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   14689篇
  免费   813篇
  国内免费   136篇
耳鼻咽喉   189篇
儿科学   318篇
妇产科学   191篇
基础医学   2233篇
口腔科学   354篇
临床医学   1341篇
内科学   2814篇
皮肤病学   540篇
神经病学   1145篇
特种医学   690篇
外科学   2073篇
综合类   72篇
一般理论   2篇
预防医学   640篇
眼科学   379篇
药学   1338篇
中国医学   187篇
肿瘤学   1132篇
  2023年   74篇
  2022年   248篇
  2021年   512篇
  2020年   280篇
  2019年   362篇
  2018年   407篇
  2017年   343篇
  2016年   489篇
  2015年   652篇
  2014年   757篇
  2013年   835篇
  2012年   1311篇
  2011年   1188篇
  2010年   738篇
  2009年   646篇
  2008年   842篇
  2007年   881篇
  2006年   742篇
  2005年   675篇
  2004年   558篇
  2003年   452篇
  2002年   422篇
  2001年   320篇
  2000年   299篇
  1999年   225篇
  1998年   83篇
  1997年   74篇
  1996年   58篇
  1995年   63篇
  1994年   46篇
  1993年   33篇
  1992年   87篇
  1991年   71篇
  1990年   84篇
  1989年   82篇
  1988年   69篇
  1987年   58篇
  1986年   64篇
  1985年   55篇
  1984年   37篇
  1983年   39篇
  1982年   22篇
  1981年   33篇
  1980年   26篇
  1979年   38篇
  1978年   45篇
  1977年   31篇
  1975年   33篇
  1974年   27篇
  1973年   21篇
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
41.
42.
BACKGROUND: Practitioners are being encouraged to base their clinical practice on research evidence. In order to do this, they must be aware of and use the sources of evidence. METHODS: A questionnaire survey was undertaken to establish GPs' awareness of research evidence in their clinical practice and, in fundholding practices, its influence on purchasing plans. Questionnaires were sent to 360 lead fundholders in North Thames Region and 440 of a random sample of the remaining general practitioners in the region for comparison. RESULTS: Questionnaires were returned by 62% of lead fundholders and 63% of GPs in the random sample. There was limited use of the electronic sources of clinical effectiveness. There was greater reported awareness of published sources of research evidence and fundholding GPs were significantly more likely to have referred to publications summarizing research evidence. CONCLUSIONS: GPs seem to make more use of published clinical effectiveness sources than the electronic databases. Consequently, they need educational and technical support if they are to make full use of the available sources of research evidence available in other media.   相似文献   
43.
Sensitization of striatal N-methyl- -aspartate receptors (NMDAR) has been linked to events leading to the motor response changes associated with the administration of dopaminomimetics to parkinsonian animals and patients. To determine whether tyrosine phosphorylation of NMDAR subunits contributes to the apparent long-term enhancement in synaptic efficacy of these receptors, we examined the effect of unilateral nigrostriatal dopamine system ablation with 6-hydroxydopamine followed by twice-daily treatment with -DOPA on the phosphorylation state of rat striatal NR2A and NR2B subunits. Three weeks of intermittent -DOPA administration produced a shortening in the duration of the rotational response to dopaminergic challenge and other changes mimicking those occurring in patients with Parkinson's disease. Concurrently, tyrosine phosphorylation of NR2A and especially of NR2B subunits increased ipsilateral to the lesion (20±5% and 46±7% of intact striatum, respectively; p<0.01) without attendant changes in subunit protein levels. Selective blockade of NR2B subunits with ACEA 10-1244, but not of NR2A subunits with MDL 100,453, reversed the -DOPA-induced response alterations. The intrastriatal injection of a tyrosine kinase inhibitor, genistein, at a dose (2.0 μg) that normalized the response shortening, attenuated the NR2A and NR2B phosphorylation increase by about 12% and 24%, respectively (p<0.01). Taken together, these results suggest that augmented tyrosine phosphorylation of NR2B subunits, alone or in combination with the smaller rise in NR2A subunit phosphorylation, contributes to the apparent enhancement in striatal NMDAR sensitivity and thus to the plastic alterations in dopaminergic responses in -DOPA-treated parkinsonian rats.  相似文献   
44.

Background  

Statin-related skeletal muscle disorders range from benign myalgias – such as non-specific muscle aches or joint pains without elevated serum creatinine kinase (CK) concentration – to true myositis with >10-fold elevation of serum CK, to rhabdomyolysis and myoglobinuria. The genetic basis of statin-related muscle disorders is largely unknown. Because mutations in the COQ2 gene are associated with severe inherited myopathy, we hypothesized that common, mild genetic variation in COQ2 would be associated with inter-individual variation in statin intolerance. We studied 133 subjects who developed myopathy on statin monotherapy and 158 matched controls who tolerated statins without incident or complaint.  相似文献   
45.
OBJECTIVES: To analyze the clinical characteristics and treatment results between bilateral (bi-) and unilateral (uni-) sudden sensorineural hearing loss (SSNHL). STUDY DESIGN AND SETTING: A retrospective study. METHODS: Three hundred twenty-four patients with SSNHL were classified into two groups; simultaneous bi-SSNHL (n = 16) and uni-SSNHL (n = 308). We compared clinical characteristics, medical history, hearing level, and treatment results between the 2 groups. RESULTS: The incidence of bi-SSNHL was 4.9 percent of overall patients with SSNHL. Bi-SSNHL occurs more commonly in patients of older age, with preexisting diabetes mellitus, and lipid panel abnormalities compared with uni-SSNHL. Ten patients (62.5%) in the bi-SSNHL group showed hearing recovery in 1 or both ears compared with 56.5 percent of patients with uni-SSNHL. Only 12 (37.5%) of all 32 ears recovered in bi-SSNHL, which was significantly lower than in uni-SSNHL. CONCLUSION: Bi-SSNHL has a very low incidence and lower recovery rate than uni-SSNHL. Recognition of similarities and differences between bilateral and unilateral SSNHL can help in counseling and managing the patients.  相似文献   
46.
47.
48.
49.
"What is growth anyway? Can one talk about positive growth in childhood, neutral growth in maturity, and negative growth in old age?" Our goal is to help promote normal positive growth in infants and children. To achieve this, we must be cognizant of the morphologic changes of both normal and abnormal bone formation as they are reflected in the radiographic image of the skeleton. The knowledge of the various causes and the pathophysiologic mechanisms of the disturbances of bone growth and development allows us to recognize the early radiographic manifestations. Endocrine and metabolic disorders affect the whole skeleton, but the early changes are best seen in the distal ends of the femurs, where growth rate is most rapid. In skeletal infections and in some vascular injuries two-or three-phase bone scintigraphy supercedes radiography early in the course of the disease. MRI has proved to be very helpful in the early detection of avascular bone necrosis, osteomyelitis, and tumor. Some benign bone tumors and many bone dysplasias have distinct and diagnostic radiographic findings that may preclude further studies. In constitutional diseases of bone, including chromosomal aberrations, skeletal surveys of the patient and all family members together with biochemical and cytogenetic studies are essential for both diagnosis and genetic counseling. Our role is to perform the least invasive and most informative diagnostic imaging modalities that corroborate the biochemical and histologic findings to establish the definitive diagnosis. Unrecognized, misdiagnosed, or improperly treated disturbance of bone growth can result in permanent deformity usually associated with disability.  相似文献   
50.
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