessment Scale (GAS) even after the initial values on the GAS, as well as demographic, psychiatric, residential and medication maintenance variables were considered. Adequacy of social support from family, friends and others also contributed to predicting change in global functioning of the CSS patients.Johns Hopkins UniversityPresented at the American Psychological Association Annual Meeting, Washington, D.C., August 16, 1992.  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