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   27501篇
  免费   2468篇
  国内免费   75篇
耳鼻咽喉   316篇
儿科学   655篇
妇产科学   474篇
基础医学   3563篇
口腔科学   649篇
临床医学   3114篇
内科学   6182篇
皮肤病学   327篇
神经病学   2449篇
特种医学   1003篇
外国民族医学   1篇
外科学   3725篇
综合类   639篇
一般理论   25篇
预防医学   2463篇
眼科学   718篇
药学   2014篇
中国医学   48篇
肿瘤学   1679篇
  2021年   364篇
  2020年   203篇
  2019年   381篇
  2018年   387篇
  2017年   316篇
  2016年   352篇
  2015年   441篇
  2014年   645篇
  2013年   1052篇
  2012年   1317篇
  2011年   1397篇
  2010年   785篇
  2009年   759篇
  2008年   1310篇
  2007年   1524篇
  2006年   1531篇
  2005年   1493篇
  2004年   1492篇
  2003年   1425篇
  2002年   1417篇
  2001年   565篇
  2000年   547篇
  1999年   580篇
  1998年   379篇
  1997年   340篇
  1996年   315篇
  1995年   322篇
  1994年   290篇
  1993年   279篇
  1992年   412篇
  1991年   413篇
  1990年   348篇
  1989年   348篇
  1988年   354篇
  1987年   334篇
  1986年   320篇
  1985年   322篇
  1984年   357篇
  1983年   319篇
  1982年   342篇
  1981年   325篇
  1980年   262篇
  1979年   253篇
  1978年   264篇
  1977年   247篇
  1976年   265篇
  1975年   222篇
  1974年   223篇
  1973年   259篇
  1972年   182篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
111.
112.
Early identification of disabilities enables early intervention by occupational therapists and other health professionals. Because the number of children who can be seen in therapy is limited, it is important to be able to identify those infants most likely to have deficits at a later age. Therefore, it is necessary to study and understand the relationship between infants' scores on early developmental assessments and later developmental outcomes. The purpose of this study was to determine the extent to which scores on the Bayley Scales of Infant Development (BSID) during the first 2 years of life are related to motor and cognitive performance at 4 1/2 years for a sample of children identified at birth as biologically high risk. This retrospective study involved 70 children who were evaluated at corrected ages of 4 months, 1 year, 2 years, and 4 1/2 years. The 4-month BSID Mental and Motor Scale scores did not relate significantly to later cognitive motor performance. In contrast, the 12-month BSID Mental Scale scores related significantly to preschool scores on both the motor and cognitive measures. However, the 24-month BSID Mental Scale scores related significantly only to scores on the preschool cognitive measures. Though significant, these correlation coefficients had small magnitudes. Thus, therapists should be cautious about using BSID testing at 4 months, 1 year, and 2 years when attempting to predict later preschool performance.  相似文献   
113.
测量大脑     
事物的本质人类的智力是虚幻的,是难以受到约束的。甚至难以给它一个定义。智力可以用能力来解释吗?和记忆力有关吗?它和语言有关吗?还是数学?还是和上面的都有关系呢?只要你说你只是不能衡量智力,许多人会离去。为了使一个人  相似文献   
114.
1. Conscious, Long Evans rats (n = 10), chronically instrumented for the measurement of regional haemodynamics, were studied on 3 consecutive experimental days to assess responses to angiotensin II (AII) (125 pmol kg-1, i.v.) and noradrenaline (1 nmol kg-1, i.v.) in the absence and presence of the AT2-receptor antagonist, PD 123319 (10 mg kg-1, i.v.) (day 1), the AT1-receptor antagonist, EXP 3174 (1 mg kg-1, i.v.) (day 2), and PD 123319 (10 mg kg-1, i.v.) given 24 h after EXP 3174 (day 3). 2. In naive rats (day 1), PD 123319 did not antagonize the haemodynamic effects of AII or noradrenaline. EXP 3174 (day 2) caused a marked, prolonged blockade of the haemodynamic effects of AII but not those of noradrenaline. Twenty four h after administration of EXP 3174 (day 3) there was still significant attenuation of the haemodynamic effects of AII. However, administration of PD 123319 at this time caused a further inhibition (lasting 1 h) of the effects of AII but not those of noradrenaline. 3. An identical 3 day protocol was used in a separate group of rats (n = 6) in which the AT2-receptor antagonist, PD 123177, was given instead of PD 123319, and the results were essentially the same, i.e., PD 123177 significantly attenuated the haemodynamic effects of AII but only when given 24 h after EXP 3174.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
115.
116.
Two discrete areas of the chick brain, the intermediate medial hyperstriatum ventrale (IMHV) and lobus parolfactorius (LPO), were found to have different functions during the formation of memory for a 1-trial peck-avoidance paradigm. Glutamate, ouabain, and emetine, known to disrupt short-, intermediate-, and long-term memory when injected into the IMHV, were injected into the cerebellum and LPO. All amnestic agents investigated produced amnesia when injected into the IMHV; only one of these agents produced amnesia when injected into the LPO, and none of the agents produced amnesia when injected into the cerebellum. The chick brain was also found to exhibit hemispheric asymmetries: The left IMHV and LPO were more sensitive to the amnestic agents than their corresponding right structure. From these data, hypotheses for the roles of these structures during memory are proposed.  相似文献   
117.
The duration of response to treatment with alefacept has been assessed in patients with moderate to severe chronic plaque psoriasis who responded to alefacept therapy in phase 2 and phase 3 clinical studies. In a phase 2 trial, duration of response was based on time to retreatment with alefacept. In two phase 3 studies, the more objective measure of maintenance of a ≥50% reduction from baseline Psoriasis Area and Severity Index (PASI 50) was used. Two patient subsets were analyzed: (1) those who achieved a PASI 75 at any time during the trials and (2) those who achieved a Physician Global Assessment of “clear” or “almost clear” at any time during the trials. Regardless of the criterion used or the route of alefacept administration (intravenous or intramuscular), the median duration of response to alefacept therapy ranged from 7 to 10 months across the three studies. Alefacept is a remittive therapy for psoriasis.  相似文献   
118.
119.
120.
Lipodermatosclerosis: review of cases evaluated at Mayo Clinic.   总被引:1,自引:0,他引:1  
BACKGROUND: Lipodermatosclerosis describes bound-down, sclerotic skin involving the lower extremities. OBJECTIVE: Our purpose was to describe the demographic and clinical features of patients with lipodermatosclerosis. METHODS: This was a retrospective study of patients presenting to Mayo Clinic between 1976 and 1998 with a diagnosis of lipodermatosclerosis. RESULTS: Of 97 patients, 84 (87%) were women. Mean age was 62 years (range, 25-88 years). Mean body mass index was 34.3 (range, 17.8-71.5). Clinical signs were bilateral involvement in 44 patients (45%), induration localized to a discrete plaque in 49 (51%), erythema in 69 (71%), hyperpigmentation in 57 (59%), ulceration in 13 (13%), concomitant edema in 69 (71%), and varicosities in 55 (57%). Vascular studies performed on 72 patients showed abnormalities in 49: deep venous incompetence in 33 (67%), calf muscle pump abnormality in 19 (39%), abnormal pulsatility in 10 (20%), and obstruction in 1 (2%). CONCLUSION: Lipodermatosclerosis was associated with female sex, middle age, high body mass index, and venous abnormalities.  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