全文获取类型
收费全文 | 61383篇 |
免费 | 3967篇 |
国内免费 | 119篇 |
专业分类
耳鼻咽喉 | 558篇 |
儿科学 | 2576篇 |
妇产科学 | 1681篇 |
基础医学 | 7705篇 |
口腔科学 | 658篇 |
临床医学 | 8949篇 |
内科学 | 10705篇 |
皮肤病学 | 904篇 |
神经病学 | 6331篇 |
特种医学 | 1289篇 |
外国民族医学 | 2篇 |
外科学 | 5092篇 |
综合类 | 727篇 |
一般理论 | 109篇 |
预防医学 | 8433篇 |
眼科学 | 806篇 |
药学 | 3945篇 |
中国医学 | 61篇 |
肿瘤学 | 4938篇 |
出版年
2023年 | 326篇 |
2022年 | 452篇 |
2021年 | 1082篇 |
2020年 | 752篇 |
2019年 | 1119篇 |
2018年 | 1282篇 |
2017年 | 1037篇 |
2016年 | 1126篇 |
2015年 | 1327篇 |
2014年 | 1817篇 |
2013年 | 2890篇 |
2012年 | 4212篇 |
2011年 | 4496篇 |
2010年 | 2509篇 |
2009年 | 2246篇 |
2008年 | 4082篇 |
2007年 | 4350篇 |
2006年 | 4163篇 |
2005年 | 4299篇 |
2004年 | 4100篇 |
2003年 | 3857篇 |
2002年 | 3558篇 |
2001年 | 648篇 |
2000年 | 507篇 |
1999年 | 617篇 |
1998年 | 747篇 |
1997年 | 659篇 |
1996年 | 524篇 |
1995年 | 530篇 |
1994年 | 458篇 |
1993年 | 394篇 |
1992年 | 403篇 |
1991年 | 346篇 |
1990年 | 317篇 |
1989年 | 340篇 |
1988年 | 330篇 |
1987年 | 299篇 |
1986年 | 277篇 |
1985年 | 272篇 |
1984年 | 289篇 |
1983年 | 249篇 |
1982年 | 269篇 |
1981年 | 258篇 |
1980年 | 204篇 |
1979年 | 182篇 |
1978年 | 156篇 |
1977年 | 120篇 |
1976年 | 100篇 |
1974年 | 132篇 |
1973年 | 106篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Giedd Jay N.; Snell John W.; Lange Nicholas; Rajapakse Jagath C.; Casey B. J.; Kozuch Patricia L.; Vaituzis A. Catherine; Vauss Yolanda C.; Hamburger Susan D.; Kaysen Debra; Rapoport Judith L. 《Cerebral cortex (New York, N.Y. : 1991)》1996,6(4):551-559
Brain magnetic resonance images (MRI) of 104 healthy childrenand adolescents, aged 418, showed significant effectsof age and gender on brain morphometry. Males had larger cerebral(9%) and cerebellar (8%) volumes (P < 0.0001 and P = 0.008.respectively), which remained significant even after correctionfor height and weight After adjusting for cerebral size, theputamen and globus pallidus remained larger in males, whilerelative caudate size was larger in females. Neither cerebralnor cerebellar volume changed significantly across this agerange. Lateral ventricular volume increased significantly inmales (trend for females), with males showing an increase inslope after age 11. In males only, caudate and putamen decreasedwith age (P = 0.007 and 0.05, respectively). The left lateralventricles and putamen were significantly greater than the rightP = 0.01 and 0.0001, respectively). In contrast, the cerebralhemispheres and caudate showed a highly consistent right greater-than-leftasymmetry (P < 0.0001 for both). All volumes demonstrateda high degree of variability. These findings highlight gender-specificmaturational changes of the developing brain and the need forlarge gender-matched samples in pediatric neuropsychiatric studies. 相似文献
102.
Critical care nurses, ethical decision-making and stress 总被引:2,自引:0,他引:2
Considerable attention has focused on describing ethical issues that critical care nurses face in their practice; however, less attention has been directed at describing the process of ethical decision-making. Systematic research linking aspects of ethical-decision making and stress is lacking. This cross-sectional study examines the relationship between selected aspects of ethical decision-making, stress and selected nurse characteristics. Sixty-one critical care nurses completed the Nurse's Ethical Decision Making—ICU Questionnaire and the Health Professions Stress Inventory. Findings revealed that nurses who selected the patient advocacy model had significantly higher nurse autonomy scores, that perceived anxiety had a negative association with nurse autonomy, and that workplace restrictions and stress were related. 相似文献
103.
In this study, ethnographic interviews were used to identify first-time fathers' experiences of the birth of their first child. Fourteen fathers were interviewed, and prenatal expectations of the experience are compared with the fathers' perceptions after the birth. Although the fathers expected to be treated as part of a laboring couple, they found that they were relegated to a supporting role. Initially the fathers were confident of their ability to support their wives, but they found that labor was more work than they had anticipated. They became fearful of the outcome, but hid these fears from their partners. Later, they found that their focus moved from their wives to their babies at the time of birth. The men all completed the experience with an enhanced respect for their wives. Fathers should be included in labor management plans and need support for their role as coach, particularly when their wives experience pain. They also need to be encouraged to eat and take a break from their wives' labor when appropriate. 相似文献
104.
Changes in intracellular pH (pHi) are thought to produce large changes in force production in the uterus. There have however, been no simultaneous measurements of pHi and force in the uterus and therefore no direct information is available about the relation between the two. We have used carboxy-SNARF (a pH-sensitive fluorophore) in small strips of longitudinal myometrium and obtained simultaneous measurements of pHi and force. SNARF did not alter contractile function, and continuous measurements of pHi could be made for 2 hours. The mean resting pHi (7.16) was similar to that reported previously. Application of weak bases rapidly raised pHi, in a concentration-dependent manner, followed by a gradual restoration of pHi to resting levels. Alkalinization greatly increased the frequency of contractions, often accompanied by a small increase in their amplitude. Removal of base produced a rebound acidification which transiently abolished contractions. Direct acidification of the cytoplasm, by application of weak acid, also abolished contractions. However the alkalinization which accompanied removal of acid, produced variable effects on force.Supported by the M.R.C. 相似文献
105.
Susan D. Ross M.D. Angela DiGeorge B.S. Janet E. Connelly B.S. Gregory W. Whiting B.S Neil McDonnell Pharm.D. 《Pharmacotherapy》1998,18(6):1290-1297
We performed a literature search for all clinical studies reporting outcomes in patients with the acquired immunodeficiency syndrome (AIDS) receiving granulocyte-macrophage colony-stimulating factor (GM-CSF) for any indication. Safety outcomes included human immunodeficiency virus replication, immune status, and frequency of opportunistic infections and neoplasms. Data were synthesized qualitatively. We identified 22 studies (274 patients): 12 addressed AIDS neutropenia, 8 AIDS cancer therapy, and 2 opportunistic infections. Viral burden was assessed by serum p24Ag in 15 studies. Nine reported no change in levels, three net decreases, and three net increases. All studies showing net increases involved patients receiving GM-CSF without a concurrent antiretroviral. The CD4 counts were unchanged in 5 studies, increased in 3, and not reported in 14. The incidence of neoplasms or new opportunistic infections was low. The literature suggests no increased risk of viral replication or clinical deterioration in patients with AIDS who take GM-CSF concurrently with zidovudine. 相似文献
106.
Darier's disease (keratosis follicularis) is a rare, dominantly inherited condition which is characterised by the presence of warty papules and plaques on the trunk, scalp and flexures. Diagnostic nail changes are present in most patients. Suprabasal clefting, acantholysis and dyskeratosis are present in involved skin and the diagnosis may be confirmed by a skin biopsy. The disease never remits. Exacerbating factors such as heat, sweating and ultraviolet light should be avoided. Topical therapy with emollients, moderately potent corticosteroids and antimicrobials may provide some symptomatic relief, but have no effect on the progress of the disease. Oral retinoids are effective in most patients. Complications such as cutaneous infections, blistering and salivary gland obstruction may occur in some patients. 相似文献
107.
108.
109.
Ellen A. Eisen Paige E. Tolbert Marilyn F. Hallock Richard R. Monson Thomas J. Smith Susan R. Woskie 《American journal of industrial medicine》1994,26(2):185-202
A case-control study of larynx cancer was conducted within a cohort of automobile workers exposed to metal working fluids, commonly referred to as machining fluids (MF). Results are based on 108 cases of larynx cancer and 5:1 matched controls. Risks associated with specific types of MF, as well as specific components of the fluids were evaluated. Based on a retrospective exposure assessment, lifetime exposures to straight and soluble fluids, grinding particulate, biocides, selected metals, sulfur, and chlorine were examined. Exposure to asbestos and acid mists at two of the three study sites was also characterized. Results suggest that straight mineral oils are associated with almost a two-fold excess in larynx cancer risk. There was also evidence of an association with elemental sulfur, commonly added to straight MF to improve the integrity of the materials under extreme pressure and heat. It is not clear whether sulfur is causally related to an excess relative risk of larynx cancer or whether the observed association is the result of unmeasured confounding by another contaminant or process feature. For example, the high stress operations that require MF enriched with sulfur are also more likely to produce polycyclic aromatic hydrocarbons (PAHs) during the process. Thus, the observed association with sulfur may be due to an association with PAH. The finding of excess risk of laryngeal cancer associated with MF is consistent with several previous reports in the literature. This is the first study, however, to distinguish straight mineral oils from other types of MF. Based on these findings, a general reduction in concentrations of straight mineral oil particulate in occupational environments would be prudent. 相似文献
110.
The potency of the anticholinesterase (antiCHE) insecticides as serine hydrolase inhibitors, and evidence for serine hydrolase activity in interleukin-2 (IL2) signalling suggest that the natural killer (NK) cell may be a target for dysregulation by antiCHE insecticides. NK cells are large granular lymphocytes (LGL) that respond to IL2 by proliferating and increasing their cytolytic efficiency. In the present study, we assessed the effects of carbaryl (CA, an antiCHE insecticide) and alpha-naphthol (NA, the major metabolite of CA) on both target cell killing per se and IL2 enhancement of target cell killing by human NK cells. Human LGL, collected from the peripheral blood of normal donors, were cultured for 4 days with human recombinant IL2 (HRIL2), then assayed by a 51Chromium (51Cr) release assay for lytic activity against human K562 cells. When added at the beginning of the culture period, CA inhibited enhancement of cytolytic efficiency in a concentration-dependent manner; at concentrations (0.5 and 5.0 microM) compatible with no cholinergic toxicity. Reduction of the effector/target cell (E/T) ratio in the 51Cr release assay markedly enhanced the observed inhibition by CA. In one experiment, inhibition increased from 6% to 20%, 17% to 35%, and 53% to 73% at 0.5, 5.0, and 50 microM CA, respectively, when E/T was reduced from 10:1 to 2.5:1. This result is consistent with reduced cytolytic efficiency of individual NK cells exposed to CA. NA had no effect at 0.5 or 5.0 microM but caused some inhibition at 50 microM. Neither CA nor NA produced LGL death. When CA or NA was added directly to the 51Cr release assay, inhibition was not observed. The mechanism of inhibition of IL2-stimulated enhancement of target cell killing is not yet known, however, the results are consistent with impairment of IL2 signalling, by CA. 相似文献