首页 | 官方网站   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   5762篇
  免费   367篇
  国内免费   14篇
医药卫生   6143篇
  2023年   38篇
  2022年   46篇
  2021年   202篇
  2020年   137篇
  2019年   160篇
  2018年   196篇
  2017年   116篇
  2016年   143篇
  2015年   147篇
  2014年   252篇
  2013年   285篇
  2012年   367篇
  2011年   365篇
  2010年   213篇
  2009年   180篇
  2008年   250篇
  2007年   245篇
  2006年   232篇
  2005年   225篇
  2004年   186篇
  2003年   162篇
  2002年   142篇
  2001年   142篇
  2000年   113篇
  1999年   112篇
  1998年   46篇
  1997年   32篇
  1996年   42篇
  1995年   28篇
  1994年   41篇
  1993年   35篇
  1992年   85篇
  1991年   91篇
  1990年   93篇
  1989年   77篇
  1988年   69篇
  1987年   79篇
  1986年   58篇
  1985年   61篇
  1984年   64篇
  1983年   46篇
  1982年   63篇
  1981年   72篇
  1980年   70篇
  1979年   55篇
  1978年   33篇
  1977年   26篇
  1976年   32篇
  1973年   31篇
  1970年   26篇
排序方式: 共有6143条查询结果,搜索用时 15 毫秒
71.
The study aim was to examine the effect on birth spacing of a prior female child's birth. The study site was a rural health center under observation by staff from the Dayanand Medical College in Ludhiana, India. The sample included 73 pregnant women who were grouped by the sex of the preceding child. The results showed that the average birth interval was significantly shorter for women with a preceding birth of a female child. The average interval in weeks was 90.73 weeks + or - 54.46 weeks for the 41 women who had a prior girl child compared to 133.68 weeks for the male child. When the female child was at a parity of one the birth interval averaged 73.36 weeks, compared to 137.2 weeks for a prior parity of one male child. At parity of two, the average birth interval was 106.2 for a prior girl child and 144.38 for a prior male child. At a parity of three, the average birth interval was 88.22 weeks for a prior girl child and 96.5 weeks for a prior male child. At a parity of four, the average birth interval was 87.66 weeks for a prior girl child and 46.0 weeks for a prior male child. The significant effect of having a prior girl child was evident only at a parity of one. The intervals at a parity of two and three were shorter for girls but not significantly different. The recommendation was that young women and women with low parity be targeted for family planning in order to lengthen the birth interval, regardless of the desire for sons.  相似文献   
72.
Assay of hexosaminidase A and B enzymes in four cases with developmental regression and cherry red spot on fundus examination confirmed that three cases had Tay-Sachs disease, and one case had Sandhoff disease. Prenatal diagnosis was carried out by hexosaminidase enzyme assay in amniotic fluid and cells in one family, and chorionic villus sample in the second family. The fetus was diagnosed to be unaffected in one, and affected in the other family. Assay of hexosaminidase A and B is useful for specific diagnosis of GM2 gangliosidosis, and for prenatal diagnosis to reduce the burden of these disorders.  相似文献   
73.
Of 613 children evaluated in a village in Haryana 94 (15.3%) were observed to have chronic suppurative otitis media (CSOM). Fifty eight (61.7%) children had hearing impairment. CSOM contributed to 71.6% of the hearing impaired (58/81). On analysis of association of CSOM with literacy and socio-economic status of mothers, and age, sex, and upper respiratory tract infections (URI) in children positive correlation was observed only with URIs (P<0.001). Literacy and socio-economic status of the mothers did not correlate significantly with knowledge about treatment seeking, and ear cleaning practices, probably due to the narrow range of incomes and literacy levels. An intervention program consisting of play, demonstrations, health charts and slogans, and aural cleaning and antibiotic drops was introduced.  相似文献   
74.
Methods of assessing occupational exposure to diesel exhaust were evaluated in a railroad work environment. The American Conference of Governmental Industrial Hygienists (ACGIH)-recommended elemental carbon and respirable combustible dust methods of sampling and analysis for assessing diesel exhaust were included in the study. A total of 215 personal and area samples were collected using both size-selective (nylon cyclone and Marple) and non-size-selective samplers. The results demonstrate that the elemental carbon method is suitable for the railroad environment and the respirable combustible dust method is not. All elemental carbon concentrations measured were below the proposed ACGIH Threshold Limit Value (TLV) of 0.15 mg/m3. The concentrations of oxides of nitrogen (nitric oxide and nitrogen dioxide) were also found to be below their respective TLVs. There is no correlation between elemental carbon or respirable combustible dust and the oxides of nitrogen. The elemental carbon as fraction of total carbon is about 13 percent, except for onboard locomotives where it is about 24 percent. Comparison of elemental carbon and respirable combustible dust measurements showed consistent relationships for most sampling locations, with respirable combustible dust concentrations 12 to 53 times higher than the elemental carbon levels.  相似文献   
75.
76.
77.
PURPOSE: To analyze the clinical presentation and outcome of treatment for globe perforation secondary to peri-bulbar anaesthesia. METHODS: Eight patients (3 females and 5 males) aged 66-84 years were included in the study. Ocular perforations were suspected in 3 cases before or during surgery, in 4 cases diagnosis was established within one week and in one case at 3 weeks. Three patients underwent indirect argon laser photocoagulation to seal the retinal break, one patient had cryotherapy, 3 patients underwent a pars plana vitrectomy with fluid gas exchange and endo-laser; and one patient refused any further treatment. RESULTS: The final visual acuity after a mean follow up of 14 months was better than 6/9 in 2 patients, between 6/9-6/12 in 4 patients, and perception of light in 2 patients. CONCLUSION: If diagnosed early and treated adequately, a majority of patients with globe perforation during periocular anaesthetic could be saved.  相似文献   
78.
PURPOSE/BACKGROUND: Penetrating keratoplasty is the logical solution for the management of corneal opacities. In situations such as in Papua New Guinea, where donor corneal tissue is scarce and corneal opacities are plenty, an alternative procedure for the management of corneal opacities in the form of ipsilateral rotational autokeratoplasty was considered. METHODS: In the present prospective study, ipsilateral rotational autokeratoplasty was performed in 17 eyes over a 2 year period in a general hospital.The patient's cornea was trephined eccentrically and the corneal opacity was dialed out of the visual axis and was replaced by clear peripheral cornea. RESULTS: Most opacities were leucomata (76.4%). The average size of the opacity was 5.1 mm and the corneal button size was 7 mm.A final visual acuity of 6/18 or better was obtained in 64.7% of cases (at 12 months). No significant postoperative complications were encountered. No complex formula was needed to calculate the size of the button and, by simply adding 3 mm to the pupillary diameter in standard illumination, one could make an estimation of the graft diameter. CONCLUSIONS: Rotational autokeratoplasty has a definite role in places where donor corneal tissue is scarce, in patients in whom long-term steroids are a risk or in situations where follow up of patients is difficult. Rejection is a theoretical impossibility, but late endothelial failure could occur, requiring regrafting. Rotational autokeratoplasty should be seriously considered as an alternative to conventional penetrating keratoplasty.  相似文献   
79.
P3 component of the endogenous cerebral evoked response is a sophisticated, objective and quantitative approach to assess higher functions of the brain. This test was employed using auditory 'odd ball' paradigm to assess cognitive functions in thirty non insulin dependent diabetic patients (NIDDM) aged 43.6 +/- 9 yrs with poor blood glucose control. (HbAlc. 9.9 +/- 1.0%). The peak latencies of N2, P3 components of event related evoked potentials obtained in these patients were compared with 30 age and sex matched non diabetic healthy controls. Latencies of these potentials were: N2 = 248.0 +/- 36.3, P3 = 391.6 +/- 49.9 msec in NIDDM as compared to 220.6 +/- 26.4, 326.2 +/- 26.8 msec in controls and were highly significant (P < 0.001). The duration of disease, blood glucose level or the physical parameters of height, weight and blood pressure did not show any correlation with N2 or P3 latencies or amplitude. These findings provide an electrophysiological evidence of delayed cognition in poorly controlled NIDDM cases.  相似文献   
80.
Didemnin B (NSC-325319), a new depsipeptide isolated from a Caribbean tunicate, has been evaluated in a clinical phase I study. The drug was administered in a schedule of a 4 weekly intravenous injection in a six-weeks cycle. Fifty-three patients received 71 evaluable cycles in an escalated dose ranging from 0.4 mg/m2/week to 2.5 mg/m2/week. No hematological toxicity was demonstrated at any dose level. Without prophylactic antiemetics nausea and vomiting was dose limiting at 1.2 mg/m2/week. Due to the use of Cremophor EL as a solvent, hypersensitivity reactions occurred in 9 patients. These reactions occurred following prior exposure to the drug and were commonly seen at the 3rd dose. They were not dose related but became more frequent at 1.5 mg/m2/week necessitating prophylactic treatment with H1 and H2 receptor blocking agents. Non-hematological toxicities included mild diarrhea, mucositis, anorexia, headaches, and local phlebitis. The dose- limiting toxicity was generalized weakness which became severe and disabling in 3 of 6 patients treated at 2.5 mg/m2/week. No objective responses were documented in 39 patients with evaluable disease. The recommended dose for phase II studies was 2.3 mg/m2/week × 4 4 in a 6-weeks cycle given with prophylactic antiemetics and H1 and H2 receptor blocking agents.  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-23

京公网安备 11010802026262号