全文获取类型
收费全文 | 798篇 |
免费 | 39篇 |
国内免费 | 39篇 |
专业分类
耳鼻咽喉 | 11篇 |
儿科学 | 42篇 |
妇产科学 | 6篇 |
基础医学 | 68篇 |
口腔科学 | 40篇 |
临床医学 | 104篇 |
内科学 | 181篇 |
皮肤病学 | 10篇 |
神经病学 | 20篇 |
特种医学 | 102篇 |
外科学 | 55篇 |
综合类 | 18篇 |
一般理论 | 1篇 |
预防医学 | 94篇 |
眼科学 | 3篇 |
药学 | 81篇 |
中国医学 | 1篇 |
肿瘤学 | 39篇 |
出版年
2023年 | 6篇 |
2021年 | 8篇 |
2019年 | 9篇 |
2018年 | 15篇 |
2017年 | 7篇 |
2015年 | 11篇 |
2014年 | 15篇 |
2013年 | 21篇 |
2012年 | 22篇 |
2011年 | 19篇 |
2010年 | 24篇 |
2009年 | 14篇 |
2008年 | 19篇 |
2007年 | 50篇 |
2006年 | 23篇 |
2005年 | 30篇 |
2004年 | 25篇 |
2003年 | 21篇 |
2002年 | 21篇 |
2001年 | 10篇 |
2000年 | 23篇 |
1999年 | 13篇 |
1998年 | 25篇 |
1997年 | 22篇 |
1996年 | 29篇 |
1995年 | 13篇 |
1994年 | 25篇 |
1993年 | 10篇 |
1992年 | 18篇 |
1991年 | 26篇 |
1990年 | 23篇 |
1989年 | 27篇 |
1988年 | 29篇 |
1987年 | 21篇 |
1986年 | 22篇 |
1985年 | 32篇 |
1984年 | 17篇 |
1983年 | 11篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 12篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1975年 | 10篇 |
1974年 | 5篇 |
1972年 | 4篇 |
1971年 | 6篇 |
1970年 | 4篇 |
1969年 | 5篇 |
排序方式: 共有876条查询结果,搜索用时 15 毫秒
1.
2.
E J Mayer B W Alderman J G Regensteiner J A Marshall W L Haskell J Baxter R F Hamman 《The American journal of clinical nutrition》1991,53(4):812-820
We evaluated the consistency of three questionnaire methods of assessing work and leisure activity in the rural biethnic population of the San Luis Valley Diabetes Study. A 7-d physical activity recall (PAR), a ranking of usual activity, and a history of usual participation in vigorous activity were used. Energy expenditure (kJ.kg-1.wk-1) (EE) was estimated from PAR. Subjects were 503 adults [49% non-Hispanic white (NHW), 51% Hispanic]. Physical activity at work rather than leisure-time activity largely determined total energy expenditure. Average EE at work increased with work rank for all subjects combined [mean EE (SEE) for rank 1 (low) = 324.2 (24.4), rank 4 (high) = 874.0 (102.1)] and within sex, ethnic, and occupational subgroups. Leisure EE increased with leisure rank only for NHW men and employed women. Similar patterns were observed in comparisons of PAR data with history of vigorous activity. Further development and validation of instruments appropriate for use across population subgroups are needed. 相似文献
3.
In 44 patients with one or more calculi in the upper two-thirds of the ureter, single-stage percutaneous nephrolithotomy was performed through a middle or upper calyceal nephrostomy after cystoscopic placement of an occlusion balloon catheter distal to the calculus; in 42, the procedure was successful. The occlusion balloon catheter permitted retrograde opacification of all systems for enhanced renal puncture. In the last 30 patients an attempt was made either to push the calculus upward mechanically or to flush it upward into the renal pelvis with carbon dioxide or dilute contrast material. This was successful in 24 of these patients. Prior overnight occlusion of the ureter by means of ureteral dilatation further facilitates dislodgment of the calculus, which was successful in 12 of 13 patients. 相似文献
4.
The effect of vitamin C nutriture on complement component C1q concentrations in guinea pig plasma 总被引:2,自引:0,他引:2
This study shows that guinea pigs fed 100 times the amount of vitamin C needed for growth and for prevention of scurvy have elevated levels of complement component C1q. C1q is a plasma protein rich in hydroxyproline, an amino acid whose biosynthesis requires ascorbate. C1q is essential for host defense against pathogens, both as a component of the classical complement pathway and as an opsonin in the phagocytosis process. We measured C1q in vitamin C-depleted guinea pigs that had been repleted for 4 wks with the following daily doses of ascorbate (mg/100 g body wt): 0.50 (suboptimal), 2.0 (adequate), 10 (ample) and 50 (tissue saturating). We measured C1q in three ways: indirectly by quantifying protein-bound hydroxyproline and directly by hemolytic assay and by immunodiffusion against anti-C1q. Regardless of the method, plasma C1q was 30-50% higher in animals fed tissue-saturating ascorbate than in those fed adequate or suboptimal amounts of the vitamin (p less than 0.05, one-way analysis of variance, least significant difference test). These data confirm and significantly extend earlier work that provided indirect evidence for a relationship between C1q and ascorbate nutriture in the guinea pig. They are consistent with a possible relationship between ascorbate nutriture and host defense. 相似文献
5.
Braffman BH; Coleman BG; Ramchandani P; Arger PH; Nodine CF; Dinsmore BJ; Louie A; Betsch SE 《Radiology》1994,190(3):797
6.
7.
Lung cancer stands as the most important malignant neoplasm in the United States because of its high prevalence, increasing incidence, high rate of mortality, and great potential for prevention through the control of cigarette smoking. The World Health Organization (WHO) classification of lung cancer identifies four major types: squamous cell carcinoma, adenocarcinoma, large cell carcinoma, and small cell carcinoma. These tumors are commonly divided into two groups based on differences in their biology and treatment: small cell (SCLC) and non-small cell carcinomas (NSCLC). This review analyzes NSCLC with a strong emphasis on the practical aspects of treatment. We give recommendations about smoking cessation and early diagnosis through screening of high-risk individuals. We review contemporary diagnostic and staging techniques in the context of the new international TNM system of staging. Subsequent discussions of treatment are based on this new staging system. We stress the pivotal role of surgery for the management of local disease, and in addition present the potential contributions of newer radiation therapy techniques. We examine chemotherapy in detail, including a review of the comparative activity of the available cytotoxic agents against NSCLC, the relative contribution of combination chemotherapy, and the role of surgical adjuvant treatment with either chemotherapy or immunotherapy. We advise that patients with NSCLC be treated under the aegis of modern clinical trials of new therapy whenever possible. When this is not possible, we recommend an individualized approach based on such factors as the patient's age, general state of health, cardiopulmonary status, psychosocial status, and personal system of values. 相似文献
8.
Linda Klieman MSN ANP Shauna Hyde MS RD CDE Kathy Berra MSN ANP William Haskell PhD 《Current cardiovascular risk reports》2007,1(4):335-339
The benefits of regular physical activity in older persons are numerous and well established. Regular physical activity in
older adults is associated with an overall improvement in health, functional capacity, quality of life, and independence.
Many questions arise for healthcare providers regarding an older person’s ability and motivation to be physically active.
The healthcare provider has a unique opportunity to assess the older client’s incentives, preferences, and abilities for physical
activities, as well as to prescribe a safe, appropriate, and enjoyable exercise plan. The exercise precription can be simple
yet thorough enough to ensure benefits in an older person’s health and functional capacity. 相似文献
9.
H Y G?ksu M O Degteva N G Bougrov R Meckbach E H Haskell I K Bailiff L B?tter-Jensen H Jungner P Jacob 《Health physics》2002,82(1):94-101
Bricks collected from a contaminated village (Muslyumovo) of the lower Techa river valley, Southern Urals, Russia, were measured using thermoluminescence and optically stimulated luminescence by four European laboratories and a U.S. laboratory to establish and compare the applied dose reconstruction methodologies. The bricks, collected from 60-100-year-old buildings, had accumulated a relatively high dose due to natural sources of radiation in the brick and from the surrounding environment. This work represents the results of a first international intercomparison of luminescence measurements for bricks from the Southern Urals. The luminescence measurements of absorbed dose in bricks collected from the most shielded locations of the same buildings were used to determine the background dose due to natural sources of radiation and to validate the age of the bricks. The absorbed dose in different bricks measured by four laboratories using thermoluminescence and optically stimulated luminescence at a depth of 10 +/- 2.5 mm from the exposed brick surface agreed within +/-21%. After subtraction of the natural background dose, the absorbed dose in brick due to contaminated river sediments and banks was calculated and found to range between 150 and 200 mGy. The cumulative doses in brick due to man-made sources of radiation at 100 and 130 mm depths in the bricks were also measured and found to be consistent with depth dose profiles calculated by Monte Carlo simulations of photon transport for possible source distributions. 相似文献
10.
Metastasis of unknown origin 总被引:1,自引:0,他引:1
Metastasis of unknown origin (MUO) constitutes between 5% and 10% of all noncutaneous cancers. An MUO is defined as a metastatic tumor for which the site of origin is not suggested by thorough history, physical examination, chest x-ray studies, routine blood and urine studies, and histologic evaluation. Two major groups of MUO can be defined: MUO to lymph nodes only (N1-3), and MUO to visceral sites. The prognosis may be quite good for patients with MUO limited to lymph nodes in the mid to high cervical, axillary, and groin areas. However, MUO in other lymph node areas is far more serious, with the possible exception of that in patients with a new syndrome, i.e., "advanced poorly differentiated carcinoma of unknown primary origin." There is some suggestion that these patients may respond to cisplatin-based combination chemotherapy. Patients with MUO to visceral sites have a poor prognosis. However, metastases from some primary tumors are sensitive to chemotherapy and a limited search for these tumors should be undertaken. These tumors include leukemia-lymphoma, germ cell tumors, small cell carcinoma of the lung, adenocarcinomas of the breast, ovary, endometrium, thyroid, or prostate, and possibly adrenal carcinoma. We start by reviewing the biochemical events of metastasis that may be targets for therapy. The importance of a correct tissue diagnosis is then considered, including the role of standard histochemistry, electron microscopy, enzyme histochemistry, and immunohistochemistry. The relatively limited value of radiologic tests in localizing the primary site of origin of the tumor is emphasized, as well as the limited role of currently available biomarkers. We conclude by discussing the treatment of each of the subtypes of MUO. 相似文献