全文获取类型
收费全文 | 1733643篇 |
免费 | 153143篇 |
国内免费 | 9097篇 |
专业分类
耳鼻咽喉 | 24596篇 |
儿科学 | 53762篇 |
妇产科学 | 47741篇 |
基础医学 | 252330篇 |
口腔科学 | 51294篇 |
临床医学 | 153376篇 |
内科学 | 347001篇 |
皮肤病学 | 40785篇 |
神经病学 | 137114篇 |
特种医学 | 66384篇 |
外国民族医学 | 472篇 |
外科学 | 268791篇 |
综合类 | 45880篇 |
现状与发展 | 18篇 |
一般理论 | 374篇 |
预防医学 | 115761篇 |
眼科学 | 40332篇 |
药学 | 136308篇 |
56篇 | |
中国医学 | 8689篇 |
肿瘤学 | 104819篇 |
出版年
2021年 | 14099篇 |
2019年 | 22137篇 |
2018年 | 26075篇 |
2017年 | 23237篇 |
2016年 | 24936篇 |
2015年 | 27939篇 |
2014年 | 34133篇 |
2013年 | 43893篇 |
2012年 | 49968篇 |
2011年 | 52936篇 |
2010年 | 37270篇 |
2009年 | 31941篇 |
2008年 | 47617篇 |
2007年 | 50536篇 |
2006年 | 50874篇 |
2005年 | 49482篇 |
2004年 | 46459篇 |
2003年 | 45203篇 |
2002年 | 44199篇 |
2001年 | 84116篇 |
2000年 | 86240篇 |
1999年 | 72763篇 |
1998年 | 19753篇 |
1997年 | 17438篇 |
1996年 | 17072篇 |
1995年 | 16006篇 |
1994年 | 15085篇 |
1992年 | 55665篇 |
1991年 | 53881篇 |
1990年 | 52792篇 |
1989年 | 51511篇 |
1988年 | 47550篇 |
1987年 | 46359篇 |
1986年 | 43852篇 |
1985年 | 41552篇 |
1984年 | 30208篇 |
1983年 | 25928篇 |
1982年 | 14789篇 |
1979年 | 27630篇 |
1978年 | 18908篇 |
1977年 | 16452篇 |
1976年 | 15004篇 |
1975年 | 16649篇 |
1974年 | 19461篇 |
1973年 | 18706篇 |
1972年 | 17918篇 |
1971年 | 16800篇 |
1970年 | 15555篇 |
1969年 | 15076篇 |
1968年 | 14072篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
G H Ross 《Toxicology and industrial health》1992,8(4):87-94
The essential features of treatment for chemical sensitivity are: 1) Encouraging the provision of clean air, food, water, and surroundings. 2) Identifying substances to which the patient is sensitive, with subsequent a) enhanced avoidance, or b) specific immunotherapy to reduce the patient's reactivity to those substances. 3) Assessing and enhancing the patient's nutritional status to maximize the body's ability to detoxify and to minimize the free-radical production and oxidative stress of xenobiotics. 4) Addressing concurrent problems such as infections, immunosuppression, and other medical conditions in an appropriate fashion. 5) Evaluating the patient's psychologic status and addressing any social and emotional problems in a compassionate manner. The author believes that multiple chemical sensitivity is a real condition with documented physiologic abnormalities. It is not a functional or psychologic illness or a belief system of the patient. Second, this condition is diagnosable and treatable by various means. These treatment options not only make common sense but usually result in significant improvement for these unfortunate patients, who deserve the very best efforts of their health care providers. 相似文献
112.
A Moberg Wing K Wing K Tholin R Sj?str?m B Sandstr?m G Hallmans 《European journal of clinical nutrition》1992,46(8):585-595
Exposure to cadmium via the diet is known to depend to a large extent on the intake of cereal grains, particularly the high-fibre fractions of wheat. Subjects with low iron status absorb more cadmium than those with better iron status. The purpose of the present study was to determine to what extent cadmium accumulation in human placenta is affected by the intake of grain fibre and maternal iron status during pregnancy. Thirty-nine pregnant women participated in the study. In each trimester the women were requested to complete a dietary history and to allow blood samples to be taken for haemoglobin, serum ferritin and serum thiocyanate determinations, the latter as a marker for smoking. At delivery the whole placenta was taken for the determination of the cadmium concentration. The 32 women who had serum thiocyanate levels less than 70 mumol/l, who had completed at least one dietary history and from whom a blood sample was obtained in the third trimester, were included in the final statistical analyses. In the group of women who consumed less than the median intake of grain fibre and had more than 15 micrograms ferritin/l serum in the third trimester, the placenta cadmium concentration was nearly half that in the placentae of women who had consumed more grain fibre or had lower iron status in late pregnancy. 相似文献
113.
P J Hayden C J Welsh Y Yang W H Schaefer A J Ward J L Stevens 《Chemical research in toxicology》1992,5(2):232-237
Nephrotoxic cysteine conjugates derived from a variety of halogenated alkenes are enzymatically activated via the beta-lyase pathway to yield reactive sulfur-containing metabolites which bind covalently to cellular macromolecules. Mitochondria contain beta-lyase enzymes and are primary targets for binding and toxicity. Previously, mitochondrial protein and/or DNA have been considered as molecular targets for cysteine conjugate metabolite binding. We now report that metabolites of nephrotoxic cysteine conjugates form covalent adducts with rat kidney mitochondrial phospholipids. Rat kidney mitochondria were incubated with the 35S-labeled conjugates S-(1,1,2,2-tetrafluoroethyl)-L-cysteine (TFEC), S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine (CTFC), S-(1,2-dichlorovinyl)-L-cysteine, and S-(1,2,3,4,4-pentachlorobutadienyl)-L-cysteine. Quantitation of metabolite binding to whole mitochondria and to mitochondrial protein and lipid fractions revealed that as much as 42% of the 35S-label associated with the mitochondria was found in the lipid fraction. Total lipids were also extracted from 35S-treated mitochondria and separated by thin-layer chromatography. 35S-Containing metabolites were found in the lipid fractions from mitochondria treated with each of the conjugates. Lipids from both [35S]CTFC- and [35S]-TFEC-treated mitochondria contained major 35S-labeled lipid adducts which had similar mobility by thin-layer chromatography. Fatty acid analysis, 19F and 31P NMR spectroscopy, and mass spectrometric analyses confirmed that the major TFEC and CTFC adducts are thioamides of phosphatidylethanolamine. 相似文献
114.
Two-color flow cytometry was carried out to determine the correlation between cell-mediated immunity and the levels of proteinuria in 30 patients with membranous nephropathy. Lymphocyte subpopulations were measured by two-color flow cytometry using various monoclonal antibodies of the Leu series. Clinically, the patients were divided into four stages as follows: 1. untreated nephrotic stage, 2. prednisolone (PSL) treated nephrotic stage, 3. persistent proteinuric stage (incomplete remission, ICR) and 4. complete remission (CR). Two-color flow cytometry showed a significant decrease in Leu 2a+15+ (suppressor T) cells and relative increase in Leu 3a+8+ (suppressor inducer T) cells in the untreated nephrotic stage. The mean Leu 3a+8-/Leu 2a+15+ (helper/suppressor) cell ratio was normalized in the persistent proteinuric stage or complete remission after treatment with PSL. Patients with membranous nephropathy showed a significant elevation of Leu 2a+DR+ cells after treatment with PSL. The abnormalities of suppressor T cells and suppressor inducer T cells in the peripheral blood appear to reflect the levels of proteinuria in patients with membranous nephropathy. It was concluded that PSL might stimulate Leu 2a positive cells and then increase the number of Leu 2a+15+ cells in the peripheral blood of patients with membranous nephropathy. 相似文献
115.
Premalignant lesions and nonsquamous malignancy of the penis and carcinoma of the scrotum. 总被引:2,自引:0,他引:2
P F Schellhammer G H Jordan E L Robey J T Spaulding 《The Urologic clinics of North America》1992,19(1):131-142
Premalignant lesions of the penis include cutaneous horn, balanitis xerotica obliterans, and leukoplakia. The true incidence of progression of each of these to squamous-cell carcinoma is unknown. Bowenoid papulosis, erythroplasia of Queyrat, and Bowen's disease are histologically identical to in situ carcinoma. Although the first is consistently benign, the latter two regularly evolve into invasive cancer. Malignant scrotal lesions include squamous-cell carcinoma, liposarcoma, leiomyosarcoma, basal-cell carcinoma, extramammary Paget's disease, erythroplasia of Queyrat, malignant melanoma, and metastases. Hemangioma can be confused with carcinoma. 相似文献
116.
117.
Van Landeghem G; Haese P; Lamberts L; Barata J; DeBroe M 《Nephrology, dialysis, transplantation》1997,12(8):1692-1698
Background: The association between aluminium and
dialysis encephalopathy and deterioration of the neurological state during
desferrioxamine treatment of dialysis patients is well established. At
present little is known about the speciation and the mechanisms underlying
the element's neurotoxicity. Methods. Aluminium speciation was performed in
cerebrospinal fluid samples of acutely aluminium-intoxicated dialysis
patients using a recently developed high-performance liquid
chromatographic/electro-thermal atomic absorption spectrometric hybrid
method. Results: Baseline cerebrospinal fluid
aluminium levels of samples taken shortly after the intoxication were low
but elevated (5.0±2.0 &mgr;g/l, n=3) as compared to subjects
with normal renal function (<1 &mgr;g/l). In contrast to the
situation noted in serum and to the iron speciation in cerebrospinal fluid,
aluminium was not bound to transferrin but appeared as two distinct
compounds, the main fraction eluting at the elution volume of aluminium
citrate/silicate. The second compound was not identified. Forty-four hours
after desferrioxamine administration the cerebrospinal fluid aluminium
levels had increased up to a concentration of 10.3±2.5
&mgr;g/l (n=3). This was accompanied by a change in the speciation
profile with aluminium appearing at the elution volume of aluminoxamine.
Conclusion: Our findings may contribute to a better
understanding of the neurotoxic effects of aluminium and its
desferrioxamine chelate in dialysis patients. 相似文献
118.
119.
120.
Three hundred and twenty samples of subgingival plaque were obtained from 80 caucasian girls, ranging from 10 to 13 years of age. The samples were analyzed to verify the influence of age upon colonization of the gingival sulcus by microorganisms potentially pathogenic to the periodontal tissues. The gingival and plaque status were evaluated through the gingival index (GI) and plaque index (PlI) and the microflora was assessed by the enzymatic method benzoyl-arginine-naphthylamide (BANA). The results of the BANA test were positive for 62.50% of the tested individuals and 40% of the examined sites. The influence of age was statistically significant on BANA reactivity, and the number of positive sites was greater at 11 (57.5%) than at 12 years (28.8%). 相似文献