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   69834篇
  免费   4870篇
  国内免费   221篇
耳鼻咽喉   901篇
儿科学   1660篇
妇产科学   960篇
基础医学   8926篇
口腔科学   1102篇
临床医学   7259篇
内科学   14981篇
皮肤病学   898篇
神经病学   7014篇
特种医学   2683篇
外国民族医学   5篇
外科学   12187篇
综合类   705篇
一般理论   53篇
预防医学   4750篇
眼科学   1300篇
药学   4761篇
中国医学   72篇
肿瘤学   4708篇
  2023年   520篇
  2022年   898篇
  2021年   2074篇
  2020年   1247篇
  2019年   1854篇
  2018年   2273篇
  2017年   1597篇
  2016年   1693篇
  2015年   1954篇
  2014年   2801篇
  2013年   3529篇
  2012年   5471篇
  2011年   5680篇
  2010年   3036篇
  2009年   2788篇
  2008年   4590篇
  2007年   4674篇
  2006年   4448篇
  2005年   4248篇
  2004年   3814篇
  2003年   3656篇
  2002年   3253篇
  2001年   631篇
  2000年   505篇
  1999年   551篇
  1998年   668篇
  1997年   541篇
  1996年   430篇
  1995年   365篇
  1994年   346篇
  1993年   314篇
  1992年   353篇
  1991年   341篇
  1990年   298篇
  1989年   264篇
  1988年   260篇
  1987年   233篇
  1986年   225篇
  1985年   215篇
  1984年   235篇
  1983年   181篇
  1982年   173篇
  1981年   164篇
  1980年   163篇
  1979年   161篇
  1978年   130篇
  1977年   103篇
  1976年   84篇
  1975年   90篇
  1974年   92篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Dactylolysis spontanea is an idiopathic condition affecting the fifth toe, and sometimes other toes, that is frequently bilateral, with lesions in different stages. Between 1977 and 1999, a total 6000 radiographic studies of the feet were reviewed in a mainly African American population in Chicago, Illinois. After an initial screening based on the Cole criteria, 581 patients were selected and re-examined, and amplification techniques were performed. After reviewing the complementary exams, 102 patients were diagnosed with dactylolysis spontanea or ainhum. Soft-tissue constriction was the most frequently presented radiological sign on the initial screening. Kurtosis at the digit plantar fold and marked rotation of the fifth toe were normal findings in asymptomatic patients. Demographics, comorbidities, and radiological findings were analyzed in the selected population. Associated diseases occurring in these patients appeared to have no specific etiologic correlation with ainhum. African Americans and the dark-skinned population are affected exclusively by this condition, presumably due to the fibrogenic tendency of these individuals. Early diagnosis and accurate staging of ainhum are facilitated by radiological examination of the feet. The findings suggest that this condition is underdiagnosed and overlooked because its low prevalence and variable clinical presentations that might mimic more common etiologies, including localized trauma.  相似文献   
82.
Coeliac disease has been associated with a variety of neurological conditions, most frequently cerebellar ataxia and peripheral neuropathy. To date, chorea has not been associated with coeliac disease. We present the case histories of 4 individuals with coeliac disease and chorea (4 women, average age of onset of chorea 61 years). Unexpectedly, most of these patients showed a notable improvement in their motor symptoms after the introduction of a gluten-free diet.  相似文献   
83.
84.
85.
The effect of the experimental antiepileptic drug zonisamide (1,2-benzisoxazole-3-methanesulfonamide, ZNS) on the trigeminal complex of cats was compared with the effect of established antiepileptic drugs. Intravenous administration of 10-40 mg/kg ZNS significantly depresses descending excitatory mechanisms, as well as segmental and descending inhibitory mechanisms, but has only a minor effect on segmental excitatory mechanisms. This spectrum of activity is similar to that of valproate, and suggests that ZNS should also be a broad-spectrum antiepileptic drug. In agreement with our experimental observations, it has been found that ZNS is effective against complex partial, generalized tonic clonic, and myoclonic seizures. The antiepileptic profile of ZNS in conventional screening tests resembles that of carbamazepine (CBZ) and phenytoin. However, CBZ exacerbates rather than prevents myoclonic seizures. Our experimental model thus provides a more accurate prediction of ZNS's clinical spectrum of activity. The relationship of these findings to the mechanism of action of antiepileptic drugs is discussed.  相似文献   
86.
87.
Standardised epidemiological caries assessments used in oral health surveys have been shown to be poor at predicting whether a tooth surface will be treated restoratively when a patient visits a dentist. However, it has been argued that oral health surveys may be more relevant in determining needs at the level of an individual or groups of individuals. The objective of this study was to determine the discriminatory power of visual caries assessments at two thresholds (D1 & D3) in adolescents of average age 12.1 years to predict experience of dentinal caries 3 years later or the experience of restorative treatment (not re‐treatment) during the 3‐year period. The data was derived from a prospective 3‐year longitudinal study in which the dental care provided by 41 dentists for 403 adolescents was monitored. Dental caries experience was monitored by annual standardised assessments of caries undertaken by a single trained examiner. ROC analysis showed that caries assessed visually at the D1 threshold in 12‐year‐olds was a better predictor (P < 0.001) of experiencing some dentinal caries after 3 years (Az = 0.781) than was caries assessed visually at D3 threshold in 12‐year‐olds (Az = 0.670). Assessing caries visually at either the D1 or the D3 threshold had no discriminatory power for predicting whether an individual would experience some restorative treatment during the ensuing 3‐year period (Az for D1 = 0.507; Az for D3 = 0.518).  相似文献   
88.
89.
The behavior of the free acid and ammonium salt of maduramicin towards heat and alcohols is examined. In refluxing lower alcohols the free acid material is decarboxylated. In addition a bisketal decarboxylated compound as well as an A-ring monoketal decarboxylated derivative are formed. Heating the ammonium salt of the ionophores in suspension in water, or dissolved in inert solvents such as heptane or xylene can cause decarboxylation as well as concomitant dehydration of the F-ring. Reaction of dansyl chloride with the free acid of maduramicin can cause dehydration of the B-ring under very mild conditions.  相似文献   
90.
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