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   1418篇
  免费   211篇
  国内免费   3篇
耳鼻咽喉   2篇
儿科学   54篇
妇产科学   18篇
基础医学   259篇
口腔科学   17篇
临床医学   156篇
内科学   286篇
皮肤病学   17篇
神经病学   168篇
特种医学   253篇
外科学   60篇
综合类   50篇
预防医学   116篇
眼科学   15篇
药学   105篇
  1篇
中国医学   8篇
肿瘤学   47篇
  2021年   9篇
  2018年   10篇
  2017年   11篇
  2016年   16篇
  2015年   20篇
  2014年   17篇
  2013年   31篇
  2012年   36篇
  2011年   52篇
  2010年   42篇
  2009年   35篇
  2008年   33篇
  2007年   40篇
  2006年   40篇
  2005年   34篇
  2004年   24篇
  2003年   29篇
  2002年   27篇
  2001年   28篇
  2000年   30篇
  1999年   22篇
  1998年   40篇
  1997年   44篇
  1996年   44篇
  1995年   57篇
  1994年   52篇
  1993年   45篇
  1992年   28篇
  1991年   27篇
  1990年   49篇
  1989年   66篇
  1988年   47篇
  1987年   55篇
  1986年   51篇
  1985年   53篇
  1984年   32篇
  1983年   28篇
  1982年   24篇
  1981年   33篇
  1980年   36篇
  1979年   23篇
  1978年   24篇
  1977年   21篇
  1976年   24篇
  1975年   18篇
  1974年   12篇
  1973年   11篇
  1972年   7篇
  1971年   11篇
  1970年   7篇
排序方式: 共有1632条查询结果,搜索用时 162 毫秒
1.
Risk is a concept inherent in every medical procedure. It can be defined as the probability of an adverse event in a defined population over a specified period of time. In the frame of food allergy management, it might be related to a diagnostic procedure, a treatment, or the consumption of foods. The risk of an adverse event can also be augmented by individual factors. This rostrum article discusses various aspects faced by children with food allergies in the light of risk, and their practical implications. Identifying personal risks for severe reaction, such as unstable asthma, and correcting them whenever possible also contribute to a reduction of the risk inherent to food allergy. Among the facets discussed, oral food challenges (OFC) are the most common diagnostic procedures implying an inherent risk. The risk of OFCs can be minimized by correct indication and timing of the test, a safe setting, as well as by ensuring that the patient is otherwise well without potential stressor potentially increasing the risk of a more severe reaction. Oral immunotherapy (OIT) has been studied as a potential treatment for increasing the threshold dose for reaction, and thus reducing the risk of accidental reaction. Nevertheless, the procedure is not devoid of risk as the patients may and do often react during the course of the procedure. Ingestion of trace amounts in processed foods, mainly in community settings such as restaurants, schools, or day care, represents a potential risk of reactions, although for a minority of patients. Precautionary allergen labeling (PAL) is a widespread strategy to reduce the potential risk of reactions due to traces. However, PAL is currently inefficient due to inconsistent labeling, also not indicating a clear maximum amount possibly present in the manufactured food. Finally, cost-effectiveness needs to be considered in risk management, as many risk reduction procedures are clearly not cost-effective.  相似文献   
2.
Accumulating evidence suggests that antipsychotics (APs) that lead to sustained blockade of dopamine D(2) receptors are more likely to induce acute extrapyramidal side effects (EPS) compared to APs that only occupy D(2) receptors transiently. It is unclear, however, whether a similar relationship exists for long-term AP-induced motoric side effects like tardive dyskinesia (TD). The objective of this study was to ascertain whether transient (via daily subcutaneous (s.c.) injections) vs continuous (via osmotic minipump) AP-induced D(2) receptor occupancy differentially affects the development of haloperidol-induced vacuous chewing movements (VCMs), an animal model of TD. Six groups of 12 rats received 0.1, 0.25, or 1 mg/kg of haloperidol or vehicle (n=36) via osmotic minipump (to provide within-day sustained) or daily s.c. injection (within-day transient) for 8 weeks. VCMs were measured on a weekly basis and D(2) occupancy levels were measured in vivo using [(3)H]-raclopride at the end of the experiment. Minipump-treated rats developed HAL dose-dependent D(2) occupancies of 0.1 mg/kg/day (57%), 0.25 mg/kg/day (70%), and 1 mg/kg/day (88%). S.C.-treated rats also developed HAL dose-dependent D(2) occupancies of 0.1 mg/kg/day (83% peak, 3% trough), 0.25 mg/kg/day (89% peak, 0% trough), and 1 mg/kg/day (94% peak, 17% trough). A total of 43% of rats given 0.25 and 1 mg/kg/day of HAL via minipump developed high VCMs compared to only 8% of the rats given the same doses via daily s.c. injections. The 0.1 mg/kg dose did not give rise to VCMs beyond vehicle levels regardless of the route of administration. These findings support the contention that D(2) occupancy levels induced by chronic HAL must be high and sustained through the day before significant risk of VCMs, and perhaps also TD, emerges.  相似文献   
3.
Recently, public and private efforts have been mounted to promote screening mammography. To assess recent trends in the percentage of women 50 years of age and older who have had a screening mammogram, we analyzed data from interviews from women from 33 states who participated in the 1987 Behavioral Risk Factor Surveillance System. Our study group included 8,402 women 50 years of age and older who had visited a physician for a routine checkup in the last year; among these 8,402 women, only 29% reported having had a screening mammogram in the past year. However, of the women in the study group, the percentage who had a screening mammogram in the last year showed a relative increase of 38% during 1987, from 24% for women interviewed in the first quarter of 1987 to 33% for women interviewed in the fourth quarter. However, not all groups of patients benefited equally from the observed trend--the absolute and relative increases in the percentage of women screened were lowest for women who were older, less educated, in low-income groups, and who had poor personal health practices. Although the percentage of women 50 years of age and older who reported being screened increased dramatically during 1987, special efforts are needed to reach the patient groups that are being left behind in the trend toward increased use of screening mammograms.  相似文献   
4.
The cyst form of Toxoplasma gondii has been implicated as a cause of recrudescence of the latent infection in congenitally infected patients and in the immunocompromised host. A method was developed to evaluate the effect of drugs on the cyst form of the parasite and used to evaluate a variety of therapeutic agents. The most active compounds against the cyst form in vitro were arprinocid-N-oxide, azithromycin, and the hydroxynaphthoquinone 566C80.  相似文献   
5.
6.
The beStent is a new stainless steel, balloon-expandable mesh stent which has a unique serpentine design. Rotation of the unique low stress junctions upon expansion leads to orthogonal locking of the wires, maximizing radial strength and assuring zero shortening. The stent has delineating gold markers which assure precise positioning. We aim to present the initial acute results in a pilot registry for stent evaluation. Two hundred eighty-four stents were used in a total of 217 patients (age 57.9 ± 3.10 years; 178 males; 39 females) in seven centers, for variable indications. Stents of 15-, 25-, and 35-mm length were used. The arteries treated were the left anterior descending (n = 112, 42%), circumflex (n = 54, 20.2%), right coronary (n = 95, 35.5%), left main (n = 1, 0.4%), and vein graft (n = 5, 1.9%). Lesion types were: A in 42 patients (16.5%); B1 in 53 patients (20.7%); B2 in 81 patients (31.8%); and C in 79 patients (31%). One hundred fifty-nine patients required one stent, 40 patients required two stents, and 18 patients required three or more stents. Anticoagulation protocol included procedural heparin with aspirin with/without ticlopidine. Smooth angiographie results were obtained in all cases with no plaque herniation. Acute angiographic success was obtained in 97% of the patients, and acute clinical success in 95% of the patients. Complications within 30 days were: 3 deaths (1.4%) (2 noncardiac); 2 (0.9%) myocardial infarctions; and 2 (0.9%) stent thromboses. Therefore, the beStent is useful in treatment of complex lesions of variable length and complexity, providing excellent acute results with a low complication rate, in spite of unfavorable basic clinical and angiographie characteristics.  相似文献   
7.
8.
To evaluate the utility of the polymerase chain reaction (PCR) for documenting herpes simplex virus (HSV) in persons with reactivated genital lesions viral isolation was compared with a recently developed PCR method. Three women experiencing four episodes of recurrent genital herpes were followed for 10 days per episode with daily examination and duplicate swabs of the lesions, one for HSV culture and one for PCR. HSV type 2 was cultured from three of four episodes and the mean duration of viral isolation from recurrent genital lesions was 2.6 days. PCR detected HSV DNA from lesion swabs during all four episodes, and HSV DNA was positive for an average of 6.8 days. HSV DNA was demonstrated in ulcerative lesions on 15 of 17 days versus 3 of 17 days by viral isolation (P less than .01). HSV PCR became negative when the lesions reepithelialized. These data suggest that PCR is a more sensitive measure of HSV infection than routine viral culture and that PCR detects the presence of HSV at times when culture is negative.  相似文献   
9.
In animals, perfluorochemicals (PFCs) are effective ultrasound (US) contrast agents that produce hepatic, splenic, and tumor enhancement. The use of Fluosol-DA 20%, an emulsion of perfluorodecalin and perfluorotripropylamine, was studied in nine non-critically ill patients with cancer who had liver lesions. US studies without Fluosol were compared with studies obtained 24, 48, and 72 hours after Fluosol infusion. Vital signs and extensive laboratory analyses are performed before and after Fluosol infusion. Liver metastases from colonic, pancreatic, and gastric carcinoma exhibited rim or diffuse enhancement after a Fluosol dose of 1.6 g/kg or greater. Fluosol produced echogenic enhancement of the liver and spleen relative to kidney at a dose of 2.4 g/kg, allowing the detection of nonenhancing lesions. In addition, Fluosol at a dose of 1.6 g/kg or greater allowed detection of lesions not seen before contrast medium was administered in three of the seven patients studied. There was a mild increase in the level of serum glutamic oxaloacetic transaminase in two patients, one given 2.4 and the other 3.2 g/kg of Fluosol. Mild and transient allergic reactions without change in vital signs were experienced by two patients.  相似文献   
10.
Doses of 200 mg of azithromycin per kg (body weight) administered by the oral route daily for 10 days completely protected mice against death caused by intraperitoneal infection with Toxoplasma gondii. The same treatment regimen also protected 80% of mice infected intracerebrally, which suggests that azithromycin attains active concentrations in the inflamed central nervous system.  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