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   28123篇
  免费   1436篇
  国内免费   156篇
耳鼻咽喉   281篇
儿科学   623篇
妇产科学   656篇
基础医学   3566篇
口腔科学   1066篇
临床医学   2062篇
内科学   7498篇
皮肤病学   721篇
神经病学   2120篇
特种医学   548篇
外科学   4533篇
综合类   185篇
一般理论   3篇
预防医学   2055篇
眼科学   466篇
药学   1556篇
中国医学   125篇
肿瘤学   1651篇
  2023年   214篇
  2022年   456篇
  2021年   974篇
  2020年   457篇
  2019年   924篇
  2018年   1065篇
  2017年   599篇
  2016年   609篇
  2015年   785篇
  2014年   1137篇
  2013年   1440篇
  2012年   2286篇
  2011年   2346篇
  2010年   1370篇
  2009年   1172篇
  2008年   1871篇
  2007年   1952篇
  2006年   1787篇
  2005年   1595篇
  2004年   1478篇
  2003年   1407篇
  2002年   1281篇
  2001年   202篇
  2000年   181篇
  1999年   205篇
  1998年   204篇
  1997年   162篇
  1996年   148篇
  1995年   130篇
  1994年   114篇
  1993年   97篇
  1992年   102篇
  1991年   74篇
  1990年   84篇
  1989年   55篇
  1988年   57篇
  1987年   50篇
  1986年   38篇
  1985年   53篇
  1984年   43篇
  1983年   48篇
  1982年   49篇
  1981年   48篇
  1980年   46篇
  1979年   24篇
  1978年   25篇
  1977年   34篇
  1975年   22篇
  1974年   23篇
  1973年   24篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
The purpose of this study was to evaluate the ability of helical computed tomographic angiography (HCTA) to detect vascular injury in penetrating neck trauma. Thirty-five patients (30 gunshot wounds and 5 stab wounds) were studied prospectively with HCTA. Scans were performed with a 5-mm slice thickness at a 1:1 pitch after injection of 90 ml of nonionic contrast medium (30-second delay) at 3 ml/sec. Results were compared with those for angiography (29), surgery (3), ultrasound (2), and local inspection (1). HCTA correctly revealed 19 normal and 10 abnormal studies. In 8 cases, HCTA revealed irregular vessel margins (3), contrast extravasation (2), lack of vascular enhancement (1), and caliber changes (2). In 2 patients, HCTA revealed indirect signs of injury only. In 6 cases, HCTA findings did not correlate with angiography. HCTA detects both direct and indirect signs of vascular injury. Although indirect findings are more sensitive, the direct evaluation of vessels increases the specificity and has a high negative predictive value.  相似文献   
52.
The role of glutamate in conditioned taste aversion was investigated. Both, in the amygdala (AMYG) and in the lateral hypothalamus (LH) extracellular levels of glutamate were assessed by microdialysis and capillary electrophoresis with laser induced fluorescence detection. Rats were conditioned by pairing a novel flavor (strawberry flavor) with an intraperitoneal injection of lithium chloride. When the conditioned stimulus (strawberry flavored solution) was injected into the mouth of conditioned rats, there was an increase of glutamate release in the AMYG, and a decrease in glutamate release in the LH. These results predicted that glutamate release in the AMYG and the LH was involved in CTA. This possibility was tested by MK-801 (glutamate antagonist) and glutamate microinjections. MK-801 injections in AMYG attenuated the rejection of the novel flavor, and in the LH did not cause any effect on CTA. Glutamate microinjections in the AMYG caused CTA. These results suggest that glutamatergic activity in the AMYG might be a relevant neurochemical correlate and cause of conditioned taste aversion.  相似文献   
53.
54.
We assessed the prevalence of Parkinson's disease in Cantalejo, Spain. In 1994, we screened 1,579 persons (age > or = 40 years) using a high-sensitivity method. Cases fulfilling established clinical criteria were followed for a minimum of 3 years. Prevalences were compared with those from other door-to-door surveys. We detected 27 individuals with parkinsonism, 20 of whom had Parkinson's disease. The prevalence of Parkinson's disease increased with age and, when age-adjusted to European standards, was 9.01 per 1,000 (age 40 years and over; 10.78 in men and 5.23 in women). Of the 11 men, three were in Hoehn & Yahr grades III-IV, but six of the nine women were more severely affected. Overall, we found 18 newly diagnosed cases of parkinsonism, 13 of which were Parkinson's disease, and the majority of which were in men aged 80 years or older with a mean duration of illness of 5 years. Our prevalence figures are the highest reported, apparently because of the inclusion of several very elderly men. Parkinson's disease in Cantalejo is less severe in men than in women, particularly in those newly diagnosed. Despite the low numbers, the high prevalence and sex-related pattern are unexplained but they probably relate to the high sensitivity of the screening method.  相似文献   
55.
56.
57.
OBJECTIVE: To examine glucose tolerance in sputum-positive non-treated pulmonary tuberculosis (TB) patients as part of a general metabolic profile. Subjects. Sixty-three sputum-positive non-treated patients (male and female) attending the pulmonary clinic at Mthatha General Hospital in the Eastern Cape and 89 apparently healthy sex and age-matched volunteers. METHODS: Sixty-three untreated TB patients who came to the Mthatha General Hospital's pulmonary clinic with classic symptoms of TB, confirmed by sputum analysis, were recruited for the study. Eighty-nine apparently healthy sex and age-matched volunteers served as the control group. Anthropometric measurements were taken using an electronic scale. Standard oral glucose tolerance tests (OGTTs) were performed in both groups in the morning after an overnight fast. Anticoagulant-treated blood was analysed for glucose and insulin using Peridochrome Glucose (Boehringer Mannheim, Mannheim, Germany) and radioimmunoassay (RIA) (Diagnostic Products Corporation, Los Angeles, USA) respectively. RESULTS: There was sluggish response to glucose and insulin in the TB patient group compared with the control group. Glucose and insulin levels were significantly higher in patients at 0, 30, 60, 120, and 180 minutes. Analysis of variance gave the following p-values, viz. p = 0.0000, 0.0004, 0.0000, 0.0000 and 0.0000 for glucose, and p = 0.0317, 0.0071, 0.0000, 0.0005 and 0.0000 for insulin respectively. CONCLUSIONS: The results of this study suggest an altered glucose/insulin metabolism in TB patients. This might play an important role in the clinical course of the disease.  相似文献   
58.
OBJECTIVE: Respiratory scleroma (RS) is a progressive, chronic, granulomatous disease caused by Klebsiella rhinoscleromatis. There is only one report of RS association with HLA-DQ3. In this study, molecular association of HLA class II and RS was determined. STUDY DESIGN AND SETTING: Nine RS patients and 163 healthy controls were compared. DQA1, DQB1, and DRB1 loci were typed. RESULTS: Statistical analysis demonstrated association between DQB1*0301 and susceptibility to RS (P(c) = 0.004). Haplotype analysis showed an association of DQA1*03011-DQB1*0301 (P = 1.21E-19) and DRB1*0407-DQA1*03011-DQB1*0301 (P = 0.0002). CONCLUSIONS: Results established that DQA1*03011-DQB1*0301 haplotype is a strong risk factor for development of RS.  相似文献   
59.
Background. A major concern in evaluating dynamic cardiomyoplasty has been whether the synchronous stimulation of latissimus dorsi muscle is essential for benefit or not. We studied 10 patients to determine the efficacy of the systolic augmentation generated by the synchronous electrical stimulation of the latissimus dorsi muscle.

Methods. Left ventricular ejection fraction, end-systolic and end-diastolic volume indexes, and stroke volume index obtained during resting, peak exercise, and recovery periods (“on” values) were compared with those obtained 1 week after cessation of electrical stimulus (“off” values). Double product and estimated total body oxygen consumption at peak exercise were also calculated and compared.

Results. Higher ejection fractions (0.36 ± 0.07 versus 0.33 ± 0.06 at rest, 0.40 ± 0.07 versus 0.33 ± 0.07 peak exercise, and 0.37 ± 0.06 versus 0.31 ± 0.06 at recovery) and lower end-systolic volume indexes with relatively constant end-diastolic volume indexes were observed with the cardiomyostimulator on. Further, exercise response was better with the cardiomyostimulator on. Double product indirectly reflected better myocardial oxygen supply/demand ratio when on at peak exercise (17 ± 2.2 mm Hg × beats/min × 10−3 for on versus 19 ± 2.6 mm Hg × beats/min × 10−3 for off). Estimated total body oxygen consumption was improved at peak exercise when the cardiomyostimulator was functional (12 ± 2.7 mL · kg−1 · min−1 versus 11 ± 2.6 mL · kg−1 · min−1).

Conclusions. Current data suggest a true systolic assist during synchronous contractions of the latissimus dorsi muscle. It is thought, therefore, that synchronous electrical stimulation is essential for maximum benefit and all the beneficial effect of cardiomyoplasty certainly cannot be attributed to simple wrapping itself.  相似文献   

60.
The attainment of adequate renal protection requires strict blood pressure control and a diminution of proteinuria or microalbuminuria to values as near from normalcy as possible. It has been considered that by getting the first, the second could be attained at the same price. Recent data have confirmed that renal protection in hypertensive patients, diabetics or not, requires combination therapy that has to include an angiotensin converting enzyme inhibitor or an angiotensin receptor blocker. A calcium channel blocker can be added to this without renal compromise. A diuretic will also be needed in most cases. Proteinuria will diminish with this combination in particular if up-titration of the drug blocking the effects of angiotensin II is performed. The control of other associated risk factors is also required, in particular smoking and lipids.  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