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   58479篇
  免费   4910篇
  国内免费   121篇
耳鼻咽喉   478篇
儿科学   2371篇
妇产科学   1671篇
基础医学   8575篇
口腔科学   1298篇
临床医学   7662篇
内科学   11552篇
皮肤病学   1015篇
神经病学   5967篇
特种医学   1605篇
外科学   5310篇
综合类   553篇
一般理论   69篇
预防医学   6830篇
眼科学   860篇
药学   3435篇
  2篇
中国医学   71篇
肿瘤学   4186篇
  2023年   458篇
  2022年   674篇
  2021年   1408篇
  2020年   1050篇
  2019年   1577篇
  2018年   1737篇
  2017年   1388篇
  2016年   1530篇
  2015年   1603篇
  2014年   2039篇
  2013年   3039篇
  2012年   4221篇
  2011年   4433篇
  2010年   2388篇
  2009年   2155篇
  2008年   3606篇
  2007年   3634篇
  2006年   3589篇
  2005年   3400篇
  2004年   3284篇
  2003年   3015篇
  2002年   2720篇
  2001年   780篇
  2000年   665篇
  1999年   701篇
  1998年   680篇
  1997年   530篇
  1996年   460篇
  1995年   463篇
  1994年   403篇
  1993年   377篇
  1992年   444篇
  1991年   435篇
  1990年   366篇
  1989年   345篇
  1988年   346篇
  1987年   265篇
  1986年   259篇
  1985年   249篇
  1984年   237篇
  1983年   214篇
  1982年   191篇
  1981年   204篇
  1980年   156篇
  1979年   151篇
  1978年   138篇
  1977年   131篇
  1976年   107篇
  1975年   114篇
  1974年   125篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Ethnic and racial diversity in the United States has led to increasing interest in research on biculturalism, yet the meaning and underlying processes of biculturalism in the context of development in young adults are not well understood. Fifteen interviews were conducted with second-generation Chinese American women to explore how being bicultural fit into their lives. Data analysis yielded a developmental map that reflected their experiences throughout life as minority women. Findings suggest that biculturalism is more than being functionally competent in two cultures, it is both a behavioral and psychological orientation in life. From the findings of this study, we have increased our knowledge of Asian American women's development and provided a foundation for nursing research with minority women.  相似文献   
993.
AimFew population-based studies have been published on melanoma of unknown primary origin (MUP). This study’s aim is to describe characteristics and survival of MUP patients in the Netherlands, based on nationwide data from the Netherlands Cancer Registry (NCR).MethodsPatient and tumour characteristics of MUP patients were retrieved from the NCR. Subgroups were made according to metastatic site: nodal or distant. Survival rates were calculated using the Kaplan–Meier method. To obtain a better insight in the composition and prognosis of the MUP group, the survival was compared to that of patients with melanoma of a known primary origin (MKP), tumour-node-metastasis (TNM) stage III and IV.ResultsOf all 33,181 melanoma patients diagnosed between 2003 and 2009, 2.6% (n = 857) were diagnosed with MUP. MUP patients with nodal metastases had a similar survival as MKP stage III with macroscopic nodal involvement. After stratification according to the number of involved lymph nodes, the survival of patients with nodal metastases with one involved lymph node was not significantly different between MUP and MKP. The survival of MUP patients with two or more involved lymph nodes was slightly worse than that of MKP stage III patients with macroscopic nodal involvement with two or more involved lymph nodes. MUP patients with distant metastases had a similar survival as MKP stage IV. After stratification according to number of metastatic sites and metastatic site category, the survival in MKP stage IV patients with (sub)cutaneous metastases was slightly worse than MUP distant patients with (sub)cutaneous metastases.ConclusionsThe results of this study imply that MUP patients form a heterogeneous group, and that MUP patients with nodal metastases could be classified as stage III melanoma with macroscopic nodal involvement, and MUP patients with distant metastases as stage IV melanoma.  相似文献   
994.
Common laundry products, used in washing and drying machines, can contribute to outdoor emissions through dryer vents. However, the types and amounts of chemicals emitted are largely unknown. To investigate these emissions, we analyzed the volatile organic compounds (VOCs) both in the headspace of fragranced laundry products and in the air emitted from dryer vents during use of these products. In a controlled study of washing and drying laundry, we sampled emissions from two residential dryer vents during the use of no products, fragranced detergent, and fragranced detergent plus fragranced dryer sheet. Our analyses found more than 25 VOCs emitted from dryer vents, with the highest concentrations of acetaldehyde, acetone, and ethanol. Seven of these VOCs are classified as hazardous air pollutants (HAPs) and two as carcinogenic HAPs (acetaldehyde and benzene) with no safe exposure level, according to the US Environmental Protection Agency. As context for significance, the acetaldehyde emissions during use of one brand of laundry detergent would represent 3% of total acetaldehyde emissions from automobiles in the study area. Our study points to the need for additional research on this source of emissions and the potential impacts on human and environmental health.  相似文献   
995.
Despite the well-established use of kainate as a model for seizure activity and temporal lobe epilepsy, most studies have been performed at doses giving rise to general limbic seizures and have mainly focused on neuronal function. Little is known about the effect of lower doses of kainate on cerebral metabolism and particularly that associated with astrocytes. We investigated astrocytic and neuronal metabolism in the cerebral cortex of adult mice after treatment with saline (controls), a subconvulsive or a mildly convulsive dose of kainate. A combination of [1,2-13C]acetate and [1-13C]glucose was injected and subsequent nuclear magnetic resonance spectroscopy of cortical extracts was employed to distinctively map astrocytic and neuronal metabolism. The subconvulsive dose of kainate led to an instantaneous increase in the cortical lactate content, a subsequent reduction in the amount of [4,5-13C]glutamine and an increase in the calculated astrocytic TCA cycle activity. In contrast, the convulsive dose led to decrements in the cortical content and 13C labeling of glutamate, glutamine, GABA, and aspartate. Evidence is provided that astrocytic metabolism is affected by a subconvulsive dose of kainate, whereas a higher dose is required to affect neuronal metabolism. The cerebral glycogen content was dose-dependently reduced by kainate supporting a role for glycogen during seizure activity.  相似文献   
996.
997.
Psychoeducation has become a common intervention within mental health settings. It aims to increase people's ability to manage a life with a long‐term illness. For people with bipolar disorder, psychoeducation is one of a range of psychosocial interventions now considered part of contemporary mental health practice. It has taken on a ‘common sense’ status that results in little critique of psychoeducation practices. Using a published manual on psychoeducation and bipolar disorder as its data, Foucauldian discourse analysis was used in the present study for a critical perspective on psychoeducation in order to explore the taken‐for‐granted assumptions on which it is based. It identifies that the text produces three key subject positions for people with bipolar disorder. To practice self‐management, a person must: (i) accept and recognize the authority of psychiatry to know them; (ii) come to see that they can moderate themselves; and (iii) see themselves as able to undertake a reflexive process of self‐examination and change. These findings highlight the circular and discursive quality to the construct of insight that is central to how psychoeducation is practiced. Using Foucault's construct of pastoral power, it also draws attention to the asymmetrical nature of power relations between the clinician and the person with bipolar disorder. An effect of the use of medical discourse in psychoeducation is to limit its ability to work with ambivalence and contradiction. A critical approach to psychotherapy and education offers an alternate paradigm on which to basis psychoeducation practices.  相似文献   
998.
999.
1000.
IntroductionErectile dysfunction (ED) and lower urinary tract symptoms suggestive of benign prostatic hyperplasia (LUTS/BPH) are common in aging males and frequently occur together. Tadalafil has demonstrated efficacy in treating both conditions.AimThe study aims to evaluate the efficacy and safety of tadalafil 5 mg once daily vs. placebo over 12 weeks in treating both LUTS/BPH and ED in sexually active men. We also assessed relationships of baseline disease severity and prostate specific antigen (PSA) to outcomes.MethodsData were pooled from four multinational, randomized studies of men ≥45 years with LUTS/BPH, with analyses restricted to sexually active men with ED. Randomization (baseline) followed a 4‐week placebo run‐in; changes from baseline were assessed vs. placebo using analysis of covariance.Main Outcome MeasuresInternational Prostate Symptom Score (IPSS), IPSS subscores, Quality‐of‐Life Index (IPSS‐QoL), BPH Impact Index (BII), and International Index of Erectile Function‐Erectile Function (IIEF‐EF) Domain score were used in this study.ResultsTadalafil (N = 505) significantly improved total IPSS vs. placebo (N = 521); mean changes from baseline were ?6.0 and ?3.6, respectively (P < 0.001). Improvements in IIEF‐EF Domain score (tadalafil, 6.4; placebo, 1.4) were also significant vs. placebo, as were the IPSS storage and voiding subscores, IPSS‐QoL, and BII (all P < 0.001).No significant impact of baseline ED severity or PSA category on IPSS response was observed (interaction P values, 0.463 and 0.149, respectively). Similarly, improvement in IIEF‐EF Domain score was not significantly impacted by baseline LUTS/BPH severity or PSA category (interaction P values, 0.926 and 0.230, respectively). Improvements in IPSS and IIEF‐EF Domain score during treatment were weakly correlated (r = ?0.229). Treatment‐emergent adverse events were consistent with previous reports.ConclusionsTadalafil was efficacious and well tolerated in treating ED and LUTS/BPH in sexually active men with both conditions. Improvements in both conditions were significant regardless of baseline severity. Improvements in the total IPSS and the IIEF‐EF Domain score were weakly correlated. Porst H, Roehrborn CG, Secrest RJ, Esler A, and Viktrup L. Effects of tadalafil on lower urinary tract symptoms secondary to benign prostatic hyperplasia and on erectile dysfunction in sexually active men with both conditions: Analyses of pooled data from four randomized, placebo‐controlled tadalafil clinical studies. J Sex Med 2013;10:2044–2052.  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