全文获取类型
收费全文 | 9381篇 |
免费 | 741篇 |
国内免费 | 25篇 |
专业分类
耳鼻咽喉 | 71篇 |
儿科学 | 272篇 |
妇产科学 | 173篇 |
基础医学 | 1257篇 |
口腔科学 | 222篇 |
临床医学 | 1190篇 |
内科学 | 2059篇 |
皮肤病学 | 72篇 |
神经病学 | 857篇 |
特种医学 | 259篇 |
外科学 | 1036篇 |
综合类 | 102篇 |
一般理论 | 5篇 |
预防医学 | 992篇 |
眼科学 | 297篇 |
药学 | 642篇 |
中国医学 | 8篇 |
肿瘤学 | 633篇 |
出版年
2022年 | 85篇 |
2021年 | 155篇 |
2020年 | 95篇 |
2019年 | 129篇 |
2018年 | 168篇 |
2017年 | 137篇 |
2016年 | 153篇 |
2015年 | 188篇 |
2014年 | 255篇 |
2013年 | 327篇 |
2012年 | 454篇 |
2011年 | 516篇 |
2010年 | 271篇 |
2009年 | 247篇 |
2008年 | 389篇 |
2007年 | 466篇 |
2006年 | 470篇 |
2005年 | 403篇 |
2004年 | 391篇 |
2003年 | 337篇 |
2002年 | 383篇 |
2001年 | 309篇 |
2000年 | 301篇 |
1999年 | 243篇 |
1998年 | 93篇 |
1997年 | 83篇 |
1996年 | 74篇 |
1995年 | 71篇 |
1994年 | 68篇 |
1993年 | 57篇 |
1992年 | 202篇 |
1991年 | 227篇 |
1990年 | 193篇 |
1989年 | 221篇 |
1988年 | 153篇 |
1987年 | 186篇 |
1986年 | 187篇 |
1985年 | 164篇 |
1984年 | 129篇 |
1983年 | 87篇 |
1982年 | 56篇 |
1981年 | 63篇 |
1980年 | 71篇 |
1979年 | 115篇 |
1978年 | 69篇 |
1977年 | 57篇 |
1975年 | 60篇 |
1974年 | 58篇 |
1973年 | 62篇 |
1971年 | 63篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
161.
Olson RE 《Journal of the American Dietetic Association》2000,100(1):28-32
The proponents of fat-restricted diets for children argue that low-fat diets given in childhood will prevent the development of atherosclerosis in adulthood, low-fat diets given a childhood will condition children to prefer low-fat diets in adulthood, and low-fat diets for children are safe. There is no evidence that low-fat diets in childhood will prevent atherosclerosis in adulthood. In fact, studies of migrating populations indicate that immigrants to the United States from Third World countries who consumed low-fat diets in childhood take on the character of their new environments, including higher serum cholesterol levels and more coronary disease. The prevalence of fatty streaks in childhood bears little relationship to the prevalence of atheromatous plaques in adulthood. In fact, girls have more aortic fatty streaks and higher serum cholesterol values in childhood than boys, but fewer plaques in adulthood and less coronary disease. From the PDAY study, it has also been learned that hypercholesterolemia in childhood enhances fatty streak formation, but not that of plaques. It now seems established from autopsy studies that the progression of atherosclerosis from fatty streaks to plaque is arrested in childhood and does not begin to a significant extent until after puberty in males and after menopause in females. So the oft-repeated statement that atherosclerosis begins in childhood is semantically true but very misleading. The particularly harmful form of atherosclerosis (the plaque) does not become significant until much beyond puberty. The effects of low-fat, low-cholesterol diets on serum lipids and lipoproteins are of a lesser magnitude in children than in adults. The 0.78 mmol/L decrease in LDL cholesterol in the intervention group from controls (change 1.5%) in the DISC study was biologically insignificant and reflects the tighter control of lipoprotein and cholesterol synthesis in children compared with adults. It must be remembered that the human body synthesizes all of the cholesterol it needs from acetyl CoA. In general, the larger the amount of dietary cholesterol absorbed, the smaller the rate of biosynthesis of cholesterol. In some adults and most children this homeostatic control is nearly perfect, but in many adults the correction in biosynthesis of cholesterol with increased dietary input is imperfect and LDL cholesterol values increase. The second argument of the proponents of low-fat diets for children is that they are conditioned to continue low-fat diets in adulthood. From the studies of Birch and Fisher (51) this prediction seems unlikely. These investigators found that restricting access to palatable foods enhanced the interest of 3- to 5-year-old children in those foods and increased their desire to obtain and consume those foods. They concluded that "stringent parental controls can potentiate preference for high-fat energy-dense foods, limit children's acceptance of a variety of foods and disrupt children's regulation of energy intake." Brosin (52) has also observed that food restriction in childhood may lead to gluttony in adulthood. Finally, the claim that low-fat diets are safe in childhood is based on observations over too short a time to establish safety. It is true that growth and development of children studied in the DISC study was not changed from the expected increments, but that is not proof of long-term safety. In addition, the lower content of essential nutrients in low-fat, low-cholesterol diets (calcium, zinc, magnesium, phosphorus, vitamin E, vitamin B-12, thiamin, niacin, and riboflavin) must be considered along-term risk (53,54). Furthermore, the published studies of the safety of low-fat diets have been conducted under intensive surveillance in medical centers, conditions very different from those in the homes of free-living families. 相似文献
162.
Olson RE 《The American journal of clinical nutrition》2000,71(5):1031-1032
163.
164.
Marin Morales LA Gomez Navalon LA Zorrilla Ribot P Salido Valle JA 《Acta orthopaedica Belgica》2000,66(3):272-278
Nineteen cases of osteoarthritis of the knee with valgus deformity in 17 patients were treated by femoral supracondylar varus osteotomy (17 cases) or by high tibial varus osteotomy (2 cases) over the last 15 years. Fixation was performed using a 95 degrees AO blade-plate in 13 of the femoral osteotomies and a straight plate in the other four. The mean follow-up time was 6.5 years. The valgus deformity was idiopathic in 14 cases, secondary to rheumatoid arthritis in 2 cases and to tibial valgus in one case. The Hospital for Special Surgery (HSS) score was used to evaluate the clinical results: nearly 75% were excellent or good. The causes related to poor results are analyzed regarding indication and surgical technique. It appears that varus osteotomy is an effective procedure for the treatment of osteoarthritis of the knee with valgus deformity, above all in order to alleviate pain, although the operation requires precision, and correct selection of patients is of prime importance. 相似文献
165.
Cystic fibrosis (CF) is the most frequent, lethal genetic disorder among northern Europeans. The etiology of this autosomal recessive disease is known to be a defect in the cAMP activation of chloride (Cl-) channels in secretory cells in many organs of the body. Although this defect usually leads to severe lung disease, many of these patients also have nutritional deficiencies. Nutrition is one of the key components in the management of CF. Patients are at high risk for malnutrition, which may result in accelerated progression of the disease and increased morbidity. This review will discuss nutrition recommendations for calories, protein, vitamins and minerals, and enteral and parenteral nutrition support practices. 相似文献
166.
David K Warren Anand Nitin Cheri Hill Victoria J Fraser Marin H Kollef 《Infection control and hospital epidemiology》2004,25(2):99-104
OBJECTIVE: To determine the occurrence of co-colonization or co-infection with VRE and MRSA among medical patients requiring intensive care. DESIGN: Prospective, single-center, observational study. SETTING: A 19-bed medical ICU in an urban teaching hospital. PATIENTS: Adult patients requiring at least 48 hours of intensive care and having at least one culture performed for microbiologic evaluation. RESULTS: Eight hundred seventy-eight consecutive patients were evaluated. Of these patients, 402 (45.8%) did not have microbiologic evidence of colonization or infection with either VRE or MRSA, 355 (40.4%) were colonized or infected with VRE, 38 (4.3%) were colonized or infected with MRSA, and 83 (9.5%) had co-colonization or co-infection with VRE and MRSA. Multiple logistic regression analysis demonstrated that increasing age, hospitalization during the preceding 6 months, and admission to a long-term-care facility were independently associated with colonization or infection due to VRE and co-colonization or co-infection with VRE and MRSA. The distributions of positive culture sites for VRE (stool, 86.7%; blood, 6.5%; urine, 4.8%; soft tissue or wound, 2.0%) and for MRSA (respiratory secretions, 34.1%; blood, 32.6%; urine, 17.1%; soft tissue or wound, 16.2%) were statistically different (P < .001). CONCLUSIONS: Co-colonization or co-infection with VRE and MRSA is common among medical patients requiring intensive care. The recent emergence of vancomycin-resistant Staphylococcus aureus and the presence of a patient population co-colonized or co-infected with VRE and MRSA support the need for aggressive infection control measures in the ICU. 相似文献
167.
168.
Jeanine A Harrigan Chad M Vezina Barbara P McGarrigle Noreen Ersing Harold C Box Alexander E Maccubbin James R Olson 《Toxicological sciences》2004,77(2):307-314
Chemical-DNA adducts provide an integrated measure of exposure, absorption, bioactivation, detoxification, and DNA repair following exposure to a genotoxic agent. Benzo[a]pyrene (BaP), a prototypical polycyclic aromatic hydrocarbon (PAH), can be bioactivated by cytochrome P-450s (CYPs) and epoxide hydrolase to genotoxic metabolites which form covalent adducts with DNA. In this study, we utilized precision-cut rat liver and lung slices exposed to BaP to investigate tissue-specific differences in chemical absorption and formation of DNA adducts. To investigate the contribution of bioactivating CYPs (such as CYP1A1 and CYP1B1) on the formation of BaP-DNA adducts, animals were also pretreated in vivo with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) prior to in vitro incubation of tissue slices with BaP. Furthermore, the tissue distribution of BaP and BaP-DNA adduct levels from in vivo studies were compared with those from the in vitro tissue slice experiments. The results indicate a time- and concentration-dependent increase in tissue-associated BaP following exposure of rat liver and lung tissue slices to BaP in vitro, with generally higher levels of BaP retained in lung tissue. Furthermore, rat liver and lung slices metabolized BaP to reactive intermediates that formed covalent adducts with DNA. Total BaP-DNA adducts increased with concentration and incubation time. Adduct levels (fmol adduct/microg DNA) in lung slices were greater than liver at all doses. Liver slices contained one major and two minor adducts, while lung slices contained two major and 3 minor adducts. The tissue-specific qualitative profile of these adducts in tissue slices was similar to that observed from in vivo studies, further validating the use of this model. Pretreatment of animals with TCDD prior to in vitro incubation with BaP potentiated the levels of DNA adduct formation. TCDD pretreatment altered the adduct distribution in lung but not in liver slices. Together, the results suggest that tissue-specific qualitative and quantitative differences in BaP-DNA adducts could contribute to the lung being a target tissue for BaP carcinogenesis. Furthermore, the results validate the use of precision-cut tissue slices incubated in dynamic organ culture as a useful model for the study of chemical-DNA adduct formation. 相似文献
169.
Successful use of cryocrit for monitoring response to therapeutic plasma exchange in type 1 cryoglobulinemia
下载免费PDF全文
![点击此处可从《Journal of clinical apheresis》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Waldenstrom macroglobulinemia (WM) is a clinical syndrome that is defined as lymphoplasmacytic lymphoma with bone marrow involvement and IgM monoclonal gammopathy of any level. In some instances WM can result in a type I cryoglobulinemia with very high cryocrits, which is unusual in type II and III cryoglobulinemia. We describe a case of an 80 year old male with WM, severe type I cryoglobulinemia, and an extremely elevated cryocrit (69%). Over the course of five weeks we performed nine therapeutic plasma exchanges (TPE), and after seven treatments his cryocrit had decreased to 6% with improvement in his symptoms. By monitoring his cryocrit throughout his TPE sessions, we were able to assess his response to treatment, determine the ideal length of treatment in addition to his symptomatic improvement. J. Clin. Apheresis 31:403–404, 2016. © 2015 Wiley Periodicals, Inc. 相似文献
170.
Thomas A Olson 《The lancet oncology》2013,14(9):792-793