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   7893篇
  免费   1176篇
  国内免费   31篇
耳鼻咽喉   131篇
儿科学   267篇
妇产科学   192篇
基础医学   720篇
口腔科学   104篇
临床医学   1561篇
内科学   1525篇
皮肤病学   159篇
神经病学   963篇
特种医学   263篇
外科学   1212篇
综合类   101篇
一般理论   2篇
预防医学   753篇
眼科学   137篇
药学   450篇
中国医学   2篇
肿瘤学   558篇
  2023年   159篇
  2022年   66篇
  2021年   175篇
  2020年   232篇
  2019年   135篇
  2018年   291篇
  2017年   236篇
  2016年   272篇
  2015年   243篇
  2014年   376篇
  2013年   454篇
  2012年   341篇
  2011年   309篇
  2010年   322篇
  2009年   393篇
  2008年   331篇
  2007年   291篇
  2006年   341篇
  2005年   278篇
  2004年   240篇
  2003年   209篇
  2002年   207篇
  2001年   238篇
  2000年   208篇
  1999年   216篇
  1998年   100篇
  1997年   101篇
  1996年   106篇
  1995年   91篇
  1994年   51篇
  1993年   49篇
  1992年   128篇
  1991年   160篇
  1990年   124篇
  1989年   113篇
  1988年   104篇
  1987年   110篇
  1986年   111篇
  1985年   97篇
  1984年   67篇
  1983年   80篇
  1982年   50篇
  1981年   48篇
  1979年   80篇
  1978年   63篇
  1977年   53篇
  1976年   47篇
  1975年   58篇
  1974年   71篇
  1973年   44篇
排序方式: 共有9100条查询结果,搜索用时 46 毫秒
81.
Properties of a filamentous virus of the honey bee (Apis mellifera)   总被引:2,自引:0,他引:2  
An ellipsoidal particle, measuring 450 x 150 nm, from honey bees comprises a nucleocapsid measuring 3000 x 40 nm, containing double-stranded DNA with a molecular weight of approximately 12 x 10(6), which is coiled within a membrane. The buoyant densities in CsCl of the whole particle, nucleocapsid, DNA and DNA with ethidium bromide are 1.28, 1.36, 1.71 and 1.61 g/ml, respectively. The particle contains about 12 proteins, with molecular weights ranging from 13,000 to 70,000, which are distributed approximately equally between the membrane and the nucleocapsid.  相似文献   
82.
The clinical manifestations and psychomotor development of five patients with mucolipidosis IV (MLIV) from three Ashkenazi-Jewish families are reported. The presenting symptoms were hypotonia, developmental delay, corneal clouding, and puffy eyelids. Four of the patients had convergent strabismus and none progressed beyond a developmental age of 15 months. One patient died of aspiration at 17 years while the oldest patient entered puberty at 20 years, developed a coarse face at 30 years, and is now 32 years old. Histopathological studies in four patients showed storage changes characteristic of MLIV.  相似文献   
83.
84.
In 35 monkeys attempts were made to produce localized unilateral lesions in individual vestibular nuclei in order to study vestibular projections to nuclei of the extraocular muscles. Portions of the medial, superior and inferior vestibular nuclei were destroyed selectively; lesions in Deiters' nucleus involved small portions of either the superior or inferior vestibular nuclei. Fiber degeneration was studied by the Nauta-Gygax technic. Exclusively ascending fibers from the superior vestibular nucleus project to ipsilateral extraocular nuclei. Ascending fibers from the inferior vestibular arise only from rostral portions of the nucleus, are not numerous and pass to all extraocular nuclei. The medial vestibular nucleus projects ascending fibers via the MLF bilaterally, asymmetrically and differentially to all extraocular nuclei. Prominent projections pass to: (a) the contralateral trochlear nucleus, and (b) the contralateral intermediate cell column and the ipsilateral ventral nucleus of the oculomotor complex. Ascending fibers from Deiters' nucleus, arising only from ventral portions of the nucleus, project primarily to: (a) the contralateral abducens and trochlear nuclei, and (b) specific asymmetrical portions of the oculomotor complex. Ascending vestibular fibers from the medial and lateral vestibular nuclei appear capable of mediating all patterned eye movements resulting from stimulation of ampullary nerves from individual semicircular canals. Vestibular projections to nuclei of the extraocular muscles are most abundant to those nuclei innervating muscles whose primary functions concern horizontal and rotatory eye movements.  相似文献   
85.
86.
Features associated with suicide attempts in recurrent major depression   总被引:1,自引:0,他引:1  
Sixty-seven individuals with recurrent major depression and a history of suicide attempts are compared with 163 individuals with recurrent major depression and no history of suicide attempts. The groups are contrasted on demographic features, clinical course, severity of depression, co-morbidity, and acute symptom profiles. Patients with a history of attempts are distinguished from non-attempters by suicidal ideation, marital isolation, neurovegetative signs, feelings of failure, and co-morbid alcoholism or bipolar II disorder. Logistic regression analysis using a model which included a portion of the significant variables correctly classified 77% of the cases. These findings are discussed with reference to prediction of suicide attempts in individuals with major affective disorder.  相似文献   
87.
88.
A competitive type-specific enzyme-linked immunosorbent assay (ELISA) for herpes simplex virus type 2 (HSV-2) antibody was developed using an infected cell antigen and a monoclonal antibody to glycoprotein G-2. This assay has been validated for use for epidemiological studies using a large panel of sera collected in rural Uganda and a panel of 143 sera characterised previously by Western blotting, the 'gold standard' for HSV type-specific serology. This evaluation was found to have a sensitivity of 96% and a specificity of 91% in comparison with Western blot on 143 sera from clinic patients. The ELISA had a sensitivity of 93% and a specificity of 91% in comparison with Western blot on 495 sera collected in Uganda. The assay showed good reproducibility and a low percentage of sera gave equivocal results, indicating its suitability for epidemiological studies.  相似文献   
89.
Epidemiologic modeling has provided both researchers and students with a means of studying complex disease processes as well as making intervention recommendations to decision makers. To develop more than the most elementary model, however, it has become necessary to be well versed in a computer programming language. While this has deterred many modelers in the past, with microcomputers it is now possible to develop even complex models without significant investment of time spent in learning a computer language. In addition to being affordable, many microcomputers offer "canned" spreadsheet packages which are readily adapted for epidemiologic modeling. To demonstrate this, two models were developed and run using a microcomputer spreadsheet package: 1) the classic Reed-Frost model, and 2) a modified Reed-Frost model with two intermixing subpopulations.  相似文献   
90.
The ongoing global pandemic caused by coronavirus disease has once again demonstrated the role of the family Coronaviridae in causing human disease outbreaks. Because severe acute respiratory syndrome coronavirus 2 was first detected in December 2019, information on its tropism, host range, and clinical manifestations in animals is limited. Given the limited information, data from other coronaviruses might be useful for informing scientific inquiry, risk assessment, and decision-making. We reviewed endemic and emerging infections of alphacoronaviruses and betacoronaviruses in wildlife, livestock, and companion animals and provide information on the receptor use, known hosts, and clinical signs associated with each host for 15 coronaviruses detected in humans and animals. This information can be used to guide implementation of a One Health approach that involves human health, animal health, environmental, and other relevant partners in developing strategies for preparedness, response, and control to current and future coronavirus disease threats.  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