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   27765篇
  免费   1817篇
  国内免费   82篇
耳鼻咽喉   226篇
儿科学   696篇
妇产科学   460篇
基础医学   3985篇
口腔科学   345篇
临床医学   2562篇
内科学   6438篇
皮肤病学   934篇
神经病学   2498篇
特种医学   806篇
外国民族医学   4篇
外科学   4190篇
综合类   270篇
一般理论   28篇
预防医学   1975篇
眼科学   505篇
药学   1672篇
  1篇
中国医学   57篇
肿瘤学   2012篇
  2022年   122篇
  2021年   346篇
  2020年   234篇
  2019年   382篇
  2018年   456篇
  2017年   300篇
  2016年   361篇
  2015年   428篇
  2014年   657篇
  2013年   987篇
  2012年   1458篇
  2011年   1629篇
  2010年   1123篇
  2009年   1266篇
  2008年   1664篇
  2007年   1707篇
  2006年   1693篇
  2005年   1794篇
  2004年   1644篇
  2003年   1564篇
  2002年   1545篇
  2001年   430篇
  2000年   363篇
  1999年   419篇
  1998年   399篇
  1997年   412篇
  1996年   297篇
  1995年   310篇
  1994年   263篇
  1993年   235篇
  1992年   319篇
  1991年   306篇
  1990年   277篇
  1989年   255篇
  1988年   227篇
  1987年   242篇
  1986年   239篇
  1985年   224篇
  1984年   218篇
  1983年   206篇
  1982年   235篇
  1981年   230篇
  1980年   189篇
  1979年   150篇
  1978年   135篇
  1977年   144篇
  1976年   114篇
  1975年   112篇
  1974年   103篇
  1973年   94篇
排序方式: 共有10000条查询结果,搜索用时 333 毫秒
11.
12.
13.
(1) The estrous cycle in the rat may be used to study recurrent changes in motor behaviors and motivation which are strongly related to cyclic hormonal and CNS changes. (2) The peak in motivated behaviors occurs during a sharply defined period on the night between proestrus and estrus and is evident in facilitated wheel-running, lordosis, and intracranial self-stimulation. (3) Behaviors without a clearly motivated character do not show an estrous cyclicity. (4) The estrous cyclic variation in intracranial self-stimulation was observed at a specific locus — the pars campacta of the substantia nigra. (5) A neurochemical link between sexually motivated behavior, wheel running and intracranial self-stimulation is suggested. This link is in part dopaminergic but is probably also activated by many other systems.  相似文献   
14.
15.
To determine whether the mouse loses bone with aging and whether the changes mimic those observed in human aging, we examined the changes in the tibial metaphysis and diaphysis in the male C57BL/6J mouse over its life span using microcomputed tomography (microCT). Cancellous bone volume fraction (BV/TV) decreased 60% between 6 weeks and 24 months of age. Loss was characterized by decreased trabecular number (Tb.N), increased trabecular spacing (Tb.Sp), and decreased connectivity. Anisotropy decreased while the structure model index increased with age. Cortical bone thickness increased between 6 weeks and 6 months of age and then decreased continuously to 24 months (-12%). Cortical bone area (Ct.Ar) remained constant between 6 and 24 months. Fat-free weight reached a peak at 12 months and gradually declined to 24 months. Total mass lost between 12 and 24 months reached 10%. Overall, the age-related changes in skeletal mass and architecture in the mouse were remarkably similar to those seen in human aging. Furthermore, the rapid early loss of cancellous bone suggests that bone loss is not just associated with old age in the mouse but rather occurs as a continuum from early growth. We conclude that the C57BL/6J male mouse maybe a useful model to study at least some aspects of age-related bone loss in humans.  相似文献   
16.
17.
Reported herein is a case of obsessive–compulsive disorder with persistent and distressing musical obsessions along with other symptoms. Advanced source analysis of electroencephalographic data indicated high spectral power over the bifrontal region. The musical symptoms were resistant to pharmacotherapy but there was some reduction in frequency and duration of musical obsessions with thought-stopping technique.  相似文献   
18.
19.
ImmunoCyt/uCyt is a fluorescent test combining three monoclonal antibodies. In this study, it has been tested as a complement to cytology in the detection of urothelial carcinoma in urine. It has been performed simultaneously with standard cytology and cystoscopy on 870 urine analyses from one hospital. In 136 cases, one or more bladder tumors were found. Overall sensitivity of cytology, ImmunoCyt/uCyt and combined analyses reached 29, 74 and 84%, respectively, and overall specificity was 98, 62 and 61%. The negative predictive value of cytology, ImmunoCyt/uCyt and both analyses was 88, 93 and 95%, respectively, and the positive predictive value was 70, 26 and 29%. The sensitivity of cytology for low malignant potential neoplasms, low- and high-grade papillary carcinomas was 6, 18 and 53%, while it reached 71, 79 and 93% when combined with ImmunoCyt/uCyt. The sensitivity of cytology for stages Ta, T1, T2 and over and Tis tumors was 12, 67, 47 and 50%, while it reached 78, 83, 79 and 100% when combined with ImmunoCyt/uCyt. In the absence of tumor on cystoscopy but with positive ImmunoCyt/uCyt, 18% of patients developed a tumor, 2-6 months later. Of the 109 cases diagnosed as suspicious for malignancy by cytology, a tumor was present in 30 cases and ImmunoCyt/uCyt was positive in 22 (73%) of them. In conclusion, ImmunoCyt/uCyt may be used to postpone cystoscopies in patients followed for bladder cancer and may help to save cytologist and pathologist screening time.  相似文献   
20.
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