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   788篇
  免费   50篇
  国内免费   5篇
耳鼻咽喉   1篇
儿科学   43篇
妇产科学   13篇
基础医学   92篇
口腔科学   28篇
临床医学   58篇
内科学   160篇
皮肤病学   17篇
神经病学   11篇
特种医学   144篇
外国民族医学   1篇
外科学   117篇
综合类   50篇
预防医学   39篇
眼科学   5篇
药学   24篇
中国医学   4篇
肿瘤学   36篇
  2023年   2篇
  2022年   2篇
  2021年   8篇
  2020年   6篇
  2019年   7篇
  2018年   17篇
  2017年   11篇
  2016年   18篇
  2015年   12篇
  2014年   22篇
  2013年   37篇
  2012年   31篇
  2011年   28篇
  2010年   51篇
  2009年   47篇
  2008年   31篇
  2007年   36篇
  2006年   24篇
  2005年   20篇
  2004年   17篇
  2003年   9篇
  2002年   8篇
  2001年   9篇
  2000年   9篇
  1999年   9篇
  1998年   34篇
  1997年   33篇
  1996年   34篇
  1995年   36篇
  1994年   23篇
  1993年   20篇
  1992年   5篇
  1991年   7篇
  1990年   9篇
  1989年   17篇
  1988年   15篇
  1987年   11篇
  1986年   17篇
  1985年   9篇
  1984年   13篇
  1983年   14篇
  1982年   13篇
  1981年   13篇
  1980年   15篇
  1979年   5篇
  1978年   8篇
  1977年   2篇
  1976年   8篇
  1975年   5篇
  1949年   1篇
排序方式: 共有843条查询结果,搜索用时 0 毫秒
21.

Background

Tuberculosis is a major disease worldwide and most research focus on risk factors for adults, although there is a marked adolescent peak in incidence. The objective of this study was to identify risk factors for tuberculosis in children aged 7 to 19.

Methods

A case control study matched by age with 169 cases and 477 controls. The study population consisted of adolescents and older children from Recife, Brazil. Cases were individuals diagnosed with tuberculosis in the control programme and controls were selected in the neighborhood of cases. Conditional logistic regression was used to identify risk factors.

Results

Cigarette smoking increased by 50% the risk of tuberculosis but that this was not statistically significant (OR?=?1.6). Other risk factors were sleeping in the same house as a case of tuberculosis (OR?=?31.6), living in a house with no piped water (OR?=?7.7) (probably as a proxy for bad living conditions), illiteracy (OR?=?3.7) and male sex (OR?=?1.8). The increase in risk with living in houses with no piped water was much more marked in males. The proportion of cases of tuberculosis attributed to contact with someone with TB was 38% and to illiteracy, lack of piped water and smoking, 20%.

Conclusion

Household contact with tuberculosis, social factors and male sex play the biggest role in determining risk of TB disease among children and adolescents in the study. We recommend further research on the relationship of cigarette smoking on tuberculosis in adolescents, and on whether the sex differentials are more marked in bad living conditions. Separate studies should be conducted in older children and in adolescents.
  相似文献   
22.
We conducted a seroprevalence survey among 500 healthy adult donors at Zanzibar National Blood Transfusion Services. Dengue virus IgG seroprevalence was 50.6% and independently associated with age and urban residence. These data will aid in building a surveillance, preparedness, and response plan for dengue virus infections in the Zanzibar Archipelago.Key words: dengue, seroprevalence, Zanzibar, viruses, vector-borne infections  相似文献   
23.

Background

The aim of this study was to identify the incidence of surgical site infections (SSIs) and postoperative complications, as defined by the Clavien–Dindo classification, after hepatic resection for metastatic colorectal cancer in patients with and without associated neoadjuvant chemotherapy.

Methods

A total of 181 patients were studied retrospectively. Patients were divided into two groups: the first group comprised patients with associated neoadjuvant chemotherapeutic treatment for liver metastases with a latency time <8 wk and the second group comprised patients without associated neoadjuvant chemotherapy.

Results

Variables of duration of liver surgery, length of total hospital stay, and length of postoperative hospital stay seem to be correlated with SSIs and postoperative complications, P < 0.005 and P < 0.0001, respectively. Duration of surgery is a risk factor for SSIs, with an odds ratio of 1.15, and for complications according to the Clavien–Dindo classification, with an odds ratio of 1.35.

Conclusions

Neoadjuvant chemotherapy was not a significant risk factor for SSIs, whereas the total length of hospital stay, length of postoperative hospital stay, and duration of surgery were independent predictors of SSIs and complications according to the Clavien–Dindo classification.  相似文献   
24.
Abstract:  The purpose of this study was to assess the predictive value of smoking history on breast cancer diagnosis in a referral clinic population. We conducted a case–control study using clinical data collected on 8,097 female patients (1,225 breast cancer cases and 6,872 controls) seen in the Mayo Clinic Breast Clinic between August 1, 1993 and November 31, 2003. Breast cancer patients and noncancer patients significantly differed with respect to age at time of the index visit (p < 0.001), number of pregnancies (p = 0.006), number of live births (p = 0.002), vital status at last known follow-up (p < 0.001), current menstruation (p < 0.001), age at menopause (p < 0.001), history of hysterectomy (p < 0.001), use of oral contraception (p = 0.05), duration of oral contraception use (p = 0.001), use of other exogenous hormones (p < 0.001), duration of exogenous hormone use (p = 0.05), breast pain at time of index visit (p = 0.002), smoking status (p < 0.001), and use of five or more alcoholic beverages per week (p = 0.002). After adjustment for these baseline characteristics, having a personal history of smoking was found to be predictive of breast cancer diagnosis (odds ratios [OR] = 1.25, p = 0.004). Other positive predictors for breast cancer diagnosis were: age (OR = 1.02, p < 0.001), history of hysterectomy (OR = 0.66, p < 0.001), prior use of oral contraception for more than 11 years (OR = 2.10, p < 0.001), and prior use of other exogenous hormones/estrogen (OR = 1.81, p < 0.001). In this referral practice having a personal history of smoking is predictive of breast cancer diagnosis. Further studies are needed to further explore this relationship.  相似文献   
25.
26.
The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a common cause of hyponatremia. We describe two infants whose clinical and laboratory evaluations were consistent with the presence of SIADH, yet who had undetectable arginine vasopressin (AVP) levels. We hypothesized that they had gain-of-function mutations in the V2 vasopressin receptor (V2R). DNA sequencing of each patient's V2R gene (AVPR2) identified missense mutations in both, with resultant changes in codon 137 from arginine to cysteine or leucine. These novel mutations cause constitutive activation of the receptor and are the likely cause of the patients' SIADH-like clinical picture, which we have termed "nephrogenic syndrome of inappropriate antidiuresis."  相似文献   
27.
The gene for retinitis pigmentosa 3 (RP3), the most frequent form of X- linked RP (XLRP), has been mapped previously to a chromosome interval of less than 1000 kbp between the DXS1110 marker and the OTC locus at Xp21.1-p11.4. Employing a novel technique, YAC Representation Hybridization (YRH)', we have recently identified a small XLRP associated microdeletion in this interval, as well as several putative exons including the 3' end of a gene that was truncated by the deletion. cDNA library screening and sequencing of a cosmid centromeric to the deletion has now enabled us to identify numerous additional exons and to detect several point mutations in patients with XLRP. The predicted gene product shows homology to RCC1, the guanine-nucleotide- exchange factor (GEF) of the Ras-like GTPase Ran. Our findings suggest that we have cloned the long-sought RP3 gene, and that it may encode the GEF of a retina-specific GTP-binding protein.   相似文献   
28.
29.

Background  

Several studies have addressed the issue of the feasibility of laparoscopic colorectal surgery in elderly patients, usually by choosing an arbitrary cut-off age limit, and retrospectively evaluating patient outcomes. The aim of this study was to assess the effects of age on the outcome of laparoscopic colorectal surgery for cancer in a single department, by comparing younger and older patients, matched by ASA score and type of operation.  相似文献   
30.

Background

Hydrocele is abnormal collection of serous fluid in the tunica vaginalis or a patent processus vaginalis. It is commonly encountered in our practice and often requires surgical treatment. However in our setting and in many underdeveloped countries, availability of general anaesthetic service is poor due to lack of trained personnel and equipment.

Objectives

To ascertain the practicability and acceptability of hydrocelectomy under sedation and local anaesthesia in Nigerian adults with hydrocele

Patients and Methods

A prospective study was carried out over a two year period on patients that had hydrocelectomy at the surgery unit of the Obafemi Awolowo University Teaching Hospitals Complex, Wesley Guild Hospital, Ilesa. Consecutive patients with diagnosis of hydrocele who consented had hydrocelectomy using intramuscular diazepam sedation and spermatic-cord block with 0.5% plane xylocaine and the scrotum infiltrated with same along the line of incision.

Results

Fifty adult patients were studied: age range 15–94 years. Eighty percent of the patients had unilateral hydrocele and the commonest type was vaginal hydrocele (94%). All patients had hydrocelectomy, 96% were under local anaesthesia while 4% were converted to general anaesthesia. All patients except one prefer to have future surgery under such local anaesthesia and sedation.

Conclusion

Hydrocelectomy under local anaesthesia and sedation is practicable and was tolerated and accepted by the adults patients studied.  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