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   32716篇
  免费   2303篇
  国内免费   109篇
耳鼻咽喉   258篇
儿科学   1321篇
妇产科学   975篇
基础医学   4454篇
口腔科学   403篇
临床医学   4208篇
内科学   6282篇
皮肤病学   632篇
神经病学   3487篇
特种医学   729篇
外科学   3153篇
综合类   341篇
一般理论   32篇
预防医学   3869篇
眼科学   561篇
药学   1921篇
中国医学   56篇
肿瘤学   2446篇
  2024年   39篇
  2023年   253篇
  2022年   462篇
  2021年   920篇
  2020年   577篇
  2019年   953篇
  2018年   1025篇
  2017年   717篇
  2016年   828篇
  2015年   861篇
  2014年   1219篇
  2013年   1797篇
  2012年   2657篇
  2011年   2709篇
  2010年   1509篇
  2009年   1243篇
  2008年   2170篇
  2007年   2340篇
  2006年   2267篇
  2005年   2145篇
  2004年   1910篇
  2003年   1766篇
  2002年   1692篇
  2001年   228篇
  2000年   175篇
  1999年   220篇
  1998年   319篇
  1997年   284篇
  1996年   216篇
  1995年   191篇
  1994年   152篇
  1993年   188篇
  1992年   111篇
  1991年   91篇
  1990年   67篇
  1989年   69篇
  1988年   79篇
  1987年   41篇
  1986年   48篇
  1985年   42篇
  1984年   53篇
  1983年   55篇
  1982年   52篇
  1981年   47篇
  1980年   52篇
  1979年   36篇
  1978年   38篇
  1977年   25篇
  1975年   21篇
  1973年   19篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
ONE OF THE RISK FACTORS FOR HUMAN PAPILLOMAVIRUS (HPV) INFECTION and subsequent lower genital tract neoplasias and cancers is impaired cell-mediated immunity. HIV-positive women with severe immunosuppression are 5 times more likely than HIV-negative women to have lower genital tract neoplasias. A corresponding increase in the risk of invasive vulvar and anal cancers, but not of cervical cancer, has also been observed among HIV-positive women. Treatment failure and recurrence of neoplasia occur much more frequently among HIV-positive than among HIV-negative women. In this review, we discuss recent advances in the understanding of the relation between HIV and HPV coinfection and the development of lower genital tract neoplasias and cancers in women. In addition, we present strategies for monitoring and treating noninvasive and invasive neoplasias of the lower genital tract in HIV-positive women.  相似文献   
92.
93.
94.
95.
One biceps muscle of 8 patients with Duchenne muscular dystrophy was injected at 55 sites with a total of 55 million viable, purified, and contamination-free normal myoblasts (myoblast transfer). The other biceps of each patient was injected with a placebo to serve as a control. The procedure was blinded to the patients, parents, and investigators. Myoblasts derived from a biopsy specimen of the fathers were cultured and purified under strict conditions and carefully screened for microbial contamination. All patients received cyclophosphamide for immunosuppression for 6 or 12 months. No serious complications were observed after myoblast transfer, indicating that the procedure is safe. The overall therapeutic efficiency of myoblast transfer was poor as judged by the results in maximal voluntary force generation, dystrophin content of the muscle, magnetic resonance imaging of the muscle, and the lack of donor-derived DNA and dystrophin messenger RNA in the injected muscle. An improved efficiency of the take of myoblasts might be achieved by using younger cells and injecting the myoblasts with a myonecrotic agent (to increase the prevalence of regeneration) and a basal laminal fenestrating agent.  相似文献   
96.
ABSTRACT: The Dartmouth Health Promotion Study was a longitudinal, quasi-experimental field study with a qualitative research arm, designed to learn whether coordinating school health instruction, health services, and a healthful environment enhanced the program's effect on the heart health and mental health of children. The research strategy — the Coordinated Approach — was applied to approximately 300 children in each of two cohorts in grades four to six attending nine trial schools; a further 600 children attended 10 comparison schools in Dartmouth and nine distal comparison schools. Although the qualitative analysis demonstrated that positive feelings were engendered in most areas of the study, when either the classroom or the individual was used as the unit of analysis, the Coordinated Approach did not have a more favorable effect on the heart or mental health of children than did the standard school health program. Thus, the effect of an existing school health program was not directly enhanced through coordinating its components.  相似文献   
97.
The dietary intake of homeless males sleeping rough in Central London   总被引:1,自引:0,他引:1  
Data concerning the food and beverage intake (including alcohol) of 79 males, aged 19–50 years, sleeping rough in Central London, who did not appear to be under the influence of drink, drugs or suffering from mental illness were collected by prompted 24-h recall and food-frequency questionnaire (FFQ). The source of food was noted and the subjects were asked about food availability and food needs. The group had intakes significantly lower than Dietary Reference Values (DRV) for the UK for energy, carbohydrate, non-starch polysaccharides (NSP), folate, zinc and magnesium. Significantly higher values were seen for protein, fat, vitamin B12, calcium and iron. Alcohol intake was higher than that assumed to approximate current intakes of the UK population. Mean macronutrient intakes for the group were similar to means for British adult men (OPCS, 1990), only protein and NSP were significantly lower. The FFQ showed very low consumption/week of fruit, vegetables, salad, fruit juice and wholewheat/brown products. Organized charities provided the major source of food energy for the group as a whole. Self-supplied sources provided the major source of total energy. It is suggested that the group may benefit from an increase in dietary fibre and energy, with an increase in the proportion of energy supplied by carbohydrate and a reduction in energy from fat and alcohol. A varied supply of food and hot meals during weekends as well as during the week may benefit the group both aesthetically and nutritionally. It may be advisable to increase the supply of wholemeal/brown bread, fruits, vegetables and salad foods without decreasing the energy content of the food available.  相似文献   
98.
99.
Low amplitude pulses of estradiol-17β (E2-17β) are more effective than large single bolus injections or constant exposure to E2-17β in inducing progesterone-facilitated sex behavior in female rats and guinea pigs. The present study examined whether the increased responsiveness to E2-17β is due to an increase in the number of estrogen receptors in the estrogen receptor rich areas of the hypothalamus and amygdala. Initial studies examined the rapid effects (20 min) of a high dose of E2-17β (50 μg) on estrogen receptor immunostaining using either the H222 antibody or the ER 21 antiserum. ER 21 immunostaining was not affected by the E2-17β treatment suggesting that it binds to both occupied and unoccupied estrogen receptors. Therefore the ER 21 antiserum was used to characterize the regulation of estrogen receptor immunoreactivity (ER-IR) by E2-17β. ER-IR was examined for 48 h and serum E2-17β for 24 h following a 2 μg s.c. injection of E2-17β (a dose similar to that used in multiple pulse paradigms). Serum E2-17β peaked 15 to 30 min following the injection and returned to baseline values by 1 h. In all but one area maximal suppression of ER-IR occurred at 12 h. In summary, 1) decreases in estrogen receptor immunoreactivity following E2-17β are consistent with studies in which estrogen receptors were assayed by binding assays and estrogen receptor mRNA was determined by in situ hybridization; 2) the ER 21 antiserum is able to detect both occupied and unoccupied estrogen receptors and 3) H222 immunoreactivity is influenced by the presence of E2-17β, so that the level of H222-IR is a reflection of ligand/receptor binding dynamics. The data suggest that up-regulation of estrogen receptors does not account for the increase in behavioral sensitivity which is observed following multiple pulses of E2-17β.  相似文献   
100.
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