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   40093篇
  免费   2082篇
  国内免费   142篇
耳鼻咽喉   523篇
儿科学   2575篇
妇产科学   717篇
基础医学   4790篇
口腔科学   1133篇
临床医学   2899篇
内科学   7202篇
皮肤病学   1137篇
神经病学   2364篇
特种医学   1183篇
外科学   6010篇
综合类   1287篇
一般理论   17篇
预防医学   2048篇
眼科学   1428篇
药学   3994篇
  1篇
中国医学   350篇
肿瘤学   2659篇
  2023年   332篇
  2022年   960篇
  2021年   1617篇
  2020年   884篇
  2019年   976篇
  2018年   1383篇
  2017年   1007篇
  2016年   1327篇
  2015年   1335篇
  2014年   1967篇
  2013年   2252篇
  2012年   3146篇
  2011年   3065篇
  2010年   1842篇
  2009年   1440篇
  2008年   2060篇
  2007年   2087篇
  2006年   1908篇
  2005年   1679篇
  2004年   1573篇
  2003年   1333篇
  2002年   1151篇
  2001年   777篇
  2000年   707篇
  1999年   589篇
  1998年   266篇
  1997年   214篇
  1996年   221篇
  1995年   186篇
  1994年   157篇
  1993年   134篇
  1992年   351篇
  1991年   339篇
  1990年   359篇
  1989年   329篇
  1988年   285篇
  1987年   241篇
  1986年   235篇
  1985年   228篇
  1984年   175篇
  1983年   122篇
  1982年   68篇
  1981年   75篇
  1980年   69篇
  1979年   109篇
  1978年   71篇
  1977年   89篇
  1976年   66篇
  1973年   62篇
  1971年   61篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Crescent fractures of the pelvis are usually described as posterior sacro iliac fracture dislocations. Rarely anterior displacement of the fractured iliac fragment along with dislocation has been reported in crescent fractures. Four cases of anterior fracture dislocation of the sacro iliac joint managed in the last two years by a single surgeon are presented. The injury mechanism, radiological diagnosis, management protocol along with functional outcomes of all the four patients have been discussed. CT scan is essential in the diagnosis and preoperative planning of this injury pattern. Early fixation along with proper reduction leads to excellent functional outcome in this subset of lateral compression injuries of the pelvis.  相似文献   
992.
Previous research has shown that type 2 diabetes mellitus (T2DM) is associated with white matter microstructural changes, cognitive impairment, and decreased resting-state functional connectivity and spontaneous brain activity. This study used magnetization transfer imaging to examine, for the first time, the integrity of macromolecular protein pools in fronto-striato-thalamic circuits and its clinical and cognitive correlates in patients with T2DM. T2DM patients without mood disorders (n = 20, aged 65.05 ± 11.95 years) and healthy control subjects (HCs; n = 26, aged 62.92 ± 12.71 years) were recruited. Nodes of fronto-striato-thalamic circuits—head of the caudate nucleus (hCaud), putamen, globus pallidus, thalamus—and four cortical regions—rostral and dorsal anterior cingulate cortex, dorsolateral prefrontal cortex, and lateral orbitofrontal cortex—were examined. Compared with HCs, patients with T2DM had significantly lower magnetization transfer ratio (MTR) in bilateral anterior cingulate and hCaud. Reduced MTRs in the above regions showed correlations with T2DM-related clinical measures, including hemoglobin A1c level and vascular risk factors, and neuropsychological task performance in the domains of learning and memory, executive function, and attention and information processing. The impaired biophysical integrity of brain macromolecular protein pools and their local microenvironments in T2DM patients may provide insights into the neurological pathophysiology underlying diabetes-associated clinical and cognitive deficits.  相似文献   
993.
Kumar Sharma 《Diabetes》2015,64(3):663-672
The concept that excess superoxide production from mitochondria is the driving, initial cellular response underlying diabetes complications has been held for the past decade. However, results of antioxidant-based trials have been largely negative. In the present review, the data supporting mitochondrial superoxide as a driving force for diabetic kidney, nerve, heart, and retinal complications are reexamined, and a new concept for diabetes complications—mitochondrial hormesis—is presented. In this view, production of mitochondrial superoxide can be an indicator of healthy mitochondria and physiologic oxidative phosphorylation. Recent data suggest that in response to excess glucose exposure or nutrient stress, there is a reduction of mitochondrial superoxide, oxidative phosphorylation, and mitochondrial ATP generation in several target tissues of diabetes complications. Persistent reduction of mitochondrial oxidative phosphorylation complex activity is associated with the release of oxidants from nonmitochondrial sources and release of proinflammatory and profibrotic cytokines, and a manifestation of organ dysfunction. Restoration of mitochondrial function and superoxide production via activation of AMPK has now been associated with improvement in markers of renal, cardiovascular, and neuronal dysfunction with diabetes. With this Perspective, approaches that stimulate AMPK and PGC1α via exercise, caloric restriction, and medications result in stimulation of mitochondrial oxidative phosphorylation activity, restore physiologic mitochondrial superoxide production, and promote organ healing.  相似文献   
994.
995.
996.
997.
This study investigated the protective effect of melatonin on dexamethasone (Dex), an extensively used anti‐inflammatory and immunosuppressive synthetic glucocorticoid, induced testicular oxidative stress and germ cell apoptosis in golden hamster. Hamsters were randomly divided into four groups (n = 7): group I – control; group II – melatonin treated (10 mg kg?1 day?1); group III – Dex treated (7 mg kg?1 day?1) and group IV – combination of Dex and melatonin. All the injections were administered intraperitoneally for seven consecutive days. The histopathological changes, specific biochemical markers, including antioxidative enzymes, plasma melatonin level and the markers for germ cell apoptosis were evaluated. Dex administration decreased antioxidant enzyme activities (SOD, CAT, GSH‐PX), plasma melatonin level and melatonin receptor (MT1) expression with a concomitant increase in lipid peroxidation (TBARS) and altered testicular histopathology which might culminate into increased germ cell apoptosis as evident from increased Bax/Bcl‐2 ratio and caspase‐3 expression. However, melatonin pre‐treatment enhanced enzyme activities for SOD, CAT, GSH‐PX with a simultaneous decrease in Bax/Bcl‐2 ratio and caspase‐3 expression. Our findings clearly suggest that melatonin improved defence against Dex‐induced testicular oxidative stress and prevented germ cell apoptosis, suggesting a novel combination therapeutic approach for management of male reproductive health.  相似文献   
998.
There are contrary reports of association of lead and cadmium with the decline in semen quality. This study evaluates whether seminal lead (Pb) and cadmium (Cd) at environmental concentration are associated with altered semen quality. We conducted a study of healthy fertile and infertile men 20–43 years of age attending the Andrology Laboratory of Reproductive Biology Department for semen analysis. The semen analysis was carried out according to the WHO 2010 guidelines. Seminal lead and cadmium were estimated by ICP‐AES. The lead and cadmium values were significantly higher in infertile subjects. A negative association between seminal lead or cadmium concentration and sperm concentration, sperm motility and per cent abnormal spermatozoa was found. This study shows that exposure to Pb (5.29–7.25 μg dl?1) and cadmium (4.07–5.92 μg dl?1) might affect semen profile in men. Age, diet, smoking and tobacco chewing habits may have an influence on the increase in exposure to Pb and Cd in the individual subjects.  相似文献   
999.
To identify radiographic and MR features of hip osteoarthritis (OA) related to reduced hip extension during walking. Sixty six subjects, were stratified into those with (n = 36, KL = 2, 3) and without (n = 30, KL = 0, 1) radiographic hip OA. Cartilage and labrum lesions were graded semi‐quantitatively on hip MRI. Alpha angle and lateral center edge (LCE) angle were measured. Sagittal kinematics and kinetics were calculated during walking at speed of 1.35 m/s using 3‐D motion capture. All subjects completed Hip disability and Osteoarthritis Outcome Score (HOOS), timed up and go, and 6 min walk tests. Variables were compared between the two groups using one‐way ANOVA (adjusting for age). Correlations of radiographic and MR parameters with peak hip extension were calculated. The OA group was older, had greater pain, and limitation of function. They also had lower peak hip extension and higher peak hip flexion; and worse acetabular and femoral cartilage lesions. Peak hip extension and flexion correlated with KL grade, cartilage lesions in the inferior and posterior femur. Reduced hip extension and greater hip flexion during walking are present in high functioning (HOOS > 85%) individuals with mild‐moderate hip OA, and are associated with cartilage lesions. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:527–534, 2015.  相似文献   
1000.
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